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A piezophile (from Greek "piezo-" for pressure and "-phile" for loving) is an organism with optimal growth under high hydrostatic pressure , i.e., an organism that has its maximum rate of growth at a hydrostatic pressure equal to or above 10 megapascals (99 atm; 1,500 psi), when tested over all permissible temperatures . [ 1 ] Originally, the term barophile was used for these organisms, but since the prefix "baro-" stands for weight , the term piezophile was given preference. [ 2 ] [ 3 ] Like all definitions of extremophiles , the definition of piezophiles is anthropocentric , and humans consider that moderate values for hydrostatic pressure are those around 1 atm (= 0.1 MPa = 14.7 psi ), whereas those "extreme" pressures are the normal living conditions for those organisms. Hyperpiezophiles are organisms that have their maximum growth rate above 50 MPa (= 493 atm = 7,252 psi). [ 4 ]
Though the high hydrostatic pressure has deleterious effects on organisms growing at atmospheric pressure, these organisms which are solely found at high pressure habitats at deep sea in fact need high pressures for their optimum growth. Often their growth is able to continue at much higher pressures (such as 100MPa) compared to those organisms which normally grow at low pressures. [ 5 ]
The first obligate piezophile found was a psychrophilic bacteria called Colwellia marinimaniae strain M-41. [ 6 ] [ 7 ] It was isolated from a decaying amphipod Hirondellea gigas from the bottom of Mariana Trench . The first thermophilic piezophilic archaea Pyrococcus yayanosii strain CH1 was isolated from the Ashadze site, a deep sea hydrothermal vent . [ 8 ] Strain MT-41 has an optimal growth pressure at 70MPa at 2 °C and strain CH1 has a optimal growth pressure at 52MPa at 98 °C. They are unable to grow at pressures lower than or equal to 20MPa, and both can grow at pressures above 100MPa.The current record for highest hydrostatic pressure where growth was observed is 140MPa shown by Colwellia marinimaniae MTCD1 [ 9 ] . The term "obligate piezophile" refers to organisms that are unable to grow under lower hydrostatic pressures, such as 0.1 MPa. In contrast, piezotolerant organisms are those that have their maximum rate of growth at a hydrostatic pressure under 10 MPa, but that nevertheless are able to grow at lower rates under higher hydrostatic pressures.
Most of the Earth's biosphere (in terms of volume) is subject to high hydrostatic pressure, and the piezosphere comprises the deep sea (at the depth of 1,000 m and greater) plus the deep subsurface (which can extend up to 5,000 m beneath the seafloor or the continental surface). [ 4 ] [ 10 ] The deep sea has a mean temperature around 1 to 3 °C, and it is dominated by psychropiezophiles. In contrast, deep subsurface and hydrothermal vents in the seafloor are dominated by thermopiezophiles that prosper in temperatures above 45 °C (113 °F).
Although the study of nutrient acquisition and metabolism within the piezosphere is still in its infancy, it is understood that most of the organic matter present are refractory complex polymers from the eutrophic zone . Both heterotrophic metabolism and autotrophic fixation are present within the piezosphere and additional research suggests significant metabolism of iron-bearing minerals and carbon monoxide. Additional research is required to fully understand and characterize piezosphere metabolism. [ 11 ]
High pressure has several effects on biological systems. The application of pressure results in equilibrium shifting towards state occupying small volume and it changes intermolecular distances and affects conformations. This also has an effect on the functionality of the cells. Piezophiles employ several mechanisms to adapt themselves to these high hydrostatic pressures. They regulate gene expression according to pressure and also adapt their biomolecules to differences in pressure. [ 12 ]
High pressure stabilizes hydrogen bonds and stacking interactions of the DNA. Thus it favours the double stranded duplex structure of the DNA. However, to carry out several processes like DNA replication, transcription and translation, the transition to single-strand structure is necessary, which becomes difficult as high pressure increases the melting temperature, Tm. Thus, these processes may face difficulties. [ 5 ]
When pressure increases, the fluidity of the cell membrane is decreased as due to restrictions in volume they change their conformation and packing. This decreases the permeability of the cell membrane to water and different molecules. In response to flucatuation in environment, they change their membrane structures. Piezophilic bacteria do so by varying their acyl chain length, by accumulating unsaturated fatty acids , accumulating specific polar headgroups and branched fatty acids. [ 13 ] Piezophilic archaea synthesize archaeol and cadarchaeol -based polar lipids, bipolar tetraether lipids, incorporate cyclopentane rings and increase in unsaturation. [ 14 ] [ 12 ]
The macromolecules bearing the largest effect of pressure are proteins. Just like lipids, they change their conformation and packing to accommodate changes in pressure. This affects their multimeric conformation, stability and also the structure of their catalytic sites, which changes their functionality. [ 15 ] In pressure-intolerant species, proteins tend to compact and unfold under high pressures as overall volume is reduced. Piezophilic proteins, however, tend to have less void space and smaller void spaces overall to mitigate compaction and unfolding pressures. There are also changes in the various interactions between amino acids. In general, they are very resistant to pressure. [ 16 ] [ 12 ]
Due to the functional nature of enzymes, piezophiles must maintain their activity to survive. High pressures tend to favor enzymes with higher flexibility at the cost of lower stability. Additionally, piezophilic enzymes often have high absolute (distinct from temperature or pressure) and relative catalytic activity. This allows the enzymes to maintain sufficient activity even with decreases due to temperature or pressure effects. Furthermore, some piezophilic enzymes have increasing catalytic activity with increasing pressures, though this is not a generalization for all piezophilic enzymes. [ 16 ]
As a result of high pressure, several functions may be lost in organisms that are pressure-intolerant. Effects can include loss of flagellar motility, enzyme function, and thus metabolism. It can also lead to cell death due to modifications in the cellular structure. [ 17 ] High pressures also can cause an imbalance in oxidation and reduction reactions generating relatively high concentrations of reactive oxygen species (ROS). An increased amount of anti-oxidation genes and proteins are found in piezophiles to combat the ROS as they often cause cellular damage. [ 3 ] | https://en.wikipedia.org/wiki/Piezophile |
Piezo-phototronic effect is a three-way coupling effect of piezoelectric, semiconductor and photonic properties in non-central symmetric semiconductor materials, using the piezoelectric potential (piezopotential) that is generated by applying a strain to a semiconductor with piezoelectricity to control the carrier generation, transport, separation and/or recombination at metal–semiconductor junction or p–n junction for improving the performance of optoelectronic devices, such as photodetector , [ 1 ] solar cell [ 2 ] and light-emitting diode . [ 3 ] Prof. Zhong Lin Wang at Georgia Institute of Technology proposed the fundamental principle of this effect in 2010. [ 4 ] [ 5 ]
When a p-type semiconductor and a n-type semiconductor form a junction, the holes in the p-type side and the electrons in the n-type side tend to redistribute around the interface area to balance the local electric field , which results in a charge depletion layer . The diffusion and recombination of the electrons and holes in the junction region is closely related to the optoelectronic properties of the device, which is greatly affected by the local electric field distribution. The existence of the piezo-charges at the interface introduces three effects: a shift in local electronic band structure due to the introduced local potential, a tilt of the electronic band structure over the junction region for the polarization existing in the piezoelectric semiconductor, and a change in the charge depletion layer due to the redistribution of the local charge carriers to balance the local piezo-charges. The positive piezoelectric charges at the junction lower the energy band and the negative piezoelectric charges raise the energy band in n-type semiconductor region near the junction region. A modification in the local band by piezopotential may be effective for trapping charges so that the electron-hole recombination rate can be largely enhanced, which is very beneficial for improving the efficiency of a light-emitting diode . Furthermore, the inclined band tends to change the mobility of the carriers moving toward the junction.
The materials for piezo-phototronics should have three basic properties: piezoelectricity, semiconductor property, and photon excitation property [5]. Typical materials are the wurtzite structures, such as ZnO , GaN and InN . the three-way coupling among piezoelectricity, photoexcitation and semiconductor properties, which is the basis of piezotronics (piezoelectricity-semiconductor coupling), piezophotonics (piezoelectric-photon excitation coupling), optoelectronics, and piezo-phototronics piezoelectricity-semiconductor-photoexcitation). The core of these coupling relies on the piezopotential created by the piezoelectric materials.
Van der Waals heterostructures based on graphene and transition metal dichalcogenides (TMD) are promising for the realization of piezophototronic effect. [ 6 ] It has been shown that the photo-response of graphene/MoS 2 junction can be tuned by means of tensile stress manifesting piezophototronic effect in TMD devices. [ 6 ] | https://en.wikipedia.org/wiki/Piezophototronics |
Piezospectroscopy (also known as photoluminescence piezospectroscopy ) is an analytical technique that reveals internal stresses in alumina -containing materials, particularly thermal barrier coatings (TBCs). A typical procedure involves illuminating the sample with laser light of a known wavelength, causing the material to release its own radiation in response (see fluorescence ). By measuring the emitted radiation and comparing the location of the peaks to a stress-free sample, stresses in the material can be revealed without any destructive interaction. [ 1 ]
Piezospectroscopy can be used on any material that exhibits fluorescence , but is almost exclusively used on samples containing alumina because of the presence of chromium ions, either as part of the composition or as an impurity, that greatly increase the fluorescent response. As opposed to other methods of stress measurement, such as powder diffraction or the use of a strain gauge , piezospectroscopy can measure internal stresses at higher resolution, on the order of 1 μm, and can measure very quickly, with most systems taking less than one second to acquire data. [ 2 ]
Piezospectroscopy takes advantage of both the microstructure and composition of TBCs to generate accurate results.
A typical candidate for piezospectroscopy contains three layers: [ 3 ]
Coating failure is usually a result of spalling or cracking of the TGO layer. Because the TGO is buried beneath a thick layer of ceramic, subsurface stresses are generally difficult to detect. The use of an argon-ion laser makes this possible. The optical band gap (threshold for photon absorption) of the ceramic topcoat is much greater than the energy of argon laser light, effectively making the topcoat translucent and allowing for interaction with the TGO layer. [ 4 ] Within the TGO, it is the chromium (Cr 3+ ) ions that produce strong emission spectra and allow for piezospectroscopic analysis.
At the subatomic level, the laser light of known wavelength (usually 5149 Å ) causes the outer electron in the Cr 3+ ions to absorb the incoming radiation, which raises it to a higher energy level. Upon returning to a lower energy state, the electron releases its own radiation. Because the energy levels are discrete, the spectrum for stress-free aluminum oxide always exhibits two peaks at wavelengths 14,402 cm −1 and 14,432 cm −1 . The wavelength and frequency are related through:
v = c λ {\displaystyle v={c \over \lambda }}
where v is the frequency, λ is the wavelength, and c is the speed of light. If the coating is under a compressive stress, the peaks will be shifted downward while a tensile stress will shift them upward. [ 1 ]
The frequency shift is given by the equation:
Δ v = 2 3 ⨿ i i σ a v {\displaystyle \Delta v={2 \over 3}\amalg _{ii}\sigma _{av}}
where ⨿ i i {\displaystyle \amalg _{ii}} is the piezospectroscopic tensor and σ a v {\displaystyle \sigma _{av}} is the residual stress within the coating. [ 2 ]
In order to obtain accurate results, a few finely tuned instruments must work in tandem: [ 5 ]
A light source, such as a laser , is instrumental to piezospectroscopy. Narrow bandwidth lasers are preferred due to the increased resolution of the resulting spectrum. [ 6 ] The fluorescent response is stronger at lower frequencies, but excessively low frequency light can cause sample degradation and interference with the ceramic surface of the coating.
A microscope is generally used to isolate a certain section of a sample. Because TBC failure can begin at microscopic scales, magnification is often essential to accurately detect stresses. [ citation needed ]
A monochromator is used to filter out weakly scattered light and permit the strong emission peaks from the fluorescent response. In addition, notch or long-pass optical filters are used to filter the peak from the laser wavelength itself. [ citation needed ]
Many types of detectors are used with piezospectroscopy, the two most common being dispersion through a spectrograph or an interferometer . The resulting signal can be analyzed through Fourier Transform (FT) methods. Array detectors such as CCDs are also common, with many different types being suited for different ranges of wavelengths. [ citation needed ]
Piezospectroscopy is used in industry to ensure safe operation of TBCs. [ citation needed ]
It is critical that TBCs be applied properly in order to prevent premature microfractures, delamination, and other structural failure. [ 7 ] Through piezospectroscopy, parts can be put into service with the assurance of a properly protected substrate.
Piezospectroscopy can accurately describe the extent of any discovered damage and provide accurate lifetime estimates in actual use. In addition, piezospectroscopy can be set up in situ. [ 8 ] This, along with its noninvasive nature, makes piezospectroscopy an efficient method of onsite damage assessment. | https://en.wikipedia.org/wiki/Piezospectroscopy |
Piezotronics effect is using the piezoelectric potential (piezopotential) created in materials with piezoelectricity as a “gate” voltage to tune/control the charge carrier transport properties for fabricating new devices.
Neil A Downie showed how simple it was to build simple demonstrations on a macro-scale using a sandwich of piezoelectric material and carbon piezoresistive material to make an FET-like amplifying device and put it in a book of science projects for students in 2006. [ 1 ]
The fundamental principle of piezotronics was introduced by Prof. Zhong Lin Wang at Georgia Institute of Technology in 2007. [ 2 ] From 2006, a series of electronic devices have been demonstrated based on this effect, including piezopotential gated field-effect transistor , [ 3 ] piezopotential gated diode , [ 4 ] strain sensors , [ 5 ] force/flow sensors, [ 6 ] hybrid field-effect transistor , [ 7 ] piezotronic logic gates , [ 8 ] electromechanical memories , [ 9 ] etc.
Piezotronic devices are regarded as a new semiconductor-device category. Piezotronics is likely to have important applications in sensor , human-silicon technology interfacing, MEMS , nanorobotics and active flexible electronics.
Due to the non-central symmetry in materials such as the wurtzite structured ZnO , GaN and InN , a piezopotential is created in the crystal by applying a stress . Owing to the simultaneous possession of piezoelectricity and semiconductor properties, the piezopotential created in the crystal has a strong effect on the carrier transport process. [ 10 ]
Generally, the construction of the basic piezotronic devices can be divided into two categories. Here we use the nanowires as the example. The first kind is that the piezoelectric nanowire was put on a flexible substrate with two ends fixed by the electrodes. In this case, when the substrate is bended, the nanowire will be purely stretched or compressed. Piezopotential will be introduced along its axis. It will modify the electric field or the Schottky barrier (SB) height at the contact area. The induced positive piezopotential at one end will reduce the SB height, while the negative piezopotential at the other end will increase it. Thus the electric transport properties will be changed. The second kind of the piezotronic device is that one end of the nanowire is fixed with electrode, while the other end is free. In this case, when a force is applied at the free end of the nanowire to bend it, the piezopotential distribution will be perpendicular to the axis of the nanowire. The introduced piezoelectric field is perpendicular to electron transport direction, just like applying a gate voltage in the traditional field-effect transistor . Thus the electron transport properties will also be changed. [ 10 ]
The materials for piezotronics should be piezoelectric semiconductors, [ 10 ] such as ZnO, GaN and InN. Three-way coupling among piezoelectricity , photoexcitation and semiconductor is the basis of piezotronics (piezoelectricity-semiconductor coupling), piezophotonics (piezoelectric-photon excitation coupling), optoelectronics , and piezophototronics (piezoelectricity-semiconductor-photoexcitation). The core of these coupling relies on the piezopotential created by the piezoelectric materials. [ 10 ] | https://en.wikipedia.org/wiki/Piezotronics |
Piflufolastat ( 18 F) , sold under the brand name Pylarify among others, is a radioactive diagnostic agent used for positron emission tomography (PET) imaging . [ 1 ] [ 4 ] [ 5 ] It is given by intravenous injection. [ 1 ] [ 4 ]
The most common adverse reactions include headache, altered taste, and fatigue. [ 4 ]
Piflufolastat ( 18 F) was approved for medical use in the United States in May 2021. [ 1 ] [ 6 ] [ 4 ] It is the second PSMA-targeted PET imaging drug approved by the U.S. Food and Drug Administration (FDA). [ 4 ] The first approved PSMA-targeted PET imaging drug is Ga 68 PSMA-11 . [ 4 ]
Piflufolastat ( 18 F) is indicated for people with suspected prostate cancer metastasis (when cancer cells spread from the place where they first formed to another part of the body) who are potentially curable by surgery or other therapy. [ 1 ] [ 4 ] Piflufolastat ( 18 F) is also indicated for people with suspected prostate cancer recurrence based on elevated serum prostate-specific antigen (PSA) levels. [ 1 ] [ 4 ]
The safety and efficacy of piflufolastat ( 18 F) were evaluated in two prospective clinical trials (trial 1/NCT02981368 and trial 2/NCT03739684) with a total of 593 men with prostate cancer who each received one injection of piflufolastat ( 18 F). [ 4 ] [ 7 ] In the first trial, a cohort of 268 participants with biopsy-proven prostate cancer underwent PET/CT scans performed with piflufolastat ( 18 F). [ 4 ] These participants were candidates for surgical removal of the prostate gland and pelvic lymph nodes and were considered at higher risk for metastasis. [ 4 ] Among the participants who proceeded to surgery, those with positive readings in the pelvic lymph nodes on piflufolastat ( 18 F) PET had a clinically important rate of metastatic cancer confirmed by surgical pathology. [ 4 ]
The second trial enrolled 208 participants who had rising serum prostate-specific antigen levels after initial prostate surgery or other definitive therapy, and thus had biochemical evidence of recurrent prostate cancer. [ 4 ] Prior to a single piflufolastat ( 18 F) PET/CT scan, all of these participants had baseline conventional imaging performed that did not show definite spread of prostate cancer. [ 4 ] Piflufolastat ( 18 F) PET detected at least one positive lesion in at least one body region (bone, prostate bed, pelvic lymph node, other lymph nodes, or soft tissue) in 60% of these participants. [ 4 ] In participants with positive piflufolastat ( 18 F) PET readings who had correlative tissue pathology from biopsies, results from baseline or follow-up imaging by conventional methods, or serial PSA levels available for comparison, local recurrence or metastasis of prostate cancer was confirmed in an estimated 85% to 87% of cases, depending on the reader. [ 4 ] Thus, the second trial demonstrated that piflufolastat ( 18 F) PET can detect sites of disease in participants with biochemical evidence of recurrent prostate cancer, thereby providing important information that may impact the approach to therapy. [ 4 ]
Trial 1 included two groups of participants, some with recently diagnosed prostate cancer and others with suspicious findings on standard tests. [ 7 ] Trial 2 included participants who were treated for prostate cancer before, but there was suspicion that the cancer was spreading because of rising prostate-specific antigen. [ 7 ] Participants in trial 2 and the recently diagnosed participants in trial 1 were studied for effectiveness of piflufolastat ( 18 F), and all participants were studied for safety. [ 7 ] Trial 1 was conducted at eight sites in the United States and two sites in Canada, and trial 2 was conducted at thirteen sites in the United States and one site in Canada. [ 7 ] The number of participants representing efficacy findings may differ from the number of participants representing safety findings due to different pools of study participants analyzed for efficacy and safety. [ 7 ]
The US Food and Drug Administration (FDA) granted approval of Pylarify to Progenics Pharmaceuticals, Inc. [ 4 ]
This article incorporates public domain material from the United States Department of Health and Human Services | https://en.wikipedia.org/wiki/Piflufolastat_(18F) |
Pig-a gene mutation assay is a flow cytometry -based method for detecting mammalian cells that have inactivating mutations in the endogenous X-linked reporter gene called phosphatidyl inositolglycan class A gene ( PIG-A in humans and non-human primates, Pig-a in other mammalian species). PIG-A is involved in the synthesis of glycosylphosphatidylinositol (GPI), an anchor molecule that tethers multiple protein marker molecules at the surface of the cells. When the sample containing wild-type and PIG-A mutant cells is labeled with fluorescent antibodies raised against GPI-anchored protein markers (such as CD24 , CD48 , CD55 , CD59 ) the wild-type cells will fluoresce and PIG-A mutant cells will not. The fraction of non-fluorescent PIG-A mutant cells in the antibody-labeled sample can be efficiently determined on any of the modern high throughput flow cytometers. The PIG-A mutant frequency fraction can be determined with high accuracy within minutes by processing samples containing a total of a million cells or more.
Originally, PIG-A assay was proposed as a method for monitoring humans for somatic mutation. [ 1 ] The assay was developed as an extension of flow cytometric procedure for diagnosing human acquired genetic disorder, paroxysmal nocturnal hemoglobinuria (PNH). PIG-A assays were developed for cells of peripheral blood, such as red blood cells (RBCs) and white blood cells (WBCs). Due to conservative nature of GPI biosynthesis in mammalian species, similar flow cytometry protocols were developed for mammalian species of toxicological interest, i.e., mice and rats. [ 2 ] The most demanding RBC-based Pig-a assay requires only microliter volumes of peripheral blood which is easy to obtain without harming the animals. Therefore, the Pig-a assay can be added to various non-clinical in vivo safety evaluations mandated by regulatory authorities as a test measuring a value end-point, i.e., gene mutation, without requiring additional groups of animals for testing. Government agencies, such as t he US Food and Drug Administration and United States Environmental Protection Agency , require testing novel pharmaceuticals and high volume industrial chemicals for mutagenicity as a screen for potential carcinogens. An in vivo RBC Pig-a assay is an optional test for qualification of genotoxic impurities as described in FDA's ICH M7 guidance. [ 3 ] A standardized regulatory-compliant Test Guideline for performing Pig-a assay and interpreting the test results is being developed under the auspices of The Organisation for Economic Co-operation and Development . [ 4 ] | https://en.wikipedia.org/wiki/Pig-a_gene_mutation_assay |
Piggybacking on Internet access is the practice of establishing a wireless Internet connection by using another subscriber's wireless Internet access service without the subscriber's explicit permission or knowledge. It is a legally and ethically controversial practice, with laws that vary by jurisdiction around the world. While completely outlawed or regulated in some places, it is permitted in others.
A customer of a business providing hotspot service, such as a hotel or café , is generally not considered to be piggybacking, though non-customers or those outside the premises who are simply in reach may be. Many such locations provide wireless Internet access as a free or paid-for courtesy to their patrons or simply to draw people to the area. [ 1 ] Others near the premises may be able to gain access.
Piggybacking is distinct from wardriving , which involves only the logging or mapping of the existence of access points.
Piggybacking has become a widespread practice in the 21st century due to the advent of wireless Internet connections and wireless access points . Computer users who either do not have their own connections or who are outside the range of their own might find someone else's by wardriving or luck and use that one.
However, those residing near a hotspot or another residence with the service have been found to have the ability to piggyback off such connections without patronizing these businesses, which has led to more controversy. While some may be in reach from their own home or nearby, others may be able to do so from the parking lot of such an establishment, [ 2 ] from another business that generally tolerates the user's presence, or from the public domain. Others, especially those living in apartments or town houses , may find themselves able to use a neighbour's connection.
Wi-Fi hotspots, unsecured and secured, have been recorded to some degree with GPS-coordinates. Some sites host searchable databases or maps of the locations of user-submitted access points. The activity of finding and mapping locations has also been crowdsourced by many smartphone apps.
Long range antennas can be hooked up to laptop computers with an external antenna jack, which allows a user to pick up a signal from as far as several kilometers away. Since unsecured wireless signals can be found readily in most urban areas, laptop owners may find free or open connections almost anywhere. While 2.4 and 5 GHz antennas are commercially available and easily purchased from many online vendors, they are also relatively easy to make. Laptops and tablets that lack external antenna jacks can rely on external Wi-Fi network cards, many requiring only USB, which the laptop can itself easily provide from its own battery.
There are many reasons why Internet users desire to piggyback on other's networks.
For some, the cost of Internet service is a factor. Many computer owners who cannot afford a monthly subscription to an Internet service, who only use it occasionally, or who otherwise wish to save money and avoid paying, will routinely piggyback from a neighbour or a nearby business, or visit a location providing this service without being a paying customer. If the business is large and frequented by many people, this may go largely unnoticed.
Yet other piggybackers are regular subscribers to their own service, but are away from home when they wish to gain Internet access and do not have their own connection available at all or at an agreeable cost.
Often, a user will access a network completely by accident, as the network access points and computer's wireless cards and software are designed to connect easily by default. This is common when away from home or when the user's own network is not behaving correctly. Such users are often unaware that they are piggybacking, and the subscriber has not noticed. Regardless, piggybacking is difficult to detect unless the user can be viewed by others using a computer under suspicious circumstances.
Less often, it is used as a means of hiding illegal activities , such as downloading child pornography or engaging in identity theft . This is one main reason for controversy. [ 3 ]
Network owners leave their networks unsecured for a variety of reasons. They may desire to share their Internet access with their neighbours or the general public or may be intimidated by the knowledge and effort required to secure their network while making it available to their own devices. Some wireless networking devices may not support the latest security mechanisms, and users must therefore leave their network unsecured. For example, the Nintendo DS and Nintendo DS Lite can only access wireless routers using the discredited WEP standard, however, the Nintendo DSi and Nintendo 3DS both support WPA encryption. Given the rarity of such cases where hosts have been held liable for the activities of piggybackers, they may be unaware or unconcerned about the risks they incur by not securing their network, or of a need for an option to protect their network.
Some jurisdictions have laws requiring residential subscribers to secure their networks (e.g., in France "négligence caractérisée" in HADOPI ). Even where not required by law, landlords might request that tenants secure their networks as a condition of their lease. [ citation needed ]
Views on the ethics of piggybacking vary widely. Many support the practice by stating that it is harmless and benefits the piggybacker at no expense to others, but others criticize it with terms like "leeching," "mooching," or "freeloading." Different analogies are made in public discussions to relate the practice to more familiar situations. Advocates compare the practice to the following:
Opponents to piggybacking compare the practice to the following:
The piggybacker uses the connection paid for by another without sharing the cost. That is especially common in an apartment building in which many residents live within the normal range of a single wireless connection. Some residents can gain free Internet access while others pay. Many ISPs charge monthly rates, however, and so there is no difference in cost to the network owner.
Excessive piggybacking may slow the host's connection, with the host typically unaware of the reason for the reduction of speed . That is more of a problem if many persons are engaging in this practice, such as in an apartment or near a business.
Piggybackers may engage in illegal activity such as identity theft or child pornography without much of a trail to their own identity. That leaves network owners subject to investigation for crimes of which they are unaware. While persons engaging in piggybacking are generally honest citizens, a smaller number are breaking the law in that manner and so avoid identification by investigators. That, in particular, has led to some anti-piggybacking laws.
Some access points, when the factory default settings are used, are configured to provide wireless access to all who request it. Some commentators argue that those who set up access points without enabling security measures are offering their connection to the community. Many people intentionally leave their networks open to allow neighbours casual access, with some joining wireless community networks to share bandwidth freely. It has largely become good etiquette to leave access points open for others to use, just as someone expects to find open access points while on the road.
Jeffrey L. Seglin , an ethicist for the New York Times , recommends notifying network owners if they are identifiable, but he says there is nothing inherently wrong with accessing an open network and using the connection. "The responsibility for deciding whether others should be able to tap into a given access belongs squarely on the shoulders of those setting up the original connection." [ 5 ]
Similarly, Randy Cohen , the author of The Ethicist column for The New York Times Magazine and National Public Radio , says that one should attempt to contact the owner of a regularly used network and offer to contribute to the cost. However, he points out that network owners can easily password protect their networks and quotes the attorney Mike Godwin to conclude that open networks likely represent indifference on the part of the network owner and so accessing them is morally acceptable, if it is not abused. [ 6 ] [ 7 ]
The policy analyst Timothy B. Lee (not to be confused with Tim Berners-Lee [ 8 ] ) writes in the International Herald Tribune that the ubiquity of open wireless points is something to celebrate. He says that borrowing a neighbour's Wi-Fi is like sharing a cup of sugar, and leaving a network open is just being a good neighbour. [ 9 ]
Techdirt blogger Mike Masnick responded to an article in Time Magazine to express his disagreement with why a man was arrested for piggybacking a cafe's wireless medium. The man had been charged with breaking Title 18, Part 1, Chapter 47, of the United States Code , which states and includes anyone who "intentionally accesses a computer without authorization or exceeds authorized access." The writer himself is not sure what that title really means or how it applies to contemporary society since the code was established regarding computers and their networks during the Cold War era.
In the technical legality of the matter, Masnick believes the code was not broken because the access point owner did not secure the device specifically for authorized users. Therefore the device was implicitly placed into a status of "authorized." Lev Grossman , with Time Magazine , is on the side of most specialist and consumers, who believe the fault, if there is any, is mostly that of the network's host or owner.
An analogy commonly used in this arena of debate equates wireless signal piggybacking with entering a house with an open door. Both are supposed to be equatable, but the analogy is tricky, as it does not take into account unique differences regarding the two items in reference, which ultimately leave the analogy flawed.
The key to the flaw in the analogy is that with an unprotected access point, the default status is for all users to be authorized. An access point is an active device that initiates the announcement of its services and, if setup securely allows or denies authorization by its visitors.
A house door, on the other hand, has physical attributes that distinguish access to the house as authorized or unauthorized by its owner. Even with an open house door, it is plain whether one has been invited to that house by its owner and if entrance will be authorized or denied. A house owner's door is passive but has an owner who knows the risks of leaving their door open and house unprotected in the absence of the gate keeping presence. Equally, wireless access point owners should be aware that security risks exist when they leave their network unprotected. In that scenario, the owner has made the decision to allow the gatekeeper or access point to authorize all who attempt to connect because the gatekeeper was not told whom not to let in. [ 10 ] [ 11 ] [ 12 ] [ 13 ]
Laws do not have the physical ability to prevent such action from occurring, and piggybacking may be practiced with negligible detection.
The owner of any wireless connection has the ability to block access from outsiders by engaging wireless LAN security measures. Not all owners do so, and some security measures are more effective than others. As with physical security , choice is a matter of trade-offs involving the value of what is being protected, the probability of its being taken, and the cost of protection. An operator merely concerned with the possibility of ignorant strangers leeching Internet access may be less willing to pay a high cost in money and convenience than one who is protecting valuable secrets from experienced and studious thieves. More security-conscious network operators may choose from a variety of security measures to limit access to their wireless network, including:
Disabling SSID broadcasts has been recommended in the past as a security measure, although it only hides networks superficially. MAC addresses of routers are still broadcast, and can be detected using special means. But worse, a device that once connected to a hidden SSID will continuously transmit probe requests for this SSID and is vulnerable to the Evil Twin attack . Therefore, SSID hiding can no longer be considered a security measure.
There are several alternatives to piggybacking. Internet access is available on many data plans for smartphones and PDAs . Although it may have browsing limitations compared with Internet access from traditional Internet service providers for desktop or laptop computers, the Internet can be accessed anywhere there is an adequately strong data signal. Some mobile phone service providers offer mobile Internet service to other devices via a data connection from the mobile phone. Also known as tethering , one can interface to their phone either wirelessly using Bluetooth or Wi-Fi or wired via cable allowing access to the Internet anywhere there is a cell network signal.
Many jurisdictions have been experimenting with statewide, province-wide, county-wide or municipal wireless network access. On September 20, 2005, Google WiFi was announced as a municipal wireless mesh network in Mountain View, California . Baltimore County, Maryland provides free Wi-Fi access at government offices, libraries, and county facilities. [ 15 ] This service was first provided in May 2007 in the central business district of the county seat, Towson , and gradually expanded throughout the remainder of the county. [ 16 ] When the service was expanded to more public areas in 2014, Baltimore's acting chief technology officer, L. Jerome Mullen, remarked, "Projects like this are just the beginning of the opportunities that remain as we strengthen and expand the City's fiber optic network. We are building digital city infrastructure, and the possibilities are endless." [ 17 ] In New York City , the Department of Parks and Recreation provides free Wi-Fi in parks across the city. [ 18 ] BAI Communications was contracted by municipal public transportation authorities to install free Wi-Fi in underground subway stations in Toronto , Canada [ 19 ] and in all 279 Manhattan, Queens, and Bronx underground subway stations in New York City. [ 20 ] On January 8, 2013, Google and the Chelsea Improvement Company , a local public advocacy group, announced that they would install free Wi-Fi in the New York City neighborhood of Chelsea . New York Senator Chuck Schumer said at the press conference, "It's not very expensive at all—just a smidgeon of what Sandy cost. The mayor and I said maybe we could get this done for all of New York. We look forward to the day when all of New York has free Wi-Fi." [ 21 ] On November 17, 2014, the mayor of New York City, Bill de Blasio , announced LinkNYC , an infrastructure project to create a free, encrypted, gigabit wireless network to cover New York City by replacing the city's payphones with Wi-Fi hotspots and web browser kiosks where free phone calls could also be made. These pilot programs may result in similar services being launched and interconnected nationwide.
Free Internet access hotspots have also been opened by a wide range of organisations. Companies sell hardware and network management services to establish hotspots. Other hotspot-based efforts have been launched with the intention of providing global, low-cost or free Internet access. Fon is a wireless router vendor which allows owners of its routers to share Internet access with other owners of Fon routers. Users who do not own a Fon router can also connect at a small price. Guifi.net is a free, open, international telecommunications community network organized and expanded by individuals, companies and administrations. On November 27, 2012, the Electronic Frontier Foundation and a coalition of nine other groups launched OpenWireless.org , an Internet activism project which seeks to increase Internet access by encouraging individuals and organisations to configure their wireless routers to offer a separate public wireless guest network or to open their network completely. [ 22 ] | https://en.wikipedia.org/wiki/Piggybacking_(Internet_access) |
In decision theory , a pignistic probability is a probability that a rational person will assign to an option when required to make a decision.
A person may have, at one level certain beliefs or a lack of knowledge, or uncertainty, about the options and their actual likelihoods. However, when it is necessary to make a decision (such as deciding whether to place a bet ), the behaviour of the rational person would suggest that the person has assigned a set of regular probabilities to the options. These are the pignistic probabilities .
The term was coined by Philippe Smets , [ 1 ] and stems from the Latin pignus , a bet. He contrasts the pignistic level, where one might take action, with the credal level, where one interprets the state of the world:
A pignistic probability transform [ 2 ] will calculate these pignistic probabilities from a structure that describes belief structures. | https://en.wikipedia.org/wiki/Pignistic_probability |
A pile cap is a thick concrete mat that rests on concrete or timber piles that have been driven into soft or unstable ground to provide a suitable stable foundation. It usually forms part of the deep foundation of a building, typically a multi-story building, structure or support base for heavy equipment, or of a bridge. The cast concrete pile cap distributes the load of the building into the piles . A similar structure to a pile cap is a "raft", which is a concrete foundation floor resting directly onto soft soil which may be liable to subsidence . [ 1 ]
The mat is made of concrete which is an aggregate of small rocks and cement . This mixture has to be supported by a framework to avoid sagging and fracture while setting. This process is known as shuttering and reinforcing . The materials used are long steel bars with longitudinal protrusions between the piles held in shape by thinner tie wires. Once this steel mat is laid, timber is attached around the perimeter to contain the wet concrete mixture. Once poured, (usually as a series of small loads), the concrete is stirred to remove any air pockets that might weaken the structure when set. The concrete undergoes a chemical change as it hardens and this produces a lot of heat. Sometimes, if the mass of concrete is very large, pipes carrying refrigerant coolant are used in the mass to assist the setting process to prevent the concrete from cracking. [ 2 ]
This engineering-related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pile_cap |
A pile driver is a heavy-duty tool used to drive piles into soil to build piers, bridges, cofferdams , and other "pole" supported structures, and patterns of pilings as part of permanent deep foundations for buildings or other structures. Pilings may be made of wood, solid steel, or tubular steel (often later filled with concrete), and may be driven entirely underwater/underground, or remain partially aboveground as elements of a finished structure.
The term "pile driver" is also used to describe members of the construction crew associated with the task, [ 1 ] also colloquially known as "pile bucks". [ 2 ]
The most common form of pile driver uses a heavy weight situated between vertical guides placed above a pile. The weight is raised by some motive power (which may include hydraulics , steam , diesel , electrical motor, or manual labor). At its apex the weight is released, impacting the pile and driving it into the ground. [ 1 ] [ 3 ]
There are a number of claims to the invention of the pile driver. A mechanically sound drawing of a pile driver appeared as early as 1475 in Francesco di Giorgio Martini 's treatise Trattato di Architectura . [ 4 ] Also, several other prominent inventors— James Nasmyth (son of Alexander Nasmyth ), who invented a steam-powered pile driver in 1845, [ 5 ] watchmaker James Valoué , [ 6 ] Count Giovan Battista Gazzola , [ 7 ] and Leonardo da Vinci [ 8 ] —have all been credited with inventing the device. However, there is evidence that a comparable device was used in the construction of Crannogs at Oakbank and Loch Tay in Scotland as early as 5000 years ago. [ 9 ] In 1801 John Rennie came up with a steam pile driver in Britain. [ 10 ] Otis Tufts is credited with inventing the steam pile driver in the United States . [ 11 ]
Ancient pile driving equipment used human or animal labor to lift weights, usually by means of pulleys , then dropping the weight onto the upper end of the pile. Modern piledriving equipment variously uses hydraulics, steam, diesel, or electric power to raise the weight and guide the pile.
A modern diesel pile hammer is a large two-stroke diesel engine. The weight is the piston , and the apparatus which connects to the top of the pile is the cylinder. Piledriving is started by raising the weight; usually a cable from the crane holding the pile driver — This draws air into the cylinder. Diesel fuel is injected into the cylinder. The weight is dropped, using a quick-release. The weight of the piston compresses the air/fuel mixture, heating it to the ignition point of diesel fuel. The mixture ignites, transferring the energy of the falling weight to the pile head, and driving the weight up. The rising weight draws in fresh air, and the cycle continues until the fuel is depleted or is halted by the crew. [ 12 ]
From an army manual on pile driving hammers:
The initial start-up of the hammer requires that the piston (ram) be raised to a point where the trip automatically releases the piston, allowing it to fall. As the piston falls, it activates the fuel pump, which discharges a metered amount of fuel into the ball pan of the impact block. The falling piston blocks the exhaust ports, and compression of fuel trapped in the cylinder begins. The compressed air exerts a pre-load force to hold the impact block firmly against the drive cap and pile. At the bottom of the compression stroke, the piston strikes the impact block, atomizing the fuel and starting the pile on its downward movement. In the instant after the piston strikes, the atomized fuel ignites, and the resulting explosion exerts a greater force on the already moving pile, driving it further into the ground. The reaction of the explosion rebounding from the resistance of the pile drives the piston upward. As the piston rises, the exhaust ports open, releasing the exhaust gases to the atmosphere. After the piston stops its upward movement, it again falls by gravity to start another cycle.
Vertical travel leads come in two main forms: spud and box lead types. Box leads are very common in the Southern United States and spud leads are common in the Northern United States, Canada and Europe.
A hydraulic hammer is a modern type of piling hammer used instead of diesel and air hammers for driving steel pipe, precast concrete , and timber piles. Hydraulic hammers are more environmentally acceptable than older, less efficient hammers as they generate less noise and pollutants. In many cases the dominant noise is caused by the impact of the hammer on the pile, or the impacts between components of the hammer, so that the resulting noise level can be similar to diesel hammers. [ 12 ]
Hydraulic press-in equipment installs piles using hydraulic rams to press piles into the ground. This system is preferred where vibration is a concern. There are press attachments that can adapt to conventional pile driving rigs to press 2 pairs of sheet piles simultaneously. Other types of press equipment sit atop existing sheet piles and grip previously driven piles. This system allows for greater press-in and extraction force to be used since more reaction force is developed. [ 12 ] The reaction-based machines operate at only 69 dB at 23 ft allowing for installation and extraction of piles in close proximity to sensitive areas where traditional methods may threaten the stability of existing structures.
Such equipment and methods are specified in portions of the internal drainage system in the New Orleans area after Hurricane Katrina , as well as projects where noise, vibration and access are a concern.
Vibratory pile hammers contain a system of counter-rotating eccentric weights, powered by hydraulic motors, and designed so that horizontal vibrations cancel out, while vertical vibrations are transmitted into the pile. The pile driving machine positioned over the pile with an excavator or crane, and is fastened to the pile by a clamp and/or bolts. Vibratory hammers can drive or extract a pile. Extraction is commonly used to recover steel I-beams used in temporary foundation shoring. Hydraulic fluid is supplied to the driver by a diesel engine-powered pump mounted in a trailer or van, and connected to the driver head via hoses. When the pile driver is connected to a dragline excavator , it is powered by the excavator's diesel engine. Vibratory pile drivers are often chosen to mitigate noise, as when the construction is near residences or office buildings, or when there is insufficient vertical clearance to permit use of a conventional pile hammer (for example when retrofitting additional piles to a bridge column or abutment footing). Hammers are available with several different vibration rates, ranging from 1200 vibrations per minute to 2400 VPM. The vibration rate chosen is influenced by soil conditions and other factors, such as power requirements and equipment cost.
A piling rig is a large track-mounted drill used in foundation projects which require drilling into sandy soil, clay, silty clay, and similar environments. Such rigs are similar in function to oil drilling rigs, and can be equipped with a short screw (for dry soil), rotary bucket (for wet soil) or core drill (for rock), along with other options. Expressways, bridges, industrial and civil buildings, diaphragm walls, water conservancy projects, slope protection, and seismic retrofitting are all projects which may require piling rigs.
The underwater sound pressure caused by pile-driving may be deleterious to nearby fish. [ 13 ] [ 14 ] State and local regulatory agencies manage environment issues associated with pile-driving. [ 15 ] Mitigation methods include bubble curtains , balloons, internal combustion water hammers. [ 16 ] | https://en.wikipedia.org/wiki/Pile_driver |
Pileup format is a text-based format for summarizing the base calls of aligned reads to a reference sequence. This format facilitates visual display of SNP /indel calling and alignment. It was first used by
Tony Cox and Zemin Ning at the Wellcome Trust Sanger Institute , and became widely known through its implementation within the SAMtools software suite. [ 1 ]
Each line consists of 5 (or optionally 6) tab-separated columns:
This is an optional column. If present, the ASCII value of the character minus 33 gives the mapping Phred quality of each of the bases in the previous column 5. This is similar to quality encoding in the FASTQ format .
There is no standard file extension for a Pileup file, but .msf (multiple sequence file), .pup [ 2 ] and .pileup [ 3 ] [ 4 ] are used. | https://en.wikipedia.org/wiki/Pileup_format |
The pileus ( Ancient Greek : πῖλος , pîlos ; also pilleus or pilleum in Latin ) was a brimless felt cap worn in Ancient Greece , Etruria , Illyria (especially Pannonia ), [ 1 ] [ 2 ] [ 3 ] [ 4 ] later also introduced in Ancient Rome . [ 5 ] The pileus also appears on Apulian red-figure pottery .
The pilos together with the petasos were the most common types of hats in Archaic and Classical era (8th–4th century BC) Greece. [ 6 ] In the 5th century BC, a bronze version began to appear in Ancient Greece and it became a popular infantry helmet. It occasionally had a horsehair crest. [ 7 ] The Greek pilos resembled the Roman and Etruscan pileus, which were typically made of felt. [ 8 ] The Greek πιλίδιον ( pilidion ) and Latin pilleolus were smaller versions, similar to a skullcap .
Similar caps were worn in later antiquity and the early medieval ages in various parts of Europe, as seen in Gallic and Frankish dress. [ 8 ] The Albanian traditional felt cap, the plis , worn today in Albania , Kosovo and adjacent areas, originated from a similar felt cap worn by the ancient Illyrians .
A pointed version called pileus cornutus served as a distinguishing sign for the Jewish people in the Holy Roman Empire for five centuries (12th–17th centuries). [ 9 ]
The word for the cap in antiquity was pil(l)eus or pilos , indicating a kind of felt. [ 10 ] Greek πῖλος pilos , Latin pellis , Albanian plis , as well as Old High German filiz and Proto-Slavic *pьlstь are considered to come from a common Proto-Indo-European root meaning "felt". [ 11 ]
The pilos ( Greek : πῖλος, felt [ 12 ] ) was a typical conical hat in Ancient Greece among travelers, workmen and sailors, though sometimes a low, broad-rimmed version was also preferred, known as petasos . [ 13 ] It could be made of felt or leather. The pilos together with the petasos were the most common types of hats in Archaic and Classical era (8th–4th century B.C.) Greece. [ 6 ]
Pilos caps often identify the mythical twins, or Dioscuri, Castor and Pollux , as represented in sculptures, bas-reliefs and on ancient ceramics. Their caps were supposedly the remnants of the egg from which they hatched. [ 14 ] The pilos appears on votive figurines of boys at the sanctuary of the Cabeiri at Thebes , the Cabeirion . [ 15 ]
In warfare, the pilos type helmet was often worn by the peltast light infantry, in conjunction with the exomis , but it was also worn by the heavy infantry. [ citation needed ]
In various artistic depictions in the middle Byzantine period soldiers are seen wearing pilos caps. [ 16 ]
From the 5th century B.C the Greeks developed the pilos helmet which derived from the hat of the same name. [ 17 ] This helmet was made of bronze in the same shape as the pilos which was presumably sometimes worn under the helmet for comfort, giving rise to the helmet's conical shape. [ 18 ] Some historians theorize that the pilos helmet had widespread adoption in some Greek cities such as Sparta , [ 19 ] [ 4 ] however, there is no primary historical source or any archeological evidence that would suggest that Sparta or any other Greek state would have used the helmet in a standardized fashion for their armies. What led historians to believe that the helmet was widespread in places such as Sparta was, amongst other reasons, the supposed advancement of battlefield tactics that required that infantry have full vision and mobility. [ 19 ] However, many other types of Greek helmet offered similar designs to the pilos when it came to visibility, such as the konos or the chalcidian helmets.
Being of Greek origin the Pilos helmet was worn in the late Etruscan Period by the local armies in the region. [ 20 ]
A so-called "Illyrian cap" was also known as "Panonian pileus" in the period of the Tetrarchy. [ 1 ] As such during the period of the Emperor-soldiers the influences of the Illyrian provinces of the Roman Empire were evident, such as the wide use of the Pannonian pileus. [ 3 ]
The Albanian traditional felt cap ( Albanian : plis , cognate of pilos [ 11 ] and pileus ) originated from a similar felt cap worn by the Illyrians . [ 21 ] [ 22 ] The 1542 Latin dictionary De re vestiaria libellus, ex Bayfio excerptus equated an Albanian hat with a kyrbasia , and described it as a "tall pileus [hat] in the shape of a cone" ( pileus altus in speciem coni eductus ). [ 23 ]
An Illyrian wearing a pileus has been hesitantly identified on a Roman frieze from Tilurium in Dalmatia; the monument could be part of a trophy base erected by the Romans after the Great Illyrian Revolt (6–9 BCE). [ 24 ]
A cylindrical flat-topped felt cap made of fur or leather originated in Pannonia, and came to be known as the Pannonian cap ( pileus pannonicus ). [ 25 ] [ 10 ] [ 26 ] [ 3 ] [ 1 ]
The Roman pileus resembled the Greek pilos and was often made of felt. [ 8 ] In Ancient Rome , a slave was freed in a ceremony in which a praetor touched the slave with a rod called a vindicta and pronounced him to be free. The slave's head was shaved and a pileus was placed upon it. Both the vindicta and the cap were considered symbols of Libertas , the goddess representing liberty. [ 27 ]
The rod and hat were part of a legal ritual of manumission . A 3rd-party adsertor libertatis (liberty asserter, neither slaver or enslaved) would state: Hunc Ego hominem ex jure Quiritum liberum esse aio (I declare this man is free) while using the "vindicta" (one of multiple manumission types). The legal ritual was explicitly designed to be anti-slavery in the interest of self-empowerment of all members of society, even those legally unable to pursue it directly e.g. the enslaved, and to guarantee that liberty was permanent. [ 28 ]
One 19th-century dictionary of classical antiquity states that, "Among the Romans the cap of felt was the emblem of liberty. When a slave obtained his freedom he had his head shaved, and wore instead of his hair an undyed pileus." [ 29 ] Hence the phrase servos ad pileum vocare is a summons to liberty, by which slaves were frequently called upon to take up arms with a promise of liberty ( Liv. XXIV.32). The figure of Liberty on some of the coins of Antoninus Pius , struck A.D. 145, holds this cap in the right hand. [ 30 ]
In the period of the Tetrarchy , the Pannonian cap ( pileus pannonicus ) was adopted as the main military cap of the Roman army, until the 6th century AD; it was worn by lightly armed or off-duty soldiers, as well as workmen. [ 2 ] [ 3 ] [ 10 ] It often appears in Roman artwork, in particular mosaics, from the late 3rd century AD. The earliest preserved specimen of the hat was found at the Roman quarry of Mons Claudianus , in the eastern desert of Egypt , and is dated to 100–120 AD; it has a dark-green color, and looks like a low fez or pillbox hat . [ 10 ] [ 31 ]
Similar caps were worn in later antiquity and the early medieval ages in various parts of Europe, as seen in Gallic and Frankish dress, in particular of the Merovingian and Carolingian era. [ 8 ] | https://en.wikipedia.org/wiki/Pileus_(hat) |
In mycology (the branch of biology that includes the study of mushrooms and other fungi ), the pileus is the technical name for the cap, or cap-like part, of a basidiocarp or ascocarp ( fungal fruiting body ) that supports a spore-bearing surface, the hymenium. [ 1 ] The hymenium ( hymenophore ) may consist of lamellae , tubes, or teeth, on the underside of the pileus. A pileus is characteristic of agarics , boletes , some polypores , tooth fungi , and some ascomycetes .
Pilei can be formed in various shapes, and the shapes can change over the course of the developmental cycle of a fungus. The most familiar pileus shape is hemispherical or convex. Convex pilei often continue to expand as they mature until they become flat. Many well-known species have a convex pileus, including the button mushroom , various Amanita species and boletes .
Some, such as the parasol mushroom , have distinct bosses or umbos and are described as umbonate . An umbo is a knobby protrusion at the center of the cap. Some fungi, such as chanterelles have a funnel- or trumpet -shaped appearance. In these cases the pileus is termed infundibuliform . | https://en.wikipedia.org/wiki/Pileus_(mycology) |
Pilish is a style of constrained writing in which the lengths of consecutive words or sentences match the digits of the number π ( pi ). [ 1 ] [ 2 ] The shortest example is any three-letter word, such as "hat", but many longer examples have been constructed, including sentences, poems, and stories.
The following sentence is an example which matches the first fifteen digits of π :
How I need a drink, alcoholic of course, after the heavy lectures involving quantum mechanics!
The following Pilish poem (written by Joseph Shipley ) matches the first 31 digits of π:
A full-length Pilish novel has been published, Not A Wake by Mike Keith [ 1 ] [ 3 ] which currently holds the record of the longest Pilish text with 10,000 digits represented. [ 4 ]
In order to deal with occurrences of the digit zero, the following rule set was introduced (referred to as Basic Pilish ):
Since long runs of small non-zero digits are difficult to deal with naturally (such as 1121 or 1111211), another rule set called Standard Pilish was introduced:
Cadae is a poetry form similar to the fib , but based on π . The word "cadae" is the alphabetical equivalent of the first five digits of π , 3.1415. [ 5 ]
The form of a cadae is based on pi on two levels. There are five stanzas, with 3, 1, 4, 1, and 5 lines each, respectively for a total of fourteen lines in the poem. Each line of the poem also contains an appropriate number of syllables. The first line has three syllables, the second has one, the third has four, and so on, following the sequence of pi as it extends infinitely. [ 6 ]
Rachel Hommel wrote an untitled "Cadaeic Cadae", which uses the cadaeic form as explained above, and adds a level of complexity to it wherein the number of letters in each word represents a digit of pi. [ 7 ]
For his book, "The Burning Door," Tony Leuzzi wrote a series of 33 untitled poems in cadaeic form. [ 8 ]
" Cadaeic Cadenza " is a 1996 short story by Mike Keith . It is an example of cadae and pilish; a cadenza is a solo passage in music. In addition to the main restriction, the author attempts to mimic portions, or entire works, of different types and pieces of literature (" The Raven ", " Jabberwocky ", the lyrics of Yes , " The Love Song of J. Alfred Prufrock ", Rubaiyat , Hamlet , and Carl Sandburg 's Grass ) in story, structure, and rhyme.
Some sections of the poem use words of more than ten letters as a one followed by another digit:
where 11 represents two consecutive digit "1"s in pi.
The first part of Cadaeic Cadenza is slightly changed from an earlier version, "Near a Raven", which was a retelling of Edgar Allan Poe 's " The Raven ". [ 9 ] The text of poem begins: [ 10 ]
Poe, E. Near a Raven Midnights so dreary, tired and weary, Silently pondering volumes extolling all by-now obsolete lore. During my rather long nap - the weirdest tap! An ominous vibrating sound disturbing my chamber's antedoor. "This", I whispered quietly, "I ignore".
