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17,569,235 | https://en.wikipedia.org/wiki/Lists%20of%20rail%20accidents | This is the list of rail accident lists.
Lists
By year
By type
By country
By death toll
Terrorist incidents
See also
Classification of railway accidents
Derailment
Rail transport
Train wreck
Tram accident
Train-pedestrian fatalities | Lists of rail accidents | [
"Technology"
] | 42 | [
"Railway accidents and incidents",
"Lists of railway accidents and incidents"
] |
17,571,813 | https://en.wikipedia.org/wiki/Flora%20and%20fauna%20of%20Greenland | Although the bulk of its area is covered by ice caps inhospitable to most forms of life, Greenland's terrain and waters support a wide variety of plant and animal species. The northeastern part of the island is the world's largest national park. The flora and fauna of Greenland are strongly susceptible to changes associated with climate change.
The image galleries below link to information related to the flora and fauna of Greenland, including Latin taxonomy, Danish translations, and links to articles in the Danish Wikipedia, which can be helpful when searching for more information.
Flora
310 species of vascular plants were said to be found in Greenland in 2019, including 15 endemic species. Although individual plants can be profuse in favourable situations, relatively few plant species tend to be represented in a given place.
In northern Greenland, the ground is covered with a carpet of mosses and low-lying shrubs such as dwarf willows and crowberries. Flowering plants in the north include yellow poppy, Pedicularis, and Pyrola. Plant life in southern Greenland is more abundant, and certain plants, such as the dwarf birch and willow, may grow several feet high.
The only natural forest in Greenland is found in the Qinngua Valley. The forest consists mainly of downy birch (Betula pubescens) and grey-leaf willow (Salix glauca), growing up to tall, although nine stands of conifers had been cultivated elsewhere by 2007.
Horticulture shows a certain degree of success. Plants such as broccoli, radishes, spinach, leeks, lettuce, turnips, chervil, potatoes and parsley are grown up to considerable latitudes, while the very south of the country also rears asters, Nemophila, mignonette, rhubarb, sorrel and carrots. Over the decade to 2007, the growing season lengthened by as much as three weeks.
In the 13th-century Konungs skuggsjá (King's mirror), it is stated that the old Norsemen tried in vain to raise barley. Recent research from archaeological digs on Greenland by the National Museum in Copenhagen discovered barley grains and concluded that the Vikings were able to grow barley.
Fauna
Land mammals
Among the large land mammals are the musk ox, the reindeer, the polar bear and the white Arctic wolf. Other familiar mammals in Greenland include the Arctic hare, collared lemming, Beringian ermine and Arctic fox. Reindeer hunting is of considerable cultural importance to the people of Greenland.
Domesticated land mammals include dogs, which were introduced by the Inuit, as well as such European-introduced species as goats, Greenlandic sheep, oxen and pigs, which are raised in modest numbers in the south.
Marine mammals
As many as two million seals are estimated to inhabit Greenland's coasts; species include the hooded seal (Cystophora cristata) as well as the grey seal (Halichoerus grypus). Whales frequently pass very close to Greenlandic shores in the late summer and early autumn. Species represented include the beluga whale, blue whale, Greenland whale, fin whale, humpback whale, minke whale, narwhal, pilot whale, sperm whale. Whaling was formerly a major industry in Greenland; by the turn of the 20th century, however, the right whale population was so depleted that the industry was in deep decline. Walruses are to be found primarily in the north and east of the country; like narwhal, they have at times suffered from overhunting for their tusks.
Birds
As of 1911, 61 species of birds were known to breed in Greenland. Certain birds such as the eider duck, guillemot and ptarmigan are often hunted for food in the winter.
Fish
Of the many species of fish inhabiting Greenland's waters, several have been of economic importance, including cod, caplin, halibut, rockfish, nipisak (Cycloperteus lumpus) and sea trout. The Greenland shark is used for the oil in its liver, as well as fermented and eaten as hákarl, a local delicacy.
See also
Fauna
List of mammals of Nunavut
List of Nunavut birds
Flora
List of Canadian plants by family
References
01
01
Greenland
Biota of archipelagoes | Flora and fauna of Greenland | [
"Biology"
] | 891 | [
"Biota of archipelagoes",
"Biota by biogeographic realm"
] |
17,571,895 | https://en.wikipedia.org/wiki/Aerobiological%20engineering | Aerobiological engineering is the science of designing buildings and systems to control airborne pathogens and allergens in indoor environments. The most-common environments include commercial buildings, residences and hospitals. This field of study is important because controlled indoor climates generally tend to favor the survival and transmission of contagious human pathogens as well as certain kinds of fungi and bacteria.
Aerobiological engineering in healthcare facilities
Since healthcare facilities can house a number of different types of patients who potentially have weakened immune systems, aerobiological engineering is of significant importance to engineers of hospitals. The aerobiology that concerns designers of hospitals includes viruses, bacteria, fungi, and other microbiological products such as endotoxins, mycotoxins, and microbial volatile organic compounds (MVOC's). Bacteria and viruses, because of their small size, readily become airborne as bacterial aerosols . Even large-sized droplets can remain suspended in the air for long periods if upward velocity of air in closed spaces exceed particle's downward velocity as dictated by their negligible mass. Because of this, adequate precautions and mitigation techniques need to be taken with indoor air quality in hospitals dealing with infectious diseases.
Ventilation systems
At a minimum, ventilation systems provide dilution and removal of airborne contaminants, which in general leads to improved indoor air quality and happier occupants. If filters are checked and replaced as needed, they can form an integral component of an immune building system designed to prevent the spread of diseases by airborne routes. They can also be used for pressurization of areas within buildings to provide contamination control.
Biocontamination in ventilation systems
Ventilation systems can contribute to the microbial loading of indoor environment by drawing in microbes from outdoor air and by creating conditions for growth. When microbes land on a wet filter that has been collecting dust, they have the perfect medium on which to grow, and if they grow through the filter they have the potential to be aerosolized and carried throughout the building via the HVAC control system.
Dilution rates
Bacteria in hospitals can be aerosolized when sick patients cough and sneeze and because of the large number of germs produced it is necessary that the number of air changes per hour (ACH) remain high in treatment and operating rooms. The American Society of Heating, Refrigerating and Air-Conditioning Engineers typically recommends 12-25 ACH in treatment and operating rooms and 4-6 ACH in intensive-care rooms. For rooms containing tuberculosis patients, the Centers for Disease Control and Prevention recommends an ACH of 6 to 12, with exhaust air being sent through high-efficiency-particulate-air (HEPA) filters before being sent outside.
Pressurized isolation rooms
In order to keep patients safe, hospitals use a range of technologies to combat airborne pathogens. Isolation rooms can be designed to feature positive or negative air-pressure flows. Positive-pressure rooms are used when there are patients who are extremely susceptible to disease, such as HIV patients. For these patients, it is paramount to prevent the ingress of any microorganisms, including common fungi and bacteria that may be harmless to healthy people. These systems filter the air before delivery with a HEPA filter and then pump it into the isolation room at high pressure, which forces air from the isolation room out into the hallway. In a negative-pressure system, the focus is on keeping infectious diseases isolated by controlling the airflow and directing harmful aerosols away from health care workers and other occupied areas. Negative pressure isolation rooms keep contaminants and pathogens from reaching external areas. The most common application of these rooms in the health industry today is for isolating tuberculosis patients. To do this, the air is exhausted from the room at a rate greater than that at which it is being delivered. This makes it difficult for airborne disease to go from a contaminated area to a hospital hallway, because air is constantly being drawn into the room rather than escaping from it.
Air sterilization processes
The normal means for filtration in healthcare facilities is low-efficiency air filters outside the air-handling unit followed by the HEPA (High Efficiency Particulate Air) filters placed after the air-handling unit. To be HEPA-certified, filters must remove particles of 0.3 μm diameter, with at least a 99.97-percent efficiency. Air burners sterilize air that is leaving contaminated isolation rooms by heating it to for six seconds. Ultraviolet germicidal irradiation (UVGI) is another technique for special-purpose air sterilization. It is defined as electromagnetic radiation in the range of about 200 to 320 nm, that is used to destroy microorganisms. When HEPA filters are used in conjunction with UV sterilization tools, the results can be extremely effective. The filter will remove the bigger, hardier spores, and all that is left are the smaller microbes which are killed more efficiently by the high-intensity UV treatment.
See also
Human habitat
Human outpost (artificially created controlled human habitat)
Legionnaires Disease
Aerobiology
References
C.S. Cox The Aerobiological Pathway of Microorganisms. Chichester G.B.: John Wiley & Sons 27, p. 118-119.
Godish, Thad. Indoor Environmental Quality. Boca Raton, FL, USA: Lewis Publishers, 2001. p. 190.
Kowalski, Wladyslaw Jan. Aerobiological Engineering Handbook. Blacklick, OH, USA: McGraw-Hill Professional Publishing, 2005. p. 6, 185, 231, 260, 528, 530.
Biological engineering
Ventilation
Human habitats | Aerobiological engineering | [
"Engineering",
"Biology"
] | 1,141 | [
"Biological engineering"
] |
17,571,980 | https://en.wikipedia.org/wiki/Pharmacopoeia%20of%20the%20People%27s%20Republic%20of%20China | The Pharmacopoeia of the People's Republic of China (PPRC) or the Chinese Pharmacopoeia (ChP), compiled by the Pharmacopoeia Commission of the Ministry of Health of the People's Republic of China, is an official compendium of drugs, covering Traditional Chinese and western medicines, which includes information on the standards of purity, description, test, dosage, precaution, storage, and the strength for each drug.
It is recognized by the World Health Organization as the official pharmacopoeia of China.
Content
The ChP, as of its tenth (2015) edition, comes in 4 volumes for both the Chinese and the English versions:
Traditional Chinese Medicine,
Chemical Medicine,
Biological Preparations,
General rules and common inactive ingredients, ; new volume
The English version is collectively coded as . The 2015 ChP requires Good Manufacturing Practices for all ChP-compliant medications and in general uses INN for English names. The Chinese version arranges medicines in ascending stroke order, while the English translations do so in alphabetical order.
History
The 1997 English version consists of two volumes:
Volume 1 (Herbal medicine), 1997,
Volume 2 (Western medicine), 1997,
The 1997 Chinese version (in simplified Chinese) also consists of two volumes, but the English and Chinese versions are not direct translations of each other, as they are sorted differently as is in the current edition.
A third volume was added in the 2005 version. The English edition () describes itself as a "compendium of almost all traditional Chinese medicines and most western medicines and preparations. Information is given for each drug on standards of purity, description, test, dosage, precaution, storage and strength. Key features: A total of 2691 monographs: 992 for traditional Chinese medicines and 1699 for modern western drugs.
"Volume I contains monographs of Chinese material medica and pared slice, vegetable oil/fat and its extract, Chinese traditional patent medicines, single ingredient of Chinese crude drug preparations etc.;
Volume II deals with monographs of chemical drugs, antibiotics, biochemical preparations, Radiopharmaceuticals and excipients for pharmaceutical use;
Volume III contains biological products."
See also
British Pharmacopoeia
Chinese herbology
Chinese Medical Herbology and Pharmacology
European Pharmacopoeia
Pharmacopoeia
The International Pharmacopoeia
United States Pharmacopeia
References
External links
The Pharmacopoeia of the People's Republic of China, 2020 Version.
Pharmacopoeias | Pharmacopoeia of the People's Republic of China | [
"Chemistry"
] | 526 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
17,573,081 | https://en.wikipedia.org/wiki/Modal%20matrix | In linear algebra, the modal matrix is used in the diagonalization process involving eigenvalues and eigenvectors.
Specifically the modal matrix for the matrix is the n × n matrix formed with the eigenvectors of as columns in . It is utilized in the similarity transformation
where is an n × n diagonal matrix with the eigenvalues of on the main diagonal of and zeros elsewhere. The matrix is called the spectral matrix for . The eigenvalues must appear left to right, top to bottom in the same order as their corresponding eigenvectors are arranged left to right in .
Example
The matrix
has eigenvalues and corresponding eigenvectors
A diagonal matrix , similar to is
One possible choice for an invertible matrix such that is
Note that since eigenvectors themselves are not unique, and since the columns of both and may be interchanged, it follows that both and are not unique.
Generalized modal matrix
Let be an n × n matrix. A generalized modal matrix for is an n × n matrix whose columns, considered as vectors, form a canonical basis for and appear in according to the following rules:
All Jordan chains consisting of one vector (that is, one vector in length) appear in the first columns of .
All vectors of one chain appear together in adjacent columns of .
Each chain appears in in order of increasing rank (that is, the generalized eigenvector of rank 1 appears before the generalized eigenvector of rank 2 of the same chain, which appears before the generalized eigenvector of rank 3 of the same chain, etc.).
One can show that
where is a matrix in Jordan normal form. By premultiplying by , we obtain
Note that when computing these matrices, equation () is the easiest of the two equations to verify, since it does not require inverting a matrix.
Example
This example illustrates a generalized modal matrix with four Jordan chains. Unfortunately, it is a little difficult to construct an interesting example of low order.
The matrix
has a single eigenvalue with algebraic multiplicity . A canonical basis for will consist of one linearly independent generalized eigenvector of rank 3 (generalized eigenvector rank; see generalized eigenvector), two of rank 2 and four of rank 1; or equivalently, one chain of three vectors , one chain of two vectors , and two chains of one vector , .
An "almost diagonal" matrix in Jordan normal form, similar to is obtained as follows:
where is a generalized modal matrix for , the columns of are a canonical basis for , and . Note that since generalized eigenvectors themselves are not unique, and since some of the columns of both and may be interchanged, it follows that both and are not unique.
Notes
References
Matrices | Modal matrix | [
"Mathematics"
] | 576 | [
"Matrices (mathematics)",
"Mathematical objects"
] |
17,573,867 | https://en.wikipedia.org/wiki/General%20Electric%20LMS100 | The General Electric LMS100 is an aero derivative gas turbine produced by GE Distributed Power.
Design and development
The LMS100 PA produces approximately 100 MW at an efficiency of around 46% LHV in open cycle operation. It is currently the largest and most efficient aero-derivative gas turbine. It is able to produce full rated power in under 10 minutes.
The LMS100 comprises a low-pressure compressor, an intercooler, a supercore and a power turbine. The supercore (comprising a HP compressor, compressor rear frame, high-pressure turbine and intermediate pressure turbine) is a further development of the LM6000, which in turn was based on the CF6-80C2. The low-pressure compressor is from the 6FA industrial gas turbine.
The first LMS100 engine entered commercial operation in July 2006 and a second unit in 2008. Other operational LMS100 power stations are at Laredo, TX (USA), El Paso, TX (USA), Firebaugh, CA (USA), Waterbury, CT (USA), Santiago (Chile), Guemes (Argentina) YPF Anello (2) (Argentina), Loma Campana, (2) Neuquen (Argentina), Edmonton (Canada), Calpine Corporation's Cumberland station in Millville, New Jersey, Stratford Power Station in New Zealand (opened in May 2011), Kwinana Power Station in Western Australia (opened in 2012), Dzhubginskaya, Russia (opened in 2013), and Tempe, AZ (5) (USA) (operational in 2019). LADWP (multiple sites, Long Beach (6), Playa Del Rey (2), City of Industry (5) ) Palm Springs (8), Otay Mesa (3) Excellon (2) Massachusetts
The LMS100 PA gas turbines utilize water injection for NOx control. The LMS100 PB gas turbine uses dry low NOx (DLE) combustors. The first LMS100 PB unit entered commercial operation in 2013.
See also
References
External links
GE introduced the LMS100 press release, GE Aviation
Aero-derivative engines
Gas turbines | General Electric LMS100 | [
"Technology"
] | 454 | [
"Aero-derivative engines",
"Engines",
"Gas turbines"
] |
17,574,685 | https://en.wikipedia.org/wiki/History%20of%20geophysics | The historical development of geophysics has been motivated by two factors. One of these is the research curiosity of humankind related to planet Earth and its several components, its events and its problems. The second is economical usage of Earth's resources (ore deposits, petroleum, water resources, etc.) and Earth-related hazards such as earthquakes, volcanoes, tsunamis, tides, and floods.
Classical and observational period
In circa 240 BC, Eratosthenes of Cyrene measured the circumference of Earth using geometry and the angle of the Sun at more than one latitude in Egypt.
There is some information about earthquakes in Aristotle's Meteorology, in Naturalis Historia by Pliny the Elder, and in Strabo's Geographica. Aristotle and Strabo recorded observations on tides.
A natural explanation of volcanoes was first undertaken by the Greek philosopher Empedocles (c. 490-430 B.C.), who considered the world to be divided into four elemental forces: earth, air, fire and water. He maintained that volcanoes were manifestation of elemental fire. Winds and earthquakes would play a key role in explanations of volcanoes. Lucretius claimed Mount Etna was completely hollow and the fires of the underground driven by a fierce wind circulating near sea level. Pliny the Elder noted that the presence of earthquakes preceded an eruption. Athanasius Kircher (1602–1680) witnessed eruptions of Mount Etna and Stromboli, then visited the crater of Vesuvius and published his view of an Earth with a central fire connected to numerous others caused by the burning of sulfur, bitumen and coal.
Instrumental and analytical period
Arguably the first modern experimental treatise was William Gilbert's De Magnete (1600), in which he deduced that compasses point north because the Earth itself is magnetic. In 1687 Isaac Newton published his Principia, which not only laid the foundations for classical mechanics and gravitation but also explained a variety of geophysical phenomena such as tides and the precession of the equinox.
These experimental and mathematical analyses were applied to several areas of geophysics: Earth's shape, density, and gravity field (Pierre Bouguer, Alexis Clairaut and Henry Cavendish), Earth's magnetic field (Alexander von Humboldt, Edmund Halley and Carl Friedrich Gauss), seismology (John Milne and Robert Mallet), and the Earth's age, heat and radioactivity (Arthur Holmes and William Thomson, 1st Baron Kelvin).
There are several descriptions and discussions about a philosophical theory of the water cycle by Marcus Vitruvius, Leonardo da Vinci and Bernard Palissy. Pioneers in hydrology include Pierre Perrault, Edme Mariotte and Edmund Halley in studies of such things as rainfall, runoff, drainage area, velocity, river cross-section measurements and discharge. Advances in the 18th century included Daniel Bernoulli's piezometer and Bernoulli's equation as well as the Pitot tube by Henri Pitot. In the 19th century, groundwater hydrology was furthered by Darcy's law, the Dupuit-Thiem well formula, and the Hagen-Poiseuille equation for flows through pipes. Physical Geography of the Sea, the first textbook of oceanography, was written by Matthew Fontaine Maury in 1855.
The thermoscope, or Galileo thermometer, was constructed by Galileo Galilei in 1607. In 1643, Evangelista Torricelli invented the mercury barometer. Blaise Pascal (in 1648) rediscovered that atmospheric pressure decreases with height, and deduced that there is a vacuum above the atmosphere.
Emergence as a discipline
The first known use of the word geophysics was by Julius Fröbel in 1834 (in German). It was used occasionally in the next few decades, but did not catch on until journals devoted to the subject began to appear, beginning with Beiträge zur Geophysik in 1887. The future Journal of Geophysical Research was founded in 1896 with the title Terrestrial Magnetism. In 1898, a Geophysical Institute was founded at the University of Göttingen, and Emil Wiechert became the world's first Chair of Geophysics. An international framework for geophysics was provided by the founding of the International Union of Geodesy and Geophysics in 1919.
20th century
The 20th century was a revolutionary age for geophysics. As an international scientific effort between 1957 and 1958, the International Geophysical Year or IGY was one of the most important for scientific activity of all disciplines of geophysics: aurora and airglow, cosmic rays, geomagnetism, gravity, ionospheric physics, longitude and latitude determinations (precision mapping), meteorology, oceanography, seismology and solar activity.
Earth's interior and seismology
Determining the physics of Earth's interior was enabled by the development of the first seismographs in the 1880s. Based on the behavior of the waves reflected off the internal layers of the Earth, several theories developed as to what would cause variances in wave speed or loss of certain frequencies. This led to scientists like Inge Lehmann discovering the presence of the Earth's core in 1936. Beno Gutenberg and Harold Jeffreys worked at explaining the difference in Earth's density due to compression and the shear velocity of waves. Since seismology is based on elastic waves, the speed of waves could help determine density and therefore the behavior of the layers within the Earth.
Nomenclature for the behavior of seismic waves was produced based on these findings. P-waves and S-waves were used to describe two types of elastic body waves possible. Love waves and Rayleigh waves were used to describe two types of surface waves possible.
Scientists who have contributed to advances in knowledge about the Earth's interior and seismology include Emil Wiechert, Beno Gutenberg, Andrija Mohorovičić, Harold Jeffreys, Inge Lehmann, Edward Bullard, Charles Francis Richter, Francis Birch, Frank Press, Hiroo Kanamori and Walter Elsasser.
One highly debated topic about Earth's interior is mantle plumes. These are theorized to be rising magma, which is responsible for the hotspots in the world, like Hawaii. Originally the theory was that mantle plumes rose up in a direct path, but now there is evidence that the plumes may deflect by small degrees as they rise. It was also found that the proposed hotspot underneath Yellowstone may not be related to a rising mantle plume. This theory has not been fully researched.
Plate tectonics
In the second half of the 20th century, plate tectonics theory was developed by several contributors including Alfred Wegener, Maurice Ewing, Robert S. Dietz, Harry Hammond Hess, Hugo Benioff, Walter C. Pitman, III, Frederick Vine, Drummond Matthews, Keith Runcorn, Bryan L. Isacks, Edward Bullard, Xavier Le Pichon, Dan McKenzie, W. Jason Morgan and John Tuzo Wilson. Prior to this, people had ideas of continental drift, but no real evidence came until the late 20th century. Alexander von Humboldt observed in the early 19th century the geometry and geology of the shores of continents of the Atlantic Ocean. James Hutton and Charles Lyell brought about the idea of gradual change, uniformitarianism, which helped people cope with the slow drift of the continents. Alfred Wegener spearheaded the original theory of continental drift and spent much of his life devoted to this theory. He proposed "Pangaea", one unified giant continent.
During the development of continental drift theory, there was not much exploration of the oceanic part of the world, only continental. Once people began to pay attention to the ocean, geologists found that the floor was spreading, and in different rates at different spots. There are three different main ways in which plates can move: transform, divergent, and Convergent. As well, there can be Rifts, areas where the land is beginning to spread apart.
Oceanography
Advances in physical oceanography occurred in the 20th century. Sea depth by acoustic measurements was first made in 1914. The German "Meteor" expedition gathered 70,000 ocean depth measurements using an echo sounder, surveying the Mid-Atlantic Ridge between 1925 and 1927. The HMS "Challenger" expedition led by Thomas Gaskell identified the record-setting Challenger Deep in 1951. The Great Global Rift was discovered by Maurice Ewing and Bruce Heezen in 1953, and the mountain range under the Arctic was found in 1954 by the Arctic Institute of the USSR. The theory of seafloor spreading was developed in 1960 by Harry Hammond Hess. The Ocean Drilling Program started in 1966. There has been much emphasis on the application of large scale computers to oceanography to allow numerical predictions of ocean conditions and as a part of overall environmental change prediction.
Geomagnetism
The motion of the conductive molten metal beneath the Earth's crust, or the Earth's dynamo, is responsible for the existence of the magnetic field. The interaction of the magnetic field and solar radiation has an impact on how much radiation reaches the surface of Earth and the integrity of the atmosphere. It has been found that the magnetic poles of the Earth have reversed several times, allowing researchers to get an idea of the surface conditions of the planet at that time. The cause of the magnetic poles being reversed is unknown, and the intervals of change vary and do not show a consistent interval. It is believed that the reversal is correlated to the Earth's mantle, although exactly how is still debated.
Distortions to the Earth's magnetic field cause the phenomenon Aurora Borealis, commonly called the Northern Lights. The magnetic field stores energy given by cosmic particles known as solar wind, which causes the magnetic field lines to expand. When the lines contract, they release this energy, which can be seen as the Northern Lights.
Atmospheric influences
The Earth's climate changes over time due to the planet's atmospheric composition, the sun's luminosity, and the occurrence of catastrophic events.
Atmospheric composition affects and is affected by the biological mechanisms active on the Earth's surface. Organisms effect the amount of oxygen vs. carbon dioxide through respiration and photosynthesis. They also affect the levels of nitrogen through fixation, nitrification, and denitrification. The ocean is capable of absorbing carbon dioxide from the atmosphere, but this varies based on the levels of nitrogen and phosphorus present in the water. Humans have also played a role in changing the atmospheric composition of the Earth through industrial byproducts, deforestation, and motor vehicles.
The luminosity of the Sun increases as it progresses through its life cycle and are visible over the course of millions of years. Sunspots can form on the Sun's surface, which can cause greater variability in the emissions that Earth receives.
Volcanoes form when two plates meet and one subducts underneath the other. They thus form along most plate boundaries; the Ring of Fire is an example of this. The study of volcanoes along plate boundaries has shown a correlation between eruptions and climate. Alan Robock theorizes that volcanic activity can influence climate and can lead to global cooling for years. The leading idea, based on volcanic eruptions, is that sulfur dioxide released from volcanoes has a major effect on the cooling of the atmosphere following the eruption.
Impacts from large celestial bodies, commonly asteroids, create shock waves that push air and distribute dust into the atmosphere, blocking sunlight. This causes global cooling, which can lead to the death and possible extinction of many species.
Industrial application
Industrial applications of geophysics were developed by demand of petroleum exploration and recovery in the 1920s. Later, petroleum, mining and groundwater geophysics were improved. Earthquake hazard minimization and soil/site investigations for earthquake-prone areas were new applications of geophysical engineering in the 1990s.
Seismology is used in the mining industry to read and build models of events that may have been caused or contributed to by the process of mining. This allows scientists to predict the hazards associated with mining in the area.
Much like mining, seismic waves are used to create models of the Earth's subsurface. Geological features, called traps, that commonly indicate the presence of oil, can be identified from the model and used to determine suitable sites to drill.
Groundwater is highly vulnerable to the pollution produced from industry and waste disposal. In order to preserve the quality of fresh water sources, maps of groundwater depth are created and compared to the locations of pollutant sources.
See also
History of geology
History of geomagnetism
Timeline of the development of tectonophysics
References
Further reading
External links
AGU History of Geophysics Committee:*
Geophysics
History of Earth science | History of geophysics | [
"Physics"
] | 2,595 | [
"Applied and interdisciplinary physics",
"Geophysics"
] |
3,113,292 | https://en.wikipedia.org/wiki/High-level%20waste | High-level waste (HLW) is a type of nuclear waste created by the reprocessing of spent nuclear fuel. It exists in two main forms:
First and second cycle raffinate and other waste streams created by nuclear reprocessing.
Waste formed by vitrification of liquid high-level waste.
Liquid high-level waste is typically held temporarily in underground tanks pending vitrification. Most of the high-level waste created by the Manhattan Project and the weapons programs of the Cold War exists in this form because funding for further processing was typically not part of the original weapons programs. Both spent nuclear fuel and vitrified waste are considered as suitable forms for long term disposal, after a period of temporary storage in the case of spent nuclear fuel.
HLW contains many of the fission products and transuranic elements generated in the reactor core and is the type of nuclear waste with the highest activity. HLW accounts for over 95% of the total radioactivity produced in the nuclear power process. In other words, while most nuclear waste is low-level and intermediate-level waste, such as protective clothing and equipment that have been contaminated with radiation, the majority of the radioactivity produced from the nuclear power generation process comes from high-level waste.
Some countries, particularly France, reprocess commercial spent fuel.
High-level waste is very radioactive and, therefore, requires special shielding during handling and transport. Initially it also needs cooling, because it generates a great deal of heat. Most of the heat, at least after short-lived nuclides have decayed, is from the medium-lived fission products caesium-137 and strontium-90, which have half-lives on the order of 30 years.
A typical large 1000 MWe nuclear reactor produces 25–30 tons of spent fuel per year. If the fuel were reprocessed and vitrified, the waste volume would be only about three cubic meters per year, but the decay heat would be almost the same.
It is generally accepted that the final waste will be disposed of in a deep geological repository, and many countries have developed plans for such a site, including Finland, France, Japan, United States and Sweden.
Definitions
High-level waste is the highly radioactive waste material resulting from the reprocessing of spent nuclear fuel, including liquid waste produced directly in reprocessing and any solid material derived from such liquid waste that contains fission products in sufficient concentrations; and other highly radioactive material that is determined, consistent with existing law, to require permanent isolation.
Spent (used) reactor fuel.
Spent nuclear fuel is used reactor fuel that is no longer efficient in creating electricity, because its fission process has slowed due to a build-up of reaction poisons. However, it is still thermally hot, highly radioactive, and potentially harmful.
Waste materials from reprocessing.
Materials for nuclear weapons are acquired by reprocessing spent nuclear fuel from breeder reactors. Reprocessing is a method of chemically treating spent fuel to separate out uranium and plutonium. The byproduct of reprocessing is a highly radioactive sludge residue.
Storage
High-level radioactive waste is stored for 10 or 20 years in spent fuel pools, and then can be put in dry cask storage facilities.
In 1997, in the 20 countries which account for most of the world's nuclear power generation, spent fuel storage capacity at the reactors was 148,000 tonnes, with 59% of this utilized. Away-from-reactor storage capacity was 78,000 tonnes, with 44% utilized.
See also
Radioactive waste
Low-level waste
Transuranic waste
Mixed waste
Into Eternity (film)
Notes
References
Fentiman, Audeen W. and James H. Saling. Radioactive Waste Management. New York: Taylor & Francis, 2002. Second ed.
Large, John H. Risks and Hazards arising the Transportation of Irradiated Fuel and Nuclear Materials in the United Kingdom R3144-A1, March 2006
External links
NRC Backgrounder on Radioactive Waste
Radioactive waste | High-level waste | [
"Chemistry",
"Technology"
] | 829 | [
"Environmental impact of nuclear power",
"Radioactive waste",
"Hazardous waste",
"Radioactivity"
] |
3,113,332 | https://en.wikipedia.org/wiki/Upsilon2%20Eridani | {{DISPLAYTITLE:Upsilon2 Eridani}}
Upsilon2 Eridani (υ² Eridani, abbreviated Upsilon2 Eri, υ2 Eri), officially named Theemin , is a star in the constellation of Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.8. Based upon parallax measurements obtained during the Hipparcos mission, it is approximately 66 parsecs (214 light-years) from the Sun.
It is an evolved red clump giant star with a stellar classification of G8+ III. The measured angular diameter is 2.21 mas. At the star's distance, this yields a physical size of around 16 times the radius of the Sun. It radiates 138 times the solar luminosity from its outer atmosphere at an effective temperature of 5074 K.
Nomenclature
υ2 Eridani (Latinised to Upsilon2 Eridani) is the star's Bayer designation.
It bore the traditional name Theemin (also written as Theemim and Beemin). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name Theemin for this star on February 1, 2017, and it is now included in the List of IAU-approved Star Names.
In the Almagest, Ptolemy called it hē kampē, "the bend in the river;" Arab writers corrupted this to bhmn, later becoming beemin, beemun in the West. Subsequently, its etymology was incorrectly derived from Hebrew תאומים (te'omim), meaning "twins," producing Theemin.
In Chinese, (), meaning Celestial Orchard, refers to an asterism consisting of Upsilon2 Eridani, Chi Eridani, Phi Eridani, Kappa Eridani, HD 16754, HD 23319, Theta Eridani, HD 24072, HD 24160, Upsilon4 Eridani, Upsilon3 Eridani and Upsilon1 Eridani. Consequently, the Chinese name for Upsilon2 Eridani itself is (, ).
References
G-type giants
Horizontal-branch stars
Eridanus (constellation)
Theemin
Eridani, Upsilon2
CD-30 01901
Eridani, 52
029291
021393
01464 | Upsilon2 Eridani | [
"Astronomy"
] | 518 | [
"Eridanus (constellation)",
"Constellations"
] |
3,113,350 | https://en.wikipedia.org/wiki/Pi1%20Cygni | {{DISPLAYTITLE:Pi1 Cygni}}
Pi1 Cygni (π1 Cygni, abbreviated Pi1 Cyg, π1 Cyg) is a binary star in the northern constellation of Cygnus. It is visible to the naked eye, having a combined apparent visual magnitude of 4.66. The distance to this system can be roughly gauged by its annual parallax shift of 1.89 mas, which yields a separation of around 1,700 light years from the Sun, give or take a hundred light years.
The two components are designated Pi1 Cygni A (officially named Azelfafage , the traditional name for the system) and B.
Nomenclature
π1 Cygni (Latinised to Pi1 Cygni) is the star's Bayer designation. The designations of the two components as Pi1 Cygni A and B derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
It bore the traditional name Azelfafage, derived from the Arabic ظلف الفرس Dhilf al-faras meaning "the horse track" or (probably) ذيل الدجاجة Dhail al-dajājah meaning "the tail of hen". In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name Azelfafage for Pi1 Cygni on 12 September 2016 and it is now so included in the List of IAU-approved Star Names. For such names relating to members of multiple star systems, and where a component letter is not explicitly listed, the WGSN says that the name should be understood to be attributed to the brightest component by visual brightness - in this case Pi1 Cygni A.
In Chinese, (), meaning Flying Serpent, refers to an asterism consisting of Pi1 Cygni, Alpha Lacertae, 4 Lacertae, Pi2 Cygni, HD 206267, Epsilon Cephei, Beta Lacertae, Sigma Cassiopeiae, Rho Cassiopeiae, Tau Cassiopeiae, AR Cassiopeiae, 9 Lacertae, 3 Andromedae, 7 Andromedae, 8 Andromedae, Lambda Andromedae, Kappa Andromedae, Psi Andromedae and Iota Andromedae. Consequently, the Chinese name for Pi1 Cygni itself is (, )
Properties
This is a single-lined spectroscopic binary with a close, circular orbit, having a period of just 26.33 days. The primary, component A, is a slightly evolved B-type subgiant star with a stellar classification of B3 IV. It has an estimated 10 times the mass of the Sun and around 5.6 times the Sun's radius. The star radiates 16,538 times the solar luminosity from its outer atmosphere at an effective temperature of roughly 18,360 K. It is about 25 million years old and is spinning with a projected rotational velocity of 55 km/s.
References
B-type subgiants
Spectroscopic binaries
Cygnus (constellation)
Cygni, Pi1
Azelfafage
BD+34 3798
Cygni, 80
206672
107136
8301 | Pi1 Cygni | [
"Astronomy"
] | 710 | [
"Cygnus (constellation)",
"Constellations"
] |
3,113,373 | https://en.wikipedia.org/wiki/Beta%20Cephei | Beta Cephei (β Cephei, abbreviated Beta Cep, β Cep) is a triple star system of the third magnitude in the constellation of Cepheus. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 690 light-years distant from the Sun. It is the prototype of the Beta Cephei variable stars.
It consists of a binary pair (designated Beta Cephei A) together with a third companion (B). The binary's two components are themselves designated Beta Cephei Aa (officially named Alfirk , the traditional name for the system) and Ab.
Nomenclature
β Cephei (Latinised to Beta Cephei) is the system's Bayer designation. The designations of the two constituents as Beta Cephei A and B, and those of A's components - Beta Cephei Aa and Ab - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
Beta Cephei bore the traditional name Alfirk, derived from the Arabic الفرقة al-firqah "the flock" (of sheep). With Alpha Cephei (Alderamin) and Eta Cephei (Alkidr), they were Al Kawākib al Firḳ الكوكب الفرق "the stars of the flock" by Ulug Beg. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name Alfirk for the component Beta Cephei Aa on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.
Visibility
Like the star Epsilon Draconis in the constellation of Draco, Beta Cephei is visible primarily in the northern hemisphere, given its extreme northern declination of 70 degrees and 34 minutes. It is nevertheless visible to most observers throughout the world reaching as far south as cities like Harare in Zimbabwe, Santa Cruz de la Sierra in Bolivia or other settlements north ± 19° South latitude. It is circumpolar throughout all of Europe, northern Asia, and North American cities as far south as Guadalajara in west central Mexico. All other locations around the globe having a latitude greater than ± 20° North will notice that the star is always visible in the night sky. Because Beta Cephei is a faint third magnitude star, it may be difficult to identify in most light polluted cities, though in rural locations the star should be easily observable.
Pole Star
Beta Cephei is a visible star located within 5° of the precessional path traced across the celestial sphere by the Earth's North pole. During the same period Iota Cephei will also be within 5° of the precessional path, on the other side so that both are in contention as pole stars, a title currently held by unambiguously by Polaris.
Properties
Beta Cephei is a triple star comprising a spectroscopic binary with a magnitude 8 optical companion. Its magnitude varies between +3.16 and +3.27 with a period of 0.19048 days.
Beta Cephei Aa is a blue subgiant star with a stellar classification of B1 IV. It has previously been classified with either a main sequence or giant luminosity class. This star has a radius that has been estimated at and a mass of . Other sources have given higher masses on the order of . Like most high-mass B-class stars, Beta Cephei Aa is a relatively young star with an estimated age of just a few million years. Like the majority of giant stars, it rotates slowly on its axis with a rotational velocity of 7 deg/day, a speed which takes the star approximately 51 days to make one complete revolution.
Beta Cephei Ab is a Be star in an 81-year orbit with the giant primary. It has been resolved using speckle interferometry at a distance of 0.25" in 1972. With a mass of about , it is likely a B-class star with a classification of B6.
B Cephei B is a magnitude 7.8 A2 main sequence star 13.6" distant.
Variability
Beta Cephei pulsates regularly every 4 hours 34 minutes, producing a variation in its visual brightness of 0.11 magnitudes. It is the prototype of the Beta Cephei class of variables, hot main sequence and giant stars that pulsate analogously to Cepheid variables but with the pulsations driven by iron opacity rather than by helium.
References
External links
Jim Kaler's Stars, University of Illinois:ALFIRK (Beta Cephei)
AAVSO Variable Star of the Month, Winter 2005: The Beta Cephei Stars and Their Relatives
An Atlas of the Universe: Multiple Star Orbits
Cepheus (constellation)
Cephei, Beta
Beta Cephei variables
B-type main-sequence stars
Alfirk
Spectroscopic binaries
Triple star systems
Cephei, 08
106032
A-type main-sequence stars
Be stars
8238
205021
Durchmusterung objects | Beta Cephei | [
"Astronomy"
] | 1,101 | [
"Constellations",
"Cepheus (constellation)"
] |
3,113,415 | https://en.wikipedia.org/wiki/Alpha%20Coronae%20Australis | Alpha Coronae Australis or α Coronae Australis, officially named Meridiana (), is the brightest star in the constellation of Corona Australis and is located about 125 light-years from Earth.
Nomenclature
α Coronae Australis (Latinised to Alpha Coronae Australis) is the star's Bayer designation.
It is the only star in the constellation with a traditional proper name, Alphekka Meridiana (Latin for 'Alphekka South'), after Alphecca, the brightest star in the constellation Corona Borealis. The name Alphecca or Alphekka is Arabic, short for نير الفكّة nayyir al-fakka "the bright (star) of the broken (ring of stars)". In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name Meridiana for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning River Turtle, refers to an asterism consisting of Alpha Coronae Australis, Alpha Telescopii, Eta1 Coronae Australis, Zeta Coronae Australis, Delta Coronae Australis, Beta Coronae Australis, Gamma Coronae Australis, Epsilon Coronae Australis, HD 175362, Kappa2 Coronae Australis and Theta Coronae Australis. Consequently, the Chinese name for Alpha Coronae Australis itself is (, .).
Properties
Alpha Coronae Australis belongs to the spectral class A2Va, making it an A-type star like Vega. Like the latter, it has excess infrared radiation, which indicates it may be ringed by a disk of dust. It has an apparent magnitude of +4.10. The star's mass and radius are estimated at 2.3 times the Sun's mass and radius. With an effective temperature of roughly 9,100 K, the star radiates a total luminosity of about 31 times the Sun's. This star is roughly 254 million years old. A rapidly rotating star, it spins at almost 200 km per second at the equator, making a complete revolution in approximately 14 hours, close to its breakup velocity.
See also
Lists of stars in the constellation Corona Australis
Class A Stars
Vega
Circumstellar disk
References
A-type main-sequence stars
Corona Australis
Coronae Australis, Alpha
Durchmusterung objects
178253
094114
7254
Meridiana | Alpha Coronae Australis | [
"Astronomy"
] | 550 | [
"Corona Australis",
"Constellations"
] |
3,113,432 | https://en.wikipedia.org/wiki/Alpha%20Hydri | Alpha Hydri, Latinized from α Hydri, is the second brightest star in the southern circumpolar constellation of Hydrus. It is readily visible to the naked eye in locations south of 28°N with an apparent visual magnitude of +2.9. It is sometimes informally known as the Head of Hydrus. This should not be confused with Alpha Hydrae (Alphard) in the constellation Hydra. Alpha Hydri is one of only three stars in the constellation Hydrus that are above the fourth visual magnitude. This star can be readily located as it lies to the south and east of the prominent star Achernar in the constellation Eridanus.
Based upon parallax measurements from the Hipparcos mission, Alpha Hydri is located at a distance of about from Earth. This subgiant star is three times larger and twice as massive as the Sun, with a stellar classification of F0 IV. It is about 810 million years old and is radiating 21 times the Sun's luminosity from its outer atmosphere at an effective temperature of 7,087 K. Alpha Hydri emits X-rays similar to Altair. The space velocity components of this star are [U, V, W] = .
Naming
In Chinese caused by adaptation of the European southern hemisphere constellations into the Chinese system, (), meaning Snake's Head, refers to an asterism consisting of α Hydri and β Reticuli. Consequently, α Hydri itself is known as (, .)
References
F-type subgiants
Hydrus
Hydri, Alpha
Durchmusterung objects
0083
012311
009236
0591 | Alpha Hydri | [
"Astronomy"
] | 354 | [
"Hydrus",
"Constellations"
] |
3,113,450 | https://en.wikipedia.org/wiki/Candle%20clock | A candle clock is a thin candle with consistently spaced marking that, when burned, indicates the passage of periods of time. While no longer used today, candle clocks provided an effective way to tell time indoors, at night, or on a cloudy day.
History
It is unknown where and when candle clocks were first used. The earliest reference to their use to
occurs in a Chinese poem by You Jiangu (AD 520). Here, the graduated candle supplied a means of determining time at night. Similar candles were used in Japan until the early 10th century.
You Jiangu's device consisted of six candles made from 72 pennyweights (24 grains each), of wax, each being 12 inches high, of uniform thickness, and divided into 12 sections each of one inch. Each candle burned away completely in four hours, making each marking 20 minutes. The candles were placed for protection inside cases made of a wooden frame with transparent horn panels in the sides.
Similar methods of measuring time were used in medieval churches. The invention of the candle clock was attributed by the Anglo-Saxons to Alfred the Great, king of Wessex. The story of how the clock was created was narrated by Asser, who lived at Alfred's court and became his close associate. Alfred used six candles, each made from 12 pennyweights of wax, and made to be high and of a uniform thickness. The candles were marked at intervals of an inch. Once lit, they were protected from the wind by being placed in a lantern made of wood and transparent horn. It would have taken 20 minutes to burn down to the next mark; the candles, burning one after the other, lasted for 24 hours.
Al-Jazari
Al-Jazari described a candle clock in 1206. It included a dial to display the time and, for the first time, employed a bayonet fitting, a fastening mechanism still used in modern times. The English engineer and historian Donald Routledge Hill described one of al-Jazari's candle clocks as follows:
References
Sources
Turner, Anthony J. The Time Museum, Volume I, Time Measuring Instruments; Part 3, Water-clocks, Sand-glasses, Fire-clocks
Candles
Chinese inventions
Clocks
Japanese inventions
ru:Огненные часы#Свечные часы | Candle clock | [
"Physics",
"Technology",
"Engineering"
] | 476 | [
"Physical systems",
"Machines",
"Clocks",
"Measuring instruments"
] |
3,113,452 | https://en.wikipedia.org/wiki/Kappa%20Leonis | Kappa Leonis, Latinized from κ Leonis, is a double star in the constellation Leo. It was called Al-minħar al-asad (), meaning "the Lion's nose." The name is corrupted to Al Minliar al Asad in the Yale Bright Star Catalogue. This star is visible to the naked eye with an apparent visual magnitude of 4.46. It has an annual parallax shift of 16.20 mas as seen from Earth, which provides a distance estimate of about 201 light years. Kappa Leonis is moving away from the Sun with a radial velocity of +28 km/s.
The primary component is an evolved K-type giant star with a stellar classification of K2 III. It is about the same age as the Sun with an estimated 144% of the Sun's mass and has expanded to 17 times the Sun's girth. It is radiating 89 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,400 K.
Kappa Leonis has a magnitude 10.4 companion at an angular separation of 2.1 arc seconds. The pair most likely form a binary star system. The companion is a suspected variable star.
References
K-type giants
Al Minliar al Asad
Leonis, Kappa
Leo (constellation)
Durchmusterung objects
Leonis, 01
081146
046146
3731 | Kappa Leonis | [
"Astronomy"
] | 291 | [
"Leo (constellation)",
"Constellations"
] |
3,113,497 | https://en.wikipedia.org/wiki/Innate%20immune%20system | The innate immune system or nonspecific immune system is one of the two main immunity strategies in vertebrates (the other being the adaptive immune system). The innate immune system is an alternate defense strategy and is the dominant immune system response found in plants, fungi, prokaryotes, and invertebrates (see Beyond vertebrates).
The major functions of the innate immune system are to:
recruit immune cells to infection sites by producing chemical factors, including chemical mediators called cytokines
activate the complement cascade to identify bacteria, activate cells, and promote clearance of antibody complexes or dead cells
identify and remove foreign substances present in organs, tissues, blood and lymph, by specialized white blood cells
activate the adaptive immune system through antigen presentation
act as a physical and chemical barrier to infectious agents; via physical measures such as skin and mucus, and chemical measures such as clotting factors and host defence peptides.
Anatomical barriers
Anatomical barriers include physical, chemical and biological barriers. The epithelial surfaces form a physical barrier that is impermeable to most infectious agents, acting as the first line of defense against invading organisms. Desquamation (shedding) of skin epithelium also helps remove bacteria and other infectious agents that have adhered to the epithelial surface. Lack of blood vessels, the inability of the epidermis to retain moisture, and the presence of sebaceous glands in the dermis, produces an environment unsuitable for the survival of microbes. In the gastrointestinal and respiratory tract, movement due to peristalsis or cilia, respectively, helps remove infectious agents. Also, mucus traps infectious agents. Gut flora can prevent the colonization of pathogenic bacteria by secreting toxic substances or by competing with pathogenic bacteria for nutrients or cell surface attachment sites. The flushing action of tears and saliva helps prevent infection of the eyes and mouth.
Inflammation
Inflammation is one of the first responses of the immune system to infection or irritation. Inflammation is stimulated by chemical factors released by injured cells. It establishes a physical barrier against the spread of infection and promotes healing of any damaged tissue following pathogen clearance.
The process of acute inflammation is initiated by cells already present in all tissues, mainly resident macrophages, dendritic cells, histiocytes, Kupffer cells, and mast cells. These cells present receptors contained on the surface or within the cell, named pattern recognition receptors (PRRs), which recognize molecules that are broadly shared by pathogens but distinguishable from host molecules, collectively referred to as pathogen-associated molecular patterns (PAMPs). At the onset of an infection, burn, or other injuries, these cells undergo activation (one of their PRRs recognizes a PAMP) and release inflammatory mediators, like cytokines and chemokines, which are responsible for the clinical signs of inflammation. PRR activation and its cellular consequences have been well-characterized as methods of inflammatory cell death, which include pyroptosis, necroptosis, and PANoptosis. These cell death pathways help clear infected or aberrant cells and release cellular contents and inflammatory mediators.
Chemical factors produced during inflammation (histamine, bradykinin, serotonin, leukotrienes, and prostaglandins) sensitize pain receptors, cause local vasodilation of the blood vessels, and attract phagocytes, especially neutrophils. Neutrophils then trigger other parts of the immune system by releasing factors that summon additional leukocytes and lymphocytes. Cytokines produced by macrophages and other cells of the innate immune system mediate the inflammatory response. These cytokines include TNF, HMGB1, and IL-1.
The inflammatory response is characterized by the following symptoms:
redness of the skin, due to locally increased blood circulation;
heat, either increased local temperature, such as a warm feeling around a localized infection, or a systemic fever;
swelling of affected tissues, such as the upper throat during the common cold or joints affected by rheumatoid arthritis;
increased production of mucus, which can cause symptoms like a runny nose or a productive cough;
pain, either local pain, such as painful joints or a sore throat, or affecting the whole body, such as body aches; and
possible dysfunction of involved organs/tissues.
Complement system
The complement system is a biochemical cascade of the immune system that helps, or "complements", the ability of antibodies to clear pathogens or mark them for destruction by other cells. The cascade is composed of many plasma proteins, synthesized in the liver, primarily by hepatocytes. The proteins work together to:
trigger the recruitment of inflammatory cells
"tag" pathogens for destruction by other cells by opsonizing, or coating, the surface of the pathogen
form holes in the plasma membrane of the pathogen, resulting in cytolysis of the pathogen cell, causing its death
rid the body of neutralised antigen-antibody complexes.
The three different complement systems are classical, alternative and lectin.
Classical: starts when antibody binds to bacteria
Alternative: starts "spontaneously"
Lectin: starts when lectins bind to mannose on bacteria
Elements of the complement cascade can be found in many non-mammalian species including plants, birds, fish, and some species of invertebrates.
White blood cells
White blood cells (WBCs) are also known as leukocytes. Most leukocytes differ from other cells of the body in that they are not tightly associated with a particular organ or tissue; thus, their function is similar to that of independent, single-cell organisms. Most leukocytes are able to move freely and interact with and capture cellular debris, foreign particles, and invading microorganisms (although macrophages, mast cells, and dendritic cells are less mobile). Unlike many other cells, most innate immune leukocytes cannot divide or reproduce on their own, but are the products of multipotent hematopoietic stem cells present in bone marrow.
The innate leukocytes include: natural killer cells, mast cells, eosinophils, basophils; and the phagocytic cells include macrophages, neutrophils, and dendritic cells, and function within the immune system by identifying and eliminating pathogens that might cause infection.
Mast cells
Mast cells are a type of innate immune cell that resides in connective tissue and in mucous membranes. They are intimately associated with wound healing and defense against pathogens, but are also often associated with allergy and anaphylaxis. When activated, mast cells rapidly release characteristic granules, rich in histamine and heparin, along with various hormonal mediators and chemokines, or chemotactic cytokines into the environment. Histamine dilates blood vessels, causing the characteristic signs of inflammation, and recruits neutrophils and macrophages.
Phagocytes
The word 'phagocyte' literally means 'eating cell'. These are immune cells that engulf, or 'phagocytose', pathogens or particles. To engulf a particle or pathogen, a phagocyte extends portions of its plasma membrane, wrapping the membrane around the particle until it is enveloped (i.e., the particle is now inside the cell). Once inside the cell, the invading pathogen is contained inside a phagosome, which merges with a lysosome. The lysosome contains enzymes and acids that kill and digest the particle or organism. In general, phagocytes patrol the body searching for pathogens, but are also able to react to a group of highly specialized molecular signals produced by other cells, called cytokines. The phagocytic cells of the immune system include macrophages, neutrophils, and dendritic cells.
Phagocytosis of the hosts' own cells is common as part of regular tissue development and maintenance. When host cells die, either by apoptosis or by cell injury due to an infection, phagocytic cells are responsible for their removal from the affected site. By helping to remove dead cells preceding growth and development of new healthy cells, phagocytosis is an important part of the healing process following tissue injury.
Macrophages
Macrophages, from the Greek, meaning "large eaters", are large phagocytic leukocytes, which are able to move beyond the vascular system by migrating through the walls of capillary vessels and entering the areas between cells in pursuit of invading pathogens. In tissues, organ-specific macrophages are differentiated from phagocytic cells present in the blood called monocytes. Macrophages are the most efficient phagocytes and can phagocytose substantial numbers of bacteria or other cells or microbes. The binding of bacterial molecules to receptors on the surface of a macrophage triggers it to engulf and destroy the bacteria through the generation of a "respiratory burst", causing the release of reactive oxygen species. Pathogens also stimulate the macrophage to produce chemokines, which summon other cells to the site of infection.
Neutrophils
Neutrophils, along with eosinophils and basophils, are known as granulocytes due to the presence of granules in their cytoplasm, or as polymorphonuclear cells (PMNs) due to their distinctive lobed nuclei. Neutrophil granules contain a variety of toxic substances that kill or inhibit growth of bacteria and fungi. Similar to macrophages, neutrophils attack pathogens by activating a respiratory burst. The main products of the neutrophil respiratory burst are strong oxidizing agents including hydrogen peroxide, free oxygen radicals and hypochlorite. Neutrophils are the most abundant type of phagocyte, normally representing 50–60% of the total circulating leukocytes, and are usually the first cells to arrive at the site of an infection. The bone marrow of a normal healthy adult produces more than 100 billion neutrophils per day, and more than 10 times that many per day during acute inflammation.
Dendritic cells
Dendritic cells (DCs) are phagocytic cells present in tissues that are in contact with the external environment, mainly the skin (where they are often called Langerhans cells), and the inner mucosal lining of the nose, lungs, stomach, and intestines. They are named for their resemblance to neuronal dendrites, but dendritic cells are not connected to the nervous system. Dendritic cells are very important in the process of antigen presentation, and serve as a link between the innate and adaptive immune systems.
Basophils and eosinophils
Basophils and eosinophils are cells related to the neutrophil. When activated by a pathogen encounter, histamine-releasing basophils are important in the defense against parasites and play a role in allergic reactions, such as asthma. Upon activation, eosinophils secrete a range of highly toxic proteins and free radicals that are highly effective in killing parasites, but may also damage tissue during an allergic reaction. Activation and release of toxins by eosinophils are, therefore, tightly regulated to prevent any inappropriate tissue destruction.
Natural killer cells
Natural killer cells (NK cells) do not directly attack invading microbes. Rather, NK cells destroy compromised host cells, such as tumor cells or virus-infected cells, recognizing such cells by a condition known as "missing self". This term describes cells with abnormally low levels of a cell-surface marker called MHC I (major histocompatibility complex) - a situation that can arise in viral infections of host cells. They were named "natural killer" because of the initial notion that they do not require activation in order to kill cells that are "missing self". The MHC makeup on the surface of damaged cells is altered and the NK cells become activated by recognizing this. Normal body cells are not recognized and attacked by NK cells because they express intact self MHC antigens. Those MHC antigens are recognized by killer cell immunoglobulin receptors (KIR) that slow the reaction of NK cells. The NK-92 cell line does not express KIR and is developed for tumor therapy.
γδ T cells
Like other 'unconventional' T cell subsets bearing invariant T cell receptors (TCRs), such as CD1d-restricted Natural Killer T cells, γδ T cells exhibit characteristics that place them at the border between innate and adaptive immunity. γδ T cells may be considered a component of adaptive immunity in that they rearrange TCR genes to produce junctional diversity and develop a memory phenotype. The various subsets may be considered part of the innate immune system where a restricted TCR or NK receptors may be used as a pattern recognition receptor. For example, according to this paradigm, large numbers of Vγ9/Vδ2 T cells respond within hours to common molecules produced by microbes, and highly restricted intraepithelial Vδ1 T cells will respond to stressed epithelial cells.
Other vertebrate mechanisms
The coagulation system overlaps with the immune system. Some products of the coagulation system can contribute to non-specific defenses via their ability to increase vascular permeability and act as chemotactic agents for phagocytic cells. In addition, some of the products of the coagulation system are directly antimicrobial. For example, beta-lysine, a protein produced by platelets during coagulation, can cause lysis of many Gram-positive bacteria by acting as a cationic detergent. Many acute-phase proteins of inflammation are involved in the coagulation system.
Increased levels of lactoferrin and transferrin inhibit bacterial growth by binding iron, an essential bacterial nutrient.
Neural regulation
The innate immune response to infectious and sterile injury is modulated by neural circuits that control cytokine production period. The inflammatory reflex is a prototypical neural circuit that controls cytokine production in the spleen. Action potentials transmitted via the vagus nerve to the spleen mediate the release of acetylcholine, the neurotransmitter that inhibits cytokine release by interacting with alpha7 nicotinic acetylcholine receptors (CHRNA7) expressed on cytokine-producing cells. The motor arc of the inflammatory reflex is termed the cholinergic anti-inflammatory pathway.
Pathogen-specificity
The parts of the innate immune system display specificity for different pathogens.
Immune evasion
Innate immune system cells prevent free growth of microorganisms within the body, but many pathogens have evolved mechanisms to evade it.
One strategy is intracellular replication, as practised by Mycobacterium tuberculosis, or wearing a protective capsule, which prevents lysis by complement and by phagocytes, as in Salmonella. Bacteroides species are normally mutualistic bacteria, making up a substantial portion of the mammalian gastrointestinal flora. Species such as B. fragilis are opportunistic pathogens, causing infections of the peritoneal cavity. They inhibit phagocytosis by affecting the phagocytes receptors used to engulf bacteria. They may also mimic host cells so the immune system does not recognize them as foreign. Staphylococcus aureus inhibits the ability of the phagocyte to respond to chemokine signals. M. tuberculosis, Streptococcus pyogenes, and Bacillus anthracis utilize mechanisms that directly kill the phagocyte.
Bacteria and fungi may form complex biofilms, protecting them from immune cells and proteins; biofilms are present in the chronic Pseudomonas aeruginosa and Burkholderia cenocepacia infections characteristic of cystic fibrosis.
Viruses
Type I interferons (IFN), secreted mainly by dendritic cells, play a central role in antiviral host defense and a cell's antiviral state. Viral components are recognized by different receptors: Toll-like receptors are located in the endosomal membrane and recognize double-stranded RNA (dsRNA), MDA5 and RIG-I receptors are located in the cytoplasm and recognize long dsRNA and phosphate-containing dsRNA respectively. When the cytoplasmic receptors MDA5 and RIG-I recognize a virus the conformation between the caspase-recruitment domain (CARD) and the CARD-containing adaptor MAVS changes. In parallel, when TLRs in the endocytic compartments recognize a virus the activation of the adaptor protein TRIF is induced. Both pathways converge in the recruitment and activation of the IKKε/TBK-1 complex, inducing dimerization of transcription factors IRF3 and IRF7, which are translocated in the nucleus, where they induce IFN production with the presence of a particular transcription factor and activate transcription factor 2. IFN is secreted through secretory vesicles, where it can activate receptors on both the cell it was released from (autocrine) or nearby cells (paracrine). This induces hundreds of interferon-stimulated genes to be expressed. This leads to antiviral protein production, such as protein kinase R, which inhibits viral protein synthesis, or the 2′,5′-oligoadenylate synthetase family, which degrades viral RNA.
Some viruses evade this by producing molecules that interfere with IFN production. For example, the Influenza A virus produces NS1 protein, which can bind to host and viral RNA, interact with immune signaling proteins or block their activation by ubiquitination, thus inhibiting type I IFN production. Influenza A also blocks protein kinase R activation and establishment of the antiviral state. The dengue virus also inhibits type I IFN production by blocking IRF-3 phosophorylation using NS2B3 protease complex.
Beyond vertebrates
Prokaryotes
Bacteria (and perhaps other prokaryotic organisms), utilize a unique defense mechanism, called the restriction modification system to protect themselves from pathogens, such as bacteriophages. In this system, bacteria produce enzymes, called restriction endonucleases, that attack and destroy specific regions of the viral DNA of invading bacteriophages. Methylation of the host's own DNA marks it as "self" and prevents it from being attacked by endonucleases. Restriction endonucleases and the restriction modification system exist exclusively in prokaryotes.
Invertebrates
Invertebrates do not possess lymphocytes or an antibody-based humoral immune system, and it is likely that a multicomponent, adaptive immune system arose with the first vertebrates. Nevertheless, invertebrates possess mechanisms that appear to be precursors of these aspects of vertebrate immunity. Pattern recognition receptors (PRRs) are proteins used by nearly all organisms to identify molecules associated with microbial pathogens. TLRs are a major class of pattern recognition receptor, that exists in all coelomates (animals with a body-cavity), including humans. The complement system exists in most life forms. Some invertebrates, including various insects, crabs, and worms utilize a modified form of the complement response known as the prophenoloxidase (proPO) system.
Antimicrobial peptides are an evolutionarily conserved component of the innate immune response found among all classes of life and represent the main form of invertebrate systemic immunity. Several species of insect produce antimicrobial peptides known as defensins and cecropins.
Proteolytic cascades
In invertebrates, PRRs trigger proteolytic cascades that degrade proteins and control many of the mechanisms of the innate immune system of invertebrates—including hemolymph coagulation and melanization. Proteolytic cascades are important components of the invertebrate immune system because they are turned on more rapidly than other innate immune reactions because they do not rely on gene changes. Proteolytic cascades function in both vertebrate and invertebrates, even though different proteins are used throughout the cascades.
Clotting mechanisms
In the hemolymph, which makes up the fluid in the circulatory system of arthropods, a gel-like fluid surrounds pathogen invaders, similar to the way blood does in other animals. Various proteins and mechanisms are involved in invertebrate clotting. In crustaceans, transglutaminase from blood cells and mobile plasma proteins make up the clotting system, where the transglutaminase polymerizes 210 kDa subunits of a plasma-clotting protein. On the other hand, in the horseshoe crab clotting system, components of proteolytic cascades are stored as inactive forms in granules of hemocytes, which are released when foreign molecules, like lipopolysaccharides enter.
Plants
Members of every class of pathogen that infect humans also infect plants. Although the exact pathogenic species vary with the infected species, bacteria, fungi, viruses, nematodes, and insects can all cause plant disease. As with animals, plants attacked by insects or other pathogens use a set of complex metabolic responses that lead to the formation of defensive chemical compounds that fight infection or make the plant less attractive to insects and other herbivores. (see: plant defense against herbivory).
Like invertebrates, plants neither generate antibody or T-cell responses nor possess mobile cells that detect and attack pathogens. In addition, in case of infection, parts of some plants are treated as disposable and replaceable, in ways that few animals can. Walling off or discarding a part of a plant helps stop infection spread.
Most plant immune responses involve systemic chemical signals sent throughout a plant. Plants use PRRs to recognize conserved microbial signatures. This recognition triggers an immune response. The first plant receptors of conserved microbial signatures were identified in rice (XA21, 1995) and in Arabidopsis (FLS2, 2000). Plants also carry immune receptors that recognize variable pathogen effectors. These include the NBS-LRR class of proteins. When a part of a plant becomes infected with a microbial or viral pathogen, in case of an incompatible interaction triggered by specific elicitors, the plant produces a localized hypersensitive response (HR), in which cells at the site of infection undergo rapid apoptosis to prevent spread to other parts of the plant. HR has some similarities to animal pyroptosis, such as a requirement of caspase-1-like proteolytic activity of VPEγ, a cysteine protease that regulates cell disassembly during cell death.
"Resistance" (R) proteins, encoded by R genes, are widely present in plants and detect pathogens. These proteins contain domains similar to the NOD Like Receptors and TLRs. Systemic acquired resistance (SAR) is a type of defensive response that renders the entire plant resistant to a broad spectrum of infectious agents. SAR involves the production of chemical messengers, such as salicylic acid or jasmonic acid. Some of these travel through the plant and signal other cells to produce defensive compounds to protect uninfected parts, e.g., leaves. Salicylic acid itself, although indispensable for expression of SAR, is not the translocated signal responsible for the systemic response. Recent evidence indicates a role for jasmonates in transmission of the signal to distal portions of the plant. RNA silencing mechanisms are important in the plant systemic response, as they can block virus replication. The jasmonic acid response is stimulated in leaves damaged by insects, and involves the production of methyl jasmonate.
See also
Antimicrobial peptides
Apoptosis
Innate lymphoid cell
NOD-like receptor
Endothelial cell tropism
References
External links
system
Innate Immune System Animation XVIVO Scientific Animation
Immune system
Insect immunity | Innate immune system | [
"Biology"
] | 4,992 | [
"Immune system",
"Organ systems"
] |
3,113,551 | https://en.wikipedia.org/wiki/Carbon%E2%80%93hydrogen%20bond | In chemistry, the carbon–hydrogen bond ( bond) is a chemical bond between carbon and hydrogen atoms that can be found in many organic compounds. This bond is a covalent, single bond, meaning that carbon shares its outer valence electrons with up to four hydrogens. This completes both of their outer shells, making them stable.
Carbon–hydrogen bonds have a bond length of about 1.09 Å (1.09 × 10−10 m) and a bond energy of about 413 kJ/mol (see table below). Using Pauling's scale—C (2.55) and H (2.2)—the electronegativity difference between these two atoms is 0.35. Because of this small difference in electronegativities, the bond is generally regarded as being non-polar. In structural formulas of molecules, the hydrogen atoms are often omitted. Compound classes consisting solely of bonds and bonds are alkanes, alkenes, alkynes, and aromatic hydrocarbons. Collectively they are known as hydrocarbons.
In October 2016, astronomers reported that the very basic chemical ingredients of life—the carbon–hydrogen molecule (CH, or methylidyne radical), the carbon–hydrogen positive ion () and the carbon ion ()—are created, in large part, using energy from the ultraviolet light of nearby stars, rather than in other ways, such as turbulent events related to supernovae and young stars, as thought earlier.
Bond length
The length of the carbonhydrogen bond varies slightly with the hybridisation of the carbon atom. A bond between a hydrogen atom and an sp2 hybridised carbon atom is about 0.6% shorter than between hydrogen and sp3 hybridised carbon. A bond between hydrogen and sp hybridised carbon is shorter still, about 3% shorter than sp3 C-H. This trend is illustrated by the molecular geometry of ethane, ethylene and acetylene.
Reactions
The C−H bond in general is very strong, so it is relatively unreactive. In several compound classes, collectively called carbon acids, the C−H bond can be sufficiently acidic for proton removal. Unactivated C−H bonds are found in alkanes and are not adjacent to a heteroatom (O, N, Si, etc.). Such bonds usually only participate in radical substitution. Many enzymes are known, however, to effect these reactions.
Although the C−H bond is one of the strongest, it varies over 30% in magnitude for fairly stable organic compounds, even in the absence of heteroatoms.
See also
Carbon–carbon bond
Carbon–nitrogen bond
Carbon–oxygen bond
Carbon–fluorine bond
References
Organic chemistry
Chemical bonding | Carbon–hydrogen bond | [
"Physics",
"Chemistry",
"Materials_science"
] | 559 | [
"Chemical bonding",
"Condensed matter physics",
"nan"
] |
3,113,736 | https://en.wikipedia.org/wiki/Plate%20heat%20exchanger | A plate heat exchanger is a type of heat exchanger that uses metal plates to transfer heat between two fluids. This has a major advantage over a conventional heat exchanger in that the fluids are exposed to a much larger surface area because the fluids are spread out over the plates. This facilitates the transfer of heat, and greatly increases the speed of the temperature change. Plate heat exchangers are now common and very small brazed versions are used in the hot-water sections of millions of combination boilers. The high heat transfer efficiency for such a small physical size has increased the domestic hot water (DHW) flowrate of combination boilers. The small plate heat exchanger has made a great impact in domestic heating and hot-water. Larger commercial versions use gaskets between the plates, whereas smaller versions tend to be brazed.
The concept behind a heat exchanger is the use of pipes or other containment vessels to heat or cool one fluid by transferring heat between it and another fluid. In most cases, the exchanger consists of a coiled pipe containing one fluid that passes through a chamber containing another fluid. The walls of the pipe are usually made of metal, or another substance with a high thermal conductivity, to facilitate the interchange, whereas the outer casing of the larger chamber is made of a plastic or coated with thermal insulation, to discourage heat from escaping from the exchanger.
The world's first commercially viable plate heat exchanger (PHE) was invented by Dr Richard Seligman in 1923 and revolutionized methods of indirect heating and cooling of fluids. Dr Richard Seligman founded APV in 1910 as the Aluminum Plant & Vessel Company Limited, a specialist fabricating firm supplying welded vessels to the brewery and vegetable oil trades. Also, it set the norm for today's computer-designed thin metal plate Heat Exchangers that are used all over the world.