2. Walkowicz, Nathan (2021) Stile: “An Infinite Mystery” Kindle Direct Publishing. ISBN 979-8485105631 | https://en.wikipedia.org/wiki/Pilish |
The Pill of Immortality , also known as xiandan (仙丹), jindan (金丹) or dan (丹) in general, was an elixir or pill sought by Chinese alchemists to confer physical or spiritual immortality. It is typically represented as a spherical pill of dark color and uniform texture, made of refined medical material. Colloquially and in Chinese medicine , the term can also refer to medicine of great efficacy.
The search for the pill was started several centuries BC ago and continued until 500 AD and was often based on noble metals such as mercury and gold . [ 1 ] Its search was supported by the emperors and the nobility of China, with a strong tradition in Taoism. [ 2 ] [ 3 ] During the Qin dynasty , the founding Emperor Qin Shi Huang consulted sages and alchemists to seek such a pill to achieve eternal life.
The alchemical tradition in China was divided into two differing schools in the search for the pill of immortality. [ 4 ] Taoist sects which advocated the attainment of immortality by consuming substances were very popular during the Eastern Han dynasty in the 2nd century AD and they were collectively known as the school of the "external pill", or Waidan (外丹). [ 5 ] By contrast, "internal alchemy", or Neidan (内丹), was thought to create an immortal body within the corporeal body, and a variety of actions involving dietary, respiratory, and sexual practices and/or mental practices such as meditation were believed to cause immortality.
The writings of the Liexian Zhuan describes a man named Wei Boyang who had made such a pill of immortality. [ 6 ]
Texts dating from the 4th century AD and later present the Yellow Emperor near the end of his reign as finding the pill in the Huang Shan mountain range, then establishing the seventy-two peaks of the mountains as the dwelling place for the immortals. [ 7 ] | https://en.wikipedia.org/wiki/Pill_of_Immortality |
Pillars of Creation is a photograph taken by the Hubble Space Telescope that depicts elephant trunks of interstellar gas and dust in the Eagle Nebula of the Serpens constellation, some 6,500–7,000 light-years (2,000–2,100 pc; 61–66 Em) from Earth. [ 1 ] These elephant trunks had been discovered by John Charles Duncan in 1920 on a plate made with the Mount Wilson Observatory 60-inch telescope . [ 2 ] [ 3 ] They are so named because the gas and dust are in the process of creating new stars, while also being eroded by the light from nearby stars that have recently formed. [ 4 ]
Taken on April 1, 1995, it was named one of the top ten photographs from Hubble by Space.com . [ 5 ] The astronomers responsible for the photo were Jeff Hester and Paul Scowen from Arizona State University . The region was rephotographed by ESA 's Herschel Space Observatory in 2011, again by Hubble in 2014 with a newer camera, and the James Webb Space Telescope in 2022.
Released in 2007, Chandra X-ray Observatory (AXAF) had observed the area in 2001. It did not find many X-ray sources in the towers but was able to observe sources at various X-ray energy levels in the area from young stars. [ 6 ]
The image is noted for its global culture impact, being considered the most iconic picture taken by the Hubble Space Telescope [ 7 ] and National Geographic noting on its 20th anniversary that the image had been featured on everything from "t-shirts to coffee-mugs". [ 8 ]
The name is based on a phrase used by Charles Spurgeon in his 1857 sermon "The Condescension of Christ": [ 9 ]
In calling the Hubble's spectacular new image of the Eagle Nebula the Pillars of Creation , NASA scientists were tapping a rich symbolic tradition with centuries of meaning, bringing it into the modern age. As much as we associate pillars with the classical temples of Greece and Rome, the concept of the pillars of creation – the very foundations that hold up the world and all that is in it – reverberates significantly in the Christian tradition. When William Jennings Bryan published The World's Famous Orations in 1906, he included an 1857 sermon by London pastor Charles Haddon Spurgeon titled "The Condescension of Christ". In it, Spurgeon uses the phrase to convey not only the physical world but also the force that keeps it all together, emanating from the divine: "And now wonder, ye angels," Spurgeon says of the birth of Christ, "the Infinite has become an infant; he, upon whose shoulders the universe doth hang, hangs at his mother's breast; He who created all things, and bears up the pillars of creation, hath now become so weak, that He must be carried by a woman!"
The pillars are composed of cool molecular hydrogen and dust that are being eroded by photoevaporation from the ultraviolet light of relatively close and hot stars . The leftmost pillar is about four light-years in length. [ 10 ] The finger-like protrusions at the top of the clouds are larger than the Solar System , and are made visible by the shadows of evaporating gaseous globules (EGGs), which shield the gas behind them from intense UV flux. [ 11 ] EGGs are themselves incubators of new stars. [ 12 ] The stars then emerge from the EGGs, which then are evaporated.
Images taken with the Spitzer Space Telescope uncovered a cloud of dust in the vicinity of the Pillars of Creation that hypothetically could be a shock wave produced by a supernova . [ 13 ] The appearance of the cloud suggests the supernova shockwave would have destroyed the Pillars of Creation 6,000 years ago. Given the distance of roughly 7,000 light-years between Earth and the Pillars of Creation, this would mean that they have actually already been destroyed, but because light travels at a finite speed , this destruction should be visible from Earth in about 1,000 years. [ 14 ]
This interpretation of the hot dust has been disputed by an astronomer uninvolved in the Spitzer observations, who argues that a supernova should have resulted in stronger radio and x-ray radiation than has been observed, and that winds from massive stars could instead have heated the dust. If this is the case, the Pillars of Creation will undergo a more gradual erosion. [ 15 ]
Hubble's photo of the pillars is composed of 32 different images [ 16 ] from four CCD sensors [ 17 ] in the Wide Field and Planetary Camera 2 on board Hubble. [ 18 ] The photograph was made with light emitted by different elements in the cloud and appears as a different color in the composite image: green for hydrogen , red for singly ionized sulfur and blue for double-ionized oxygen atoms. [ 4 ]
The "stair-shaped" [ 17 ] missing part of the picture at the top right corner originates from the fact that the camera for the top-right quadrant has a magnified view; when its images are scaled down to match the other three cameras, there is necessarily a gap in the rest of that quadrant. [ 17 ] This effect is also present on other WFPC2 images, and can be displayed at any corner depending on how the image has been re-oriented for publication. [ 19 ]
The Wide Field and Planetary Camera 2 was replaced by the Wide Field Camera 3 , and the former was taken back to Earth where it is displayed in a museum. It was replaced in 2009 as part of a Space Shuttle mission ( STS-125 ).
In 2010 Herschel Space Observatory captured a new image of the Pillars of Creation in far-infrared wavelengths, which allows astronomers to look inside the pillars and structures in the region, and come to a much fuller understanding of the creative and destructive forces inside the Eagle Nebula. [ 20 ]
In celebration of the 25th anniversary since the launch of the Hubble Space Telescope, astronomers assembled a larger and higher-resolution photograph of the Pillars of Creation which was unveiled in January 2015 at the American Astronomical Society meeting in Seattle. The image was photographed by the Hubble Telescope's Wide Field Camera 3 , installed in 2009, in visible light . An infrared image was also taken. [ 21 ] The re-imaging has a wider view that shows more of the base of the nebulous columns. [ 8 ]
In October 2022, it was unveiled that the James Webb Space Telescope captured a new image of the Pillars of Creation utilizing the NIRCam aboard the spacecraft. The image was able to capture ejections from the formation of young stars still in development in great detail, as seen by the red spots near the edges of the pillars. [ 22 ] [ 23 ]
The most recent visualization of the Pillars of Creation was released by NASA in June 2024. [ 24 ] It is a 3D rendering created by images from both the James Webb Space Telescope and the Hubble Space Telescope. NASA described it as "the most comprehensive and detailed multiwavelength movie yet of this star-birthing region." [ 25 ] | https://en.wikipedia.org/wiki/Pillars_of_Creation |
Pillow-plate heat exchangers are a class of fully welded heat exchanger design, which exhibit a wavy, “pillow-shaped” surface formed by an inflation process. Compared to more conventional equipment, such as shell and tube and plate and frame heat exchangers , pillow plates are a quite young technology. Due to their geometric flexibility, they are used as well as “plate-type” heat exchangers and as jackets for cooling or heating of vessels. Pillow plate equipment is currently experiencing increased attention and implementation in process industry.
Pillow plates are manufactured by an inflation process, where two thin metal sheets are spot-welded to each other over the entire surface by laser or resistance welding . The sides of the plates are sealed by seam welding, other than the connecting ports. Finally, the gap between the thin metal sheets is pressurized by a hydraulic fluid causing a plastic forming of the plates, which eventually leads to their characteristic wavy surface.
In principle, there are two different types of pillow plates: single-embossed and double-embossed. The former commonly form the double walls of jacketed vessels , while the latter are assembled to a stack (bank) to manufacture pillow plate heat exchangers. Single-embossed pillow plates are formed when the base plate is significantly thicker than the top plate. The thinner top plate deforms, while the base plate remains plane.
Furthermore, pillow plates are commonly equipped with “baffle” seam weldings, which offer a targeted flow guidance in the pillow plate channels in cases, where flow distribution or fluid velocity might be an issue. A method for obtaining flow guidance by baffles in the channels between adjacent pillow plates in pillow plate heat exchangers, has recently been proposed in. [ 1 ]
Due to their construction, pillow plates are hermetically sealed, they have a high structural stability and their manufacturing is mostly automated and highly flexible. Pillow plates can be operated at pressures > 100 MPa [ citation needed ] and temperatures of up to 800 °C.
The application of pillow plates is very extensive, due to their favorable properties such as high geometric flexibility and good adaptivity to almost every process. Their implementation depends on their underlying construction, i.e. pillow plate banks or pillow plate jacketed tanks. The relatively flat external surface is easy to clean and suitable for high fouling or sanitary applications, but the internal surface has fine seams around each spot weld and is not easy to clean, therefore the internal surface is only suitable for non-fouling fluids like water, steam or refrigerants.
Pillow plate banks are typically used in applications involving liquid-liquid, gas-liquid, high viscosity or dirty media, low pressure loss requirements, condensation (e.g. top condensers), falling film evaporation (e.g. paper & pulp industry), reboilers , water chilling, drying of solids, flake ice generation (food industry) and more. They are also commonly used as immersion chillers (e.g. in electroplating ), where the banks are immersed directly into the tank. Banks can be constructed to allow the individual plates to be separated from the stack, allowing easy cleaning or maintenance.
The most extensive application of pillow plates to date is with jacketed vessels , because of their flexibility, full surface area coverage for heat transfer, low fluid hold-up, favorable manufacturing costs & time, and easy cleaning, especially in sterile applications. The tanks can be equipped with multiple jackets over its surface, including also the tank bottom, e.g. conical or dished , and can include additional cylindrical shells inside the tank. Typical areas of implementation of pillow plate jacketed tanks are in food and beverage industry and in chemical and pharmaceutical industry. These jackets are also referred to as "dimple jackets".
Due to their geometrical flexibility, pillow plates can be customized/adapted to almost any geometry to offer targeted heat transfer where it is needed. Some examples are cooling of pipes in thermal processes or even battery packs and electric motors for electric vehicles in automotive industry.
In contrast to more conventional heat exchangers, knowledge of thermohydraulic performance of pillow plates and experience with their design is limited. To overcome this bottleneck efforts are currently being made to develop commercial software tools. A rough overview of state-of-the-art on pillow plates can be found in. [ 2 ]
Research on pillow plates can be subdivided into three main categories: geometrical analysis, analysis of fluid flow and heat transfer in pillow plates and analysis of fluid flow and heat transfer in the gap between adjacent pillow plates.
Methods for the calculation of surface area, fluid hold-up volume, cross-sectional area and hydraulic diameter, needed in thermohydraulic calculations, have been proposed in. [ 3 ] The mentioned geometrical parameters were determined using Finite Element Analysis (FEM), which imitates the inflation process during manufacturing of pillow plates. Moreover, theoretical burst pressures of pillow plates, could be estimated with FEM.
The complex wavy geometry in pillow plate channels promotes fluid mixing, which leads to favorable heat transfer rates but is also unfavorable for pressure loss (formation of recirculation regions in the wake of welding spots). Information on fluid flow and heat transfer in pillow plates is available in, [ 4 ] while correlations for the calculation of Darcy-Friction-Factor and Nusselt number in pillow plates over a wide range of geometrical parameters variations and process conditions is found in. [ 5 ]
Similar to the inner channels of pillow plates, the channels formed between adjacent pillow plates (outer channels) are also wavy and promote fluid mixing, which is in turn favorable for heat transfer rates. However, pressure loss in the outer channels is significantly lower than in the inner ones because of the absence of welding spots, which act as obstacles for the flow (flow around welding spots). Information on fluid flow and heat transfer in the outer channels of pillow plate heat exchangers is available in. [ 6 ]
The reliable design of condensers, falling film evaporators and water chillers requires detailed knowledge of fluid dynamics and heat transfer of the falling liquid film over the surface of the pillow plates. [ 7 ] | https://en.wikipedia.org/wiki/Pillow-plate_heat_exchanger |
A pilot chute is a small auxiliary parachute used to deploy the main or reserve parachute. [ 1 ] The pilot chute is connected by a bridle to the deployment bag containing the parachute. Pilot chutes are a critical component of all modern skydiving and BASE jumping gear. Pilot chutes are also used as a component of spacecraft such as NASA's Orion . [ 2 ]
The spring-loaded pilot chute is used in conjunction with a ripcord . [ 3 ] When the user pulls the ripcord, the container opens, allowing the pilot chute compressed inside and loaded with a large spring inside it to jump out. Spring-loaded pilot chutes are mainly used to deploy reserve parachutes. They are often also used to deploy the main parachute on skydiving students' parachute equipment. They are also commonly used in drogue parachutes in cars or in planes such as the B52 Bomber.
The pull-out and throw-out pilot chutes are identical in construction; the difference is in their connection to the handle and the bridle, and in the way they are packed.
With the pull-out system, the pilot chute is packed inside the container. The activation handle is attached to a lanyard, which in turn is attached to the closing pin. The lanyard is also attached to base of the pilot chute, at the point of connection to the bridle. When the user pulls the handle, the closing pin is pulled, opening the container. Continuing the pull, the user pulls the pilot chute out of the container and into the airstream, at which point the pilot chute inflates and pulls the main parachute out of the container. [ 4 ]
The throw-out pilot chute is the most popular type in use today. The pilot chute is packed in a pouch at the bottom of the container. The handle is attached to the apex of the pilot chute. When the user grabs the handle and throws the pilot chute into the airstream, the bridle extends, pulling the closing pin and opening the container; as the pilot chute continues in the airstream it extracts the deployment bag containing the main parachute from the container. The pull-out pilot chute and the throw-out pilot chute were both invented by Bill Booth . [ 5 ]
Drogues used on tandem -systems are basically large throw-out pilot chutes, but the bridle is anchored on the container with a release system. When the user throws the drogue, the drogue inflates and the bridle extends. The deployed drogue slows down the free-fall speed of the tandem pair. When the user wants to open the parachute, they pull a ripcord, releasing the bridle and allowing the drogue to open the main container.
With the advent of smaller higher performance canopies, the drag induced by trailing a pilot chute behind a canopy has become a significant concern. To reduce this drag some pilot chute designs of the Pull-out and Throw-out variety are collapsible. Once deployment of the parachute has occurred a kill line running up the center of the pilot chute bridle becomes loaded. This kill line pulls down on the apex of the pilot chute collapsing it and greatly reducing its drag on the canopy. [ 6 ]
Some designs replace the kill line with a fixed length of shock cord , which stretches when the pilot chute is moving quickly, allowing it to inflate. When the pilot slows down (after opening a canopy, for example) the shock cord retracts, killing the pilot chute. While this avoids the possibility of pilot-in-tow malfunction due to an un-cocked pilot, it has the disadvantage of requiring significant airspeed to operate. This could cause a delayed deployment if used for a BASE or balloon jump, or any other jump with a low speed deployment. This type may also begin to re-inflate behind a highly loaded, fast moving canopy, negating the usefulness of a collapsible pilot chute.
Pilot chutes for BASE jumping gear are typically larger than skydiving pilot chutes, and often include air vents on the surface. Research on the development of early round parachutes showed that vents can increase stability and reduce oscillation of the parachute. BASE jumpers often use pilot chutes with either apex vents, or ring vents. [ 7 ] | https://en.wikipedia.org/wiki/Pilot_chute |
A pilot direction indicator or pilot's directional indicator ( PDI ) [ 1 ] is an aircraft instrument used by bombardiers to indicate heading changes to the pilot in order to direct them to the proper location to drop bombs . The PDI is used in aircraft where the pilot and bombardier are physically separated and cannot easily see each other. [ 2 ]
PDI's typically consist of a dial that is installed in the pilot's instrument set on the main console, with an arrow pointer than can be moved to indicate how far and in what direction to correct the heading. The bombardier typically has a switch to move the pointer to the right or left, and a repeater dial so he can see the setting.
The Norden bombsight was originally designed with the idea of automatically directing a PDI and thereby simplifying the bombardier's task.
This article about aircraft components is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pilot_direction_indicator |
A pilot plant is a pre-commercial production system that employs new production technology and/or produces small volumes of new technology-based products, mainly for the purpose of learning about the new technology. The knowledge obtained is then used for design of full-scale production systems and commercial products, as well as for identification of further research objectives and support of investment decisions. Other (non-technical) purposes include gaining public support for new technologies and questioning government regulations. [ 1 ] Pilot plant is a relative term in the sense that pilot plants are typically smaller than full-scale production plants, but are built in a range of sizes. Also, as pilot plants are intended for learning, they typically are more flexible, possibly at the expense of economy. Some pilot plants are built in laboratories using stock lab equipment, while others require substantial engineering efforts, cost millions of dollars, and are custom-assembled and fabricated from process equipment, instrumentation and piping. They can also be used to train personnel for a full-scale plant. Pilot plants tend to be smaller compared to demonstration plants.
A word similar to pilot plant is pilot line . [ 2 ] Essentially, pilot plants and pilot lines perform the same functions, but 'pilot plant' is used in the context of (bio)chemical and advanced materials production systems, whereas 'pilot line' is used for new technology in general. The term 'kilo lab' is also used for small pilot plants referring to the expected output quantities. [ 3 ]
Pilot plants are used to reduce the risk associated with construction of large process plants. They do so in several ways:
If a system is well defined and the engineering parameters are known, pilot plants are not used. For instance, a business that wants to expand production capacity by building a new plant that does the same thing as an existing plant may choose to not use a pilot plant.
Additionally, advances in process simulation on computers have increased the confidence of process designers and reduced the need for pilot plants. However, they are still used as even state-of-the-art simulation cannot accurately predict the behavior of complex systems.
As a system increases in size, system properties that depend on quantity of matter (with extensive properties ) may change. The surface area to liquid ratio in a chemical plant is a good example of such a property. On a small chemical scale, in a flask, say, there is a relatively large surface area to liquid ratio. However, if the reaction in question is scaled up to fit in a 500-gallon tank, the surface area to liquid ratio becomes much smaller. As a result of this difference in surface area to liquid ratio, the exact nature of the thermodynamics and the reaction kinetics of the process change in a non-linear fashion. This is why a reaction in a beaker can behave vastly differently from the same reaction in a large-scale production process.
Other factors that may change during the transformation to a production scale include:
After data has been collected from operation of a pilot plant, a larger production-scale facility may be built. Alternatively, a demonstration plant, which is typically bigger than a pilot plant, but smaller than a full-scale production plant, may be built to demonstrate the commercial feasibility of the process. Businesses sometimes continue to operate the pilot plant in order to test ideas for new products, new feedstocks, or different operating conditions. Alternatively, they may be operated as production facilities, augmenting production from the main plant.
The differences between bench scale, pilot scale and demonstration scale are strongly influenced by industry and application. Some industries use pilot plant and demonstration plant interchangeably. Some pilot plants are built as portable modules that can be easily transported as a contained unit.
For batch processes, in the pharmaceutical industry for example, bench scale is typically conducted on samples 1–20 kg or less, whereas pilot scale testing is performed with samples of 20–100 kg. Demonstration scale is essentially operating the equipment at full commercial feed rates over extended time periods to prove operational stability.
For continuous processes, in the petroleum industry for example, bench scale systems are typically microreactor or CSTR systems with less than 1000 mL of catalyst, studying reactions and/or separations on a once-through basis. Pilot plants will typically have reactors with catalyst volume between 1 and 100 litres, and will often incorporate product separation and gas/liquid recycle with the goal of closing the mass balance. Demonstration plants, also referred to as semi-works plants, will study the viability of the process on a pre-commercial scale, with typical catalyst volumes in the 100 - 1000 litre range. The design of a demonstration scale plant for a continuous process will closely resemble that of the anticipated future commercial plant, albeit at a much lower throughput, and its goal is to study catalyst performance and operating lifetime over an extended period, while generating significant quantities of product for market testing.
In the development of new processes, the design and operation of the pilot and demonstration plant will often run in parallel with the design of the future commercial plant, and the results from pilot testing programs are key to optimizing the commercial plant flowsheet. It is common in cases where process technology has been successfully implemented that the savings at the commercial scale resulting from pilot testing will significantly outweigh the cost of the pilot plant itself.
Custom pilot plants are commonly designed either for research or commercial purposes. They can range in size from a small system with no automation and low flow, to a highly automated system producing relatively large amounts of products in a day. No matter the size, the steps to designing and fabricating a working pilot plant are the same. They are: | https://en.wikipedia.org/wiki/Pilot_plant |
A pilus ( Latin for 'hair'; pl. : pili ) is a hair-like cell-surface appendage found on many bacteria and archaea . [ 1 ] The terms pilus and fimbria (Latin for 'fringe'; plural: fimbriae ) can be used interchangeably, although some researchers reserve the term pilus for the appendage required for bacterial conjugation . All conjugative pili are primarily composed of pilin – fibrous proteins , which are oligomeric .
Dozens of these structures can exist on the bacterial and archaeal surface. Some bacteria, viruses or bacteriophages attach to receptors on pili at the start of their reproductive cycle.
Pili are antigenic . They are also fragile and constantly replaced, sometimes with pili of different composition, resulting in altered antigenicity. Specific host responses to old pili structures are not effective on the new structure. Recombination between genes of some (but not all) pili code for variable (V) and constant (C) regions of the pili (similar to immunoglobulin diversity). As the primary antigenic determinants, virulence factors and impunity factors on the cell surface of a number of species of gram-negative and some gram-positive bacteria , including Enterobacteriaceae , Pseudomonadaceae , and Neisseriaceae , there has been much interest in the study of pili as an organelle of adhesion and as a vaccine component. The first detailed study of pili was done by Brinton and co-workers who demonstrated the existence of two distinct phases within one bacterial strain: pileated (p+) and non-pileated) [ 2 ]
A few names are given to different types of pili by their function. The classification does not always overlap with the structural or evolutionary-based types, as convergent evolution occurs. [ 3 ]
Conjugative pili allow for the transfer of DNA between bacteria, in the process of bacterial conjugation . They are sometimes called "sex pili", in analogy to sexual reproduction , because they allow for the exchange of genes via the formation of "mating pairs". Perhaps the most well-studied is the F-pilus of Escherichia coli , encoded by the F sex factor .
A sex pilus is typically 6 to 7 nm in diameter. During conjugation, a pilus emerging from the donor bacterium ensnares the recipient bacterium, draws it in close, and eventually triggers the formation of a mating bridge , which establishes direct contact and the formation of a controlled pore that allows transfer of DNA from the donor to the recipient. Typically, the DNA transferred consists of the genes required to make and transfer pili (often encoded on a plasmid ), and so is a kind of selfish DNA ; however, other pieces of DNA are often co-transferred and this can result in dissemination of genetic traits throughout a bacterial population, such as antibiotic resistance . The connection established by the F-pilus is extremely mechanically and thermochemically resistant thanks to the robust properties of the F-pilus, which ensures successful gene transfer in a variety of environments. [ 5 ] Not all bacteria can make conjugative pili, but conjugation can occur between bacteria of different species. [ 6 ] [ 7 ]
Hyperthermophilic archaea encode pili structurally similar to the bacterial conjugative pili. [ 8 ] However, unlike in bacteria, where conjugation apparatus typically mediates the transfer of mobile genetic elements, such as plasmids or transposons, the conjugative machinery of hyperthermophilic archaea, called Ced (Crenarchaeal system for exchange of DNA) [ 9 ] and Ted (Thermoproteales system for exchange of DNA), [ 8 ] appears to be responsible for the transfer of cellular DNA between members of the same species. It has been suggested that in these archaea the conjugation machinery has been fully domesticated for promoting DNA repair through homologous recombination rather than spread of mobile genetic elements. [ 8 ]
Fimbria ( Latin for 'fringe', pl. : fimbriae ) is a term used for a short pilus, an appendage that is used to attach the bacterium to a surface, sometimes also called an "attachment pilus" [ 10 ] or adhesive pilus . The term "fimbria" can refer to many different (structural) types of pilus. Indeed, many different types of pili have been used for adhesion, a case of convergent evolution . [ 3 ] The Gene Ontology system does not treat fimbriae as a distinct type of appendage, using the generic pilus (GO:0009289) type instead.
This appendage ranges from 3–10 nanometers in diameter and can be as much as several micrometers long. Fimbriae are used by bacteria to adhere to one another and to adhere to animal cells and some inanimate objects. A bacterium can have as many as 1,000 fimbriae. Fimbriae are only visible with the use of an electron microscope . They may be straight or flexible.
Fimbriae possess adhesins which attach them to some sort of substratum so that the bacteria can withstand shear forces and obtain nutrients. For example, E. coli uses them to attach to mannose receptors .
Some aerobic bacteria form a very thin layer at the surface of a broth culture . This layer, called a pellicle , consists of many aerobic bacteria that adhere to the surface by their fimbriae. Thus, fimbriae allow the aerobic bacteria to remain both on the broth, from which they take nutrients, and near the air.
Fimbriae are required for the formation of biofilm , as they attach bacteria to host surfaces for colonization during infection. Fimbriae are either located at the poles of a cell or are evenly spread over its entire surface.
This term was also used in a lax sense to refer to all pili, by those who use "pilus" to specifically refer to sex pili. [ 11 ]
The Tra (transfer) family includes all known sex pili (as of 2010). They are related to the type IV secretion system (T4SS). [ 3 ] They can be classified into the F-like type (after the F-pilus) and the P-like type. Like their secretion counterparts, the pilus injects material, DNA in this case, into another cell. [ 12 ]
Some pili, called type IV pili (T4P), generate motile forces. [ 14 ] The external ends of the pili adhere to a solid substrate, either the surface to which the bacterium is attached or to other bacteria. Then, when the pili contract, they pull the bacterium forward like a grappling hook. Movement produced by type IV pili is typically jerky, so it is called twitching motility , as opposed to other forms of bacterial motility such as that produced by flagella . However, some bacteria, for example Myxococcus xanthus , exhibit gliding motility . Bacterial type IV pili are similar in structure to the component proteins of archaella (archaeal flagella), and both are related to the Type II secretion system (T2SS); [ 15 ] they are unified by the group of Type IV filament systems. Besides archaella, many archaea produce adhesive type 4 pili, which enable archaeal cells to adhere to different substrates. The N-terminal alpha-helical portions of the archaeal type 4 pilins and archaellins are homologous to the corresponding regions of bacterial T4P; however, the C-terminal beta-strand-rich domains appear to be unrelated in bacterial and archaeal pilins. [ 16 ]
Genetic transformation is the process by which a recipient bacterial cell takes up DNA from a neighboring cell and integrates this DNA into its genome by homologous recombination . In Neisseria meningitidis (also called meningococcus), DNA transformation requires the presence of short DNA uptake sequences (DUSs) which are 9-10 monomers residing in coding regions of the donor DNA. Specific recognition of DUSs is mediated by a type IV pilin . [ 17 ] Menningococcal type IV pili bind DNA through the minor pilin ComP via an electropositive stripe that is predicted to be exposed on the filament's surface. ComP displays an exquisite binding preference for selective DUSs. The distribution of DUSs within the N. meningitides genome favors certain genes, suggesting that there is a bias for genes involved in genomic maintenance and repair. [ 18 ] [ 19 ]
This family was originally identified as "type IV fimbriae" by their appearance under the microscope. This classification survived as it happens to correspond to a clade. [ 20 ] It has been shown that some archaeal type IV pilins can exist in 4 different conformations, yielding two pili with dramatically different structures. [ 21 ] Remarkably, the two pili were produced by the same secretion machinery. However, which of the two pili is formed appears to depend on the growth conditions, suggesting that the two pili are functionally distinct. [ 21 ]
Another type are called type 1 fimbriae. [ 22 ] They contain FimH adhesins at the "tips". The chaperone-usher pathway is responsible for moving many types of fimbriae out of the cell, including type 1 fimbriae [ 23 ] and the P fimbriae . [ 24 ]
"Gram-negative bacteria assemble functional amyloid surface fibers called curli ." [ 26 ] Curli are a type of fimbriae. [ 22 ] Curli are composed of proteins called curlins. [ 26 ] Some of the genes involved are CsgA , CsgB , CsgC , CsgD , CsgE , CsgF , and CsgG . [ 26 ]
Pili are responsible for virulence in the pathogenic strains of many bacteria, including E. coli , Vibrio cholerae , and many strains of Streptococcus . [ 27 ] [ 28 ] This is because the presence of pili greatly enhances bacteria's ability to bind to body tissues, which then increases replication rates and ability to interact with the host organism. [ 27 ] If a species of bacteria has multiple strains but only some are pathogenic, it is likely that the pathogenic strains will have pili while the nonpathogenic strains do not. [ 29 ] [ 30 ]
The development of attachment pili may then result in the development of further virulence traits. Fimbriae are one of the primary mechanisms of virulence for E. coli , Bordetella pertussis , Staphylococcus and Streptococcus bacteria. Their presence greatly enhances the bacteria's ability to attach to the host and cause disease. [ 31 ] Nonpathogenic strains of V. cholerae first evolved pili, allowing them to bind to human tissues and form microcolonies . [ 27 ] [ 30 ] These pili then served as binding sites for the lysogenic bacteriophage that carries the disease-causing toxin . [ 27 ] [ 30 ] The gene for this toxin, once incorporated into the bacterium's genome, is expressed when the gene coding for the pilus is expressed (hence the name "toxin mediated pilus"). [ 27 ] | https://en.wikipedia.org/wiki/Pilus |
Pimascovirales is an order of viruses . [ 1 ] The term is a portmanteau of a portmanteau of pitho -, irido-, marseille-, and ascoviruses. [ 2 ]
Pimascovirales contains six families, three of which are assigned to a suborder. This taxonomy is shown hereafter: [ 1 ]
This virus -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pimascovirales |
A pin insulator is a device that isolates a wire from a physical support such as a pin (a wooden or metal dowel of about 3 cm diameter with screw threads) on a telegraph or utility pole . It is a formed, single layer shape that is made out of a non-conducting material, usually porcelain or glass . It is thought to be the earliest developed overhead insulator and is still popularly used in power networks up to 33 KV. Single or multiple pin insulators can be used on one physical support, however, the number of insulators used depends upon the application's voltage. [ 1 ]
Pin insulators are one of three types of overhead insulators, the others being strain insulators and suspension insulators. Unlike the others, pin insulators are directly connected to the physical support compared to being suspended from the wire. Pin insulators are shaped to allow the secure attachment of the conducting wire and avoid it coming adrift. The wire is usually attached to the insulator by being wrapped around it or in other circumstances, fixed into grooves on the insulator itself. [ 2 ]
When an insulator is wet, its outer surface becomes conductive making the insulator less effective. An insulator has an umbrella-like design so that it can protect the lower part of the insulator from rain. To keep the inner side of the insulator dry, ridges around the insulator, "rain sheds", are made. These increase the creepage distance from the energized wire to the mounting pin. [ 3 ]
Pin insulators have become collectible items . All glass pin insulators are assigned a Consolidated Design (CD) number, a system first implemented by hobbyist N.R. Woodward in 1954, and widely introduced starting in 1965 by collector Helmer Turner. CD numbers first appeared in print in Woodward’s “Glass insulators in America, 1967 report”. Each CD number corresponds to a specific glass style, shape, or manufacturer. CD numbers are only hobby-specific for collectors, and are not used or recognised by insulator manufacturers. [ 4 ]
Insulators, at the time of manufacturing, were simply viewed as an engineering product and were not meant to be an entertainment product for spectators. This meant that the quality of the insulators was not a primary concern of the manufacturers that made them. [ 5 ] The finished product was usually discoloured from impurities and foreign objects diffused within the molten glass and metal molds. These impurities give the insulator a unique character and high value as collectors would rather obtain an imperfect product rather than a perfect, common product. Impurities in the glass can create amber swirls, milk swirls, graphite inclusions, and two or three-tone insulators. Foreign objects contained within the glass are known to be nails, pennies, and screws. [ 6 ]
Although glass insulators are the most popular for the majority of collectors, many people collect porcelain insulators as well. These also come in a variety of shapes, sizes, and colors. They are classified in the U and M systems, primarily developed by Jack Tod and Elton Gish. [ 7 ]
One of the major U.S. manufacturers that produced glass insulators during the 19th century and early 20th century in the USA was Brookfield Glass Company . It can be assumed that Brookfield may have had poor quality control as their insulators seem to be found with the most imperfections, however, this could be disputed.
Another major U.S. manufacturer that produced glass insulators was the Hemingray Glass Company . They were known for producing the most variety of colors. Some examples of colors that the company produced are yellow, golden yellow, butterscotch, glowing orange, amber, whiskey amber, "root beer" amber, orange-amber, red-amber, oxblood, green, lime green, sage green, depression green, emerald green, olive green, yellow-olive green, aqua, cornflower blue, electric blue, cobalt blue, sapphire blue, glowing peacock blue, and many others. Different colors were produced to allow two or more different utility companies to quickly identify which wires were theirs by the color of insulator if multiple wires were strung over the same utility pole. For example, one company may have a string of amber insulators, while another, on the same poles, might have their insulators in cobalt blue.
There are many manufacturers in the United States , Canada , and other countries that can be found embossed on all styles of insulators. A non-comprehensive list of these manufacturers is below: | https://en.wikipedia.org/wiki/Pin_insulator |
The Pin matrix is a compact and visual to way to semi-permanently route signals or program devices, such as in early digital electronics [ 1 ] [ 2 ] or lighting control boards. [ 3 ] [ 4 ]
The number of patches that can be made is limited [ 5 ] and the proximity of signal wires in the matrix can cause crosstalk . [ 6 ]
Also know for being used to patch (program) some synthesizers . Generally inputs are on one axis and outputs on the other and a pin inserted where the two axes meet establishes a connection. [ 5 ]
This article incorporates text available under the CC BY-SA 4.0 license.
This technology-related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pin_matrix |
Pinatuzumab vedotin ( INN ; [ 1 ] development codes DCDT2980S and FCU2703 ) is a monoclonal antibody designed for the treatment of B-cell malignancies. [ 2 ]
This drug was developed by Genentech / Roche . [ citation needed ]
This monoclonal antibody –related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pinatuzumab_vedotin |
Pinch analysis is a methodology for minimising energy consumption of chemical processes by calculating thermodynamically feasible energy targets (or minimum energy consumption) and achieving them by optimising heat recovery systems, energy supply methods and process operating conditions. It is also known as process integration , heat integration , energy integration or pinch technology .
The process data is represented as a set of energy flows, or streams, as a function of heat load (product of specific enthalpy and mass flow rate ; SI unit W ) against temperature (SI unit K ). These data are combined for all the streams in the plant to give composite curves , one for all hot streams (releasing heat) and one for all cold streams (requiring heat). The point of closest approach between the hot and cold composite curves is the pinch point (or just pinch ) with a hot stream pinch temperature and a cold stream pinch temperature. This is where the design is most constrained. Hence, by finding this point and starting the design there, the energy targets can be achieved using heat exchangers to recover heat between hot and cold streams in two separate systems, one for temperatures above pinch temperatures and one for temperatures below pinch temperatures. In practice, during the pinch analysis of an existing design, often cross-pinch exchanges of heat are found between a hot stream with its temperature above the pinch and a cold stream below the pinch. Removal of those exchangers by alternative matching makes the process reach its energy target .
In 1971, Ed Hohmann stated in his PhD thesis that
one can compute the least amount of hot and cold utilities required for a process without knowing the heat exchanger network that could accomplish it. One also can estimate the heat exchange area required
In late 1977, Ph.D. student Bodo Linnhoff under the supervision of Dr John Flower at the University of Leeds [ 1 ] showed the existence in many processes of a heat integration bottleneck, ‘the pinch’, which laid the basis for the technique, known today as pinch-analysis. At that time he had joined Imperial Chemical Industries (ICI) where he led practical applications and further method development.
Bodo Linnhoff developed the 'Problem Table', an algorithm for calculating the energy targets and worked out the basis for a calculation of the surface area required, known as ‘the spaghetti network’. These algorithms enabled practical application of the technique.
In 1982 he joined University of Manchester Institute of Technology ( UMIST , present day University of Manchester ) to continue the work. In 1983 he set up a consultation firm known as Linnhoff March International later acquired by KBC Energy Services .
Many refinements have been developed since and used in a wide range of industries, including extension to heat and power systems and
non-process situations. The most detailed explanation of the techniques is by Linnhoff et al. (1982), [ 2 ] Shenoy (1995), [ 3 ] Kemp (2006) [ 4 ] and Kemp and Lim (2020), [ 5 ] while Smith (2005) [ 6 ] includes several chapters on them. Both detailed and simplified (spreadsheet) programs are now available to calculate the energy targets. See Pinch Analysis Software below.
Pinch analysis has been extended beyond energy applications. It now includes:
Classical pinch-analysis primarily calculates the energy costs for the heating and cooling utility. At the pinch point, where the hot and cold streams are the most constrained, large heat exchangers are required to transfer heat between the hot and cold streams. Large heat exchangers entail high investment costs. In order to reduce capital cost, in practice a minimum temperature difference (Δ T) at the pinch point is demanded, e.g., 10 °F. It is possible to estimate the heat exchanger area and capital cost, and hence the optimal Δ T minimum value. However, the cost curve is quite flat and the optimum may be affected by "topology traps". The pinch method is not always appropriate for simple networks or where severe operating constraints exist. Kemp (2006) [ 4 ] and Kemp and Lim (2019) discuss these aspects in detail.
The problem of integrating heat between hot and cold streams, and finding the optimal network, in particular in terms of costs, may today be solved with numerical algorithms . The network can be formulated as a so-called mixed integer non-linear programming (MINLP) problem and solved with an appropriate numerical solver . Nevertheless, large-scale MINLP problems can still be hard to solve for today's numerical algorithms. Alternatively, some attempts were made to formulate the MINLP problems to mixed integer linear problems, where then possible networks are screened and optimized. For simple networks of a few streams and heat exchangers, hand design methods with simple targeting software are often adequate, and aid the engineer in understanding the process. [ 13 ] | https://en.wikipedia.org/wiki/Pinch_analysis |
A pinch point or pinch point hazard is a common class of mechanical hazard where injury or damage may be done by one or more objects moving towards each other, crushing or shearing whatever comes between them. [ 1 ] A nip point is a type of pinch point involving rotating objects, such as gears and pulleys. [ 2 ] Injuries can range from minor such as blisters to severe like amputations and fatalities. [ 3 ] Examples of pinch point hazards include gaps in closing doors and objects swinging or being lowered near fixed objects. [ 4 ]
Pre-work hazard inspections can be performed to identify pinch point hazards. These hazards can be managed with control methods, listed below according to the hazard control hierarchy . [ 1 ]
Engineering controls physically prevent objects from entering the pinch point.
Administrative controls inform worker behavior to avoid pinch points.
Personal protective equipment protects individuals exposed to the hazard by preventing objects from being pinched. [ 1 ]
. | https://en.wikipedia.org/wiki/Pinch_point_hazard |
In mathematics , the Pincherle polynomials P n ( x ) are polynomials introduced by S. Pincherle ( 1891 ) given by the generating function
Humbert polynomials are a generalization of Pincherle polynomials
This polynomial -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pincherle_polynomials |
Pinealon is a synthetic tripeptide of sequence (Glu-Asp-Arg) and purported geroprotector documented in the Russian scientific literature. [ 1 ] [ 2 ] [ 3 ] [ 4 ]
Pinealon has been shown to protect rat offspring from prenatal hyperhomocysteinemia and correspondingly improve post natal cognitive function. [ 5 ]
Pinealon likewise maintains learning retention rats with experimentally-induced diabetes. [ 6 ] As well as old humans and young wrestlers. [ 7 ]
Pinealon has been tested in large scale Human trials such as the Gasprom study, where it showed profound Geroprotective effects. This included longer telomeres and improvements in various health markers. [ 7 ] [ dubious – discuss ]
Pinealon is a tripeptide composed of L -glutamic acid , L -aspartic acid , and L -arginine and is notated as Glu-Asp-Arg or EDR. [ 8 ]
This article about medicinal chemistry is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pinealon |
Ping-pong recording (also called ping-ponging , bouncing tracks , or reduction mixing ) is a method of sound recording . It involves combining multiple track stems into one, allowing more room for overdubbing when using tape recorders with a limited set of tracks. It is also used to simplify mixdowns .
The two most common methods consist of
In both cases, a new instrument , voice, or other material may be added with each bounce, depending on the setup's mixing capabilities.
In analog recording , the audio quality normally decreases with each generation, while in digital recording , the quality is usually preserved. In either case, the most leeway comes with having the best possible source material.
The method was employed by Beach Boys co-founder Brian Wilson during the 1960s. For the recording of Pet Sounds (1966), Wilson created the instrumentals of songs using a 4-track recorder. He then bounced the material onto one track of an 8-track recorder, using the remaining tracks for vocal overdubs. This meant that the album could not be suitably mixed in stereo, because the instrumental parts were locked in monaural . In 1997, advances in recording technology allowed engineer Mark Linett to resync the original first-generation instrumental stems with the second-generation overdubbed vocals for the compilation The Pet Sounds Sessions and create a true stereo mix of the album. [ 1 ]
Ping pong is also a term of derision, in particular applied to early commercial stereo recordings of the late 1950s to mid-1960s which do not have a convincing stereo image or sound-stage. Such recordings were often made in two-track form for mixing in mono, but released as authentic stereo recordings.
This sound technology article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Ping-pong_recording |
PingER , an acronym for Ping End-to-end Reporting, measures round-trip travel time of a packet of data between two nodes on the Internet. The PingER' Project uses a simple tool—the ping command —to get valuable insights into performance of the Internet backbone . [ 1 ]
High energy particle physicists began the project in 1995, because they needed to access large amounts of data at laboratories sometimes as far away as across an ocean. They needed to know how the Internet was performing, identify problems, and apply solutions. [ 2 ] At U.S.Department of Energy's SLAC National Accelerator Laboratory , PingER let researcher Les Cottrell "keep tabs on how parts of the network were performing and root out any problems." [ 3 ] PingER is one of several collaborative projects having measurement infrastructures for monitoring Internet Traffic. [ 4 ] [ 5 ] [ 6 ] [ 7 ]
Using the ping command, monitoring nodes initiate transmissions to remote nodes, then measure and record the response times, or the lack of
responses. [ 2 ] [ 8 ] Each combination of monitoring node-remote node is called a pair. PingER is easy to implement, because little special software must be installed to make measurements. Almost any networked computer will respond to a ping, and require nothing added. [ 9 ] Monitoring nodes require only a script to issue ping commands and record results. In September 1999 there were 1977 pairs, consisting of 511 remote nodes in 54 countries. [ 1 ] [ 10 ]
PingER uses the data to determine latency (round-trip_time), jitter (variability of round-trip_time), and loss (percentage of packets that never return). The results of the PingER Project, including source code, are made available to the public at no cost. [ 1 ] [ 11 ] This collection of data shows long term world-wide Internet performance trends, covering over 750 sites in over 165 countries. [ 12 ] Researchers at the National University of Sciences and Technology, Pakistan , have been dealing with increasingly large amounts of PingER data by using a relational database. [ 13 ] From a vantage point between Europe and Africa, researchers at the International Centre for Theoretical Physics (ICTP) in Italy used PingER to reveal the slow progress of improving Africa's connections to the rest of the world. [ 14 ]
Analysis of some of the PingER data reveal that: [ 15 ] | https://en.wikipedia.org/wiki/PingER_Project |
A ping test is a physical test to determine the natural frequency of an object or assembly. [ 1 ] The test consists of instrumenting the object or assembly with measuring devices and then tapping it with another metallic object (usually a hammer.) The undamped system will then vibrate at its natural frequency. The ping test is used on assemblies and objects where vibration can be an issue.
This engineering-related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Ping_test_(engineering) |
The pinhole camera model describes the mathematical relationship between the coordinates of a point in three-dimensional space and its projection onto the image plane of an ideal pinhole camera , where the camera aperture is described as a point and no lenses are used to focus light. The model does not include, for example, geometric distortions or blurring of unfocused objects caused by lenses and finite sized apertures. [ 1 ] It also does not take into account that most practical cameras have only discrete image coordinates. This means that the pinhole camera model can only be used as a first order approximation of the mapping from a 3D scene to a 2D image . Its validity depends on the quality of the camera and, in general, decreases from the center of the image to the edges as lens distortion effects increase.
Some of the effects that the pinhole camera model does not take into account can be compensated, for example by applying suitable coordinate transformations on the image coordinates; other effects are sufficiently small to be neglected if a high quality camera is used. This means that the pinhole camera model often can be used as a reasonable description of how a camera depicts a 3D scene, for example in computer vision and computer graphics .
The geometry related to the mapping of a pinhole camera is illustrated in the figure. The figure contains the following basic objects:
The pinhole aperture of the camera, through which all projection lines must pass, is assumed to be infinitely small, a point. In the literature this point in 3D space is referred to as the optical (or lens or camera) center . [ 3 ]
Next we want to understand how the coordinates ( y 1 , y 2 ) {\displaystyle (y_{1},y_{2})} of point Q depend on the coordinates ( x 1 , x 2 , x 3 ) {\displaystyle (x_{1},x_{2},x_{3})} of point P . This can be done with the help of the following figure which shows the same scene as the previous figure but now from above, looking down in the negative direction of the X2 axis.
In this figure we see two similar triangles , both having parts of the projection line (green) as their hypotenuses . The catheti of the left triangle are − y 1 {\displaystyle -y_{1}} and f and the catheti of the right triangle are x 1 {\displaystyle x_{1}} and x 3 {\displaystyle x_{3}} . Since the two triangles are similar it follows that
A similar investigation, looking in the negative direction of the X1 axis gives
This can be summarized as
which is an expression that describes the relation between the 3D coordinates ( x 1 , x 2 , x 3 ) {\displaystyle (x_{1},x_{2},x_{3})} of point P and its image coordinates ( y 1 , y 2 ) {\displaystyle (y_{1},y_{2})} given by point Q in the image plane.
The mapping from 3D to 2D coordinates described by a pinhole camera is a perspective projection followed by a 180° rotation in the image plane. This corresponds to how a real pinhole camera operates; the resulting image is rotated 180° and the relative size of projected objects depends on their distance to the focal point and the overall size of the image depends on the distance f between the image plane and the focal point. In order to produce an unrotated image, which is what we expect from a camera, there are two possibilities:
In both cases, the resulting mapping from 3D coordinates to 2D image coordinates is given by the expression above, but without the negation, thus
The mapping from 3D coordinates of points in space to 2D image coordinates can also be represented in homogeneous coordinates . Let x {\displaystyle \mathbf {x} } be a representation of a 3D point in homogeneous coordinates (a 4-dimensional vector), and let y {\displaystyle \mathbf {y} } be a representation of the image of this point in the pinhole camera (a 3-dimensional vector). Then the following relation holds
where C {\displaystyle \mathbf {C} } is the 3 × 4 {\displaystyle 3\times 4} camera matrix and the ∼ {\displaystyle \,\sim } means equality between elements of projective spaces . This implies that the left and right hand sides are equal up to a non-zero scalar multiplication. A consequence of this relation is that also C {\displaystyle \mathbf {C} } can be seen as an element of a projective space ; two camera matrices are equivalent if they are equal up to a scalar multiplication. This description of the pinhole camera mapping, as a linear transformation C {\displaystyle \mathbf {C} } instead of as a fraction of two linear expressions, makes it possible to simplify many derivations of relations between 3D and 2D coordinates. [ citation needed ] | https://en.wikipedia.org/wiki/Pinhole_camera_model |
Pink Visual is an independent reality and gonzo pornography film production company, based in Van Nuys, California , United States. It began as an Internet pornography provider before eventually moving into DVD production. Pink Visual also licenses adult content to cable , satellite , pay-per-view , hotel chain channels, and other Internet content licensees. Currently marketing their content with the tagline of "Raw. Raunchy. Real." , Pink Visual content is largely reality-based, taking inspiration from reality television . Pink Visual's porn productions typically utilize amateur performers and are shot in a 'Pro-am' style, utilizing digital video, including the high definition format.
Founded in June 2004, Pink Visual evolved out of the formerly established TopBucks webmaster affiliate program, which gave Pink Visual the content and marketing resources to launch into the DVD market. [ citation needed ]
On February 4, 2009, Pink Visual offered a $10 discount on selected sites in "compensation for (the) Super Bowl porn mishap" in which Tucson, AZ area Comcast customers had their service interrupted for 30 seconds by an uncensored Pink Visual video. [ 1 ] [ 2 ]
Apparently closed its online site Aug. 15, 2023. [ 3 ]
In 2008, Pink Visual launched iPinkVisual.com and iPinkVisualPass.com, the first major U.S.-based mobile porn websites designed especially for iPhones . [ 4 ]
In June 2009, Pink Visual tweaked the mobile compatibility of their sites to include functionality with other WebKit based browsers, including the Palm Pre and mobile devices running on Google Android . Pink Visual mobile porn sports a limited functionality with certain BlackBerry devices. Pink Visual has released an app on the MiKandi app store for Android. [ 5 ]
In April 2010, Pink Visual launched PinkVisualPad.com, the first major porn website designed especially for the newly released iPad . [ 6 ] This release was followed soon after by the release of MaleSpectrumPad.com, the first gay website designed for iPad compatibility. [ 7 ]
In December 2008, Pink Visual premiered Male Spectrum, a new line of gay pornography home video titles focusing on premium, high-quality gay reality porn content. In addition to the DVD line, Male Spectrum has also launched two gay mobile sites compatible with the iPhone and other multimedia capable mobile devices, iMaleSpectrum.com and iMaleSpectrumPass.com. Recently, Male Spectrum made an initial donation of $2500 to the Human Rights Campaign to assist in the HRC's fight against discrimination. [ 8 ]
Pink Visual launched PVLocker.com in March 2011 as a way to fulfill the evolving consumer demands for adult content that was affordable and accessible from multiple devices from mobile phones, to tablets, to PCs. PVLocker allows customers to purchase just the scenes that they want and access them forever from within their locker. Additionally, PVLocker has an upload feature where customers can store already purchased adult content from other sources and access the content from multiple devices. PVLocker.com allows consumers to hide or store their porn off their local computers and in the cloud.
PVLocker.com also aggregates adult content from various XXX studios including: Private Media, Holly Randall, Acid Rain, Grind House, Wasteland, Juicy Pink Box, and Sssh.