Design of plate and frame heat exchangers
The plate heat exchanger (PHE) is a specialized design well suited to transferring heat between medium- and low-pressure fluids. Welded, semi-welded and brazed heat exchangers are used for heat exchange between high-pressure fluids or where a more compact product is required. In place of a pipe passing through a chamber, there are instead two alternating chambers, usually thin in depth, separated at their largest surface by a corrugated metal plate. The plates used in a plate and frame heat exchanger are obtained by one piece pressing of metal plates. Stainless steel is a commonly used metal for the plates because of its ability to withstand high temperatures, its strength, and its corrosion resistance.
The plates are often spaced by rubber sealing gaskets which are cemented into a section around the edge of the plates. The plates are pressed to form troughs at right angles to the direction of flow of the liquid which runs through the channels in the heat exchanger. These troughs are arranged so that they interlink with the other plates which forms the channel with gaps of 1.3–1.5 mm between the plates. The plates are compressed together in a rigid frame to form an arrangement of parallel flow channels with alternating hot and cold fluids. The plates produce an extremely large surface area, which allows for the fastest possible transfer. Making each chamber thin ensures that the majority of the volume of the liquid contacts the plate, again aiding exchange. The troughs also create and maintain a turbulent flow in the liquid to maximize heat transfer in the exchanger. A high degree of turbulence can be obtained at low flow rates and high heat transfer coefficient can then be achieved.
As compared to shell and tube heat exchangers, the temperature approach (the smallest difference between the temperatures of the cold and hot streams) in a plate heat exchangers may be as low as 1 °C whereas shell and tube heat exchangers require an approach of 5 °C or more. For the same amount of heat exchanged, the size of the plate heat exchanger is smaller, because of the large heat transfer area afforded by the plates (the large area through which heat can travel). Increase and reduction of the heat transfer area is simple in a plate heat-exchanger, through the addition or removal of plates from the stack.
Evaluating plate heat exchangers
All plate heat exchangers look similar on the outside. The difference lies on the inside, in the details of the plate design and the sealing technologies used. Hence, when evaluating a plate heat exchanger, it is very important not only to explore the details of the product being supplied but also to analyze the level of research and development carried out by the manufacturer and the post-commissioning service and spare parts availability.
An important aspect to take into account when evaluating a heat exchanger are the forms of corrugation within the heat exchanger. There are two types: intermating and chevron corrugations. In general, greater heat transfer enhancement is produced from chevrons for a given increase in pressure drop and are more commonly used than intermating corrugations.
There are so many different ways of modifications to increase heat exchangers efficiency that it is extremely doubtful that any of them will be supported by a commercial simulator. In addition, some proprietary data can never be released from the heat transfer enhancement manufacturers. However, it does not mean that any of the pre-measurements for emerging technology are not accomplish by the engineers. Context information on several different forms of changes to heat exchangers is given below. The main objective of having a cost benefit heat exchanger compared to the usage of a traditional heat exchanger must always be fulfilled by heat exchanger enhancement. Fouling capacity, reliability and safety are other considerations that should be tackled.
First is Periodic Cleaning. Periodic cleaning (on-site cleaning) is the most efficient method to flush out all the waste and dirt that over time decreases the efficiency of the heat exchanger. This approach requires both sides of the PHE (Plate Heat Exchanger) to be drained, followed by its isolation from the fluid in the system. From both sides, water should be flushed out until it runs completely clear. The flushing should be carried out in the opposite direction to regular operations for the best results. Once it is done, it is then time to use a circular pump and a solution tank to pass on a cleaning agent while ensuring that the agent is compatible with the PHE (Plate Heat Exchanger) gaskets and plates. Lastly, until the discharge stream runs clear, the system should be flushed with water again.
Optimization of plate heat exchangers
To achieve improvement in PHE's, two important factors namely amount of heat transfer and pressure drop have to be considered such that amount of heat transfer needs to be increased and pressure drops need to be decreased. In plate heat exchangers due to presence of corrugated plate, there is a significant resistance to flow with high friction loss. Thus to design plate heat exchangers, one should consider both factors.
For various range of Reynolds numbers, many correlations and chevron angles for plate heat exchangers exist. The plate geometry is one of the most important factor in heat transfer and pressure drop in plate heat exchangers, however such a feature is not accurately prescribed. In the corrugated plate heat exchangers, because of narrow path between the plates, there is a large pressure capacity and the flow becomes turbulent along the path. Therefore, it requires more pumping power than the other types of heat exchangers. Therefore, higher heat transfer and less pressure drop are targeted. The shape of plate heat exchanger is very important for industrial applications that are affected by pressure drop.
Flow distribution and heat transfer equation
Design calculations of a plate heat exchanger include flow distribution and pressure drop and heat transfer. The former is an issue of Flow distribution in manifolds. A layout configuration of plate heat exchanger can
be usually simplified into a manifold system with two manifold
headers for dividing and combining fluids, which can be
categorized into U-type and Z-type arrangement according to
flow direction in the headers, as shown in manifold arrangement. Bassiouny and Martin developed the previous theory of design. In recent years Wang unified all the main existing models and developed a most completed theory and design tool.
The total rate of heat transfer between the hot and cold fluids passing through a plate heat exchanger may be expressed as:
Q = UA∆Tm
where U is the Overall heat transfer coefficient, A is the total plate area, and ∆Tm is the Log mean temperature difference. U is dependent upon the heat transfer coefficients in the hot and cold streams.
Their cleaning helps to avoid fouling and scaling without the heat exchanger needing to be shut down or operations disrupted. In order to avoid heat exchanger performance to decrease and service life of the tube extension, the OnC (Online Cleaning) can be used as a standalone approach or in conjunction with chemical treatment. The re-circulating ball type system and the brush and basket system are some of OnC techniques. OfC (Offline Cleaning) is another effective cleaning method that effectively increases the performance of heat exchangers and decreases operating expenses. This method, also known as pigging, uses a shape like bullet device that is inserted in each tube and using high air pressure to force down the tube. Chemical washing, hydro-blasting and hydro-lancing are other widely used methods other than OfC. Both these techniques, when used frequently, will restore the exchanger into its optimum efficiency until the fouling and scaling begin to slip slowly and adversely affecting the efficiency of the heat exchanger.
Operation and maintenance cost is necessary for a heat exchanger. But there are different ways to minimize the cost. Firstly, cost can be minimized by reducing fouling formation on heat exchanger that decreases the overall heat transfer coefficient. According to analysis estimated, effect of fouling formation will generate a huge cost of operational losses which more than 4 billion dollars. The total fouling cost including capital cost, energy cost, maintenance cost and cost of profit loss. Chemical fouling inhibitors is one of the fouling control method. For example, acrylic acid/hydroxypropyl acrylate (AA/HPA) and acrylic acid/sulfonic acid (AA/SA) copolymers can be used to inhibit the fouling by deposition of calcium phosphate. Next, deposition of fouling can also be reduced by installing the heat exchanger vertically as the gravitational force pulls any of the particles away from the heat transfer surface in the heat exchanger.
Second, operation cost can be minimized when saturated steam is used compared to superheated steam as a fluid. Superheated steam acts as an insulator and poor heat conductor, it is not suitable for heat application such as heat exchanger.
See also
Plate fin heat exchanger
Heat transfer
LMTD
References
Bibliography
External links
A list of published articles pertaining to plate heat exchangers
A screening method for the optimal selection of plate heat exchanger configurations by J.M.Pinto and J.A.W.Gut, University of São Paulo, Brazil.
Seeking the optimal design of a typical plate heat exchanger (PHE) by Athanasios G. Kanaris, Aikaterini A. Mouza and Spiros V. Paras, Aristotle University of Thessaloniki.
Heat exchangers | Plate heat exchanger | [
"Chemistry",
"Engineering"
] | 2,280 | [
"Chemical equipment",
"Heat exchangers"
] |
3,113,840 | https://en.wikipedia.org/wiki/Traction%20%28mechanics%29 | Traction, traction force or tractive force is a force used to generate motion between a body and a tangential surface, through the use of either dry friction or shear force.
It has important applications in vehicles, as in tractive effort.
Traction can also refer to the maximum tractive force between a body and a surface, as limited by available friction; when this is the case, traction is often expressed as the ratio of the maximum tractive force to the normal force and is termed the coefficient of traction (similar to coefficient of friction). It is the force which makes an object move over the surface by overcoming all the resisting forces like friction, normal loads (load acting on the tiers in negative Z axis), air resistance, rolling resistance, etc.
Definitions
Traction can be defined as:
In vehicle dynamics, tractive force is closely related to the terms tractive effort and drawbar pull, though all three terms have different definitions.
Coefficient of traction
The coefficient of traction is defined as the usable force for traction divided by the weight on the running gear (wheels, tracks etc.) i.e.:
usable traction = coefficient of traction × normal force.
Factors affecting coefficient of traction
Traction between two surfaces depends on several factors:
Material composition of each surface.
Macroscopic and microscopic shape (texture; macrotexture and microtexture)
Normal force pressing contact surfaces together.
Contaminants at the material boundary including lubricants and adhesives.
Relative motion of tractive surfaces - a sliding object (one in kinetic friction) has less traction than a non-sliding object (one in static friction).
Direction of traction relative to some coordinate system - e.g., the available traction of a tire often differs between cornering, accelerating, and braking.
For low-friction surfaces, such as off-road or ice, traction can be increased by using traction devices that partially penetrate the surface; these devices use the shear strength of the underlying surface rather than relying solely on dry friction (e.g., aggressive off-road tread or snow chains)....
Traction coefficient in engineering design
In the design of wheeled or tracked vehicles, high traction between wheel and ground is more desirable than low traction, as it allows for higher acceleration (including cornering and braking) without wheel slippage. One notable exception is in the motorsport technique of drifting, in which rear-wheel traction is purposely lost during high speed cornering.
Other designs dramatically increase surface area to provide more traction than wheels can, for example in continuous track and half-track vehicles. A tank or similar tracked vehicle uses tracks to reduce the pressure on the areas of contact. A 70-ton M1A2 would sink to the point of high centering if it used round tires. The tracks spread the 70 tons over a much larger area of contact than tires would and allow the tank to travel over much softer land.
In some applications, there is a complicated set of trade-offs in choosing materials. For example, soft rubbers often provide better traction but also wear faster and have higher losses when flexed—thus reducing efficiency. Choices in material selection may have a dramatic effect. For example: tires used for track racing cars may have a life of 200 km, while those used on heavy trucks may have a life approaching 100,000 km. The truck tires have less traction and also thicker rubber.
Traction also varies with contaminants. A layer of water in the contact patch can cause a substantial loss of traction. This is one reason for grooves and siping of automotive tires.
The traction of trucks, agricultural tractors, wheeled military vehicles, etc. when driving on soft and/or slippery ground has been found to improve significantly by use of Tire Pressure Control Systems (TPCS). A TPCS makes it possible to reduce and later restore the tire pressure during continuous vehicle operation. Increasing traction by use of a TPCS also reduces tire wear and ride vibration.
See also
Anti-lock braking system
Equilibrium tide
Friction
Force (physics)
Karl A. Grosch
Rail adhesion
Road slipperiness
Sandbox (locomotive)
Tribology
Weight transfer
References
Force
Vehicle technology
Mechanics | Traction (mechanics) | [
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"Mathematics",
"Engineering"
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"Mass",
"Classical mechanics",
"Vehicle technology",
"Mechanics",
"Mechanical engineering by discipline",
"Mechanical engineering",
"Wikipedia categories named after physical quantities",
"Matter"
] |
3,114,084 | https://en.wikipedia.org/wiki/Cognitive%20poetics | Cognitive poetics is a school of literary criticism that applies the principles of cognitive science, particularly cognitive psychology, to the interpretation of literary texts. It has ties to reader-response criticism, and also has a grounding in modern principles of cognitive linguistics. The research and focus on cognitive poetics paves way for psychological, sociocultural and indeed linguistic dimensions to develop in relation to stylistics.
Topics addressed by cognitive poetics include deixis; text world theory (the feeling of immersion within texts); schema, script, and their role in reading; attention; foregrounding; and genre.
One of the main focal points of cognitive literary analysis is conceptual metaphor, an idea pioneered and popularized by the works of Lakoff, as a tool for examining texts. Rather than regarding metaphors as ornamental figures of speech, cognitive poetics examines how the conceptual bases of such metaphors interact with the text as a whole.
Background
Prominent figures in the field include Reuven Tsur, who is credited for originating the term,
Ronald Langacker, Mark Turner, Gerard Steen, Joanna Gavins and Peter Stockwell. Although Tsur's original, "precise and particular" sense of the term poetics was related to his theory of "poetry and perception", it has come to be "more broadly applied" to any "theory" or "system" of the workings (Greek poiesis) of literature of any genre.
During the first half of the twentieth century, emphasis was placed on the particular literary text itself. Moreover, concentration on style and linguistic placement of the texts helped to place an importance on the structural patterns prevalent within the literature. However, during this time period, attention to the human interaction aspect of literary analysis was largely unobserved.
Cognitive poetics, therefore aimed to describe how poetic language and form is naturally constrained and shaped by various human cognitive processes. It allows for the science of cognition and the literary understanding regarding literary texts to both have significance when conducting any literary analytical process. Moreover, cognitive poetics helps demonstrate how ways of expression and ways of conscious perception are mutually inclusive.
The nature of literature involves explaining its function and application in the human mind. Cognitive poetics therefore illustrates just how vital the means of comprehending and analysing literature is to the process of human cognition.
Application
Media and Everyday Life
While the framework for cognitive poetics was still in its infancy during the 1990s, the internet was simultaneously becoming an increasingly popular academic device for research purposes. This technological advancement enabled a large range of cognitive linguists to share their ideas, and scholarly awareness regarding cognitive poetics globally began to diffuse.
The current technological advancements and adjustments pertaining to the internet, social media, music, film, and television have broadened the definition of literature. Hence, the applicability of cognitive poetics to a wider scope has been realised.
The result of this recent rise in cognitive poetics solidifies the assumptions that the theory views literature as a particular type of the everyday experience, especially cognition that is innate in our general cognitive capabilities for navigating the world. It further establishes the relationship of literature with the human experience and cognition. The theory states that it is due to this relationship that humans are able to interact in these unique methods amongst each other to begin with. The consistent and overlapping nature amongst non-literary and literary backgrounds of language use is especially emphasised through the everyday application of cognitive poetics.
Cognitive-Linguistic Significance
The close link between knowledge and meaning is essential to establish in cognitive linguistic assumptions. According to these assumptions, language is understood through an individual’s knowledge of the world. In relation to cognitive poetics, this significant relationship is also deemed as crucial assumption for the theory, as this can be applied in terms of the nature and language of literature.
Cognitive linguists use metaphor as an example for the intersection between knowledge and meaning. They explain that the root of metaphor may originate from metaphorical thought, which is described to be a result of an individual’s reflection of their real-world experiences. This highlights another key assumption cognitive linguists’ maintain, that is, language, cognition and experience are closely connected.
Consequently, observing metaphors in this manner helps uncover the contextual background of the writer in question. In cognitive poetics, context is an essential notion for understanding literature.
One example of cognitive poetics using these assumptions is in the literary device of humour. Through the combination of metaphors, and the manipulation of metaphorical schemas, a writer can successfully draw upon the desired emotional response, however more research pertaining to the role of humour and cognitive poetics is needed.
See also
Cognitive philology
Cognitive rhetoric
Critical theory
Literary theory
Evolutionary psychology
Neuropsychology
References
Bibliography
Bachelard, Gaston (1960). La poétique de la rêverie. Paris: Presses Universitaires de France.
Boyd, Brian (2009). On the Origin of Stories: Evolution, Cognition, and Fiction. Harvard.
Brône, Geert and Jeroen Vandaele (2009). Cognitive Poetics. Goals, Gains and Gaps. Berlin: Mouton de Gruyter.
Campbell, Paul (2009). Cognitive Poetics: A Multimodal Approach. semioticon.com. Retrieved 2022-02-19.
Freeman, Margaret H. (2009). Cognitive Linguistic Approaches to Literary Studies: State of the Art in Cognitive Poetics. Rochester, NY.
Gavins, Joanna and Gerard Steen (2003). Cognitive Poetics in Practice. London: Routledge.
Gottschall, Jonathan (2012). The Storytelling Animal: How Stories Make Us Human. Houghton.
Semino, Elena and Jonathan Culpeper (2002). Cognitive Stylistics: Language and Cognition in Text Analysis. Amsterdam and Philadelphia: John Benjamins.
Stockwell, Peter (2002). Cognitive Poetics: An Introduction. London: Routledge.
Stockwell, Peter (2007). Cognitive Poetics and Literary Theory. 1 (1): 135–152.
Stockwell, Peter (2020). Cognitive Poetics: An Introduction. Second Edition. London: Routledge.
Tsur, Reuven (2008). Toward a Theory of Cognitive Poetics, Second, expanded and updated edition. Brighton and Portland: Sussex Academic Press.
Vermeule, Blakey (2010). Why Do We Care about Literary Characters? Baltimore: Johns Hopkins.
Wolf, Maryanne (2007). Proust and the Squid: The Story and Science of the Reading Brain. Harper.
Zunshine, Lisa (2006). Why We Read Fiction: Theory of Mind and the Novel. Ohio State University.
Cognitive linguistics
Cognitive psychology
Literary criticism
Poetics | Cognitive poetics | [
"Biology"
] | 1,352 | [
"Behavioural sciences",
"Behavior",
"Cognitive psychology"
] |
3,114,190 | https://en.wikipedia.org/wiki/Pseudohydnum%20gelatinosum | Pseudohydnum gelatinosum, commonly known as the toothed jelly fungus, cat's tongue, or jelly tooth, is an Eurasian species of fungus in the order Auriculariales. Its common names refer to its gelatinous consistency and hydnoid (toothed) undersurface.
Description
The gelatinous fruit bodies are whitish to light grayish or tan, wide, with teeth up to long. The spore print is white.
Taxonomy
A subspecies, Pseudohydnum gelatinosum ssp. pusillum, is found in North America. It is the only toothed jelly fungus known in the region.
Distribution and habitat
The species was thought to be cosmopolitan, but recent DNA evidence suggests that it is confined to Europe and northern Asia, with superficially similar (but distinct) taxa elsewhere. P. gelatinosum grows on dead conifer wood.
The North American species can be found near both coasts, between November– February on the west and July–September in other places.
Uses
The jelly tooth is edible, even raw, and it is consumed as a wild food in parts of Bulgaria, Russia, and Siberia.
References
Auriculariales
Fungi described in 1772
Fungi of Asia
Fungi of Europe
Taxa named by Giovanni Antonio Scopoli
Fungus species | Pseudohydnum gelatinosum | [
"Biology"
] | 266 | [
"Fungi",
"Fungus species"
] |
3,114,255 | https://en.wikipedia.org/wiki/History%20of%20classical%20mechanics | In physics, mechanics is the study of objects, their interaction, and motion; classical mechanics is mechanics limited to non-relativistic and non-quantum approximations. Most of the techniques of classical mechanics were developed before 1900 so the term classical mechanics refers to that historical era as well as the approximations. Other fields of physics that were developed in the same era, that use the same approximations, and are also considered "classical" include thermodynamics (see history of thermodynamics) and electromagnetism (see history of electromagnetism).
The critical historical event in classical mechanics was the publication by Isaac Newton of his laws of motion and his associated development of the mathematical techniques of calculus in 1678. Analytic tools of mechanics grew through the next two centuries, including the development of Hamiltonian mechanics and the action principles, concepts critical to the development of quantum mechanics and of relativity.
Chaos theory is a subfield of classical mechanics that was developed in its modern form in the 20th century.
Precursors to Newtonian mechanics
Antiquity
The ancient Greek philosophers, Aristotle in particular, were among the first to propose that abstract principles govern nature. Aristotle argued, in On the Heavens, that terrestrial bodies rise or fall to their "natural place" and stated as a law the correct approximation that an object's speed of fall is proportional to its weight and inversely proportional to the density of the fluid it is falling through. Aristotle believed in logic and observation but it would be more than eighteen hundred years before Francis Bacon would first develop the scientific method of experimentation, which he called a vexation of nature.
Aristotle saw a distinction between "natural motion" and "forced motion", and he believed that 'in a void' i.e.vacuum, a body at rest will remain at rest and a body in motion will continue to have the same motion. In this way, Aristotle was the first to approach something similar to the law of inertia. However, he believed a vacuum would be impossible because the surrounding air would rush in to fill it immediately. He also believed that an object would stop moving in an unnatural direction once the applied forces were removed. Later Aristotelians developed an elaborate explanation for why an arrow continues to fly through the air after it has left the bow, proposing that an arrow creates a vacuum in its wake, into which air rushes, pushing it from behind. Aristotle's beliefs were influenced by Plato's teachings on the perfection of the circular uniform motions of the heavens. As a result, he conceived of a natural order in which the motions of the heavens were necessarily perfect, in contrast to the terrestrial world of changing elements, where individuals come to be and pass away.
There is another tradition that goes back to the ancient Greeks where mathematics is used to analyze bodies at rest or in motion, which may found as early as the work of some Pythagoreans. Other examples of this tradition include Euclid (On the Balance), Archimedes (On the Equilibrium of Planes, On Floating Bodies), and Hero (Mechanica). Later, Islamic and Byzantine scholars built on these works, and these ultimately were reintroduced or became available to the West in the 12th century and again during the Renaissance.
Medieval thought
Persian Islamic polymath Ibn Sīnā published his theory of motion in The Book of Healing (1020). He said that an impetus is imparted to a projectile by the thrower, and viewed it as persistent, requiring external forces such as air resistance to dissipate it. Ibn Sina made distinction between 'force' and 'inclination' (called "mayl"), and argued that an object gained mayl when the object is in opposition to its natural motion. So he concluded that continuation of motion is attributed to the inclination that is transferred to the object, and that object will be in motion until the mayl is spent. He also claimed that projectile in a vacuum would not stop unless it is acted upon. This conception of motion is consistent with Newton's first law of motion, inertia. Which states that an object in motion will stay in motion unless it is acted on by an external force.
In the 12th century, Hibat Allah Abu'l-Barakat al-Baghdaadi adopted and modified Avicenna's theory on projectile motion. In his Kitab al-Mu'tabar, Abu'l-Barakat stated that the mover imparts a violent inclination (mayl qasri) on the moved and that this diminishes as the moving object distances itself from the mover. According to Shlomo Pines, al-Baghdaadi's theory of motion was "the oldest negation of Aristotle's fundamental dynamic law [namely, that a constant force produces a uniform motion], [and is thus an] anticipation in a vague fashion of the fundamental law of classical mechanics [namely, that a force applied continuously produces acceleration]."
In the 14th century, French priest Jean Buridan developed the theory of impetus, with possible influence by Ibn Sina. Albert, Bishop of Halberstadt, developed the theory further.
Nicole Oresme, one of Oxford Calculators at Merton College, Oxford, provided the mean speed theorem using geometrical arguments.
Renaissance
Galileo Galilei's development of the telescope and his observations further challenged the idea that the heavens were made from a perfect, unchanging substance. Adopting Copernicus's heliocentric hypothesis, Galileo believed the Earth was the same as other planets. Though the reality of the famous Tower of Pisa experiment is disputed, he did carry out quantitative experiments by rolling balls on an inclined plane; his correct theory of accelerated motion was apparently derived from the results of the experiments. Galileo also found that a body dropped vertically hits the ground at the same time as a body projected horizontally, so an Earth rotating uniformly will still have objects falling to the ground under gravity. More significantly, it asserted that uniform motion is indistinguishable from rest, and so forms the basis of the theory of relativity. Except with respect to the acceptance of Copernican astronomy, Galileo's direct influence on science in the 17th century outside Italy was probably not very great. Although his influence on educated laymen both in Italy and abroad was considerable, among university professors, except for a few who were his own pupils, it was negligible.
Christiaan Huygens was the foremost mathematician and physicist in Western Europe. He formulated the conservation law for elastic collisions, produced the first theorems of centripetal force, and developed the dynamical theory of oscillating systems. He also made improvements to the telescope, discovered Saturn's moon Titan, and invented the pendulum clock.
Newtonian mechanics
Isaac Newton was the first to unify the three laws of motion (the law of inertia, his second law mentioned above, and the law of action and reaction), and to prove that these laws govern both earthly and celestial objects. Newton and most of his contemporaries hoped that classical mechanics would be able to explain all entities, including (in the form of geometric optics) light. Newton's own explanation of Newton's rings avoided wave principles and supposed that the light particles were altered or excited by the glass and resonated.
Newton also developed the calculus which is necessary to perform the mathematical calculations involved in classical mechanics. However it was Gottfried Leibniz who, independently of Newton, developed a calculus with the notation of the derivative and integral which are used to this day. Classical mechanics retains Newton's dot notation for time derivatives.
Leonhard Euler extended Newton's laws of motion from particles to rigid bodies with two additional laws. Working with solid materials under forces leads to deformations that can be quantified. The idea was articulated by Euler (1727), and in 1782 Giordano Riccati began to determine elasticity of some materials, followed by Thomas Young. Simeon Poisson expanded study to the third dimension with the Poisson ratio. Gabriel Lamé drew on the study for assuring stability of structures and introduced the Lamé parameters. These coefficients established linear elasticity theory and started the field of continuum mechanics.
Analytical mechanics
After Newton, re-formulations progressively allowed solutions to a far greater number of problems. The first was constructed in 1788 by Joseph Louis Lagrange, an Italian-French mathematician. In Lagrangian mechanics the solution uses the path of least action and follows the calculus of variations. William Rowan Hamilton re-formulated Lagrangian mechanics in 1833, resulting in Hamiltonian mechanics. In addition to the solutions of important problems in classical physics, these techniques form the basis for quantum mechanics: Lagrangian methods evolved in to the path integral formulation and the Schrödinger equation builds Hamiltonian mechanics.
In the middle of the 19th century, Hamilton could claim classical mechanics as at the center of attention among scholars:
Origin of chaos theory
In the 1880s, while studying the three-body problem, Henri Poincaré found that there can be orbits that are nonperiodic, and yet not forever increasing nor approaching a fixed point. In 1898, Jacques Hadamard published an influential study of the chaotic motion of a free particle gliding frictionlessly on a surface of constant negative curvature, called Hadamard's billiards. Hadamard was able to show that all trajectories are unstable, in that all particle trajectories diverge exponentially from one another, with a positive Lyapunov exponent.
These developments led in the 20th century to the development of chaos theory.
Conflicts at the end of the 19th century
Although classical mechanics is largely compatible with other "classical physics" theories such as classical electrodynamics and thermodynamics, some difficulties were discovered in the late 19th century that could only be resolved by modern physics. When combined with classical thermodynamics, classical mechanics leads to the Gibbs paradox in which entropy is not a well-defined quantity. As experiments reached the atomic level, classical mechanics failed to explain, even approximately, such basic things as the energy levels and sizes of atoms. The effort at resolving these problems led to the development of quantum mechanics. Action at a distance was still a problem for electromagnetism and Newton's law of universal gravitation, these were temporary explained using aether theories. Similarly, the different behaviour of classical electromagnetism and classical mechanics under velocity transformations led to the Albert Einstein's special relativity.
Modern physics
At the beginning of the 20th century quantum mechanics (1900) and relativistic mechanics (1905) were discovered. This development indicated that classical mechanics was just an approximation of these two theories.
The theory of relativity, introduced by Einstein, would later also include general relativity (1915) that would rewrite gravitational interactions in terms of the curvature of spacetime. Relativistic mechanics recovers Newtonian mechanics and Newton's gravitational law when the speeds involved are much smaller than the speed of light and masses involved are smaller than stellar objects.
Quantum mechanics describing atomic and sub-atomic phenomena was also updated in the 1915 to quantum field theory, that would lead to the Standard Model of elementary particles and elementary interactions like electromagnetism, the strong interaction and the weak interaction. Quantum mechanics recovers classical mechanics at the macroscopic scale in the presence of decoherence.
The unification of general relativity and quantum field theory into a quantum gravity theory is still an open problem in physics.
Later developments
Emmy Noether proved the Noether's theorem in 1918 relating symmetries and conservation laws, it applies to all realms of physics including classical mechanics.
In 1954, Andrey Kolmogorov revisited the work of Poincaré. He considered the problem of whether or not a small perturbation of a conservative dynamical system resulted in a quasiperiodic orbit in celestial mechanics. The same problem was worked by Jürgen Moser and later by Vladimir Arnold, leading to the Kolmogorov–Arnold–Moser theorem and KAM theory.
Meteorologist Edward Norton Lorenz is often credited as rediscovering the field of chaos theory. About 1961, he discovered that his weather calculations were sensitive to the significant figures in the initial conditions. He later developed the theory of Lorenz system. In 1971, David Ruelle coined the term strange attractor to describe these systems. The term "chaos theory" was finally coined in 1975 by James A. Yorke.
See also
Mechanics
Timeline of classical mechanics
History of classical field theory
Notes
References
Classical mechanics
Classical mechanics
Isaac Newton | History of classical mechanics | [
"Physics"
] | 2,564 | [
"Mechanics",
"Classical mechanics"
] |
3,114,516 | https://en.wikipedia.org/wiki/Hutchinson%27s%20ratio | In ecological theory, the Hutchinson's ratio is the ratio of the size differences between similar species when they are living together as compared to when they are isolated. It is named after G. Evelyn Hutchinson who concluded that various key attributes in species varied according to the ratio of 1:1.1 to 1:1.4.
See also
Hutchinson's rule
References
External links
https://web.archive.org/web/20010228025300/http://www.limnology.org/news/30/hutchinson.html
Ecology | Hutchinson's ratio | [
"Biology"
] | 116 | [
"Ecology"
] |
3,114,537 | https://en.wikipedia.org/wiki/Pyoderma%20gangrenosum | Pyoderma gangrenosum is a rare, inflammatory skin disease where painful pustules or nodules become ulcers that progressively grow. Pyoderma gangrenosum is not infectious.
Treatments may include corticosteroids, ciclosporin, infliximab, or canakinumab.
The disease was identified in 1930. It affects approximately 1 person in 100,000 in the population. Though it can affect people of any age, it mostly affects people in their 40s and 50s.
Types
There are two main types of pyoderma gangrenosum:
the 'typical' ulcerative form, which occurs in the legs
an 'atypical' form that is more superficial and occurs in the hands and other parts of the body
Other variations are:
Peristomal pyoderma gangrenosum comprises 15% of all cases of pyoderma
Bullous pyoderma gangrenosum
Pustular pyoderma gangrenosum
Vegetative pyoderma gangrenosum
Presentation
Associations
The following are conditions commonly associated with pyoderma gangrenosum:
Inflammatory bowel disease:
Ulcerative colitis
Crohn's disease
Arthritides:
Rheumatoid arthritis
Seronegative arthritis
Hematological disease:
Myelocytic leukemia
Hairy cell leukemia
Myelofibrosis
Myeloid metaplasia
Monoclonal gammopathy
Solid tumors
A rare syndromic association called pyogenic arthritis, pyoderma gangrenosum and acne syndrome (PAPA syndrome), a type of autoinflammatory disorder, is associated with mutations in the proline-serine-threonine phosphatase-interacting 1 gene (PSTPIP1).
Causes
Though the cause is not well understood, the disease is thought to be due to immune system dysfunction, and particularly improper functioning of neutrophils. In support of an immune cause, a variety of immune mediators such as interleukin (IL)-8, IL-1β, IL-6, interferon (IFN)-γ, granulocyte colony-stimulating factor, tumor necrosis factor alpha, matrix metalloproteinase (MMP)-9, MMP10, and elafin have all been reported to be elevated in patients with pyoderma gangrenosum.
Also in support of an immune cause is the finding that at least half of all pyoderma gangrenosum patients suffer from immune-mediated diseases. For instance, ulcerative colitis, rheumatoid arthritis, and monoclonal gammopathies have all been associated with pyoderma gangrenosum. It can also be part of autoinflammatory syndromes such as PAPA syndrome. Marzano et al. (2017) identified a variety of single-nucleotide polymorphisms (SNPs) linked to autoinflammation that were carried, singly or in combination, in subsets of patients with pyoderma gangrenosum, acne and suppurative hidradenitis syndrome (PASH syndrome) or isolated pyoderma gangrenosum of the ulcerative subtype.
One hallmark of pyoderma gangrenosum is pathergy, which is the appearance of new lesions at sites of trauma, including surgical wounds.
Diagnosis
Diagnosis of PG is challenging owing to its variable presentation, clinical overlap with other conditions, association with several systemic diseases, and absence of defining histopathologic or laboratory findings. Misdiagnosis and delayed diagnosis are common. It has been shown that up to 39% of patients who initially received a diagnosis of PG have an alternative diagnosis. In light of this, validated diagnostic criteria have recently been developed for ulcerative pyoderma gangrenosum.
Diagnostic criteria
In addition to a biopsy demonstrating a neutrophilic infiltrate, patients must have at least 4 minor criteria to meet diagnostic criteria. These criteria are based on histology, history, clinical examination and treatment.
Histology: Exclusion of infection (including histologically indicated stains and tissue cultures)
Pathergy (ulcer occurring at sites of trauma, with ulcer extending past area of trauma)
Personal history of inflammatory bowel disease or inflammatory arthritis
History of papule, pustule, or vesicle that rapidly ulcerated
Clinical examination (or photographic evidence) of peripheral erythema, undermining border, and tenderness at site of ulceration
Multiple ulcerations (at least 1 occurring on an anterior lower leg)
Cribriform or “wrinkled paper” scars at sites of healed ulcers
Decrease in ulcer size within 1 month of initiating immunosuppressive medications
Treatment
First-line therapy for disseminated or localized instances of pyoderma gangrenosum is systemic treatment with corticosteroids and ciclosporin. Topical application of clobetasol, mupirocin, and gentamicin alternated with tacrolimus can be effective. Pyoderma gangrenosum ulcers demonstrate pathergy, that is, a worsening in response to minor trauma or surgical debridement. Significant care should be taken with dressing changes to prevent potentially rapid wound growth. Many patients respond differently to different types of treatment, for example some benefit from a moist environment, so treatment should be carefully evaluated at each stage.
Papules that begin as small "spouts" can be treated with Dakin's solution to prevent infection and wound clusters also benefit from this disinfectant. Wet to dry applications of Dakins can defeat spread of interior infection. Heavy drainage can be offset with Coban dressings. Grafting is not recommended due to tissue necrosis.
If ineffective, alternative therapeutic procedures include systemic treatment with corticosteroids and mycophenolate mofetil; mycophenolate mofetil and ciclosporin; tacrolimus; thalidomide; infliximab; or plasmapheresis.
See also
Superficial granulomatous pyoderma
Brown recluse spider bite
References
External links
Reactive neutrophilic cutaneous conditions
Rare diseases
Gangrene
Necrosis | Pyoderma gangrenosum | [
"Biology"
] | 1,315 | [
"Cellular processes",
"Necrosis"
] |
3,114,625 | https://en.wikipedia.org/wiki/1%2C4-Benzoquinone | 1,4-Benzoquinone, commonly known as para-quinone, is a chemical compound with the formula C6H4O2. In a pure state, it forms bright-yellow crystals with a characteristic irritating odor, resembling that of chlorine, bleach, and hot plastic or formaldehyde. This six-membered ring compound is the oxidized derivative of 1,4-hydroquinone. The molecule is multifunctional: it exhibits properties of a ketone, being able to form oximes; an oxidant, forming the dihydroxy derivative; and an alkene, undergoing addition reactions, especially those typical for α,β-unsaturated ketones. 1,4-Benzoquinone is sensitive toward both strong mineral acids and alkali, which cause condensation and decomposition of the compound.
Preparation
1,4-Benzoquinone is prepared industrially by oxidation of hydroquinone, which can be obtained by several routes. One route involves oxidation of diisopropylbenzene and the Hock rearrangement. The net reaction can be represented as follows:
C6H4(CHMe2)2 + 3 O2 → C6H4O2 + 2 OCMe2 + H2O
The reaction proceeds via the bis(hydroperoxide) and the hydroquinone. Acetone is a coproduct.
Another major process involves the direct hydroxylation of phenol by acidic hydrogen peroxide:
C6H5OH + H2O2 → C6H4(OH)2 + H2O
Both hydroquinone and catechol are produced. Subsequent oxidation of the hydroquinone gives the quinone.
Quinone was originally prepared industrially by oxidation of aniline, for example by manganese dioxide. This method is mainly practiced in PRC where environmental regulations are more relaxed.
Oxidation of hydroquinone is facile. One such method makes use of hydrogen peroxide as the oxidizer and iodine or an iodine salt as a catalyst for the oxidation occurring in a polar solvent; e.g. isopropyl alcohol.
When heated to near its melting point, 1,4-benzoquinone sublimes, even at atmospheric pressure, allowing for an effective purification. Impure samples are often dark-colored due to the presence of quinhydrone, a dark green 1:1 charge-transfer complex of quinone with hydroquinone.
Structure and redox
Benzoquinone is a planar molecule with localized, alternating C=C, C=O, and C–C bonds. Reduction gives the semiquinone anion C6H4O2−}, which adopts a more delocalized structure. Further reduction coupled to protonation gives the hydroquinone, wherein the C6 ring is fully delocalized.
Reactions and applications
Quinone is mainly used as a precursor to hydroquinone, which is used in photography and rubber manufacture as a reducing agent and antioxidant. Benzoquinonium is a skeletal muscle relaxant, ganglion blocking agent that is made from benzoquinone.
Organic synthesis
It is used as a hydrogen acceptor and oxidant in organic synthesis. 1,4-Benzoquinone serves as a dehydrogenation reagent. It is also used as a dienophile in Diels Alder reactions.
Benzoquinone reacts with acetic anhydride and sulfuric acid to give the triacetate of hydroxyquinol. This reaction is called the Thiele reaction or Thiele–Winter reaction after Johannes Thiele, who first described it in 1898, and after Ernst Winter, who further described its reaction mechanism in 1900. An application is found in this step of the total synthesis of Metachromin A:
Benzoquinone is also used to suppress double-bond migration during olefin metathesis reactions.
An acidic potassium iodide solution reduces a solution of benzoquinone to hydroquinone, which can be reoxidized back to the quinone with a solution of silver nitrate.
Due to its ability to function as an oxidizer, 1,4-benzoquinone can be found in methods using the Wacker-Tsuji oxidation, wherein a palladium salt catalyzes the conversion of an alkene to a ketone. This reaction is typically carried out using pressurized oxygen as the oxidizer, but benzoquinone can sometimes preferred. It is also used as a reagent in some variants on Wacker oxidations.
1,4-Benzoquinone is used in the synthesis of Bromadol and related analogs.
Related 1,4-benzoquinones
2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) is a stronger oxidant and dehydrogenation agent than 1,4-benzoquinone. Chloranil 1,4-C6Cl4O2 is another potent oxidant and dehydrogenation agent. Monochloro-p-benzoquinone is yet another but milder oxidant.
Metabolism
1,4-Benzoquinone is a toxic metabolite found in human blood and can be used to track exposure to benzene or mixtures containing benzene and benzene compounds, such as petrol. The compound can interfere with cellular respiration, and kidney damage has been found in animals receiving severe exposure. It is excreted in its original form and also as variations of its own metabolite, hydroquinone.
Safety
1,4-Benzoquinone is able to stain skin dark brown, cause erythema (redness, rashes on skin) and lead on to localized tissue necrosis. It is particularly irritating to the eyes and respiratory system. Its ability to sublime at commonly encountered temperatures allows for a greater airborne exposure risk than might be expected for a room-temperature solid. IARC has found insufficient evidence to comment on the compound's carcinogenicity, but has noted that it can easily pass into the bloodstream and that it showed activity in depressing bone marrow production in mice and can inhibit protease enzymes involved in cellular apoptosis.
See also
Tetrahydroxybenzoquinone
Benzoquinonetetracarboxylic acid
1,2-Benzoquinone
Quinones
Duroquinone
Ardisiaquinone
References
Oxidizing agents
Enones
ja:ベンゾキノン#1,4-ベンゾキノン | 1,4-Benzoquinone | [
"Chemistry"
] | 1,377 | [
"Redox",
"Oxidizing agents"
] |
3,114,627 | https://en.wikipedia.org/wiki/Quiet%20Electric%20Drive | Quiet Electric Drive (QED)—sometimes called by the misnomer Quiet Electronic Drive—is an Office of Naval Research (ONR)-sponsored program to develop technologies for silent maritime propulsion for the United States Navy.
According to the ONR, QED's role is to "address the Navy's operational gaps in surface ship and submarine maneuverability and acoustic signature. Quiet Electric Drives, or QEDs, are quiet, efficient and power dense. The primary objective of QED is demonstrating the utility of the motor as an actuator to obtain signature reduction performance while increasing tactical speed and maneuverability".
Its existence is known particularly via a 2007 court case in which five ethnic Chinese suspects were convicted or pleaded guilty to smuggling data from a U.S. defense contractor. An FBI affidavit stated QED to be "an extremely sensitive project ... considered by the Navy to be significant military equipment and therefore banned for export to countries specifically denied by the U.S. State Department, including the PRC (China)". Chi Mak, a naturalized U.S. citizen born in China, and four other family members were arrested during their conspiratorial attempt to transfer QED and other U.S. military technologies to the PRC via espionage.
See also
Magnetohydrodynamic drive
References
Bail Denied for Couple Allegedly Involved in Chinese Espionage Plot
US holds four China spy suspects
Equipment of the United States Navy
Marine propulsion | Quiet Electric Drive | [
"Engineering"
] | 297 | [
"Marine propulsion",
"Marine engineering"
] |
3,114,690 | https://en.wikipedia.org/wiki/Mu%20Crucis | Mu Crucis, Latinized from μ Crucis, is the seventh-brightest star in the constellation Crux commonly known as the Southern Cross. μ Crucis is a wide double star of spectral class B stars, magnitude 4.0 and 5.2 respectively. They lie about 370 light-years away, and both stars are likely physically attached. The brighter component is known as μ1 Crucis or μ Crucis A, while the fainter is μ2 Crucis or μ Crucis B.
μ1 Crucis is the brighter of the two stars with an apparent magnitude of 4.0. It is a hot massive main sequence or subgiant star, over a thousand times as luminous as the sun.
μ2 Crucis is the fainter of the pair. Its apparent magnitude is 5.2 and it is a Be star, a star spinning so quickly that it has ejected a disc of material that creates emission lines in its spectrum. The disc is inclined at 36° to our line of sight.
References
Binary stars
Crucis, Mu
Crux
B-type main-sequence stars
B-type subgiants
Lower Centaurus Crux
4898
112091 2
063003 5
Durchmusterung objects
Be stars | Mu Crucis | [
"Astronomy"
] | 264 | [
"Crux",
"Constellations"
] |
3,114,718 | https://en.wikipedia.org/wiki/Cloth%20filter | A cloth filter is a simple and cost-effective appropriate technology method for reducing the contamination of drinking water, developed for use mainly in Bangladesh. Water collected in this way has a greatly reduced pathogen count. Though not always perfectly safe, it is an improvement for poor people with limited options.
Filtering water to free it from micro-organisms has been an age-old practice among Jains who carefully remove the micro-organisms in the cloth through filtered water in order to follow doctrine of Ahimsa or non-violence, preventing pain to any living creature.
Method
The method used in Bangladesh is as follows: cloth is folded to make four or eight layers and the folded cloth is placed over a wide-mouthed container used to collect surface water. After use, it is usually sufficient to rinse the cloth and dry it in the sun for a couple of hours. In the monsoon seasons, it may be advisable to use a cheap disinfectant to decontaminate the material.
The preferred cloth is used cotton sari cloth. Other types of clean, used cloth can be used with some effect, though the effectiveness will vary significantly. Used cloth is more effective than new cloth, as the repeated washing reduces the space between the fibers.
Effectiveness
The cloth is effective because most pathogens are attached to particles and plankton, particularly a type of zooplankton called copepods, within the water. By passing the water through an effective filter, most cholera bacteria and other pathogens are removed. It has been demonstrated to greatly reduce cholera infections in poor villages where disinfectants and fuel for boiling are difficult to get.
In sub-Saharan Africa where guinea worm infections (dracunculiasis) are endemic, infection is prevented by use of a nylon mesh with pore size of approximately 150 μm to filter out the copepods that host the parasite.
An old folded cotton sari creates a smaller effective mesh size (approximately 20-μm). This should be small enough to remove all zooplankton, most phytoplankton, and thus a large proportion of the cholera in the water (99%, according to laboratory studies). However, the nylon net with the larger mesh size was found to be "almost equally effective."
The cloth filter provides less than ideal purification on its own - usually filtering is an initial step, to be followed by further disinfection. However, where there are no other options, water professionals may consider that it is "of course, better than nothing"
Background
The cloth filter has been studied and reported on by Rita Colwell and Anwar Huq from the University of Maryland Biotechnology Institute, together with other researchers from the United States and Bangladesh. They report that: "It is common practice in villages in Bangladesh to use cloth, frequently a flat, unfolded piece of an old sari, to filter home-prepared drinks".
The researchers studied the application of this technique to drinking water, with folded cloth. They studied the pore size of the cloth, the effect of folding the cloth on the effective pore size, the ability of the cloth to remove particles and plankton, as well as the effect on rates of cholera when used in a Bangladesh village.
See also
Filtration
References
External links
Safe Saris - Bangladesh
NSF Director Colwell Fights Spread of Cholera with Saris
Sari filter stops cholera, with photo. ICDDR,B website.
Photo showing woman using sari to filter drinking water - Source: Dr. Rita Colwell
Filters
Water
Appropriate technology
Survival skills | Cloth filter | [
"Chemistry",
"Engineering",
"Environmental_science"
] | 720 | [
"Hydrology",
"Chemical equipment",
"Filters",
"Filtration",
"Water"
] |
3,114,847 | https://en.wikipedia.org/wiki/Animal%20roleplay | Animal roleplay is a form of roleplay where at least one participant plays the part of a non-human animal. As with most forms of roleplay, its uses include play and psychodrama.
Animal roleplay may also be found in BDSM contexts, where an individual may take part in a dominant/submissive relationship by being treated as an animal. The activity is often referred to as petplay. However, not all types of animal roleplay within BDSM are petplay and not all petplay in BDSM involves roleplaying as an animal; some can be referred to as primal play.
Overview
The origins of animal roleplay and petplay are probably various and diverse, again depending upon the participants involved. However, its origins are certainly influenced by costuming, fiction, myth and legend, roleplay and psychodrama in their various aspects. Some of the earliest published images of animal play (especially pony play) are to be found in the work of John Willie, primarily in Bizarre magazine published from 1946 to 1959.
Some of the equipment that can be used in animal roleplay include leash, chain, bit gag, neck collar, bondage harness, catsuit, bodystocking, butt plug, muzzle, ballet boots, etc.
Cultural and ritual use
Non-sexual animal roleplay was a common and integral part of ritual in many tribal cultures both in recent and likely prehistoric times, where a member (or members) of the tribe would take the role physically and often spiritually of an animal that was either revered or hunted. Examples of the former include many of the American Indian tribes and Arctic native peoples. Examples of the latter are evidenced by cave paintings. In 1911, Julia Tuell photographed the last Animal Dance ("Massaum") performed by the Northern Cheyenne of Montana.
It is also sometimes used in education, especially physical education, as a way to encourage people to exercise the body in unusual ways, by mimicking various animals.
Other forms
Some superheroes, heroines, and villains also feature elements related to pet play; such as DC Comics's Wildcat, Batman, Catwoman, the Penguin and Vixen, Marvel's Tigra, Man-Wolf and Black Cat, or even Nastassja Kinski's Irena Gallier in the 1982 film Cat People (a remake of the 1942 Simone Simon film), and Miss Kitty from the Brendan Fraser movie Monkeybone. All involve animal qualities taken on by a human. Some would even count the enactment or spiritual belief in therianthropy (werewolves, werecats, etc.) as falling under human animal roleplay or transformation play as well.
Peter Shaffer's 1973 play Equus tells the story of a young man who has a pathological religious fascination with horses, but this appears closer to zoophilia than pet play. Andrew Lloyd Webber's 1981 musical Cats traces a tribe of urban cats, and in 2007 War Horse used full size puppets to play horses on stage.
Erotic scenarios
Like much of erotic play and roleplay, animal roleplay in an erotic or relational context is entirely defined by the people involved and by their mood and interests at the time of play. It ranges from the simple imitation of a vocal "whinnying" of a horse to the barking, panting or playful nudging of a puppy, or playful behaviour of a kitten, to crawling around on all fours and being fed, or petted, by hand. To the greater extremes of dressing up as a pony in modified horse tack, masks, prosthetics and temporary bondage based body modification (such as binding the forearms to the upperarms and/or the calves to the thighs).
Public participation in human animal roleplay is varied. A couple could inconspicuously role-play a pet play scene in public, which would look to the casual observer like one partner is merely stroking the other's neck. In the case of some BDSM fetishists, one partner may wear a collar with a leash attached.
The reasons for playing such a character or animal can vary as much as the physical manifestations and intensity of the play. Some people enjoy being able to "cut loose" into a different, or more dynamic personality (see other variations). In some cases, pet play is seen as a loving, quiet cuddling time where there is no need for verbalizations and the simple act of stroking, rubbing and holding the other partner is satisfying or reassuring in and of itself for those involved. For others, there may be a spiritual side to it. Some feel closer to their animal totem, while others may identify with something akin to a deeper side or part of their own psyche (known as therianthropy). For still others, there is the experience of power exchange setup in a context or structure which they can accept.
Some cases could be considered a type of animal transformation fantasy. They can have strong elements of exhibitionism, be totally enjoyed in the privacy of the home, or lie somewhere between either boundary. While not widespread, erotic human-animal roleplay is still enjoyed by a sizable number of people. However, it is still primarily identified with BDSM practice. Though commonly misinterpreted as being associated with furry or other alternative lifestyle activities, that is generally not the case though some instances may exist.
For most participants, it has no connection whatsoever with bestiality, which is controversial and would usually be considered edgeplay in BDSM circles.
Other considerations
Each type of play can focus on a certain "strength" of an animal character. Pony play often involves the practice and training that a horse owner or trainer would put their horse through to learn how to walk, canter, etc., as modified for human limbs. Puppy and kitten play often can involve BDSM related discipline. Cow Play often involves fantasies of lactation and impregnation. The usual limits of safe, sane and consensual apply to roleplay as much as any other activity between humans who accept and respect their partner's interests and limits. For most, this does not include bestiality.
Just because one partner is playing the "pet" does not necessarily make them the passive or submissive play partner in the scene.
BDSM scenarios
Some people believe that they have certain animal 'instincts' and that they can let them out through animal roleplay. This is especially true in the BDSM communities, where some people 'live' as their chosen animal 24/7. This type of mentality goes beyond roleplay and becomes a full lifestyle for the parties involved. There are also 'hybrids'. These are humans who live part-time as one type of animal, and part-time as another. This is usually determined by the situation.
In the BDSM scene, people engage in animal roleplay to build stronger emotional connections. People develop deep emotional connections with their pets. Petplay, especially pup and kitten play seeks to create the same deep emotional connection between the owner/master and submissive/pet. The dom may demand unconditional love and obedience, but they may also train their pet to be more emotionally perceptive and empathic. This helps the sub feel safe and secure in the relationship.
Types of animal roleplay
The following section lists specific animal roleplay communities centered around a single type of animal.
Pony play
Pony play is where at least one of the participants dresses to resemble and assumes the mannerisms and character of an equine animal. A documentary film Pony Passion was produced by British pony play club De Ferre in 2003 showing their club's activities and the 2005 documentary film, Born in a Barn, depicted the lives of several pony-play enthusiasts.
Pony play is sometimes referred to as "The Aristotelian Perversion" or "Aristotle’s Perversion", in reference to Phyllis and Aristotle, an apocryphal story where the philosopher Aristotle was persuaded to let a woman named Phyllis ride him like a horse, in promised exchange for sexual favors: an episode depicted in various woodcuts and other works of art.
Kitten play
In kitten play, a person dresses to resemble and assumes the mannerisms and character of a kitten or cat, a characteristic of which is that it keeps some independence and, as part of the fantasy, might retaliate against the partner trying to tame/train them. Some might be trained to do tricks such as bring toys back, to beg, or go on walks. A "kitten" or "cat" that is unowned or uncollared may be called a "stray".
Pup play
Pup play is a game where participants take on the persona of a dog or puppy. It can involve wearing dog-like accessories, such as hoods, mitts, and tails, and acting like a canine. This play can be done alone, with other pups, or with a handler, trainer, or master. It's especially popular in the LGBTQ community.
HuCow
HuCow participants broadly consider themselves as cows or farmers. The cow is usually submissive and objectified by the farmer. Scenes are often centered around the farmer milking the human cow's breasts. Human cows are often portrayed with large-sized breasts or pecs, as being able to lactate.
See also
Animal transformation fantasy (disambiguation)
Cat Girl Manor
Consent (BDSM)
Erotic humiliation
Fur fetishism
Human furniture
Master slave relationship
Animal roleplay in ancient Rome
Sexual roleplay
Zoophilia
References
External links
Dog play entry in the BDSM Dictionary
An Introduction to Pet Play
Sexual fetishism
Sexual roleplay
Sexology
Sexual attraction | Animal roleplay | [
"Biology"
] | 1,972 | [
"Behavioural sciences",
"Behavior",
"Sexology"
] |
3,114,930 | https://en.wikipedia.org/wiki/Vector%20calculus%20identities | The following are important identities involving derivatives and integrals in vector calculus.
Operator notation
Gradient
For a function in three-dimensional Cartesian coordinate variables, the gradient is the vector field:
where i, j, k are the standard unit vectors for the x, y, z-axes. More generally, for a function of n variables , also called a scalar field, the gradient is the vector field:
where are mutually orthogonal unit vectors.
As the name implies, the gradient is proportional to, and points in the direction of, the function's most rapid (positive) change.
For a vector field , also called a tensor field of order 1, the gradient or total derivative is the n × n Jacobian matrix:
For a tensor field of any order k, the gradient is a tensor field of order k + 1.
For a tensor field of order k > 0, the tensor field of order k + 1 is defined by the recursive relation
where is an arbitrary constant vector.
Divergence
In Cartesian coordinates, the divergence of a continuously differentiable vector field is the scalar-valued function:
As the name implies, the divergence is a (local) measure of the degree to which vectors in the field diverge.
The divergence of a tensor field of non-zero order k is written as , a contraction of a tensor field of order k − 1. Specifically, the divergence of a vector is a scalar. The divergence of a higher-order tensor field may be found by decomposing the tensor field into a sum of outer products and using the identity,
where is the directional derivative in the direction of multiplied by its magnitude. Specifically, for the outer product of two vectors,
For a tensor field of order k > 1, the tensor field of order k − 1 is defined by the recursive relation
where is an arbitrary constant vector.
Curl
In Cartesian coordinates, for the curl is the vector field:
where i, j, and k are the unit vectors for the x-, y-, and z-axes, respectively.
As the name implies the curl is a measure of how much nearby vectors tend in a circular direction.
In Einstein notation, the vector field has curl given by:
where = ±1 or 0 is the Levi-Civita parity symbol.
For a tensor field of order k > 1, the tensor field of order k is defined by the recursive relation
where is an arbitrary constant vector.
A tensor field of order greater than one may be decomposed into a sum of outer products, and then the following identity may be used:
Specifically, for the outer product of two vectors,
Laplacian
In Cartesian coordinates, the Laplacian of a function is
The Laplacian is a measure of how much a function is changing over a small sphere centered at the point.
When the Laplacian is equal to 0, the function is called a harmonic function. That is,
For a tensor field, , the Laplacian is generally written as:
and is a tensor field of the same order.
For a tensor field of order k > 0, the tensor field of order k is defined by the recursive relation
where is an arbitrary constant vector.
Special notations
In Feynman subscript notation,
where the notation ∇B means the subscripted gradient operates on only the factor B.
Less general but similar is the Hestenes overdot notation in geometric algebra. The above identity is then expressed as:
where overdots define the scope of the vector derivative. The dotted vector, in this case B, is differentiated, while the (undotted) A is held constant.
The utility of the Feynman subscript notation lies in its use in the derivation of vector and tensor derivative identities, as in the following example which uses the algebraic identity C⋅(A×B) = (C×A)⋅B:
An alternative method is to use the Cartesian components of the del operator as follows:
Another method of deriving vector and tensor derivative identities is to replace all occurrences of a vector in an algebraic identity by the del operator, provided that no variable occurs both inside and outside the scope of an operator or both inside the scope of one operator in a term and outside the scope of another operator in the same term (i.e., the operators must be nested). The validity of this rule follows from the validity of the Feynman method, for one may always substitute a subscripted del and then immediately drop the subscript under the condition of the rule.
For example, from the identity A⋅(B×C) = (A×B)⋅C
we may derive A⋅(∇×C) = (A×∇)⋅C but not ∇⋅(B×C) = (∇×B)⋅C,
nor from A⋅(B×A) = 0 may we derive A⋅(∇×A) = 0.
On the other hand, a subscripted del operates on all occurrences of the subscript in the term, so that A⋅(∇A×A) = ∇A⋅(A×A) = ∇⋅(A×A) = 0.
Also, from A×(A×C) = A(A⋅C) − (A⋅A)C we may derive ∇×(∇×C) = ∇(∇⋅C) − ∇2C,
but from (Aψ)⋅(Aφ) = (A⋅A)(ψφ) we may not derive (∇ψ)⋅(∇φ) = ∇2(ψφ).
For the remainder of this article, Feynman subscript notation will be used where appropriate.
First derivative identities
For scalar fields , and vector fields , , we have the following derivative identities.
Distributive properties
First derivative associative properties
Product rule for multiplication by a scalar
We have the following generalizations of the product rule in single-variable calculus.
Quotient rule for division by a scalar
Chain rule
Let be a one-variable function from scalars to scalars, a parametrized curve, a function from vectors to scalars, and a vector field. We have the following special cases of the multi-variable chain rule.
For a vector transformation we have:
Here we take the trace of the dot product of two second-order tensors, which corresponds to the product of their matrices.
Dot product rule
where denotes the Jacobian matrix of the vector field .
Alternatively, using Feynman subscript notation,
See these notes.
As a special case, when ,
The generalization of the dot product formula to Riemannian manifolds is a defining property of a Riemannian connection, which differentiates a vector field to give a vector-valued 1-form.
Cross product rule
Note that the matrix is antisymmetric.
Second derivative identities
Divergence of curl is zero
The divergence of the curl of any continuously twice-differentiable vector field A is always zero:
This is a special case of the vanishing of the square of the exterior derivative in the De Rham chain complex.
Divergence of gradient is Laplacian
The Laplacian of a scalar field is the divergence of its gradient:
The result is a scalar quantity.
Divergence of divergence is not defined
The divergence of a vector field A is a scalar, and the divergence of a scalar quantity is undefined. Therefore,
Curl of gradient is zero
The curl of the gradient of any continuously twice-differentiable scalar field (i.e., differentiability class ) is always the zero vector:
It can be easily proved by expressing in a Cartesian coordinate system with Schwarz's theorem (also called Clairaut's theorem on equality of mixed partials). This result is a special case of the vanishing of the square of the exterior derivative in the De Rham chain complex.
Curl of curl
Here ∇2 is the vector Laplacian operating on the vector field A.
Curl of divergence is not defined
The divergence of a vector field A is a scalar, and the curl of a scalar quantity is undefined. Therefore,
Second derivative associative properties
A mnemonic
The figure to the right is a mnemonic for some of these identities. The abbreviations used are:
D: divergence,
C: curl,
G: gradient,
L: Laplacian,
CC: curl of curl.
Each arrow is labeled with the result of an identity, specifically, the result of applying the operator at the arrow's tail to the operator at its head. The blue circle in the middle means curl of curl exists, whereas the other two red circles (dashed) mean that DD and GG do not exist.
Summary of important identities
Differentiation
Gradient
Divergence
Curl
Vector-dot-Del Operator
Second derivatives
(scalar Laplacian)
(vector Laplacian)
(Green's vector identity)
Third derivatives
Integration
Below, the curly symbol ∂ means "boundary of" a surface or solid.
Surface–volume integrals
In the following surface–volume integral theorems, V denotes a three-dimensional volume with a corresponding two-dimensional boundary S = ∂V (a closed surface):
(divergence theorem)
(Green's first identity)
(Green's second identity)
(integration by parts)
(integration by parts)
(integration by parts)
Curve–surface integrals
In the following curve–surface integral theorems, S denotes a 2d open surface with a corresponding 1d boundary C = ∂S (a closed curve):
(Stokes' theorem)
Integration around a closed curve in the clockwise sense is the negative of the same line integral in the counterclockwise sense (analogous to interchanging the limits in a definite integral):
Endpoint-curve integrals
In the following endpoint–curve integral theorems, P denotes a 1d open path with signed 0d boundary points and integration along P is from to :
(gradient theorem)
Tensor integrals
A tensor form of a vector integral theorem may be obtained by replacing the vector (or one of them) by a tensor, provided that the vector is first made to appear only as the right-most vector of each integrand. For example, Stokes' theorem becomes
.
A scalar field may also be treated as a vector and replaced by a vector or tensor. For example, Green's first identity becomes
.
Similar rules apply to algebraic and differentiation formulas. For algebraic formulas one may alternatively use the left-most vector position.
See also
References
Further reading
Mathematical identities
Mathematics-related lists
Vector calculus
eo:Vektoraj identoj
zh:向量恆等式列表 | Vector calculus identities | [
"Mathematics"
] | 2,191 | [
"Algebra",
"Mathematical theorems",
"Mathematical problems",
"Mathematical identities"
] |
3,115,081 | https://en.wikipedia.org/wiki/Phase-change%20incubator | The phase-change incubator is a low-cost, low-maintenance incubator that tests for microorganisms in water supplies. It uses small balls containing a chemical compound that, when heated and then kept insulated, will stay at 37 °C (approx. 99 °F) for 24 hours. This allows cultures to be tested without the need for a laboratory or an expensive portable incubator. Thus it is particularly useful for poor or remote communities. The phase-change incubator was developed in the late 1990s by Amy Smith, when she was a graduate student at MIT. Smith has also started a non-profit organization called A Drop in the Bucket to distribute the incubators and to train people on how to use them to test water quality. Her “Test Water Cheap” system could be used at remote locations to test for bacteria such as E.coli.
Embrace, an organization that from Stanford University, is applying a similar concept to design low-cost incubators for premature and low birth weight babies in developing countries.
See also
Appropriate technology
References
External links
Student's low-cost solution aids high-tech problem in Africa
Necessity Is the Mother of Invention
American inventions
Appropriate technology
Microbiology equipment | Phase-change incubator | [
"Biology"
] | 247 | [
"Microbiology equipment"
] |
3,115,123 | https://en.wikipedia.org/wiki/Email%20tracking | Email tracking or email tracker is a method for monitoring whether the email message is read by the intended recipient. Most tracking technologies use some form of digitally time-stamped record to reveal the exact time and date when an email is received or opened, as well as the IP address of the recipient.
Email tracking is useful when the sender wants to know whether the intended recipient actually received the email or clicked the links. However, due to the nature of the technology, email tracking cannot be considered an absolutely accurate indicator that a message was opened or read by the recipient.
Most email marketing software provides tracking features, sometimes in aggregate (e.g., click-through rate), and sometimes on an individual basis.
Read-receipts
Some email applications, such as Microsoft Office Outlook and Mozilla Thunderbird, employ a read-receipt tracking mechanism. The sender selects the receipt request option prior to sending the message, and then upon sending, each recipient has the option of notifying the sender that the message was received or read by the recipient.
However, requesting a receipt does not guarantee that one will be received, for several reasons. Not all email applications or services support sending read receipts, and users can usually disable the functionality if they so wish. Those that do support it are not necessarily compatible with or capable of recognizing requests from a different email service or application. Generally, read receipts are only useful within an organization where all mail users are using the same email service and application.
Depending on the recipient's mail client and settings, they may be forced to click a notification button before they can move on with their work. Even though it is an opt-in process, a recipient might consider it inconvenient, discourteous, or invasive.
Read receipts are sent back to the sender's "inbox" as email messages, but the location may be changed depending on the software used and its configuration. Additional technical information, such as the sender's details, the email software they use, the IP addresses of the sender, and their email server is commonly available inside the headers of the read receipt.
The technical term for these is "MDN - Message Disposition Notifications", and they are requested by inserting one or more of the following lines into the email headers: "X-Confirm-Reading-To:"; "Disposition-Notification-To:"; or "Return-Receipt-To:".
Several email tracking services also feature real-time notifications, producing an on-screen pop-up whenever the sender's email has been opened.
Return-receipts
Another kind of receipt can be requested, which is called a DSN (delivery status notification), which is a request to the recipient's email server to send the sender a notification about the delivery of an email that the sender has just sent. The notification takes the form of an email, and will indicate whether the delivery succeeded, failed, or got delayed, and it will warn the sender if any email server involved was unable to give the sender a receipt. DSNs are requested at the time of sending by the sending application or server software (not inside the email or headers itself), and the sender can request to "Never" get any, to "Always" get one, or (which most software does by default) only to get a DSN if delivery fails (i.e.: not for success, delay, or relay DSNs). These failure DSNs are normally referred to as a "Bounce". Additionally, the sender can specify in their DSN request whether the sender wants their receipt to contain a full copy of their original email, or just a summary of what happened. In the SMTP protocol, DSNs are requested at the end of the RCPT TO: command (e.g.: RCPT TO:<> NOTIFY=SUCCESS, DELAY) and the MAIL FROM: command (e.g.: MAIL FROM:<> RET=HDRS).
Email marketing and tracking
Some email marketing tools include tracking as a feature. Such email tracking is usually accomplished using standard web tracking devices known as cookies and web beacons. When an email message is sent, if it is a graphical HTML message (not a plain text message) the email marketing system may embed a tiny, invisible tracking image (a single-pixel gif, sometimes called a web beacon) within the content of the message. When the recipient opens the message, the tracking image is referenced. When they click a link or open an attachment, another tracking code is activated. In each case a separate tracking event is recorded by the system. These response events accumulate over time in a database, enabling the email marketing software to report metrics such as open-rate and click-through rate. Email marketing users can view reports on both aggregate response statistics and individual response over time.
Such email tracking services are used by many companies, but are also available for individuals as subscription services, either web-based or integrated into email clients such as Microsoft Outlook or Gmail
Email tracking services may also offer collations of tracked data, allowing users to analyze the statistics of their email performance.
Privacy issues
Email tracking is used by individuals and businesses including email marketers, help desks, spammers and phishers to verify that emails are actually read by recipients, that email addresses are valid, and that the content of emails has made it past spam filters. Such tracking can also reveal if emails get forwarded, but who emails get forwarded to are usually not noted. About 24.7% of all emails track their recipients, but no more than half of the users are aware of being tracked. When used maliciously, it can be used to collect confidential information about businesses and individuals and to create more effective phishing schemes.
Common data that can be accessed from email tracking includes, but is not limited to, the IP address, client device
properties (desktop or mobile, browser type and version), and a date/time stamp of when the email was read.
The tracking mechanisms employed are typically first-party cookies and web beacons.
HP email tracking scandal
In the U.S. Congressional Inquiry investigating the
HP pretexting scandal
it was revealed that HP security used an email tracking service called
ReadNotify.com to investigate boardroom leaks.
The California attorney general's office has said that this practice
was not part of the pretexting charges.
HP said they consider email tracking to be legitimate and will continue using it.
See also
Email privacy
Spy pixel
Document automation in supply chain management & logistics
Bounce message
References
Email
Tracking | Email tracking | [
"Technology"
] | 1,356 | [
"Tracking",
"Wireless locating"
] |
3,115,142 | https://en.wikipedia.org/wiki/Council%20for%20Responsible%20Genetics | The Council for Responsible Genetics (CRG) was a nonprofit NGO with a focus on biotechnology.