In September 2011, Pink Visual announced that in preparation for the 2012 apocalypse predicted by the Mayan calendar , they are building a massive underground bunker . [ 9 ] The bunker will contain all of the obvious emergency supplies and facilities as well as a few amenities. The bunker will have multiple fully stocked bars, an enormous performing stage with a rotating hydraulic platform and a sophisticated content production studio. [ 10 ] The apocalypse bunker was scheduled to be ready by September 2012 and preliminary blueprints have been released. [ 11 ]
In March 2009, Pink Visual and Male Spectrum have made news by donating a portion of their proceeds to Trees for the Future as well as for releasing an environmentally friendly DVD line, Plant Your Wood. The company is also working to turn their web sites carbon neutral . [ 12 ]
On January 18, 2010, Conan O'Brien revealed that he was offered to star in a Pink Visual porno entitled "Conan the Boobarian" among other job offers following his high-profile exit from The Tonight Show . [ 13 ]
Pink Visual’s Anti-Piracy strategy is directed by its General Counsel, Jessica Pena. Pena joined the company in 2008 and immediately recognized the widespread effect of online piracy both for Pink Visual and the adult entertainment industry as a whole. Pena began using litigation strategies to combat online copyright infringement focusing not only on the recovery of damages, but the use of technology to prevent future infringement. Pena’s approach has evolved to incorporate site operator litigation, legal pressure, end-user education, content removal services and the development of reasonable alternatives to piracy. “In some ways, the mainstream entertainment space is way ahead of the adult sector in terms of how it fights piracy.” Pena states, “Having said that, there are some interesting anti-piracy approaches that adult rights-holders are taking, so my goal is to encourage the minds from both sectors to come together and share ideas that will create even more effective strategies.” [ 14 ]
In February 2010, Pink Visual’s holding company Ventura Content, Ltd. filed suit in the U.S. District Court for New York against Mansef, Inc. the owners of Brazzers, alleging that four company-owned tube sites infringed on 45 copyrighted movies. [ 15 ] The suit was settled in October 2010, with terms that remain confidential, other than an agreement between the parties that the site operators would implement digital fingerprint filtering on their sites. [ 16 ]
In December 2010, Pink Visual filed suit against the operators of SlutLoad.com, alleging infringement on 53 Pink Visual works. [ 17 ] The suit was settled in March, 2011, and once again included an agreement that the defendant would implement digital fingerprint filtering. [ 18 ]
In July 2011, Pink Visual filed suit against Motherless.com, alleging copyright infringement in connection with 19 Pink Visual works, as well as unfair competition for its failure to abide by the adult industries’ age verification and record keeping requirements. [ 19 ] Motherless won the case, with the judge ruling they were entitled to the DMCA 's safe-harbor provisions. [ 20 ] Pink Visual's appeal was thrown out in 2018. [ 21 ]
In September 2011, Pink Visual filed suit against Two Point Oh Ltd., which operates multiple popular adult sites, alleging infringement on 92 Pink Visual works. [ 22 ] The suit was settled in December, 2011 under confidential terms. However, the parties entered into a consent judgment whereby Two Point Oh recognizes that digital fingerprint filtering is a reasonable technical measure to prevent online copyright infringement in the adult arena.
In addition to the litigation the company has undertaken to combat copyright infringement, Pink Visual has also organized and hosted two Content Protection Retreats, (CPR) in order to provide information to other adult studios on copyright law and engage in discussions regarding industry strategies, as a whole, to combat piracy. The first CPR took place in October 2010, in Tucson, Arizona. [ 23 ] A second CPR was held in February, 2011 in Hollywood California. [ 24 ] Dozens of adult entertainment studios participated in the events, hearing presentations from intellectual property attorneys, companies that provide content take-down services and other experts in copyright enforcement and anti-piracy strategy.
Pink Visual cites a clear anti-piracy policy to their consumers and looks to educate end-users about the dangers and risks of piracy. Pink Visual content is prohibited from being distributed on torrents and Cyberlocker sites. Pink Visual recommends that consumers purchase legally and provides numerous methods for consumers to access their content legally. Illegal downloads of PinkVisual content are prohibited and considered copyright infringement.
In 2012, Pink Visual established an anti-piracy service of its own that performs online copyright infringement location, trademark monitoring, copyright registration and DMCA takedown notice services for rights-holders. | https://en.wikipedia.org/wiki/Pink_Visual |
Pink flowers are used as a symbol of love and awareness. For decades, pink flowers have been used to decorate weddings as a symbol of love. [ 1 ] They can also be used as a display of love at funerals, as demonstrated at the funeral for Anna Nicole Smith . [ 2 ] [ 3 ]
More recently, pink flowers have come to symbolize breast cancer awareness . [ 4 ]
They may also be used as an expression of thanks, [ 5 ] or just enjoyed for their aesthetic beauty. [ 6 ] [ 7 ]
Species of pink flowers include: | https://en.wikipedia.org/wiki/Pink_flowers |
Trinitrotoluene ( / ˌ t r aɪ ˌ n aɪ t r oʊ ˈ t ɒ lj u iː n / ), [ 5 ] [ 6 ] more commonly known as TNT (and more specifically 2,4,6-trinitrotoluene , and by its preferred IUPAC name 2-methyl-1,3,5-trinitrobenzene ), [ 1 ] is a chemical compound with the formula C 6 H 2 (NO 2 ) 3 CH 3 . TNT is occasionally used as a reagent in chemical synthesis , but it is best known as an explosive material with convenient handling properties. The explosive yield of TNT is considered to be the standard comparative convention of bombs and asteroid impacts. In chemistry , TNT is used to generate charge transfer salts .
TNT was first synthesized in 1861 by German chemist Julius Wilbrand [ 7 ] and was originally used as a yellow dye. Its potential as an explosive was not recognized for three decades, mainly because it was so much less sensitive than other explosives known at the time. Its explosive properties were discovered in 1891 by another German chemist, Carl Häussermann. [ 8 ] TNT can be safely poured when liquid into shell cases, and is so insensitive that in 1910 it was exempted from the UK's Explosives Act 1875 and was not considered an explosive for the purposes of manufacture and storage. [ 9 ]
The German armed forces adopted it as a filling for artillery shells in 1902. TNT-filled armour-piercing shells would explode after they had penetrated the armour of British capital ships , whereas the British Lyddite -filled shells tended to explode upon striking armour, thus expending much of their energy outside the ship. [ 9 ] The British started replacing Lyddite with TNT in 1907. [ 10 ]
The United States Navy continued filling armour-piercing shells with explosive D after some other nations had switched to TNT, but began filling naval mines , bombs , depth charges , and torpedo warheads with burster charges of crude grade B TNT with the color of brown sugar and requiring an explosive booster charge of granular crystallized grade A TNT for detonation. High-explosive shells were filled with grade A TNT, which became preferred for other uses as industrial chemical capacity became available for removing xylene and similar hydrocarbons from the toluene feedstock and other nitrotoluene isomer byproducts from the nitrating reactions. [ 11 ]
In industry, TNT is produced in a three-step process. First, toluene is nitrated with a mixture of sulfuric and nitric acid to produce mononitrotoluene (MNT). The MNT is separated and then renitrated to dinitrotoluene (DNT). In the final step, the DNT is nitrated to trinitrotoluene (TNT) using an anhydrous mixture of nitric acid and oleum . Nitric acid is consumed by the manufacturing process, but the diluted sulfuric acid can be reconcentrated and reused.
After nitration, TNT can either be purified by crystallization from an organic solvent or stabilized by a process called sulfitation, where the crude TNT is treated with aqueous sodium sulfite solution to remove less stable isomers of TNT and other undesired reaction products. The rinse water from sulfitation is known as red water and is a significant pollutant and waste product of TNT manufacture. [ 12 ]
Control of nitrogen oxides in feed nitric acid is very important because free nitrogen dioxide can result in oxidation of the methyl group of toluene. This reaction is highly exothermic and carries with it the risk of a runaway reaction leading to an explosion. [ citation needed ]
In the laboratory, 2,4,6-trinitrotoluene is produced by a two-step process. A nitrating mixture of concentrated nitric and sulfuric acids is used to nitrate toluene to a mixture of mono- and di-nitrotoluene isomers, with careful cooling to maintain temperature. The nitrated toluenes are then separated, washed with dilute sodium bicarbonate to remove oxides of nitrogen, and then carefully nitrated with a mixture of fuming nitric acid and sulfuric acid. [ citation needed ]
X-ray crystallography determined that each of the three planar nitro groups is substantially rotated out of the plane of the benzene ring. [ 13 ]
TNT is one of the most commonly used explosives for military, industrial, and mining applications. TNT has been used in conjunction with hydraulic fracturing (popularly known as fracking), a process used to acquire oil and gas from shale formations. The technique involves displacing and detonating nitroglycerin in hydraulically induced fractures followed by wellbore shots using pelletized TNT. [ 14 ]
TNT is valued partly because of its insensitivity to shock and friction, with reduced risk of accidental detonation compared to more sensitive explosives such as nitroglycerin . TNT melts at 80 °C (176 °F), far below the temperature at which it will spontaneously detonate, allowing it to be poured or safely combined with other explosives. TNT neither absorbs nor dissolves in water, which allows it to be used effectively in wet environments. To detonate, TNT must be triggered by a pressure wave from a starter explosive, called an explosive booster . [ 15 ]
Although blocks of TNT are available in various sizes (e.g. 250 g, 500 g, 1,000 g), it is more commonly encountered in synergistic explosive blends comprising a variable percentage of TNT plus other ingredients. Examples of explosive blends containing TNT include:
Upon detonation , TNT undergoes a decomposition equivalent to the reaction
plus some of the reactions
and
The reaction is exothermic but has a high activation energy in the gas phase (~62 kcal/mol). The condensed phases (solid or liquid) show markedly lower activation energies of roughly 35 kcal/mol due to unique bimolecular decomposition routes at elevated densities. [ 23 ] Because of the production of carbon , TNT explosions have a sooty appearance. Because TNT has an excess of carbon, explosive mixtures with oxygen-rich compounds can yield more energy per kilogram than TNT alone. During the 20th century amatol , a mixture of TNT with ammonium nitrate , was a widely used military explosive. [ 24 ]
TNT can be detonated with a high velocity initiator or by efficient concussion. [ 25 ] For many years, TNT used to be the reference point for the Figure of Insensitivity . TNT had a rating of exactly 100 on the "F of I" scale. The reference has since been changed to a more sensitive explosive called RDX , which has an F of I rating of 80. [ 26 ]
The energy density of TNT is used as a reference point for many other explosives, including nuclear weapons, as their energy content is measured in equivalent tonnes (metric tons, t) of TNT. The energy used by NIST to define the equivalent is 4.184 GJ /t or exactly 1 kcal /g. [ 27 ]
For safety assessments, it has been stated that the detonation of TNT, depending on circumstances, can release 2.673–6.702 GJ/t. [ 28 ]
The heat of combustion however is 14.5 GJ/t (14.5 MJ/kg or 4.027 kWh/kg), which requires that the carbon in TNT fully react with atmospheric oxygen, which does not occur in the initial event. [ 29 ]
For comparison, gunpowder contains 3 MJ/kg, dynamite contains 7.5 MJ/kg, and gasoline contains 47.2 MJ/kg (though gasoline requires an oxidant , so an optimized gasoline and O 2 mixture contains 10.4 MJ/kg). [ citation needed ]
Various methods can be used to detect TNT, including optical and electrochemical sensors and explosive-sniffing dogs. In 2013, researchers from the Indian Institutes of Technology using noble-metal quantum clusters could detect TNT at the sub- zeptomolar (10 −18 mol/m 3 ) level. [ 30 ]
TNT is poisonous, and skin contact can cause skin irritation, causing the skin to turn a bright yellow-orange color. During the First World War , female munition workers who handled the chemical found that their skin turned bright yellow, which resulted in their acquiring the nickname " canary girls " or simply "canaries". [ 31 ]
People exposed to TNT over a prolonged period tend to experience anemia and abnormal liver functions. Blood and liver effects, spleen enlargement and other harmful effects on the immune system have also been found in animals that ingested or breathed trinitrotoluene. There is evidence that TNT adversely affects male fertility . [ 32 ] TNT is listed as a possible human carcinogen , with carcinogenic effects demonstrated in animal experiments with rats, although effects upon humans so far amount to none (according to IRIS of March 15, 2000). [ 33 ] Consumption of TNT produces red urine through the presence of breakdown products and not blood as sometimes believed. [ 34 ]
Some military testing grounds are contaminated with wastewater from munitions programs, including contamination of surface and subsurface waters which may be colored pink because of the presence of TNT. Such contamination, called "pink water", may be difficult and expensive to remedy . [ citation needed ]
TNT is prone to exudation of dinitrotoluenes and other isomers of trinitrotoluene when projectiles containing TNT are stored at higher temperatures in warmer climates. Exudation of impurities leads to formation of pores and cracks (which in turn cause increased shock sensitivity). Migration of the exudated liquid into the fuze screw thread can form fire channels , increasing the risk of accidental detonation. Fuze malfunction can also result from the liquid migrating into the fuze mechanism. [ 35 ] Calcium silicate is mixed with TNT to mitigate the tendency towards exudation. [ 36 ]
Pink water and red water are two distinct types of wastewater related to trinitrotoluene. [ 37 ] Pink water is produced from equipment washing processes after munitions filling or demilitarization operations, [ 38 ] [ 39 ] and as such is generally saturated with the maximum amount of TNT that will dissolve in water (about 150 parts per million (ppm).) However it has an indefinite composition that depends on the exact process; in particular, it may also contain cyclotrimethylenetrinitramine (RDX) if the plant uses TNT/RDX mixtures, or HMX if TNT/HMX is used. Red water (also known as "Sellite water") is produced during the process used to purify the crude TNT. It has a complex composition containing more than a dozen aromatic compounds, but the principal components are inorganic salts ( sodium sulfate , sodium sulfite , sodium nitrite and sodium nitrate ) and sulfonated nitroaromatics . [ citation needed ]
Pink and red water are colorless at the time of generation; the color is produced by photolytic reactions under the influence of sunlight. Despite the names, red and pink water are not necessarily different shades; the color depends mainly on the duration of solar exposure. If exposed long enough, "pink" water may turn various shades of pink, red, rusty orange, or black. [ 39 ] [ 40 ]
Because of the toxicity of TNT, the discharge of pink water to the environment has been prohibited in the US and many other countries for decades, but ground contamination may exist in very old plants. However, RDX and tetryl contamination is usually considered more problematic, as TNT has very low soil mobility. Red water is significantly more toxic and as such it has always been considered hazardous waste. It has traditionally been disposed of by evaporation to dryness (as the toxic components are not volatile), followed by incineration. Much research has been conducted to develop better disposal processes. [ citation needed ]
Because of its suitability in construction and demolition, TNT has become the most widely used explosive and thus its toxicity is the most characterized and reported. Residual TNT from manufacture, storage, and use can pollute water, soil, the atmosphere , and the biosphere . [ 41 ]
The concentration of TNT in contaminated soil can reach 50 g/kg of soil, where the highest concentrations can be found on or near the surface. In September 2001, the United States Environmental Protection Agency (USEPA) declared TNT a pollutant whose removal is a priority. [ 42 ] The USEPA maintains that TNT levels in soil should not exceed 17.2 milligrams per kilogram of soil and 0.01 milligrams per litre of water. [ 43 ]
Dissolution is a measure of the rate that solid TNT in contact with water is dissolved. The relatively low aqueous solubility of TNT causes solid particles to be continuously released to the environment over extended periods of time. [ 44 ] Studies have shown that TNT dissolves more slowly in saline water than in freshwater. However, when salinity is altered, TNT dissolves at the same speed. [ 45 ] Because TNT is moderately soluble in water, it can migrate through subsurface soil, and cause groundwater contamination. [ 46 ]
Adsorption is a measure of the distribution between soluble and sediment adsorbed contaminants following attainment of equilibrium. TNT and its transformation products are known to adsorb to surface soils and sediments, where they undergo reactive transformation or remained stored. [ 47 ] The movement or organic contaminants through soils is a function of their ability to associate with the mobile phase (water) and a stationary phase (soil). Materials that associate strongly with soils move slowly through soil. The association constant for TNT with soil is 2.7 to 11 L/kg of soil. [ 48 ] This means that TNT has a one- to tenfold tendency to adhere to soil particulates than not when introduced into the soil. [ 44 ] Hydrogen bonding and ion exchange are two suggested mechanisms of adsorption between the nitro functional groups and soil colloids.
The number of functional groups on TNT influences the ability to adsorb into soil. Adsorption coefficient values have been shown to increase with an increase in the number of amino groups. Thus, adsorption of the TNT decomposition product 2,4-diamino-6-nitrotoluene (2,4-DANT) was greater than that for 4-amino-2,6-dinitrotoluene (4-ADNT), which was greater than that for TNT. [ 44 ] Lower adsorption coefficients for 2,6-DNT compared to 2,4-DNT can be attributed to the steric hindrance of the NO 2 group in the ortho position .
Research has shown that in freshwater environments, with high abundances of Ca 2+ , the adsorption of TNT and its transformation products to soils and sediments may be lower than observed in a saline environment, dominated by K + and Na + . Therefore, when considering the adsorption of TNT, the type of soil or sediment and the ionic composition and strength of the ground water are important factors. [ 49 ]
The association constants for TNT and its degradation products with clays have been determined. Clay minerals have a significant effect on the adsorption of energetic compounds. Soil properties, such as organic carbon content and cation exchange capacity have significant impacts on the adsorption coefficients.
Additional studies have shown that the mobility of TNT degradation products is likely to be lower "than TNT in subsurface environments where specific adsorption to clay minerals dominates the sorption process." [ 49 ] Thus, the mobility of TNT and its transformation products are dependent on the characteristics of the sorbent. [ 49 ] The mobility of TNT in groundwater and soil has been extrapolated from "sorption and desorption isotherm models determined with humic acids , in aquifer sediments, and soils". [ 49 ] From these models, it is predicted that TNT has a low retention and transports readily in the environment. [ 42 ]
Compared to other explosives, TNT has a higher association constant with soil, meaning it adheres more with soil than with water. Conversely, other explosives, such as RDX and HMX with low association constants (ranging from 0.06 to 7.3 L/kg and 0 to 1.6 L/kg respectively) can move more rapidly in water. [ 44 ]
TNT is a reactive molecule and is particularly prone to react with reduced components of sediments or photodegradation in the presence of sunlight. TNT is thermodynamically and kinetically capable of reacting with a wide number of components of many environmental systems. This includes wholly abiotic reactants, like hydrogen sulfide , Fe 2+ , or microbial communities, both oxic and anoxic and photochemical degradation. [ citation needed ]
Soils with high clay contents or small particle sizes and high total organic carbon content have been shown to promote TNT transformation. Possible TNT transformations include reduction of one, two, or three nitro-moieties to amines and coupling of amino transformation products to form dimers . Formation of the two monoamino transformation products, 2-ADNT and 4-ADNT, is energetically favored, and therefore is observed in contaminated soils and ground water. The diamino products are energetically less favorable, and even less likely are the triamino products. [ citation needed ]
The transformation of TNT is significantly enhanced under anaerobic conditions as well as under highly reducing conditions. TNT transformations in soils can occur both biologically and abiotically. [ 49 ]
Photolysis is a major process that impacts the transformation of energetic compounds. The alteration of a molecule in photolysis occurs by direct absorption of light energy or by the transfer of energy from a photosensitized compound. Phototransformation of TNT "results in the formation of nitrobenzenes , benzaldehydes , azodicarboxylic acids, and nitrophenols , as a result of the oxidation of methyl groups , reduction of nitro groups , and dimer formation." [ 44 ]
Evidence of the photolysis of TNT has been seen due to the color change to pink of TNT-containing wastewaters when exposed to sunlight. Photolysis is more rapid in river water than in distilled water. Ultimately, photolysis affects the fate of TNT primarily in the aquatic environment but could also affect the fate of TNT in soil when the soil surface is exposed to sunlight. [ 49 ]
The ligninolytic physiological phase and manganese peroxidase system of fungi can cause a very limited amount of mineralization of TNT in a liquid culture, though not in soil. An organism capable of the remediation of large amounts of TNT in soil has yet to be discovered. [ 50 ] Both wild and transgenic plants can phytoremediate explosives from soil and water. [ 51 ] | https://en.wikipedia.org/wiki/Pink_water |
The Pinkerton lecture series is held by the Institution of Engineering and Technology in commemoration and honour of John Pinkerton , the pivotal engineer who was involved with designing the UK's first business computer in 1951. The first lecture was held in 2000 and the event has taken place every year since then. | https://en.wikipedia.org/wiki/Pinkerton_Lecture |
The Pinner reaction refers to the acid catalysed reaction of a nitrile with an alcohol to form an imino ester salt ( alkyl imidate salt); this is sometimes referred to as a Pinner salt . [ 1 ] The reaction is named after Adolf Pinner , who first described it in 1877. [ 2 ] [ 3 ] [ 4 ] Pinner salts are themselves reactive and undergo additional nucleophilic additions to give various useful products: [ 5 ] [ 6 ]
Commonly, the Pinner salt itself is not isolated, with the reaction being continued to give the desired functional group (orthoester etc.) in one go. The imidium chloride salt is thermodynamically unstable, and low temperatures help prevent elimination to an amide and alkyl chloride . [ 8 ]
It should be appreciated that the Pinner reaction refers specifically to an acid catalyzed process, but that similar results can often be achieved using base catalysis. The two approaches can be complementary, with nitriles which are unreactive under acid conditions often giving better results in the presence of base, and vice versa. [ 9 ] The determining factor is typically how electron-rich or poor the nitrile is. For example: an electron-poor nitrile is a good electrophile (readily susceptible to attack from alkoxides etc.) but a poor nucleophile would typically be easier to protonate than to participate in the reaction and hence would be expected to react more readily under basic rather than acidic conditions. | https://en.wikipedia.org/wiki/Pinner_reaction |
The Pinner triazine synthesis describes the preparation of 2-hydroxyl-4,6-diaryl- s -triazines by reaction of aryl amidines and phosgene . This reaction may be extended to halogenated aliphatic amidines. [ 1 ] [ 2 ] [ 3 ]
This reaction was first reported by Adolf Pinner in 1890 [ 4 ] | https://en.wikipedia.org/wiki/Pinner_triazine_synthesis |
The Pinnick oxidation is an organic reaction by which aldehydes can be oxidized into their corresponding carboxylic acids using sodium chlorite (NaClO 2 ) under mild acidic conditions. It was originally developed by Lindgren and Nilsson. [ 1 ] The typical reaction conditions used today were developed by G. A. Kraus. [ 2 ] [ 3 ] H.W. Pinnick later demonstrated that these conditions could be applied to oxidize α,β-unsaturated aldehydes. [ 4 ] There exist many different reactions to oxidize aldehydes, but only a few are amenable to a broad range of functional groups . The Pinnick oxidation has proven to be both tolerant of sensitive functionalities and capable of reacting with sterically hindered groups. This reaction is especially useful for oxidizing α,β-unsaturated aldehydes, and another one of its advantages is its relatively low cost. [ 4 ] [ 5 ]
The proposed reaction mechanism involves chlorous acid as the active oxidant, which is formed under acidic conditions from chlorite.
First, the chlorous acid adds to the aldehyde. Then resulting structure undergoes a pericyclic fragmentation in which the aldehyde hydrogen is transferred to an oxygen on the chlorine, with the chlorine group released as hypochlorous acid (HOCl). [ 6 ]
The HOCl byproduct, itself a reactive oxidizing agent, can be a problem in several ways. [ 6 ] It can destroy the NaClO 2 reactant:
making it unavailable for the desired reaction. It can also cause other undesired side reactions with the organic materials. For example, HOCl can react with double bonds in the organic reactant or product via a halohydrin formation reaction .
To prevent interference from HOCl, a scavenger is usually added to the reaction to consume the HOCl as it is formed. For example, one can take advantage of the propensity of HOCl to undergo this addition reaction by adding a sacrificial alkene-containing chemical to the reaction mixture. This alternate substrate reacts with the HOCl, preventing the HOCl from undergoing reactions that interfere with the Pinnick reaction itself. 2-Methyl-2-butene is often used in this context:
Resorcinol and sulfamic acid are also common scavenger reagents. [ 6 ] [ 7 ]
Hydrogen peroxide (H 2 O 2 ) can be used as HOCl scavenger whose byproducts do not interfere in the Pinnick oxidation reaction:
In a weakly acidic condition, fairly concentrated (35%) H 2 O 2 solution undergoes a rapid oxidative reaction with no competitive reduction reaction of HClO 2 to form HOCl.
Chlorine dioxide reacts rapidly with H 2 O 2 to form chlorous acid .
Also the formation of oxygen gives good indication of the progress of the reaction. However, problems sometimes arise due to the formation of singlet oxygen in this reaction, which may oxidize organic materials (i.e. the Schenck ene reaction ). DMSO has been used instead of H 2 O 2 to oxidize reactions that do not produce great yields using only H 2 O 2 . Mostly electron rich aldehydes fall under this category. [ 7 ] (See Limitation below)
Also, solid-supported reagents such as phosphate-buffered silica gel supported by potassium permanganate and polymer-supported chlorite have been prepared and used to convert aldehydes to carboxylic acid without having to do conventional work-up procedures. The reaction involves the product to be trapped on silica gel as their potassium salts. Therefore, this procedure facilitates easy removal of neutral impurities by washing with organic solvents . [ 8 ]
The reaction is highly suited for substrates with many group functionalities. β-aryl-substituted α,β- unsaturated aldehydes works well with the reaction conditions. Triple bonds directly linked to aldehyde groups or in conjugation with other double bonds can also be subjected to the reaction. [ 7 ] [ 9 ] Hydroxides , epoxides , benzyl ethers , halides including iodides and even stannanes are quite stable in the reaction. [ 7 ] [ 9 ] [ 10 ] [ 11 ] The examples of the reactions shown below also show that the stereocenters of the α carbons remain intact while double bonds, especially trisubsituted double bonds do not undergo E / Z –isomerization in the reaction.
Lower yields are obtained for reactions involving aliphatic α,β-unsaturated and more hydrophilic aldehydes. Double bonds and electron-rich aldehyde substrates can lead to chlorination as an alternate reaction. The use of DMSO in these cases gives better yield. Unprotected aromatic amines and pyrroles are not well suited for the reactions either. In particular, chiral α-aminoaldehydes do not react well due to epimerization and because amino groups can be easily transformed to their corresponding N -oxides. Standard protective group approaches, such as the use of t -BOC , are a viable solution to these problems. [ 12 ]
Thioethers are also highly susceptible to oxidation. For example, Pinnick oxidation of thio anisaldehyde gives a high yield of carboxylic acid products, but with concomitant conversion of the thioether to the sulfoxide or sulfone . [ 7 ] | https://en.wikipedia.org/wiki/Pinnick_oxidation |
Pinning is a technique used when assembling large or heavy model kits (such as metal wargaming miniatures ) that involves drilling a hole in two pieces of the model to be joined, and using a "pin" to strengthen the bond when they are glued. Pinning is a useful technique for reinforcing joints and is essential when making models from parts that were not designed to go together, such as a miniature conversion . [ 1 ]
While models that are used for display purposes do not often require pinning, heavy models that are frequently handled (such as large metal miniatures used for wargaming) will often benefit from pinning to ensure that the model does not come apart. [ 2 ]
Some modellers also use Blu Tack or another temporary adhesive as an aid when pinning. [ 3 ]
This wargame -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pinning_(modelling) |
Pinning force is a force acting on a pinned object from a pinning center . In solid state physics , this most often refers to the vortex pinning, the pinning of the magnetic vortices ( magnetic flux quanta , Abrikosov vortices ) by different kinds of the defects in a type II superconductor . Important quantities are the individual maximal pinning force, which defines the depinning of a single vortex, and an average pinning force, which defines the depinning of the correlated vortex structures and can be associated with the critical current density (the maximal density of non-dissipative current). The interaction of the correlated vortex lattice with system of pinning centers forms the magnetic phase diagram of the vortex matter in superconductors . This phase diagram is especially rich for high temperature superconductors ( HTSC ) where the thermo-activation processes are essential.
The pinning mechanism is based on the fact that the amount of grain boundary area is reduced when a particle is located on a grain boundary. It is also assumed that particles are spherical and the particle-matrix interface is incoherent. When a moving grain boundary meets a particle at an angle β {\displaystyle \beta } , the particle exerts a pinning force F {\displaystyle F} on the grain boundary that is equal to F = 2 π σ cos β sin β {\displaystyle F=2\pi \sigma \cos \beta \sin \beta } ; with r {\displaystyle r} the particle radius and σ {\displaystyle \sigma } the energy per unit of grain boundary area. [ 1 ] | https://en.wikipedia.org/wiki/Pinning_force |
In a crystalline material, a dislocation is capable of traveling throughout the lattice when relatively small stresses are applied. This movement of dislocations results in the material plastically deforming . Pinning points in the material act to halt a dislocation's movement, requiring a greater amount of force to be applied to overcome the barrier. This results in an overall strengthening of materials .
Point defects (as well as stationary dislocations, jogs, and kinks) present in a material create stress fields within a material that disallow traveling dislocations to come into direct contact. Much like two particles of the same electric charge feel a repulsion to one another when brought together, the dislocation is pushed away from the already present stress field.
The introduction of atom 1 into a crystal of atom 2 creates a pinning point for multiple reasons. An alloying atom is by nature a point defect, thus it must create a stress field when placed into a foreign crystallographic position, which could block the passage of a dislocation. However, it is possible that the alloying material is approximately the same size as the atom that is replaced, and thus its presence would not stress the lattice (as occurs in cobalt alloyed nickel). The different atom would, though, have a different elastic modulus , which would create a different terrain for the moving dislocation. A higher modulus would look like an energy barrier, and a lower like an energy trough – both of which would stop its movement.
The precipitation of a second phase within the lattice of a material creates physical blockades through which a dislocation cannot pass. The result is that the dislocation must bend (which requires greater energy, or a greater stress to be applied) around the precipitates, which inevitably leaves residual dislocation loops encircling the second phase material and shortens the original dislocation.
Dislocations require proper lattice ordering to move through a material. At grain boundaries , there is a lattice mismatch, and every atom that lies on the boundary is uncoordinated . This stops dislocations that encounter the boundary from moving. | https://en.wikipedia.org/wiki/Pinning_points |
In cellular biology , pinocytosis , otherwise known as fluid endocytosis and bulk-phase pinocytosis , is a mode of endocytosis in which small molecules dissolved in extracellular fluid are brought into the cell through an invagination of the cell membrane , resulting in their containment within a small vesicle inside the cell. These pinocytotic vesicles then typically fuse with early endosomes to hydrolyze (break down) the particles. [ citation needed ]
Pinocytosis is variably subdivided into categories depending on the molecular mechanism and the fate of the internalized molecules.
In humans, this process occurs primarily for absorption of fat droplets. In endocytosis the cell plasma membrane extends and folds around desired extracellular material, forming a pouch that pinches off creating an internalized vesicle. The invaginated pinocytosis vesicles are much smaller than those generated by phagocytosis . The vesicles eventually fuse with the lysosome, whereupon the vesicle contents are digested. [ 1 ] Pinocytosis involves a considerable investment of cellular energy in the form of ATP. [ 1 ]
Pinocytosis is used primarily for clearing extracellular fluids (ECF) and as part of immune surveillance. [ 2 ] In contrast to phagocytosis , it generates very small amounts of ATP from the wastes of alternative substances such as lipids (fat) [ citation needed ] . Unlike receptor-mediated endocytosis , pinocytosis is nonspecific in the substances that it does transport: the cell takes in surrounding fluids, including all solutes present. [ 1 ]
The word pinocytosis ( / ˌ p ɪ n ə s aɪ ˈ t oʊ s ɪ s , ˌ p aɪ -, - n oʊ -, - s ə -/ [ 3 ] [ 4 ] [ 5 ] ) uses combining forms of pino- + cyto- + -osis , all Neo-Latin from Greek , reflecting píno , to drink, and cytosis . The term was proposed by W. H. Lewis in 1931. [ 6 ]
Non-specific, adsorptive pinocytosis is a form of endocytosis , a process in which small particles are taken in by a cell by splitting off small vesicles from the cell membrane. [ 7 ] Cationic proteins bind to the negative cell surface and are taken up via the clathrin -mediated system, thus the uptake is intermediate between receptor-mediated endocytosis and non-specific, non-adsorptive pinocytosis. The clathrin-coated pits occupy about 2% of the surface area of the cell and only last about a minute, with an estimated 2500 leaving the average cell surface each minute. The clathrin coats are lost almost immediately, and the membrane is subsequently recycled to the cell surface.
Macropinocytosis is a clathrin-independent endocytic mechanism that can be activated in practically all animal cells, resulting in uptake. In most cell types, it does not occur continuously but rather is induced for a limited time in response to cell-surface receptor activation by specific cargoes, including growth factors , ligands of integrins , and apoptotic cell remnants. These ligands activate a complex signaling pathway, resulting in a change in actin dynamics and the formation of cell-surface protrusions of filopodia and lamellopodia , commonly called ruffles . When ruffles collapse back onto the membrane, large fluid-filled endocytic vesicles form called macropinosomes , which can transiently increase the bulk fluid uptake of a cell by up to tenfold. Macropinocytosis is a solely degradative pathway: macropinosomes acidify and then fuse with late endosomes or endolysosomes, without recycling their cargo back to the plasma membrane. [ 8 ]
Some bacteria and viruses have evolved to induce macropinocytosis as a mechanism for entering host cells. Some of these can stop the degradation processes in order to survive inside the macropinosome, which may transform into smaller and long-lasting vacuoles containing the viruses or bacteria (some of which may replicate inside), or simply escape through the wall of the macropinosome when inside. For example, the gut pathogen Salmonella typhimurium injects toxins into the host cell in order to induce macropinocytosis as a form of uptake, inhibits the degradation of the macropinosome, and forms a salmonella-containing vacuole, or SCV, wherein it can replicate. [ 9 ] | https://en.wikipedia.org/wiki/Pinocytosis |
In information theory , Pinsker's inequality , named after its inventor Mark Semenovich Pinsker , is an inequality that bounds the total variation distance (or statistical distance) in terms of the Kullback–Leibler divergence .
The inequality is tight up to constant factors. [ 1 ]
Pinsker's inequality states that, if P {\displaystyle P} and Q {\displaystyle Q} are two probability distributions on a measurable space ( X , Σ ) {\displaystyle (X,\Sigma )} , then
where
is the total variation distance (or statistical distance) between P {\displaystyle P} and Q {\displaystyle Q} and
is the Kullback–Leibler divergence in nats . When the sample space X {\displaystyle X} is a finite set, the Kullback–Leibler divergence is given by
Note that in terms of the total variation norm ‖ P − Q ‖ {\displaystyle \|P-Q\|} of the signed measure P − Q {\displaystyle P-Q} , Pinsker's inequality differs from the one given above by a factor of two:
A proof of Pinsker's inequality uses the partition inequality for f -divergences .
Note that the expression of Pinsker inequality depends on what basis of logarithm is used in the definition of KL-divergence. D K L {\displaystyle D_{KL}} is defined using ln {\displaystyle \ln } (logarithm in base e {\displaystyle e} ), whereas D {\displaystyle D} is typically defined with log 2 {\displaystyle \log _{2}} (logarithm in base 2). Then,
Given the above comments, there is an alternative statement of Pinsker's inequality in some literature that relates information divergence to variation distance:
i.e.,
in which
is the (non-normalized) variation distance between two probability density functions p {\displaystyle p} and q {\displaystyle q} on the same alphabet X {\displaystyle {\mathcal {X}}} . [ 2 ]
This form of Pinsker's inequality shows that "convergence in divergence" is a stronger notion than "convergence in variation distance".
A simple proof by John Pollard is shown by letting r ( x ) = P ( x ) / Q ( x ) − 1 ≥ − 1 {\displaystyle r(x)=P(x)/Q(x)-1\geq -1} :
Here Titu's lemma is also known as Sedrakyan's inequality .
Note that the lower bound from Pinsker's inequality is vacuous for any distributions where D K L ( P ∥ Q ) > 2 {\displaystyle D_{\mathrm {KL} }(P\parallel Q)>2} , since the total variation distance is at most 1 {\displaystyle 1} . For such distributions, an alternative bound can be used, due to Bretagnolle and Huber [ 3 ] (see, also, Tsybakov [ 4 ] ):
Pinsker first proved the inequality with a greater constant. The inequality in the above form was proved independently by Kullback , Csiszár , and Kemperman . [ 5 ]
A precise inverse of the inequality cannot hold: for every ε > 0 {\displaystyle \varepsilon >0} , there are distributions P ε , Q {\displaystyle P_{\varepsilon },Q} with δ ( P ε , Q ) ≤ ε {\displaystyle \delta (P_{\varepsilon },Q)\leq \varepsilon } but D K L ( P ε ∥ Q ) = ∞ {\displaystyle D_{\mathrm {KL} }(P_{\varepsilon }\parallel Q)=\infty } . An easy example is given by the two-point space { 0 , 1 } {\displaystyle \{0,1\}} with Q ( 0 ) = 0 , Q ( 1 ) = 1 {\displaystyle Q(0)=0,Q(1)=1} and P ε ( 0 ) = ε , P ε ( 1 ) = 1 − ε {\displaystyle P_{\varepsilon }(0)=\varepsilon ,P_{\varepsilon }(1)=1-\varepsilon } . [ 6 ]
However, an inverse inequality holds on finite spaces X {\displaystyle X} with a constant depending on Q {\displaystyle Q} . [ 7 ] More specifically, it can be shown that with the definition α Q := min x ∈ X : Q ( x ) > 0 Q ( x ) {\displaystyle \alpha _{Q}:=\min _{x\in X:Q(x)>0}Q(x)} we have for any measure P {\displaystyle P} which is absolutely continuous to Q {\displaystyle Q}
As a consequence, if Q {\displaystyle Q} has full support (i.e. Q ( x ) > 0 {\displaystyle Q(x)>0} for all x ∈ X {\displaystyle x\in X} ), then
Lemma 1.1 (Pinsker’s inequality) Let P {\displaystyle P} and Q {\displaystyle Q} be two distributions defined on the universe U {\displaystyle U} . Then, D ( P | | Q ) ≥ 1 2 ln 2 ⋅ | | P − Q | | 1 2 . {\displaystyle D(P||Q)\geq {\frac {1}{2\ln 2}}\cdot ||P-Q||_{1}^{2}.} [ 8 ]
Proof: A special case:
P = { 1 , w.p. p 0 , w.p. 1 − p {\displaystyle P={\begin{cases}1,&{\text{w.p. }}p\\0,&{\text{w.p. }}1-p\end{cases}}}
and,
Q = { 1 , w.p. q 0 , w.p. 1 − q {\displaystyle Q={\begin{cases}1,&{\text{w.p. }}q\\0,&{\text{w.p. }}1-q\end{cases}}}
We assume p ≥ q {\displaystyle p\geq q} (other case is similar), and let
f ( p , q ) = p log p q + ( 1 − p ) log 1 − p 1 − q − 1 2 ln 2 ( 2 ( p − q ) ) 2 . {\displaystyle f(p,q)=p\log {\frac {p}{q}}+(1-p)\log {\frac {1-p}{1-q}}-{\frac {1}{2\ln 2}}(2(p-q))^{2}.}
Since
∂ f ∂ q = − p − q ln 2 ( 1 q ( 1 − q ) − 4 ) ≤ 0 , {\displaystyle {\frac {\partial f}{\partial q}}=-{\frac {p-q}{\ln 2}}\left({\frac {1}{q(1-q)}}-4\right)\leq 0,}
and f = 0 {\displaystyle f=0} when q = p {\displaystyle q=p} , we conclude that f ( p , q ) ≥ 0 {\displaystyle f(p,q)\geq 0} where q ≤ p . {\displaystyle q\leq p.} Thus we have that D ( P | | Q ) ≥ 1 2 ln 2 | | P − Q | | 1 2 {\displaystyle D(P||Q)\geq {\tfrac {1}{2\ln 2}}||P-Q||_{1}^{2}} for this special case.
General case: Let P {\displaystyle P} and Q {\displaystyle Q} be distributions on U . {\displaystyle U.} Let A ⊂ U {\displaystyle A\subset U} be
A = { x | p ( x ) ≥ q ( x ) } . {\displaystyle A=\{x|p(x)\geq q(x)\}.}
and P A {\displaystyle P_{A}} and Q A {\displaystyle Q_{A}} be
P A = { 1 , w.p. ∑ x ∈ A p ( x ) 0 , w.p. ∑ x ∉ A p ( x ) {\displaystyle P_{A}={\begin{cases}1,&{\text{w.p. }}\sum \limits _{x\in A}p(x)\\0,&{\text{w.p. }}\sum \limits _{x\not \in A}p(x)\end{cases}}}
Q A = { 1 , w.p. ∑ x ∈ A q ( x ) 0 , w.p. ∑ x ∉ A q ( x ) {\displaystyle Q_{A}={\begin{cases}1,&{\text{w.p. }}\sum \limits _{x\in A}q(x)\\0,&{\text{w.p. }}\sum \limits _{x\not \in A}q(x)\end{cases}}}
Then,
| | P − Q | | 1 = ∑ x | p ( x ) − q ( x ) | = ∑ x ∈ A ( p ( x ) − q ( x ) ) + ∑ x ∉ A ( q ( x ) − p ( x ) ) = | ∑ x ∈ A p ( x ) − ∑ x ∈ A q ( x ) | + | ∑ x ∉ A p ( x ) − ∑ x ∉ A q ( x ) | | | P − Q | | 1 = | | P A − Q A | | 1 (1) {\displaystyle {\begin{aligned}||P-Q||_{1}&=\sum \limits _{x}|p(x)-q(x)|\\&=\sum \limits _{x\in A}(p(x)-q(x))+\sum \limits _{x\notin A}(q(x)-p(x))\\&=\left|\sum \limits _{x\in A}p(x)-\sum \limits _{x\in A}q(x)\right|+\left|\sum \limits _{x\notin A}p(x)-\sum \limits _{x\notin A}q(x)\right|\\||P-Q||_{1}&=||P_{A}-Q_{A}||_{1}&{\text{(1)}}\end{aligned}}}
Define a random variable Z {\displaystyle Z} as Z = { 1 , if x ∈ A 0 , if x ∉ A . {\displaystyle Z={\begin{cases}1,&{\text{if }}x\in A\\0,&{\text{if }}x\notin A\end{cases}}.} We have that D ( P | | Q ) = D ( P ( Z ) | | Q ( Z ) ) + D ( P | | Q | Z ) . {\displaystyle D(P||Q)=D(P(Z)||Q(Z))+D(P||Q|Z).} Since D ( P ( Z ) | | Q ( Z ) ) = D ( P A | | Q A ) {\displaystyle D(P(Z)||Q(Z))=D(P_{A}||Q_{A})} and D ( P | | Q | Z ) ≥ 0 , {\displaystyle D(P||Q|Z)\geq 0,} we have
D ( P | | Q ) ≥ D ( P A | Q A ) ≥ 1 2 ln 2 ⋅ | | P A − Q A | | 1 2 (use the special case) = 1 2 ln 2 ⋅ | | P − Q | | 1 2 (use equation 1) {\displaystyle {\begin{aligned}D(P||Q)&\geq D(P_{A}|\ Q_{A})\\&\geq {\frac {1}{2\ln 2}}\cdot ||P_{A}-Q_{A}|{|_{1}}^{2}&{\text{(use the special case)}}\\&={\frac {1}{2\ln 2}}\cdot ||P-Q|{|_{1}}^{2}&{\text{(use equation 1)}}\end{aligned}}}
■ | https://en.wikipedia.org/wiki/Pinsker's_inequality |
Piobert's law applies to the reaction of solid propellant grains to generate hot gas. It is stated: "Burning takes place by parallel layers where the surface of the grain regresses, layer by layer, normal to the surface at every point." [ 1 ]
The law was devised by French general Guillaume Piobert (in French) in 1839 to explain the behavior of gunpowder , but it has subsequently been applied to other solid propellants. Description of the reaction as burning may cause confusion with simple atmospheric combustion of solid materials where a similar reaction progression may be attributed to availability of the oxygen reactant only at the surface of the solid being consumed by the reaction. In the case of single-phase propellant grains, the progression is attributed to heat transfer from the surface of the solid of energy necessary to initiate the reaction. The heat transfer rate increases with pressure; and smokeless powder reaction rates vary with pressure as described by Paul Vieille in 1893. [ 1 ]
Studies of solid single- and double-base propellant reactions suggest a series of zones or phases as the reaction proceeds from the surface into the solid. The deepest portion of the solid experiencing heat transfer melts and begins phase transition from solid to gas in a foam zone . The gaseous propellant decomposes into simpler molecules in a surrounding fizz zone . Energy is released in a luminous outer flame zone where the simpler gas molecules react to form conventional combustion products like steam and carbon monoxide . Propellants designed for a minimum heat transfer pressure may fail to sustain the flame zone at lower pressures. [ 2 ]
G. Piobert, Mémoire sur les poudres de guerre, des différents procédés de frabrication (1844) | https://en.wikipedia.org/wiki/Piobert's_law |
A pioneer ( / ˌ p aɪ . ə ˈ n ɪər / ) is a soldier employed to perform engineering and construction tasks. The term is in principle similar to sapper or combat engineer . Pioneers were originally part of the artillery branch of European armies. Subsequently, they formed part of the engineering branch, the logistic branch, part of the infantry, or even comprised a branch in their own right.
Historically, the primary role of pioneer units was to assist other arms in tasks such as the construction of field fortifications , military camps , bridges and roads. [ 1 ] Prior to and during the First World War , pioneers were often engaged in the construction and repair of military railways . [ 2 ] During World War II , pioneer units were used extensively by all major forces, both on the front line and in supporting roles.
During the 20th century, British Commonwealth military forces came to distinguish between small units of " assault pioneers " belonging to infantry regiments and separate pioneer units (as in the former Royal Pioneer Corps ). The United States Marine Corps has sometimes organized its sappers into "Pioneer Battalions". [ 3 ] The arrival of the military engineering vehicle and the deployment of weapons of mass destruction vastly expanded capabilities and complicated mission-profiles of modern pioneer units.
The word pioneer is originally from France. The word ( French : pionnier ) was borrowed into English, from Old French pionnier , which meant a "foot soldier", from the root 'peon' [ 4 ] recorded in 1523. [ 5 ] It was used in a military sense as early as 1626–1627. [ 6 ] In the late 18th century, Captain George Smith defined the term as:
PIONEERS, in war-time, are such as are commanded in from the country, to march with an army, for mending the ways, for working on entrenchments, fortifications, and for making mines and approaches: the soldiers are likewise employed in all these things. Most of the foreign regiments of artillery have half a company of pioneers, well instructed in that important branch of duty. Our regiments of infantry and cavalry have 3 or 4 pioneers each, provided with aprons, hatchets, saws, spades, and pick-axes. [ 7 ]
Extensive use was made of pioneers in the British Indian Army because of the demands of campaigning in difficult terrain with little or no infrastructure . In 1780, two companies of pioneers were raised in Madras, increasing to 16 in 1803 divided into two battalions. Bombay and Bengal pioneers were formed during the same period. In the late nineteenth century, a number of existing Indian infantry regiments took the title and the construction role of pioneers. [ 8 ] The twelve Indian Pioneer regiments in existence in 1914 were trained and equipped for road, rail and engineering work, as well as for conventional infantry service. While this dual function did not qualify them to be regarded as elite units, the frequency with which they saw active service made postings to pioneer regiments popular with British officers. [ 9 ]
Prior to World War I, each sepoy in a Pioneer regiment carried a pickaxe or a light spade in special leather equipment as well as a rifle and bayonet. NCOs and buglers carried axes, saws and billhooks. Heavier equipment, such as explosives, was carried by mule. The unit was therefore well equipped for simple field engineering tasks, as well as being able to defend itself in hostile territory. During the War, the increased specialisation required of Pioneers made them too valuable to use as regular assault infantry. Accordingly, in 1929, the Pioneer regiments were taken out of the line infantry and grouped into the Corps of Madras Pioneers (four battalions), the Corps of Bombay Pioneers (four battalions), the Corps of Sikhs Pioneers (four battalions), and the Corps of Hazara Pioneers (one battalion). [ 10 ]
All four Pioneer Corps were disbanded in 1933 and their personnel mostly transferred into the Corps of Sappers and Miners, whose role they had come to parallel. It was concluded that the Pioneer battalions had become less technically effective than the Sappers and Miners, but too well trained in specialist functions to warrant being used as ordinary infantry. In addition, their major role of frontier road building had now been allocated to civilian workers. [ 11 ] An Indian Pioneer Corps was re-established in 1943.
Historically, British infantry regiments maintained small units of pioneers for heavy work and engineering, especially for clearing paths through forests and for leading assaults on fortifications. These units evolved into assault pioneers . They also inspired the creation of the Royal Pioneer Corps.
During World War I, on paper at least, each division was allocated a pioneer infantry battalion, who in addition to being trained infantry were able to conduct pioneer duties. These pioneer battalions were raised and numbered within the existing infantry regiments; where possible recruits were men who possessed transferable skills from civilian life.
The Royal Pioneer Corps was a British Army combatant corps used for light engineering tasks. The Royal Pioneer Corps was raised on 17 October 1939 as the Auxiliary Military Pioneer Corps. It was renamed the Pioneer Corps on 22 November 1940. It was renamed the Royal Pioneer Corps on 28 November 1946. On 5 April 1993, the Royal Pioneer Corps united with other units to form the Royal Logistic Corps .
The specialist pioneer units in the Royal Logistic Corps, 23 Pioneer Regiment , based at St David's Barracks at Bicester , and 168 Pioneer Regiment , headquartered in Prince William of Gloucester Barracks at Grantham , were disbanded in 2014, as part of the Army 2020 re-organisation.
The ARRC Support Battalion is based at Imjin Barracks , Innsworth (until June 2010, it was at Rheindahlen Military Complex , Germany ) [ 12 ]
All British infantry regiments still maintain assault pioneer units. The Pioneer Sergeant is the only rank allowed to wear a beard on parade. [ 13 ]
The Israeli army has an infantry brigade called the Fighting Pioneer Youth , in Hebrew Noar Halutzi Lohem or just "Nahal" . The title of Israeli military pioneers is a back-derivation from the civilian term . The Israeli army's pioneers were formed in 1948 from Jewish civilian pioneers, i.e. settlers, who were permitted to combine military service and farming.
During World War I, Australia raised six pioneer battalions within the First Australian Imperial Force (1st AIF) for service on the Western Front, one per division: [ 19 ]
In World War II, four pioneer battalions were raised as part of the Second Australian Imperial Force (2nd AIF): [ 20 ]
Other World War II pioneer units:
For Indian Army Pioneer Corps, see also Indian Army Pioneer Corps
British Indian Army Pioneer Battalions enlisted, drilled and trained as any other native infantry battalion of the line, but received additional construction training. | https://en.wikipedia.org/wiki/Pioneer_(military) |
Pioneer factors are transcription factors that can directly bind condensed chromatin . They can have positive and negative effects on transcription and are important in recruiting other transcription factors and histone modification enzymes as well as controlling DNA methylation . They were first discovered in 2002 as factors capable of binding to target sites on nucleosomal DNA in compacted chromatin and endowing competency for gene activity during hepatogenesis. [ 1 ] Pioneer factors are involved in initiating cell differentiation and activation of cell-specific genes . This property is observed in histone fold-domain containing transcription factors (fork head box (FOX) [ 2 ] and NF-Y [ 3 ] ) and other transcription factors that use zinc finger(s) for DNA binding (Groucho TLE, Gal4 , and GATA). [ 2 ] [ 4 ]
The eukaryotic cell condenses its genome into tightly packed chromatin and nucleosomes . This ability saves space in the nucleus for only actively transcribed genes and hides unnecessary or detrimental genes from being transcribed. Access to these condensed regions is done by chromatin remodelling by either balancing histone modifications or directly with pioneer factors that can loosen the chromatin themselves or as a flag recruiting other factors. Pioneer factors are not necessarily required for assembly of the transcription apparatus and may dissociate after being replaced by other factors.
Pioneer factors can also actively affect transcription by directly opening up condensed chromatin in an ATP-independent process. [ 2 ] [ 3 ] This is a common trait of fork head box factors (which contain a winged helix DNA-binding domain that mimics the DNA-binding domain of the linker H1 histone [ 5 ] ), and NF-Y (whose NF-YB and NF-YC subunits contain histone-fold domains similar to those of the core histones H2A/H2B [ 6 ] ).
The similarity to histone H1 explains how fork head factors are able to bind chromatin by interacting with the major groove of only the one available side of DNA wrapped around a nucleosome. [ 5 ] [ 7 ] Fork head domains also have a helix that confers sequence specificity unlike linker histone. [ 5 ] [ 8 ] The C terminus is associated with higher mobility around the nucleosome than linker histone, displacing it and rearranging nucleosomal landscapes effectively. [ 7 ] This active re-arrangement of the nucleosomes allows for other transcription factors to bind the available DNA. In thyroid cell differentiation FoxE binds to compacted chromatin of the thyroid peroxidase promoter and opens it for NF1 binding. [ 9 ]
NF-Y is a heterotrimeric complex composed of NF-YA , NF-YB , and NF-YC subunits. The key structural feature of the NF-Y/DNA complex is the minor-groove interaction of its DNA binding domain-containing subunit NF-YA , which induces an ~80° bend in the DNA. NF-YB and NF-YC interact with DNA through non-specific histone-fold domain-DNA contacts. [ 6 ] NF-YA's unique DNA-binding mode and NF-YB/NF-YC's nucleosome-like properties of non-specific DNA binding impose sufficient spatial constraints to induce flanking nucleosomes to slide outward, making nearby recognition sites for other transcription factors accessible. [ 3 ]
Pioneer factors can function passively, by acting as a bookmark for the cell to recruit other transcription factors to specific genes in condensed chromatin. This can be important for priming the cell for a rapid response as the enhancer is already bound by a pioneer transcription factor giving it a head start towards assembling the transcription preinitiation complex . Hormone responses are often quickly induced in the cell using this priming method such as with the estrogen receptor . [ 10 ] Another form of priming is when an enhancer is simultaneously bound by activating and repressing pioneer factors. This balance can be tipped by dissociation of one of the factors. In hepatic cell differentiation the activating pioneer factor FOXA1 recruits a repressor , grg3, that prevents transcription until the repressor is down-regulated later on in the differentiation process. [ 11 ] In a direct role pioneer factors can bind an enhancer and recruit activation complex that will modify the chromatin directly. The change in the chromatin changes the affinity, decreasing the affinity of the pioneer factor such that it is replaced by a transcription factor that has a higher affinity. This is a mechanism for the cell to switch a gene on was observed with glucocorticoid receptor recruiting modification factors that then modify the site to bind activated estrogen receptor which was coined as a “bait and switch” mechanism. [ 12 ]
Pioneer factors can exhibit their greatest range of effects on transcription through the modulation of epigenetic factors by recruiting activating or repressing histone modification enzymes and controlling CpG methylation by protecting specific cysteine residues. This has effects on controlling the timing of transcription during cell differentiation processes.
Histone modification is a well-studied mechanism to transiently adjust chromatin density. Pioneer factors can play a role in this by binding specific enhancers and flagging histone modification enzymes to that specific gene. Repressive pioneer factors can inhibit transcription by recruiting factors that modify histones that further tighten the chromatin. This is important to limit gene expression to specific cell types and has to be removed only when cell differentiation begins. FoxD3 has been associated as a repressor of both B-cell and melanocytic cell differentiation pathways, maintaining repressive histone modifications where bound, that have to be overcome to start differentiation. [ 13 ] [ 14 ] Pioneer factors can also be associated with recruiting transcription-activating histone modifications. Enzymes that modify H3K4 with mono and di-methylation are associated with increasing transcription and have been shown to bind pioneer factors. [ 10 ] In B cell differentiation PU.1 is necessary to signal specific histones for activating H3K4me1 modifications that differentiate hematopoietic stem cells into either the B-cell or macrophage lineage. [ 15 ] FoxA1 binding induces HSK4me2 during neuronal differentiation of pluripotent stem cells [ 16 ] as well as the loss of DNA methylation. [ 17 ] SOX9 recruits histone modification enzymes MLL3 and MLL4 to deposit H3K4me1 prior to the opening of enhancers in developing hair follicle and basal cell carcinoma. [ 18 ]
Pioneer factors can also affect transcription and differentiation through the control of DNA methylation. Pioneer factors that bind to CpG islands and cytosine residues block access to methyltransferases. Many eukaryotic cells have CpG islands in their promoters that can be modified by methylation having adverse effects on their ability to control transcription. [ 19 ] This phenomenon is also present in promoters without CpG islands where single cytosine residues are protected from methylation until further cell differentiation. An example is FoxD3 preventing methylation of a cytosine residue in Alb1 enhancer, acting as a place holder for FoxA1 later in hepatic [ 20 ] as well as in CpG islands of genes in chronic lymphocytic leukemia . [ 21 ] For stable control of methylation state the cytosine residues are covered during mitosis , unlike most other transcription factors, to prevent methylation. Studies have shown that during mitosis 15% of all interphase FoxA1 binding sites were bound. [ 22 ] The protection of cytosine methylation can be quickly removed allowing for rapid induction when a signal is present.
A well studied pioneer factor family is the Groucho-related (Gro/TLE/Grg) transcription factors that often have a negative effect on transcription. These chromatin binding domains can span up to 3-4 nucleosomes. These large domains are scaffolds for further protein interactions and also modify the chromatin for other pioneer factors such as FoxA1 which has been shown to bind to Grg3. [ 23 ] Transcription factors with zinc finger DNA binding domains, such as the GATA family and glucocorticoid receptor. [ 10 ] The zinc finger domains do not appear to bind nucleosomes well and can be displaced by FOX factors. [ 22 ]
In the skin epidermis, SOX family transcription factor, SOX9 , also behaves as a pioneer factor that governs hair follicle cell fate and can reprogram epidermal stem cells to a hair follicle fate. [ 24 ]
The ability of pioneer factors to respond to extracellular signals to differentiate cell type has been studied as a potential component of hormone-dependent cancers. Hormones such as estrogen and IGFI are shown to increase pioneer factor concentration leading to a change in transcription. [ 25 ] Known pioneer factors such as FoxA1, PBX1 , TLE, AP2 ɣ , GATA factors 2 / 3 / 4 , and PU.1 have been associated with hormone-dependent cancer . FoxA1 is necessary for estrogen and androgen mediated hepatocarcinogenesis and is a defining gene for ER + luminal breast cancer, as is another pioneer factor GATA3. [ 10 ] [ 25 ] FOXA1 particularly is expressed in 90% of breast cancer metastases and 89% of metastatic prostate cancers. [ 25 ] [ 26 ] In the breast cancer cell line, MCF-7 , it was found that FoxA1 was bound to 50% of estrogen receptor binding sites independent of estrogen presence. High expression of pioneer factors is associated with poor prognosis with the exception of breast cancer where FoxA1 is associated with a stronger outcome. [ 25 ] The correlation between pioneer factors and cancer has led to prospective therapeutic targeting. In knockdown studies in the MCF-7 breast cancer cell line it was found that decreasing pioneer factors FoxA1 and AP2 ɣ decreased ER signalling. [ 4 ] [ 25 ] Other fork head proteins have been associated with cancer, including FoxO3 and FoxM that repress the cell survival pathways Ras and PPI3K/AKT/IKK. [ 27 ] Drugs such as Paclitaxel , Imatinib , and doxorubicin which activate FoxO3a or its targets are being used. Modification to modulate related factors with pioneer activity is a topic of interest in the early stages as knocking down pioneer factors may have toxic effects through alteration of the lineage pathways of healthy cells. [ 25 ] | https://en.wikipedia.org/wiki/Pioneer_factor |
Pioneer species are resilient species that are the first to colonize barren environments , or to repopulate disrupted biodiverse steady-state ecosystems as part of ecological succession . Various kinds of events can create good conditions for pioneers, including disruption by natural disasters , such as wildfire , flood , mudslide , lava flow or a climate-related extinction event , [ 1 ] or by anthropogenic habitat destruction , such as through land clearance for agriculture or construction or industrial damage. Pioneer species play an important role in creating soil in primary succession , and stabilizing soil and nutrients in secondary succession . [ 2 ]
For humans, because pioneer species quickly occupy disrupted spaces, they are sometimes treated as weeds or nuisance wildlife , such as the common dandelion or stinging nettle . [ 3 ] [ 2 ] Even though humans have mixed relationships with these plants, these species tend to help improve the ecosystem because they can break up compacted soils and accumulate nutrients that help with a transition back to a more mature ecosystem. [ 4 ] [ 5 ] [ 2 ] In human-managed ecological restoration or agroforestry , trees and herbaceous pioneers can be used to restore soil qualities and provide shelter for slower growing or more demanding plants. [ 5 ] [ 6 ] [ 7 ] Some systems use introduced species to restore the ecosystem, [ 2 ] or for environmental remediation . [ 8 ] The durability of pioneer species can also make them potential invasive species . [ 9 ] [ 2 ] [ 10 ]
As uninhabited or disrupted land may have thin, poor quality soils with few nutrients, pioneer species are often hardy plants with adaptations such as long roots, root nodes containing nitrogen-fixing bacteria , and leaves that employ transpiration . These plants are often photosynthetic , as no other source of energy except light is typically available in the early stages of succession . Some lichens can grow on rocks without soil, and may be among the first pioneer species, breaking down the rocks into soil for plants. [ 11 ]
The plants that are often pioneer species tend to be wind-pollinated rather than insect-pollinated , as insects are unlikely to be present in the usually barren conditions in which pioneer species grow. Pioneer species also tend to reproduce asexually altogether, as the extreme or barren conditions make it more favourable to reproduce asexually in order to increase reproductive success rather than invest energy into sexual reproduction . Pioneer species eventually die, create plant litter , and break down as " leaf mold " after some time, making new soil for secondary succession , and releasing nutrients for small fish and aquatic plants in adjacent bodies of water. [ 12 ]
Some examples of pioneering plant species in various habitats:
Pioneering fauna will colonize an area only after flora and fungi have inhabited the area. Soil fauna, ranging from microscopic protists to larger invertebrates , have a role in soil formation and nutrient cycling . Bacteria and fungi are the most important groups in the breakdown of organic detritus left by primary producing plants such as skeletal soil , moss and algae . Soil invertebrates enhance fungal activity by breaking down detritus. As soil develops, earthworms and ants alter soil characteristics. Worm burrows aerate soil and ant hills alter sediment particle size dispersal, altering soil character profoundly.
Though vertebrates in general are not considered pioneer species, there are exceptions. Natterjack toads ( Epidalea calamita ) are specialists in open, sparsely vegetated habitats which may be at an early seral stage . [ 15 ] Wide-ranging generalists visit early succession stage habitats, but are not obligate species of those habitats because they use a mosaic of different habitats.
Vertebrates can affect early seral stages. Herbivores may alter plant growth. Fossorial mammals could alter soil and plant community development. In a profound example, a seabird colony transfers considerable nitrogen into infertile soils, thereby altering plant growth. A keystone species may facilitate the introduction of pioneer species by creating new niches . For example, beavers may flood an area, allowing new species to immigrate. [ 16 ]
The concept of ecologic succession also applies to underwater habitats. If a space becomes newly available in a reef surrounding, haplosclerid and calcareous sponges are the first animals to initially occur in this environment in greater numbers than other species. These types of sponges grow faster and have a shorter life-span than the species which follow them in this habitat. [ 17 ]
Following ecological disturbances caused by humans, such as post-industrial areas where there may be high amounts of toxic waste, certain pioneer species such as those that can withstand heavy metals will begin to grow. Vascular plants tend to draw in contaminants from the soil through their roots, so often the first plants to colonize such an environment are lichens and bryophytes (mosses, liverworts , and hornworts ) because they do not have true roots. [ 18 ]
Due to harsh impacts from grazing livestock in certain areas, soils may be degraded by erosion, resulting in shallow soils. In restoration efforts, certain pioneer species are used which can withstand poor growing conditions. Black locust ( Robinia pseudoacacia ) is often used to restore post-grazing pastures, because it can grow in eroded environments and has nitrogen-fixing abilities, which add nutrients to the soil and improve the chance of success for other plant species. Over time, black locust adds organic matter and increases the depth of soil, which helps other species of plants reestablish. [ 19 ]
The term pioneer species is also used to refer to the first species, usually plants, to return to an area after disturbance as part of the process of secondary succession . Disturbances may include floods, tornadoes , forest fires , deforestation , or clearing by other means. [ 20 ]
Pioneer species tend to be fast-growing, shade-intolerant, and tend to reproduce large numbers of offspring quickly. The seeds of pioneer species can sometimes remain viable for years or decades in the soil seed bank and often are triggered to sprout by disturbance. [ 21 ] Mycorrhizal fungi have a powerful influence on the growth of pioneer species. [ 22 ]
Some examples of the plants in such areas include: [ citation needed ] | https://en.wikipedia.org/wiki/Pioneer_species |
Pioneers in Engineering ( PiE ) is a student-run organization that promotes the study of science, technology, engineering, and mathematics, collectively known as STEM fields . The organization was established in 2008 as a non-profit corporation by University of California, Berkeley student, Xiao-Yu Fu. The University provides training and mentorship opportunities for local high school students to improve their technological skills, by participating in a robotics competition , during which each student team designs, builds, and programs functional robots. [ 1 ] [ 2 ] [ 3 ] Since 2008, over 20 schools have participated in the program.
Pioneers in Engineering was founded in 2008 by University of California, Berkeley student and Tau Beta Pi member, Xiao-Yu Fu. The organization's office is in UC Berkeley's O'Brien Hall. Staff members, including University of California undergraduates and graduates, design and assemble robotics starter kits for the competition, develop mentors for the program, plan and manufacture the annual competition field, and oversee public relations and internal communications. [ 4 ] As of 2013 [update] , the organization has expanded to include 107 staff members. [ citation needed ]
In preparation for the annual competition, robotic kits are distributed to groups of high schools students, who are paired with undergraduate mentors who assist the teams during the competition. A final tournament is held at the end of the season, allowing the student teams to reveal their work, for which awards are presented. [ 5 ] | https://en.wikipedia.org/wiki/Pioneers_in_Engineering |
The Pioneers of Underwater Acoustics Medal is awarded by the Acoustical Society of America in recognition of "an outstanding contribution to the science of underwater acoustics , as evidenced by publication of research results in professional journals or by other accomplishments in the field". The award was named in honor of H. J. W. Fay , Reginald Fessenden , Harvey Hayes , G. W. Pierce , and Paul Langevin . [ 1 ] | https://en.wikipedia.org/wiki/Pioneers_of_Underwater_Acoustics_Medal |
Piophila is a genus of small flies which includes the species known as the cheese fly . Both Piophila species feed on carrion , including human corpses . [ 1 ] [ 2 ]
Piophila are small dark flies with unmarked wings. The setulae (fine hairs) on the thorax are confined to three distinct rows. [ 3 ]
There are two species in the genus Piophila : [ 4 ]
This article related to members of the muscomorph flies superfamily Tephritoidea is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Piophila |
Piotr Piecuch (born January 21, 1960) is a Polish-born American physical chemist . He holds the title of university distinguished professor [ 1 ] [ 2 ] in the department of chemistry at Michigan State University , East Lansing, Michigan , United States . He supervises a group, [ 3 ] whose research focuses on theoretical and computational chemistry as well as theoretical and computational physics , particularly on the development and applications of many-body methods for accurate quantum calculations for molecular systems and atomic nuclei , including methods based on coupled cluster theory, mathematical methods of chemistry and physics , and theory of intermolecular forces . His group is also responsible for the development of the coupled-cluster computer codes incorporated in the widely used GAMESS (US) package.
Piecuch studied chemistry at the undergraduate and graduate levels at the University of Wrocław , Poland . He received his M.S. degree in 1983 and Ph.D. degree in 1988. After postdoctoral and research faculty appointments at the University of Waterloo , Canada (1988–91, 1994–95), where he worked with Professors Josef Paldus and Jiri Čížek , University of Arizona (1992–93), where he worked with Professor Ludwik Adamowicz , University of Toronto , Canada (1995–97), where he worked with the recipient of the 1986 Nobel Prize in Chemistry , [ 4 ] Professor John C. Polanyi , and University of Florida (1997–98), where he worked with Professor Rodney J. Bartlett , he joined the faculty at Michigan State University as an assistant professor in 1998. He was promoted to an associate professor in 2002 and professor in 2004. He was named a university distinguished professor in 2007. While his primary appointment at Michigan State University is with the department of chemistry, he has also held adjunct professorship appointments in the Department of Physics and Astronomy (2003–10, 2014-). During his tenure at Michigan State University, he was named a visiting professor at the University of Coimbra , Portugal (2006), Kyoto University , Japan (2005), Institute for Molecular Science , National Institutes of Natural Sciences , in Okazaki, Japan (2012–13), [ 5 ] [ 6 ] and a Clark Way Harrison Distinguished Visiting Professor at the Washington University in St. Louis , United States (2016). [ 7 ] The latter visit resulted in the creation of the on-line lecture series on algebraic and diagrammatic methods for many-fermion systems, consisting of more than 40 high-definition videos, [ 8 ] available on YouTube .
Piecuch has established himself as one of the leaders of electronic structure theory . Of particular note are his contributions to coupled-cluster and many-body theories. His work on the renormalized and active-space coupled-cluster methods is especially important, since the resulting approximations, such as CR-CC(2,3), CCSDt, or CC(t;3), and their extensions utilizing the equation-of-motion coupled-cluster concepts, for example, CR-EOMCC, EOMCCSDt, etc., can accurately describe potential energy surfaces , biradicals , and electronic excitations in molecules without resorting to complex multi-reference wave functions .
In general, Piecuch has been among the early and lead developers of multi-reference , response, extended, generalized, and externally corrected coupled-cluster methods, including approximate coupled-pair approaches for strongly correlated systems. His group and collaborators have also implemented linear scaling, local correlation coupled-cluster methods for large systems. The resulting multi-level local schemes that combine higher-level methods, such as CR-CC(2,3), to treat reactive parts of large molecular systems, with lower-order local or canonical methods, such as MP2 or CCSD, to describe chemically inactive regions are particularly valuable.
Although the exponential wave function ansatz of coupled-cluster theory was originally proposed by nuclear physicists, it initially found limited applications in nuclear structure theory . Piecuch and his associates, and their co-workers working in the area of nuclear theory have demonstrated the great utility of quantum-chemistry -inspired coupled-cluster approximations in the field of nuclear physics .
In addition to his coupled-cluster work, Piecuch has made major contributions to fundamental understanding and formal description of intermolecular forces, particularly pairwise non-additive effects, and developed potential energy surface extrapolation schemes based on scaling correlation energies. He has applied theoretical methods to solve many important problems in chemistry and physics. This is exemplified in papers by his group and collaborators on spectroscopy , reaction dynamics , ro-vibrational resonances in van der Waals complexes , several important reaction mechanisms in organic and bioinorganic chemistry, catalysis , and photochemistry .
As of July 6, 2018, his research has resulted in more than 200 publications [ 9 ] that according to the Web of Science have received more than 10,100 citations and the h-index of 56. [ 10 ] On July 6, 2018, Google Scholar reported more than 11,500 citations and the h-index of 61. [ 11 ] In particular, Piecuch's original contributions to coupled-cluster theory, as applied to molecular problems, have been extensively discussed in the scientific literature. [ 12 ] [ 13 ] [ 14 ] [ 15 ] His intermolecular forces theory effort has been reviewed by several authors as well. [ 16 ] [ 17 ] His nuclear coupled-cluster theory research, in addition to being cited in the scientific literature, has received attention in more popular publications. [ 18 ] [ 19 ] [ 20 ] [ 21 ] [ 22 ] As of July 6, 2018, he has given 235 invited lectures at national and international symposia, and academic and research institutions in the United States, Australia, Brazil, Canada, Chile, China, Czech Republic, France, Germany, Greece, Hungary, India, Italy, Japan, New Zealand, Poland, Portugal, Russia, Slovakia, South Africa, Spain, Sweden, Switzerland, Tunisia, and United Kingdom. [ 23 ] He has co-edited 6 books and 2 special journal issues, and served on many scientific committees and advisory boards, including the editorial boards of several scientific journals and book series. [ 24 ]
Piecuch is an elected member of the International Academy of Quantum Molecular Science (2018), [ 25 ] an elected Fellow of the Royal Society of Chemistry (2016), [ 26 ] [ 27 ] an elected Distinguished Fellow of the Kosciuszko Foundation Collegium of Eminent Scientists (2015), [ 28 ] [ 29 ] [ 30 ] an elected Fellow of the American Association for the Advancement of Science (2011), [ 31 ] [ 32 ] [ 33 ] an elected Fellow of the American Physical Society (2008), [ 34 ] [ 35 ] [ 36 ] an Elected Member of the European Academy of Sciences, Arts and Humanities [ 37 ] in Paris, France (2003), and a recipient of a number of other awards and honors, including, in addition to the title of the university distinguished professor that he received in 2007, the Lawrence J. Schaad Lectureship in Theoretical Chemistry at Vanderbilt University (2017), [ 38 ] [ 39 ] the S.R. Palit Memorial Lecture at the Indian Association for the Cultivation of Science ( Kolkata , India, 2007), [ 40 ] [ 41 ] the Invitation Fellowship of the Japan Society for the Promotion of Science (2005), the QSCP [ 42 ] Promising Scientist Prize of Centre de Mécanique Ondulatoire Appliquée, France, for "Scientific and Human Endeavour and Achievement" (2004), [ 43 ] the Alfred P. Sloan Research Fellowship (2002–2004), [ 44 ] [ 45 ] the Wiley – International Journal of Quantum Chemistry Young Investigator Award (2000), [ 46 ] three awards from the Polish Chemical Society for Research (1983, 1986, 1992), the award from the Minister of National Education of Poland (1989), and two awards from the Polish Academy of Sciences (1982).
Piecuch was born in Wrocław, Poland to Telesfor and Hanna Piecuch, and has one sister, Katarzyna. He is married to Jolanta Piecuch (maiden name Sanetra). They have one child, Anna Piecuch. | https://en.wikipedia.org/wiki/Piotr_Piecuch |
Pips are small but easily countable items, such as the dots on dominoes and dice , or the symbols on a playing card that denote its suit and value.
In playing cards , pips are small symbols on the front side of the cards that determine the suit of the card and its rank. For example, a standard 52-card deck consists of four suits of thirteen cards each: spades, hearts, clubs, and diamonds. Each suit contains three face cards – the jack, queen, and king. The remaining ten cards are called pip cards and are numbered from one to ten. (The "one" is almost always changed to " ace " and often is the highest card in many games, followed by the face cards.) Each pip card consists of an encoding in the top left-hand corner (and, because the card is also inverted upon itself, the lower right-hand corner) which tells the card-holder the value of the card. In Europe, it is more common to have corner indices on all four corners which lets left-handed players fan their cards more comfortably. The center of the card contains pips representing the suit. The number of pips corresponds with the number of the card, and the arrangement of the pips is generally the same from deck to deck.
Pip cards are also known as numerals or numeral cards .
In point-trick games where cards often score their value in pips (or equivalent if they are court cards e.g. a King may be worth 13), card points are sometimes referred to as pips.
Many French-suited packs derived from the English pattern contain a variation on the pip style for the Ace of spades , often consisting of an especially large pip or even a representative image, along with information about the deck's manufacturer, originally to display the stamp duty . This is also the case for the Ace of clubs in the Paris pattern and the Ace of diamonds in the Russian pattern . For German-suited playing cards , the deuce of hearts was used for this purpose, and for Latin-suited playing cards , the ace of coins was used.
Historically German pips are generally different from the pips used in France and England, and the latter dates from at least the fourteenth century CE. [ 1 ]
On dice , pips are small dots on each face of a die. These pips are typically arranged in patterns denoting the numbers one through n , where n is the number of faces. For the common six-sided die, the sum of the pips on opposing faces traditionally adds up to seven.
Pips are commonly colored black on white or yellow dice, and white on dice of other colors, although colored pips on white/yellow dice are not uncommon; Asian dice often have an enlarged red single pip for the "one" face, while the dice for the 1964 commercial game Kismet feature black pips for 1 and 6, red pips for 2 and 5, and green pips for 3 and 4.
Dominoes use pips that are similar to dice. Each half of a domino tile can have anywhere from no pips all the way up to 18, in practice, depending on the set. A common double-six set has pips all the way up to six arranged in the same manner to dice pips. The game is generally played by up to four players only, individually or in partners (pairs). Domino sets having more pips on one half of the tile allow the game to be played by more players. | https://en.wikipedia.org/wiki/Pip_(counting) |
A pipe-in-pipe system [ 1 ] is a form of plumbing where all water pipes are running inside another pipe. Its purpose is to ensure that any leaks in the innermost pipe will not leak into the building structure and can be detected, as well as make for easier change of any internal pipes with leakage without opening the walls.
A pipe-in-pipe system consists of four main components: an inner pipe, an outer pipe, wall boxes, and a distribution cabinet. [ 2 ]
In Norway, domestic plumbing based on pipe-in-pipe systems (known as: rør-i-rør system ) was introduced in 1995, and has since become a legal requirement in all new houses being built. Due to experience with water damages with many traditional copper pipes in Norway between 1970 and 1995, new requirements came in 1997 stating that water pipes should be easily accessible for replacement after installation. [ 3 ] These requirements have since lead to the current de facto requirement for pipe-in-pipe plumbing.
During normal operation, the water flows through the inner water pipe, which is enclosed by the outer goods pipe. The plumbing leads back to a centrally located distribution cabinet where the pipes to all tapping points of the home are gathered in one place. In the event of any damage and leakage to the internal pipes, the external pipes must ensure that the water leak is safely diverted to the distribution cabinet where it is made visible for inspection before it is lead to a room with drains in the floor. It can be advantageous to install a water leak sensor and connect it to an automatic water stop valve which closes the water supply. In the event of visible leaks, there must also be an easily accessible manual main shut-off valve which must stop water supply to all pipes. [ 4 ]
Due to the way pipe-in-pipe systems are installed using flexible internal and external pipes, it is possible to pull out and replace the water pipes without having to open up walls. To ensure this, it is important that the outer pipes are clamped properly and securely so that they remain attached to the building structure, while also not being damaged. This is an absolutely crucial factor for how easy it is to change the water pipes, and the clamping rings used should be attached near wall boxes and distribution cabinets.
In addition to proper clamping of the external pipes to the building structure, proper clamping of the distributors inside the distribution cabinet is also important to avoid water hammers when taps are closed rapidly. Pipe-in-pipe systems may be more susceptible or vulnerable to water hammers, [ citation needed ] and are therefore recommended to be used together with soft closing water taps. | https://en.wikipedia.org/wiki/Pipe-in-pipe_system |
A pipe is a tubular section or hollow cylinder , usually but not necessarily of circular cross-section , used mainly to convey substances which can flow — liquids and gases ( fluids ), slurries , powders and masses of small solids. It can also be used for structural applications; a hollow pipe is far stiffer per unit weight than the solid members.
In common usage the words pipe and tube are usually interchangeable, but in industry and engineering, the terms are uniquely defined. Depending on the applicable standard to which it is manufactured, pipe is generally specified by a nominal diameter with a constant outside diameter (OD) and a schedule that defines the thickness. Tube is most often specified by the OD and wall thickness, but may be specified by any two of OD, inside diameter (ID), and wall thickness. Pipe is generally manufactured to one of several international and national industrial standards. [ 1 ] While similar standards exist for specific industry application tubing, tube is often made to custom sizes and a broader range of diameters and tolerances. Many industrial and government standards exist for the production of pipe and tubing. The term "tube" is also commonly applied to non-cylindrical sections, i.e., square or rectangular tubing. In general, "pipe" is the more common term in most of the world, whereas "tube" is more widely used in the United States.
Both "pipe" and "tube" imply a level of rigidity and permanence, whereas a hose (or hosepipe) is usually portable and flexible. Pipe assemblies are almost always constructed with the use of fittings such as elbows, tees, and so on, while tube may be formed or bent into custom configurations. For materials that are inflexible, cannot be formed, or where construction is governed by codes or standards, tube assemblies are also constructed with the use of tube fittings.
Additionally, pipes are used for many purposes that do not involve conveying fluid. Handrails , scaffolding, and support structures are often constructed from structural pipes, especially in an industrial environment.
The first known use of pipes was in Ancient Egypt . The Pyramid of Sahure , completed around the 25th century BC, included a temple with an elaborate drainage system including more than 380 m (1,247 ft) of copper piping. [ 2 ]
During the Napoleonic Wars Birmingham gunmakers tried to use rolling mills to make iron musket barrels. [ 3 ] One of them, Henry Osborne, developed a relatively effective process in 1817 with which he started to make iron gas tubes ca. 1820, selling some to gas lighting pioneer Samuel Clegg . [ 4 ]
When steel pipes were introduced in 19th century, they initially were riveted, and later clamped with H-shaped bars (even though methods for making weldless steel tubes were known already in the 1870s [ 5 ] ), until by the early 1930s these methods were replaced by welding , which is still widely used today. [ 6 ]
There are three processes for metallic pipe manufacture. Centrifugal casting of hot alloyed metal is one of the most prominent process. [ citation needed ] Ductile iron pipes are generally manufactured in such a fashion.
Seamless pipe (SMLS) is formed by drawing a solid billet over a piercing rod to create the hollow shell in a process called rotary piercing . As the manufacturing process does not include any welding, seamless pipes are perceived to be stronger and more reliable. Historically, seamless pipe was regarded as withstanding pressure better than other types, and was often more available than welded pipe.
Advances since the 1970s, in materials, process control, and non-destructive testing, allow correctly specified welded pipe to replace seamless in many applications. Welded pipe is formed by rolling plate and welding the seam (usually by Electric resistance welding ("ERW"), or Electric Fusion Welding ("EFW")). The weld flash can be removed from both inner and outer surfaces using a scarfing blade. The weld zone can also be heat-treated to make the seam less visible. Welded pipe often has tighter dimensional tolerances than the seamless type, and can be cheaper to manufacture.
There are a number of processes that may be used to produce ERW pipes. Each of these processes leads to coalescence or merging of steel components into pipes. Electric current is passed through the surfaces that have to be welded together; as the components being welded together resist the electric current, heat is generated which forms the weld. Pools of molten metal are formed where the two surfaces are connected as a strong electric current is passed through the metal; these pools of molten metal form the weld that binds the two abutted components.
ERW pipes are manufactured from the longitudinal welding of steel. The welding process for ERW pipes is continuous, as opposed to welding of distinct sections at intervals. ERW process uses steel coil as feedstock.
The High Frequency Induction Technology (HFI) welding process is used for manufacturing ERW pipes. In this process, the current to weld the pipe is applied by means of an induction coil around the tube. HFI is generally considered to be technically superior to "ordinary" ERW when manufacturing pipes for critical applications, such as for usage in the energy sector, in addition to other uses in line pipe applications, as well as for casing and tubing.
Large-diameter pipe (25 centimetres (10 in) or greater) may be ERW, EFW, or Submerged Arc Welded ("SAW") pipe. There are two technologies that can be used to manufacture steel pipes of sizes larger than the steel pipes that can be produced by seamless and ERW processes. The two types of pipes produced through these technologies are longitudinal-submerged arc-welded (LSAW) and spiral-submerged arc-welded (SSAW) pipes. LSAW are made by bending and welding wide steel plates and most commonly used in oil and gas industry applications. Due to their high cost, LSAW pipes are seldom used in lower value non-energy applications such as water pipelines. SSAW pipes are produced by spiral (helicoidal) welding of steel coil and have a cost advantage over LSAW pipes, as the process uses coils rather than steel plates. As such, in applications where spiral-weld is acceptable, SSAW pipes may be preferred over LSAW pipes. Both LSAW pipes and SSAW pipes compete against ERW pipes and seamless pipes in the diameter ranges of 16”-24”.
Tubing for flow, either metal or plastic, is generally extruded .
Pipe is made out of many types of material including ceramic , glass , fiberglass , many metals , concrete and plastic . In the past, wood and lead ( Latin plumbum , from which comes the word ' plumbing ') were commonly used.
Typically metallic piping is made of steel or iron, such as unfinished, black (lacquer) steel, carbon steel , stainless steel , galvanized steel , brass , and ductile iron . Iron based piping is subject to corrosion if used within a highly oxygenated water stream. [ 7 ] Aluminum pipe or tubing may be utilized where iron is incompatible with the service fluid or where weight is a concern; aluminum is also used for heat transfer tubing such as in refrigerant systems. Copper tubing is popular for domestic water (potable) plumbing systems; copper may be used where heat transfer is desirable (i.e. radiators or heat exchangers). Inconel , chrome moly , and titanium steel alloys are used in high temperature and pressure piping in process and power facilities. When specifying alloys for new processes, the known issues of creep and sensitization effect must be taken into account.
Lead piping is still found in old domestic and other water distribution systems , but is no longer permitted for new potable water piping installations due to its toxicity . Many building codes now require that lead piping in residential or institutional installations be replaced with non-toxic piping or that the tubes' interiors be treated with phosphoric acid . According to a senior researcher and lead expert with the Canadian Environmental Law Association , "[...] there is no safe level of lead [for human exposure]". [ 8 ] In 1991 the US EPA issued the Lead and Copper Rule , a federal regulation which limits the concentration of lead and copper allowed in public drinking water, as well as the permissible amount of pipe corrosion occurring due to the water itself. In the US it is estimated that 6.5 million lead service lines (pipes that connect water mains to home plumbing) installed before the 1930s are still in use. [ 9 ]
Plastic tubing is widely used for its light weight, chemical resistance, non-corrosive properties, and ease of making connections. Plastic materials include polyvinyl chloride (PVC), [ 10 ] chlorinated polyvinyl chloride (CPVC), fibre reinforced plastic (FRP), [ 11 ] reinforced polymer mortar (RPMP), [ 11 ] polypropylene (PP), polyethylene (PE), cross-linked high-density polyethylene (PEX), polybutylene (PB), and acrylonitrile butadiene styrene (ABS), for example. In many countries, PVC pipes account for most pipe materials used in buried municipal applications for drinking water distribution and wastewater mains. [ 10 ]
Pipe may be made from concrete or ceramic , usually for low-pressure applications such as gravity flow or drainage. Pipes for sewage are still predominantly made from concrete or vitrified clay . Reinforced concrete can be used for large-diameter concrete pipes. This pipe material can be used in many types of construction, and is often used in the gravity-flow transport of storm water. Usually such pipe will have a receiving bell or a stepped fitting, with various sealing methods applied at installation.
When the alloys for piping are forged, metallurgical tests are performed to determine material composition by % of each chemical element in the piping, and the results are recorded in a material test report, also known as a Mill Test Report (MTR). [ 12 ] These tests can be used to prove that the alloy conforms to various specifications (e.g. 316 SS ). The tests are stamped by the mill's QA/QC department and can be used to trace the material back to the mill by future users, such as piping and fitting manufacturers. Maintaining the traceability between the alloy material and associated MTR is an important quality assurance issue. QA often requires the heat number to be written on the pipe. Precautions must also be taken to prevent the introduction of counterfeit materials. As a backup to etching/labeling of the material identification on the pipe, positive material identification (PMI) is performed using a handheld device; the device scans the pipe material using an emitted electromagnetic wave ( x-ray fluorescence/XRF ) and receives a reply that is spectrographically analyzed.
Pipe sizes can be confusing because the terminology may relate to historical dimensions. For example, a half-inch iron pipe does not have any dimension that is a half inch. Initially, a half inch pipe did have an inner diameter of 1 ⁄ 2 inch (13 mm)—but it also had thick walls. As technology improved, thinner walls became possible, but the outside diameter stayed the same so it could mate with existing older pipe, increasing the inner diameter beyond half an inch. The history of copper pipe is similar. In the 1930s, the pipe was designated by its internal diameter and a 1 ⁄ 16 -inch (1.6 mm) wall thickness. Consequently, a 1-inch (25 mm) copper pipe had a 1 + 1 ⁄ 8 -inch (28.58 mm) outside diameter. The outside diameter was the important dimension for mating with fittings. The wall thickness on modern copper is usually thinner than 1 ⁄ 16 -inch (1.6 mm), so the internal diameter is only "nominal" rather than a controlling dimension. [ 13 ] Newer pipe technologies sometimes adopted a sizing system as its own. PVC pipe uses the Nominal Pipe Size .
Pipe sizes are specified by a number of national and international standards, including API 5L, ANSI / ASME B36.10M and B36.19M in the US, BS 1600 and BS EN 10255 in the United Kingdom and Europe.
There are two common methods for designating pipe outside diameter (OD). The North American method is called Nominal Pipe Size (NPS) and is based on inches (also frequently referred to as NB ("Nominal Bore")). The European version is called DN ("Diametre Nominal" / "Nominal Diameter") and is based on millimetres. Designating the outside diameter allows pipes of the same size to be fit together no matter what the wall thickness.
Since the outside diameter is fixed for a given pipe size, the inside diameter will vary depending on the wall thickness of the pipe. For example, 2" Schedule 80 pipe has thicker walls and therefore a smaller inside diameter than 2" Schedule 40 pipe.
Steel pipe has been produced for about 150 years. The pipe sizes that are in use today in PVC and galvanized were originally designed years ago for steel pipe. The number system, like Sch 40, 80, 160, were set long ago and seem a little odd. For example, Sch 20 pipe is even thinner than Sch 40, but same OD. And while these pipes are based on old steel pipe sizes, there is other pipe, like cpvc for heated water, that uses pipe sizes, inside and out, based on old copper pipe size standards instead of steel.
Many different standards exist for pipe sizes, and their prevalence varies depending on industry and geographical area. The pipe size designation generally includes two numbers; one that indicates the outside (OD) or nominal diameter, and the other that indicates the wall thickness. In the early twentieth century, American pipe was sized by inside diameter. This practice was abandoned to improve compatibility with pipe fittings that must usually fit the OD of the pipe, but it has had a lasting impact on modern standards around the world.
In North America and the UK, pressure piping is usually specified by Nominal Pipe Size (NPS) and schedule (SCH). Pipe sizes are documented by a number of standards, including API 5L, ANSI / ASME B36.10M (Table 1) in the US, and BS 1600 and BS 1387 in the United Kingdom. Typically the pipe wall thickness is the controlled variable, and the Inside Diameter (I.D.) is allowed to vary. The pipe wall thickness has a variance of approximately 12.5 percent.
In the rest of Europe pressure piping uses the same pipe IDs and wall thicknesses as Nominal Pipe Size, but labels them with a metric Diameter Nominal (DN) instead of the imperial NPS. For NPS larger than 14, the DN is equal to the NPS multiplied by 25. (Not 25.4) This is documented by EN 10255 (formerly DIN 2448 and BS 1387) and ISO 65:1981, and it is often called DIN or ISO pipe.
Japan has its own set of standard pipe sizes, often called JIS pipe.
The Iron Pipe Size (IPS) is an older system still used by some manufacturers and legacy drawings and equipment. The IPS number is the same as the NPS number, but the schedules were limited to Standard Wall (STD), Extra Strong (XS), and Double Extra Strong (XXS). STD is identical to SCH 40 for NPS 1/8 to NPS 10, inclusive, and indicates .375" wall thickness for NPS 12 and larger. XS is identical to SCH 80 for NPS 1/8 to NPS 8, inclusive, and indicates .500" wall thickness for NPS 8 and larger. Different definitions exist for XXS, however it is never the same as SCH 160. XXS is in fact thicker than SCH 160 for NPS 1/8" to 6" inclusive, whereas SCH 160 is thicker than XXS for NPS 8" and larger.
Another old system is the Ductile Iron Pipe Size (DIPS), which generally has larger ODs than IPS.
Copper plumbing tube for residential plumbing follows an entirely different size system in America, often called Copper Tube Size (CTS); see domestic water system . Its nominal size is neither the inside nor outside diameter. Plastic tubing, such as PVC and CPVC, for plumbing applications also has different sizing standards [ vague ] .
Agricultural applications use PIP sizes, which stands for Plastic Irrigation Pipe . PIP comes in pressure ratings of 22 psi (150 kPa), 50 psi (340 kPa), 80 psi (550 kPa), 100 psi (690 kPa), and 125 psi (860 kPa) and is generally available in diameters of 6, 8, 10, 12, 15, 18, 21, and 24 inches (15, 20, 25, 30, 38, 46, 53, and 61 cm).
The manufacture and installation of pressure piping is tightly regulated by the ASME "B31" code series such as B31.1 or B31.3 which have their basis in the ASME Boiler and Pressure Vessel Code (BPVC) . This code has the force of law in Canada and the US. Europe and the rest of the world has an equivalent system of codes. Pressure piping is generally pipe that must carry pressures greater than 10 to 25 atmospheres, although definitions vary. To ensure safe operation of the system, the manufacture, storage, welding, testing, etc. of pressure piping must meet stringent quality standards.
Manufacturing standards for pipes commonly require a test of chemical composition and a series of mechanical strength tests for each heat of pipe. A heat of pipe is all forged from the same cast ingot, and therefore had the same chemical composition. Mechanical tests may be associated to a lot of pipe, which would be all from the same heat and have been through the same heat treatment processes. The manufacturer performs these tests and reports the composition in a mill traceability report and the mechanical tests in a material test report , both of which are referred to by the acronym MTR. Material with these associated test reports is called traceable . For critical applications, third party verification of these tests may be required; in this case an independent lab will produce a certified material test report (CMTR), and the material will be called certified .
Some widely used pipe standards or piping classes are:
API 5L was changed in the second half of 2008 to edition 44 from edition 43 to make it identical to ISO 3183. It is important to note that the change has created the requirement that sour service, ERW pipe, pass a hydrogen induced cracking (HIC) test per NACE TM0284 in order to be used for sour service.
Pipe installation is often more expensive than the material and a variety of specialized tools, techniques, and parts have been developed to assist this. Pipe is usually delivered to a customer or jobsite as either "sticks" or lengths of pipe (typically 20 feet (6.1 m), called single random length) or they are prefabricated with elbows, tees and valves into a prefabricated pipe spool [A pipe spool is a piece of pre-assembled pipe and fittings, usually prepared in a shop so that installation on the construction site can be more efficient.]. Typically, pipe smaller than 2 inches (5.1 cm) are not pre-fabricated. The pipe spools are usually tagged with a bar code and the ends are capped (plastic) for protection. The pipe and pipe spools are delivered to a warehouse on a large commercial/industrial job and they may be held indoors or in a gridded laydown yard. The pipe or pipe spool is retrieved, staged, rigged, and then lifted into place. On large process jobs the lift is made using cranes and hoist and other material lifts. They are typically temporarily supported in the steel structure using beam clamps, straps, and small hoists until the pipe supports are attached or otherwise secured.
An example of a tool used for installation for a small plumbing pipe (threaded ends) is the pipe wrench . Small pipe is typically not heavy and can be lifted into place by the installation craft laborer. However, during a plant outage or shutdown, the small (small bore) pipe may also be pre-fabricated to expedite installation during the outage. After the pipe is installed it will be tested for leaks. Before testing it may need to be cleaned by blowing air or steam or flushing with a liquid.
Pipes are usually either supported from below or hung from above (but may also be supported from the side), using devices called pipe supports. Supports may be as simple as a pipe "shoe" which is akin to a half of an I-beam welded to the bottom of the pipe; they may be "hung" using a clevis , or with trapeze type of devices called pipe hangers. Pipe supports of any kind may incorporate springs, snubbers, dampers, or combinations of these devices to compensate for thermal expansion , or to provide vibration isolation, shock control, or reduced vibration excitation of the pipe due to earthquake motion. Some dampers are simply fluid dashpots, but other dampers may be active hydraulic devices that have sophisticated systems that act to dampen peak displacements due to externally imposed vibrations or mechanical shocks. The undesired motions may be process derived (such as in a fluidized bed reactor) or from a natural phenomenon such as an earthquake (design basis event or DBE).
Pipe hanger assembles are usually attached with pipe clamps. Possible exposure to high temperatures and heavy loads should be included when specifying which clamps are needed. [ 14 ]
Pipes are commonly joined by welding , using threaded pipe and fittings; sealing the connection with a pipe thread compound, Polytetrafluoroethylene (PTFE) Thread seal tape , oakum , or PTFE string, or by using a mechanical coupling. Process piping is usually joined by welding using a TIG or MIG process. The most common process pipe joint is the butt weld. The ends of pipe to be welded must have a certain weld preparation called an End Weld Prep (EWP) which is typically at an angle of 37.5 degrees to accommodate the filler weld metal. The most common pipe thread in North America is the National Pipe Thread (NPT) or the Dryseal (NPTF) version. Other pipe threads include the British Standard Pipe Thread (BSPT), the garden hose thread (GHT), and the fire hose coupling (NST).
Copper pipes are typically joined by soldering , brazing , compression fittings , flaring , or crimping . Plastic pipes may be joined by solvent welding , heat fusion , or elastomeric sealing.
If frequent disconnection will be required, gasketed pipe flanges or union fittings provide better reliability than threads. Some thin-walled pipes of ductile material, such as the smaller copper or flexible plastic water pipes found in homes for ice makers and humidifiers, for example, may be joined with compression fittings .
Underground pipe typically uses a "push-on" gasket style of pipe that compresses a gasket into a space formed between the two adjoining pieces. Push-on joints are available on most types of pipe. A pipe joint lubricant must be used in the assembly of the pipe. Under buried conditions, gasket-joint pipes allow for lateral movement due to soil shifting as well as expansion/contraction due to temperature differentials. [ 15 ] Plastic MDPE and HDPE gas and water pipes are also often joined with Electrofusion fittings.
Large above ground pipe typically uses a flanged joint, which is generally available in ductile iron pipe and some others. It is a gasket style where the flanges of the adjoining pipes are bolted together, compressing the gasket into a space between the pipe.
Mechanical grooved couplings or Victaulic joints are also frequently used for frequent disassembly and assembly. Developed in the 1920s, these mechanical grooved couplings can operate up to 120 pounds per square inch (830 kPa) working pressures and available in materials to match the pipe grade. Another type of mechanical coupling is a flareless tube fitting (Major brands include Swagelok, Ham-Let, Parker); this type of compression fitting is typically used on small tubing under 2 inches (51 mm) in diameter.
When pipes join in chambers where other components are needed for the management of the network (such as valves or gauges), dismantling joints are generally used, in order to make mounting/dismounting easier.
Fittings are also used to split or join a number of pipes together, and for other purposes. A broad variety of standardized pipe fittings are available; they are generally broken down into either a tee, an elbow, a branch, a reducer/enlarger, or a wye. Valves control fluid flow and regulate pressure. The piping and plumbing fittings and valves articles discuss them further.
The inside of pipes can be cleaned with a tube cleaning process , if they are contaminated with debris or fouling . This depends on the process that the pipe will be used for and the cleanliness needed for the process. In some cases the pipes are cleaned using a displacement device formally known as a Pipeline Inspection Gauge or "pig"; alternately the pipes or tubes may be chemically flushed using specialized solutions that are pumped through. In some cases, where care has been taken in the manufacture, storage, and installation of pipe and tubing, the lines are blown clean with compressed air or nitrogen.
Pipe is widely used in the fabrication of handrails, guardrails, and railings.
Steel pipe (or black iron pipe) was once the most popular choice for supply of water and flammable gases. Steel pipe is still used in many homes and businesses to convey natural gas or propane fuel, and is a popular choice in fire sprinkler systems due to its high heat resistance. In commercial buildings, steel pipe is used to convey heating or cooling water to heat exchangers , air handlers, variable air volume (VAV) devices, or other HVAC equipment.
Steel pipe is sometimes joined using threaded connections, where tapered threads (see National Pipe Thread ) are cut into the end of the tubing segment, sealant is applied in the form of thread sealing compound or thread seal tape (also known as PTFE or Teflon tape), and it is then threaded into a corresponding threaded fitting using two pipe wrenches . Beyond domestic or light commercial settings, steel pipe is often joined by welding , or by use of mechanical couplings made by companies such as Victaulic or Anvil International (formerly Grinnell) that hold the pipe joint together via a groove pressed or cut (a rarely used older practice), into the ends of the pipes.
Other variations of steel pipe include various stainless steel and chrome alloys. In high-pressure situations these are usually joined by TIG welding.
In Canada, with respect to natural gas (NG) and propane (LP gas), black iron pipe (BIP) is commonly used to connect an appliance to the supply. It must however be marked (either painted yellow or yellow banding attached at certain intervals) and certain restrictions apply to which nominal pipe size (NPS) can be put through walls and buildings. With propane in particular, BIP can be run from an exterior tank (or cylinder) provided it is well protected from the weather, and an anode -type of protection from corrosion is in place when the pipe is to be installed underground.
Copper tubing is most often used for supply of hot and cold water, and as refrigerant line in HVAC systems. There are two basic types of copper tubing, soft copper and rigid copper. Copper tubing is joined using flare connection, compression connection, or solder. Copper offers a high level of resistance to corrosion, but is becoming very costly.
Soft (or ductile) copper tubing can be bent easily to travel around obstacles in the path of the tubing. While the work hardening of the drawing process used to size the tubing makes the copper hard/rigid, it is carefully annealed to make it soft again; it is therefore more expensive to produce than non-annealed, rigid copper tubing. It can be joined by any of the three methods used for rigid copper, and it is the only type of copper tubing suitable for flare connections. Soft copper is the most popular choice for refrigerant lines in split-system air conditioners and heat pumps.
Flare connections require that the end of a tubing section be spread outward in a bell shape using a flare tool . A flare nut then compresses this bell-shaped end onto a male fitting. Flare connections are a labor-intensive method of making connections, but are quite reliable over the course of many years.
Rigid copper is a popular choice for water lines. It is joined using a sweat, compression or crimped/pressed connection. Rigid copper, rigid due to the work hardening of the drawing process, cannot be bent and must use elbow fittings to go around corners or around obstacles. If heated and allowed to slowly cool, called annealing , then rigid copper will become soft and can be bent/formed without cracking.
Solder fittings are smooth, and easily slip onto the end of a tubing section. Both the male and female ends of the pipe or pipe connectors are cleaned thoroughly then coated with flux to make sure there is no surface oxide and to ensure that the solder will bond properly with the base metal. The joint is then heated using a torch , and solder is melted into the connection. When the solder cools, it forms a very strong bond which can last for decades. Solder-connected rigid copper is the most popular choice for water supply lines in modern buildings. In situations where many connections must be made at once (such as plumbing of a new building), solder offers much quicker and much less expensive joinery than compression or flare fittings. The term sweating is sometimes used to describe the process of soldering pipes.
Compression fittings use a soft metal or thermoplastic ring (the compression ring or "ferrule") which is squeezed onto the pipe and into the fitting by a compression nut. The soft metal conforms to the surface of the tubing and the fitting, and creates a seal. Compression connections do not typically have the long life that sweat connections offer, but are advantageous in many cases because they are easy to make using basic tools. A disadvantage in compression connections is that they take longer to make than sweat, and sometimes require retightening over time to stop leaks.
Crimped or pressed connections use special copper fittings which are permanently attached to rigid copper tubing with a powered crimper. The special fittings, manufactured with sealant already inside, slide over the tubing to be connected. Thousands of pounds-force per square inch of pressure are used to deform the fitting and compress the sealant against the inner copper tubing, creating a watertight seal. Advantages of this method are:
Disadvantages are:
Aluminium is sometimes used due to its low cost, resistance to corrosion and solvents, and its ductility. Aluminium tube is more desirable than steel for the conveyance of flammable solvents, since it cannot create sparks when manipulated. Aluminium tubing can be connected by flare or compression fittings, or it can be welded by the TIG or heliarc processes.
Tempered glass pipes are used for specialized applications, such as corrosive liquids, medical or laboratory wastes, or pharmaceutical manufacturing. Connections are generally made using specialized gasket or O-ring fittings.
Plastic pipes used in manufacturing.
Plastic pipe fittings include PVC pipe fittings, PP / PPH pipe fitting mould, PE pipe and ABS pipe fitting. | https://en.wikipedia.org/wiki/Pipe_(fluid_conveyance) |
Pipe cutting or pipe profiling is a mechanized industrial process that removes material from pipe or tubing to create a desired profile. Typical profiles include straight cuts, mitres, saddles and midsection holes. These complex cuts are usually required to allow a tight fit between two parts that are to be joined via arc welding .
Pipe cutting is used in industries such as offshore operations, pipe processing, shipbuilding and pressure vessel manufacture. This technology is valued for its ability to produce the intricate cuts and profiles often required in these fields. Common applications include pipework, offshore jackets, steel frameworks, cranes, and demolition of structures offshore.
Hot cutting refers to a process in which materials are cut using a thermal torch. One of the most common techniques is oxy-fuel gas cutting, which is used extensively for cutting carbon and low-alloy steels. However, its efficiency diminishes as the alloy content of the material increases, limiting its applicability for high-alloy steels. Arc-based cutting methods are used for cutting these materials. Among these, plasma arc cutting is the most commonly employed technique, owing to its precision and ability to cut through high-alloy steels efficiently. [ 1 ] Thermal cutting creates a shallow region contaminated material adjacent to the cut surfaces - the heat affected zone . For some applications it is necessary to remove this material by mechanical means, such as grinding or machining, prior to use or further fabrication by welding. [ 2 ]
The cutting torch can be integrated into a machine to perform precision cutting operations. In multi-axis machines, the movement of the axes is powered by electric motors and synchronized to guide the torch and the pipe being cut along a programmed path, resulting in the desired cutting profile. The synchronization of axes is accomplished either mechanically, via cams , levers and gears, or electronically with microprocessors , which is computer numerical control (CNC).
Where the high temperatures and sources of ignition required by hot cutting are not desirable, air- or hydraulically-powered pipe cutting machines are used. These comprise a clamshell or chain-mounted cutting head holding a tool steel and feed mechanism which advances the tool a set amount per revolution round the pipe. Tools may be styled to cut and/or prepare the bevel for welding in a single or multiple passes.
High pressure abrasive water jets can be used for cold cutting. This technology is employed for the decommissioning of offshore structures. [ citation needed ] | https://en.wikipedia.org/wiki/Pipe_Cutting |
Pipe bursting is a trenchless method of replacing buried pipelines (such as sewer, water, or natural gas pipes) without the need for a traditional construction trench . "Launching and receiving pits" replace the trench needed by conventional pipe-laying.
HDPE pipe is the common replacement pipe. [ 1 ] [ 2 ]
There are five key pieces of equipment used in a pipebursting operation: the expander head, pulling rods, a pulling machine, a retaining device, and a hydraulic power pack .