History
The Council for Responsible Genetics was founded in 1983 in Cambridge, Massachusetts.
An early voice concerned about the social and ethical implications of modern genetic technologies, CRG organized a 1985 Congressional Briefing and a 1986 panel of the American Association for the Advancement of Science, both focusing on the potential dangers of genetically engineered biological weapons. Francis Boyle was asked to draft legislation setting limits on the use of genetic engineering, leading to the Biological Weapons Anti-Terrorism Act of 1989.
CRG was the first organization to advance a comprehensive, scientifically based position against human germline engineering. It was also the first to compile documented cases of genetic discrimination, laying the intellectual groundwork for the Genetic Information Nondiscrimination Act of 2008 (GINA).
The organization created both a Genetic Bill of Rights and a Citizen's Guide to Genetically Modified Food. Also notable are CRG's support for the "Safe Seeds Campaign" (for avoiding gene flow from genetically engineered to non-GE seed) and the organization of a US conference on Forensic DNA Databanks and Racial Disparities in the Criminal Justice System. In 2010 CRG led a successful campaign to roll back a controversial student genetic testing program at the University of California, Berkeley. In 2011, CRG led a campaign to successfully enact [CalGINA] in California, which extended genetic privacy and nondiscrimination protections to life, disability and long term care insurance, mortgages, lending and other areas.
CRG issued five anthologies of commentaries:
Rights and Liberties in the Biotech Age edited by Sheldon Krimsky and Peter Shorett
Race and the Genetic Revolution: Science, Myth and Culture
Genetic Explanations: Sense and Nonsense edited by Krimsky and Jeremy Gruber
Biotechnology in our Lives edited by Krimsky and Gruber
The GMO Deception edited by Krimsky and Gruber
Principles and projects
CRG "fosters public debate about the social, ethical and environmental implications of genetic technologies." They list three central principles:
The public must have access to clear and understandable information on technological innovations.
The public must be able to participate in public and private decision making concerning technological developments and their implementation.
New technologies must meet social needs. Problems rooted in poverty, racism, and other forms of inequality, according to CRG, cannot be remedied by technology alone.
In 2007, CRG hosted a retreat to refresh the mission statement and determine goals for the future of the organization. The outcome was that CRG should:
Explore and document developments in biotechnology through a holistic approach that considers science within a social, cultural, ethical, and environmental context.
Serve as a global knowledge resource, providing information and education about the potential impact of new and emerging biotechnologies.
Develop concrete policy solutions to address what CRG feels are emerging issues in biotechnology.
Mobilize and collaborate with scientists and other organizations to inform the public and promote democratic control of science.
Expose what CRG views as over-simplified and distorted claims regarding the role of genetics in human disease, development and behavior.
The pioneering contributions of CRG to public interest initiatives concerned with appropriate use of biotechnologies are recounted in the book Biotech Juggernaut: Hope, Hype, and Hidden Agendas of Entrepreneurial Bioscience (Routledge, 2019).
GeneWatch
The CRG publishes Genewatch, America's first and (according to CRG in 2009) only magazine dedicated to monitoring biotechnology's social, ethical and environmental consequences. The publication covers a broad spectrum of issues, from genetically modified food to biological weapons, genetic privacy and discrimination, reproductive technology, and human cloning. Established in 1983, the publication won the Utne Independent Press Award for General Excellence in the category of newsletters in 2006.
Funding
A major source of CRG's funding is the Ford Foundation, which provided $420,000 in grants during 2005-2007.
See also
Bioethics
Genomics
References
External links
Appropriate technology organizations
Medical and health organizations based in Massachusetts
Biotechnology organizations
Genetics organizations
1983 establishments in Massachusetts
1983 establishments in the United States
Organizations established in 1983 | Council for Responsible Genetics | [
"Engineering",
"Biology"
] | 842 | [
"Biotechnology organizations"
] |
3,115,470 | https://en.wikipedia.org/wiki/Iron%28II%29%20fluoride | Iron(II) fluoride or ferrous fluoride is an inorganic compound with the molecular formula FeF2. It forms a tetrahydrate FeF2·4H2O that is often referred to by the same names. The anhydrous and hydrated forms are white crystalline solids.
Structure and bonding
Anhydrous FeF2 adopts the TiO2 rutile structure. As such, the iron cations are octahedral and fluoride anions are trigonal planar.
The tetrahydrate can exist in two structures, or polymorphs. One form is rhombohedral and the other is hexagonal, the former having a disorder.
Like most fluoride compounds, the anhydrous and hydrated forms of iron(II) fluoride feature high spin metal center. Low temperature neutron diffraction studies show that the FeF2 is antiferromagnetic. Heat capacity measurements reveal an event at 78.3 K corresponding to ordering of antiferromagnetic state.
Selected physical properties
FeF2 sublimes between 958 and 1178 K. Using Torsion and Knudsen methods, the heat of sublimation was experimentally determined and averaged to be 271 ± 2 kJ mole−1.
The following reaction is proposed in order to calculate the atomization energy for Fe+:
FeF2 + e → Fe+ + F2 (or 2F) + 2e
Synthesis and reactions
The anhydrous salt can be prepared by reaction of ferrous chloride with anhydrous hydrogen fluoride. It is slightly soluble in water (with solubility product Ksp = 2.36×10−6 at 25 °C) as well as dilute hydrofluoric acid, giving a pale green solution. It is insoluble in organic solvents.
The tetrahydrate can be prepared by dissolving iron in warm hydrated hydrofluoric acid and precipitating the result by addition of ethanol. It oxidizes in moist air to give, inter alia, a hydrate of iron(III) fluoride, (FeF3)2·9H2O.
Uses
FeF2 is used to catalyze some organic reactions.
Battery research
FeF2 has been investigated as a cathode material for both lithium-ion and fluoride-ion batteries. Unlike conventional metal oxides, which rely on an intercalation-based lithium storage mechanism, FeFX (x = 2, 3) operates via a complex conversion mechanism, resulting in higher energy density. Fluoride cathodes are stable up to 1000°C. Stability not only enhances safety and lowers the risk of thermal runaway.
FeFX exhibits distinctive phase evolution, intermediate phases, and morphological transformations during lithiation and delithiation. A stable lattice of fluoride anions is maintained throughout charge and discharge cycles, consistent with high cycling reversibility.
References
External links
National Pollutant Inventory - Fluoride and compounds fact sheet
Fluorides
Metal halides
Iron(II) compounds | Iron(II) fluoride | [
"Chemistry"
] | 648 | [
"Inorganic compounds",
"Fluorides",
"Metal halides",
"Salts"
] |
3,115,482 | https://en.wikipedia.org/wiki/Cobalt%28II%29%20fluoride | Cobalt(II) fluoride is a chemical compound with the formula (CoF2). It is a pink crystalline solid compound which is antiferromagnetic at low temperatures (TN=37.7 K) The formula is given for both the red tetragonal crystal, (CoF2), and the tetrahydrate red orthogonal crystal, (CoF2·4H2O). CoF2 is used in oxygen-sensitive fields, namely metal production. In low concentrations, it has public health uses.
CoF2 is sparingly soluble in water. The compound can be dissolved in warm mineral acid, and will decompose in boiling water. Yet the hydrate is water-soluble, especially the di-hydrate CoF2·2H2O and tri-hydrate CoF2·3H2O forms of the compound. The hydrate will also decompose with heat.
Like some other metal difluorides, CoF2 crystallizes in the rutile structure, which features octahedral Co centers and planar fluorides.
Preparation
Cobalt(II) fluoride can be prepared from anhydrous cobalt(II) chloride or cobalt(II) oxide in a stream of hydrogen fluoride:
CoCl2 + 2HF → CoF2 + 2HCl
CoO + 2HF → CoF2 + H2O
It is produced in the reaction of cobalt (III) fluoride with water.
The tetrahydrate cobalt(II) fluoride is formed by dissolving cobalt(II) in hydrofluoric acid. The anhydrous fluoride can be extracted from this by dehydration. Other synthesis can occur at higher temperatures. It has been shown that at 500 °C fluorine will combine with cobalt producing a mixture of CoF2 and CoF3.
Uses
Cobalt(II) fluoride can be used as a catalyst to alloy metals. It is also used for optical deposition, of which it tremendously improves optical quality. Cobalt(II) fluoride is available in most volumes in an ultra high purity composition. High purity compositions improve optical qualities and its usefulness as a standard.
Analysis
To analyze this compound, Cobalt (II) fluoride can be dissolved in nitric acid. The solution is then diluted with water until appropriate concentration for AA or ICP spectrophotometry for the cobalt. A small amount of salt can be dissolved in cold water and analyzed for fluoride ion by a fluoride ion-selective electrode or ion chromatography.
Chemical properties
CoF2 is a weak Lewis acid. Cobalt(II) complexes are usually octahedral or tetrahedral. As a 19-electron species it is a good reducing agent, fairly oxidizable into an 18-electron compound. Cobalt(II) fluoride can be reduced by hydrogen at a 300 °C.
References
External links
National Pollutant Inventory - Cobalt fact sheet
National Pollutant Inventory - Fluoride and compounds fact sheet
Fluorides
Metal halides
Cobalt(II) compounds | Cobalt(II) fluoride | [
"Chemistry"
] | 651 | [
"Inorganic compounds",
"Fluorides",
"Metal halides",
"Salts"
] |
3,115,543 | https://en.wikipedia.org/wiki/Erd%C5%91s%E2%80%93Szekeres%20theorem | In mathematics, the Erdős–Szekeres theorem asserts that, given r, s, any sequence of distinct real numbers with length at least (r − 1)(s − 1) + 1 contains a monotonically increasing subsequence of length r or a monotonically decreasing subsequence of length s. The proof appeared in the same 1935 paper that mentions the Happy Ending problem.
It is a finitary result that makes precise one of the corollaries of Ramsey's theorem. While Ramsey's theorem makes it easy to prove that every infinite sequence of distinct real numbers contains a monotonically increasing infinite subsequence or a monotonically decreasing infinite subsequence, the result proved by Paul Erdős and George Szekeres goes further.
Example
For r = 3 and s = 2, the formula tells us that any permutation of three numbers has an increasing subsequence of length three or a decreasing subsequence of length two. Among the six permutations of the numbers 1,2,3:
1,2,3 has an increasing subsequence consisting of all three numbers
1,3,2 has a decreasing subsequence 3,2
2,1,3 has a decreasing subsequence 2,1
2,3,1 has two decreasing subsequences, 2,1 and 3,1
3,1,2 has two decreasing subsequences, 3,1 and 3,2
3,2,1 has three decreasing length-2 subsequences, 3,2, 3,1, and 2,1.
Alternative interpretations
Geometric interpretation
One can interpret the positions of the numbers in a sequence as x-coordinates of points in the Euclidean plane, and the numbers themselves as y-coordinates; conversely, for any point set in the plane, the y-coordinates of the points, ordered by their x-coordinates, forms a sequence of numbers (unless two of the points have equal x-coordinates). With this translation between sequences and point sets, the Erdős–Szekeres theorem can be interpreted as stating that in any set of at least rs − r − s + 2 points we can find a polygonal path of either r − 1 positive-slope edges or s − 1 negative-slope edges. In particular (taking r = s), in any set of at least n points we can find a polygonal path of at least ⌊⌋ edges with same-sign slopes. For instance, taking r = s = 5, any set of at least 17 points has a four-edge path in which all slopes have the same sign.
An example of rs − r − s + 1 points without such a path, showing that this bound is tight, can be formed by applying a small rotation to an (r − 1) by (s − 1) grid.
Permutation pattern interpretation
The Erdős–Szekeres theorem may also be interpreted in the language of permutation patterns as stating that every permutation of length at least (r - 1)(s - 1) + 1 must contain either the pattern 12⋯r or the pattern s⋯21.
Proofs
The Erdős–Szekeres theorem can be proved in several different ways; surveys six different proofs of the Erdős–Szekeres theorem, including the following two.
Other proofs surveyed by Steele include the original proof by Erdős and Szekeres as well as those of , , and .
Pigeonhole principle
Given a sequence of length (r − 1)(s − 1) + 1, label each number ni in the sequence with the pair (ai, bi), where ai is the length of the longest monotonically increasing subsequence ending with ni and bi is the length of the longest monotonically decreasing subsequence ending with ni. Each two numbers in the sequence are labeled with a different pair: if and then , and on the other hand if then . But there are only (r − 1)(s − 1) possible labels if ai is at most r − 1 and bi is at most s − 1, so by the pigeonhole principle there must exist a value of i for which ai or bi is outside this range. If ai is out of range then ni is part of an increasing sequence of length at least r, and if bi is out of range then ni is part of a decreasing sequence of length at least s.
credits this proof to the one-page paper of and calls it "the slickest and most systematic" of the proofs he surveys.
Dilworth's theorem
Another of the proofs uses Dilworth's theorem on chain decompositions in partial orders, or its simpler dual (Mirsky's theorem).
To prove the theorem, define a partial ordering on the members of the sequence, in which x is less than or equal to y in the partial order if x ≤ y as numbers and x is not later than y in the sequence. A chain in this partial order is a monotonically increasing subsequence, and an antichain is a monotonically decreasing subsequence. By Mirsky's theorem, either there is a chain of length r, or the sequence can be partitioned into at most r − 1 antichains; but in that case the largest of the antichains must form a decreasing subsequence with length at least
Alternatively, by Dilworth's theorem itself, either there is an antichain of length s, or the sequence can be partitioned into at most s − 1 chains, the longest of which must have length at least r.
Application of the Robinson–Schensted correspondence
The result can also be obtained as a corollary of the Robinson–Schensted correspondence.
Recall that the Robinson–Schensted correspondence associates to each sequence a Young tableau P whose entries are the values of the sequence. The tableau P has the following properties:
The length of the longest increasing subsequence is equal to the length of the first row of P.
The length of the longest decreasing subsequence is equal to the length of the first column of P.
Now, it is not possible to fit (r − 1)(s − 1) + 1 entries in a square box of size (r − 1)(s − 1), so that either the first row is of length at least r or the last row is of length at least s.
See also
Longest increasing subsequence problem
References
External links
Ramsey theory
Permutation patterns
Theorems in discrete geometry
Articles containing proofs
Szekeres theorem
Theorems in discrete mathematics | Erdős–Szekeres theorem | [
"Mathematics"
] | 1,368 | [
"Discrete mathematics",
"Theorems in discrete geometry",
"Theorems in discrete mathematics",
"Combinatorics",
"Theorems in geometry",
"Mathematical problems",
"Articles containing proofs",
"Mathematical theorems",
"Ramsey theory"
] |
3,115,583 | https://en.wikipedia.org/wiki/Complexometric%20indicator | A complexometric indicator is an ionochromic dye that undergoes a definite color change in presence of specific metal ions. It forms a weak complex with the ions present in the solution, which has a significantly different color from the form existing outside the complex.
Complexometric indicators are also known as pM indicators.
Complexometric titration
In analytical chemistry, complexometric indicators are used in complexometric titration to indicate the exact moment when all the metal ions in the solution are sequestered by a chelating agent (most usually EDTA). Such indicators are also called metallochromic indicators.
The indicator may be present in another liquid phase in equilibrium with the titrated phase, the indicator is described as extraction indicator.
Some complexometric indicators are sensitive to air and are destroyed. When such solution loses color during titration, a drop or two of fresh indicator may have to be added.
Examples
Complexometric indicators are water-soluble organic molecules. Some examples are:
Calcein with EDTA for calcium
Patton-Reeder Indicator with EDTA for calcium with magnesium
Curcumin for boron, that forms Rosocyanine, although the red color change of curcumin also occurs for pH > 8.4
Eriochrome Black T for aluminium, cadmium, zinc, calcium and magnesium
Fast Sulphon Black with EDTA for copper
Hematoxylin for copper
Murexide for calcium and rare earths, but also for copper, nickel, cobalt, and thorium
Xylenol orange for gallium, indium and scandium
Redox indicators
In some settings, when the titrated system is a redox system whose equilibrium is influenced by the removal of the metal ions, a redox indicator can function as a complexometric indicator.
References
External links | Complexometric indicator | [
"Chemistry",
"Materials_science"
] | 366 | [
"Complexometric indicators",
"Chromism"
] |
3,115,609 | https://en.wikipedia.org/wiki/WorldWIT | WorldWIT was a global online discussion community for women in business and technology.
It was founded in 1999 as ChicWIT, in Chicago. ChicWIT was followed by MassWIT in Boston, NycWIT in New York City, and CapitolWIT in Washington, D.C. In October 2005 there were over 80 WorldWIT chapters in operation and over 40,000 members. Women (and a few men) used the daily WorldWIT newsletter to share business, technical, career, health, financial and life advice with one another.
WorldWIT was recognized in October 2004 as the Women's Business Organization of the Year, by the Stevie Awards Organization.
In March 2007, WorldWIT and its local city chapters were shut down. This was the announcement:
WorldWIT used L-Soft list serv technology and a robust website as the basis of its social networking platform. Bill Phillips designed and managed both the listserv and website. L-Soft published an online article featuring WorldWIT in 2005. See http://www.lsoft.com/news/qa-issue2-2005-eu.asp
External links
worldwit.org domain no longer exists
See https://web.archive.org/web/*/worldwit.org for a cached archive of WorldWIT's website.
See http://www.w3w3.com/WorldWIT-Radio/ for WorldWIT radio show.
American social networking websites
Organizations for women in science and technology
Internet properties established in 1999
Women's organizations based in the United States
1999 establishments in Illinois | WorldWIT | [
"Technology"
] | 340 | [
"Organizations for women in science and technology",
"Women in science and technology"
] |
3,115,697 | https://en.wikipedia.org/wiki/Copper%20gluconate | Copper gluconate is the copper salt of D-gluconic acid. It is an odorless light blue or blue-green crystal or powder which is easily soluble in water and insoluble in ethanol.
Uses
Dietary supplement to treat copper deficiency.
Ingredient of Retsyn, which was an ingredient of Certs breath mints.
Fertilizer deficiency corrector to treat lacks of this nutrient.
Side effects
The U.S. Institute of Medicine (IOM) sets tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of copper the adult UL is set at 10 mg/day.
Copper gluconate is sold as a dietary supplement to provide copper. The typical dose is 2.0 mg copper per day. This is one-fifth what the IOM considers a safe upper limit. Long-term intake at amounts higher than the UL may cause liver damage.
References
External links
Copper gluconate monograph at Drugs.com
Copper(II) compounds
Dietary supplements
Coordination complexes
Gluconates | Copper gluconate | [
"Chemistry"
] | 220 | [
"Coordination chemistry",
"Coordination complexes"
] |
3,115,869 | https://en.wikipedia.org/wiki/Tverberg%27s%20theorem | In discrete geometry, Tverberg's theorem, first stated by Helge Tverberg in 1966, is the result that sufficiently many points in Euclidean space can be partitioned into subsets with intersecting convex hulls. Specifically, for any positive integers d, r and any set of
points in d-dimensional Euclidean space there exists a partition of the given points into r subsets whose convex hulls all have a common point; in other words, there exists a point x (not necessarily one of the given points) such that x belongs to the convex hull of all of the subsets.
The partition resulting from this theorem is known as a Tverberg partition.
The special case r = 2 was proved earlier by Radon, and it is known as Radon's theorem.
Examples
The case d = 1 states that any 2r−1 points on the real line can be partitioned into r subsets with intersecting convex hulls. Indeed, if the points are x1 < x2 < ... < x2r < x2r-1, then the partition into Ai = {xi, x2r-i} for i in 1,...,r satisfies this condition (and it is unique).
For r = 2, Tverberg's theorem states that any d + 2 points may be partitioned into two subsets with intersecting convex hulls. This is known as Radon's theorem. In this case, for points in general position, the partition is unique.
The case r = 3 and d = 2 states that any seven points in the plane may be partitioned into three subsets with intersecting convex hulls. The illustration shows an example in which the seven points are the vertices of a regular heptagon. As the example shows, there may be many different Tverberg partitions of the same set of points; these seven points may be partitioned in seven different ways that differ by rotations of each other.
Topological Tverberg Theorem
An equivalent formulation of Tverberg's theorem is:Let d, r be positive integers, and let N := (d+1)(r-1). If ƒ is any affine function from an N-dimensional simplex ΔN to Rd, then there are r pairwise-disjoint faces of ΔN whose images under ƒ intersect. That is: there exist faces F1,...,Fr of ΔN such that and .They are equivalent because any affine function on a simplex is uniquely determined by the images of its vertices. Formally, let ƒ be an affine function from ΔN to Rd. Let be the vertices of ΔN, and let be their images under ƒ. By the original formulation, the can be partitioned into r disjoint subsets, e.g. ((xi)i in Aj)j in [r] with overlapping convex hull. Because f is affine, the convex hull of (xi)i in Aj is the image of the face spanned by the vertices (vi)i in Aj for all j in [r]. These faces are pairwise-disjoint, and their images under f intersect - as claimed by the new formulation.
The topological Tverberg theorem generalizes this formluation. It allows f to be any continuous function - not necessarily affine. But, currently it is proved only for the case where r is a prime power:Let d be a positive integer, and let r be a power of a prime number. Let N := (d+1)(r-1). If ƒ is any continuous function from an N-dimensional simplex ΔN to Rd, then there are r pairwise-disjoint faces of ΔN whose images under ƒ intersect. That is: there exist faces F1,...,Fr of ΔN such that and .
Proofs
The topological Tverberg theorem was proved for prime by Barany, Shlosman and Szucs. Matousek presents a proof using deleted joins.
The theorem was proved for a prime-power by Ozaydin, and later by Volovikov and Sarkaria.
See also
Rota's basis conjecture
References
Further reading
Theorems in convex geometry
Theorems in discrete geometry
Geometric transversal theory
Convex hulls | Tverberg's theorem | [
"Mathematics"
] | 890 | [
"Geometric transversal theory",
"Theorems in convex geometry",
"Theorems in discrete mathematics",
"Basic concepts in set theory",
"Families of sets",
"Theorems in geometry",
"Theorems in discrete geometry"
] |
3,115,920 | https://en.wikipedia.org/wiki/Urca%20process | In astroparticle physics, an Urca process is a reaction which emits a neutrino and which is assumed to take part in cooling processes in neutron stars and white dwarfs. The process was first discussed by George Gamow and Mário Schenberg while they were visiting a casino named Cassino da Urca in Urca, Rio de Janeiro. As Gamow recounts in his autobiography, the name was chosen in part to commemorate the gambling establishment where the two physicists had first met, and "partially because the Urca Process results in a rapid disappearance of thermal energy from the interior of a star, similar to the rapid disappearance of money from the pockets of the gamblers on the Casino de Urca." In Gamow's South Russian dialect, urca () can also mean a robber or gangster.
The direct Urca processes are the simplest neutrino-emitting processes and are thought to be central in the cooling of neutron stars. They have the general form
{|
| B || || || → || B || + || || + || ,
|------------------------------------------
| B || + || || → || B || + ||,
|}
where B and B are baryons, is a lepton, and (and ) are (anti-)neutrinos. The baryons can be nucleons (free or bound), hyperons like , and , or members of the isobar. The lepton is either an electron or a muon.
The Urca process is especially important in the cooling of white dwarfs, where a lepton (usually an electron) is absorbed by the nucleus of an ion and then convectively carried away from the core of a star. Then, a beta decay occurs. Convection then carries the element back into the interior of the star, and the cycle repeats many times. Because the neutrinos emitted during this process are unlikely to be reabsorbed, this is effectively a cooling mechanism for white dwarfs.
The process can also be essential in the cooling of neutron stars. If a neutron star contains a central core in which the direct Urca-process is operative, the cooling timescale shortens by many orders of magnitude.
References
Concepts in astrophysics | Urca process | [
"Physics"
] | 513 | [
"Concepts in astrophysics",
"Astrophysics"
] |
3,115,993 | https://en.wikipedia.org/wiki/Environmental%20stress%20screening | Environmental stress screening (ESS) refers to the process of exposing a newly manufactured or repaired product or component (typically electronic) to stresses such as thermal cycling and vibration in order to force latent defects to manifest themselves by permanent or catastrophic failure during the screening process. The surviving population, upon completion of screening, can be assumed to have a higher reliability than a similar unscreened population.
Overview
Developed to help electronics manufacturers detect product defects and production flaws, ESS is widely used in military and aerospace applications, less so for commercial products. The tests need not be elaborate, for example, switching an electronic or electrical system on and off a few times may be enough to catch some simple defects that would otherwise be encountered by the end user very soon after the product was first used. Tests typically include the following:
Temperature variations
Vibration tests
Pressure
Flexibility tests
ESS can be performed as part of the manufacturing process or it can be used in new product qualification testing.
An ESS system usually consists of a test chamber, controller, fixturing, interconnect and wiring, and a functional tester. These systems can be purchased from a variety of companies in the environmental test industry.
The stress screening from this process will help find infant mortality in the product. Finding these failures before the product reaches the customer yields better quality and lower warranty expenses. Associated military terminology includes an operational requirements document (ORD) and ongoing reliability testing (ORT).
Standardized Definitions and Methods
The following is extracted from a paper on ESS testing prepared by the U.S. Air Force to provide standardized definitions and methods.
Introduction
The purpose of this paper is to provide standardized definitions and a roadmap of test processes for the Environmental Stress Screening (ESS) of replacement and repaired components used on Air Force systems. The term “component” is used interchangeably with the term “unit” and includes Line-replaceable unit (LRU) and sub-units (SRU). A component selected for testing is a Unit Under Test (UUT). Operational Safety, Suitability, and Effectiveness (OSS&E) policy and instructions require consistency in the disciplined engineering process used to ensure that activities such as maintenance repairs and part substitutions do not degrade system or end-item baselined characteristics over their operational life. Baselined characteristics are highly dependent on reliability, which is verified and maintained by ESS testing. OSS&E policy and instructions also require consistent engineering processes to ensure manufacturing and repair entities are accountable for delivering quality products, and to provide selection and qualification criteria for new sources of supply. Determinations of product quality and source capabilities usually require ESS testing. While considerable information concerning ESS methods and procedures is available including United States Military Standards, handbooks, guides, and the original equipment manufacturer's test plans, often these publications use differing and confusing definitions for the testing phases where ESS is applied. Lengthy explanations were needed to clarify contract clauses citing these publications. This paper ensures testing requirements are uniformly applied and clearly understood in writing source qualification requirements and contracts.
Visual Inspection
Purpose
To ensure that good workmanship has been employed and that the UUT is free of obvious physical defects.
Method
Visually inspect UUT before and after each manufacturing, repair, and test operation.
Verify proper labeling, weight, and dimensions.
With the unaided eye, inspect all accessible areas of the UUT.
Under 10X minimum magnification, inspect all critical surfaces and interfaces of the UUT.
Pass/Fail Criteria
Workmanship shall meet the applicable standards including T.O. 00-25-234 and shall be free of obvious physical defects. A unit that exhibits any sign that a part is stressed beyond its design limit (cracked circuit boards, loose connectors and/or screws, bent clamps and/or screws, worn parts, etc.) is considered to have failed even if the UUT passes the Functional Testing.
Functional Testing
Purpose
Done before, during, and after ESS testing to verify that the UUT is functioning within design tolerances.
Method
Applying an input signal or stimulus and measuring the output.
Pass/Fail Criteria
Output responses/signals must be within technical data specifications, and the UUT must operate satisfactorily in the next higher assembly.
Environmental Stress Screening (ESS)
Purpose
Testing at the physical environmental conditions (shock, vibration, temperature, altitude, humidity, etc.) that simulate those encountered over the operational life of the component. Random vibration and temperature cycling have proven to be the most successful forms of ESS in terms of effective flaw precipitation.
Method
A stress profile is developed and applied to the UUT. The profile simulates the environmental conditions encountered during transportation, storage, handling, and operational use phases. The UUT is configured to match the phase, e.g. transportation shocks are applied with the UUT in the shipping container, operational use temperature cycles are applied with the UUT operating.
Pass/Fail Criteria
The UUT (Unit Under Test) must pass Functional Testing and Visual Inspection before, during, and after ESS.
Qualification ESS
The testing of a production-representative unit to demonstrate that the design, manufacturing, assembly, and repair processes have resulted in hardware that conforms to the specification. Satisfactory completion of Qualification Testing denotes readiness for further stages of testing. Limited flight testing may be acceptable before completion of all phases of Qualification Testing.
Production Unit Qualification Testing
Purpose: Done for qualification of a new manufacturer, design, process, or facility to ensure the adequacy and suitability of the design to reliably operate during and after exposure to environmental stresses that exceed operational environment predictions by a prescribed margin.
Method: Per Mil-Std-810G for LRUs and SRUs, per Mil-Std-202G for electronic piece parts, per Mil-Std-1540 for space systems, and per Mil-Std-883H for microelectronic devices. EMI/RFI Testing is usually included in ESS Qualification Testing and requires application of MIL-STD 461E. These Military Standards require tailoring. Mil-HDBKs-340, 343, 344 and 2164 provide detailed guidance. Sequence of First Production Article testing: Visual Inspection and Functional – Preconditioning – Acceptance ESS – Acceptance Reliability – Visual Inspection & Functional – Qualification ESS – Visual Inspection & Functional –Qualification Reliability – Visual Inspection & Functional.
Note: Qualification Testing usually includes ‘aggravated’ ESS testing, i.e. test to actual environmental levels and duration plus a margin (typically 10 °C, 6 dB). Adding margin is required due to the statistically small sample size and uncertainties in actual environmental levels. Since this is a destructive test, the UUT shall never be fielded in operational systems.
Note: Must do Acceptance Testing including Pre-Conditioning first. This is because these tests are done on all production units and so become parts of the environmental stress profile.
Note: Another manufacturer (second-source) building the same unit or a replacement unit that is intended as a form-fit-and-function replacement for the original unit or unit sub-assembly must be qualified to specifications equivalent to those used for the original source.
Repaired Unit Qualification Testing
Purpose: Performed on First Repaired Article or Pre-Qualification Repaired Article units to qualify a new repair source or repair method. It is also performed to evaluate substitute piece parts.
Method: If the repair parts and processes are equivalent to the original manufacturing parts and processes, then use the Repaired Unit Acceptance Test performed by the contractor, followed by Government inspection and operation in the next higher assembly. If the parts and processes are not known to be equivalent, then use applicable areas of the Production Unit Qualification Testing. Sequence of PreQual Repaired Article / First Repaired Article testing: Visual Inspection & Functional – Preconditioning – Acceptance ESS – Visual Inspection & Functional – Gov't Inspection & Functional.
Note: Due to Diminishing Manufacturing Sources (DMS), substitutions of piece parts are often necessary. Substitute parts that appear under ambient test bench conditions to function like the original parts can exhibit unsatisfactory performance in the operational environment.
Qualification by Similarity. Qualification of a replacement or repaired unit by similarity to the original unit requires that the units are essentially identical. In addition, the replacement unit must have previously been qualified by testing to environmental and operational performance requirements meeting or exceeding the environmental and operational requirements of the original unit.
Acceptance ESS
Formal tests conducted to demonstrate acceptability of the individual unit for delivery. They demonstrate performance to purchase specification requirements and act as quality control screens to detect deficiencies of workmanship and materials. The successful completion of such tests denotes acceptance of the unit by the procurement agency.
Production Unit Acceptance Testing
Purpose: Done on 100% of new units to detect workmanship and process errors. Inspection of some microelectronic devices is destructive so lot sampling is used for acceptance testing (see paragraph 8.3.2).
Method: Tailored down from applicable Production Qualification Test but done to workmanship levels, no more severe than actual environmental levels and of shortened duration. Usually these tests are structured to include the Pre-Conditioning and Reliability Acceptance Testing requirements. Sequence for Components testing: Visual Inspection & Functional – Preconditioning – Acceptance ESS – Acceptance Reliability – Visual Inspection & Functional.
Note: Production Unit Acceptance Testing performance data is also used to evaluate "in-family" performance. While a UUT may meet all other Acceptance Test pass/fail criteria, results which deviate significantly from other units within the production lot shall require rejection of that unit.
Repaired Unit Acceptance Testing
Purpose: Performed on 100% of repaired units to detect workmanship and process errors.
Method: Tailored down from applicable Production Acceptance Tests. To maintain the specified reliability criteria, Pre-Conditioning Testing should be included if the repair parts are not pre-conditioned or the repair workmanship can be expected to induce failures. Sequence for Components testing: Visual Inspection & Functional – Preconditioning – Acceptance ESS – Visual Inspection & Functional.
Note: Test levels are low and not destructive so testing may be repeated for test failures and subsequent repairs without significantly aging the UUT.
Note: Types and levels of testing may have to be increased if infant mortality failures are occurring in operational use. Conversely, if a statistically significant sampling demonstrates that infant mortality failures are not occurring, ESS tests may be reduced or eliminated. Functional Testing is still required.
Note: Testing must strike a balance between the probability that the repairs have induced a defect, and the probability that the testing can detect that defect. For example, a reduced number of temperature cycles has a lower probability of detecting a defect, but may be appropriate if the repair is minor and has little risk of inducing a defect.
Note: Repaired Unit Acceptance Testing performance data is also used to evaluate "in-family" performance. While a UUT may meet all other Acceptance Test pass/fail criteria, results which deviate significantly from other repaired units or from the original Production Unit Acceptance Test data shall require rejection of the UUT.
Reliability ESS
This should be part of the Qualification and Acceptance ESS when verification of reliability is required.
Reliability Qualification Testing
Purpose: Done on the production qualification UUT to demonstrate life-cycle compliance with the reliability specifications per Mil-Std-781, and the original manufacturer's development specifications.
Method: Use Mil-Hdbk-781A. The UUT is usually tested to actual environmental levels, but margin is added if accelerated aging is required.
Note: Must do Acceptance Testing including Pre-Conditioning first. This is because these tests are done on all production units and so become parts of the environmental stress profile.
Note: The presence of redundancy in the design is not reason to eliminate reliability tests. Redundancy is used to compensate for any unknown and untested failure modes, and for damage tolerance. Redundancy only increases reliability by a small amount.
Reliability Acceptance Testing
Purpose: Done on all production units to find any unit with reliability degradation due to daily variations in the production process and workmanship.
Method: Vibration (typically 0.04 G2/Hz for 5 minutes/axis) and temperature for 3+ cycles, last one failure-free.
Note: Usually only done on high reliability (3-sigma) and safety of flight items.
Pre-Conditioning Testing. Also called Burn-In Testing
Purpose: Done on all active unit LRUs, SRUs, and piece parts (production, spare, and repair) to find ‘infant mortality’ of parts and workmanship.
Method: per Mil-Std-750D, Mil-Std-883E, and Mil-Std-202G.
Note: Most mil-spec piece parts have not been pre-conditioned by the part manufacturer.
UUT Categories
Passive Unit
Examples: chassis, antenna coupler, optics without moving parts, wiring harness.
Note: Requires Qualification ESS of the design and processes, usually in the next higher assembly. Acceptance Testing is limited to Visual Inspection and Operational Testing in the next higher assembly.
Active Unit
Examples: PC board with solid state devices, electric motor, cathode ray tube, pressure vessel.
Note: Usually requires Qualification ESS and Acceptance ESS.
One-Shot and Limited Use Devices
Examples: explosive, rocket propellant, gas generator, squib, battery.
Method: Qualification ESS is by exposure to qualification environmental levels, then operated to demonstrate capacity plus a margin. Acceptance ESS is typically done on 10% of the production lot (but not less than 10 units) by exposure to qualification environmental levels, then operated to demonstrate capacity plus a margin. Failure of one UUT requires rejection of the production lot. For explosive devices, test requirements and methods are tailored from MIL-HDBK-1512 and NATO AOP-7. For batteries, guidance on test requirements is in RCC-Doc-319-99.
Note: Surveillance Testing is a periodic repeat of the Acceptance Testing using trending or accelerated aging to authorize shelf life extensions. Trending involves frequent sampling and comparison to previous results to predict degradation. Accelerated aging involves stimulating known failure modes to detect degradation.
First Production Article
This is the UUT for Qualification ESS (typically three UUT are required). The UUT must be representative of the design, production line processes, materials, and workmanship.
First Repaired Article
Also called First Article. This is the UUT (typically four are required) that demonstrates that the repair source has the capability and processes to perform a satisfactory repair.
Pre-Qualification Article
Pre-Qualification Production Article. Also called Pre-production Article. This is the UUT used for program risk reduction and to qualify key processes, technologies, etc.
Pre-Qualification Repaired Article. Also called Qual Article. This is the UUT (typically two are required) repaired by a potential repair contractor to meet, in part, the criteria to be on a Qualified Bidders List.
Tailoring
Tailoring is the formal engineering task of using existing technical data (requirements, standards, specifications, test plans, etc.) and selecting or modifying applicable areas to meet the requirements unique to the type of unit undergoing test. Non-applicable requirements are deleted. Other requirements may be added due to changes in Federal standards, identification of new hazards, modifications to the item, or changes in the mission/ESS profile. All areas of non-compliance with the technical data shall be identified by the contractor and a Requirements Tailoring Request (RTR) shall be submitted to the Government for each area. The RTR shall include thorough justification. Only the Government Engineering Authority for the component can accept an RTR.
Specifications and Standards Tailoring
Tailoring generally is to select the applicable areas, best test methods, or for use of an equivalent requirement.
Test Plan Tailoring
Tailoring generally is to change the test levels and durations, sequence of tests, or reporting requirements. Tailoring shall also identify any test requirements that are to be accomplished through analysis, similarity, or inspection.
MIC, Waiver, and Deviation
Each RTR shall be classified as a MIC, Waiver, or Deviation.
MIC. An RTR that still meets the intent of the specified technical data is classified as a Meets Intent Compliance (MIC).
Waiver. If an RTR potentially increases the safety hazards, it is classified as a Waiver and must also be accepted by the cognizant Government and contractor safety offices. The intent of a Waiver is to grant temporary approval to proceed while the hazard is being corrected. A series of unlikely, unrelated simultaneous failures is not considered a hazard.
Deviation. An RTR that does not increase safety hazards and is not a MIC is classified as a Deviation.
Relevant standards
See also
Accelerated aging
Environmental chamber
Environmental tests
Failure analysis
United States Military Standard
MIL-STD-810 "Department of Defense Test Method Standard for Environmental Engineering Considerations and Laboratory Tests"
Highly accelerated stress screen
Highly accelerated life test
Notes
Environmental testing
Hardware testing | Environmental stress screening | [
"Engineering"
] | 3,438 | [
"Environmental testing",
"Reliability engineering"
] |
3,116,066 | https://en.wikipedia.org/wiki/Colure | Colure, in astronomy, is either of the two principal meridians of the celestial sphere. The term is now rarely used and may be considered obsolete.
Equinoctial colure
The equinoctial colure is the meridian or great circle of the celestial sphere which passes through the celestial poles and the two equinoxes: the first point of Aries and the first point of Libra. It is the great circle consisting of all points on the celestial sphere with Right Ascension equal to 0 hours or 12 hours (equivalent to RA 0° / 180°).
The equinoctial colure passes through the following constellations:
Solstitial colure
The solstitial colure is the meridian or great circle of the celestial sphere which passes through the poles and the two solstices: the first point of Cancer and the first point of Capricorn. It is the great circle consisting of all points on the celestial sphere with Right Ascension equal to 6 hours or 18 hours (equivalent to RA 90° / 270°).
The solstitial colure passes through the following constellations:
See also
Celestial coordinate system
Ecliptic
Celestial sphere
Right ascension
Equinox
Solstice
References
Kaler, Jim. "Pi Aurigae." Pi Aurigae. N.p. 22 Feb. 2008. Web.
Astronomical coordinate systems
Solstices | Colure | [
"Astronomy",
"Mathematics"
] | 281 | [
"Time in astronomy",
"Astronomy stubs",
"Astronomical coordinate systems",
"Solstices",
"Coordinate systems"
] |
3,116,075 | https://en.wikipedia.org/wiki/Constant%20speed%20drive | A constant speed drive (CSD) also known as a constant speed generator, is a type of transmission that takes an input shaft rotating at a wide range of speeds, delivering this power to an output shaft that rotates at a constant speed, despite the varying input. They are used to drive mechanisms, typically electrical generators, that require a constant input speed.
The term is most commonly applied to hydraulic transmissions found in the accessory drives of gas turbine engines, such as aircraft jet engines. On modern aircraft, the CSD is often combined with a generator into a single unit known as an integrated drive generator (IDG).
Mechanism
CSDs are mainly used on airliner and military aircraft jet engines to drive the alternating current (AC) electrical generator. In order to produce the proper voltage at a constant AC frequency, usually three-phase 115 VAC at 400 Hz, an alternator needs to spin at a constant specific speed (typically 6,000 RPM for air-cooled generators). Since the jet engine gearbox speed varies from idle to full power, this creates the need for a constant speed drive (CSD). The CSD takes the variable speed output of the accessory drive gearbox and hydro-mechanically produces a constant output RPM.
Different systems have been used to control the alternator speed. Modern designs are mostly hydrokinetic, but early designs often took advantage of the bleed air available from the engines. Some of these were mostly mechanically powered, with an air turbine to provide a vernier speed adjustment. Others were purely turbine-driven.
Integrated drive generator
On aircraft such as the Airbus A310, Airbus A320 family, Airbus A320neo, Airbus A330, Airbus A330neo, Airbus A340, Boeing 737 Next Generation, 747, 757, 767 and 777, an integrated drive generator (IDG) is used. This unit is simply a CSD and an oil cooled generator inside the same case. Troubleshooting is simplified as this unit is the line-replaceable electrical generation unit on the engine.
Manufacturers
Collins Aerospace (formerly UTC Aerospace Systems (formerly Hamilton Sundstrand)) is an American manufacturer of CSD and IDG units.
Alternatives
A variable-speed constant-frequency (VSCF) generator can be used to provide AC power using an electronic tap converter.
Variable Frequency Starter Generator (VFSG) used primarily on the Boeing 787 are both used for electric start and electric generation.
An electronic Power inverter can take a variable frequency and voltage AC or variable voltage DC input, e.g. from a permanent magnet generator, and convert it to fixed RMS voltage and frequency AC.
See also
Centrifugal governor
Continuously variable transmission
References
Jet engine technology
Aircraft components
Aerospace engineering
Vehicle technology | Constant speed drive | [
"Engineering"
] | 562 | [
"Vehicle technology",
"Mechanical engineering by discipline",
"Aerospace engineering"
] |
3,116,283 | https://en.wikipedia.org/wiki/Rho2%20Cephei | {{DISPLAYTITLE:Rho2 Cephei}}
Rho2 Cephei, Latinized from ρ2 Cephei, or simply ρ Cephei, is a solitary star in the northern constellation of Cepheus. With an apparent visual magnitude of 5.50, it is faintly visible to the naked eye, forming an optical pair with Rho1 Cephei. Based upon an annual parallax shift of 13.31 mas as seen from the Earth, it is located about 245 light years from the Sun.
Rho2 Cephei is an A-type main sequence star with a stellar classification of A3 V, estimated to be 85 million years old. It has a high rate of rotation, showing a projected rotational velocity of 133 km/s. The effective temperature of its photosphere is and its bolometric luminosity, the total amount of radiation it emits at all wavelengths, is .
References
Cephei, Rho2
Cepheus (constellation)
Cephei, Rho2
Durchmusterung objects
Cephei, 29
213798
111056
8591 | Rho2 Cephei | [
"Astronomy"
] | 236 | [
"Constellations",
"Cepheus (constellation)"
] |
3,116,296 | https://en.wikipedia.org/wiki/Eta%20Lyrae | Eta Lyrae, a name Latinized from η Lyrae, is a likely binary star system in the northern constellation of Lyra. It has the traditional name Aladfar and is faintly visible to the naked eye with an apparent visual magnitude of 4.43. The system is located at a distance of approximately 1,390 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −8 km/s.
Nomenclature
η Lyrae (Latinised to Eta Lyrae) is the binary star's Bayer designation. Its designation as the A component of a double star, and of its two constituents as the Aa and Ab components, derives from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
'BD +38 3491' is the 'B' component's designation in the Bonner Durchmusterung astrometric star catalogue.
Eta Lyrae bore the traditional name Aladfar, from the Arabic الأظفر al-ʼuẓfur "the talons (of the swooping eagle)", a name it shares with Mu Lyrae (though the latter is typically spelled Alathfar). The Working Group on Star Names (WGSN) has approved the name Aladfar for the Aa component of the system (the primary component of Eta Lyrae).
Properties
The suspected radial velocity variations of this star in 1938 led to it being incorrectly classified as a Beta Cephei-type star, although there was some early disagreement about the variation. In 1951, J. A. Pearce and R. M. Petrie also noted that the star appeared to have a variable radial velocity. It was announced as a binary system by H. A. Abt and S. G. Levy in 1978, who listed it as a single-lined spectroscopic binary, albeit with marginal elements. The putative components have an orbital period of 56 days with an eccentricity (ovalness) of 0.5 and a small radial velocity variation of .
The visible component of this system is a massive B-type star with a stellar classification of B2.5IV. It is around 23 million years old with ten times the mass of the Sun and a low rotational velocity. The star is radiating around 19,095 times the luminosity of the Sun from its photosphere at an effective temperature of 19,525 K. A magnetic field has been detected with an average quadratic field strength of .
The magnitude 8.58 star BD +38 3491 forms a visual companion to this pair. It is designated Eta Lyrae B in the Washington Double Star Catalog, and is located at an angular separation of along a position angle of 81°, as of 2017.
References
B-type subgiants
Spectroscopic binaries
Lyra
Lyrae, Eta
Durchmusterung objects
Lyrae, 20
180163
094481
7298
Aladfar | Eta Lyrae | [
"Astronomy"
] | 629 | [
"Lyra",
"Constellations"
] |
3,116,297 | https://en.wikipedia.org/wiki/Bockstein%20homomorphism | In homological algebra, the Bockstein homomorphism, introduced by , is a connecting homomorphism associated with a short exact sequence
of abelian groups, when they are introduced as coefficients into a chain complex C, and which appears in the homology groups as a homomorphism reducing degree by one,
To be more precise, C should be a complex of free, or at least torsion-free, abelian groups, and the homology is of the complexes formed by tensor product with C (some flat module condition should enter). The construction of β is by the usual argument (snake lemma).
A similar construction applies to cohomology groups, this time increasing degree by one. Thus we have
The Bockstein homomorphism associated to the coefficient sequence
is used as one of the generators of the Steenrod algebra. This Bockstein homomorphism has the following two properties:
,
;
in other words, it is a superderivation acting on the cohomology mod p of a space.
See also
Bockstein spectral sequence
References
.
Algebraic topology
Homological algebra | Bockstein homomorphism | [
"Mathematics"
] | 220 | [
"Mathematical structures",
"Algebraic topology",
"Fields of abstract algebra",
"Topology",
"Category theory",
"Homological algebra"
] |
3,116,306 | https://en.wikipedia.org/wiki/Mu%20Lyrae | μ Lyrae, Latinized as Mu Lyrae, is a solitary star in the northern constellation Lyra. It has the traditional name Alathfar , from the Arabic الأظفار al-ʼaẓfār "the talons (of the swooping eagle)", a name it shares with Eta Lyrae (though the latter is spelled "Aladfar" by the IAU). This white-hued object is visible to the naked eye as faint point of light with an apparent visual magnitude of 5.11. It is located approximately 412 light years distant from the Sun based on parallax, but is drifting closer with a radial velocity of −24 km/s.
This object has evolved off the main sequence, becoming a subgiant with a stellar classification of A0 IV. It has a fairly high rate of spin, showing a projected rotational velocity of 165 km/s. This is giving the star an equatorial bulge that is an estimated 17% larger than the polar radius. The star has three times the mass of the Sun and about 4.5 times the Sun's radius. It is radiating 200 times the Sun's luminosity from its photosphere at an effective temperature of 9,016 K.
References
External links
A-type subgiants
Lyra
Lyrae, Mu
Durchmusterung objects
Lyrae, 02
169702
090191
6903
Alathfar | Mu Lyrae | [
"Astronomy"
] | 300 | [
"Lyra",
"Constellations"
] |
3,116,318 | https://en.wikipedia.org/wiki/Cartan%20formula | In mathematics, Cartan formula can mean:
one in differential geometry: , where , and are Lie derivative, exterior derivative, and interior product, respectively, acting on differential forms. See interior product for the detail. It is also called the Cartan homotopy formula or Cartan magic formula. This formula is named after Élie Cartan.
one in algebraic topology, which is one of the five axioms of Steenrod algebra. It reads:
.
See Steenrod algebra for the detail. The name derives from Henri Cartan, son of Élie.
Footnotes
See also
List of things named after Élie Cartan | Cartan formula | [
"Mathematics",
"Engineering"
] | 130 | [
"Theorems in differential geometry",
"Mathematical theorems",
"Mathematical structures",
"Tensors",
"Algebraic topology",
"Theorems in topology",
"Differential forms",
"Fields of abstract algebra",
"Topology",
"Category theory",
"Theorems in geometry",
"Mathematical identities",
"Mathematica... |
3,116,328 | https://en.wikipedia.org/wiki/Xi%20Cephei | Xi Cephei (ξ Cephei, abbreviated Xi Cep, ξ Cep) is a multiple star system in the constellation of Cepheus. It is approximately 86 light-years from Earth.
It consists of two binary stars, designated Xi Cephei A and B, together with a more distant companion, Xi Cephei C. A's two components are themselves designated Xi Cephei Aa (officially named Kurhah , the traditional name of the system) and Ab.
Nomenclature
ξ Cephei (Latinised to Xi Cephei) is the system's Bayer designation. The designations of the three constituents as ξ Cephei A, B and C, and those of A's components - ξ Cephei Aa and Ab - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
Xi Cephei bore the traditional names Kurhah, Alkirdah or Al Kirduh, the name coming from Qazvini who gave Al Ḳurḥaḥ (القرحة al-qurhah), an Arabic word Ideler translated as a white spot, or blaze, in the face of a horse. Allen indicates that Ideler felt this was not a proper name for a star, and suggested the name Al Ḳirdah (ألقردة al qírada "the Ape"). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name Kurhah for the component Xi Cephei Aa on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning Celestial Hook, refers to an asterism consisting of Xi Cephei, 4 Cephei, HD 194298, Eta Cephei, Theta Cephei, Alpha Cephei, 26 Cephei, Iota Cephei and Omicron Cephei. Consequently, the Chinese name for Xi Cephei itself is (, ).
Properties
Xi Cephei A is a double-lined spectroscopic binary system with an orbital period of 810.9 days and an eccentricity of 0.46. The primary, component Aa, is a chemically peculiar Am star, a probable subgiant with an apparent magnitude of +4.29. Eight arcseconds away, Xi Cephei B is another spectroscopic binary. Xi Cephei C is a 13th magnitude star nearly two arcminutes away.
References
Cepheus (constellation)
Cephei, Xi
A-type main-sequence stars
Libertas
Cephei, 17
209790 1
108917
BD+63 1802
8417
Spectroscopic binaries
Am stars
F-type main-sequence stars
F-type subgiants | Xi Cephei | [
"Astronomy"
] | 627 | [
"Constellations",
"Cepheus (constellation)"
] |
3,116,343 | https://en.wikipedia.org/wiki/Nu%20Capricorni | Nu Capricorni or ν Capricorni is a binary star system in the southern constellation of Capricornus. It is visible to the naked eye with an apparent visual magnitude of +4.76.
Attributes
The star system is 6.6 degrees north of the ecliptic and so is within the margin of occultations of few if any planets but is well within that of the Moon. The celestial latitude of either of the Alpha Capricorni main stars is about 6.93 degrees by comparison. The system is calculated to be a distance of 253 light-years from the Sun based on parallax.
The two components are designated Nu Capricorni A and B. Component A is formally named Alshat , the traditional name for the system)
The primary, component A, is a blue-white hued B-type main-sequence or subgiant star with an apparent magnitude of +4.77. Component B is a magnitude 11.8 star at an angular separation of 54.1 arcseconds from the primary. Gaia Data Release 2 shows the companion to be much further away from Earth.
Nomenclature
ν Capricorni, Latinised to Nu Capricorni, is the system's Bayer designation. The designations of the two components as Nu Capricorni A and B derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
The system bore the traditional name Alshat, from the Arabic الشاة aš-šā[t], meaning 'the sheep' that was to be slaughtered by the adjacent Beta¹ Capricorni (Dabih). In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name Alshat for the component Nu Capricorni A on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.
References
B-type main-sequence stars
Binary stars
Alshat
Capricorni, Nu
Capricornus
Durchmusterung objects
Capricorni, 08
193432
100310
7773 | Nu Capricorni | [
"Astronomy"
] | 477 | [
"Capricornus",
"Constellations"
] |
3,116,357 | https://en.wikipedia.org/wiki/Delta%20Draconis | Delta Draconis (δ Draconis, abbreviated Delta Dra, δ Dra), formally named Altais , is a yellow star in the constellation of Draco. It has an apparent visual magnitude of 3.0, making it easily visible to the naked eye. Based on parallax measurements obtained by the Gaia mission, it is approximately from the Sun.
Nomenclature
δ Draconis (Latinised to Delta Draconis) is the star's Bayer designation.
It bore the traditional names Aldib, Altais (the goat) and Nodus Secundus. The title Altais was derived from Arabic Al Tāis "the Goat", the association of this star, along with Pi Draconis, Rho Draconis and Epsilon Draconis (Tyl). According to a 1971 NASA catalog of stars, Al Tāis or Tais were the title for three stars : Delta Draconis as Altais, Pi Draconis as Tais I and Rho Draconis as Tais II (exclude Epsilon Draconis). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name Altais for this star on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning Celestial Kitchen or Heaven's Kitchen, refers to an asterism consisting of Delta Draconis, Sigma Draconis, Epsilon Draconis, Rho Draconis, 64 Draconis and Pi Draconis. Consequently, the Chinese name for Delta Draconis itself is (, ).
Properties
Delta Draconis is a giant star with a stellar classification of G9 III. This indicates that it has exhausted the supply of hydrogen at its core and entered a later stage in its evolution. Around 1.7 billion years old, Delta Draconis has expanded to 10.5 times the Sun's radius and is radiating 59 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 4,873 K. At this temperature, it is giving off the yellow-hued glow of a G-type star. With a mass 1.7 times that of the Sun, this star will end its life as a white dwarf.
Pole star
Delta Draconis is the northern pole star of Ceres, lying 1.5 degrees from the true pole.
References
Draco (constellation)
Draconis, Delta
G-type giants
Altais
094376
Draconis, 57
180711
Durchmusterung objects
7310 | Delta Draconis | [
"Astronomy"
] | 550 | [
"Constellations",
"Draco (constellation)"
] |
3,116,364 | https://en.wikipedia.org/wiki/Xi%20Geminorum | Xi Geminorum (ξ Geminorum, abbreviated Xi Gem, ξ Gem), formally named Alzirr , is a star in the zodiac constellation of Gemini. It forms one of the four feet of the outline demarcating the Gemini twins. The star has an apparent visual magnitude of 3.35, which is bright enough for it to be seen with the naked eye. From stellar parallax measurements, its distance from the Sun can be estimated as .
Nomenclature
ξ Geminorum (Latinised to Xi Geminorum) is the star's Bayer designation.
It bore the traditional name of Al Zirr or Alzirr, from the Arabic الزِرّ al-zirr "the button". In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name Alzirr for this star on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.
This star, along with Gamma Geminorum (Alhena), Mu Geminorum, Nu Geminorum and Eta Geminorum were al-hanʽah "the brand" (on the neck of the camel). They also were associated in al-nuḥātai, the dual form of al-nuḥāt, "the camel's hump".
In Chinese, (), meaning Well (asterism), refers to an asterism consisting of Xi Geminorum, Mu Geminorum, Nu Geminorum, Gamma Geminorum, Epsilon Geminorum, 36 Geminorum, Zeta Geminorum and Lambda Geminorum. Consequently, Xi Geminorum itself is known as (, .)
Properties
Although generally considered a single star, there is some evidence that Xi Geminorum may instead be a spectroscopic binary system consisting of two component stars of equal mass.
Xi Geminorum has a stellar classification of F5 IV-V, which is subgiant star that is in the process of evolving away from the main sequence of stars like the Sun. It has about 162% of the Sun's mass and is radiating more than 11 times the luminosity of the Sun. This energy is being emitted from the outer envelope of the star at an effective temperature of 6,464 K. This causes the star to take on the yellow-white hue common to F-type stars.
X-ray emission has been detected from this star, which has an estimated X-ray luminosity of . It has the spectroscopic signature of a rapidly rotating star, with a projected rotational velocity of about 66 km s−1.
References
External links
F-type subgiants
Gemini (constellation)
Geminorum, Xi
Alzirr
0242
Geminorum, 31
032362
2484
048737
Durchmusterung objects | Xi Geminorum | [
"Astronomy"
] | 597 | [
"Gemini (constellation)",
"Constellations"
] |
3,116,378 | https://en.wikipedia.org/wiki/Tau2%20Eridani | {{DISPLAYTITLE:Tau2 Eridani}}
Tau2 Eridani (τ2 Eridani, abbreviated Tau2 Eri, τ2 Eri), formally named Angetenar , is a star in the constellation of Eridanus. It is visible to the naked eye with an apparent visual magnitude of 4.78. The distance to this star, as determined via the parallax method, is around 187 light-years.
Nomenclature
τ2 Eridani (Latinised to Tau2 Eridani) is the system's Bayer designation. It is one of a series of stars that share the Bayer designation Tau Eridani.
It bore the traditional name Angetenar, derived from the Arabic Al Ḥināyat an-Nahr, 'the Bend in the River', near which it lies. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name Angetenar for this star on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning Celestial Meadows, refers to an asterism consisting of Tau2 Eridani, Gamma Eridani, Pi Eridani, Delta Eridani, Epsilon Eridani, Zeta Eridani, Eta Eridani, Pi Ceti, Tau1 Eridani, Tau3 Eridani, Tau4 Eridani, Tau5 Eridani, Tau6 Eridani, Tau7 Eridani, Tau8 Eridani and Tau9 Eridani. Consequently, the Chinese name for Tau2 Eridani itself is (, .)
Properties
Tau2 Eridani is an evolved K-type giant star with a stellar classification of K0 III. It is a red clump giant on the horizontal branch of the Hertzsprung–Russell diagram, indicating that is it now generating energy through the thermonuclear fusion of helium at its core.
Around 720 million years old, Tau2 Eridani has 2.4 times the mass of the Sun and has expanded to over 8 times the solar radius. It shines with nearly 44 times the Sun's luminosity from an outer atmosphere that has an effective temperature of 5,049 K.
It is a member of the Galactic thin disk population.
References
K-type giants
Horizontal-branch stars
Eridanus (constellation)
Angetenar
Eridani, Tau2
Durchmusterung objects
Eridani, 02
017824
013288
0850 | Tau2 Eridani | [
"Astronomy"
] | 542 | [
"Eridanus (constellation)",
"Constellations"
] |
3,116,389 | https://en.wikipedia.org/wiki/Eta%20Eridani | Eta Eridani (η Eridani, abbreviated Eta Eri, η Eri), officially named Azha (with a silent 'h', possibly ), is a giant star in the constellation of Eridanus. Based on parallax measurements taken during the Hipparcos mission, it is approximately 137 light-years from the Sun.
Nomenclature
η Eridani (Latinised to Eta Eridani) is the star's Bayer designation.
It bore the traditional name Azha, from the old Arab asterism نَعَام أُدْحِيّ udḥiyy al-naʽām "the ostrich nest" (or "hatching place"), which included Eta Eridani. The first word, ادحى udḥiyy, was miscopied as ازحى (readable as azḥā) in medieval manuscripts.
In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name Azha for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning Celestial Meadows, refers to an asterism consisting of Eta Eridani, Gamma Eridani, Pi Eridani, Delta Eridani, Epsilon Eridani, Zeta Eridani, Pi Ceti, Tau1 Eridani, Tau2 Eridani, Tau3 Eridani, Tau4 Eridani, Tau5 Eridani, Tau6 Eridani, Tau7 Eridani, Tau8 Eridani and Tau9 Eridani. Consequently, the Chinese name for Eta Eridani itself is (, ).
Properties
η Eridani belongs to spectral class K3 and has a giant luminosity class. It is an evolved star that has expanded to tens times the size of the sun and nearly sixty times its luminosity. It is red clump giant, a star slightly more massive than the sun which is currently fusing helium in its core. This is a mild barium star, sometimes referred to a "semi-barium" star. Although most barium stars are in binary systems, η Eridani has no known companion.
η Eridani is a high proper motion star, a relatively close star that is moving across the sky at a high rate compared to most stars. It is suspected to be a variable star with a range from magnitude 3.81 to 3.90.
References
K-type giants
Horizontal-branch stars
Barium stars
Suspected variables
Eridanus (constellation)
Eridani, Eta
Azha
Durchmusterung objects
Eridani, 03
018322
013701
0874 | Eta Eridani | [
"Astronomy"
] | 575 | [
"Eridanus (constellation)",
"Constellations"
] |
3,116,402 | https://en.wikipedia.org/wiki/Xi%20Puppis | Xi Puppis (ξ Puppis, abbreviated Xi Pup, ξ Pup) is a multiple star system in the southern constellation of Puppis. With an apparent visual magnitude of 3.35, it is one of the brighter members of this constellation. Based on parallax measurements made during the Hipparcos mission, it is located approximately from the Sun, with a 7.5% margin of error.
The system consists of a spectroscopic binary, designated Xi Puppis A, together with a third companion star, Xi Puppis B. A's two components are themselves designated Xi Puppis Aa (formally named Azmidi ) and Ab.
Nomenclature
ξ Puppis (Latinised to Xi Puppis) is the system's Bayer designation. The designations of the two constituents as Xi Puppis A and B, and those of A's components - Xi Puppis Aa and Ab - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
The system was sometimes known as Asmidiske (Azmidiske), a misspelling and misplacement of Aspidiske (from the Greek for 'little shield), the traditional name of Iota Carinae. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name Azmidi for the component Xi Puppis Aa on 1 June 2018 and it is now so included in the List of IAU-approved Star Names.
Properties
Because of the distance of this system from the Earth, its visual magnitude is reduced by 0.73 as a result of extinction from the intervening gas and dust.
Xi Puppis A presents as a yellow supergiant of spectral class G6 with a luminosity 8,300 times that of the Sun.
The 13th-magnitude companion, Xi Puppis B, is about 5 arcseconds distant and is a Sun-like star that orbits at least 2000 AU away with an orbital period of at least 26,000 years.
References
External links
Asmidiske
Puppis, Xi
Puppis, 07
Double stars
063700
038170
Puppis
G-type supergiants
Azmidi
3045
Durchmusterung objects | Xi Puppis | [
"Astronomy"
] | 496 | [
"Puppis",
"Constellations"
] |
3,116,420 | https://en.wikipedia.org/wiki/Epsilon%20Delphini | Epsilon Delphini (ε Delphini, abbreviated Eps Del, ε Del), officially named Aldulfin , is a solitary, blue-white hued star in the northern constellation of Delphinus. It is visible to the naked eye with an apparent visual magnitude of 4.03. Based upon an annual parallax shift of 9.87 mas as seen from the Earth, the system is located about 330 light-years from the Sun. At Epsilon Delphini's distance, the visual magnitude is diminished by an extinction factor of 0.11 due to interstellar dust. The star is moving closer to the Sun with a radial velocity of −19 km/s.
This is a B-type giant star with a stellar classification of B6 III. It has 4.6 times the Sun's radius and is radiating 676 times the solar luminosity from its photosphere at an effective temperature of 13,614 K. The star may be slightly variable, occasionally brightening to magnitude 3.95. It is spinning with a projected rotational velocity of 52 km/s.
Proper names
ε Delphini (Latinised to Epsilon Delphini) is the star's Bayer designation.
The star bore the traditional Arabic name ðanab ad-dulfīn or Dzaneb al Delphin, which appeared in the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket and which was translated into Latin as Cauda Delphini, meaning 'the dolphin's tail'. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name Aldulfin for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning Rotten Gourd, refers to an asterism consisting of Epsilon Delphini, Eta Delphini, Theta Delphini, Iota Delphini and Kappa Delphini. Consequently, the Chinese name for Epsilon Delphini itself is (, .). From this Chinese name, the name Pae Chaou was formed.
References
B-type giants
Suspected variables
Delphinus
Delphini, Epsilon
Aldulfin
Durchmusterung objects
Delphini, 02
195810
101421
7852 | Epsilon Delphini | [
"Astronomy"
] | 494 | [
"Delphinus",
"Constellations"
] |
3,116,430 | https://en.wikipedia.org/wiki/Iota%20Ceti | Iota Ceti (ι Cet, ι Ceti) is the Bayer designation for a star system in the equatorial constellation of Cetus. It has the traditional name Deneb Kaitos Shemali. The name was from the Arabic word ذنب قيطس الشمالي - dhanab qayṭas al-shamālī, meaning the northern tail of the sea monster. it is visible to the naked eye with an apparent visual magnitude of 3.562. Based upon an annual parallax shift of 11.7 mas, it lies around 280 light years from the Sun.
In Chinese, (), meaning Square Celestial Granary, refers to an asterism consisting of ι Ceti, η Ceti, θ Ceti, ζ Ceti, τ Ceti and 57 Ceti. Consequently, the Chinese name for ι Ceti itself is (, .)
This is an MK-standard star with a stellar classification of K1.5 III, indicating that it is an evolved K-type giant star. However, Houk and Swift (1999) list a classification of K1 II, which would indicate this is a bright giant. It is a suspected variable with a visual amplitude of around 0.05 magnitude. The star has about 3.7 times the mass of the Sun, 30 times the Sun's radius, and radiates 380 times the solar luminosity from its outer atmosphere at an effective temperature of 4,645 K.
Iota Ceti forms a wide astrometric pair with a common proper motion companion, a magnitude 10.40 star at an angular separation of 106.4 arcseconds along a position angle of 191° (as of 2014). This companion may be a K-type star.
References
K-type giants
Cetus
Ceti, Iota
Deneb Kaitos Shemali
Ceti, 08
BD-09 48
001562
001522
0074 | Iota Ceti | [
"Astronomy"
] | 402 | [
"Cetus",
"Constellations"
] |
3,116,438 | https://en.wikipedia.org/wiki/Eta%20Ceti | Eta Ceti (η Cet, η Ceti) is a star in the equatorial constellation of Cetus. It has the traditional name Deneb Algenubi or Algenudi. The apparent visual magnitude of this star is +3.4, making it the fourth-brightest star in this otherwise relatively faint constellation. The distance to this star can be measured directly using the parallax technique, yielding a value of .
This is a giant star that has been chosen a standard for the stellar classification of K2−IIIb. It has exhausted the hydrogen at its core and evolved away from the main sequence of stars like the Sun. (The classification is sometimes listed as K1.5 IIICN1Fe0.5, indicating a strong CN star with higher-than-normal abundance of cyanogen and iron relative to other stars of its class.) It is a red clump star that is generating energy through the nuclear fusion of helium at its core.
Eta Ceti has 1.7 times more mass than the Sun and its surface has expanded to 13 times the Sun's radius. It is radiating 74 times as much luminosity as the Sun from its photosphere at an effective temperature of 4,356 K. This heat gives the star the orange-hued glow of a K-type star.
In culture
The name Deneb Algenubi was from Arabic ذنب القيطس الجنوبي – al-dhanab al-qayṭas al-janūbī, meaning the southern tail of the sea monster. In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Aoul al Naamat (أول النعامات – awwil al naʽāmāt), which was translated into Latin as Prima Struthionum, meaning the first ostrich. This star, along with θ Cet (Thanih al Naamat), τ Cet (Thalath Al Naamat), ζ Cet (Baten Kaitos) and υ Cet, were Al Naʽāmāt (النعامات), the Hen Ostriches.
In Chinese, (), meaning Square Celestial Granary, refers to an asterism consisting of η Ceti, ι Ceti, θ Ceti, ζ Ceti, τ Ceti and 57 Ceti. Consequently, the Chinese name for η Ceti itself is (, ).