Today's expander heads have a leading end much smaller in diameter than the trailing (bursting) end, small enough to fit through the pipe that will be replaced. The smaller leading end is designed to guide the expander head through the existing pipe; earlier models did not have this feature and lost course at times, resulting in incomplete pipe bursts and project failures.
The transition from the leading end to the trailing end can include "fins" that make first contact with the existing pipe. Using these fins as the primary breaking point is a very effective way to ensure that the pipe is broken along the entire circumference.
A machine is set in the receiving pit to pull the expander head and new pipe into the line. The head is pulled by heavy, interlocking links that form a chain. Each link weighs several hundred pounds.
All of the equipment used in a pipe bursting operation is powered by one or multiple hydraulic power generators.
Pipe bursting may also be used to expand pipeline carrying capacity by replacing smaller pipes with larger ones, or "upsizing." Extensive proving work by the gas and water industries has demonstrated the feasibility of upsizing gas mains, water mains and sewers . Upsizing from 100mm to 225mm diameter is now well established, and pipes of up to 36 inch [ 3 ] diameter and greater have been replaced. | https://en.wikipedia.org/wiki/Pipe_bursting |
Pipe drift is a measure of the roundness or eccentricity of the inside wall of a pipe. "API drift" refers to primary specifications set forth in API Specification 5CT ( ISO 11960), "Specification for Casing and Tubing". "Alternate drift" refers to alternate drift specifications listed in API 5CT. "Special drift" refers to industry drift specifications other than those found in API 5CT.
Drifting means measuring a pipe's inner roundness. Drifting is typically performed by passing a cylindrical mandrel through the length of the pipe to detect occlusions. It occurs both at the pipe mill and in the field. Drifting is performed to ensure that tools, pumps, smaller pipe, and other items can be passed through the pipe.
This article related to natural gas, petroleum or the petroleum industry is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pipe_drift |
In fluid mechanics , pipe flow is a type of fluid flow within a closed conduit , such as a pipe , duct or tube . It is also called as Internal flow . [ 1 ] The other type of flow within a conduit is open channel flow . These two types of flow are similar in many ways, but differ in one important aspect. Pipe flow does not have a free surface which is found in open-channel flow. Pipe flow, being confined within closed conduit, does not exert direct atmospheric pressure , but does exert hydraulic pressure on the conduit.
Not all flow within a closed conduit is considered pipe flow. Storm sewers are closed conduits but usually maintain a free surface and therefore are considered open-channel flow. The exception to this is when a storm sewer operates at full capacity, and then can become pipe flow.
Energy in pipe flow is expressed as head and is defined by the Bernoulli equation . In order to conceptualize head along the course of flow within a pipe, diagrams often contain a hydraulic grade line (HGL). Pipe flow is subject to frictional losses as defined by the Darcy-Weisbach formula .
The behavior of pipe flow is governed mainly by the effects of viscosity and gravity relative to the inertial forces of the flow. Depending on the effect of viscosity relative to inertia, as represented by the Reynolds number , the flow can be either laminar or turbulent . For circular pipes of different surface roughness, at a Reynolds number below the critical value of approximately 2000 [ 2 ] pipe flow will ultimately be laminar, whereas above the critical value turbulent flow can persist, as shown in Moody chart . For non-circular pipes, such as rectangular ducts, the critical Reynolds number is shifted, but still ∼ O ( 10 3 ) {\displaystyle \sim {\mathcal {O}}(10^{3})} depending on the aspect ratio. [ 3 ] Earlier transition to turbulence, happening at Reynolds number one order of magnitude smaller, i.e. ∼ O ( 10 2 ) {\displaystyle \sim {\mathcal {O}}(10^{2})} , [ 4 ] can happen in channels with special geometrical shapes, such as the Tesla valve .
Flow through pipes can roughly be divided into two: | https://en.wikipedia.org/wiki/Pipe_flow |
In the process industry , chemical industry , manufacturing industry , and other commercial and industrial contexts, pipe marking is used to identify the contents, properties and flow direction of fluids in piping. It is typically carried out by marking piping through labels and color codes. Pipe marking helps personnel and fire response teams identify the correct pipes for operational, maintenance or emergency response purposes.
Pipes are used extensively in commercial and industrial buildings and on industrial plant (e.g. oil refineries ) to transfer fluids between items of plant and equipment. [ 1 ] Positive identification assists operations personnel to correctly identify plant when carrying out routine or maintenance activities, and for emergency personnel when responding to emergencies. Pipe marking is particularly important for identification where pipes run along pipe racks , through walls and bulkheads and through floors. [ 2 ]
A range of corporate, national and international codes, standards and regulations are in use around the world.
In the United States , Occupational Safety and Health Administration regulations recommend following American Society of Mechanical Engineers Standard A13.1-2015 - Scheme for the Identification of Piping Systems . [ 3 ]
The standard states that labels should be placed where easily viewed by a person standing near the pipe at any of the following points: [ 4 ]
2015 revisions added oxidizing materials to the existing 'Flammables' classification. The other major change allowed and encouraged labels to incorporate the GHS signal word, hazard pictograms , and hazard statements . This addition helped identify additional dangers when dealing with materials that fit into multiple categories, like hydrogen sulfide , which is both flammable and toxic. [ 4 ]
In 2014, the International Institute of Ammonia Refrigeration introduced a specialized label design for use when marking pipes associated with refrigeration systems using ammonia , including information such as the physical state , pressure and purpose in the system. [ 6 ]
The National Fire Protection Association have a special labeling system in the standard for Health Care Facilities, such as hospitals and dentistry offices. This standard puts more emphasis on gases found in Medical gas supply systems , which consist of both oxidizing gases and gases that displace oxygen . [ 7 ]
In the United Kingdom there are three principal regulations that mandate the marking of equipment and piping:
The regulations require that vessels containing hazardous substances together with the pipes containing or transporting such substances must be labelled or marked with the relevant hazard pictograms or pipe marking. The labels used on pipes must be positioned visibly in the vicinity of the most hazardous points, such as valves and joints; at both sides of bulkheads and floor penetrations; and at reasonable intervals.
The regulations do not specify a specific marking system, but BS EN ISO 1710 Graphical symbols — Safety colours and safety signs is often used.
A widely used British Standard (BS) for marking equipment is:
The Standard stipulates the colours to be used. These are as follows: [ 2 ]
In addition to the basic colours, certain safety colours are used:
The arrangement of markings is for the safety colour to be between bands of the basic colour. [ 2 ]
Firewater service would be:
The pipe contents must be identified adjacent to the banding. [ 2 ] This can be done by giving either:
The direction of flow should also be identified near the banding. [ 2 ]
Examples using this system are as shown.
The Indian Standard IS 2379 provides for a ground colour and a coloured band on piping to identify material. [ 11 ]
Colour bands of 25 mm to 100 mm width are placed at locations such as battery limits, intersections, near valves, at walls, starting and terminating points. There is a large range of bands which define the contents of the line. For example, for oils.
Pipes, ducts and conduits are identification by the Australian Standard AS 1345—1995 “Identification of the contents of pipes, conduits and ducts” [ 12 ]
Ships and marine facilities must conform to an international standard for piping systems identification. This is ISO 14726:2008 Ships and marine technology — Identification colours for the content of piping systems . [ 13 ]
This is a two-colour banded marking system. The main colour shows what the fluid is being used for. This is on either side of the secondary colour which indicates what the substance actually is. The main colours are as follows: [ 13 ]
International Standard ISO 20560-1:2020 Safety information for the content of piping systems and tanks — Part 1: Piping systems was intended to replace the variety of regulations and standards across countries and regions. Basic identification colours and warning symbols identify the pipe contents and any hazards. [ 14 ]
Pipe markers consists of 4 basic elements:
Colours and substances are typically as follows: [ 14 ]
International Standard ISO 20560-2 Safety information for the content of piping systems and tanks — Part 2: Tanks, provides a similar colour scheme for tanks.
RAL colour standard charts are used by architects, construction industry and road safety. [ 15 ]
The pipe identification colours are as shown in the table. | https://en.wikipedia.org/wiki/Pipe_marking |
In fluid dynamics , pipe network analysis is the analysis of the fluid flow through a hydraulics network, containing several or many interconnected branches. The aim is to determine the flow rates and pressure drops in the individual sections of the network. This is a common problem in hydraulic design.
To direct water to many users, municipal water supplies often route it through a water supply network . A major part of this network will consist of interconnected pipes. This network creates a special class of problems in hydraulic design, with solution methods typically referred to as pipe network analysis . Water utilities generally make use of specialized software to automatically solve these problems. However, many such problems can also be addressed with simpler methods, like a spreadsheet equipped with a solver, or a modern graphing calculator.
Once the friction factors of the pipes are obtained (or calculated from pipe friction laws such as the Darcy-Weisbach equation ), we can consider how to calculate the flow rates and head losses on the network. Generally the head losses (potential differences) at each node are neglected, and a solution is sought for the steady-state flows on the network, taking into account the pipe specifications (lengths and diameters), pipe friction properties and known flow rates or head losses.
The steady-state flows on the network must satisfy two conditions:
If there are sufficient known flow rates, so that the system of equations given by (1) and (2) above is closed (number of unknowns = number of equations), then a deterministic solution can be obtained.
The classical approach for solving these networks is to use the Hardy Cross method . In this formulation, first you go through and create guess values for the flows in the network. The flows are expressed via the volumetric flow rates Q. The initial guesses for the Q values must satisfy the Kirchhoff laws (1). That is, if Q7 enters a junction and Q6 and Q4 leave the same junction, then the initial guess must satisfy Q7 = Q6 + Q4. After the initial guess is made, then, a loop is considered so that we can evaluate our second condition. Given a starting node, we work our way around the loop in a clockwise fashion, as illustrated by Loop 1. We add up the head losses according to the Darcy–Weisbach equation for each pipe if Q is in the same direction as our loop like Q1, and subtract the head loss if the flow is in the reverse direction, like Q4. In other words, we add the head losses around the loop in the direction of the loop; depending on whether the flow is with or against the loop, some pipes will have head losses and some will have head gains (negative losses).
To satisfy the Kirchhoff's second laws (2), we should end up with 0 about each loop at the steady-state solution. If the actual sum of our head loss is not equal to 0, then we will adjust all the flows in the loop by an amount given by the following formula, where a positive adjustment is in the clockwise direction.
where
The clockwise specifier (c) means only the flows that are moving clockwise in our loop, while the counter-clockwise specifier (cc) is only the flows that are moving counter-clockwise.
This adjustment doesn't solve the problem, since most networks have several loops. It is okay to use this adjustment, however, because the flow changes won't alter condition 1, and therefore, the other loops still satisfy condition 1. However, we should use the results from the first loop before we progress to other loops.
An adaptation of this method is needed to account for water reservoirs attached to the network, which are joined in pairs by the use of 'pseudo-loops' in the Hardy Cross scheme. This is discussed further on the Hardy Cross method site.
The modern method is simply to create a set of conditions from the above Kirchhoff laws (junctions and head-loss criteria). Then, use a Root-finding algorithm to find Q values that satisfy all the equations. The literal friction loss equations use a term called Q 2 , but we want to preserve any changes in direction. Create a separate equation for each loop where the head losses are added up, but instead of squaring Q , use | Q |· Q instead (with | Q | the absolute value of Q ) for the formulation so that any sign changes reflect appropriately in the resulting head-loss calculation.
In many situations, especially for real water distribution networks in cities (which can extend between thousands to millions of nodes), the number of known variables (flow rates and/or head losses) required to obtain a deterministic solution will be very large. Many of these variables will not be known, or will involve considerable uncertainty in their specification. Furthermore, in many pipe networks, there may be considerable variability in the flows, which can be described by fluctuations about mean flow rates in each pipe. The above deterministic methods are unable to account for these uncertainties, whether due to lack of knowledge or flow variability.
For these reasons, a probabilistic method for pipe network analysis has recently been developed, [ 1 ] based on the maximum entropy method of Jaynes. [ 2 ] In this method, a continuous relative entropy function is defined over the unknown parameters. This entropy is then maximized subject to the constraints on the system, including Kirchhoff's laws, pipe friction properties and any specified mean flow rates or head losses, to give a probabilistic statement ( probability density function ) which describes the system. This can be used to calculate mean values (expectations) of the flow rates, head losses or any other variables of interest in the pipe network. This analysis has been extended using a reduced-parameter entropic formulation, which ensures consistency of the analysis regardless of the graphical representation of the network. [ 3 ] A comparison of Bayesian and maximum entropy probabilistic formulations for the analysis of pipe flow networks has also been presented, showing that under certain assumptions (Gaussian priors), the two approaches lead to equivalent predictions of mean flow rates. [ 4 ]
Other methods of stochastic optimization of water distribution systems rely on metaheuristic algorithms, such as simulated annealing [ 5 ] and genetic algorithms . [ 6 ] | https://en.wikipedia.org/wiki/Pipe_network_analysis |
Structural steel pipe racks typically support pipes , power cables and instrument cable trays in petrochemical , chemical and power plants . Occasionally, pipe racks may also support mechanical equipment, vessels and valve access platforms. Main pipe racks generally transfer material between equipment and storage or utility areas. Storage racks found in warehouses are not pipe racks, even if they store lengths of pipe. [ 1 ]
A pipe rack is the main artery of a process unit. Pipe racks carry process and utility piping and may also include instrument and cable trays as well as equipment mounted over all of these. [ 2 ]
Pipe racks consist of a series of transverse beams that run along the length of the pipe system, spaced at uniform intervals typically around 20 ft. To allow maintenance access under the pipe rack, the transverse beams are typically moment frames. Transverse beams are typically connected with longitudinal struts. [ 1 ]
There are different types of pipes on the pipe rack. Utility pipes which include steam , cooling water, extinguishing water, fuel oil , and so on. These pipes are mostly located in the middle of a one-level pipe rack or on the top level when there are two levels. Then there are the process pipes. These pipes carry product that is part of the chemical reaction itself. These are placed on the outside of the utility pipes (especially if they are heavy) or on the bottom level when there are multiple levels. Lastly, relief and flare pipes which fulfill a safety goal. They protect the installation against too much pressure and are always located on the outside of the rack. [ 3 ]
This article related to natural gas, petroleum or the petroleum industry is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pipe_rack |
A pipe wrench is any of several types of wrench that are designed to turn threaded pipe and pipe fittings for assembly (tightening) or disassembly (loosening). The Stillson wrench , or Stillson-pattern wrench , is the usual form of pipe wrench, especially in the US. The Stillson name is that of the original patent holder, who licensed the design to a number of manufacturers; the patent has since expired. A different type of wrench with compound leverage often used on pipes, the plumber wrench , is also called a "pipe wrench" in some places.
The Stillson wrench is an adjustable wrench (spanner) with hardened serrated teeth on its jaws. The hard teeth bite into the softer metal of the round pipe and provide the grip needed to turn a pipe, even against fair resistance. The design of the adjustable jaw, which permits a certain amount of intentional play out of square , allows it to bind on the pipe, with forward pressure on the handle pulling the jaws tighter. On some models, two leaf springs , above and below the knurled adjusting knob, help unlock the jaw when pressure on the handle of the wrench is released.
Pipe wrenches are not intended for regular use on hex nuts or other fittings. However, if a hex nut becomes rounded (stripped) so that it cannot be moved by standard wrenches, a pipe wrench can be used to free the bolt or nut, because the pipe wrench is designed to bite into rounded metal surfaces.
Pipe wrenches are classified by the length of the handle. They are generally available in sizes from 6 inches (150 mm) to 48 inches (1,200 mm) or larger. They are usually made of forged steel . Today, aluminium might be substituted to reduce the weight of the body of the wrench, although the teeth and jaw remain steel. Teeth and jaw kits (which also contain adjustment rings and springs) can be bought to repair broken wrenches.
Daniel C. Stillson (1826–1899), a mechanic at the Walworth Company, in Cambridge, Massachusetts , created the first such wrench. [ 1 ] On October 12, 1869, US patent #95,744 was issued to Stillson. [ 2 ]
On 17 August 1888, the Swedish inventor Johan Petter Johansson (1853–1943) took out his first patent on the adjustable pipe wrench . [ 3 ] The Swedish Patent Office issued the patent again in 1894. [ 4 ] The idea emerged after he established his company Enköpings Mekaniska Verkstad . Back then, nut dimensions were poorly standardized, so each time a tradesman was out on a job, he needed a trolley to take a set of fixed pipe wrenches with him. Johansson's tool could grip nuts of different dimensions. [ 5 ]
In South Africa , the terms "bobbejaan spanner" and "baboon spanner" are commonly used, [ 6 ] especially for large pipe wrenches. Bobbejaan is the Afrikaans term for a baboon .
In Spain and Morocco , they are called grifa .
In Mexico they are known and called "stillson" without even using the word llave ("wrench").
In Turkey they are known as "English Keys". | https://en.wikipedia.org/wiki/Pipe_wrench |
Pipecolic acid (piperidine-2-carboxylic acid) is an organic compound with the formula HNC 5 H 9 CO 2 H. It is a carboxylic acid derivative of piperidine and, as such, an amino acid , although not one encoded genetically. Like many other α - amino acids , pipecolic acid is chiral, although the S-stereoisomer is more common. It is a colorless solid.
Its biosynthesis starts from lysine . [ 1 ] CRYM , a taxon-specific protein that also binds thyroid hormones , is involved in the pipecolic acid pathway.
It accumulates in pipecolic acidemia . Elevation of pipecolic acid can be associated with some forms of epilepsy , such as pyridoxine-dependent epilepsy . [ 2 ] [ 3 ]
Like most amino acids, pipecolic acid is a chelating agent. One complex is Cu(HNC 5 H 9 CO 2 ) 2 (H 2 O) 2 . [ 4 ]
Pipecolic acid was identified in the Murchison meteorite . [ 5 ] It also occurs in the leaves of the genus Myroxylon , a tree from South America. [ 6 ]
This biochemistry article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pipecolic_acid |
A pipefitter or steamfitter [ 1 ] is a tradesman who installs, assembles, fabricates, maintains, and repairs mechanical piping systems. Pipefitters usually begin as helpers or apprentices. Journeyman pipefitters deal with industrial/commercial/marine piping and heating/cooling systems. Typical industrial process pipe is under high pressure, which requires metals such as carbon steel , stainless steel , and many different alloy metals fused together through precise cutting, threading, grooving, bending, and welding . A plumber concentrates on lower pressure piping systems for sewage and potable tap water in the industrial, commercial, institutional, or residential atmosphere. Utility piping typically consists of copper, PVC , CPVC , polyethylene , and galvanized pipe , which is typically glued, soldered , or threaded . Other types of piping systems include steam, ventilation, hydraulics, chemicals, fuel, and oil. [ 2 ]
In Canada, pipefitting is classified as a compulsory trade , and carries a voluntary "red seal" inter-provincial standards endorsement . Pipefitter apprenticeships are controlled and regulated provincially, and in some cases allow for advance standing in similar trades upon completion.
In the United States, many states require pipefitters to be licensed. Requirements differ from state to state, but most include a four- to five-year apprenticeship. Union pipefitters are required to pass an apprenticeship test (often called a "turn-out exam") before becoming a licensed journeyman. Others can be certified by NCCER (formerly the National Center for Construction Education and Research).
Pipefitters install, assemble, fabricate, maintain, repair, and troubleshoot pipe carrying fuel, chemicals, water, steam, and air in heating, cooling, lubricating, and various other process piping systems. Pipefitters are employed in the maintenance departments of power stations, refineries, offshore installations, factories, and similar establishments, by pipefitting contractors. [ 3 ]
In North America , union pipefitters are members of the United Association . Wages vary from area to area, based on demands for experienced personnel and existing contracts between local unions and contractors. The United Association is also affiliated with the piping trades unions in Ireland and Australia .
Pipefitters should not be confused with pipelayers . Both trades involve pipe and valves and both use some of the same tools. [ 4 ] However, pipelayers usually work outside, laying pipe underground or on the seabed, whereas pipefitters typically work inside, installing piping in buildings, aeroplanes, or ships. [ 4 ]
One author summarizes the different tasks as follows: [ 4 ]
Pipe layers operate the backhoes and trenching machinery that dig the trenches to accommodate the placement of sanitary sewer pipes and stormwater sewer drainpipes. They use surveyor’s equipment to ensure the trenches have the proper slope and install the pieces of pipe in the trenches, joining the ends with cement, glue, or welding equipment. Using an always-open or always-closed valve called a tap, pipe layers connect them to a wider system and bury the pipes.
whereas,
Pipe fitters plan and test piping and tubing layouts; cut, bend or fabricate pipe or tubing segments; and join those segments by threading them, using lead joints, welding, brazing, cementing, or soldering them together. They install manual, pneumatic, hydraulic and electric valves in pipes to control the flow through the pipes or tubes. These workers create the system of tubes in boilers and make holes in walls and bulkheads to accommodate the passage of the pipes they install.
Pipe fitters are often exposed to hazardous or dangerous materials, such as asbestos , lead , ammonia , steam , flammable gases, various resins and solvents including benzene and various refrigerants . Much progress was made in the 20th century toward eliminating or reducing hazardous materials exposures. Many aspects of hazardous materials are now regulated by law in most countries, including asbestos usage and removal and refrigerant selection and handling. [ 5 ] A major occupational hazard that pipefitters face is from welding fumes, including ultraviolet light, heavy metals, and chlorinated compounds during welding or torch cutting. Contact with previously mentioned solvents, adhesives, and epoxies during repair or installation of PVC/ABS pipes. Exposure to materials and liquids in old pipes during repair or removal. [ 6 ]
Other occupational hazards include exposure to the weather, heavy lifting, crushing hazards, lacerations, and other risks normal to the construction industry. | https://en.wikipedia.org/wiki/Pipefitter |
In hydrology , pipeflow is a type of subterranean water flow where water travels along cracks in the soil or old root systems found in above ground vegetation .
In such soils which have a high vegetation content water is able to travel along the 'pipes', allowing water to travel faster than throughflow . Here, water can move at speeds between 50 and 500 m/h.
This hydrology article is a stub . You can help Wikipedia by expanding it .
This ecology -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pipeflow |
A pipelayer or sideboom [ citation needed ] is a type of a construction vehicle used to lay pipes. It is used in the construction of oil, gas and water pipelines .
The lifting equipment of pipelayers includes:
A pipelayer can also be equipped with accessories:
Construction, installation, operation, inspection, testing, and maintenance of sidebooms are covered by OSHA standard 1926.1440 - Sideboom cranes [ 1 ] and ASME B30.14 - Side Boom Tractors. [ 2 ]
This vehicle-related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pipelayer_(vehicle) |
A pipeline is a system of pipes for long-distance transportation of a liquid or gas, typically to a market area for consumption. The latest data from 2014 gives a total of slightly less than 2,175,000 miles (3,500,000 km) of pipeline in 120 countries around the world. [ 1 ] The United States had 65%, Russia had 8%, and Canada had 3%, thus 76% of all pipeline were in these three countries. [ 1 ] The main attribute to pollution from pipelines is caused by corrosion and leakage. [ 2 ]
Pipeline and Gas Journal ' s worldwide survey figures indicate that 118,623 miles (190,905 km) of pipelines are planned and under construction. Of these, 88,976 miles (143,193 km) represent projects in the planning and design phase; 29,647 miles (47,712 km) reflect pipelines in various stages of construction. Liquids and gases are transported in pipelines, and any chemically stable substance can be sent through a pipeline. [ 3 ]
Pipelines exist for the transport of crude and refined petroleum, fuels – such as oil, natural gas and biofuels – and other fluids including sewage , slurry , water , beer , hot water or steam for shorter distances and even pneumatic systems which allow for the generation of suction pressure for useful work and in transporting solid objects. [ 4 ] Pipelines are useful for transporting water for drinking or irrigation over long distances when it needs to move over hills , or where canals or channels are poor choices due to considerations of evaporation , pollution , or environmental impact.
Oil pipelines are made from steel or plastic tubes which are usually buried. The oil is moved through the pipelines by pump stations along the pipeline. Natural gas (and similar gaseous fuels) are pressurized into liquids known as natural gas liquids (NGLs). [ 5 ] Natural gas pipelines are constructed of carbon steel . Hydrogen pipeline transport is the transportation of hydrogen through a pipe. Pipelines are one of the safest ways of transporting materials as compared to road or rail, and hence in war, pipelines are often the target of military attacks. [ 6 ]
The first crude oil pipeline was built by the Oil Transport Association, which constructed a 2-inch (51 mm) wrought iron pipeline over a 6-mile (9.7 km) track from an oil field in Pennsylvania to a railroad station in Oil Creek , in the 1860s. Some of the first major submarine pipelines were constructed across the English Channel in 1944 during Operation Pluto . These provided an estimated 8 per cent of all petroleum products used by the Allies on the Western Front between the Normandy landings and the end of Second World War.
Pipelines are generally the most economical way to transport large quantities of oil, refined oil products or natural gas over land. For example, in 2014, pipeline transport of crude oil cost about $5 per barrel, while rail transport cost about $10 to $15 per barrel. [ 7 ] Trucking has even higher costs due to the additional labor required; employment on completed pipelines represents only "1% of that of the trucking industry.". [ 8 ]
In the United States, 70% of crude oil and petroleum products are shipped by pipeline. (23% are by ship, 4% by truck, and 3% by rail) In Canada for natural gas and petroleum products, 97% are shipped by pipeline. [ 7 ]
Natural gas (and similar gaseous fuels) are lightly pressurized into liquids known as Natural Gas Liquids (NGLs). Small NGL processing facilities can be located in oil fields so the butane and propane liquid under light pressure of 125 pounds per square inch (860 kPa), can be shipped by rail, truck or pipeline. Propane can be used as a fuel in oil fields to heat various facilities used by the oil drillers or equipment and trucks used in the oil patch. EG: Propane will convert from a gas to a liquid under light pressure, 100 psi, give or take depending on temperature, and is pumped into cars and trucks at less than 125 psi (860 kPa) at retail stations. Pipelines and rail cars use about double that pressure to pump at 250 psi (1,700 kPa).
The distance to ship propane to markets is much shorter, as thousands of natural-gas processing plants are located in or near oil fields. Many Bakken Basin oil companies in North Dakota, Montana, Manitoba and Saskatchewan gas fields separate the NGLs in the field, allowing the drillers to sell propane directly to small wholesalers, eliminating the large refinery control of product and prices for propane or butane.
The most recent major pipeline to start operating in North America is a TransCanada natural gas line going north across the Niagara region bridges. This gas line carries Marcellus shale gas from Pennsylvania and other tied in methane or natural gas sources into the Canadian province of Ontario. It began operations in the fall of 2012, supplying 16 percent of all the natural gas used in Ontario. [ citation needed ]
This new US-supplied natural gas displaces the natural gas formerly shipped to Ontario from western Canada in Alberta and Manitoba, thus dropping the government regulated pipeline shipping charges because of the significantly shorter distance from gas source to consumer. To avoid delays and US government regulation, many small, medium and large oil producers in North Dakota have decided to run an oil pipeline north to Canada to meet up with a Canadian oil pipeline shipping oil from west to east. This allows the Bakken Basin and Three Forks oil producers to get higher negotiated prices for their oil because they will not be restricted to just one wholesale market in the US. The distance from the biggest oil patch in North Dakota, in Williston, North Dakota , is only about 85 miles or 137 kilometers to the Canada–US border and Manitoba . Mutual funds and joint ventures are the largest investors in new oil and gas pipelines. In the fall of 2012, the US began exporting propane to Europe, known as LPG, as wholesale prices there are much higher than in North America. Additionally, a pipeline is currently being constructed from North Dakota to Illinois, commonly known as the Dakota Access Pipeline . [ 9 ]
As more North American pipelines are built, even more exports of LNG, propane, butane, and other natural gas products occur on all three US coasts. To give insight, North Dakota Bakken region's oil production has grown by 600% from 2007 to 2015. [ 10 ] North Dakota oil companies are shipping huge amounts of oil by tanker rail car as they can direct the oil to the market that gives the best price, and rail cars can be used to avoid a congested oil pipeline to get the oil to a different pipeline in order to get the oil to market faster or to a different less busy oil refinery. However, pipelines provide a cheaper means to transport by volume.
Enbridge in Canada is applying to reverse an oil pipeline going from east-to-west (Line 9) and expanding it and using it to ship western Canadian bitumen oil eastward. [ 11 ] From a presently rated 250,000 barrels equivalent per day pipeline, it will be expanded to between 1.0 and 1.3 million barrels per day. It will bring western oil to refineries in Ontario, Michigan, Ohio, Pennsylvania, Quebec and New York by early 2014. New Brunswick will also refine some of this western Canadian crude and export some crude and refined oil to Europe from its deep water oil ULCC loading port.
Although pipelines can be built under the sea, that process is economically and technically demanding, so the majority of oil at sea is transported by tanker ships . Similarly, it is often more economically feasible to transport natural gas in the form of LNG, however the break-even point between LNG and pipelines would depend on the volume of natural gas and the distance it travels. [ 12 ]
The market size for oil and gas pipeline construction experienced tremendous growth prior to the economic downturn in 2008. After faltering in 2009, demand for pipeline expansion and updating increased the following year as energy production grew. [ 13 ] By 2012, almost 32,000 miles (51500 km) of North American pipeline were being planned or under construction. [ 14 ] When pipelines are constrained, additional pipeline product transportation options may include the use of drag reducing agents, or by transporting product via truck or rail.
Oil pipelines are made from steel or plastic tubes with inner diameter typically from 4 to 48 inches (100 to 1,220 mm). Most pipelines are typically buried at a depth of about 3 to 6 feet (0.91 to 1.83 m). To protect pipes from impact , abrasion , and corrosion , a variety of methods are used. These can include wood lagging (wood slats), concrete coating, rockshield, high-density polyethylene , imported sand padding, sacrificial cathodes and padding machines. [ 15 ]
Crude oil contains varying amounts of paraffin wax and in colder climates wax buildup may occur within a pipeline. Often these pipelines are inspected and cleaned using pigging , the practice of using devices known as "pigs" to perform various maintenance operations on a pipeline. The devices are also known as "scrapers" or "Go-devils". "Smart pigs" (also known as "intelligent" or "intelligence" pigs) are used to detect anomalies in the pipe such as dents, metal loss caused by corrosion, cracking or other mechanical damage. [ 16 ] These devices are launched from pig-launcher stations and travel through the pipeline to be received at any other station down-stream, either cleaning wax deposits and material that may have accumulated inside the line or inspecting and recording the condition of the line.
For natural gas, pipelines are constructed of carbon steel and vary in size from 2 to 60 inches (51 to 1,524 mm) in diameter, depending on the type of pipeline. The gas is pressurized by compressor stations and is odorless unless mixed with a mercaptan odorant where required by a regulating authority.
Until damaged during the Russian invasion of Ukraine , [ 17 ] the Russian – Ukrainian Transammiak line was the longest ammonia pipeline in the world, at 2,500 km. [ 18 ] It connected the TogliattiAzot facility in Russia to the exporting Black Sea -port of Odesa in Ukraine.
Pipelines have been used for transportation of ethanol in Brazil, and there are several ethanol pipeline projects in Brazil and the United States. [ 19 ] The main problems related to the transport of ethanol by pipeline are its corrosive nature and tendency to absorb water and impurities in pipelines, which are not problems with oil and natural gas. [ 19 ] [ 20 ] Insufficient volumes and cost-effectiveness are other considerations limiting construction of ethanol pipelines. [ 20 ] [ 21 ]
In the US minimal amounts of ethanol are transported by pipeline. Most ethanol is shipped by rail, the main alternatives being truck and barge. Delivering ethanol by pipeline is the most desirable option, but ethanol's affinity for water and solvent properties require the use of a dedicated pipeline, or significant cleanup of existing pipelines.
Slurry pipelines are sometimes used to transport coal or ore from mines. The material to be transported is closely mixed with water before being introduced to the pipeline; at the far end, the material must be dried. One example is a 525-kilometre (326 mi) slurry pipeline which is planned to transport iron ore from the Minas-Rio mine (producing 26.5 million tonnes per year) to the Port of Açu in Brazil. [ 22 ] An existing example is the 85-kilometre (53 mi) Savage River Slurry pipeline in Tasmania , Australia, possibly the world's first when it was built in 1967. It includes a 366-metre (1,201 ft) bridge span at 167 metres (548 ft) above the Savage River. [ 23 ] [ 24 ]
Hydrogen pipeline transport is a transportation of hydrogen through a pipe as part of the hydrogen infrastructure . Hydrogen pipeline transport is used to connect the point of hydrogen production or delivery of hydrogen with the point of demand, with transport costs similar to CNG , [ 25 ] the technology is proven. [ 26 ] Most hydrogen is produced at the place of demand with every 50 to 100 miles (160 km) an industrial production facility. [ 27 ] The 1938 Rhine-Ruhr 240-kilometre (150 mi) hydrogen pipeline is still in operation. [ 28 ] As of 2004 [update] , there are 900 miles (1,400 km) of low pressure hydrogen pipelines in the US and 930 miles (1,500 km) in Europe.
Two millennia ago, the ancient Romans made use of large aqueducts to transport water from higher elevations by building the aqueducts in graduated segments that allowed gravity to push the water along until it reached its destination. Hundreds of these were built throughout Europe and elsewhere, and along with flour mills were considered the lifeline of the Roman Empire. The ancient Chinese also made use of channels and pipe systems for public works. The famous Han dynasty court eunuch Zhang Rang (d. 189 AD) once ordered the engineer Bi Lan to construct a series of square-pallet chain pumps outside the capital city of Luoyang . [ 29 ] These chain pumps serviced the imperial palaces and living quarters of the capital city as the water lifted by the chain pumps was brought in by a stoneware pipe system. [ 29 ] [ 30 ]
Pipelines are useful for transporting water for drinking or irrigation over long distances when it needs to move over hills , or where canals or channels are poor choices due to considerations of evaporation , pollution , or environmental impact.
The 530 km (330 miles) Goldfields Water Supply Scheme in Western Australia using 750 mm (30 inch) pipe and completed in 1903 was the largest water supply scheme of its time. [ 31 ] [ 32 ]
Examples of significant water pipelines in South Australia are the Morgan-Whyalla pipeline (completed 1944) and Mannum-Adelaide pipeline (completed 1955) pipelines, both part of the larger Snowy Mountains scheme . [ 33 ]
Two Los Angeles, California aqueducts, the Owens Valley aqueduct (completed 1913) and the Second Los Angeles Aqueduct (completed 1970), include extensive use of pipelines.
The Great Manmade River of Libya supplies 3,680,000 cubic metres (4,810,000 cu yd) of water each day to Tripoli, Benghazi, Sirte, and several other cities in Libya. The pipeline is over 2,800 kilometres (1,700 mi) long, and is connected to wells tapping an aquifer over 500 metres (1,600 ft) underground. [ 34 ]
District heating or teleheating systems consist of a network of insulated feed and return pipes which transport heated water, pressurized hot water , or sometimes steam to the customer. While steam is hottest and may be used in industrial processes due to its higher temperature, it is less efficient to produce and transport due to greater heat losses. Heat transfer oils are generally not used for economic and ecological reasons. The typical annual loss of thermal energy through distribution is around 10%, as seen in Norway's district heating network. [ 36 ]
District heating pipelines are normally installed underground, with some exceptions. Within the system, heat storage may be installed to even out peak load demands. Heat is transferred into the central heating of the dwellings through heat exchangers at heat substations , without mixing of the fluids in either system.
Bars in the Veltins-Arena , a major football ground in Gelsenkirchen , Germany, are interconnected by a 5-kilometre (3.1 mi) long beer pipeline. In Randers city in Denmark, the so-called Thor Beer pipeline was operated. Originally, copper pipes ran directly from the brewery, but when the brewery moved out of the city in the 1990s, Thor Beer replaced it with a giant tank.
A three-kilometer beer pipeline was completed in Bruges , Belgium in September 2016 to reduce truck traffic on the city streets. [ 37 ]
The village of Hallstatt in Austria, which is known for its long history of salt mining , claims to contain "the oldest industrial pipeline in the world", dating back to 1595. [ 38 ] It was constructed from 13,000 hollowed-out tree trunks to transport brine 40 kilometres (25 mi) from Hallstatt to Ebensee . [ 39 ]
Between 1978 and 1994, a 15 km milk pipeline ran between the Dutch island of Ameland and Holwerd on the mainland, of which 8 km was beneath the Wadden Sea . Every day, 30,000 litres of milk produced on the island were transported to be processed on the mainland. In 1994, the pipeline was abandoned. [ 40 ]
Rather than transporting fluids, pneumatic tubes are usually used to transport solids in a cylindrical container by compressed air or by partial vacuum. They were most popular in the late 19th and early 20th centuries, and were used to transport small solid objects within a building, e.g. documents in an office or money in a bank. By the 21st century, pneumatic tube transport had been mostly superseded by digital solutions for transporting information, but is still used in cases where convenience and speed in a local environment are important. Hospitals, for example, use them to deliver drugs and specimens. [ 41 ]
In places, a pipeline may have to cross water expanses, such as small seas, straits and rivers. [ 42 ] In many instances, they lie entirely on the seabed. These pipelines are referred to as "marine" pipelines (also, "submarine" or "offshore" pipelines). They are used primarily to carry oil or gas, but transportation of water is also important. [ 42 ] In offshore projects, a distinction is made between a "flowline" and a pipeline. [ 42 ] [ 43 ] [ 44 ] The former is an intrafield pipeline, in the sense that it is used to connect subsea wellheads , manifolds and the platform within a particular development field. The latter, sometimes referred to as an "export pipeline", is used to bring the resource to shore. [ 43 ] The construction and maintenance of marine pipelines imply logistical challenges that are different from those onland, mainly because of wave and current dynamics, along with other geohazards .
In general, pipelines can be classified in three categories depending on purpose:
When a pipeline is built, the construction project not only covers the civil engineering work to lay the pipeline and build the pump/compressor stations, it also has to cover all the work related to the installation of the field devices that will support remote operation.
The pipeline is routed along what is known as a "right of way". Pipelines are generally developed and built using the following stages:
Russia has "Pipeline Troops" as part of the Rear Services , who are trained to build and repair pipelines. Russia is the only country to have Pipeline Troops. [ 46 ]
The U.S. government, mainly through the EPA , the FERC and others, reviews proposed pipeline projects in order to comply with the Clean Water Act , the National Environmental Policy Act , other laws and, in some cases, municipal laws. [ 47 ] [ 48 ] The Biden administration has sought to permit the respective states and tribal groups to appraise and potentially block the proposed projects. [ 49 ]
Field devices are instrumentation, data gathering units and communication systems. The field instrumentation includes flow, pressure, and temperature gauges/transmitters, and other devices to measure the relevant data required. These instruments are installed along the pipeline on some specific locations, such as injection or delivery stations, pump stations (liquid pipelines) or compressor stations (gas pipelines), and block valve stations.
The information measured by these field instruments is then gathered in local remote terminal units (RTU) that transfer the field data to a central location in real time using communication systems, such as satellite channels, microwave links, or cellular phone connections.
Pipelines are controlled and operated remotely, from what is usually known as the "Main Control Room". In this center, all the data related to field measurement is consolidated in one central database. The data is received from multiple RTUs along the pipeline. It is common to find RTUs installed at every station along the pipeline.
The SCADA system at the Main Control Room receives all the field data and presents it to the pipeline operator through a set of screens or Human Machine Interface , showing the operational conditions of the pipeline. The operator can monitor the hydraulic conditions of the line, as well as send operational commands (open/close valves, turn on/off compressors or pumps, change setpoints, etc.) through the SCADA system to the field.
To optimize and secure the operation of these assets, some pipeline companies are using what is called "Advanced Pipeline Applications", which are software tools installed on top of the SCADA system, that provide extended functionality to perform leak detection, leak location, batch tracking (liquid lines), pig tracking, composition tracking, predictive modeling, look ahead modeling, and operator training.
Pipeline networks are composed of several pieces of equipment that operate together to move products from location to location. The main elements of a pipeline system are:
Since oil and gas pipelines are an important asset of the economic development of almost any country, it has been required either by government regulations or internal policies to ensure the safety of the assets, and the population and environment where these pipelines run.
Pipeline companies face government regulation, environmental constraints and social situations. Government regulations may define minimum staff to run the operation, operator training requirements, pipeline facilities, technology and applications required to ensure operational safety. For example, in the State of Washington it is mandatory for pipeline operators to be able to detect and locate leaks of 8 percent of maximum flow within fifteen minutes or less. Social factors also affect the operation of pipelines. Product theft is sometimes also a problem for pipeline companies. In this case, the detection levels should be under two percent of maximum flow, with a high expectation for location accuracy.
Various technologies and strategies have been implemented for monitoring pipelines, from physically walking the lines to satellite surveillance. The most common technology to protect pipelines from occasional leaks is Computational Pipeline Monitoring or CPM. CPM takes information from the field related to pressures, flows, and temperatures to estimate the hydraulic behavior of the product being transported. Once the estimation is completed, the results are compared to other field references to detect the presence of an anomaly or unexpected situation, which may be related to a leak.
The American Petroleum Institute has published several articles related to the performance of CPM in liquids pipelines. The API Publications are:
Where a pipeline containing passes under a road or railway, it is usually enclosed in a protective casing. This casing is vented to the atmosphere to prevent the build-up of flammable gases or corrosive substances, and to allow the air inside the casing to be sampled to detect leaks. The casing vent , a pipe protruding from the ground, often doubles as a warning marker called a casing vent marker . [ 50 ]
Pipelines are generally laid underground because temperature is less variable. Because pipelines are usually metal, this helps to reduce the expansion and shrinkage that can occur with weather changes. [ 51 ] However, in some cases it is necessary to cross a valley or a river on a pipeline bridge . Pipelines for centralized heating systems are often laid on the ground or overhead. Pipelines for petroleum running through permafrost areas as Trans-Alaska-Pipeline are often run overhead in order to avoid melting the frozen ground by hot petroleum which would result in sinking the pipeline in the ground.
Maintenance of pipelines includes checking cathodic protection levels for the proper range, surveillance for construction, erosion, or leaks by foot, land vehicle, boat, or air, and running cleaning pigs when there is anything carried in the pipeline that is corrosive.
US pipeline maintenance rules are covered in Code of Federal Regulations (CFR) sections, 49 CFR 192 for natural gas pipelines, and 49 CFR 195 for petroleum liquid pipelines.
In the US, onshore and offshore pipelines used to transport oil and gas are regulated by the Pipeline and Hazardous Materials Safety Administration (PHMSA). Certain offshore pipelines used to produce oil and gas are regulated by the Minerals Management Service (MMS). In Canada, pipelines are regulated by either the provincial regulators or, if they cross provincial boundaries or the Canada–US border, by the National Energy Board (NEB). Government regulations in Canada and the United States require that buried fuel pipelines must be protected from corrosion . Often, the most economical method of corrosion control is by use of pipeline coating in conjunction with cathodic protection and technology to monitor the pipeline. Above ground, cathodic protection is not an option. The coating is the only external protection.
Pipelines for major energy resources (petroleum and natural gas) are not merely an element of trade. They connect to issues of geopolitics and international security as well, and the construction, placement, and control of oil and gas pipelines often figure prominently in state interests and actions. A notable example of pipeline politics occurred at the beginning of the year 2009, wherein a dispute between Russia and Ukraine ostensibly over pricing led to a major political crisis. Russian state-owned gas company Gazprom cut off natural gas supplies to Ukraine after talks between it and the Ukrainian government fell through. In addition to cutting off supplies to Ukraine, Russian gas flowing through Ukraine—which included nearly all supplies to Southeastern Europe and some supplies to Central and Western Europe —was cut off, creating a major crisis in several countries heavily dependent on Russian gas as fuel. Russia was accused of using the dispute as leverage in its attempt to keep other powers, and particularly the European Union , from interfering in its " near abroad ".
Because the solvent fraction of dilbit typically comprises volatile aromatics such as naptha and benzene , reasonably rapid carrier vaporization can be expected to follow an above-ground spill—ostensibly enabling timely intervention by leaving only a viscous residue that is slow to migrate. Effective protocols to minimize exposure to petrochemical vapours are well-established, and oil spilled from the pipeline would be unlikely to reach the aquifer unless incomplete remediation were followed by the introduction of another carrier (e.g. a series of torrential downpours).
The introduction of benzene and other volatile organic compounds (collectively BTEX ) to the subterranean environment compounds the threat posed by a pipeline leak. Particularly if followed by rain, a pipeline breach would result in BTEX dissolution and equilibration of benzene in water, followed by percolation of the admixture into the aquifer. Benzene can cause many health problems and is carcinogenic with EPA Maximum Contaminant Level (MCL) set at 5 μg/L for potable water . [ 52 ] Although it is not well studied, single benzene exposure events have been linked to acute carcinogenesis. [ 53 ] Additionally, the exposure of livestock, mainly cattle, to benzene has been shown to cause many health issues, such as neurotoxicity , fetal damage and fatal poisoning. [ 54 ]
The entire surface of an above-ground pipeline can be directly examined for material breach. Pooled petroleum is unambiguous, readily spotted, and indicates the location of required repairs. Because the effectiveness of remote inspection is limited by the cost of monitoring equipment, gaps between sensors , and data that requires interpretation, small leaks in buried pipe can sometimes go undetected.
Pipeline developers do not always prioritize effective surveillance against leaks. Buried pipes draw fewer complaints. They are insulated from extremes in ambient temperature , they are shielded from ultraviolet rays , and they are less exposed to photodegradation . Buried pipes are isolated from airborne debris, electrical storms , tornadoes , hurricanes , hail , and acid rain . They are protected from nesting birds, rutting mammals, and stray buckshot. Buried pipe is less vulnerable to accident damage (e.g. automobile collisions ) and less accessible to vandals , saboteurs , and terrorists .
Previous work [ 55 ] has shown that a 'worst-case exposure scenario' can be limited to a specific set of conditions. Based on the advanced detection methods and pipeline shut-off SOP developed by TransCanada, the risk of a substantive or large release over a short period of time contaminating groundwater with benzene is unlikely. [ 56 ] Detection, shutoff, and remediation procedures would limit the dissolution and transport of benzene. Therefore, the exposure of benzene would be limited to leaks that are below the limit of detection and go unnoticed for extended periods of time. [ 55 ] Leak detection is monitored through a SCADA system that assesses pressure and volume flow every 5 seconds. A pinhole leak that releases small quantities that cannot be detected by the SCADA system (<1.5% flow) could accumulate into a substantive spill. [ 56 ] Detection of pinhole leaks would come from a visual or olfactory inspection, aerial surveying, or mass-balance inconsistencies. [ 56 ] It is assumed that pinhole leaks are discovered within the 14-day inspection interval, however snow cover and location (e.g. remote, deep) could delay detection. Benzene typically makes up 0.1 – 1.0% of oil and will have varying degrees of volatility and dissolution based on environmental factors.
Even with pipeline leak volumes within SCADA detection limits, sometimes pipeline leaks are misinterpreted by pipeline operators to be pump malfunctions, or other problems. The Enbridge Line 6B crude oil pipeline failure in Marshall, Michigan , on July 25, 2010, was thought by operators in Edmonton to be from column separation of the dilbit in that pipeline. The leak in wetlands along the Kalamazoo River was only confirmed 17 hours after it happened by a local gas company employee.
Although the Pipeline and Hazardous Materials Safety Administration (PHMSA) has standard baseline incident frequencies to estimate the number of spills, TransCanada altered these assumptions based on improved pipeline design, operation, and safety. [ 56 ] Whether these adjustments are justified is debatable as these assumptions resulted in a nearly 10-fold decrease in spill estimates. [ 55 ] Given that the pipeline crosses 247 miles of the Ogallala Aquifer, [ 57 ] or 14.5% of the entire pipeline length, and the 50-year life of the entire pipeline is expected to have between 11 – 91 spills, [ 55 ] approximately 1.6 – 13.2 spills can be expected to occur over the aquifer. An estimate of 13.2 spills over the aquifer, each lasting 14 days, results in 184 days of potential exposure over the 50 year lifetime of the pipeline.
In the reduced-scope worst-case exposure scenario, the volume of a pinhole leak at 1.5% of max flow-rate for 14 days has been estimated at 189,000 barrels or 7.9 million gallons of oil. [ 55 ] According to PHMSA's incident database, [ 58 ] only 0.5% of all spills in the last 10 years were >10,000 barrels.
Benzene is considered a light aromatic hydrocarbon with high solubility and high volatility. [ clarification needed ] It is unclear how temperature and depth would impact the volatility of benzene, so assumptions have been made that benzene in oil (1% weight by volume) would not volatilize before equilibrating with water. [ 55 ]
Using the octanol-water partition coefficient and a 100-year precipitation event for the area, a worst-case estimate of 75 mg/L of benzene is anticipated to flow toward the aquifer. [ 55 ] The actual movement of the plume through groundwater systems is not well described, although one estimate is that up to 4.9 billion gallons of water in the Ogallala Aquifer could become contaminated with benzene at concentrations above the MCL. [ 55 ] The Final Environmental Impact Statement from the State Department does not include a quantitative analysis because it assumed that most benzene will volatilize. [ 56 ]
One of the major concerns over dilbit is the difficulty in cleaning it up. [ 59 ] When the aforementioned Enbridge Line 6B crude oil pipeline ruptured in Marshall, Michigan in 2010, at least 843,000 gallons of dilbit were spilled. [ 60 ] After detection of the leak, booms and vacuum trucks were deployed. Heavy rains caused the river to overtop existing dams, and carried dilbit 30 miles downstream before the spill was contained. Remediation work collected over 1.1 million gallons of oil and almost 200,000 cubic yards of oil-contaminated sediment and debris from the Kalamazoo River system. However, oil was still being found in affected waters in October 2012. [ 61 ]
Pipelines can help ensure a country's economic well-being and as such present a likely target of terrorists or wartime adversaries.
Fossil fuels can be transported by pipeline, rail, truck or ship, though natural gas requires compression or liquefaction to make vehicle transport economical. For transport of crude oil via these four modes, various reports rank pipelines as proportionately causing less human death and property damage than rail and truck and spilling less oil than truck. [ 7 ]
Pipelines conveying flammable or explosive material, such as natural gas or oil, pose special safety concerns. While corrosion, pressure, and equipment failure are common causes, excavation damage is also a leading accident type that can be avoided by calling 811 before digging near pipelines. [ 62 ]
Pipelines can be the target of vandalism , sabotage , or even terrorist attacks . For example, between early 2011 and July 2012, a natural gas pipeline connecting Egypt to Israel and Jordan was attacked 15 times. [ 74 ] In 2019, a fuel pipeline north of Mexico City exploded after fuel thieves tapped into the line. At least sixty-six people were reported to have been killed. [ 75 ] In war, pipelines are often the target of military attacks, as destruction of pipelines can seriously disrupt enemy logistics . On 26 September 2022, a series of explosions and subsequent major gas leaks occurred on the Nord Stream 1 and Nord Stream 2 pipelines that run to Europe from Russia under the Baltic Sea. The leaks are believed to have been caused by an act of sabotage. [ 76 ] [ 77 ] [ 78 ] | https://en.wikipedia.org/wiki/Pipeline |
Pipeline Pilot is a desktop software application developed by Dassault Systèmes , focused on extract, transform, and load (ETL) processes and data analytics. Since its inception, the software has evolved to offer broader capabilities in various scientific and industrial applications.
Pipeline Pilot uses a visual and dataflow programming interface, allowing users to design workflows for data processing. The software's functionality spans several domains, including cheminformatics , QSAR , [ 1 ] [ 2 ] next-generation sequencing , [ 3 ] image analysis , [ 4 ] and text analytics . [ 5 ] Pipeline Pilot was initially developed by SciTegic , a company that was acquired by BIOVIA in 2004. In 2014, BIOVIA became part of Dassault Systèmes .
Pipeline Pilot is primarily used in industries that require extensive data processing and analysis, including life sciences, materials science, and engineering. The software allows users to create workflows by dragging and dropping functional components that automate data analysis tasks, integrate with databases, and perform various scientific computations. These workflows are referred to as "protocols" and can be shared and reused within teams or organizations.
The product supports multiple programming languages, including Python , .NET , MATLAB , Perl , SQL , Java , VBScript , and R , giving users flexibility in integrating custom code into their workflows. Additionally, Pipeline Pilot offers support for PilotScript, its own scripting language based on PLSQL, which allows users to perform custom data manipulations within their workflows.
Pipeline Pilot has continued to expand its capabilities with additional modules and toolsets for specific scientific tasks, such as next-generation sequencing analysis, cheminformatics, and polymer property prediction.
The interface, known as the Pipeline Pilot Professional Client, allows users to create workflows by selecting and arranging individual data processing units called "components." These components perform a variety of functions such as loading, filtering, joining, or modifying data. Additional components can carry out more complex tasks, such as constructing regression models, training neural networks, or generating reports in formats like PDF.
Pipeline Pilot follows a component-based architecture where components serve as nodes in a workflow, connected by "pipes" that represent data flow in a directed graph . This framework enables the processing of data as it moves between the components.
Users have the flexibility to work with pre-installed components or develop custom ones within workflows, referred to as "protocols." Protocols, which consist of linked components, can be saved, reused, and shared, enabling streamlined data processing. The interface visualizes the connections between components, simplifying complex data workflows by presenting them as sequences of operations.
Pipeline Pilot offers several add-ons called "collections," which are groups of specialized functions aimed at specific domains, such as genetic information processing or polymer analysis. These collections are available to users for an additional licensing fee.
The collections are organized into two main groups: science-specific and generic. The science-specific collections focus on areas like chemistry, biology, and materials modeling, while the generic collections provide tools for reporting, data analysis, and document search. Below is an overview of the available collections: [ 6 ]
Pipeline Pilot is commonly used for processing large and complex datasets, often exceeding 1TB in size. In its early development, Pipeline Pilot introduced a scripting language called "PilotScript," which allows users to write basic scripts that can be integrated into a protocol. Over time, support for additional programming languages was added, including Python, .NET, Matlab, Perl, SQL, Java, VBScript, and R. These languages can be used through APIs that execute commands without requiring the graphical user interface. [ 7 ]
PilotScript, a language modeled on PLSQL , is used within specific components like the "Custom Manipulator (PilotScript)" or "Custom Filter (PilotScript)." An example of a simple PilotScript command is shown below, where a property named "Hello" is added to each record passing through the component with the value "Hello World!": | https://en.wikipedia.org/wiki/Pipeline_Pilot |
Pipeline video inspection is a form of telepresence used to visually inspect the interiors of pipelines , plumbing systems, and storm drains . A common application is for a plumber to determine the condition of small diameter sewer lines and household connection drain pipes.
Older sewer lines of small diameter, typically 6-inch (150 mm), are made by the union of a number of short 3 feet (0.91 m) sections. The pipe segments may be made of cast iron , with 12 feet (3.7 m) to 20 feet (6.1 m) sections, but are more often made of vitrified clay pipe (VCP), a ceramic material, in 3 feet (0.91 m), 4 feet (1.2 m) & 6 feet (1.8 m) sections. Each iron or clay segment will have an enlargement (a "bell") on one end to receive the end of the adjacent segment. Roots from trees and vegetation may work into the joins between segments and can be forceful enough to break open a larger opening in terra cotta or corroded cast iron. Eventually a root ball will form that will impede the flow and this may cleaned out by a cutter mechanism or plumber's snake and subsequently inhibited by use of a chemical foam - a rooticide .
With modern video equipment, the interior of the pipe may be inspected - this is a form of non-destructive testing . A small diameter collector pipe will typically have a cleanout access at the far end and will be several hundred feet long, terminating at a manhole . Additional collector pipes may discharge at this manhole and a pipe (perhaps of larger diameter) will carry the effluent to the next manhole, and so forth to a pump station or treatment plant.
Without regular inspection of public sewers, a significant amount of waste may accumulate unnoticed until the system fails. In order to prevent resulting catastrophic events such as pipe bursts and raw sewage flooding onto city streets, municipalities usually conduct pipeline video inspections as a precautionary measure. [ citation needed ]
The service truck contains a power supply in the form of a small generator, a small air-conditioned compartment containing video monitoring and recording equipment, and related computer and display for feature recording.
At the back end of the truck is a powered reel with video cable reinforced with kevlar or steel wire braid. Some trucks also contain a powered winch that booms out from the truck allowing for lowering and retrieval of the inspection equipment from the pipeline.
Sometimes referred to as a PIG ( pipeline inspection gauge ), the camera and lights are mounted in a swivelling head attached to a cylindrical body. The camera head can pan and tilt remotely. Integrated into the camera head are lighting devices, typically LEDs, for illuminating the pipeline. The camera is connected to display equipment via a long cable wound upon a winch . Some companies, such as Rausch Electronics USA, incorporate a series of lasers in the camera to accurately measure the pipe diameter and other data.
A run to be inspected will either start from an access pipe leading at an angle down to the sewer and then run downstream to a manhole, or will run between manholes.
The service truck is parked above the access point of the pipe. The camera tractor, with a flexible cable attached to the rear, is then lowered into the pipeline. The tractor is moved forward so that it is barely inside of the pipeline. A "down-hole roller" is set up between the camera tractor and the cable reel in the service truck, preventing cable damage from rubbing the top of the pipeline. The operator then retires to the inside of the truck and begins the inspection, remotely operating the camera tractor from the truck. When the inspection is complete or the camera cable is fully extended, the camera tractor is put in reverse gear and the cable is wound up simultaneously. When the camera tractor is near the original access point, the downhole roller is pulled up and the camera tractor is moved into the access point and pulled up to the service truck. A tractor may be used to inspect a complete blockage or collapse that would prevent using a fish and rope as described below.
For small diameter pipes there may not be enough room for the tractor mechanism. Instead, a somewhat rigid "fish" is pushed through the pipe and attached to a rope at the access point near the truck. The fish is then pulled to place the rope along the pipe. The rope is then used to pull the inspection pig and cable through the pipe. Detaching the rope, the cable is then used to pull the pig backwards as the pipe is inspected on the monitor (this is the method shown in the illustrations below).
Much of the analysis of what was viewed in the pipeline is conducted at the time of the inspection by the camera operator, but the entire inspection is always recorded and saved for review. Commercial software and hardware for video pipe inspection are available from a variety of vendors, including Cues, ITpipes, and WinCan.
Depending mostly upon the change in conditions from a previous inspection various improvements may be made to the pipe. It may be cleaned with a rotating root cutting blade on the end of a segmented rotating chain, or a chemical foam may be applied to discourage root growth. If damage is found limited to only a few locations these may be excavated and repaired. Extensive moderate defects may be repaired by lining with a fabric liner that is pulled through the pipe, inflated, and then made rigid through chemical means. Severe damage may require excavation and replacement of the conduit. | https://en.wikipedia.org/wiki/Pipeline_video_inspection |
CORDIC ( coordinate rotation digital computer ), Volder's algorithm , Digit-by-digit method , Circular CORDIC ( Jack E. Volder ), [ 1 ] [ 2 ] Linear CORDIC , Hyperbolic CORDIC (John Stephen Walther), [ 3 ] [ 4 ] and Generalized Hyperbolic CORDIC ( GH CORDIC ) (Yuanyong Luo et al.), [ 5 ] [ 6 ] is a simple and efficient algorithm to calculate trigonometric functions , hyperbolic functions , square roots , multiplications , divisions , and exponentials and logarithms with arbitrary base, typically converging with one digit (or bit) per iteration. CORDIC is therefore also an example of digit-by-digit algorithms . CORDIC and closely related methods known as pseudo-multiplication and pseudo-division or factor combining are commonly used when no hardware multiplier is available (e.g. in simple microcontrollers and field-programmable gate arrays or FPGAs), as the only operations they require are additions , subtractions , bitshift and lookup tables . As such, they all belong to the class of shift-and-add algorithms . In computer science, CORDIC is often used to implement floating-point arithmetic when the target platform lacks hardware multiply for cost or space reasons.
Similar mathematical techniques were published by Henry Briggs as early as 1624 [ 7 ] [ 8 ] and Robert Flower in 1771, [ 9 ] but CORDIC is better optimized for low-complexity finite-state CPUs.
CORDIC was conceived in 1956 [ 10 ] [ 11 ] by Jack E. Volder at the aeroelectronics department of Convair out of necessity to replace the analog resolver in the B-58 bomber 's navigation computer with a more accurate and faster real-time digital solution. [ 11 ] Therefore, CORDIC is sometimes referred to as a digital resolver . [ 12 ] [ 13 ]
In his research Volder was inspired by a formula in the 1946 edition of the CRC Handbook of Chemistry and Physics : [ 11 ]
where φ {\displaystyle \varphi } is such that tan ( φ ) = 2 − n {\displaystyle \tan(\varphi )=2^{-n}} , and K n := 1 + 2 − 2 n {\displaystyle K_{n}:={\sqrt {1+2^{-2n}}}} .
His research led to an internal technical report proposing the CORDIC algorithm to solve sine and cosine functions and a prototypical computer implementing it. [ 10 ] [ 11 ] The report also discussed the possibility to compute hyperbolic coordinate rotation , logarithms and exponential functions with modified CORDIC algorithms. [ 10 ] [ 11 ] Utilizing CORDIC for multiplication and division was also conceived at this time. [ 11 ] Based on the CORDIC principle, Dan H. Daggett, a colleague of Volder at Convair, developed conversion algorithms between binary and binary-coded decimal (BCD). [ 11 ] [ 14 ]
In 1958, Convair finally started to build a demonstration system to solve radar fix –taking problems named CORDIC I , completed in 1960 without Volder, who had left the company already. [ 1 ] [ 11 ] More universal CORDIC II models A (stationary) and B (airborne) were built and tested by Daggett and Harry Schuss in 1962. [ 11 ] [ 15 ]
Volder's CORDIC algorithm was first described in public in 1959, [ 1 ] [ 2 ] [ 11 ] [ 13 ] [ 16 ] which caused it to be incorporated into navigation computers by companies including Martin-Orlando , Computer Control , Litton , Kearfott , Lear-Siegler , Sperry , Raytheon , and Collins Radio . [ 11 ]
Volder teamed up with Malcolm McMillan to build Athena , a fixed-point desktop calculator utilizing his binary CORDIC algorithm. [ 17 ] The design was introduced to Hewlett-Packard in June 1965, but not accepted. [ 17 ] Still, McMillan introduced David S. Cochran (HP) to Volder's algorithm and when Cochran later met Volder he referred him to a similar approach John E. Meggitt (IBM [ 18 ] ) had proposed as pseudo-multiplication and pseudo-division in 1961. [ 18 ] [ 19 ] Meggitt's method also suggested the use of base 10 [ 18 ] rather than base 2 , as used by Volder's CORDIC so far. These efforts led to the ROMable logic implementation of a decimal CORDIC prototype machine inside of Hewlett-Packard in 1966, [ 20 ] [ 19 ] built by and conceptually derived from Thomas E. Osborne 's prototypical Green Machine , a four-function, floating-point desktop calculator he had completed in DTL logic [ 17 ] in December 1964. [ 21 ] This project resulted in the public demonstration of Hewlett-Packard's first desktop calculator with scientific functions, the HP 9100A in March 1968, with series production starting later that year. [ 17 ] [ 21 ] [ 22 ] [ 23 ]
When Wang Laboratories found that the HP 9100A used an approach similar to the factor combining method in their earlier LOCI-1 [ 24 ] (September 1964) and LOCI-2 (January 1965) [ 25 ] [ 26 ] Logarithmic Computing Instrument desktop calculators, [ 27 ] they unsuccessfully accused Hewlett-Packard of infringement of one of An Wang 's patents in 1968. [ 19 ] [ 28 ] [ 29 ] [ 30 ]
John Stephen Walther at Hewlett-Packard generalized the algorithm into the Unified CORDIC algorithm in 1971, allowing it to calculate hyperbolic functions , natural exponentials , natural logarithms , multiplications , divisions , and square roots . [ 31 ] [ 3 ] [ 4 ] [ 32 ] The CORDIC subroutines for trigonometric and hyperbolic functions could share most of their code. [ 28 ] This development resulted in the first scientific handheld calculator , the HP-35 in 1972. [ 28 ] [ 33 ] [ 34 ] [ 35 ] [ 36 ] [ 37 ] Based on hyperbolic CORDIC, Yuanyong Luo et al. further proposed a Generalized Hyperbolic CORDIC (GH CORDIC) to directly compute logarithms and exponentials with an arbitrary fixed base in 2019. [ 5 ] [ 6 ] [ 38 ] [ 39 ] [ 40 ] Theoretically, Hyperbolic CORDIC is a special case of GH CORDIC. [ 5 ]
Originally, CORDIC was implemented only using the binary numeral system and despite Meggitt suggesting the use of the decimal system for his pseudo-multiplication approach, decimal CORDIC continued to remain mostly unheard of for several more years, so that Hermann Schmid and Anthony Bogacki still suggested it as a novelty as late as 1973 [ 16 ] [ 13 ] [ 41 ] [ 42 ] [ 43 ] and it was found only later that Hewlett-Packard had implemented it in 1966 already. [ 11 ] [ 13 ] [ 20 ] [ 28 ]
Decimal CORDIC became widely used in pocket calculators , [ 13 ] most of which operate in binary-coded decimal (BCD) rather than binary. This change in the input and output format did not alter CORDIC's core calculation algorithms. CORDIC is particularly well-suited for handheld calculators, in which low cost – and thus low chip gate count – is much more important than speed.
CORDIC has been implemented in the ARM-based STM32G4 , Intel 8087 , [ 43 ] [ 44 ] [ 45 ] [ 46 ] [ 47 ] 80287 , [ 47 ] [ 48 ] 80387 [ 47 ] [ 48 ] up to the 80486 [ 43 ] coprocessor series as well as in the Motorola 68881 [ 43 ] [ 44 ] and 68882 for some kinds of floating-point instructions, mainly as a way to reduce the gate counts (and complexity) of the FPU sub-system.
CORDIC uses simple shift-add operations for several computing tasks such as the calculation of trigonometric, hyperbolic and logarithmic functions, real and complex multiplications, division, square-root calculation, solution of linear systems, eigenvalue estimation, singular value decomposition , QR factorization and many others. As a consequence, CORDIC has been used for applications in diverse areas such as signal and image processing , communication systems , robotics and 3D graphics apart from general scientific and technical computation. [ 49 ] [ 50 ]
The algorithm was used in the navigational system of the Apollo program 's Lunar Roving Vehicle to compute bearing and range, or distance from the Lunar module . [ 51 ] [ 52 ] CORDIC was used to implement the Intel 8087 math coprocessor in 1980, avoiding the need to implement hardware multiplication. [ 53 ]
CORDIC is generally faster than other approaches when a hardware multiplier is not available (e.g., a microcontroller), or when the number of gates required to implement the functions it supports should be minimized (e.g., in an FPGA or ASIC ).
In fact, CORDIC is a standard drop-in IP in FPGA development applications such as Vivado for Xilinx, while a power series implementation is not due to the specificity of such an IP, i.e. CORDIC can compute many different functions (general purpose) while a hardware multiplier configured to execute power series implementations can only compute the function it was designed for.
On the other hand, when a hardware multiplier is available ( e.g. , in a DSP microprocessor), table-lookup methods and power series are generally faster than CORDIC. In recent years, the CORDIC algorithm has been used extensively for various biomedical applications, especially in FPGA implementations. [ citation needed ]
The STM32G4 , STM32U5 and STM32H5 series and certain STM32H7 series of MCUs implement a CORDIC module to accelerate computations in various mixed signal applications such as graphics for human-machine interface and field oriented control of motors. While not as fast as a power series approximation, CORDIC is indeed faster than interpolating table based implementations such as the ones provided by the ARM CMSIS and C standard libraries. [ 54 ] Though the results may be slightly less accurate as the CORDIC modules provided only achieve 20 bits of precision in the result. For example, most of the performance difference compared to the ARM implementation is due to the overhead of the interpolation algorithm, which achieves full floating point precision (24 bits) and can likely achieve relative error to that precision. [ 55 ] Another benefit is that the CORDIC module is a coprocessor and can be run in parallel with other CPU tasks.
The issue with using Taylor series is that while they do provide small absolute error, they do not exhibit well behaved relative error. [ 56 ] Other means of polynomial approximation, such as minimax optimization, may be used to control both kinds of error.
Many older systems with integer-only CPUs have implemented CORDIC to varying extents as part of their IEEE floating-point libraries. As most modern general-purpose CPUs have floating-point registers with common operations such as add, subtract, multiply, divide, sine, cosine, square root, log 10 , natural log, the need to implement CORDIC in them with software is nearly non-existent. Only microcontroller or special safety and time-constrained software applications would need to consider using CORDIC.
CORDIC can be used to calculate a number of different functions. This explanation shows how to use CORDIC in rotation mode to calculate the sine and cosine of an angle, assuming that the desired angle is given in radians and represented in a fixed-point format. To determine the sine or cosine for an angle β {\displaystyle \beta } , the y or x coordinate of a point on the unit circle corresponding to the desired angle must be found. Using CORDIC, one would start with the vector v 0 {\displaystyle v_{0}} :
In the first iteration, this vector is rotated 45° counterclockwise to get the vector v 1 {\displaystyle v_{1}} . Successive iterations rotate the vector in one or the other direction by size-decreasing steps, until the desired angle has been achieved. Each step angle is γ i = arctan ( 2 − i ) {\displaystyle \gamma _{i}=\arctan {(2^{-i})}} for i = 0 , 1 , 2 , … {\displaystyle i=0,1,2,\dots } .
More formally, every iteration calculates a rotation, which is performed by multiplying the vector v i {\displaystyle v_{i}} with the rotation matrix R i {\displaystyle R_{i}} :
The rotation matrix is given by
Using the trigonometric identity :
the cosine factor can be taken out to give:
The expression for the rotated vector v i + 1 = R i v i {\displaystyle v_{i+1}=R_{i}v_{i}} then becomes:
where x i {\displaystyle x_{i}} and y i {\displaystyle y_{i}} are the components of v i {\displaystyle v_{i}} . Setting the angle γ i {\displaystyle \gamma _{i}} for each iteration such that tan ( γ i ) = ± 2 − i {\displaystyle \tan(\gamma _{i})=\pm 2^{-i}} still yields a series that converges to every possible output value. The multiplication with the tangent can therefore be replaced by a division by a power of two, which is efficiently done in digital computer hardware using a bit shift . The expression then becomes:
and σ i {\displaystyle \sigma _{i}} is used to determine the direction of the rotation: if the angle γ i {\displaystyle \gamma _{i}} is positive, then σ i {\displaystyle \sigma _{i}} is +1, otherwise it is −1.
The following trigonometric identity can be used to replace the cosine:
giving this multiplier for each iteration:
The K i {\displaystyle K_{i}} factors can then be taken out of the iterative process and applied all at once afterwards with a scaling factor K ( n ) {\displaystyle K(n)} :
which is calculated in advance and stored in a table or as a single constant, if the number of iterations is fixed. This correction could also be made in advance, by scaling v 0 {\displaystyle v_{0}} and hence saving a multiplication. Additionally, it can be noted that [ 43 ]
to allow further reduction of the algorithm's complexity. Some applications may avoid correcting for K {\displaystyle K} altogether, resulting in a processing gain A {\displaystyle A} : [ 57 ]
After a sufficient number of iterations, the vector's angle will be close to the wanted angle β {\displaystyle \beta } . For most ordinary purposes, 40 iterations ( n = 40) are sufficient to obtain the correct result to the 10th decimal place.
The only task left is to determine whether the rotation should be clockwise or counterclockwise at each iteration (choosing the value of σ {\displaystyle \sigma } ). This is done by keeping track of how much the angle was rotated at each iteration and subtracting that from the wanted angle; then in order to get closer to the wanted angle β {\displaystyle \beta } , if β n + 1 {\displaystyle \beta _{n+1}} is positive, the rotation is clockwise, otherwise it is negative and the rotation is counterclockwise:
The values of γ n {\displaystyle \gamma _{n}} must also be precomputed and stored. For small angles it can be approximated with arctan ( γ n ) ≈ γ n {\displaystyle \arctan(\gamma _{n})\approx \gamma _{n}} to reduce the table size.
As can be seen in the illustration above, the sine of the angle β {\displaystyle \beta } is the y coordinate of the final vector v n , {\displaystyle v_{n},} while the x coordinate is the cosine value.
The rotation-mode algorithm described above can rotate any vector (not only a unit vector aligned along the x axis) by an angle between −90° and +90°. Decisions on the direction of the rotation depend on β i {\displaystyle \beta _{i}} being positive or negative.
The vectoring-mode of operation requires a slight modification of the algorithm. It starts with a vector whose x coordinate is positive whereas the y coordinate is arbitrary. Successive rotations have the goal of rotating the vector to the x axis (and therefore reducing the y coordinate to zero). At each step, the value of y determines the direction of the rotation. The final value of β i {\displaystyle \beta _{i}} contains the total angle of rotation. The final value of x will be the magnitude of the original vector scaled by K . So, an obvious use of the vectoring mode is the transformation from rectangular to polar coordinates.
In Java the Math class has a scalb(double x,int scale) method to perform such a shift, [ 58 ] C has the ldexp function, [ 59 ] and the x86 class of processors have the fscale floating point operation. [ 60 ]
The number of logic gates for the implementation of a CORDIC is roughly comparable to the number required for a multiplier as both require combinations of shifts and additions. The choice for a multiplier-based or CORDIC-based implementation will depend on the context. The multiplication of two complex numbers represented by their real and imaginary components (rectangular coordinates), for example, requires 4 multiplications, but could be realized by a single CORDIC operating on complex numbers represented by their polar coordinates, especially if the magnitude of the numbers is not relevant (multiplying a complex vector with a vector on the unit circle actually amounts to a rotation). CORDICs are often used in circuits for telecommunications such as digital down converters .
In two of the publications by Vladimir Baykov, [ 61 ] [ 62 ] it was proposed to use the double iterations method for the implementation of the functions: arcsine, arccosine, natural logarithm, exponential function, as well as for the calculation of the hyperbolic functions. Double iterations method consists in the fact that unlike the classical CORDIC method, where the iteration step value changes every time, i.e. on each iteration, in the double iteration method, the iteration step value is repeated twice and changes only through one iteration. Hence the designation for the degree indicator for double iterations appeared: i = 0 , 0 , 1 , 1 , 2 , 2 … {\displaystyle i=0,0,1,1,2,2\dots } . Whereas with ordinary iterations: i = 0 , 1 , 2 … {\displaystyle i=0,1,2\dots } . The double iteration method guarantees the convergence of the method throughout the valid range of argument changes.
The generalization of the CORDIC convergence problems for the arbitrary positional number system with radix R {\displaystyle R} showed [ 63 ] that for the functions sine, cosine, arctangent, it is enough to perform R − 1 {\displaystyle R-1} iterations for each value of i (i = 0 or 1 to n, where n is the number of digits), i.e. for each digit of the result. For the natural logarithm, exponential, hyperbolic sine, cosine and arctangent, R {\displaystyle R} iterations should be performed for each value i {\displaystyle i} . For the functions arcsine and arccosine, two R − 1 {\displaystyle R-1} iterations should be performed for each number digit, i.e. for each value of i {\displaystyle i} . [ 63 ]
For inverse hyperbolic sine and arcosine functions, the number of iterations will be 2 R {\displaystyle 2R} for each i {\displaystyle i} , that is, for each result digit.
CORDIC is part of the class of "shift-and-add" algorithms , as are the logarithm and exponential algorithms derived from Henry Briggs' work. Another shift-and-add algorithm which can be used for computing many elementary functions is the BKM algorithm , which is a generalization of the logarithm and exponential algorithms to the complex plane. For instance, BKM can be used to compute the sine and cosine of a real angle x {\displaystyle x} (in radians) by computing the exponential of 0 + i x {\displaystyle 0+ix} , which is cis ( x ) = cos ( x ) + i sin ( x ) {\displaystyle \operatorname {cis} (x)=\cos(x)+i\sin(x)} . The BKM algorithm is slightly more complex than CORDIC, but has the advantage that it does not need a scaling factor ( K ). | https://en.wikipedia.org/wiki/Pipelined_CORDIC |
A Piper diagram is a graphic procedure proposed by Arthur M. Piper in 1944 for presenting water chemistry data to help in understanding the sources of the dissolved constituent salts in water. This procedure is based on the premise that cations and anions in water are in such amounts to assure the electroneutrality of the dissolved salts, in other words the algebraic sum of the electric charges of cations and anions is zero. [ 1 ]
A Piper diagram is a graphical representation of the chemistry of a water sample or samples.
The cations and anions are shown by separate ternary plots . The apexes of the cation plot are calcium , magnesium and sodium plus potassium cations. The apexes of the anion plot are sulfate , chloride and carbonate plus hydrogen carbonate anions. The two ternary plots are then projected onto a diamond. [ 3 ] The diamond is a matrix transformation of a graph of the anions ( sulfate + chloride / total anions) and cations ( sodium + potassium /total cations). [ 4 ]
The Piper diagram is suitable for comparing the ionic composition of a set of water samples, but does not lend itself to spatial comparisons. For geographical applications, the Stiff diagram and Maucha diagram are more applicable, because they can be used as markers on a map. [ 5 ] Colour coding of the background of the Piper diagram allows linking Piper Diagrams and maps [ 6 ]
Water samples shown on the Piper diagram can be grouped in hydrochemical facies. [ 7 ] The cation and anion triangles can be separated in regions based on the dominant cation(s) or anion(s) and their combination creates regions in the diamond shaped part of the diagram. | https://en.wikipedia.org/wiki/Piper_diagram |
Piperacillin is a broad-spectrum β-lactam antibiotic of the ureidopenicillin class. [ 1 ] The chemical structure of piperacillin and other ureidopenicillins incorporates a polar side chain that enhances penetration into Gram-negative bacteria and reduces susceptibility to cleavage by Gram-negative beta lactamase enzymes. These properties confer activity against the important hospital pathogen Pseudomonas aeruginosa . Thus piperacillin is sometimes referred to as an "anti-pseudomonal penicillin".
When used alone, piperacillin lacks strong activity against the Gram-positive pathogens such as Staphylococcus aureus , as the beta-lactam ring is hydrolyzed by the bacteria's beta-lactamase . [ 2 ]
It was patented in 1974 and approved for medical use in 1981. [ 3 ] Piperacillin is most commonly used in combination with the beta-lactamase inhibitor tazobactam ( piperacillin/tazobactam ), which enhances piperacillin's effectiveness by inhibiting many beta lactamases to which it is susceptible. However, the co-administration of tazobactam does not confer activity against MRSA , as penicillin (and most other beta lactams) do not avidly bind to the penicillin-binding proteins of this pathogen. [ 4 ] The World Health Organization classifies piperacillin as critically important for human medicine. [ 5 ]
Piperacillin is used almost exclusively in combination with the beta lactamase inhibitor tazobactam for the treatment of serious, hospital-acquired infections. This combination is among the most widely used drug therapies in United States non-federal hospitals, accounting for $388M in spending in spite of being a low-cost generic drug . [ 6 ]
Piperacillin-tazobactam is recommended as part of a three-drug regimen for the treatment of hospital-acquired pneumonia suspected as being due to infection by multi-drug resistant pathogens. [ 7 ] It is also one of several antibacterial drugs recommended for the treatment of infections known to be caused by anaerobic Gram-negative rods. [ 8 ]
Piperacillin-tazobactam is recommended by the National Institute for Health and Care Excellence as initial empiric treatment for people with suspected neutropenic sepsis . [ 9 ]
Piperacillin is used to treat patients diagnosed with various internal infections such as abdominal, bacteremia , gynecological , respiratory , and urinary , mainly caused by Pseudomonas aeruginosa and other infectious bacteria. [ 10 ] [ 11 ] [ 12 ] They are primarily used in current and former neutropenic patients, and patients with biliary tract infections. Other uses include applications in surgical infection prophylaxis; in biliary surgery, a single dose of piperacillin is administered intravenously to inhibit the development of acute cholangitis and prevent wound infections. [ 13 ] The combination of piperacillin and an aminoglycoside is commonly used to treat severe infections, but due to the incompatibilities in drug interaction, they are administered separately. [ 12 ] [ 14 ]
The piperacillin-tazobactam (piptaz) antibiotic commonly used with an aminoglycoside retains similar levels of drug safety and efficacy as other antibiotic combinations such as ceftazidime with the aminoglycoside tobramycin in the treatment of patients with hospital acquired pneumonia. In a clinical comparison primarily targeting patients not initially placed in intensive care units, piperacillin-tazobactam was found to produce higher clinical and microbiological rates of success. [ 15 ] By contrast, the drug efficacy of ceftazidime and piperacillin-tazobactam resulted in similar response rates (61.5% and 63.9 respectively) when tobramycin was added into both groups. [ 16 ] Identical evaluations are shown when compared to the imipenem and tobramycin combination, where the administration of piperacillin-tazobactam on patients (especially those under mechanical ventilation) was only consisted of a slightly higher response rate. [ 17 ] [ 18 ]
Piperacillin is not absorbed orally, and must therefore be given by intravenous or intramuscular injection . It has been shown that the bactericidal actions of the drug do not increase with concentrations of piperacillin higher than 4-6× MIC , which means that the drug is concentration-independent in terms of its actions. Piperacillin has instead shown to offer higher bactericidal activity when its concentration remains above the MIC for longer periods of time (50% time above MIC showing the highest activity). This higher activity present in continuous dosing has not been directly linked to clinical outcomes, but however does show promise of lowering possibility of resistance and decreasing mortality. [ 19 ]
Extending the time of piperacillin-tazobactam infusion allows the drugs to maintain the necessary concentrations needed within the body to prevent bacterial growth, enhancing bactericidal activity. [ 20 ] The studies supporting this theory generally administered ~3.375 g of piperacillin-tazobactam every 8 hours during a 4-hour infusion, while for organisms with higher minimum inhibitory concentrations, ~4.5 g of piperacillin-tazobactam was administered every 6 hours during a 3-hour infusion. [ 20 ]
The recommended doses provided by the BNFC for infants with hospital-acquired infections are 90 mg/kg every 8 hours for infants, a maximum of 4.5 g every 6 hours for children, and 4.5 g every 8 hours for children aged 12 and above. A dosage of 90 mg/kg every 6 hours is suggested for infants and children diagnosed with neutropenia. [ 21 ]
Common side effects associated with the administration of piperacillin-tazobactam include: [ 22 ]
Prolonged periods of piperacillin-tazobactam therapy have been associated with the potential development of hematologic adversities such as leukopenia (16.3%), neutropenia (10%), and eosinophilia (10%) in adult patients. [ 23 ] The combination of piperacillin-tazobactam with other antibiotics was found to be a major risk factor for leukopenia as well. Additionally, the chances of developing these illnesses increases in younger patients with fewer conditions, prolonging their time to recover. [ 23 ]
Other cases of adverse effects include instances of renal dysfunction, hepatitis , hyperactivity, anemia , abnormalities in coagulation, and hypokalemia . [ 10 ] Allergic reactions can be induced from the side chains of β-lactam antibiotics such as amoxicillin , or antibodies surrounding the nucleus of penicillin. [ 24 ]
The combination of piperacillin and tazobactam, commonly branded as Zosyn, improves their overall bactericidal activity as amino-benzylpenicillins and ureidopencillins work synergistically with β-lactamase inhibitors . [ 25 ] Concurrent use or unregulated dosages of piperacillin results in increasing levels of piperacillin within the body, prolonging neuromuscular transmission blockages created by non-depolarizing muscle relaxants, and disruptions in urine tests for glucose. [ 10 ] Some compounds that may interfere with the bactericidal activity of piperacillin include chloramphenicol , macrolides , and sulfonamides . [ citation needed ]
Following two studies conducted in 1986 and 2006, [ 26 ] [ 27 ] piperacillin was found to inhibit the removal of methotrexate in animal kidneys. Furthermore, in the presence of piperacillin-tazobactam, the decay time for methotrexate triples in comparison to the normal half-life, leaving the patient exposed to cytotoxic effects produced by the chemical agent. [ 26 ] While penicillin antibiotics generally work synergistically with aminoglycosides by enhancing their penetration of bacterial membranes, they can also work adversely by inactivating them. [ 22 ] A reformulation of ethylenediaminetetraacetic acid and piperacillin-tazobactam has produced results showing an increase in their affinity with amikacin and gentamicin in vitro, enabling the process of simultaneous Y-site infusion to occur. However, tobramycin was found to be incompatible as a combination through Y-site infusion. [ 22 ]
Piperacillin irreversibly binds to the enzyme penicillin-binding proteins , inhibiting the biosynthesis of bacterial cell walls. [ 10 ]
As a β-lactam antibiotic, piperacillin inhibits penicillin-binding proteins, preventing the spread of bacteria and infections. Responsible for catalyzing the cross-linkage between peptidoglycan strands that protect the bacterial cell from osmotic rupture , penicillin-binding proteins are unique to bacterial organisms, where every known bacteria with a peptidoglycan cell wall consists of homologous sub-families. [ 24 ] By sharing a similar stereochemistry with the substrates that bind to penicillin-binding proteins, piperacillin is able to bind to serine residues found at the active site of the enzyme through the formation of a covalent complex, preventing other substrates from binding. [ 28 ] Moreover, this leads to the release of autolysins that break down the bacteria's cell wall. [ 29 ]
Some β-lactamase enzymes also consist of residue at their active site, enabling them to hydrolyze the β-lactam ring found within these antibiotics. [ 28 ] However, this hydrolytic activity is inhibited when piperacillin works in conjunction with tazobactam. Tazobactam binds to these enzymes to form a stable acyl-enzyme complex; similar to one formed during the hydrolysis of the β-lactam ring. Thus, protecting piperacillin from hydrolysis . [ 30 ]
The inclusion of a β-lactamase inhibitor does not always increase drug efficacy. Some bacteria may produce certain types of β-lactamase such as AmpC, which are intrinsically resistant to tazobactam. [ 31 ]
A major mechanism of resistance against piperacillin-tazobactam is Gram-negative bacteria producing β-lactamases. Other currently known mechanisms include mutations in the active site of penicillin-binding proteins, changes in membrane efflux, or bacteria permeability. [ 31 ] Some enzymes, such as extended-spectrum β-lactamase (ESBL) have evolved from narrow-spectrum β-lactamases due to genetic mutations, increasing their capabilities to hydrolyze much broader spectrum penicillin. Due to prior conflicting reports on the drug's affinity with ESBL-producing bacteria, piperacillin-tazobactam treatment for such is not recommended. [ 31 ] Antibiotic resistance occurs sporadically, conferred by the continuous use of piperacillin-tazobactam in situations where it may prove to be ineffective, leading to cases where plasmid-mediated β-lactamases are being produced in bacteria that do not naturally produce it. [ 25 ]
Some Gram-positive bacteria penicillin-binding proteins such as Enterococcus faecium (PBP-5) or Staphylococcus aureus (PBP-2a) are intrinsically antibiotic resistant, consisting of relatively low affinity with piperacillin and therefore high resistance to piperacillin-tazobactam. [ 32 ] [ 33 ] Furthermore, mutations in penicillin-binding proteins cause fluctuations in piperacillin affinity, whereas Streptococcus pneumoniae (PBP-2b) autolytic response is significantly reduced due to decreased affinity with piperacillin. [ 34 ] Although membrane permeability changes are less common as a mechanism of resistance, studies investigating Klebsiella pneumoniae have reported a correlation between decreased permeability of piperacillin and increased SHV-1 β-lactamase production. [ 35 ] [ 36 ]
Piperacillin is generally available in their stable form as crystallized potassium or sodium salt, quickly losing bactericidal activity upon dissolution due to their short half-lives. [ 25 ] As the gastrointestinal tract does not absorb piperacillin and tazobactam, they are dissolved in a solution before being administered to a patient, through parenteral means. [ 31 ] Excreted through renal mechanisms like glomerular or tubular filtration as a component of urine, uncontrolled dosages of the drug can cause renal dysfunction and competitive inhibition of excretion, delaying piperacillin-tazobactam excretion, and endangering patients to drug exposure. [ 25 ]
Although the distribution of the drug remained the same, the half-life for elimination increased by three to five folds for patients diagnosed with renal dysfunction. [ 37 ] Measured by creatinine clearance (CrCl), patients with less than 30 mL/min of clearance had significantly reduced levels of piperacillin/tazobactam excretion, measuring down to 35% of the initial dosage, while the area under the curve (AUC) for piperacillin increased by about three folds for those with less than 20 mL/min. [ 37 ] [ 38 ] A reduced dosage or alteration in the interval of administration is recommended for patients lying under 40 mL/min of CrCl, depending on the severity of dysfunction. [ citation needed ]
Renal is the main pathway for drug elimination for both tazobactam and piperacillin in the body. While there are other non-renal means of drug elimination like hepatobiliary excretion, they occur less frequently. [ 38 ] A substantial amount (~80%) of piperacillin found in urine when excreted through glomerular and tubular filtration is unmetabolized. [ 39 ] Tazobactam renal elimination may be significantly reduced through piperacillin interaction, dropping from 63.7% to 56.8% of the administered dose over a 24-hour period. [ 40 ] Piperacillin may be actively diffused through filtration into the biliary tract during renal clearing, indicated by a generally higher concentration of piperacillin than tazobactam in the bile. [ 41 ] The metabolites that make up the remaining percentage in the excreted urine are composed of M1 (inactive) and N-desethyl-piperacillin (active), formed from the division of β-lactam rings of both tazobactam and piperacillin respectively. [ 42 ]
Due to the hydrophilic nature of piperacillin-tazobactam, a volume distribution of ~15 L amounting to various sites (tissues) is desired, as hydrophilic compounds are not able to pass through plasma membranes as easily as hydrophobic compounds. [ 14 ] [ 38 ] Concentrations often in the range of 90 MIC or above are located in specific areas including the gallbladder, lung, muscle, and skin, making up 16–85% of the plasma concentrations. [ 38 ] The concentration of piperacillin-tazobactam is especially lower in fatty tissue, making up less than 10% of the plasma concentrations. [ 43 ]
Compared to concentration dependent bactericidal antibiotics like aminoglycosides and fluoroquinolones , the antibacterial activity of β-lactam antibiotics are generally more time dependent. [ 44 ] [ 45 ] Unlike the former, when piperacillin-tazobactam concentrations exceed minimum inhibitory concentrations (MIC) of a pathogen by five folds, the exponential relationship between concentration and activity begins to level off. [ 46 ] Otherwise, piperacillin-tazobactam bactericidal efficacy is shown to consist of a strong association with the duration of time the concentration exceeds minimum inhibitory concentrations (T >MIC ). [ 45 ] [ 47 ] When the T >MIC in the serum equates to 60–70% of the frequency for drug administration (dosing interval), maximal activity is achieved against Gram-negative bacteria, while for Gram-positive bacteria it occurs at around 40–50%. [ 44 ] [ 46 ]
Within a 24-hour period in one clinical study, a T >MIC surpassing 60% was found for piperacillin-susceptible bacteria including Escherichia coli , Klebsiella pneumoniae and Staphylococcus aureus in two dosing regimes (4.5 g every 8 hours and 3.375 g every 8 hours). [ 48 ]
The evidence for this was obtained through Monte Carlo experiments procured by a special program (OPTAMA), where for several different scenarios (e.g. hospital acquired infections, secondary peritonitis , skin or soft tissue infections), the probability of attaining those figures were in the ranges of 85–95% and 90–89% respectively for the two regimes. [ 49 ] [ 50 ] [ 51 ] In addition, two similar dosing regimes (3.375 g and 4.5 g every 6 hours) both had lower chances of reaching the 90% T >MIC threshold compared to the 50% threshold against hospital acquired pneumonia pathogens. [ 52 ]
The optimization of piperacillin-tazobactam drug efficiency has been covered by various studies, limiting the focus down to two types of infusions; continuous and intermittent. [ 47 ] [ 53 ] A comparison using the two administration methods under the same dosage regime of 13.5 g per day highlighted no major differences when treating complex intra-abdominal infections. [ 19 ] Furthermore, a follow-up analysis of this trial deduced that both methods of administration lead to higher concentrations compared to the MIC of the pathogens that were used. [ 54 ] Similar results are found in a study where a select number of β-lactam susceptible pathogens consisting of Enterococcus faecalis , Klebsiella pneumoniae and Citrobacter freundii were used to test a ~10 g every 24 hour dosing interval for continuous infusion. [ 47 ] [ 54 ]
Organisms with a piperacillin-tazobactam MIC values equal to 32 or less than 16 μg/mL lead to 50% T >MIC when extended-interval intermittent administrations under two different dosing intervals (8.1 g and 6.75 g every 12 hours) were used against them. [ 53 ] The pharmacodynamic target attainments corresponding to pathogens with MIC values of 16 μg/mL are found to reach 92% when a more traditional 4 hour dosing regime is utilized to administer at irregular intervals. [ 55 ] [ 56 ] One study using the Monte Carlo simulation produced contradicting results to the previous studies, deducing that inadequate pharmacodynamic targets were achieved (T >MIC > 50%) for similar ESBL-producing bacteria, applying to both continuous and high dosage intermittent infusion. [ 57 ]
Derived from “the addition of a hydrophilic heterocyclic group to the α-amino group of ampicillin ”, [ 22 ] the structure consists of a thiazolidine ring conjoined to a β-lactam ring contained within several ring compounds. The addition of this substituent increases the compound's affinity to penicillin-binding protein PBP-3, improving activity against Gram-negative bacteria, and thus broadening its spectrum of activity. [ 58 ] Susceptible β-lactamase producing bacteria such as Staphylococcus spp. or Haemophilus influenzae , the combination of tazobactam (which shares a similar structure to sulbactam , another β-lactamase inhibitor), and piperacillin significantly improves the stability of the drug against β-lactamases. [ 14 ] | https://en.wikipedia.org/wiki/Piperacillin |
A pipette (sometimes spelled as pipet ) is a type of laboratory tool commonly used in chemistry and biology to transport a measured volume of liquid, often as a media dispenser . Pipettes come in several designs for various purposes with differing levels of accuracy and precision , from single piece glass pipettes to more complex adjustable or electronic pipettes. Many pipette types work by creating a partial vacuum above the liquid-holding chamber and selectively releasing this vacuum to draw up and dispense liquid. Measurement accuracy varies greatly depending on the instrument.
The first simple pipettes were made of glass, such as Pasteur pipettes . Large pipettes continue to be made of glass; others are made of squeezable plastic for situations where an exact volume is not required.
During or prior to 1877, Joseph Lister (1827 – 1912) invented the first adjustable micropipette, consisting of a "pipette with a syringe" [ 1 ] (photograph shown at right).
"...by means of this little syringe with a graduated disc and a piston rod in the form of a screw, graduated 2-100ths of a minim , by which means you can, with perfect precision, unit 1-100th of a minim, or 2-100ths, or any number you choose." [ 1 ]
The micropipette was patented in 1957 by Dr Heinrich Schnitger ( Marburg , Germany). The founder of the company Eppendorf , Dr. Heinrich Netheler, inherited the rights and started the commercial production of micropipettes in 1961.
The modern adjustable micropipette is a Wisconsin invention developed through interactions among several people, primarily inventor Warren Gilson and Henry Lardy, a professor of biochemistry at the University of Wisconsin–Madison . [ 2 ] [ 3 ]
Although specific names exist for each type of pipette, in practice, any type can be referred to as a "pipette". [ 4 ] Pipettes that dispense less than 1000 μL are sometimes distinguished as micropipettes.
The terms "pipette" and "pipet" are used interchangeably despite minor historical differences in their usage. [ 5 ]
Air displacement micropipettes are a type of adjustable micropipette that deliver a measured volume of liquid; depending on size, it could be between about 0.1 μL to 1,000 μL (1 mL). These pipettes require disposable tips that come in contact with the fluid.
These pipettes operate by piston -driven air displacement. A vacuum is generated by the vertical travel of a metal or ceramic piston within an airtight sleeve. As the piston moves upward, driven by the depression of the plunger, a vacuum is created in the space left vacant by the piston. The liquid around the tip moves into this vacuum (along with the air in the tip) and can then be transported and released as necessary. These pipettes are capable of being very precise and accurate. However, since they rely on air displacement, they are subject to inaccuracies caused by the changing environment, particularly temperature and user technique. For these reasons, this equipment must be carefully maintained and calibrated, and users must be trained to exercise correct and consistent technique.
The first verified adjustable air displacement micropipette was invented by Joseph Lister during or prior to 1877 (see History section above). [ 1 ] The modern micropipette was patented in 1960 by Dr. Heinrich Schnitger in Marburg , Germany. Afterwards, the co-founder of the biotechnology company Eppendorf , Dr. Heinrich Netheler, inherited the rights and initiated the global and general use of micropipettes in labs. In 1972, the modern adjustable micropipette was invented at the University of Wisconsin-Madison by several people, primarily Warren Gilson and Henry Lardy. [ 6 ]
Types of air displacement pipettes include:
Irrespective of brand or expense of pipette, every micropipette manufacturer recommends checking the calibration at least every six months, if used regularly. Companies in the drug or food industries are required to calibrate their pipettes quarterly (every three months). Schools which are conducting chemistry classes can have this process annually. Those studying forensics and research where a great deal of testing is commonplace will perform monthly calibrations.
To minimize the possible development of musculoskeletal disorders due to repetitive pipetting, electronic pipettes commonly replace the mechanical version.
These are similar to air displacement pipettes, but are less commonly used and are used to avoid contamination and for volatile or viscous substances at small volumes, such as DNA . The major difference is that the disposable tip is a microsyringe (plastic), composed of a capillary and a piston (movable inner part) which directly displaces the liquid.
Volumetric pipettes or bulb pipette allow the user to measure a volume of solution extremely precisely (precision of four significant figures). These pipettes have a large bulb with a long narrow portion above with a single graduation mark as it is calibrated for a single volume (like a volumetric flask ). Typical volumes are 20, 50, and 100 mL. Volumetric pipettes are commonly used to make laboratory solutions from a base stock as well as prepare solutions for titration .
Graduated pipettes are a type of macropipette consisting of a long tube with a series of graduations, as on a graduated cylinder or burette , to indicate different calibrated volumes. They also require a source of vacuum; in the early days of chemistry and biology, the mouth was used. The safety regulations included the statement: "Never pipette by mouth KCN, NH3, strong acids, bases and mercury salts". Some pipettes were manufactured with two bubbles between the mouth piece and the solution level line, to protect the chemist from accidental swallowing of the solution.
Pasteur pipettes are plastic or glass pipettes used to transfer small amounts of liquids, but are not graduated or calibrated for any particular volume. The bulb is separate from the pipette body. Pasteur pipettes are also called teat pipettes , droppers , eye droppers and chemical droppers .
Transfer pipettes , also known as Beral pipettes , are similar to Pasteur pipettes but are made from a single piece of plastic and their bulb can serve as the liquid-holding chamber.
Pipetting syringes are hand-held devices that combine the functions of volumetric (bulb) pipettes, graduated pipettes, and burettes . They are calibrated to ISO volumetric A grade standards. A glass or plastic pipette tube is used with a thumb-operated piston and PTFE seal which slides within the pipette in a positive displacement operation. Such a device can be used on a wide variety of fluids (aqueous, viscous, and volatile fluids; hydrocarbons; essential oils; and mixtures) in volumes between 0.5 mL and 25 mL. This arrangement provides improvements in precision, handling safety, reliability, economy, and versatility. No disposable tips or pipetting aids are needed with the pipetting syringe.
The Van Slyke pipette, invented by Donald Dexter Van Slyke , is a graduated pipette commonly used in medical technology with serologic pipettes for volumetric analysis. [ 7 ]
The Ostwald–Folin pipette, developed by Wilhelm Ostwald and refined by Otto Folin , is a type of volumetric pipette used to measure viscous fluids such as whole blood or serum. [ 8 ] [ 9 ]
The Winkler–Dennis gas combustion pipette, developed by Clemens Winkler and refined by Louis Munroe Dennis, is an apparatus for the controlled reaction of liquids under a mild electric current and a supply of oxygen. [ 10 ]
Glass micropipettes are fabricated in a micropipette puller and are typically used in a micromanipulator . These are used to physically interact with microscopic samples, such as in the procedures of microinjection and patch clamping . Most micropipettes are made of borosilicate , aluminosilicate or quartz with many types and sizes of glass tubing being available. Each of these compositions has unique properties which will determine suitable applications.
A recent introduction into the micropipette field integrates the versatility of microfluidics into a freely positionable pipette platform. At the tip of the device, a localized flow zone is created which allows for constant control of the nanolitre environment, directly in front of the pipette. The pipettes are made from polydimethylsiloxane (PDMS), which is formed using reactive injection molding. Interfacing of these pipettes using pneumatics enables multiple solutions to be loaded and switched on demand, with solution exchange times of 100ms. This type of pipette was invented by Alar Ainla, and currently situated in the Biophysical Technology Lab. [ 11 ] at Chalmers University of Technology in Sweden. [ 12 ]
A zeptolitre pipette has been developed at Brookhaven National Laboratory . The pipette is made of a carbon shell, within which is an alloy of gold-germanium. The pipette was used to learn about how crystallization takes place. [ 13 ]
A variety of devices have been developed for safer, easier, and more efficient pipetting. For example, a motorized pipette controller can aid liquid aspiration or dispensing using volumetric pipettes or graduated pipettes; [ 14 ] a tablet can interact in real-time with the pipette and guide a user through a protocol; [ 15 ] and a pipette station can help to control the pipette tip immersion depth and improve ergonomics. [ 16 ]
Pipette robots are capable of manipulating pipettes just as humans would do. [ 17 ]
Pipette recalibration [ 18 ] is an important consideration in laboratories using these devices. It is the act of determining the accuracy of a measuring device by comparison with NIST traceable reference standards. Pipette calibration is essential to ensure that the instrument is working according to expectations and as per the defined regimes or work protocols. Pipette calibration is considered to be a complex affair because it includes many elements of calibration procedure and several calibration protocol options as well as makes and models of pipettes to consider.
Proper pipetting posture is the most important element in establishing good ergonomic work practices. [ 19 ] During repetitive tasks such as pipetting, maintaining body positions that provide a maximum of strength with the least amount of muscular stress is important to minimize the risk of injury. A number of common pipetting techniques have been identified as potentially hazardous due to biomechanical stress factors. Recommendations for corrective pipetting actions, made by various US governmental agencies and ergonomics experts, are presented below.
Unlike traditional axial pipettes, ergonomic pipetting can affect posture and prevent common pipetting injuries such as carpal tunnel syndrome, tendinitis and other musculoskeletal disorders. [ 20 ] To be "ergonomically correct" significant changes to traditional pipetting postures are essential, like:
minimizing forearm and wrist rotations, keeping a low arm and elbow height and relaxing the shoulders and upper arms.
Typically the pipettes are vertically stored on holder called pipette stands. In case of electronic pipettes, such stands can recharge their batteries. The most advanced pipette stands can directly control electronic pipettes. [ 21 ]
An alternative technology, especially for transferring small volumes (micro and nano litre range) is acoustic droplet ejection . | https://en.wikipedia.org/wiki/Pipette |
Piphilology comprises the creation and use of mnemonic techniques to remember many digits of the mathematical constant π . The word is a play on the word "pi" itself and of the linguistic field of philology .
There are many ways to memorize π , including the use of piems (a portmanteau , formed by combining pi and po em ), which are poems that represent π in a way such that the length of each word (in letters) represents a digit. [ 1 ] Here is an example of a piem: "Now I need a drink, alcoholic of course, after the heavy lectures involving quantum mechanics." Notice how the first word has three letters, the second word has one, the third has four, the fourth has one, the fifth has five, and so on. In longer examples, 10-letter words are used to represent the digit zero , and this rule is extended to handle repeated digits in so-called Pilish writing. The short story " Cadaeic Cadenza " records the first 3,834 digits of π in this manner, and a 10,000-word novel, Not A Wake , has been written accordingly. [ 2 ]
However, poems prove to be inefficient for large memorizations of π . Other methods include remembering patterns in the numbers (for instance, the year 1971 appears in the first fifty digits of π ) and the method of loci (which has been used to memorize π to 67,890 digits). [ 3 ]
Until the 20th century, the number of digits of pi which mathematicians had the stamina to calculate by hand remained in the hundreds, so that memorization of all known digits at the time was possible. [ 5 ] In 1949 a computer was used to calculate π to 2,000 places, presenting one of the earliest opportunities for a more difficult challenge.
Later computers calculated pi to extraordinary numbers of digits (2.7 trillion as of August 2010), [ 4 ] and people began memorizing more and more of the output. The world record for the number of digits memorized has exploded since the mid-1990s, and it stood at 100,000 as of October 2006. [ 6 ] The previous record (83,431) was set by the same person ( Akira Haraguchi ) on July 2, 2005, [ 7 ] and the record previous to that (42,195) was held by Hiroyuki Goto .
An institution from Germany provides the details of the "Pi World Ranking". [ 8 ]
The most common mnemonic technique is to memorize a so-called "piem" (a wordplay on "pi" and "poem") in which the number of letters in each word is equal to the corresponding digit of π. This famous example for 15 digits has several variations, including:
Short mnemonics such as these, of course, do not take one very far down π's infinite road. Instead, they are intended more as amusing doggerel . If even less accuracy suffices, the following examples can be used:
This second one gives the value of π as 3.1415926535, while the first only brings it to the second five. Indeed, many published poems use truncation instead of one of the several roundings , [ citation needed ] thereby producing a less-accurate result when the first omitted digit is greater than or equal to five. It is advantageous to use truncation in memorizing if the individual intends to study more places later on, otherwise one will be remembering erroneous digits.