Planetary system
In 2014, two exoplanets around the star were discovered using the radial velocity method. Planets discovered by radial velocity have poorly known masses because if the orbit of the planets were inclined away from the line of sight, a much larger mass would have to compensate for the angle.
Eta Ceti b has a minimum mass of and an orbital period of 403.5 days (about 1.1 years), while Eta Ceti c has a minimum mass of and an orbital period of 751.9 days (2.06 years). Assuming the orbits of the two are coplanar, then the two planets must be locked in a 2:1 orbital resonance, otherwise the system would become dynamically unstable. Although the inclinations from the line of sight are unknown, the value is constrained to be 70° or less: if any higher, the higher masses would render the system dynamically unstable, with no stable solutions.
References
K-type giants
CN stars
Cetus
Ceti, Eta
BD–10 240
Ceti, 31
005364
0334
006805
Aoul al Naamat
J01083539-1010560
Planetary systems with two confirmed planets | Eta Ceti | [
"Astronomy"
] | 763 | [
"Cetus",
"Constellations"
] |
3,116,453 | https://en.wikipedia.org/wiki/Lambda%20Draconis | Lambda Draconis (λ Draconis, abbreviated Lam Dra, λ Dra), also named Giausar ( ), is a solitary, orange-red star in the northern circumpolar constellation of Draco. It is visible to the naked eye with an apparent visual magnitude of +3.85. Based upon an annual parallax shift of 9.79 mas as seen from the Earth, the star is located around 333 light years from the Sun.
This is an evolved red giant star on the asymptotic giant branch with a stellar classification of M0III-IIIa Ca1. It is a suspected slow irregular variable with a periodicity of roughly 1,100 days. It has an estimated 1.53 times the mass of the Sun and a measured radius of 70 times the radius of the Sun. It is radiating 884 times the solar luminosity from its photosphere at an effective temperature of 3,761 K.
Nomenclature
λ Draconis (Latinised to Lambda Draconis) is the star's Bayer designation.
It bore the traditional name Giausar (also written as Gianfar, Giansar and Giauzar) and Juza. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name Giausar for this star on February 1, 2017, and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning Right Wall of Purple Forbidden Enclosure, refers to an asterism consisting of Lambda Draconis, Alpha Draconis, Kappa Draconis, 24 Ursae Majoris, 43 Camelopardalis, Alpha Camelopardalis and BK Camelopardalis. Consequently, the Chinese name for Lambda Draconis itself is (, .), representing (), meaning First Minister. 上輔 (Shǎngfǔ) was westernized into Sang Poo or Shaou Poo by R.H. Allen.
Namesakes
USS Giansar (AK-111) was a United States Navy Crater class cargo ship named after the star.
References
M-type giants
Asymptotic-giant-branch stars
Semiregular variable stars
Suspected variables
Draco (constellation)
Draconis, Lambda
Durchmusterung objects
Draconis, 01
100029
056211
4434
Giausar | Lambda Draconis | [
"Astronomy"
] | 505 | [
"Constellations",
"Draco (constellation)"
] |
3,116,461 | https://en.wikipedia.org/wiki/Sigma%20Puppis | Sigma Puppis, Latinized from σ Puppis, is a binary star system in the southern constellation Puppis. It has an apparent visual magnitude of 3.25, which is bright enough to be visible to the naked eye at night from the Southern Hemisphere. Through a telescope, it appears as a bright, orange-hued star with a nearby white companion. Parallax measurements indicate this star is located at a distance of about from Earth.
This is a spectroscopic binary system, consisting of an orbiting pair of stars that have not been individually resolved with a telescope. Their orbital period is 257.8 days and the eccentricity is 0.17. The pair form an eclipsing binary of the Beta Lyrae type and a period of 130.5 days, or one half of their orbital period. The eclipse of the primary component causes a decline of 0.04 of a magnitude, while the secondary eclipse reduces the magnitude by 0.03.
The combined stellar classification is K5 III, which matches the spectrum of a giant star. The primary is 44 times larger than the Sun and 340 times more luminous. Its surface has an effective temperature of , giving it the orange hue of a K-type star. It shows the behavior of a slow irregular variable.
In addition to its binary components, Sigma Puppis has a more distant companion that has a matching proper motion, suggesting that it may be gravitationally bound to the binary. This magnitude 8.5 star is at an angular separation of 22.4 arcseconds with a position angle of 74° from Sigma Puppis, which is equivalent to a projected separation of . In 1970, American astronomer Olin J. Eggen suggested that Sigma Puppis belonged to a moving group of stars that share a similar motion through space, and thereby a common origin. It served as the eponym for this, the σ Puppis group. The existence of this group was later brought into question.
References
K-type giants
Beta Lyrae variables
Slow irregular variables
Spectroscopic binaries
Puppis
Puppis, Sigma
Durchmusterung objects
059717
036377
2878 | Sigma Puppis | [
"Astronomy"
] | 437 | [
"Puppis",
"Constellations"
] |
3,116,474 | https://en.wikipedia.org/wiki/Zeta%20Pegasi | Zeta Pegasi or ζ Pegasi, formally named Homam (), is a single star in the northern constellation of Pegasus. With an apparent visual magnitude of +3.4, this star is bright enough to be seen with the naked eye and is one of the brighter members of Pegasus. Parallax measurements place it at a distance of around from the Sun.
Nomenclature
ζ Pegasi (Latinised to Zeta Pegasi) is the star's Bayer designation.
It bore the traditional name Homam, meaning "Man of High Spirit" or "Lucky Star of High Minded". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name Homam for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.
In Chinese, (), meaning Thunder and Lightning, refers to an asterism consisting ζ Pegasi, ξ Pegasi, σ Pegasi, 55 Pegasi, 66 Pegasi and 70 Pegasi. Consequently, the Chinese name for ζ Pegasi itself is (), "the First Star of Thunder and Lightning".
Properties
This star has a stellar classification of B8 V, which identifies it as a large B-type main sequence star that is generating energy through the nuclear fusion of hydrogen at its core. The radius of this star is about four times that of the Sun. In 2007, John H. Goebel showed that Zeta Pegasi is a variable star, using data obtained from Gravity Probe B. It is a slowly pulsating B star that varies slightly in luminosity with a period of hours, completing 1.04566 cycles per day. Zeta Pegasi is about 120 million years old and is rotating rapidly with a projected rotational velocity in the range of . The effective temperature of its outer envelope is around , giving it the characteristic blue-white glow of a B-type star.
Zeta Pegasi has been examined for infrared excess that may indicate the presence of circumstellar matter, but none was found. This star does have two optical companions. The first is a magnitude 11.6 star at an angular separation of along a position angle of 139°, as of 1997. The second is an 11th magnitude star at a separation of with a position angle of 5°. Zeta Pegasi is not known to be a member of a stellar association.
References
B-type main-sequence stars
Slowly pulsating B-type stars
Pegasus (constellation)
Pegasi, Zeta
Durchmusterung objects
Pegasi, 42
214923
112029
8634
Homam | Zeta Pegasi | [
"Astronomy"
] | 548 | [
"Pegasus (constellation)",
"Constellations"
] |
3,116,487 | https://en.wikipedia.org/wiki/Gamma%20Ceti | Gamma Ceti (γ Ceti, abbreviated Gamma Cet, γ Cet) is a triple star system in the equatorial constellation of Cetus. It has a combined apparent visual magnitude of 3.47. Based upon parallax measurements, this star is located at a distance of about 80 light-years (24.4 parsecs) from the Sun.
The three components are designated Gamma Ceti A (officially named Kaffaljidhma , the traditional name for the entire system), B and C.
Nomenclature
γ Ceti (Latinised to Gamma Ceti) is the system's Bayer designation. The designations of the three components as Gamma Ceti A, B and C derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU). The close pair AB is also designated HIP 12706, HD 16970, and HR 804. The system of A, B, and C is collectively designated GJ 106.1 in the Gliese Catalogue of Nearby Stars.
Gamma Ceti bore the traditional names of or , derived from ('the cut-short hand'). According to a 1971 NASA memorandum, was originally the title for five stars: Gamma Ceti as , Xi1 Ceti as , Xi2 Ceti as , Delta Ceti as and Mu Ceti as (excluding Alpha Ceti and Lambda Ceti). The IAU Working Group on Star Names (WGSN) approved the name Kaffaljidhma for the component Gamma Ceti A on February 1, 2017.
In Chinese astronomy, , meaning 'Circular Celestial Granary', refers to an asterism consisting of Gamma Ceti, Alpha Ceti, Kappa1 Ceti, Lambda Ceti, Mu Ceti, Xi1 Ceti, Xi2 Ceti, Nu Ceti, Delta Ceti, 75 Ceti, 70 Ceti, 63 Ceti and 66 Ceti. Consequently, the Chinese name for Gamma Ceti itself is ('the Eighth Star of Circular Celestial Granary').
Triple system
Gamma Ceti appears to be a triple star system. The inner pair (A and B) have an angular separation of 2.6 arcseconds. The primary component of this pair (A) is an A-type main sequence star with a stellar classification of A3 V and a visual magnitude of 3.6. The fainter secondary component (B) is an F-type main sequence star that has a classification of F3 V and a magnitude of 6.6. The contrasting colors of these two stars makes them a popular target of amateur astronomers. The two can be resolved with a small, aperture telescope under ideal seeing conditions, although at times they can be a challenge to resolve even with a much larger scope.
At a wide separation of 840 arcseconds is component C, a dim, magnitude 10.2 K-type star with the designation . It shares a common proper motion with A and is at a very similar distance, but is separated from the close pair by over . It has a spectral classification of K5V. There are several other stars brighter and closer to Gamma Ceti than – , HD 16985, and – but they are all more distant background stars.
Properties
The measured angular diameter of the primary star is . At the estimated distance of this system, this yields a physical size of about 1.9 times the radius of the Sun. The secondary component of this system is an X-ray source with a luminosity of . Gamma Ceti is about 300 million years old, and it appears to be a member of the stream of stars loosely associated with the Ursa Major Moving Group. The primary has been examined for an excess of infrared emission that would suggest the presence of circumstellar matter, but none was found.
References
External links
Information about Kaffaljidhma on STARS
Gamma Ceti on AAS WorldWide Telescope
Cetus
Ceti, Gamma
Kaffaljidhma
Ceti, 86
A-type main-sequence stars
F-type main-sequence stars
K-type main-sequence stars
012706
016970
0804
Durchmusterung objects | Gamma Ceti | [
"Astronomy"
] | 867 | [
"Cetus",
"Constellations"
] |
3,116,506 | https://en.wikipedia.org/wiki/Omega%20Herculis | Omega Herculis (ω Herculis, abbreviated Ome Her, ω Her) is a binary star system in the northern constellation of Hercules. Based upon an annual parallax shift of 13.04 mas as seen from Earth, it is located around 250 light-years from the Sun. It is faintly visible to the naked eye, having a combined apparent visual magnitude of 4.58. The system is a candidate for membership in the Ursa Major Moving Group, although this remains uncertain.
The two components are designated Omega Herculis A (officially named Cujam , the traditional name of the system) and B.
Nomenclature
ω Herculis (Latinised to Omega Herculis) is the system's Bayer designation. It previously bore the Flamsteed designation of 51 Serpentis before being added to Hercules. The designations of the two components as Omega Herculis A and B derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
The system bore the traditional name Cujam (also written as Cajam and Kajam), meaning ("club"). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name Cujam for the component Omega Herculis A on February 1, 2017 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning Dipper for Liquid, refers to an asterism consisting of Omega Herculis, 49 Serpentis, 13 Herculis, 29 Herculis and 33 Herculis. Consequently, the Chinese name for Omega Herculis itself is (, ).
Properties
The primary, Omega Herculis A, is a chemically peculiar Ap star with a stellar classification of A2 Vp CrSr. The spectrum displays abnormally strong absorption lines of chromium and strontium, and weak lines of calcium and magnesium. An A-type star, it has an estimated 2.14 times the mass of the Sun and 3.30 times the Sun's radius. The star is around 149 million years old and is radiating 70 times the solar luminosity from its photosphere at an effective temperature of 10,052 K.
This component is an Alpha2 Canum Venaticorum variable with a brightness amplitude of 0.4 magnitude and a 2.951 day phase that presumably matches the rotation period. The pattern of variation shows that there are regions of the star's surface where the concentrations of elements differ. The star also displays short period variations on the order of 2.5 hours. It has a mean effective magnetic field value of .
The secondary, Omega Herculis B, is a magnitude 11.5 companion star. As of 2010, it was located at an angular separation of 0.80 arc seconds along a position angle of 294°.
References
A-type main-sequence stars
Ap stars
Binary stars
Ursa Major moving group
Hercules (constellation)
Herculis, Omega
Cujam
Durchmusterung objects
Herculis, 024
148112
080463
6117 | Omega Herculis | [
"Astronomy"
] | 683 | [
"Hercules (constellation)",
"Constellations"
] |
3,116,524 | https://en.wikipedia.org/wiki/Alpha%20Equulei | Alpha Equulei (α Equulei, abbreviated Alpha Equ, α Equ), officially named Kitalpha , is a star in the constellation of Equuleus. It is a high proper-motion star only 190 light-years away.
Nomenclature
α Equulei (Latinised to Alpha Equulei) is the star's Bayer designation.
It bore the traditional name Kitalpha (rarely Kitel Phard or Kitalphar), a contraction of the Arabic name قطعة الفرس qiṭ‘a(t) al-faras—"a piece of the horse". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name Kitalpha for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.
In Chinese, (), meaning Emptiness, is an asterism consisting of Alpha Equulei and Beta Aquarii. Consequently, the Chinese name for Alpha Equulei itself is (, ).
Properties
The overall appearance of α Equulei is a G-type giant with an apparent magnitude of +3.92, but it is a spectroscopic binary consisting of two individual stars.
The primary star is a G7 giant about fifty times more luminous than the Sun. It has an effective temperature of and a radius of 9.2 times greater than the Sun.
The secondary is an A-type dwarf about 26 times as luminous as the sun. It has an effective temperature of 8,150 K and a radius 2.6 times greater than the sun. It is a chemically peculiar Am star.
The two stars revolve in a circular orbit every 98.8 days. Their respective orbital velocities allow their masses to be calculated at and , respectively.
References
Equulei, Alpha
Equuleus
G-type giants
A-type main-sequence stars
Spectroscopic binaries
Kitalpha
104987
Equulei, 08
8131
202447
BD+04 4635 | Alpha Equulei | [
"Astronomy"
] | 451 | [
"Equuleus",
"Constellations"
] |
3,116,538 | https://en.wikipedia.org/wiki/Beta%20Herculis | Beta Herculis (β Herculis, abbreviated Beta Her, β Her), formally named Kornephoros , or Rutilicus, is a binary star and the brightest star in the northern constellation of Hercules at a base apparent visual magnitude of 2.81. This is a suspected variable star with an apparent magnitude that may rise as high as 2.76. Based upon parallax measurements, it is located at a distance of from the Sun.
Although Beta Herculis appears to the naked eye to be a single star, in July 1899 the American astronomer W. W. Campbell discovered from spectroscopic measurements that its radial velocity varies, and concluded that it has a companion.
Properties
At Palomar Observatory, Antoine Labeyrie and others used speckle interferometry with the Hale Telescope to resolve the system in 1977. The Hipparcos satellite observed the orbital motion of the primary relative to other stars, and an orbit was computed in 2005 using spectroscopic data together with these measurements. The period of the system is around 410 days. They have a high orbital eccentricity of 0.55 and the orbital plane is inclined 53.8° to the line of sight from the Earth.
The primary star has a stellar classification of G7 IIIa, indicating that it is a giant star that has exhausted the hydrogen at its core and evolved away from the main sequence. It is most likely fusing helium into carbon and oxygen in its core, qualifying it as a horizontal branch or red clump star. With a mass nearly three times the mass of the Sun, it was most likely a B-type main-sequence star similar to Beta Librae prior to core hydrogen exhaustion. It is comparable to the main component of Capella, albeit warmer and brighter. Being 420 million years old, it has expanded to 16 times the Sun's radius and is radiating 150 times its luminosity. The effective temperature of the star's outer envelope is about 5,100 K, which gives it the yellow hue of a G-type star. The secondary star has a mass only 90% that of the Sun.
With insufficient mass to explode as a supernova, Beta Herculis will most likely become a white dwarf similar to Sirius B.
Nomenclature
β Herculis (Latinised to Beta Herculis) is the star's Bayer designation.
It bore the traditional names Kornephoros, a Greek word meaning "club bearer", and Rutilicus, a corruption of the Latin word titillicus, meaning "armpit". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name Kornephoros for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.
It was a member of the indigenous Arabic asterism al-Nasaq al-Shāmī, "the Northern Line" of al-Nasaqān "the Two Lines", along with Gamma Herculis, Gamma Serpentis and Beta Serpentis. Though, according to a 1971 NASA catalog, al-Nasaq al-Sha'āmī or Nasak Shamiya was the title for three other stars: Beta Serpentis as Nasak Shamiya I, Gamma Serpentis as Nasak Shamiya II and Gamma Herculis as Nasak Shamiya III.
In Chinese, (), meaning Right Wall of Heavenly Market Enclosure, refers to an asterism which represents eleven old states in China and which is marking the right borderline of the enclosure, consisting of Beta Herculis, Gamma Herculis, Kappa Herculis, Gamma Serpentis, Beta Serpentis, Delta Serpentis, Alpha Serpentis, Epsilon Serpentis, Delta Ophiuchi, Epsilon Ophiuchi and Zeta Ophiuchi. Consequently, the Chinese name for Beta Herculis itself is (, ), represent Hézhōng (河中), possibly Hezhong Municipality or Hezhong Circuit (see : Wang Chongrong, formally the Prince of Langye 瑯琊王, was a warlord of the late Chinese Tang dynasty who controlled Hezhong Circuit, headquartered in modern Yuncheng, Shanxi). Hézhōng (河中) was westernized into Ho Chung by R.H. Allen, which means "in the river".
Namesake
USS Rutilicus (AK-113) was a United States Navy Crater class cargo ship named after the star.
References
Hercules (constellation)
G-type giants
Triple stars
Binary stars
Herculis, Beta
Herculis, 027
148856
080816
Kornephoros
BD+21 2934
6148 | Beta Herculis | [
"Astronomy"
] | 967 | [
"Hercules (constellation)",
"Constellations"
] |
3,116,557 | https://en.wikipedia.org/wiki/Delta%20Cassiopeiae | Delta Cassiopeiae (δ Cassiopeiae, abbreviated Delta Cas, δ Cas) is an eclipsing binary star system in the northern circumpolar constellation of Cassiopeia. Based on parallax measurements taken during the Hipparcos mission, it is approximately from the Earth.
Delta Cassiopeiae is the primary or 'A' component of a multiple star system designated WDS J01258+6014. Delta Cassiopeiae's two components are therefore designated WDS J01258+6014 Aa and Ab. Aa is officially named Ruchbah , the traditional name for the system.
Nomenclature
δ Cassiopeiae (Latinised to Delta Cassiopeiae) is the star's Bayer designation. WDS J01258+6014A is its designation in the Washington Double Star Catalog.
It also bore the traditional names Ruchbah and Ksora; the former deriving from the Arabic word ركبة rukbah meaning "knee", and the latter appeared in a 1951 publication, Atlas Coeli (Skalnate Pleso Atlas of the Heavens) by Czech astronomer Antonín Bečvář. Professor Paul Kunitzch has been unable to find any clues as to the origin of the name. The star Alpha Sagittarii also bore the traditional name Ruchbah (as well as Rukbat). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name Ruchbah for the component WDS J01258+6014 Aa on 21 August 2016 and it is now so included in the List of IAU-approved Star Names (Alpha Sagittarii's primary was given the name Rukbat).
In Chinese, (), meaning Flying Corridor, refers to an asterism consisting of Delta Cassiopeiae, Iota Cassiopeiae, Epsilon Cassiopeiae, Theta Cassiopeiae, Nu Cassiopeiae and Omicron Cassiopeiae. Consequently, the Chinese name for Delta Cassiopeiae itself is (, ).
Properties
Delta Cassiopeiae is a possible eclipsing binary star system consisting of a pair of stars that orbit about each other over a period of 759 days. The combined apparent visual magnitude of the two stars is 2.68, making it readily observable with the naked eye. Eclipses have been reported with a period of 759 days, when the brightness drops by 0.07 magnitudes. Modern studies have shown no brightness variations greater than 0.01 magnitudes.
The primary member of the system (WDS J01258+6014 Aa) has a stellar classification of A5 IV, with the luminosity class of IV indicating that it has exhausted the hydrogen at its core and has begun to evolve through the subgiant phase into a giant star. It is calculated that it is 4% beyond the end of its main sequence lifetime, with an age of about 600 million years. It has expanded to about 3.9 times the Sun's radius.
An excess infrared emission has been observed at a wavelength of 60 μm, which suggests the presence of a circumstellar debris disk. This emission can be characterized by heat radiated from dust at a temperature of 85 K, which corresponds to an orbital radius of 88 Astronomical Units, or 88 times the distance of the Earth from the Sun. For comparison, the region of the remote Kuiper belt in the Solar System extends from 30–50 AU.
The Washington Double Star Catalog lists a 12th magnitude companion away. It is an unrelated background object.
References
Cassiopeia (constellation)
Cassiopeiae, Delta
Eclipsing binaries
A-type subgiants
Ruchbah
Cassiopeiae, 37
006686
0403
008538
Durchmusterung objects | Delta Cassiopeiae | [
"Astronomy"
] | 811 | [
"Cassiopeia (constellation)",
"Constellations"
] |
3,116,570 | https://en.wikipedia.org/wiki/La%20Superba | La Superba (Y CVn, Y Canum Venaticorum) is a strikingly red giant star in the constellation Canes Venatici. It is faintly visible to the naked eye, and the red colour is very obvious in binoculars. It is a carbon star and semiregular variable.
Visibility
La Superba is a semiregular variable star, varying by about a magnitude over a roughly 160-day cycle, but with slower variation over a larger range. Periods of 194 and 186 days have been suggested, with a resonance between the periods.
Y CVn is one of the reddest stars known, and it is among the brightest of the giant red carbon stars. It is the brightest of known J-stars, which are a very rare category of carbon stars that contain large amounts of carbon-13 (carbon atoms with 7 neutrons instead of the usual 6). The 19th century astronomer Angelo Secchi, impressed with its beauty, gave the star its common name, which is now accepted by the International Astronomical Union.
Properties
Calculations with La Superba's luminosity and effective temperature give it a radius of about . If it were placed at the position of the Sun, the star's surface would extend beyond Earth's orbit.
La Superba's temperature is believed to be about , making it one of the coolest true stars known. When infrared radiation is included, Y CVn has a bolometric luminosity several thousand times that of the Sun. The mass of this type of star is difficult to determine; it would initially have been around and somewhat less now due to mass loss. An estimate from Jim Kaler gives the star a luminosity between and radius between based on an assumed temperature of 3,000 K, and the author then classified it as a C7 or CN5 supergiant star although its mass is too low to be a true supergiant.
Observations in the 60 and 100 micron infrared bands by the IRAS satellite showed that Y CVn is surrounded by a dust shell 0.9 parsecs in diameter.
This is one of the most prominent circumstellar dust shells detected in the IRAS all-sky survey.
Evolution
After stars up to a few times the mass of the sun have finished fusing hydrogen to helium in their core, they start to burn hydrogen in a shell outside a degenerate helium core, and expand dramatically into the red giant state. Once the core reaches a high enough temperature, it ignites violently in the helium flash, which begins helium core burning on the horizontal branch. Once even the core helium is exhausted, a degenerate carbon-oxygen core remains. Fusion continues in both hydrogen and helium shells at different depths in the star, and the star increases luminosity on the asymptotic giant branch (AGB). La Superba is currently an AGB star.
In the AGB stars, fusion products are moved outwards from the core by strong deep convection known as a dredge-up, thus creating a carbon abundance in the outer atmosphere where carbon monoxide and other compounds are formed. These molecules tend to absorb radiation at shorter wavelengths, resulting in a spectrum with even less blue and violet compared to ordinary red giants, giving the star its distinguished red color.
La Superba is most likely in the final stages of fusing its remaining secondary fuel (helium) into carbon and shedding its mass at the rate of about a million times that of the Sun's solar wind. It is also surrounded by a 2.5 light year-wide shell of previously ejected material, implying that at one point it must have been losing mass as much as 50 times faster than it is now. La Superba thus appears almost ready to eject its outer layers to form a planetary nebula, leaving behind its core in the form of a white dwarf.
Notes
References
External links
https://web.archive.org/web/20051025230148/http://www.nckas.org/carbonstars/
http://www.backyard-astro.com/deepsky/top100/11.html
http://jumk.de/astronomie/big-stars/la-superba.shtml
Semiregular variable stars
Canes Venatici
Carbon stars
Stars with proper names
Canum Venaticorum, Y
110914
4846
062223
Durchmusterung objects
Asymptotic-giant-branch stars | La Superba | [
"Astronomy"
] | 922 | [
"Canes Venatici",
"Constellations"
] |
3,116,592 | https://en.wikipedia.org/wiki/Lambda%20Herculis | Lambda Herculis (λ Herculis. abbreviated Lambda Her, λ Her), formally named Maasym , is a star in the constellation of Hercules. From parallax measurements taken during the Gaia mission, it is approximately 393 light-years from the Sun.
Nomenclature
λ Herculis (Latinised to Lambda Herculis) is the star's Bayer designation.
It bore the traditional name Maasym, from the Arabic مِعْصَم miʽṣam "wrist". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name Maasym for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning Left Wall of Heavenly Market Enclosure, refers to an asterism which represents eleven old states in China and which is marking the left borderline of the enclosure, consisting of Lambda Herculis, Delta Herculis, Mu Herculis, Omicron Herculis, 112 Herculis, Zeta Aquilae, Theta1 Serpentis, Eta Serpentis, Nu Ophiuchi, Xi Serpentis and Eta Ophiuchi. Consequently, the Chinese name for Lambda Herculis itself is (, ), and represents the state Zhao (or Chaou (趙)), together with 26 Capricorni and 27 Capricorni ("m Capricorni" in R.H.Allen version) in Twelve States (asterism).
Description
Lambda Herculis has an apparent magnitude of 4.4. It has been listed as a standard star for the spectral class spectral class K3.5III, indicating that it is a red giant with a temperature of about . Visually it has an absolute magnitude of −0.86, meaning it is nearly 200 times brighter than the sun, but its bolometric luminosity across all wavelengths is over . It is unclear whether the star is on the red giant branch and fusing hydrogen in a shell or on the horizontal branch (red clump) and fusing helium in its core. As a horizontal-branch star it would be about seven billion years old, but as a red-giant-branch star it would only be about four billion years old.
In 1783, English-German astronomer William Herschel described the solar apex, the point in sky towards which the Solar System is moving; using data from double stars, he identified this position as close to Lambda Herculis. Today it is known the solar apex is not so close to this star, however it is only 10° away from the position currently accepted (in Hercules, southwest of Vega).
References
Hercules (constellation)
Herculis, Lambda
K-type giants
Maasym
Herculis, 076
085693
6526
158899
Durchmusterung objects | Lambda Herculis | [
"Astronomy"
] | 605 | [
"Hercules (constellation)",
"Constellations"
] |
3,116,599 | https://en.wikipedia.org/wiki/Theta%20Cassiopeiae | Theta Cassiopeiae or θ Cassiopeiae is a solitary star in the northern constellation of Cassiopeia. It shares the traditional name Marfak with μ Cassiopeiae, positioned less than half a degree to the WSW, which is derived from the Arabic term Al Marfik or Al Mirfaq (المرفق), meaning "the elbow". At an apparent visual magnitude of 4.3, Theta Cassiopeiae is visible to the naked eye. Based upon an annual parallax shift of 24.42 mas, it is located about 134 light years from the Sun. It has a total annual proper motion of 0.227 arcseconds per year, and is slowly drifting further away from the Sun with a radial velocity of 2.5 km/s.
In Chinese, (), meaning Flying Corridor, refers to an asterism consisting of θ Cassiopeiae, ι Cassiopeiae, ε Cassiopeiae, δ Cassiopeiae, ν Cassiopeiae and ο Cassiopeiae. Consequently, θ Cassiopeiae itself is known as (, .)
This is an A-type main sequence star with a stellar classification of A7 V. The measured angular diameter of this star is , which, at the estimated distance of this star, yields a physical size of about 2.6 times the radius of the Sun. It is about 650 million years in age and is spinning with a projected rotational velocity of 103 km/s. This is a candidate Vega-type system, which means it displays an infrared excess suggesting it has an orbiting debris disk. It is a suspected Delta Scuti variable.
The star appears to be a member of a leading tidal tail of the Hyades cluster.
References
External links
</ref>
A-type main-sequence stars
Cassiopeia (constellation)
Cassiopeiae, Theta
Durchmusterung objects
Cassiopeiae, 33
006961
005542
0343
Marfak | Theta Cassiopeiae | [
"Astronomy"
] | 418 | [
"Cassiopeia (constellation)",
"Constellations"
] |
3,116,612 | https://en.wikipedia.org/wiki/Lambda%20Ophiuchi | λ Ophiuchi, Latinized as Lambda Ophiuchi, is a triple star system in the equatorial constellation of Ophiuchus. It has the traditional name Marfik , which now applies exclusively to the primary component. The system is visible to the naked eye as a faint point of light with an apparent visual magnitude of 3.82. It is located approximately 173 light-years from the Sun, based on its parallax, but is drifting closer with a radial velocity of –16 km/s.
System
The inner pair form a binary star system with an orbital period of 192 years and an eccentricity of 0.611. Both components are A-type main-sequence stars, indicating that they are generating energy through core hydrogen fusion. The brighter member of this pair, designated component A, is the primary for the system with a visual magnitude of 4.18 and a stellar classification of A0V. The secondary, component B, is magnitude 5.22 and class A4V.
Component C is magnitude 11.0 and lies at an angular separation of from the inner pair. It has a common proper motion and is at approximately the same distance as the other two stars, although any orbit would last for hundreds of thousands of years. It has a mass 72% of the Sun's, a radius 58% of the Sun's, a temperature of about , and 7% of the Sun's luminosity. It has an estimated spectral type of K6.
Nomenclature
λ Ophiuchi is the system's Bayer designation. The designations of the three components as Lambda Ophiuchi A, B and C derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
It bore the traditional name Marfik (or Marsik), from the Arabic مرفق marfiq "elbow". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name Marfik for the component Lambda Ophiuchi A on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.
References
External links
Various star data
A-type main-sequence stars
Suspected variables
Binary stars
Triple stars
Ophiuchus
Ophiuchi, Lambda
Durchmusterung objects
Ophiuchi, 10
148857
080883
6149
Marfik | Lambda Ophiuchi | [
"Astronomy"
] | 528 | [
"Sky regions",
"Ophiuchus",
"Multiple stars",
"Constellations"
] |
3,116,639 | https://en.wikipedia.org/wiki/Sigma%20Hydrae | Sigma Hydrae (σ Hydrae, abbreviated Sigma Hya, σ Hya), also named Minchir , is a solitary star in the equatorial constellation of Hydra. It is visible to the naked eye with an apparent visual magnitude of 4.48. The estimated distance to this star from the Sun, based upon an annual parallax shift of 8.75 mas, is around 370 light-years. At that distance, the visual magnitude of the star is diminished by an interstellar extinction factor of 0.16, due to intervening dust.
Nomenclature
σ Hydrae (Latinised to Sigma Hydrae) is the system's Bayer designation.
It bore the traditional name Minchir, appearing as Minchir es-schudscha in Bode's large star atlas, Uranographia. The name which derived from the Arabic appelationمنخر الشجاع minkhar ash-shujāʽ "the nostril brave one" (the hydra) for this star. The name is erroneously spelt as Al Minliar al Shuja in the Yale Bright Star Catalogue. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name Minchir for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.
This star, along with Delta Hydrae (Lisan al Shudja), Epsilon Hydrae, Zeta Hydrae, Eta Hydrae and Rho Hydrae, were Ulug Beg's Min al Azʽal, "Belonging to the Uninhabited Spot". (According to a 1971 NASA memorandum, Min al Azʽal or Minazal were the title for five stars : Delta Hydrae as Minazal I, Eta Hydrae as Minazal II, Epsilon Hydrae as Minazal III, Rho Hydrae as Minazal IV and Zeta Hydrae as Minazal V.)
In Chinese, (), meaning Willow (asterism), refers to an asterism consisting of Sigma Hydrae, Delta Hydrae, Eta Hydrae, Rho Hydrae, Epsilon Hydrae, Zeta Hydrae, Omega Hydrae and Theta Hydrae. Consequently, Sigma Hydrae itself is known as (, ).
The people of Groote Eylandt, used the name Unwala ("The Crab") for the star cluster including this star, Delta Hydrae (Lisan al Shudja), Epsilon Hydrae, Zeta Hydrae, Eta Hydrae and Rho Hydrae.
Properties
This is an evolved K-type giant star with a stellar classification of K2 III. The measured angular diameter of this star, after correction for limb darkening, is . At its estimated distance, this yields a physical size of about 27.6 times the radius of the Sun. It has about three times the mass of the Sun and radiates 295 times the solar luminosity from its outer atmosphere at an effective temperature of 4,491 K. Sigma Hydrae is around 430 million years old.
References
K-type giants
Hydrae, Sigma
Hydra (constellation)
Minchir
Durchmusterung objects
Hydrae, 05
073471
042402
3418 | Sigma Hydrae | [
"Astronomy"
] | 671 | [
"Hydra (constellation)",
"Constellations"
] |
3,116,655 | https://en.wikipedia.org/wiki/Epsilon%20Corvi | Epsilon Corvi (ε Crv, ε Corvi) is a star in the southern constellation of Corvus. It has the traditional name Minkar , from Arabic منقار minqar meaning "beak [of the crow]" The apparent visual magnitude is +3.0 and it is located at a distance of from Earth.
In Chinese, (), meaning Chariot (asterism), refers to an asterism consisting of ε Corvi, γ Corvi, δ Corvi and β Corvi. Consequently, ε Corvi itself is known as (, .).