Another mnemonic is:
In this mnemonic the word "point" represents the decimal point itself.
Yet another example is:
In this example, the spelling of Archimedes is normalised to nine. Although 'Archimedes' is, today, a more correct spelling of the ancient Greek mathematician's name in English, Archimede is also often seen when this mnemonic is given, since Archimède is the more correct spelling in some languages, such as French. This mnemonic also contains a rounding error because the digit represented by the last word "Arkimedes" (9) in 3.141592653589 is followed by 7 in π, which would cause the last two digits to round up.
Longer mnemonics employ the same concept. This example created by Peter M. Brigham incorporates twenty decimal digits:
Some mnemonics, such as this poem which gives the three and the first 20 decimal digits, use the separation of the poem's title and main body to represent the decimal point:
Another, more poetic version is:
Extensions to 30 or 31 decimals of the same proceed as follows:
There are minor variations on the above rhyme, which still allow pi to be worked out correctly. However, one variation replaces the word "lexicon's" with "lesson's" and in doing so, incorrectly indicates that the 18th digit is seven.
The logologist Dmitri Borgmann gives the following 30-word poem in his book, Language on Vacation: An Olio of Orthographical Oddities : [ 12 ]
In the fantasy book, Somewhen by David Saul, a 35-word piem both provides a description of the constant pi and the digits. The text is also laid out as a circle to provide another clue to the readers as to the purpose of the poem. In this example, the word "nothing" is used to represent the digit zero.
The following sonnet is a mnemonic for pi to 75 decimal places in iambic pentameter :
Note that in this example, 10-letter words are used to represent the digit zero .
Other poems use sound as a mnemonic technique, as in the following poem [ 13 ] which rhymes with the first 140 decimal places of pi using a blend of assonance , slant rhyme , and perfect rhyme :
Note that "dreams number us like pi" corresponds to "314159", "runes shift" corresponds to "26", "nights rewind" corresponds to "535" and so on. Sound-based mnemonic techniques, unlike pilish, do not require that the letters in each word be counted in order to recall the digits of pi. However, where sound-based mnemonics use assonance, extra care must be taken to distinguish "nine" and "five," which contain the same vowel sound. In this example, the author assumes the convention that zero is often called "O."
The piku follows the rules of conventional haiku (three lines of 5, 7 and 5 syllables), but with the added mnemonic trick that each word contains the same number of letters as the numerals of pi, e.g.
In 2004, Andrew Huang wrote a song that was a mnemonic for the first fifty digits of pi, titled "I am the first 50 digits of pi". [ 14 ] [ 15 ] The first line is:
In 2013, Huang extended the song to include the first 100 digits of pi, and changed the title to "Pi Mnemonic Song". [ 16 ]
There are piphilologists who have written texts that encode hundreds or thousands of digits. This is an example of constrained writing , known as " Pilish ". For example, Mike Keith 's poem Poe, E.: Near a Raven [ 17 ] represents 740 digits, his story Cadaeic Cadenza encodes 3,835, and his book Not A Wake [ 18 ] extends to 10,000 digits.
It is also possible to use the rhythm and sound of the spoken digits themselves as a memorization device. The mathematician John Horton Conway composed the following arrangement for the first 100 digits,
where the accents indicate various kinds of repetition. [ 19 ]
Another mnemonic system used commonly in the memorization of pi is the Mnemonic major system , where single numbers are translated into basic sounds. A combination of these sounds creates a word, which can then be translated back into numbers. [ 20 ] When combined with the Method of loci , this becomes a very powerful memorization tool.
Kur i hyej, e kryej, sigurisht, po përtoj andaj nuk fitoj
If I start dealing with it, I will do it, but I am lazy therefore I do not win.
(10 decimal places)
Ահա և հեշտ և սիրով սովորեցիր մի պիտանի խրթին թիվ։
Here you easily and lovingly learned a useful intricate number.
It is possible to construct piphilogical poems in Chinese by using homophones or near-homophones of the numbers zero through nine, as in the following well known example which covers 22 decimal places of π. In this example the character meaning "mountain" (山 shān ) is used to represent the number "three" (三 sān ), the character meaning "I" (吾 wú ) is used to represent the number "five" (五 wǔ ), and the characters meaning "temple" (寺 sì ) and "die" (死 sǐ ) are used to represent the number "four" (四 sì ). Some of the mnemonic characters used in this poem, for example "kill" (殺 shā ) for "three" (三 sān ), "jug" (壺 hú ) for "five" (五 wǔ ), "happiness" (樂 lè ) for "six" (六 liù ) and "eat" (吃 chī ) for "seven" (七 qī ), are not very close phonetically in Mandarin/Putonghua .
This can be translated as:
(nine decimal places)
Sám u sebe v hlavě magického pí číslic deset mám.
I have ten digits of magical pi in my head.
(12 decimal places)
Lín a kapr u hráze prohlídli si rybáře, udici měl novou, jikrnáči neuplovou.
Tench and carp by the dam watched the fisher. He has a new rod, fish will not escape.
(13 decimal places)
Dej, ó Bože, a číslo Ludolfovo já navždy pomnu, pro větší naplnění moudrosti početní.
Oh God, let me to remember the pi forever, for the increase of mathematical skills.
(30 decimal places)
Mám ó bože ó velký pamatovat si takový cifer řad, velký slovutný Archimedes, pomáhej trápenému, dej mu moc, nazpaměť nechť odříká ty slavné sice, ale tak protivné nám, ach, číslice Ludolfovy!
Shall I, God oh almighty, remember such a long string of numbers, great and famous Archimedes, help my careworn being, give me the power, to recite by heart all the digits, which may be famous, but also hated by some of us, the digits of Ludolph van Ceulen.
The following poem composed of alexandrines consists of words each with a number of letters that yields π to 126 decimal places: [ 21 ]
Que j’aime à faire apprendre un nombre utile aux sages ! Immortel Archimède, artiste ingénieur, Qui de ton jugement peut priser la valeur ? Pour moi, ton problème eut de pareils avantages. Jadis, mystérieux, un problème bloquait Tout l’admirable procédé, l’œuvre grandiose Que Pythagore découvrit aux anciens Grecs. Ô quadrature ! vieux tourment du philosophe ! Insoluble rondeur, trop longtemps vous avez Défié Pythagore et ses imitateurs. Comment intégrer l’espace plan circulaire ? Former un triangle auquel il équivaudra ? Nouvelle invention : Archimède inscrira Dedans un hexagone; appréciera son aire, Fonction du rayon. Pas trop ne s’y tiendra : Dédoublera chaque élément antérieur; Toujours de l’orbe calculée approchera; Définira limite; enfin, l’arc, le limiteur De cet inquiétant cercle, ennemi trop rebelle ! Professeur, enseignez son problème avec zèle !
How I like to teach this number useful to the wise. Immortal Archimedes, artist, engineer, in your opinion who could estimate its value? For me, your problem had equal advantages. Long ago, mysterious, a problem blocked All the admirable process, the great work That Pythagoras revealed to the Ancient Greeks. Oh quadrature! Old philosopher's torment Unsolvable roundness, for too long you have Defied Pythagoras and his imitators. How to integrate the plain circular space? Form a triangle to which it is equivalent? New invention: Archimedes will inscribe Inside a hexagon; will appreciate its area Function of a ray. Not too much to hold onto there: Will split each previous element; Always the calculated orb will approach Will define the limit; finally, the arc, the limiter Of this disturbing circle, an enemy too rebellious Teacher, teach its problem with zeal
An alternative beginning:
This statement yields π to twenty-two decimal places:
English translation that does not encode pi:
Looser English translation that encodes pi:
Nem a régi s durva közelítés, Mi szótól szóig így kijön Betűiket számlálva. Ludolph eredménye már, Ha itt végezzük húsz jegyen. De rendre kijő még tíz pontosan, Azt is bízvást ígérhetem.
It is not the old and rough approximation, What comes out word by word Counting their letters. Ludolph's result is already here, If we do it, on twenty digits. But come out ten more precisely I also promise definitely.
An interesting (not math themed) alternative:
Bír-e, érez-e ember nyugalmat, Ha lelkét nehéz bús emlék zaklatja. Szüntelen felhőbe burkolózó idő az, Ami változni ámha akarna se tudhat, Mert azt nem írhattya már le halandó kívánsága.
Whether has, whether feels a man a peace of mind If his soul is harassed by heavy, sad memories. The continuously clouded time is, What cannot change although it want, Because it cannot be written by a mortal's desire.
Another alternative:
(7 decimal places)
Níl i mata, a shaoi, eolaíocht nó feidhm.
Wise one, mathematics has neither science nor use.
(30 decimal places)
Non è dato a tutti ricordare il numero aureo del sommo filosofo Archimede. Certuni sostengon che si può ricordar tale numero, ma questi soli poi non recitano che un centone insensato.
Not anybody can retain the golden number of the great philosopher Archimedes. There are who claim it is possible to recall this number, but then they just recite a senseless cento .
(10 decimal places)
Chi è nudo e crepa limonando la tubera, lieto lui crepa
Japanese piphilology has countless mnemonics based on punning words with numbers. This is especially easy in Japanese because there are two or three ways to pronounce each digit, and the language has relatively few phonemes to begin with. For example, to 31 decimal places: [ 22 ]
This is close to being ungrammatical nonsense, but a loose translation prioritizing word order yields:
Japanese children also use songs built on this principle to memorize the multiplication table .
Yielding π to 22 decimal places:
Ἀεὶ ὁ Θεὸς ὀ Μέγας γεωμετρεῖ, τὸ κύκλου μῆκος ἵνα ὁρίσῃ διαμέτρῳ, παρήγαγεν ἀριθμὸν ἀπέραντον, καὶ ὅν, φεῦ, οὐδέποτε ὅλον θνητοὶ θὰ εὕρωσι
The Great God applies geometry forever; To define the length of the circle using its diameter, He produced an infinite number, Which, alas, mortals will never find in its entirety.
خرد | و | دانش | و | آگاهی | دانشمندان .ره | سرمنزل | مقصود | بما | آموزد
Wisdom, science, and the knowledge of scholars, will show us the way to the destination.
Counting the letters in each word (additionally separated by "|") gives 10 decimal places of π : خرد (kherad) = 3, و (va) = 1, دانش (daanesh) = 4, و (va) = 1, آگاهی (aagaahi) = 5, ...
The verse of Polish mathematician Witold Rybczyński (35 decimal places):
Daj, o pani, o boska Mnemozyno , pi liczbę, którą też zowią ponętnie ludolfiną, pamięci przekazać tak, by jej dowolnie oraz szybko do pomocy użyć, gdy się problemu nie da inaczej rozwiązać, pauza — to zastąpić liczbami.
Allow, o lady, o divine Mnemosyne , the pi number, which also is called enticingly the ludolphine, to pass to memory, so as to use it freely and quickly for help, when the problem can not be otherwise resolved, pause — this replace by the numbers.
(Note that the dash stands for zero.)
The verse of Polish mathematician Kazimierz Cwojdziński (23 decimal places):
Kuć i orać w dzień zawzięcie, bo plonów niema bez trudu. Złocisty szczęścia okręcie kołyszesz … Kuć. My nie czekajmy cudu. Robota to potęga ludu.
Hammer and plow by day obstinately, because there are no fruits without effort. Golden ship of happiness, rocking... Hammer. Let us not wait for a miracle. Labor is the power of the people.
(12 decimal places):
Był i jest i wieki sławionym ów będzie, który kół obwód średnicą wymierzył.
There was, and there is, and through centuries renowned will be, who circle's circumference measured with its diameter.
(10 decimal places)
Kto z woli i myśli zapragnie Pi spisać cyfry, ten zdoła
Who out of will and mind shall wish to write the digits of Pi, shall succeed.
An occasionally seen verse related to Mundial Argentina and the Polish football team (30 decimal places):
Już i Lato i Deyna / strzelili do bramki obcej / dwa karne / Lubański dostrzegł mistrza Szarmacha / gdy on tak wypuścił cios szacha / że zdobyć musi cel gry / krzyknął Gol na Mundial Argentyna.
Already both Lato and Deyna have scored two penalty kicks to the opponent's goal. Lubański noticed the champion Szarmach , when he had so released a Shah's strike that he's got to attain the objective of the game; he shouted 'Goal' at the World Cup Argentina. [ 23 ]
(11 decimal places)
Cai a neve e novas ferrovias de marfim serão por casas trocadas.
The snow falls and new ivory railroads will be exchanged by houses.
(8 decimal places)
Com o zero o lente reprovará os alunos.
With zero the university professor will fail the students.
Or in Brazilian Portuguese:
Sim, é útil e fácil memorizar um número grato aos sábios. Nós e todo o mundo guardamos pi usando letra por número. Sou o medo e temor constante do menino vadio.
Yes, it's useful and easy to memorize a number dear to the wisemen. We and all the world memorize pi using letter for number. I'm the constant fear and dread of the stray boy.
A poem written in a more poetic manner:
Sou o amor, o homem impetuoso da libido Homem que ataca mulheres atraentes, meninas pecadoras que no céu imiscuem amor, paixão, fé, desejo, tudo! Até que idolatro com as sereias pecadoras tanta fé! Esbeltas mulheres para o musculado, sereias e fêmeas pecadoras Até idolatram serpentes com ardente macho. O viril desejará as pecadoras iníquas doravante para amar.
I am the love, The impetuous man from the libido Man who attacks attractive women, sinful maidens who on heaven intrude love, passion, faith, desire, everything! I even idolize with the mermaids so much faith! Luscious women for the brawny, sinful mermaids and females They even idolize serpents with the burning buck. The virile man will wish the sinful and the iniquitous henceforth to love.
One of the Romanian versions of Pi poems is: [ 24 ]
Dar o știm, e număr important ce trebuie iubit Din toate numerele însemnate diamant neasemuit, Cei ce vor temeinic asta prețui Ei veșnic bine vor trăi.
But we know, it's an important number which should be loved Of all the significant numbers it is a peerless diamond Those who will sincerely appreciate it Will live happy for ever.
There is another phrase known in Romanian that will help to memorize the number by eight decimal places: Așa e bine a scrie renumitul și utilul număr. — "This is the way to write the renowned and useful number."
Another alternative for 15 decimal places:
Ion a luat o carte, biografie, în latina veche. Are cinci capitole originale clasice latinești. — "Ion has bought a book, a biography, in old latin. It has five classical original latin chapters."
In the Russian language , there is a well-known phrase in the reform of 1917 orthography of old tradition:
Кто и шутя, и скоро пожелаетъ «Пи» узнать число — ужъ знаетъ.
The one who would wish to know the number pi easily and quickly already knows it.
A more modern rhyme is:
Это я знаю и помню прекрасно, Пи многие знаки мне лишни, напрасны.
I know the following and remember it perfectly, Multitudes of the digits of pi are unnecessary and idle for me.
A short approximation is: "Что я знаю о кругах?" (What do I know about circles?)
In addition, there are several nonfolklore verses that simply rhyme the digits of pi "as is"; for examples, see the Russian version of this article .
The Katapayadi System of verses is basically a system of code so that things can be defined in a way so that people can remember. The code is as follows:
With the above key in place, Sri Bharathi Krishna Tirtha in his Vedic Mathematics gives the following verse:
गोपी भाग्य मधुव्रात श्रुङ्गिशो दधिसन्धिग खलजीवित खाताव गलहालारसंधार
If we replace the code from the above table in the above verse, here is what we get.
31 41 5926 535 89793 23846 264 33832792
That gives us π/10=0.31415926535897932384626433832792 [ 25 ]
(16 decimal places)
Čak i Grci i stari Vavilonci su kazali: obime kad deliš krugovim prečnikom dobijaš neophodan nam pi.
Even Greeks and Old Babylonians have told: when dividing circumferences with circle's diameter you obtain the indispensable pi.
The following poem gives π to 30 decimal places.
Naj z rimo v pesmi počastimo še nekoga: Slovi naj kroga krotilec, Sirakužan! Število izračunal nam je res čudovito, tule skrito. Če nemara kdaj sam kod pozabimo brž to pesmico uporabimo.
Now I, even I, would celebrate in rhymes inept, the great immortal Syracusan rivaled nevermore who in his wondrous lore passed on before left men his guidance how to circles mensurate.
The following poem, giving π to 31 decimal places, is well known in Argentina :
Fue y cayó. Y queda solamente la inútil cifra con pocos destinos poderosos, tristes devenires sin el más sencillo bien. Idiota, re idiota, sabe que sus encantos son ya latosos decimales. Pobre...
It went and it fell. And only the useless figure remains, with little powerful destinies, sad future without the simplest goodness. Idiotic, very idiotic, it knows that its charms are now boring decimals. Poor...
Another. This piem gives π (correctly rounded) to 10 decimal places. (If you prefer to not round π, then replace "cosmos" with "cielo".)
Sol y luna y mundo proclaman al eterno Autor del Cosmos.
Sun and moon and world proclaim the eternal Author of the Cosmos. (Or "heaven", not Cosmos, if using "cielo".)
Sen, o alan o çevre bölününce ve sonsuz rakam ile çıkan değişken dizilimli sayısın.
You are the number with infinite digits in changing order, which is found when the circumference and the area is divided.
The record for memorizing digits of π , certified by Guinness World Records , is 70,000 digits, recited in India by Rajveer Meena in 9 hours and 27 minutes on 21 March 2015. [ 26 ]
Limca Book's record for the most decimal places of pi recited by memory is 70,030 digits, recited in India by Suresh Kumar Sharma in 17 hours 14 minutes on October 21, 2015. [ 27 ] [ 28 ] [ 29 ] [ 30 ]
Akira Haraguchi , a retired Japanese engineer, has done recitations of more digits (surpassing 100,000 decimal places on October 3, 2006 [ 31 ] ), but his claims have not yet been verified by Guinness World Records. [ 32 ]
An early record holder for pi memorization was David Fiore, whose record stood as an American record for more than 27 years, which remains the longest time period for an American recordholder. He was the first person to break the 10,000 digit mark. [ 33 ] | https://en.wikipedia.org/wiki/Piphilology |
Within industry, piping is a system of pipes used to convey fluids ( liquids and gases ) from one location to another. The engineering discipline of piping design studies the efficient transport of fluid. [ 1 ] [ 2 ]
Industrial process piping (and accompanying in-line components) can be manufactured from wood , fiberglass , glass , steel , aluminum , plastic , copper , and concrete . The in-line components, known as fittings , [ 3 ] valves , and other devices, typically sense and control the pressure , flow rate and temperature of the transmitted fluid, and usually are included in the field of piping design (or piping engineering), though the sensors and automatic controlling devices may alternatively be treated as part of instrumentation and control design. Piping systems are documented in piping and instrumentation diagrams (P&IDs). If necessary, pipes can be cleaned by the tube cleaning process.
Piping sometimes refers to piping design, the detailed specification of the physical piping layout within a process plant or commercial building. In earlier days, this was sometimes called drafting , technical drawing , engineering drawing , and design, but is today commonly performed by designers that have learned to use automated computer-aided drawing or computer-aided design (CAD) software.
Plumbing is a piping system with which most people are familiar, as it constitutes the form of fluid transportation that is used to provide potable water and fuels to their homes and businesses. Plumbing pipes also remove waste in the form of sewage , and allow venting of sewage gases to the outdoors. Fire sprinkler systems also use piping, and may transport nonpotable or potable water , or other fire-suppression fluids.
Piping also has many other industrial applications, which are crucial for moving raw and semi-processed fluids for refining into more useful products. Some of the more exotic materials used in pipe construction are Inconel , titanium , chrome-moly and various other steel alloys .
Generally, industrial piping engineering has three major sub-fields:
Process piping and power piping are typically checked by pipe stress engineers to verify that the routing, nozzle loads, hangers, and supports are properly placed and selected such that allowable pipe stress is not exceeded under different loads such as sustained loads, operating loads, pressure testing loads, etc., as stipulated by the ASME B31, EN 13480, GOST 32388, RD 10-249 or any other applicable codes and standards. It is necessary to evaluate the mechanical behavior of the piping under regular loads (internal pressure and thermal stresses) as well under occasional and intermittent loading cases such as earthquake, high wind or special vibration, and water hammer. [ 4 ] [ 5 ] This evaluation is usually performed with the assistance of a specialized ( finite element ) pipe stress analysis computer programs such as AutoPIPE, [ 6 ] CAEPIPE, [ 7 ] CAESAR, [ 8 ] PASS/START-PROF, [ 9 ] or ROHR2 .
In cryogenic pipe supports, most steel become more brittle as the temperature decreases from normal operating conditions, so it is necessary to know the temperature distribution for cryogenic conditions. Steel structures will have areas of high stress that may be caused by sharp corners in the design, or inclusions in the material. [ 10 ] When 3D pipe stress is analyzed, it (3D Pipes) will be considered as 3D beams with supports on both sides. Moreover, the 3D pipe stress determines the bending moments of the pipes. Allowable (ASME) Pipe grades permitted for Oil and gas industries are : Carbon Steel Pipes and tubes (A53 Grade [A & B], A106 Grade [B & C]), Low & Intermediate alloy steel Pipes (A333 Grade [6], A335 Grade [P5, P9, P11, P12, P91])
The material with which a pipe is manufactured often forms as the basis for choosing any pipe. Materials that are used for manufacturing pipes include:
Early wooden pipes were constructed out of logs that had a large hole bored lengthwise through the center. [ 12 ] Later wooden pipes were constructed with staves and hoops similar to wooden barrel construction. Stave pipes have the advantage that they are easily transported as a compact pile of parts on a wagon and then assembled as a hollow structure at the job site. Wooden pipes were especially popular in mountain regions where transport of heavy iron or concrete pipes would have been difficult.
Wooden pipes were easier to maintain than metal, because the wood did not expand or contract with temperature changes as much as metal and so consequently expansion joints and bends were not required. The thickness of wood afforded some insulating properties to the pipes which helped prevent freezing as compared to metal pipes. Wood used for water pipes also does not rot very easily. Electrolysis does not affect wood pipes at all, since wood is a much better electrical insulator.
In the Western United States where redwood was used for pipe construction, it was found that redwood had "peculiar properties" that protected it from weathering, acids, insects, and fungus growths. Redwood pipes stayed smooth and clean indefinitely while iron pipe by comparison would rapidly begin to scale and corrode and could eventually plug itself up with the corrosion. [ 13 ]
There are certain standard codes that need to be followed while designing or manufacturing any piping system. Organizations that promulgate piping standards include: | https://en.wikipedia.org/wiki/Piping |
A Piping and Instrumentation Diagram ( P&ID ) is a detailed diagram in the process industry which shows process equipment together with the instrumentation and control devices. It is also called as mechanical flow diagram (MFD). [ 1 ]
Superordinate to the P&ID is the process flow diagram (PFD) which indicates the more general flow of plant processes and the relationship between major equipment of a plant facility.
A piping and instrumentation diagram (P&ID) is defined as follows:
They usually contain the following information:
P&IDs are originally drawn up at the design stage from a combination of process flow sheet data, the mechanical process equipment design, and the instrumentation engineering design. During the design stage, the diagram also provides the basis for the development of system control schemes, allowing for further safety and operational investigations, such as a Hazard and operability study (HAZOP). To do this, it is critical to demonstrate the physical sequence of equipment and systems, as well as how these systems connect.
P&IDs also play a significant role in the maintenance and modification of the process after initial build. Modifications are red-penned onto the diagrams and are vital records of the current plant design.
They are also vital in enabling development of;
P&IDs form the basis for the live mimic diagrams displayed on graphical user interfaces of large industrial control systems such as SCADA and distributed control systems .
Based on STANDARD ANSI / ISA S5.1 and ISO 14617 -6, the P&ID is used for the identification of measurements within the process. The identifications consist of up to 5 letters. The first identification letter is for the measured value, the second is a modifier, 3rd indicates passive/readout function, 4th - active/output function, and the 5th is the function modifier. This is followed by loop number, which is unique to that loop. For instance FIC045 means it is the Flow Indicating Controller in control loop 045. This is also known as the "tag" identifier of the field device, which is normally given to the location and function of the instrument. The same loop may have FT045 - which is the flow transmitter in the same loop.
For reference designation of any equipment in industrial systems the standard IEC 61346 ( Industrial systems, installations and equipment and industrial products — Structuring principles and reference designations ) can be applied. For the function Measurement the reference designator B is used, followed by the above listed letter for the measured variable.
For reference designation of any equipment in a power station the KKS Power Plant Classification System can be applied.
Below are listed some symbols of chemical apparatus and equipment normally used in a P&ID, according to ISO 10628 and ISO 14617 .
Prior to the advent of computer-aided design (CAD) in the late 1980s, P&IDs were drawn by hand. The drawing template shown below, actual size 225.mm by 111 mm, is typical of those used to draw P&IDs.
Piping and instrumentation diagram manual drawing template (1980s). Symbol key: | https://en.wikipedia.org/wiki/Piping_and_instrumentation_diagram |
A fitting or adapter is used in pipe systems to connect sections of pipe (designated by nominal size , with greater tolerances of variance) or tube (designated by actual size, with lower tolerance for variance), adapt to different sizes or shapes, and for other purposes such as regulating (or measuring) fluid flow. [ 1 ] [ 2 ] These fittings are used in plumbing to manipulate the conveyance of fluids such as water for potatory , irrigational , sanitary , and refrigerative purposes, gas , petroleum , liquid waste , or any other liquid or gaseous substances required in domestic or commercial environments, within a system of pipes or tubes, connected by various methods, as dictated by the material of which these are made, the material being conveyed, and the particular environmental context in which they will be used, such as soldering , mortaring , caulking , plastic welding , welding , friction fittings , threaded fittings , and compression fittings .
Fittings allow multiple pipes to be connected to cover longer distances, increase or decrease the size of the pipe or tube, or extend a network by branching, and make possible more complex systems than could be achieved with only individual pipes. Valves are specialized fittings that permit regulating the flow of fluid within a plumbing system.
Standard codes are followed when designing (or manufacturing) a piping system. Organizations which promulgate piping standards include:
Pipes must conform to the dimensional requirements of:
The material with which a pipe is manufactured is often the basis for choosing a pipe. Materials used for manufacturing pipes include:
The bodies of fittings for pipe and tubing are often the same base material as the pipe or tubing connected: copper, steel, PVC, CPVC, or ABS. Any material permitted by the plumbing, health, or building code (as applicable) may be used, but it must be compatible with the other materials in the system, the fluids being transported, and the temperature and pressure inside (and outside) the system. Brass or bronze fittings are common in copper piping and plumbing systems. Fire resistance , earthquake resistance, mechanical ruggedness, theft resistance, and other factors also influence the choice of pipe and fitting materials.
Gaskets are mechanical seals, usually ring-shaped , which seal flange joints. [ 3 ] Gaskets vary by construction, materials and features. Commonly used gaskets are non-metallic (ASME B 16.21), spiral-wound (ASME B 16.20) and ring-joint (ASME B 16.20). Non-metallic gaskets are used with flat- or raised-face flanges. Spiral-wound gaskets are used with raised-face flanges, and ring-joint gaskets are used with ring-type joint (RTJ) flanges. Stress develops between an RTJ gasket and the flange groove when the gasket is bolted to a flange, leading to plastic deformation of the gasket. [ 4 ]
Piping or tubing is usually inserted into fittings to make connections. Connectors are assigned a gender, abbreviated M or F. An example of this is a " 3 ⁄ 4 -inch female adapter NPT ", which would have a corresponding male connection of the same size and thread standard (in this case also NPT).
This section discusses fittings primarily used in pressurized piping systems, though there is some overlap with fittings for low-pressure or non-pressurized systems. Specialized fittings for the latter setups are discussed in the next major subsection.
In plumbing, an adapter is generally a fitting that interfaces two different parts. The term commonly refers to:
An elbow is installed between two lengths of pipe (or tubing) to allow a change of direction, usually a 90° or 45° angle ; 22.5° elbows are also available. The ends may be machined for butt welding , threaded (usually female ), or socketed. When the ends differ in size, it is known as a reducing (or reducer) elbow.
Clarity on the difference between plumbing terminologies and geometric angles:
In plumbing, the term "45-degree elbow" for example, refers to the angle of bend from the original straight pipe position (0 degrees) to the new position (45 degrees), not the actual angle formed by the joint.
On a protractor, the actual angle of the above joint is 135 degrees, an obtuse angle.
This naming convention applies to other plumbing elbows, such as:
- "88 degree elbow" = 92 degrees on a protractor. Visualise bending the left end of the pipe up 88 degrees. Now turn the piece of pipe around so the horizontal piece of pipe is in line with the zero degrees line on the protractor. The protractor will read 92 degrees.
The key point is that the plumbing term focuses on the degree of bend from the original straight pipe, not the resulting angle.
Elbows are also categorized by length. The radius of curvature of a long-radius (LR) elbow is 1.5 times the pipe diameter, but a short-radius (SR) elbow has a radius equal to the pipe diameter. Wide available short elbows are typically used in pressurized systems and physically tight locations.
Long elbows are used in low-pressure gravity-fed systems and other applications where low turbulence and minimum deposition of entrained solids are of concern. They are available in acrylonitrile butadiene styrene (ABS plastic), polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), and copper, and are used in DWV systems , sewage, and central vacuum systems.
A coupling connects two pipes. The fitting is known as a reducing coupling , reducer , or adapter if their sizes differ. There are two types of collars: "regular" and "slip". A regular coupling has a small ridge or stops internally to prevent the over-insertion of a pipe and, thus, under-insertion of the other pipe segment (which would result in an unreliable connection).
A slip coupling (sometimes also called a repair coupling ) is deliberately made without this internal stop to allow it to be slipped into place in tight locations, such as the repair of a pipe that has a small leak due to corrosion or freeze bursting, or which had to be cut temporarily for some reason. Since the alignment stop is missing, it is up to the installer to carefully measure the final location of the slip coupling to ensure that it is located correctly.
A union also connects two pipes but is quite different from a coupling, as it allows future disconnection of the pipes for maintenance. In contrast to a coupling requiring solvent welding , soldering , or rotation (for threaded couplings), a union allows easy connection and disconnection multiple times if needed. It consists of three parts: a nut, a female, and a male end. When the female and male ends are joined, the nut seals the joint by pressing the two ends tightly together. Unions are a type of very compact flange connector.
Dielectric unions , with dielectric insulation, separate dissimilar metals (such as copper and galvanized steel) to prevent galvanic corrosion . When two dissimilar metals are in contact with an electrically conductive solution (ordinary tap water is conductive), they form an electrochemical couple which generates a voltage by electrolysis . When the metals are in direct contact with each other, the electric current from one to the other also moves metallic ions from one to the other; this dissolves one metal, depositing it on the other. A dielectric union breaks the electrical path with a plastic liner between its halves, limiting galvanic corrosion.
Rotary unions allow mechanical rotation of one of the joined parts while resisting leakage.
A nipple is a short stub of pipe, usually male-threaded steel , brass, chlorinated polyvinyl chloride (CPVC), or copper (occasionally unthreaded copper), which connects two other fittings. A nipple with continuous uninterrupted threading is known as a close nipple . Nipples are commonly used with plumbing and hoses.
A reducer reduces the pipe size from a larger to a smaller bore (inner diameter ). Alternatively, reducer may refer to any fitting which causes a change in pipe diameter. [ 15 ] This change may be intended to meet hydraulic flow requirements of the system or adapt to existing piping of a different size. The reduction length is usually equal to the average of the larger and smaller pipe diameters. Although reducers are usually concentric , eccentric reducers are used as needed to maintain the top- or bottom-of-pipe level.
A reducer can also be used either as a nozzle or diffuser, depending on the mach number of the flow. [ citation needed ]
A double-tapped bushing, commonly shortened to bushing, is a fitting which serves as a reducer . It is a sleeve similar to a close nipple , but is threaded on both its inner and outer circumferences. Like a reducer, a double-tapped bushing has two threads of different sizes. A common type of this style fitting is a "hex bushing" with a hex head for installation with a pipe wrench.
A double-tapped bushing is more compact than a reducer but not as flexible. While a double-tapped bushing has a more minor female thread concentric to a larger male thread (and thus couples a smaller male end to a larger female), a reducer may have large and small ends of either gender. If both ends are the same gender, it is a gender-changing reducer .
There are similar fittings for both sweat and solvent joinery. Since they are not "tapped" (threaded), they are simply called reducing bushings .
A tee combines or divides fluid flow. Tees can connect pipes of different diameters, change the direction of a pipe run, or both. Available in various materials, sizes and finishes, they may also be used to transport two-fluid mixtures. [ further explanation needed ] Tees may be equal or unequal in size of their three connections, with equal tees the most common.
This specialized type of tee fitting is used primarily in pressurized hydronic heating systems to divert a portion of the flow from the main line into a side branch connected to a radiator or heat exchanger . The diverter tee allows the flow in the main line, even when the side branch is shut down and not calling for heat. Diverter tees must be heeded with directional markings; a tee installed backwards will function very poorly.
Crosses, also known as four-way fittings or cross branch lines , have one inlet and three outlets (or vice versa), and often have a solvent-welded sockets or female-threaded ends. Cross fittings may stress pipes as temperatures change because they are at the center of four connection points. A tee is steadier than a cross; it behaves like a three-legged stool, and a cross behaves like a four-legged stool. Geometrically , any three non- collinear points can self-consistently define a plane; three legs are inherently stable, whereas four points overdetermine a plane and can be inconsistent, resulting in physical stress on a fitting.
Crosses are common in fire sprinkler systems (where stress caused by thermal expansion is not generally an issue), [ why? ] but are not common in plumbing.
Caps, usually liquid- or gas-tight, cover the otherwise open end of a pipe. The exterior of an industrial cap may be round, square, rectangular, U- or I-shaped, or may have a handgrip.
A plug is a short barbed fitting with a blank end that can only be used with PEX piping to end the continuation of a water line that is no longer in use due to tying in elsewhere within the system or to seal the end of a water line which may be used for future use in the case of additional facilities. All plugs are sealed watertight with a PEX crimp.
A barb (or hose barb ), which connects flexible hose or tubing to pipes, typically has a male-threaded end which mates with female threads. The other end of the fitting has a single- or multi-barbed tube—a long tapered cone with ridges, which is inserted into a flexible hose.
Valves stop (or regulate) the flow of liquids or gases. They are categorized by application, such as isolation, throttling, and non-return.
Isolation valves temporarily disconnect part of a piping system to allow maintenance or repair, for example. Isolation valves are typically left in either a fully open or closed position. A given isolation valve may be in place for many years without being operated but must be designed to be readily operable whenever needed, including for emergency use.
Throttling valves control the amount or pressure of a fluid allowed to pass through and are designed to withstand the stress and wear caused by this operation. Because they may wear out in this usage, they are often installed alongside isolation valves which can temporarily disconnect a failing throttling valve from the rest of the system, so it can be refurbished or replaced.
Non-return or check valves allow the free flow of a fluid in one direction but prevent its flow in a reverse direction. They are often seen in drainage or sewage systems but may also be used in pressurized systems.
Valves are available in several types, based on design and purpose:
Because they operate at low pressure and rely on gravity to move fluids (and entrained solids), drain-waste-vent systems use fittings whose interior surfaces are as smooth as possible. The fittings may be "belled" (expanded slightly in diameter) or otherwise shaped to accommodate the insertion of pipe or tubing without forming a sharp interior ridge that might catch debris or accumulate material, and cause a clog or blockage. [ 16 ] Freshly cut ends of pipe segments are carefully deburred to remove projecting slivers of material which may snag debris (such as hair or fibers) which can build up to cause blockages. This internal smoothness also makes it easier to "snake out" or "rod out" a clogged pipe with a plumber's snake .
Underground piping systems for landscaping drainage or the disposal of stormwater or groundwater also use low-pressure gravity flow, so fittings for these systems resemble larger-scale DWV fittings. With high peak-flow volumes, the design and construction of these systems may resemble those of storm sewers .
Fittings for central vacuum systems are similar to DWV fittings but usually have thinner and lighter construction because the weight of the materials conveyed is less. Vacuum-system designs share with DWV designs the need to eliminate internal ridges, burrs, sharp turns, or other obstructions which might create clogs.
Slip-joint fittings are frequently used in kitchen, bathroom and tub drainage systems. They include a detached (movable) slip nut and slip-joint washer; the washer is made of rubber or nylon. [ 17 ] An advantage of this type of fitting is that the pipe it is connecting to does not need to be cut to a precise length; the slip joint can attach within a range of the end of the inserting pipe. Many slip fittings may be tightened or loosened by hand for easier access to residential drainpipe systems (for example, to clean out a trap or access a drain line past a trap).
DWV elbows are usually long-radius ("sweep") types. [ 18 ] : 61 To reduce flow resistance and solid deposits when the direction of flow is changed, they use a shallow curve with a large radius of curvature . [ 18 ] : 61 [ 19 ] In addition, a well-designed system will often use two 45° elbows instead of one 90° elbow (even a sweep 90° elbow) to reduce flow disruption as much as possible. [ 18 ] : 61
Central vacuum system inlet fittings are intentionally designed with a tighter curvature radius than other bends in the system. If vacuumed debris becomes stuck, it will jam at the inlet, where it is easy to find and remove.
A closet flange (the drainpipe flange to which a flush toilet is attached) is a specialized flange designed to be flush with the floor, allowing a toilet to be installed above it. The flange must be mechanically strong to accommodate slight misalignments or movements and resist corrosion.
Clean-outs are fittings with removable elements, allowing access to drains without removing plumbing fixtures. They are used to allow an auger (or plumber's snake ) to clean out a plugged drain. Since clean-out augers are limited in length, clean-outs should be placed in accessible locations at regular intervals throughout a drainage system (including outside the building). Minimum requirements are typically at the end of each branch in piping, just ahead of each water closet, at the base of each vertical stack and inside and outside the building in the main drain or sewer. Clean-outs usually have screw-on caps or screw-in plugs. They are also known as "rodding eyes", because of the eye-shaped cover plates often used on external versions.
A trap primer automatically injects water into a trap , maintaining a water seal to keep sewer gas out of buildings. It must be installed in an easily accessible place for adjustment, replacement, and repair. A trap primer, a specialized valve , is usually connected to a clean-water supply in addition to a DWV system. [ 20 ] Because of the dual connection, it must be designed to resist the accidental backflow of contaminated water.
A combination tee (combo tee, combo wye, tee-wye, long-sweep wye, or combi) is a tee with a gradually curving central connecting joint: a wye plus an additional 1/8 bend (45°), combined in one 90° unit. It is used in drains for a smooth, gradually curving path to reduce the likelihood of clogs, to ease the pushing of a plumber's snake through a drain system and to encourage water flow in the direction of the drain. [ 21 ] : 165
A sanitary tee has a curved center section. In drainage systems, it is primarily used to connect horizontal drains (including fixture trap arms) to vertical drains. The center connection is generally to the pipe leading to a trap (the trap arm). It must not connect a vertical drain to a horizontal drain because of the likelihood that solids will accumulate at the bottom of the junction and cause a blockage.
Also called a tee with a diverter baffle, a waste tee or an end-outlet tee, it typically connects waste lines before they enter the trap and has a baffle to keep water from one waste pipe from entering the other at the connection. [ 22 ]
This fitting differs from a standard cross in that two ports have curved inlets. Although it has been used in the past for connecting the drains of back-to-back fixtures (such as back-to-back sinks), some current codes—including the 2006 Uniform Plumbing Code in the United States—prohibit the use of this fitting for that purpose and require a double-fixture fitting (double combination wye) to minimize wastewater from one side flowing into the other.
Tee-wyes are similar to tees, except for angling the branch line to reduce friction and turbulence. They are commonly used to attach a vertical drainpipe to a horizontal one, reducing the deposition of entrained solids at the junction. [ 21 ] : 159, 165 [ 21 ] : 165 [ 23 ] Wyes and combo wyes follow a long-sweep pattern relative to sanitary tees and other short-sweep bends, which have a smaller radius and require less space. [ 21 ] : 165
Wyes also have industrial applications. Although low-priced wyes are often spot-welded , industrial-strength wyes are flash-welded at each seam. In long-distance pipeline applications, a specialized wye is used to allow insertion of pigging to keep pipes clear and flowing.
This fitting (also known as a "bungalow fitting" or a "cottage fitting") is a sanitary tee that allows two trap arms to be connected at the same level. A toilet is the main connection, with the option of a right or left-hand outlet to the 3" inlet with a choice of 1-1/2" or 2" in size. It is used to keep stack-vented fixtures high to the joist space and thus conserves the headroom in a basement. As the water closet must be the lowest fixture, the smaller side outlet (usually used to connect the bathtub trap arm) enters slightly above the larger connection. [ citation needed ]
Hydraulic systems use high fluid pressure, such as the hydraulic actuators for bulldozers and backhoes . Their hydraulic fittings are designed and rated for much greater pressure than that experienced in general piping systems, and they are generally not compatible with those used in plumbing. Hydraulic fittings are designed and constructed to resist high-pressure leakage and sudden failure.
Much of the work of installing a piping or plumbing system involves making leakproof, reliable connections, and most piping requires mechanical support against gravity and other forces (such as wind loads and earthquakes ) which might disrupt an installation. [ 24 ] Depending on the connection technology and application, basic skills may be sufficient, or specialized skills and professional licensure may be legally required.
Fasteners join, or affix, two or more objects. Although they are usually used to attach pipe and fittings to mechanical supports in buildings, they do not connect the pipes. Fasteners commonly used with piping are a stud bolt [ 25 ] with nuts (usually fully threaded, with two heavy, hexagonal nuts); a machine bolt and nut; or a powder-actuated tool (PAT) fastener (usually a nail or threaded stud , driven into concrete or masonry).
A threaded pipe has a screw thread at one or both ends for assembly. Steel pipe is often joined with threaded connections; tapered threads are cut into the end of the pipe, and sealant is applied in the form of thread-sealing compound or thread seal tape (also known as PTFE or Teflon tape) and the pipe is screwed into a threaded fitting with a pipe wrench .
Threaded steel pipe is widely used in buildings to convey natural gas or propane fuel and is also a popular choice in fire sprinkler systems due to its resistance to mechanical damage and high heat (including the threaded joints). Threaded steel pipe may still be used in high-security or exposed locations because it is more resistant to vandalism, more difficult to remove, and its scrap value is much lower than copper or brass.
A galvanized coating of metallic zinc was often used to protect steel water pipes from corrosion , but this protective coating eventually would dissolve away, exposing the iron to deterioration. Pipes used to convey fuel gas are often made of "black iron", which has been chemically treated to reduce corrosion, but this treatment does not resist erosion from flowing water. Despite its ruggedness, steel pipe is no longer preferred for conveying drinking water because corrosion can eventually cause leakage (especially at threaded joints), deposits on internal surfaces will eventually restrict flow, and corrosion will shed black or rusty residues into the flowing water.
These disadvantages are less problematic for fire sprinkler installations because standing water in the steel pipes does not flow, except during occasional tests or activation by a fire. Introducing oxygen dissolved in freshwater supplies will cause some corrosion, but this soon stops without any source of additional water-borne oxygen.
In older installations, the threaded brass pipe was similarly used and was considered superior to steel for drinking water because it was more resistant to corrosion and shed much fewer residues into the flowing water.
Assembling threaded pipe is labor-intensive, and requires skill and planning to allow lengths of pipe to be screwed together in sequence. Most threaded-pipe systems require strategically located pipe-union fittings in final assembly. The threaded pipe is heavy and requires adequate attachment to support its weight.
To ensure a comprehensive pressure test, it is crucial to explicitly request a 3.1 certificate in accordance with EN HFF 10204:2004. This certificate attests that the 'metallic products' meet the stipulated order requirements and provides detailed test results. Typically, each fitting is associated with a unique heat number, which corresponds to the information documented in the 3.1 certificate datasheet. [ 26 ] [ 27 ]
A solvent is applied to PVC , CPVC , ABS or other plastic piping to partially dissolve and fuse the adjacent surfaces of piping and fitting. Solvent welding is usually used with a sleeve-type joint to connect pipe and fittings made of the same (or compatible) material.
Unlike metal welding, solvent welding is relatively easy to perform (although care is needed to make reliable joints). Solvents typically used for plastics are usually toxic [ citation needed ] and may be carcinogenic [ citation needed ] and flammable , requiring adequate ventilation.
To make a solder connection, a chemical flux is applied to the inner sleeve of a joint and the pipe is inserted. The joint is then heated, typically by using a propane or MAPP gas torch, although electrically heated soldering tools are sometimes used. Once the fitting and pipe have reached sufficient temperature, solder is applied to the heated joint, and the molten solder is drawn into the joint by capillary action as the flux vaporizes. "Sweating" is a term sometimes used to describe the soldering of pipe joints. [ citation needed ] [ 28 ]
Where many connections must be made in a short period (such as plumbing of a new building), soldering is quicker and less expensive joinery than compression or flare fittings. A degree of skill is needed to make several reliable soldered joints quickly. If flux residue is thoroughly cleaned, soldering can produce a long-lasting connection at a low cost. However, using an open flame for heating joints can present fire and health hazards to building occupants and requires adequate ventilation.
The welding of metals differs from soldering and brazing in that the joint is made without adding a lower-melting-point material (e.g. solder); instead, the pipe or tubing material is partially melted, and the fitting and piping are directly fused. This generally requires piping and fitting to be the same (or compatible) material. Skill is required to melt the joint sufficiently to ensure good fusion while not deforming or damaging the joined pieces.
Properly welded joints are considered reliable and durable. Pipe welding is often performed by specially licensed workers whose skills are retested periodically. For critical applications, every joint is tested with nondestructive methods. Because of the skills required, welded pipe joints are usually restricted to high-performance applications such as shipbuilding , and in chemical and nuclear reactors .
Adequate ventilation is essential to remove metal fumes from welding operations, and personal protective equipment must be worn. Because the high temperatures during welding can often generate intense ultraviolet light , dark goggles or full face shields must be used to protect the eyes. Precautions must also be taken to avoid fires caused by stray sparks and hot welding debris.
Compression fittings (sometimes called "lock-bush fittings") consist of a tapered, concave conical seat; a hollow, barrel-shaped compression ring (sometimes called a ferrule); and a compression nut which is threaded onto the body of the fitting and tightened to make a leakproof connection. They are typically brass or plastic, but stainless steel or other materials may be used.
Although compression connections are less durable than soldered (aka sweated) connections, they are easy to install with simple tools. However, they take longer to install than soldered joints and sometimes require re-tightening to stop slow leaks which may develop over time. Because of this possible leakage, they are generally restricted to accessible locations (such as under a kitchen or bathroom sink) and are prohibited in concealed locations such as the interiors of walls.
Push-to-pull fittings are easily removed compression fitting that allows pipes to be connected with minimal tools. These fittings are similar to regular compression fittings but use an O-ring for sealing and a grip ring to hold the pipe. The main advantage is that it can easily be removed and re-used, it is easy to assemble, and the joints are still rotatable even after assembly. The pipe end should be square, so it sits against the stop in the fittings and does not create turbulence, and needs to be a clean cut to avoid damaging the O-ring during insertion. [ 29 ]
Flared connectors should not be confused with compression connectors, which are generally not interchangeable. Lacking a compression ring, they use a tapered conical shaped connection instead. A specialized flaring tool is used to enlarge tubing into a 45º tapered bell shape matching the projecting shape of the flare fitting. [ 21 ] : 82 The flare nut, which had previously been installed over the tubing, is then tightened over the fitting to force the tapered surfaces tightly together. Flare connectors are typically brass or plastic, but stainless steel or other materials may be used.
Although flare connections are labor-intensive, they are durable and reliable. Considered more secure against leaks and sudden failure, they are used in hydraulic brake systems and in other high-pressure, high-reliability applications.
Flange fittings are generally used to connect valves, inline instruments or equipment nozzles. Two surfaces are joined tightly together with threaded bolts , wedges , clamps, or other means of applying high compressive force. [ 30 ] Although a gasket , packing , or O-ring may be installed between the flanges to prevent leakage, it is sometimes possible to use only a special grease or nothing at all (if the mating surfaces are sufficiently precisely formed). Although flange fittings are bulky, they perform well in demanding applications such as large water supply networks and hydroelectric systems.
Flanges are rated at 150, 300, 400, 600, 900, 1500, and 2500 psi ; or 10, 15, 25, 40, 64, 100, and 150 bars of pressure. Various types of flanges are available, depending on construction. Flanges used in piping (orifice, threaded, slip-on, blind, weld neck , socket weld, lap-joint, and reducing) are available with a variety of facings, such as raised, flat, and ring-joint.
Flange connections tend to be expensive because they require the precision forming of metal. Factory-installed flanges must meet carefully measured dimensional specifications, and pipe segments cut to length on-site require skilled precision welding to attach flanges under more-difficult field conditions.
Manufacturers such as Victaulic and Grinnell produce sleeve-clamp fittings, which replace many flange connections. They attach to the end of a pipe segment via circumferential grooves pressed (or cut) around the end of the pipe to be joined. They are widely used on larger steel pipes and can also be used with other materials.
The chief advantage of these connectors is that they can be installed after cutting the pipe to length in the field. This can save time and considerable expense compared to flange connections, which must be factory- or field-welded to pipe segments. However, mechanically fastened joints are sensitive to residual and thickness stresses caused by dissimilar metals and temperature changes.
A grooved fitting, also known as a grooved coupling, has four elements: grooved pipe, gasket, coupling housing, and nuts and bolts. The groove is made by cold-forming (or machining) a groove at the end of a pipe. A gasket encompassed by coupling housing is wrapped around the two pipe ends, with the coupling engaging the groove; the bolts and nuts are tightened with a socket or impact wrench . The installed coupling housing encases the gasket and engages the grooves around the pipe to create a leakproof seal in a self-restrained pipe joint. There are two types of grooved coupling; a flexible coupling allows a limited amount of angular movement, and a rigid coupling does not allow movement and may be used where joint immobility is required (similar to a flange or welded joint).
Crimped or pressed connections to use special fittings permanently attached to tubing with a powered crimper. The fittings, manufactured with a pre-installed sealant or O-ring , slide over the tubing to be connected. High pressure is used to deform the fitting and compress the sealant against the inner tubing, creating a leakproof seal. [ 31 ]
The advantages of this method are durability, speed, neatness, and safety. The connection can be made even when the tubing is wet. Crimped fittings are suitable for drinking water pipes and other hot-and-cold systems (including central heating). They are more expensive than sweated fittings.
Press fittings with either V and M profile (or contour) in stainless steel, carbon steel, and copper are trendy in Europe, and several manufacturers such as Viega, Geberit, Swiss Fittings, and ISOTUBI, distribute proprietary systems of press fittings. Compared to other connection types, press fittings have the advantages of installation speed and safety. Pressing a stainless steel fitting can be completed within five seconds with the correct equipment. Primary pressing of fittings to pipes or other fittings is performed using electrically powered press equipment, but mechanically driven press equipment is also available. Swiss Fittings is legally protected the German Brand "Pressfittings aus Edelstahl" in the USA. [ 32 ]
Press fittings of some major brands carry a plastic slip [ clarification needed ] around the sleeves on each end of the fitting which falls off when the fitting has been compressed. This allows for a simple identification whether a press fitting has securely been installed.
Press fittings with appropriate and region-specific certification may be used for gas lines. Stainless steel and carbon steel press fittings can withstand up to 16 bars of pressure.
A disadvantage of press fittings is the dead space between the pipe and the fitting, which can possibly rule out use for beverage and food applications.
Elbow 45°, F/F & F/M
Bend 15°, 45°, 75° M/M
Coupling
Coupling Long
Tee
Bend 90° Male Thread
Tee Male
Union Male Coupling
Male Straight Connector
Double Tap Connector 90/90 with Female Thread
Elbow 90° Female Adapter Coupling
Female Straight Connector
Adapter Female Coupling (ISO 228)
Female Coupling
Tee Female
Union Female
Cast iron piping was traditionally made with one "spigot" end (plain, which was cut to length as needed) and one "socket" or "hub" end (cup-shaped). The larger-diameter hub was also called a "bell" because of its shape.
In use, the spigot of one segment was placed into the socket of the preceding one, and a ring of oakum was forced down into the joint with a caulking iron . Then the remainder of the space in the hub was filled up. Ideally, this would be done by pouring molten lead , allowing it to set, and hammering it tightly with a caulking tool. If this was not possible due to position or some other constraint, the joint could be filled with lead wool or rope, which was forcibly compacted one layer at a time. [ 33 ]
This labor-intensive technique was durable if appropriately done but required time, skill, and patience for each joint to be made up. Quicker and lower-cost methods, such as rubber sleeve joints, have replaced mainly leaded hub connections of cast-iron piping in most new installations, but the older technology may still be used for some repairs. [ 21 ] : 149 In addition, some conservative plumbing codes still require leaded hub joints for final connections where the sewer main leaves a building.
Cast iron DWV pipe and fittings are still used in premium construction because they muffle the sound of wastewater rushing through them, [ 21 ] : 149 but today they are rarely joined with traditional lead joints. [ 21 ] : 149 Instead, pipe and fittings with plain (non-belled) connections are butted against each other, and clamped with special rubber sleeve (or "no-hub") fittings. [ 18 ] : 71 The rubber sleeves are typically secured with stainless steel worm drive clamping bands, which compress the rubber to make a tight seal around the pipes and fittings. These pipe clamps are similar to hose clamps , but are heavier-duty and ideally are made completely of stainless steel (including the screw) to provide maximum service life. [ 21 ] : 149 [ 18 ] : 71 Optionally, the entire rubber sleeve may be jacketed with thin sheet metal, to provide extra stiffness, durability, and resistance to accidental penetration by a misplaced nail or screw. [ 21 ] : 149 Although the fittings are not cheap, they are reasonably durable (the rubber is typically neoprene or flexible PVC ).
An alternative design also allows the selective use of belled fittings made entirely of flexible rubber, including more-complex shapes such as wyes or tee-wyes. [ 18 ] : 69 They are secured to cast iron pipe segments by use of stainless steel worm drive clamps. Because these fittings are not as stiff as traditional cast-iron fittings, the heavy pipe segments may need better anchoring and support to prevent unwanted movement. [ 21 ] : 150 The lighter rubber fittings may not muffle sound as well as the heavy cast-iron fittings.
An advantage of flexible rubber fittings is that they can accommodate small misalignments and can be flexed slightly for installation in tight locations. [ 21 ] : 147, 149 A flexible fitting may be preferred to connect a shower or heavy tub to the drainage system without transmitting slight movements or stresses, which could eventually cause cracking. [ 21 ] : 159 Flexible fittings may also be used to reduce the transmission of vibration into the DWV system.
If necessary, clamped joints can be disassembled later, and the fittings and pipe may be reconfigured. However, it is often not customary to re-use the clamps and rubber sleeves, which their previous installation may deform and may not seal well after rearranging. Clamped fittings may occasionally need to be disassembled to provide access for " snaking " or "rodding-out" with a unique tool to clear blockage or clogs. [ 18 ] : 69 This is also an indication that a clean-out fitting could be installed to provide easier future access. | https://en.wikipedia.org/wiki/Piping_and_plumbing_fitting |
Piping corrosion circuit or Corrosion loop / Piping Circuitization and Corrosion Modelling, is carried out as part of either a Risk Based Inspection analysis (RBI) or Materials Operating Envelope analysis (MOE). It is the systematization of the piping components versus failure modes analysis into materials operating envelope. It groups piping materials / chemical make-up into systems / sub systems and assigns corrosion mechanisms. These are then monitored over the operating lifetime of the facility. This analysis is performed on circuit inspection results to determine and optimize circuit corrosion rates and measured thickness/dates for circuit components. Corrosion Circuits are utilized in the Integrity Management Plan (IMP) which forms a part of the overall Asset integrity management system and is an integral part of any RBI analysis. Many times a "system" will be a broad overview of the facilities process flow, broken by stream constituents, while a circuit level analysis breaks systems into smaller "circuits" that group common metallurgies, equal (or roughly equal) temperatures and pressures, and expected damage mechanisms.
It is carried out in order to:
Typically, this is performed at the outset of any Mechanical Integrity program i.e. as the facility is built, modified and operated throughout its life.
General Requirements of Circuitization:
This corrosion -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Piping_corrosion_circuit |
The Pirelli Internetional Award was an international multimedia competition for the communication of science & technology conducted entirely on the internet , which was awarded from 1997 to 2007. Awards were granted to the best multimedia presentations focussing on themes involving the diffusion of science and technology. The multimedia presentations must deal with either physics , chemistry , mathematics , life sciences , or the enabling information and communication technologies that empower multimedia itself. According to Marco Tronchetti Provera , President of the Pirelli Group , the award was established in the belief that the diffusion of social, economic and technological advances are as important as their discovery. [ 1 ]
An international jury of notable people including Nobel Prize laureates reviewed the top entries. With an overall budget prize of 105,000 euro (about US$ 130,000), awards were granted in the following major categories: physics , chemistry , mathematics , life sciences , and information and communications technology . [ 2 ] [ 3 ] [ 4 ]
Physics: This category rewarded the best multimedia works coming from the field of physics and amounted to an award of 15,000 euro. [ 5 ]
Chemistry: This category rewarded the best multimedia works coming from the field of chemistry and amounted to an award of 15,000 euro. [ 6 ]
Mathematics: This category rewarded the best multimedia work coming from the field of mathematics and amounted to an award of 15,000 euro. [ 7 ]
Life Sciences:This category rewarded the best multimedia work coming from the field of life sciences and amounted to an award of 15,000 euro. [ 8 ] [ 9 ]
Information and Communications Technology: This special category prize rewarded those multimedia works which represented a relevant contribution to Information and Communications Technology by means of a product, process, or service, and was deemed to be of particular significance to the jury in that the Pirelli Internetional Award was predicated in large degree to contributions such as these. The Information and Communications Technology prize amounted to 15,000 euro. [ 10 ] [ 11 ]
Top Pirelli Prize: The Top Pirelli Prize was awarded by the international jury to a multimedia work which best embodied the philosophy of the Pirelli International Award. It amounted to an additional 10,000 euro on top of the monetary award granted in any of the five regular categories. The Top Pirelli Prize was first awarded in 2001 (five years after the inception of the Pirelli Award) to Robert C. Michelson for his work on the Entomopter , a biologically inspired insect-like aerial robot. [ 12 ] [ 13 ] [ 14 ]
In a July 2, 2008 communique, author and manager of the Pirelli Internetional Award, Massimo Armeni, announced that Pirelli would no longer be conducting the award on an annual basis, however no indication was given as to when the next competition for the award would be announced. [ 15 ] | https://en.wikipedia.org/wiki/Pirelli_Internetional_Award |
Pirepemat ( INN Tooltip International Nonproprietary Name ; developmental code name IRL752 or IRL-752 ) is a drug which is under development for the prevention of falls in people with Parkinson's disease and Parkinson's disease dementia . [ 2 ] [ 3 ] [ 4 ] [ 5 ] [ 1 ] [ 6 ] It has been referred to as a " nootrope " (i.e., nootropic or cognitive enhancer). [ 7 ]
Pirepemat shows affinity for several neurotransmitter receptors and transporters . [ 8 ] [ 9 ] [ 5 ] These include the serotonin 5-HT 7 receptor (K i = 980 nM), the sigma σ 1 receptor (K i = 1,200 nM), the serotonin transporter (SERT) (K i = 2,500 nM), the α 2C -adrenergic receptor (K i = 3,800 nM), the α 2A -adrenergic receptor (K i = 6,500 nM), the serotonin 5-HT 2C receptor (K i = 6,600 nM), the serotonin 5-HT 2A receptor (K i = 8,100 nM), and the norepinephrine transporter (NET) (K i = 8,100 nM). [ 8 ] [ 9 ] [ 5 ] It also shows affinity for the rat κ-opioid receptor (KOR) (K i = 6,500 nM) and has weak affinity for the α 1 -adrenergic receptor (K i = 21,000 nM). [ 5 ] The drug was an antagonist or inhibitor at all assessed targets (which included some but not all of the preceding sites). [ 8 ] [ 9 ] [ 5 ]
Pirepemat has been described as a "cortical enhancer" and has been reported to region-specifically increase norepinephrine , dopamine , and acetylcholine levels in the cerebral cortex . [ 2 ] [ 5 ] Serotonin 5-HT 7 receptor antagonism and α 2 -adrenergic receptor antagonism were hypothesized to underlie these effects. [ 9 ] [ 5 ] In animals, pirepemat has been found to reverse hypoactivity induced by the dopamine depleting agent tetrabenazine whilst not increasing basal locomotor activity and not affecting or minimally influencing dextroamphetamine - and dizocilpine -induced locomotor hyperactivity . [ 6 ] [ 5 ]
The drug was reported to improve motivation and reduce apathy in people with Parkinson's disease in a phase 2a clinical trial . [ 10 ] [ 2 ] [ 6 ]
As of September 2024, pirepemat is in phase 2 clinical trials for Parkinson's disease. [ 9 ] [ 8 ] A phase 3 trial is being planned. [ 9 ] The drug was also under development for the treatment of "behavioral disorders" and attention deficit hyperactivity disorder (ADHD). [ 9 ] However, no recent development for the former indication has been reported and development for ADHD was discontinued. [ 9 ] In August 2020, pirepemat received an INN Tooltip International Nonproprietary Name with a novel suffix reflecting its reputedly new and unique mechanism of action . [ 11 ] [ 7 ] Pirepemat is under development by Integrative Research Laboratories (IRLAB). [ 9 ] | https://en.wikipedia.org/wiki/Pirepemat |
Pirkle's alcohol is an off-white, crystalline solid that is stable at room temperature when protected from light and oxygen. This chiral molecule is typically used, in nonracemic form, as a chiral shift reagent in nuclear magnetic resonance spectroscopy , in order to simultaneously determine absolute configuration and enantiomeric purity of other chiral molecules. The molecule is named after William H. Pirkle, Professor of Chemistry at the University of Illinois whose group reported its synthesis and its application as a chiral shift reagent. [ 1 ]
Pirkle's alcohol is synthesized by trifluoroacetylation of anthracene , to yield trifluoromethyl 9-anthryl ketone . Trifluoromethyl 9-anthryl ketone may be reduced with a chiral hydride reagent prepared from lithium aluminium hydride and (4S,5S)-(–)-2-ethyl-4-hydroxymethyl-5-phenyl-2-oxazoline to generate Pirkle's alcohol with R absolute configuration. Alternatively, trifluoromethyl 9-anthryl ketone may be reduced with sodium borohydride to generate racemic Pirkle's alcohol. The enantiomers are then derivatized to diastereomeric carbamates using enantioenriched 1-(1-Naphthyl)ethyl isocyanate (also developed by Pirkle). These diastereomers may be separated by column chromatography and hydrolyzed to obtain each enantiomer of Pirkle's alcohol in enantiopure form.
The determination of enantiomeric purity and absolute configuration is frequently necessary in organic synthesis . Pirkle's alcohol is applied to obtain this information by NMR spectroscopy . When Pirkle's alcohol is in solution with an ensemble of chiral molecules, short-lived diastereomeric solvates may be formed from Pirkle's alcohol and the enantiomers of the analyte. Enantiomorphic protons of the analyte enantiomers, which without Pirkle's alcohol are indistinguishable by NMR, become diastereomorphic when the analyte interacts with Pirkle's alcohol, and appear as different signals in an NMR spectrum. The relative magnitude of the signals quantitatively reveals the enantiomeric purity of the analyte. Also, a model of the solvated complex may be used to deduce absolute configuration of an enantioenriched analyte. | https://en.wikipedia.org/wiki/Pirkle's_alcohol |
A pirn is a rod onto which weft thread is wound for use in weaving . [ 1 ] [ 2 ] Unlike a bobbin , it is fixed in place, and the thread is delivered off the end of the pirn rather than from the centre. A typical pirn is made of wood or plastic and is slightly tapered for most of its length, flaring out more sharply at the base, which fits over a pin in the shuttle. Pirns are wound from the base forward in order to ensure snag-free delivery of the thread, unlike bobbins, which are wound evenly from end to end.
Pirns became important with the development of the flying shuttle , though they are also used with other end delivery shuttles. Power looms which use pirns generally have automatic changing mechanisms which remove the spent pirn from the shuttle and replaces it with a fresh one, thus allowing for uninterrupted weaving.
This article about textiles is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pirn |
Pisces V is a type of crewed submersible ocean exploration device, powered by battery, and capable of operating to depths of 2,000 metres (6,600 ft), a depth that is optimum for use in the sea waters around the Hawaiian Islands . It is used by scientists to explore the deep sea around the underwater banks in the main Hawaiian Islands, as well as the underwater features and seamounts in the Northwestern Hawaiian Islands, specifically around Kamaʻehuakanaloa Seamount (formerly Loihi). [ 1 ]
In 1973, Pisces V took part in the rescue of Roger Mallinson and Roger Chapman , who were trapped on the seabed in Pisces V ' s sister submersible Pisces III . [ 2 ] In August 2002, Pisces V and her sister Pisces IV discovered a World War II Japanese midget submarine outside of Pearl Harbor which had been sunk by the destroyer USS Ward in the first American shots fired in World War II. In 2011, marine scientists from HURL celebrated the 1,000 dives of Pisces V and Pisces IV . [ 3 ]
The advantage of having two is that it allows preparation for an emergency. While one of the submersibles is conducting its dive, the other remains at readiness should there be an emergency, needing to be boarded on ship and hurried to the site of the problem. Such an emergency could include the submersible becoming tangled in fishing nets or entrapped in rocks or debris on the ocean floor. In such cases, the second heads to the rescue. There are also research experiments where it is advantageous to use the two vessels together. [ 1 ]
In August 2002, Pisces V and her sister vessel Pisces IV discovered a Japanese midget submarine ; sunk on December 7, 1941 by the destroyer USS Ward in the first American shots fired in World War II, the submarine was hit by a 4"/50 caliber gun shot and depth charged shortly before the attack on Pearl Harbor began. The submarine was found in 400 metres (1,300 ft) of water about 5 miles (8.0 km) off the mouth of Pearl Harbor . [ 4 ] [ 5 ] This was the culmination of a 61-year search for the vessel and has been called "the most significant modern marine archeological find ever in the Pacific, second only to the finding of Titanic in the Atlantic". [ 4 ] In 2003, Pisces V visited the Japanese midget submarine it had found in Pearl Harbor the year before. The U.S. State Department worked in conjunction with the Japanese Foreign Ministry to determine Japanese wishes regarding the fate of the midget submarine. [ 6 ] The submersibles are used by HURL as teaching devices. In 2008, two members of the Tampa Bay Chapter of SCUBAnauts were invited to team with HURL and to visit the historic wreck of the Japanese submarine. One SCUBAnaut said as he stepped on Pisces V that "it looked and felt as if I were in a space shuttle preparing for lift-off". [ 7 ] A mock-up of the control panel of Pisces V can be visited by the public at the Mokupāpapa Discovery Center in Hilo, Hawaii . [ 8 ]
On March 5, 2009, scientists discovered seven new species of bamboo coral , six of which may be of a new genus, an extraordinary finding in a genus so broad. They were able to find these specimens through the use of Pisces V which allowed them to reach depths beyond those attained by scuba divers. [ 9 ] [ 10 ] They also discovered a giant sponge approximately three feet tall and three feet wide that scientists named the "cauldron sponge". [ 11 ] | https://en.wikipedia.org/wiki/Pisces_V |
In mathematics , Pisier–Ringrose inequality is an inequality in the theory of C*-algebras which was proved by Gilles Pisier in 1978 affirming a conjecture of John Ringrose . It is an extension of the Grothendieck inequality .
Theorem . [ 1 ] [ 2 ] If γ {\displaystyle \gamma } is a bounded, linear mapping of one C*-algebra A {\displaystyle {\mathfrak {A}}} into another C*-algebra B {\displaystyle {\mathfrak {B}}} , then
for each finite set { A 1 , A 2 , … , A n } {\displaystyle \{A_{1},A_{2},\ldots ,A_{n}\}} of elements A j {\displaystyle A_{j}} of A {\displaystyle {\mathfrak {A}}} . | https://en.wikipedia.org/wiki/Pisier–Ringrose_inequality |
Pisoniviricetes is a class of positive-strand RNA viruses which infect eukaryotes . [ 1 ] [ 2 ] A characteristic of the group is a conserved 3C - like protease from the PA clan of proteases for processing the translated polyprotein . [ 3 ] [ 4 ] [ 5 ] The name of the group is a portmanteau of member orders " pi cornavirales, so belivirales, ni dovirales" and - viricetes which is the suffix for a virus class . [ 6 ]
The following orders are recognized:
This virus -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pisoniviricetes |
On a firearm or other tools , a pistol grip is a distinctly protruded handle underneath the main mechanism, to be held by the user's hand at a more vertical (and thus more ergonomic) angle, similar to how one would hold a conventional pistol . [ 1 ]
In firearms, the pistol grip is located behind the trigger and generally held by the hand that operates the trigger. Rifles and shotguns without pistol grips are generally referred to as having "straight" or "upland" (shotguns only) style stocks . Some firearms, starting from a 1840s Belgian carbine, [ 2 ] and some automatic weapons in the 20th century (e. g., Chauchat MG, Thompson submachine gun , AK-47 assault rifle ), have a second frontal pistol grip (or foregrip ) on the firearm's fore-end to be used by the support hand for better stability in operation.
Pistol grips can also serve multiple functions, such as a magazine housing (in semi-automatic pistols ), bipod (in some foregrips) or tool storage device (for spare batteries , gun oil / cleaner , hex keys , etc.). In few firearms, like the Finnish Kk 62 light machine gun , the pistol grip is also used as a handle to charge the weapon.
Pistol grips are regarded as a defining feature in United States gun law . Pistol grips that protrude below the weapon but are not integrated with the shoulder stock (i.e. as part of a thumbhole stock ) are currently regulated in some states and were regulated by the now-expired Federal Assault Weapons Ban .
Tools with pistol-style grips run the range from hand tools such as bar clamps and hand saws , to power tools such as electric drills and pneumatic surgical sternal saws . Often the word "gun" appears in the name of pistol gripped tools such as the glue gun , caulking gun and nail gun . Spray painters and grinders also often include this feature for added precision control.
One of the reasons that pistol-style grips are so common in machinery is because it is possible to ergonomically position the operating controls for use with minimal hand movement. For example, on self-loading rifles such as the AR-15 and M16 rifle , the user's grip hand can manipulate the trigger and magazine release with only the index finger , while using the thumb to control the safety or selector switch, all without needing to remove the palm from the grip. | https://en.wikipedia.org/wiki/Pistol_grip |
Piston effect refers to the forced-air flow inside a tunnel or shaft caused by moving vehicles. [ 1 ] It is one of numerous phenomena that engineers and designers must consider when developing a range of structures.
In open air, when a vehicle travels along, air pushed aside can move in any direction except into the ground. Inside a tunnel, air is confined by the tunnel walls to move along the tunnel. Behind the moving vehicle, as air has been pushed away, suction is created, and air is pulled to flow into the tunnel. In addition, because of fluid viscosity , the surface of the vehicle drags the air to flow with vehicle, a force experienced as skin drag by the vehicle. This movement of air by the vehicle is analogous to the operation of a mechanical piston as inside a reciprocating compressor gas pump, hence the name "piston effect". The effect is also similar to the pressure fluctuations inside drainage pipes as waste water pushes air in front of it.
The piston effect is very pronounced in railway tunnels, because the cross sectional area of trains is large and in many cases almost completely fills the tunnel cross section . The wind felt by the passengers on underground railway platforms (that do not have platform screen doors installed) when a train is approaching is air flow from the piston effect. The effect is less pronounced in road vehicle tunnels, as the cross-sectional area of vehicle is small compared to the total cross-sectional area of the tunnel. Single track tunnels experience the maximum effect but clearance between rolling stock and the tunnel as well as the shape of the front of the train affect its strength. [ 3 ]
Air flow caused by the piston effect can exert large forces on the installations inside the tunnel and so these installations have to be carefully designed and installed properly. Non-return dampers are sometimes needed to prevent stalling of ventilation fans caused by this air flow. [ 3 ]
The piston effect has to be considered by building designers in relation to smoke movement within an elevator shaft. [ 4 ] A moving elevator car forces the air in front of it out of the shaft and pulls air into the shaft behind it with the effect most apparent in elevator systems with a fast moving car in a single shaft. This means that in a fire a moving elevator may push smoke into lower floors. [ 4 ]
The piston effect is used in tunnel ventilation. In railway tunnels, the train pushes out the air in front of it toward the closest ventilation shaft in front, and sucks air into the tunnel from the closest ventilation shaft behind it. The piston effect can also assist ventilation in road vehicle tunnels.
In underground rapid transit systems, the piston effect contributes to ventilation and in some cases provides enough air movement to make mechanical ventilation unnecessary. At wider stations with multiple tracks, air quality remains the same and can even improve when mechanical ventilation is disabled. At narrow platforms with a single tunnel, however, air quality worsens when relying on the piston effect alone for ventilation. This still allows for potential energy savings by taking advantage of the piston effect rather than mechanical ventilation where possible. [ 5 ]
Tunnel boom is a loud boom sometimes generated by high-speed trains when they exit tunnels. These shock waves can disturb nearby residents and damage trains and nearby structures. People perceive this sound similarly to that of a sonic boom from supersonic aircraft. However, unlike a sonic boom, tunnel boom is not caused by trains exceeding the speed of sound. Instead, tunnel boom results from the structure of the tunnel preventing the air around the train from escaping in all directions. As a train passes through a tunnel, it creates compression waves in front of it. These waves coalesce into a shock wave that generates a loud boom when it reaches the tunnel exit. [ 6 ] [ 7 ] The strength of this wave is proportional to the cube of the train's speed, so the effect is much more pronounced with faster trains. [ 7 ]
Tunnel boom can disturb residents near the mouths of tunnels, and it is exacerbated in mountain valleys where the sound echoes. Reducing these disturbances is a significant challenge for high-speed lines such as Japan's Shinkansen , France's TGV and Spain's AVE . Tunnel boom has become a principal limitation to increased train speeds in Japan where the mountainous terrain requires frequent tunnels. Japan has enacted a law limiting noise to 70 dB in residential areas, [ 8 ] which include many tunnel exit zones.
Methods of reducing tunnel boom include making the train's profile highly aerodynamic , adding hoods to tunnel entrances, [ 9 ] installing perforated walls at tunnel exits, [ 6 ] and drilling vent holes in the tunnel [ 7 ] (similar to fitting a silencer on a firearm, but on a far bigger scale). The HS2 project in the United Kingdom has developed "porous portal" tunnel hoods to mitigate tunnel boom for residents, as well as minimising aural discomfort for passengers that could arise from in-train air pressure changes. [ 10 ] [ 11 ] [ 12 ]
Passengers and crew may experience ear discomfort as a train enters a tunnel because of rapid pressure changes. [ 13 ] | https://en.wikipedia.org/wiki/Piston_effect |
The reciprocating motion of a non-offset piston connected to a rotating crank through a connecting rod (as would be found in internal combustion engines ) can be expressed by equations of motion . This article shows how these equations of motion can be derived using calculus as functions of angle ( angle domain ) and of time ( time domain ) .
The geometry of the system consisting of the piston, rod and crank is represented as shown in the following diagram:
From the geometry shown in the diagram above, the following variables are defined:
The following variables are also defined:
The frequency ( Hz ) of the crankshaft 's rotation is related to the engine's speed ( revolutions per minute ) as follows:
So the angular velocity ( radians /s) of the crankshaft is:
As shown in the diagram, the crank pin , crank center and piston pin form triangle NOP. By the cosine law it is seen that:
where l {\displaystyle l} and r {\displaystyle r} are constant and x {\displaystyle x} varies as A {\displaystyle A} changes.
Angle domain equations are expressed as functions of angle.
The angle domain equations of the piston's reciprocating motion are derived from the system's geometry equations as follows.
Position with respect to crank angle (from the triangle relation, completing the square , utilizing the Pythagorean identity , and rearranging):
Velocity with respect to crank angle (take first derivative , using the chain rule ):
Acceleration with respect to crank angle (take second derivative , using the chain rule and the quotient rule ):
The angle domain equations above show that the motion of the piston (connected to rod and crank) is not simple harmonic motion , but is modified by the motion of the rod as it swings with the rotation of the crank. This is in contrast to the Scotch Yoke which directly produces simple harmonic motion.
Example graphs of the angle domain equations are shown below.
Time domain equations are expressed as functions of time.
Angle is related to time by angular velocity ω {\displaystyle \omega } as follows:
If angular velocity ω {\displaystyle \omega } is constant, then:
and:
The time domain equations of the piston's reciprocating motion are derived from the angle domain equations as follows.
Position with respect to time is simply:
Velocity with respect to time (using the chain rule ):
Acceleration with respect to time (using the chain rule and product rule , and the angular velocity derivatives ):
From the foregoing, you can see that the time domain equations are simply scaled forms of the angle domain equations: x {\displaystyle x} is unscaled, x ′ {\displaystyle x'} is scaled by ω , and x ″ {\displaystyle x''} is scaled by ω² .
To convert the angle domain equations to time domain, first replace A with ωt , and then scale for angular velocity as follows: multiply x ′ {\displaystyle x'} by ω , and multiply x ″ {\displaystyle x''} by ω² .
By definition, the velocity maxima and minima occur at the acceleration zeros (crossings of the horizontal axis) .
The velocity maxima and minima (see the acceleration zero crossings in the graphs below) depend on rod length l {\displaystyle l} and half stroke r {\displaystyle r} and do not occur when the crank angle A {\displaystyle A} is right angled.
The velocity maxima and minima do not necessarily occur when the crank makes a right angle with the rod. Counter-examples exist to disprove the statement "velocity maxima and minima only occur when the crank-rod angle is right angled" .
For rod length 6" and crank radius 2" (as shown in the example graph below), numerically solving the acceleration zero-crossings finds the velocity maxima/minima to be at crank angles of ±73.17530°. Then, using the triangle law of sines , it is found that the rod-vertical angle is 18.60639° and the crank-rod angle is 88.21832°. Clearly, in this example, the angle between the crank and the rod is not a right angle. Summing the angles of the triangle 88.21832° + 18.60639° + 73.17530° gives 180.00000°. A single counter-example is sufficient to disprove the statement "velocity maxima/minima occur when crank makes a right angle with rod" .
The graphs below show the angle domain equations for a constant rod length l {\displaystyle l} (6.0") and various values of half stroke r {\displaystyle r} (1.8", 2.0", 2.2"). Note in the graphs that L is rod length l {\displaystyle l} and R is half stroke r {\displaystyle r} .
Below is an animation of the piston motion equations with the same values of rod length and crank radius as in the graphs above.
Note that for the automotive / hotrod use-case the most convenient (used by enthusiasts) unit of length for the piston-rod-crank geometry is the inch , with typical dimensions being 6" (inch) rod length and 2" (inch) crank radius. This article uses units of inch (") for position, velocity and acceleration, as shown in the graphs above. | https://en.wikipedia.org/wiki/Piston_motion_equations |
Pisuviricota is a phylum of RNA viruses that includes all positive-strand and double-stranded RNA viruses that infect eukaryotes and are not members of the phylum Kitrinoviricota , Lenarviricota or Duplornaviricota . [ 1 ] The name of the group is a syllabic abbreviation of “ pi cornavirus su pergroup” with the suffix -viricota , indicating a virus phylum . [ 2 ] Phylogenetic analyses suggest that Birnaviridae and Permutotetraviridae , both currently unassigned to a phylum in Orthornavirae , also belong to this phylum and that both are sister groups. [ 3 ] Another proposed family of the phylum is unassigned Polymycoviridae in Riboviria . [ 4 ]
The phylum contains the following classes: [ 1 ]
Additionally, the following taxa in Pisuviricota are unassigned to higher taxa: [ 1 ]
This virus -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pisuviricota |
Pits are relatively thinner portions of the cell wall that adjacent cells can communicate or exchange fluid through. Pits are characteristic of cell walls with secondary layers . Generally each pit has a complementary pit opposite of it in the neighboring cell. These complementary pits are called "pit pairs". [ 1 ]
Pits are composed of three parts: the pit chamber, the pit aperture, and the pit membrane. The pit chamber is the hollow area where the secondary layers of the cell wall are absent. The pit aperture is the opening at either end of the pit chamber. The pit membrane is the primary cell wall and middle lamella , or the membrane between adjacent cell walls, at the middle of the pit chamber. [ 2 ]
The primary cell wall at the pit membrane may also have depressions similar to the pit depressions of the secondary layers. These depressions are primary pit-fields, or primary pits. In the primary pit, the primordial pit provides an interruption in the primary cell wall that the plasmodesmata can cross. The primordial pit is the only aperture in the otherwise continuous primary cell wall. [ 3 ]
Pit pairs are a characteristic feature of xylem , as sap flows through the pits of xylem cells. [ 4 ]
Though pits are usually simple and complementary, a few more pit variations can be formed: [ 5 ] [ 6 ]
Plasmodesmata are thin sections of the endoplasmic reticulum that traverse pits and connect adjacent cells. These sections provide an avenue of transport through the pits and facilitate communication. [ 8 ] Plasmodesmata are not restricted to pits however, as plasmodesmata often cross a cell wall of constant width and occasionally the cell wall is even wider in areas where plasmodesmata traverse it. [ 3 ]
The torus and margo are characteristic features of bordered pit-pairs in gymnosperms , such as Coniferales , Ginkgo , and Gnetales . In other vascular plants , the torus is rare. The pit membrane is separated into two parts: a thick impermeable torus at the center of the pit membrane, and the permeable margo surrounding it. The torus regulates the functions of the bordered pit, and the margo is a cell wall-derived porous membrane that supports the torus. The margo is composed of bundles of microfibrils that radiate from the torus. [ 3 ]
The margo is flexible and can move towards either side of the pit while under stress. This allows the thick, impermeable torus to block the pit aperture. When the torus is displaced so that it blocks the pit aperture, the pit is said to be aspirated. [ 9 ] | https://en.wikipedia.org/wiki/Pit_(botany) |
The pit sword (also known as a rodmeter) is a blade of metal or plastic that extends into the water beneath the hull of a ship . [ 1 ] It is part of the pitometer log , a device for measuring the ship's speed through the water. | https://en.wikipedia.org/wiki/Pit_sword |
Pit water , mine water or mining water is water that collects in a mine and which has to be brought to the surface by water management methods in order to enable the mine to continue working.
Although all water that enters pit workings originates from atmospheric precipitation , the miner distinguishes between surface water and groundwater . Surface water enters the pit through openings in the mine at the surface of the ground, such as tunnel portals or shaft entrances. During heavy rain, water seeps into the earth and forms ground water when it meets layers of impervious rock. Pit water is mainly interstitial water and groundwater that seeps into the mine workings . [ 1 ]
This geochemistry article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pit_water |
PitchCom is a wireless communication system used in baseball that lets a player request pitches without using visible signals . Major League Baseball (MLB) approved the use of PitchCom before the start of the 2022 season with the intentions of deterring sign stealing and quickening the pace of play . [ 1 ]
Catchers traditionally request pitches with finger signs, but these can be stolen by a runner on second base and relayed to the batter. When a runner reaches second base, the catcher commonly visits the pitcher to change signs, delaying the game.
The technology used in PitchCom was invented by John Hankins and Craig Filcetti to provide cues at magic shows . [ 2 ] Their company asked MLB to consider adopting the technology in 2020. [ 1 ] During the 2021 Low-A West season, teams were permitted to try PitchCom. The technology was optional but strongly encouraged, according to a memo sent by the league. [ 3 ] After generally positive results in the minor league, and in spring training before the 2022 MLB season, the MLB Players Association approved use of PitchCom for the 2022 season. [ 1 ]
During spring training before the 2023 MLB season , MLB allowed pitchers to wear PitchCom wristbands so they could call their own pitches. [ 4 ] As spring training ended, MLB allowed pitchers to request pitches on PitchCom during the 2023 regular season. [ 5 ] MLB also clarified its rules, stating that in the event of a PitchCom malfunction, a pitcher or catcher must immediately notify an umpire, who would grant a timeout if the player is not attempting to circumvent pace of play rules. [ 6 ]
The KBO League began using PitchCom in July 2024. [ 7 ]
PitchCom has two functional components: a nine-button keypad that the catcher wears and small wireless receivers, with speakers, that the catcher, the pitcher, and up to three other fielders may wear inside their baseball caps . [ 8 ] Each receiver can be programmed to a particular spoken language . When the catcher presses buttons to indicate the type of pitch and the desired location, all receivers speak the instructions in the selected language. All communications are encrypted , and teams may opt to replace pitch names such as "fastball" with code words . [ 1 ]
During its first season of use in MLB, some players had problems using PitchCom. Early in the 2022 season, New York Yankees pitcher Aroldis Chapman had difficulty hearing PitchCom over the crowd during an appearance at Oriole Park at Camden Yards . "We just might have to turn up our volume a little bit," said Jose Trevino , the Yankees' catcher. Gerrit Cole , another Yankees pitcher, had trouble hearing pitch instructions in his first two starts, including an incident where the instructions were drowned out by a siren sound effect that the Yankee Stadium audio crew plays to energize the crowd. [ 9 ] During a game on June 30 against the Houston Astros , Yankees pitcher Luis Severino was trying to fix his malfunctioning PitchCom device when Kyle Tucker , on third base, tried to steal home . Severino, despite the distraction, threw out Tucker at home. [ 10 ] On Opening Day , Milwaukee Brewers pitcher Corbin Burnes had problems hearing his PitchCom speaker over the crowd noise at American Family Field . [ 11 ]
During the 2022 season, in response to complaints, PitchCom was modified to have a higher volume limit and to have an extension tube that put sound closer to the player's ear. Even at the higher maximum volume, during the 2022 MLB postseason , Philadelphia Phillies shortstop Bryson Stott struggled to hear the audio over the crowd noise. [ 12 ] During a spring training game before the 2023 season, umpires informed Minnesota Twins manager Rocco Baldelli that umpires and Tampa Bay Rays batters could clearly hear PitchCom signals because Twins catcher Tony Wolters had his speaker volume turned up to an excessively high level and because the announced crowd of 2,531 at Tropicana Field was quiet. [ 13 ]
Despite early problems, all 30 MLB clubs started to use PitchCom in some way during the 2022 season. [ 14 ] Detroit Tigers catcher Tucker Barnhart said that the technology would make the Tigers ready for the pitch clock when MLB starts to use it. [ 15 ] Cleveland Guardians manager Terry Francona and catcher Austin Hedges said that the system sped up games noticeably. [ 16 ] Yankees manager Aaron Boone credited PitchCom with significantly shortening Yankees games in 2022. Through their first 54 games in 2022, the Yankees played 25 games (almost half) in less than three hours each. In 2021, only about one quarter of the Yankees' games finished in three hours or less. [ 17 ] Across the majors, the average time of a nine-inning game in 2022 decreased by six minutes from the prior season, which ESPN credited in part to PitchCom. [ 18 ]
New York Mets pitcher Max Scherzer used PitchCom for the first time on July 27, 2022. He praised PitchCom's functionality, but he told reporters that "it should be illegal," saying that it removes incentives for pitchers to create complex visual sign systems that runners are challenged to decode. "It works," he said, "but it’s taking away a part of the game." [ 19 ] Scherzer's comments drew rebuttals from Seattle Mariners relief pitcher Paul Sewald , who called them "a little naïve" and "a bit hypocritical," and from Minnesota Twins starter Sonny Gray , who said that teams were able to break down sign sequences during a game. [ 14 ] | https://en.wikipedia.org/wiki/PitchCom |
Pitch is a viscoelastic polymer which can be natural or manufactured, derived from petroleum , coal tar , [ 1 ] or plants. Pitch produced from petroleum may be called bitumen or asphalt , while plant-derived pitch, a resin , is known as rosin in its solid form. Tar is sometimes used interchangeably with pitch, but generally refers to a more liquid substance derived from coal production, including coal tar , or from plants, as in pine tar . [ 2 ]
Pitch, a traditional naval store , was traditionally used to help caulk the seams of wooden sailing vessels (see shipbuilding ). Other important historic uses included coating earthenware vessels for the preservation of wine, waterproofing wooden containers, and making torches . It was also used to make patent fuel from coal slack around the turn of the 19th century. [ 3 ] Petroleum-derived pitch is black in colour, hence the adjectival phrase "pitch-black". [ 4 ]
The viscoelastic properties of pitch make it well suited for the polishing of high-quality optical lenses and mirrors. In use, the pitch is formed into a lap or polishing surface, which is charged with iron oxide ( Jewelers' rouge ) or cerium oxide. The surface to be polished is pressed into the pitch, then rubbed against the surface so formed. The ability of pitch to flow, albeit slowly, keeps it in constant uniform contact with the optical surface.
Chasers pitch is a combination of pitch and other substances, used in jewelry making.
Naturally occurring asphalt /bitumen, a type of pitch, is a viscoelastic polymer . This means that even though it seems to be solid at room temperature and can be shattered with a hard impact, it is actually fluid and will flow over time, but extremely slowly. The pitch drop experiment taking place at University of Queensland is a long-term experiment which demonstrates the flow of a piece of pitch over many years. For the experiment, pitch was put in a glass funnel and allowed to slowly drip out. Since the pitch was allowed to start dripping in 1930, only nine drops have fallen. It was calculated in the 1980s that the pitch in the experiment has a viscosity approximately 100 billion (10 11 ) times that of water. [ 5 ] The eighth drop fell on 28 November 2000, and the ninth drop fell on 17 April 2014. [ 6 ] Another experiment was started by a colleague of Nobel Prize winner Ernest Walton in the physics department of Trinity College in Ireland in 1944. Over the years, the pitch had produced several drops, but none had been recorded. On July 11, 2013, scientists at Trinity College caught pitch dripping from a funnel on camera for the first time. [ 7 ]
The heating ( dry distilling ) of wood causes tar and pitch to drip away from the wood and leave behind charcoal . Birchbark is used to make birch-tar , a particularly fine tar. The terms tar and pitch are often used interchangeably. However, pitch is considered more solid, while tar is more liquid. Traditionally, pitch that was used for waterproofing buckets, barrels and ships was drawn from pine . It is used to make cutler's resin .
A 10th-century redaction of an earlier Greek Byzantine agricultural work brings down the ancient method of applying pitch to ceramic wine jars such as amphorae or pithoi :
[A wood-based pitch] [ note 1 ] is put into an earthen vessel, and it is put over a small fire in the sun, then some hot water percolated through wood-ashes is poured on it, and the pitch is stirred; when it has afterward stood, it is poured out after two hours, then there is as much water again poured in. Having therefore done this thrice every day for three days and having taken up the moisture on the surface, they make the pitch that is left exceedingly good. Dry pitch is also bitter, but being boiled with wine it becomes more useful; [...] and having boiled the mixture to a third part, they use it as properly qualified: but some throw wood-ashes into it and boil it down. In Italy they use pitch of this kind: forty minæ [ note 2 ] of pitch, one of wax , eight drams [ note 3 ] of sal ammoniac , six drams of manna. [ note 4 ] Thus, having pounded them and boiled them together, they sprinkle eight ounces ( uncia ) [ note 5 ] of well-ground fenugreek over them and they pitch the cask with them when they are well mixed. [ 8 ]
The ceramic ware was pitched, both inside and out, immediately when removed from the kiln and still hot. [ 9 ] | https://en.wikipedia.org/wiki/Pitch_(resin) |
A variable speed pitch control (or vari-speed ) is a control on an audio device such as a turntable , tape recorder , or CD player that allows the operator to deviate from a standard speed (such as 33, 45 or even 78 rpm on a turntable), resulting in adjustments in pitch. [ 1 ] The latter term "vari-speed" is more commonly used for tape decks, particularly in the UK . Analog pitch controls vary the voltage being used by the playback device; digital controls use digital signal processing to change the playback speed or pitch. A typical DJ deck allows the pitch to be increased or reduced by up to 8%, which is achieved by increasing or reducing the speed at which the platter rotates.
Turntable or CD playing speed may be changed for beatmatching and other DJ techniques, while pitch shift using a pitch control has myriad uses in sound recording .
Superscope, Inc. of Sun Valley added vari-speed as a feature of portable cassette decks in 1975. The C-104 and C-105 models incorporated this feature. [ 2 ] [ 3 ]
Superscope trademarked the name Vari-Speed in 1974. The trademark category was Computer & Software Products & Electrical & Scientific Products. The trademark goods and Services use was Magnetic tape recorders and reproducers . The trademark expired in 1995. [ 4 ] [ 5 ]
Pitch control is fundamental for DJing . By changing pitch, a DJ can alter the speed of an upcoming track to match its tempo to that of the currently playing track so that the beats are synchronized, a technique called beatmatching . Through beatmatching, a DJ can create smooth transitions between tracks in a DJ set .
Turntables, CDJs , DJ controllers , and DJ software allow DJs to change the speed at which a track is played for this purpose. Technics SL-1200 turntables allow pitch changes to +/− 8% or 16%, depending on the model, and modern DJ gear often allows a range of +/- 100% (from pausing the track to playing the track twice as fast).
Modern DJ equipment also features time stretching , which allows the speed of a track to be changed without affecting its pitch, a feature often called "Master Tempo" or "Key Lock". Some equipment also features pitch shifting , allowing pitch to be adjusted independently of tempo; this allows changing the musical key of tracks so that transitions between them sound more pleasing to the listener, a practice called harmonic mixing .
On Technics SL-1200 turntables, pressing the Reset button returns the pitch to a fixed preset value of +/−0% regardless of the pitch control position. [ 6 ] [ 7 ] | https://en.wikipedia.org/wiki/Pitch_control |
Pitch correction is an electronic effects unit or audio software that changes the intonation (highness or lowness in pitch) of an audio signal so that all pitches will be notes from the equally tempered system (i.e., like the pitches on a piano ). Pitch correction devices do this without affecting other aspects of its sound. Pitch correction first detects the pitch of an audio signal (using a live pitch detection algorithm ), then calculates the desired change and modifies the audio signal accordingly. The widest use of pitch corrector devices is in Western popular music on vocal lines .
Prior to the invention of pitch correction, errors in vocal intonation in recordings could only be corrected by re-recording the entire song (in the early era of recording) or, after the development of multitrack recording , by overdubbing the incorrect vocal pitches by re-recording those specific notes or sections. By the late 70s, engineers were fixing parts using the Eventide Harmonizer . Prior to the development of electronic pitch correction devices, there was no way to make " real time " corrections to a live vocal performance in a concert (although lip-syncing was used in some cases where a performer was not able to sing adequately in live performances).
Pitch correction was relatively uncommon before 1997 when Antares Audio Technology's Auto-Tune Pitch Correcting Plug-In was introduced. Developed by Dr. Andy Hildebrand, a geophysical engineer , the software leveraged auto-correlation algorithms originally used in seismic wave mapping for the oil industry . Andy Hildebrand adapted these algorithms for musical applications, offering a more efficient and precise way to correct vocal imperfections. This replaced slow studio techniques with a real-time process that could also be used in live performances. [ 1 ] [ 2 ]
Auto-Tune is still widely used, as are other pitch-correction algorithms including Celemony's Direct Note Access which allows adjustment of individual notes in a polyphonic audio signal, [ 3 ] and Celemony's Melodyne . Pitch correction is now a common feature in digital audio editing software, having first appeared as a Pro Tools plugin and now being found in products such as Apple GarageBand , Apple Logic Pro , Adobe Audition , FL Studio , Digital Performer , and Steinberg Cubase . MorphTune also provides this functionality. It is also available in the form of rackmount hardware, such as the TC-Helicon VoiceOne. There is also a large stompbox pedal that provides pitch correction in a small device that could be used at a show by plugging the vocal microphone into the pedal and then sending the signal to the PA system . A free VST plugin known as GSnap can also be used to get the same effect. In the Linux FOSS community, Autotalent and Zita-AT1 offer this functionality.
The most common use of pitch correctors is to fix wrong intonation (tuning) of notes sung by vocalists in popular music sound recordings. The use of pitch correction speeds up the recording process, because singers do not need to keep singing a song or vocal line and re-recording it until the pitches are correct. The pitch correction software can correct any pitch errors in the singing without the need for overdubbing or re-recording.
While pitch correction is most associated with fixing vocal intonation errors, it can also be used to fix intonation in recorded instrumental parts such as violin, cello or trumpet.
Pitch correctors are commonly used in music studios to add the sound of vocal harmony to certain sung words or phrases without re-recording those lines again at the necessary pitches or using backup singers . Depending on the model used, various vocal effects can be added and the better quality devices can be adjusted to allow expression to remain in the music. Some pitch correctors can add vibrato .
While pitch correction devices were initially designed to produce natural-sounding effects, producers discovered that by setting extreme parameter values, unusual effects could be obtained. Pitch correction devices became popular in the late 1990s as a distinctively electronic, vocoder -like voice effect. A notable example of Auto-Tune -based pitch correction is the Cher effect , so named because producer Mark Taylor originated the effect in her 1998 hit song " Believe ". [ 4 ] The effect has been used by composer John Boswell for his Symphony of Science and Symphony of Bang Goes The Theory (a BBC science show) mash-ups. American Rapper T-Pain is known for his skillful use of this effect.
One criticism of pitch correction is that it allows recording engineers to create a perfectly in-tune performance from a vocalist who is otherwise not skilled enough to give one, adding a degree of dishonesty to music. [ 5 ] This concept was featured in a 2001 episode of The Simpsons , entitled " New Kids on the Blecch ". In the episode, a cartoon representation of a pitch corrector (labeled "Studio Magic") was used to make up for the total lack of singing talent in a manufactured boy band , of which Bart Simpson was a member.
In 2003, Allison Moorer began attaching stickers to her 2002 album Miss Fortune reading "Absolutely no vocal tuning or pitch-correction was used in the making of this record." [ 6 ]
A Chicago Tribune report from 2003 stated that "many successful mainstream artists in most genres of music—perhaps a majority of artists—are using pitch correction". [ 7 ] Timothy Powell, a producer/engineer, stated in 2003 that he is "even starting to see vocal tuning devices show up in concert settings"; he states that "That's more of an ethical dilemma—people pay a premium dollar to see artists and artists want people to see them at their best." [ 7 ]
In 2010, producer Teddy Riley claimed that the processing of Michael Jackson 's voice with Melodyne caused fans to question the authenticity of the voice on the posthumous album Michael . [ 8 ] Riley claimed that because he did not have a "final vocal" from Jackson, Melodyne had to be used "to make his voice work with the actual music," "to get him in key" and this resulted in the vibrato sounding "a little off" or "over-processed." [ 8 ] | https://en.wikipedia.org/wiki/Pitch_correction |
Pitch drop-back is the phenomena by which an aircraft which is perturbed in flight path angle from its trim position by a step input exhibits an output which is indicative of a second order system. [ 1 ]
A pilot who actuates an elevator input may find that the aircraft then "droops" or "drops back" to a position further toward the start position. The phenomenon is particularly marked in tilt-rotor aircraft. [ 2 ] Pitch drop-back may be controlled using a Stability Augmentation System or Stability Control and Augmentation System. [ 3 ]
This article about transport is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Pitch_drop-back |
A pitch drop experiment is a long-term experiment which measures the flow of a piece of pitch over many years. "Pitch" is the name for any of a number of highly viscous liquids which appear solid, most commonly bitumen , also known as asphalt. At room temperature, tar pitch flows at a very low rate, taking several years to form a single drop.
The best-known version [ 1 ] of the experiment was started in 1927 by Thomas Parnell of the University of Queensland in Brisbane , Australia, to demonstrate to students that some substances which appear solid are highly viscous fluids. [ 2 ] Parnell poured a heated sample of the pitch into a sealed funnel and allowed it to settle for three years. [ 3 ] In 1930, the seal at the neck of the funnel was cut, allowing the pitch to start flowing. A glass dome covers the funnel and it is placed on display outside a lecture theatre. [ 4 ] Each droplet forms and falls over a period of about a decade .
Between 1961 and 2013, the experiment was supervised by John Mainstone [ de ] .
The seventh drop fell at approximately 4:45 p.m. on 3 July 1988, while the experiment was on display at Brisbane's World Expo 88 . However, apparently no one witnessed the drop fall itself; [ 5 ] Mainstone had stepped out to get a drink at the moment it occurred. [ 1 ]
The eighth drop fell on 28 November 2000, allowing experimenters to calculate the pitch as having a viscosity of approximately 230 billion times that of water . [ 6 ]
This experiment is recorded in Guinness World Records as the "world's longest continuously running laboratory experiment", [ 7 ] and it is expected there is enough pitch in the funnel to allow it to continue for at least another hundred years. This experiment is predated by two other (still-active) scientific devices, the Oxford Electric Bell (1840) and the Beverly Clock (1864), but each of these has experienced brief interruptions since 1937.
The experiment was not originally carried out under any special controlled atmospheric conditions, meaning the viscosity could vary throughout the year with fluctuations in temperature . Sometime after the seventh drop fell (1988), air conditioning was added to the location where the experiment takes place. The lower average temperature has lengthened each drop's stretch before it separates from the rest of the pitch in the funnel, and correspondingly the typical interval between drops has increased from eight years to 12–13 years.
In October 2005, Mainstone and Parnell were awarded the Ig Nobel Prize in physics, a parody of the Nobel Prize , for the pitch drop experiment. [ 8 ] Mainstone subsequently commented:
I am sure that Thomas Parnell would have been flattered to know that Mark Henderson considers him worthy to become a recipient of an Ig Nobel prize. Professor Parnell's award citation would of course have to applaud the new record he had thereby established for the longest lead-time between the performance of a seminal scientific experiment and the conferral of such an award, be it a Nobel or an Ig Nobel prize. [ 9 ]
The experiment is monitored by a webcam [ 10 ] but technical problems prevented the November 2000 drop from being recorded. [ 7 ] The pitch drop experiment is on public display on Level 2 of Parnell building in the School of Mathematics and Physics at the St Lucia campus of the University of Queensland . Hundreds of thousands of Internet users check the live stream each year. [ 4 ]
John Mainstone died on 13 August 2013, aged 78, following a stroke . [ 11 ] Custodianship then passed to Andrew White. [ 12 ]
The ninth drop touched the eighth drop on 12 April 2014; [ 13 ] [ 14 ] [ 15 ] however, it was still attached to the funnel. On 24 April, Professor White decided to replace the beaker holding the previous eight drops before the ninth drop fused to them (which would have permanently affected the ability of further drops to form). While the bell jar was being lifted, the wooden base wobbled and the ninth drop snapped away from the funnel. [ 16 ]
Timeline for the University of Queensland experiment:
The pitch drop experiment at Trinity College Dublin in Ireland was started in October 1944 by an unknown colleague of the Nobel Prize winner Ernest Walton while he was in the physics department of Trinity College. This experiment, like the one at University of Queensland, was set up to demonstrate the high viscosity of pitch. This physics experiment sat on a shelf in a lecture hall at Trinity College unmonitored for decades as it dripped a number of times from the funnel to the receiving jar below, also gathering layers of dust. [ 17 ] [ 18 ] [ 19 ]
In April 2013, about a decade after the previous pitch drop, physicists at Trinity College noticed that another drip was forming. They moved the experiment to a table to monitor and record the falling drip with a webcam, allowing all present to watch. The pitch dripped around 17:00 IST on 11 July 2013, marking the first time that a pitch drop was successfully recorded on camera.
Based on the results from this experiment, the Trinity College physicists estimated that the viscosity of the pitch is about two million times that of honey, or about 20 billion times the viscosity of water. [ 17 ]
A pitch drop experiment was begun at the University of St Andrews in 1927, the same year as the Queensland experiment. No evidence has emerged of any contact between Parnell and the instigator or instigators of the St. Andrews experiment. The pitch in the St. Andrews experiment flows in a largely steady, but extremely slow, stream. [ 20 ] At some stage (likely in 1984) St. Andrews professor John Allen modified the St. Andrews experiment to bring its setup closer to that of the University of Queensland experiment. [ 21 ]
In 2014, media reported that a pitch drop experiment had been recently rediscovered at Aberystwyth University in Wales. Dating from 1914, it predates the Queensland experiment by 13 years. But as the pitch is more viscous (or the average temperature lower) this experiment has not yet produced its first drop and is not expected to for over 1,000 years. [ 1 ] [ 22 ]
Another pitch-in-funnel demonstration was begun in 1902 by the Royal Scottish Museum in Edinburgh and is in Edinburgh at the Royal Scottish Museum's successor institution the National Museum of Scotland . [ 23 ] The known records of its behaviour are incomplete: it is known to have dripped once at some time between 4 and 6 June 2016 and on at least one occasion in the past, but the time and number of the previous drip or drips is unknown. Furthermore, the June 2016 drip happened shortly after the experiment was taken out of museum storage, and the physical movement may have caused it to drip at that time. [ 24 ]
In the Hunterian Museum at the University of Glasgow are two pitch-based demonstrations by Lord Kelvin from the 19th century. Kelvin placed some bullets on top of a dish of pitch, and corks at the bottom: over time, the bullets sank and the corks floated.
Lord Kelvin also showed that the pitch flows like glaciers , with a mahogany ramp that allowed it to slide slowly downward and form shapes and patterns similar to glaciers in the Alps . [ 1 ] This model was considered as an inspiration for the expected properties of luminiferous aether . [ 25 ] [ 26 ] | https://en.wikipedia.org/wiki/Pitch_drop_experiment |
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