Epsilon Corvi is a red giant with a stellar classification of K2 III, having consumed the hydrogen at its core and evolved away from the main sequence. It has about three times the Sun's mass. The interferometry-measured angular diameter of this star is about 4.99 mas, which, at its estimated distance, equates to a physical radius of about 52 times the radius of the Sun. The effective temperature of the outer envelope is , giving it an orange hue that is characteristic of a K-type star. Around 4 times as massive as the Sun, it spent much of its life as a main sequence star of spectral type B5V.
References
Corvus (constellation)
Corvi, Epsilon
Minkar
Corvi, 02
059316
K-type giants
4630
105707
Durchmusterung objects | Epsilon Corvi | [
"Astronomy"
] | 307 | [
"Corvus (constellation)",
"Constellations"
] |
3,116,754 | https://en.wikipedia.org/wiki/Beta%20Corvi | Beta Corvi or β Corvi, officially named Kraz (), is the second-brightest star in the southern constellation of Corvus with an apparent visual magnitude of 2.647. Based on parallax measurements obtained during the Hipparcos mission, it is about distant from the Sun.
Nomenclature
β Corvi (Latinised to Beta Corvi) is the star's Bayer designation.
In a 1951 publication, Atlas Coeli (Skalnate Pleso Atlas of the Heavens) by Czech astronomer Antonín Bečvář, it bore the name Kraz, whose origin and meaning remain unknown.
In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name Kraz for this star on 1 June 2018 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning Chariot (asterism), refers to an asterism consisting of Beta, Gamma, Epsilon and Delta Corvi. Consequently, Beta Corvi itself is known as (, ).
Properties
Beta Corvi has about 3.3 times the Sun's mass and is roughly 300 million years old, which is old enough for a star of this mass to consume the hydrogen at its core and evolve away from the main sequence. The stellar classification is G5 II, with the luminosity class of 'II' indicating this is a bright giant. The effective temperature of the star's outer envelope is about 5,325 K, which produces a yellow hue common to G-type stars.
Currently, Beta Corvi has expanded to 15.8 times the Sun's size and is emitting about 175 times the luminosity of the Sun. The abundance of elements other than hydrogen or helium, what astronomers term metallicity, is 1.38 times that of the Sun.
This is a variable star that ranges in apparent visual magnitude from a low of 2.66 to a high of 2.60.
See also
List of stars in Corvus
Beta Leporis, another bright giant star with similar size and spectral type
Notes
References
G-type bright giants
Corvus (constellation)
Corvi, Beta
BD-22 3401
Corvi, 9
109379
061359
4786
Kraz | Beta Corvi | [
"Astronomy"
] | 490 | [
"Corvus (constellation)",
"Constellations"
] |
3,116,835 | https://en.wikipedia.org/wiki/Complete%20intersection | In mathematics, an algebraic variety V in projective space is a complete intersection if the ideal of V is generated by exactly codim V elements. That is, if V has dimension m and lies in projective space Pn, there should exist n − m homogeneous polynomials:
in the homogeneous coordinates Xj, which generate all other homogeneous polynomials that vanish on V.
Geometrically, each Fi defines a hypersurface; the intersection of these hypersurfaces should be V. The intersection of hypersurfaces will always have dimension at least m, assuming that the field of scalars is an algebraically closed field such as the complex numbers. The question is essentially, can we get the dimension down to m, with no extra points in the intersection? This condition is fairly hard to check as soon as the codimension . When then V is automatically a hypersurface and there is nothing to prove.
Examples
Easy examples of complete intersections are given by hypersurfaces which are defined by the vanishing locus of a single polynomial. For example,
gives an example of a quintic threefold. It can be difficult to find explicit examples of complete intersections of higher dimensional varieties using two or more explicit examples (bestiary), but, there is an explicit example of a 3-fold of type given by
Non-examples
Twisted cubic
One method for constructing local complete intersections is to take a projective complete intersection variety and embed it into a higher dimensional projective space. A classic example of this is the twisted cubic in : it is a smooth local complete intersection meaning in any chart it can be expressed as the vanishing locus of two polynomials, but globally it is expressed by the vanishing locus of more than two polynomials. We can construct it using the very ample line bundle over giving the embedding
by
Note that . If we let the embedding gives the following relations:
Hence the twisted cubic is the projective scheme
Union of varieties differing in dimension
Another convenient way to construct a non complete intersection, which can never be a local complete intersection, is by taking the union of two different varieties where their dimensions do not agree. For example, the union of a line and a plane intersecting at a point is a classic example of this phenomenon. It is given by the scheme
Multidegree
A complete intersection has a multidegree, written as the tuple (properly though a multiset) of the degrees of defining hypersurfaces. For example, taking quadrics in P3 again, (2,2) is the multidegree of the complete intersection of two of them, which when they are in general position is an elliptic curve. The Hodge numbers of complex smooth complete intersections were worked out by Kunihiko Kodaira.
General position
For more refined questions, the nature of the intersection has to be addressed more closely. The hypersurfaces may be required to satisfy a transversality condition (like their tangent spaces being in general position at intersection points). The intersection may be scheme-theoretic, in other words here the homogeneous ideal generated by the Fi(X0, ..., Xn) may be required to be the defining ideal of V, and not just have the correct radical. In commutative algebra, the complete intersection condition is translated into regular sequence terms, allowing the definition of local complete intersection, or after some localization an ideal has defining regular sequences.
Topology
Homology
Since complete intersections of dimension in are the intersection of hyperplane sections, we can use the Lefschetz hyperplane theorem to deduce that
for . In addition, it can be checked that the homology groups are always torsion-free using the universal coefficient theorem. This implies that the middle homology group is determined by the Euler characteristic of the space.
Euler characteristic
Hirzebruch gave a generating function computing the dimension of all complete intersections of multi-degree . It reads
Citation
References
External links
Complete intersections at the Manifold Atlas
Algebraic geometry
Commutative algebra | Complete intersection | [
"Mathematics"
] | 807 | [
"Fields of abstract algebra",
"Commutative algebra",
"Algebraic geometry"
] |
3,116,851 | https://en.wikipedia.org/wiki/Complete%20intersection%20ring | In commutative algebra, a complete intersection ring is a commutative ring similar to the coordinate rings of varieties that are complete intersections. Informally, they can be thought of roughly as the local rings that can be defined using the "minimum possible" number of relations.
For Noetherian local rings, there is the following chain of inclusions:
Definition
A local complete intersection ring is a Noetherian local ring whose completion is the quotient of a regular local ring by an ideal generated by a regular sequence. Taking the completion is a minor technical complication caused by the fact that not all local rings are quotients of regular ones. For rings that are quotients of regular local rings, which covers most local rings that occur in algebraic geometry, it is not necessary to take completions in the definition.
There is an alternative intrinsic definition that does not depend on embedding the ring in a regular local ring.
If R is a Noetherian local ring with maximal ideal m, then the dimension of m/m2 is called the embedding dimension emb dim (R) of R. Define a graded algebra H(R) as the homology of the Koszul complex with respect to a minimal system of generators of m/m2; up to isomorphism this only depends on R and not on the choice of the generators of m. The dimension of H1(R) is denoted by ε1 and is called the first deviation of R; it vanishes if and only if R is regular.
A Noetherian local ring is called a complete intersection ring if its
embedding dimension is the sum of the dimension and the first deviation:
emb dim(R) = dim(R) + ε1(R).
There is also a recursive characterization of local complete intersection rings that can be used as a definition, as follows. Suppose that R is a complete Noetherian local ring. If R has dimension greater than 0 and x is an element in the maximal ideal that is not a zero divisor then R is a complete intersection ring if and only if R/(x) is. (If the maximal ideal consists entirely of zero divisors then R is not a complete intersection ring.) If R has dimension 0, then showed that it is a complete intersection ring if and only if the Fitting ideal of its maximal ideal is non-zero.
Examples
Regular local rings
Regular local rings are complete intersection rings, but the converse is not true: the ring is a 0-dimensional complete intersection ring that is not regular.
Not a complete intersection
An example of a locally complete intersection ring which is not a complete intersection ring is given by which has length 3 since it is isomorphic as a vector space to .
Counterexample
Complete intersection local rings are Gorenstein rings, but the converse is not true: the ring is a 0-dimensional Gorenstein ring that is not a complete intersection ring. As a -vector space this ring is isomorphic to
, where , and
showing it is Gorenstein since the top-degree component is dimension and it satisfies the Poincare property. It is not a local complete intersection ring because the ideal is not -regular. For example, is a zero-divisor to in .
Citations
References
Commutative algebra | Complete intersection ring | [
"Mathematics"
] | 671 | [
"Fields of abstract algebra",
"Commutative algebra"
] |
3,117,016 | https://en.wikipedia.org/wiki/List%20of%20textbooks%20in%20thermodynamics%20and%20statistical%20mechanics | A list of notable textbooks in thermodynamics and statistical mechanics, arranged by category and date.
Only or mainly thermodynamics
Both thermodynamics and statistical mechanics
2e Kittel, Charles; and Kroemer, Herbert (1980) New York: W.H. Freeman
2e (1988) Chichester: Wiley , .
(1990) New York: Dover
Stephen G. Brush (1976) The Kind of Motion We Call Heat I-II North-Holland ISBN 0-444-87008-3
Statistical mechanics
. 2e (1936) Cambridge: University Press; (1980) Cambridge University Press.
; (1979) New York: Dover
Vol. 5 of the Course of Theoretical Physics. 3e (1976) Translated by J.B. Sykes and M.J. Kearsley (1980) Oxford : Pergamon Press.
. 3e (1995) Oxford: Butterworth-Heinemann
. 2e (1987) New York: Wiley
. 2e (1988) Amsterdam: North-Holland . 2e (1991) Berlin: Springer Verlag ,
; (2005) New York: Dover
2e (2000) Sausalito, Calif.: University Science
2e (1998) Chichester: Wiley
S. R. De Groot, P. Mazur (2011) Non-Equilibrium Thermodynamics, Dover Books on Physics, ISBN 978-0486647418.
Specialized topics
Kinetic theory
Vol. 10 of the Course of Theoretical Physics (3rd Ed). Translated by J.B. Sykes and R.N. Franklin (1981) London: Pergamon ,
Quantum statistical mechanics
Mathematics of statistical mechanics
Translated by G. Gamow (1949) New York: Dover
. Reissued (1974), (1989); (1999) Singapore: World Scientific
; (1984) Cambridge: University Press . 2e (2004) Cambridge: University Press
Miscellaneous
(available online here)
Historical
(1896, 1898) Translated by Stephen G. Brush (1964) Berkeley: University of California Press; (1995) New York: Dover
Translated by J. Kestin (1956) New York: Academic Press.
German Encyclopedia of Mathematical Sciences. Translated by Michael J. Moravcsik (1959) Ithaca: Cornell University Press; (1990) New York: Dover
See also
List of textbooks on classical mechanics and quantum mechanics
List of textbooks in electromagnetism
List of books on general relativity
Further reading
References
External links
Statistical Mechanics and Thermodynamics Texts Clark University curriculum development project
Lists of science textbooks
Mathematics-related lists
Physics-related lists
Textbooks
Textbooks | List of textbooks in thermodynamics and statistical mechanics | [
"Physics"
] | 535 | [
"Statistical mechanics"
] |
3,117,059 | https://en.wikipedia.org/wiki/Largest%20artificial%20non-nuclear%20explosions | There have been many extremely large explosions, accidental and intentional, caused by modern high explosives, boiling liquid expanding vapour explosions (BLEVEs), older explosives such as gunpowder, volatile petroleum-based fuels such as gasoline, and other chemical reactions. This list contains the largest known examples, sorted by date. An unambiguous ranking in order of severity is not possible; a 1994 study by historian Jay White of 130 large explosions suggested that they need to be ranked by an overall effect of power, quantity, radius, loss of life and property destruction, but concluded that such rankings are difficult to assess.
The weight of an explosive does not correlate directly with the energy or destructive effect of an explosion, as these can depend upon many other factors such as containment, proximity, purity, preheating, and external oxygenation (in the case of thermobaric weapons, gas leaks and BLEVEs).
For this article, explosion means "the sudden conversion of potential energy (chemical or mechanical) into kinetic energy", as defined by the US National Fire Protection Association, or the common dictionary meaning, "a violent and destructive shattering or blowing apart of something". No distinction is made as to whether it is a deflagration with subsonic propagation or a detonation with supersonic propagation.
Before World War I
Fall of Antwerp
On 4 April 1585, during the Spanish siege of Antwerp, a fortified bridge named "Puente Farnesio" (after the commander of the Spanish forces, Alessandro Farnese) had been built by the Spanish on the River Scheldt. The Dutch launched four large hellburners (explosive fire ships filled with gunpowder and rocks) to destroy the bridge and thereby isolate the city from reinforcement. Three of the hellburners failed to reach the target, but one containing four tons of explosive struck the bridge. It did not explode immediately, which gave time for some Spaniards, believing the ship to be a conventional fire ship, to board it to attempt to extinguish it. There was then a devastating blast that killed 800 Spaniards on the bridge, throwing bodies, rocks and pieces of metal a distance of several kilometres. A small tsunami arose in the river, the ground shook for kilometres around and a large, dark cloud covered the area. The blast was felt as far as away in Ghent, where windows vibrated.
Wanggongchang Explosion
About nine o'clock in the morning of 30 May 1626, an explosion of combustibles at the Wanggongchang Armory in Ming-era Beijing, China, destroyed almost everything within an area of surrounding the site. The estimated death toll was 20,000. About half of Beijing, from Xuanwumen Gate in the South to the modern West Chang'an Boulevard in the North, was affected. Guard units stationed as far away as Tongzhou, nearly away, reported hearing the blast and feeling the earth tremble.
Great Torrington, Devon
On 16 February 1646, 80 barrels (5.72 tons) of gunpowder were accidentally ignited by a stray spark during the Battle of Torrington in the English Civil War, destroying the church in which the magazine was located and killing several Royalist guards and a large number of Parliamentarian prisoners who were being kept there. The explosion effectively ended the battle, bringing victory to the Parliamentarians. It almost killed the Parliamentarian commander, Sir Thomas Fairfax. Great damage was caused.
Delft Explosion
About 30 tonnes of gunpowder exploded on 12 October 1654, destroying much of the city of Delft in the Netherlands. More than a hundred people were killed and thousands were injured.
Siege of Buda
On 22 July 1686, 80 tons of gunpowder exploded in the castle of Buda, killing 1500 Ottoman defenders and destroying a large portion of the defences. According to contemporary accounts, the blast wave also pushed the Danube out of its riverbed, destroying boats and causing flooding on the left (Pest) bank. The cause of the explosion was most likely a shot fired by a famed Italian artillery officer and Franciscan friar, "Fiery" Gabriel, which penetrated into the underground ammunition dump.
Destruction of the Parthenon
On 26 September 1687, the Parthenon, up until then intact, was ruined partially when an Ottoman ammunition bunker inside was struck by a Venetian mortar. 300 Turkish soldiers were killed in the explosion.
Brescia Explosion
On 18 August 1769, the Bastion of San Nazaro in Brescia, Italy was struck by lightning. The resulting fire ignited 90 tonnes of gunpowder being stored, and the subsequent explosion destroyed one-sixth of the city and killed 3,000 people.
Leiden gunpowder disaster
On 12 January 1807, a ship carrying hundreds of barrels of black powder exploded in the city of Leiden in the Kingdom of Holland. The disaster killed 151 people and destroyed more than 200 buildings in the city.
Siege of Almeida
On 26 August 1810, in Almeida, Portugal, during the Peninsular War phase of the Napoleonic Wars, French Grande Armée forces commanded by Marshal André Masséna besieged the garrison; the garrison was commanded by British Brigadier General William Cox. A shell made a chance hit on the medieval castle, within the star fortress, which was being used as the powder magazine. It ignited 4,000 prepared charges, which in turn ignited 68 tonnes of black powder and 1,000,000 musket cartridges. The ensuing explosions killed 600 defenders and wounded 300. The medieval castle was destroyed and sections of the defences were damaged. Unable to reply to the French cannonade without gunpowder, Cox was forced to capitulate the next day with the survivors of the blast and 100 cannons. The French losses during the operation were 58 killed and 320 wounded.
Fort York magazine explosion
On 27 April 1813, the magazine of Fort York in York, Ontario (now Toronto) was fired by retreating British troops during an American invasion. 13.6 tonnes of gunpowder and thirty thousand cartridges exploded sending debris, cannonballs and musketballs over the American troops. Thirty-eight soldiers, including General Zebulon Pike, the American commander, were killed and 222 were wounded.
Battle of Negro Fort
On 27 July 1816, a fort built in the War of 1812 by the British Army at Prospect Bluff in Spanish West Florida, and occupied by about 330 Maroons, Seminole, and Choctaw, was attacked by Andrew Jackson's navy as part of the First Seminole War. There was an exchange of cannon fire; the first red-hot cannonball fired by the navy entered the fort's powder magazine, which exploded. The explosion, heard more than away, destroyed the entire post which was supplied initially with "three thousand stand of arms, from five to six hundred barrels of powders and a great quantity of fixed ammunition, shot[s], shells". About 270 men, women and children lay dead. General Edmund P. Gaines later said that the "explosion was awful and the scene horrible beyond description". Reports mention no American military casualties.
Siege of Multan
On 30 December 1848, in Multan during the Second Anglo-Sikh war, a mortar shell hit 180 tonnes of gunpowder stored in a mosque, causing an explosion and many casualties.
Great fire of Newcastle and Gateshead
The 6 October 1854 great fire of Newcastle and Gateshead, UK, caused the explosion of combustibles in a bond warehouse on the quayside, which rained masonry and flaming timbers across wide areas of both cities, and left a crater with a depth of and in diameter. The explosion was heard at locations as far as away. 53 people died, and 400 to 500 were injured.
Agios Ioannis Church Explosion
On 6 November 1856 lightning struck 3,000 to 6,000 hundredweight (about 150–300 tonnes) of gunpowder stored by the Ottoman Empire in the bell tower of the Agios Ioannis church near the Palace of the Grand Master of the Knights of Rhodes in Rhodes, causing a blast that destroyed large parts of the city and killed 4,000 people.
The Battle of the Crater during the siege of Petersburg, Virginia
During the US Civil War at 4:44 a.m. on 30 July 1864, the Union Army of the Potomac besieging the Confederate Army of Northern Virginia at Petersburg, Virginia detonated a mine containing 320 kegs of gunpowder, totalling 8,000 pounds (3,600 kg) under the Confederate entrenchments. The explosion killed 278 Confederate soldiers of the 18th and 22nd South Carolina regiments and created a crater 170 feet (52 m) long, 100 to 120 feet (30 to 37 m) wide, and at least 30 feet (9 m) deep. After the explosion, attacking Union forces charged into the crater instead of around its rim. Trapped in the crater of their own making, the Union forces were easy targets for the Confederate soldiers once they recovered from the shock of the explosion. Union forces suffered 3798 casualties (killed, wounded, or captured) vs 1491 total losses for the Confederates. The Union forces failed to break through the Confederate defences despite the success of the mine. The Battle of the Crater (as it was later named) was thus a victory for the Confederacy. However, the siege continued.
Fort Fisher Magazine explosion
In 1865 during the US Civil War, after the Union Army captured Fort Fisher, North Carolina, the accidental explosion of the fort magazine resulted in an estimated 200 deaths.
Mobile magazine explosion
On 25 May 1865, in Mobile, Alabama, in the United States, an ordnance depot (magazine) exploded, killing 300 people. This event occurred six weeks after the end of the American Civil War, during the occupation of the city by victorious Federal troops.
Flood Rock explosion
On 10 October 1885 in New York City, the U.S. Army Corps of Engineers detonated 300,000 pounds (150 t) of explosives on Flood Rock, annihilating the island, in order to clear the Hell Gate tidal strait for the benefit of East River shipping traffic. The explosion sent a geyser of water in the air; the blast was felt as far away as Princeton, New Jersey. The explosion has been described as "the largest planned explosion before testing began for the atomic bomb". Rubble from the detonation was used in 1890 to fill the gap between Great Mill Rock and Little Mill Rock, merging the two into a single island, Mill Rock.
Explosion of steamship Cabo Machichaco
On 3 November 1893, in Santander, Spain, the steamship caught fire when it was docked. The ship was laden with 51 tons of dynamite and 12 tons of sulfuric acid from Galdácano, Basque Country, but authorities were unaware of this. Municipal firefighters and crew from other vessels boarded Cabo Machichaco to help fight the fire, while local dignitaries and a large crowd of people watched from the shore. At 4:45 pm a massive explosion destroyed the ship and nearby buildings and created a huge wave that washed over the seafront. Pieces of iron and débris were thrown as far as Peñacastillo, away, where a person was killed by the falling debris. 590 people were killed, and between 500 and 2,000 were injured.
Braamfontein explosion
On 19 February 1896, an explosives train at Braamfontein station in Johannesburg, loaded with between 56 and 60 tons of blasting gelatine for the gold mines of the Witwatersrand and having been standing for three and a half days in searing heat, was struck by a shunting train. The load exploded, leaving a crater in the Braamfontein rail yard long, wide and deep. The explosion was heard up to away. 75 people were killed, and more than 200 injured. Surrounding suburbs were destroyed, and roughly 3,000 people lost their homes. Almost every window in Johannesburg was broken.
USS Maine
On 15 February 1898, more than 5 tons of gunpowder exploded in the USS Maine in the Havana Harbor, Cuba, killing 266 on board. Spanish investigations found that it was likely started by spontaneous combustion of the adjacent coal bunker or accidental ignition of volatile gases. The 1898 US Navy investigation blamed an assumed mine, which caused public outrage in the United States and sympathy for the Spanish–American War.
Fontanet, Indiana
On 15 October 1907, approximately 40,000 kegs of combustible powder exploded in Fontanet, Indiana, killing between 50 and 80 people, and destroying the town. The sound of the explosion was heard over away, with damage occurring to buildings away.
DuPont Powder Mill Explosion, Pleasant Prairie, Wisconsin
On 9 March 1911, the village of Pleasant Prairie and neighbouring town of Bristol, away, were levelled by the explosion of five magazines holding 300 tons of dynamite, 105,000 kegs of black blasting powder, and five rail wagons filled with dynamite housed at a DuPont blasting powder plant. A crater deep was left where the plant was. Several hundred people were injured. The plant was closed at the time, so deaths were few, with only three plant employees being killed, E. S. "Old Man" Thompson, Clarence Brady and Joseph Flynt, and Alice Finch, who died of a heart attack after the blast rattled her home in Elgin, Illinois, forty miles away. Most buildings in a radius were rendered flat or uninhabitable. The explosion was felt within a radius of , and largely thought to be an earthquake. Residents in nearby Lake County, Illinois saw the fireball and remembering the Peshtigo fire, fled their houses and jumped into Lake Michigan. Police in Chicago scoured the streets, looking for the site of a bombing. Windows were shattered in Madison, Wisconsin, away, and the explosion was heard as far as away. A DuPont spokesman was reported as being perplexed by the coverage of the blast, quoted as saying "explosions occur every day in steel mills, flouring mills and grain elevators with hardly a line in the paper".
Alum Chine explosion
Alum Chine was a Welsh freighter (out of Cardiff) carrying 343 tons of dynamite for use during construction of the Panama Canal. It was anchored off Hawkins Point, near the entrance to Baltimore Harbor in Baltimore, Maryland. The ship exploded on 7 March 1913, killing more than 30 people, injuring about 60, and destroying a tug and two barges. Most accounts describe two distinct explosions.
World War I
HMS Princess Irene at Sheerness
On 27 May 1915, the minelayer suffered a blast. Wreckage was thrown up to , a collier boat away had its crane blown off and a crew member killed by a fragment weighing . A child ashore was killed by another fragment. A case of butter was found away. A total of 352 people were killed but one crew member survived, with severe burns. The ship had been loaded with 300 naval mines containing more than 150 tons of high explosive. An inquiry blamed faulty priming, possibly by untrained personnel.
Faversham explosion
On 2 April 1916, an explosion blew through the gunpowder mill at Uplees, near Faversham, Kent, when 200 tons of TNT ignited. 105 people died in the explosion. The munitions factory was next to the Thames estuary, and the explosion was heard across the estuary as far away as Norwich, Great Yarmouth, and Southend-on-Sea, where domestic windows were blown out and two large plate-glass shop windows shattered.
Battle of Jutland
On 31 May 1916, three British Grand Fleet battlecruisers were destroyed by cordite deflagrations initiated by armour-piercing shells fired by the Imperial German Navy's High Seas Fleet. At 16:02 was cut in two by deflagration of the forward magazine and sank immediately with all but two of its crew of 1,019. German eyewitness reports and the testimony of modern divers suggest all its magazines exploded. The wreck is now a debris field. At 16:25 was cut in two by detonation of the forward magazine and sank with all but 21 of its crew of 1,283. As the rear section capsized it also exploded. At 18:30 was cut in two by detonation of the midships magazine and sank in 90 seconds. Six of its crew survived; 1,026 men died, including Rear Admiral Hood. An armoured cruiser, , was a fourth ship to suffer an explosive deflagration at Jutland with at least 893 men killed. The rear magazine was seen to detonate followed by more explosions as the cordite flash travelled along an ammunition passage beneath its broadside guns. Eyewitness reports suggest that may also have suffered an explosion as it was lost during the night action with 857 dead, all hands. British reports say it was seen to explode. German reports speak of the ship being overwhelmed at close range and sinking. Finally, during the confused night actions in the early hours of 1 June, the German pre-dreadnought was hit by one, or possibly two, torpedoes from the British destroyer , which detonated one of Pommern gun magazines. The resulting explosion broke the ship in half and killed the entire crew of 839.
Mines on the first day of the Somme
On the morning of 1 July 1916, a series of 19 mines of varying sizes was blown to start the Battle of the Somme. The explosions constituted what was then the loudest human-made sound in history, and could be heard in London. The largest single charge was the Lochnagar mine south of La Boisselle with of ammonal explosive. The mine created a crater across and deep, with a rim high. The crater is known as Lochnagar Crater after the trench from where the main tunnel was started.
Black Tom explosion
On 30 July 1916, sabotage by German agents caused of explosives bound for Europe, along with another on Johnson Barge No. 17, to explode in Jersey City, New Jersey, a major dock in New York Harbor. There were few deaths, but about 100 injuries. Damage included buildings on Ellis Island, parts of the Statue of Liberty, and much of Jersey City.
Silvertown explosion
On 19 January 1917, parts of Silvertown in East London were devastated by a TNT explosion at the Brunner-Mond munitions factory. The explosion killed 73 people and injured hundreds. The blast was felt across London and Essex and was heard more than away, with the resulting fires visible for .
Quickborn explosion
On 10 February 1917, a chain reaction in an ammunition plant in Quickborn-Heide (northern Germany) killed at least 115 people (some sources say more than 200 people), mostly young female workers.
Bolevec explosion
Škoda Works in Bolevec, Pilsen (modern Plzeň) was the biggest ammunition plant in Austria-Hungary. A series of explosions on 25 May 1917 killed 300 workers. This event inspired Karel Čapek to write the novel (1922).
Mines in the Battle of Messines
On 7 June 1917, a series of large British mines, containing a total of more than of ammonal explosive, was detonated beneath German lines on the Messines-Wytschaete ridge. The explosions created 19 large craters, killed about 10,000 German soldiers, and were heard as far away as London and Dublin. Determining the power of explosions is difficult, but this was probably the largest planned explosion in history until the 1945 Trinity atomic weapon test, and the largest non-nuclear planned explosion until the 1947 British Heligoland detonation (below). The Messines mines detonation killed more people than any other non-nuclear deliberate explosion in history.
Halifax explosion
On 6 December 1917, and collided in the harbour of Halifax, Nova Scotia. Mont-Blanc carried 2,653 tonnes of various explosives, mostly picric acid. After the collision the ship caught fire, drifted into town, and exploded. The explosion killed 1,950 people and destroyed much of Halifax. An evaluation of the explosion's force puts it at . Halifax historian Jay White in 1994 concluded: "Halifax Harbour remains unchallenged in overall magnitude as long as five criteria are considered together: number of casualties, force of blast, radius of devastation, quantity of explosive material, and total value of property destroyed."
Chilwell Munitions Factory Explosion
On 1 July 1918, the National Shell Filling Factory No 6 (Chilwell, near Nottingham, England) was partly destroyed when 8 tons of TNT exploded in the dry mix part of the factory. Approximately 140 workers – mainly young women, known as the 'Chilwell Canaries' because contact with picric acid turned their skin yellow – were killed, though the true number has never been established. An unknown number of people were injured, though estimates are about 250. Because of the sensitivity of the subject, reports of the explosion were censored until after the Armistice. The cause of the explosion was never officially established, though present-day authorities on explosives consider it was due to a combination of factors: an exceptionally hot day, high production demands and lax safety precautions.
Split Rock explosion
On 2 July 1918, a munitions factory near Syracuse, New York, exploded after a mixing motor in the main TNT building overheated. The fire rapidly spread through the wooden structure of the main factory. Approximately 1–3 tons of TNT were involved in the blast, which levelled the structure and killed 50 workers (conflicting reports mention 52 deaths).
T. A. Gillespie Company Shell Loading Plant explosion
On 4 October 1918, an ammunition plant – operated by the T. A. Gillespie Company and located in New Jersey in the Morgan area of Sayreville in Middlesex County – exploded and caused a fire. The subsequent series of explosions continued for three days. The facility, said to be one of the largest in the world at the time, was destroyed, along with more than 300 buildings forcing reconstruction of South Amboy and Sayreville. More than 100 people died due to this accident. During a three-day period, a total of of explosives were destroyed.
Interwar period
Oppau explosion
On 21 September 1921, a BASF silo filled with 4,500 tonnes of fertilizer exploded, killing about 560, largely destroying Oppau, Germany, and causing damage more than away.
Nixon Nitration Works disaster
On 1 March 1924, an explosion destroyed a building in Nixon, New Jersey, used for processing ammonium nitrate. The explosion caused fires in surrounding buildings in the Nixon Nitration Works that contained other highly flammable materials. The disaster killed 20 people and destroyed 40 buildings.
Leeudoringstad explosion
On 17 July 1932, a train carrying 320 to 330 tons of dynamite from the De Beers factory at Somerset West to the Witwatersrand exploded and flattened the small town of Leeudoringstad in South Africa. Five people were killed and 11 injured in the sparsely-populated area.
Neunkirchen gas detonation
On 10 February 1933, a gas storage in Neunkirchen, Territory of the Saar Basin, detonated during maintenance work. The detonation could be heard at a distance of . The death toll was 68, and 160 were injured.
New London School explosion
On 18 March 1937, a natural gas leak caused an explosion, destroying the London School of New London, Texas. The disaster killed more than 295 students and teachers, making it the deadliest school disaster in American history. Letters of sympathy were sent from around the world, including a telegram from Adolf Hitler.
Hirakata ammunition dump explosion
On 1 March 1939, Warehouse No. 15 of the Imperial Japanese Army's Kinya ammunition dump in Hirakata, Osaka Prefecture, Japan, suffered a catastrophic explosion, the sound of which could be heard throughout the Keihan area. Additional explosions followed during the next few days as the depot burned, for a total of 29 explosions by 3 March. Japanese officials reported that 94 people died, 604 were injured, and 821 houses were damaged, with 4,425 households in all suffering the effects of the explosions.
World War II
Pluton
On 13 September 1939, the exploded and sank while offloading naval mines in Casablanca, in French Morocco. The explosion killed 186 men, destroyed three nearby armed trawlers, and damaged nine more.
Hercules Powder Plant
On 12 September 1940, nearly of gunpowder exploded at the Hercules Company in the Kenvil area of Roxbury, New Jersey. At least 51 people were killed, more than 100 injured, and twenty buildings flattened. It remains unknown if this was an industrial accident, or sabotage by pro-IRA or pro-Nazi factions.
SS Clan Fraser
On 6 April 1941, was moored in Piraeus Harbour, Greece. Three German Luftwaffe bombs struck the ship, igniting 350 tonnes of TNT; a barge nearby carried an additional 100 tonnes which also detonated. Royal Navy warships and attempted to tow the stricken vessel out of harbour and succeeded in getting beyond the breakwater, after the tow line had broken three times. It then exploded, levelling large areas of the port. This was witnessed by post-war author Roald Dahl, who was piloting a Hawker Hurricane fighter plane for the Royal Air Force.
HMS Hood
On 24 May 1941, sank in three minutes after the stern magazine detonated during the Battle of the Denmark Strait. The wreck has been located in three pieces, suggesting additional detonation of a forward magazine. There were only three survivors from the crew of 1,418.
HMS Barham
On 25 November 1941, was sunk by the ; 862 crew were lost. The main magazine's explosion was filmed by a Pathé News cameraman aboard the nearby HMS Valiant.
Smederevo Fortress explosion
During World War II, German invading forces in Serbia used Smederevo Fortress for ammunition storage. On 5 June 1941 it exploded, blasting through the entirety of Smederevo and reaching settlements as far as away. Much of the southern wall of the fortress was destroyed, the nearby railway station, packed with people, was blown away, and most of the buildings in the city were turned into debris. About 2,500 people died in the explosion, and half of the inhabitants were injured (approximately 5,500).
Tessenderlo Disaster
On Wednesday, 29 April 1942, an explosion destroyed the entire Produits Chimiques de Tessenderloo factory and much of the surrounding town of Tessenderlo in German-occupied Belgium. A nearby school was largely destroyed, with 60 schoolchildren losing their lives. The blast hurled steel beams as long as 15 metres into fields hundreds of metres away and left a crater 70 metres wide and 23 metres deep. The explosion occurred when factory workers tried to separate big chunks of newly arrived ammonium nitrate (200 t) using dynamite, after failing to do so using regular tools. In total, 189 people died and more than 900 were injured in the incident.
SS Surrey
On the night of 10 June 1942, the torpedoed the 8,600-ton British freighter Surrey in the Caribbean Sea. Five thousand tons of dynamite in the cargo detonated after the ship sank. The shock wave lifted U-68 out of the water as if it had suffered a torpedo hit, and both diesel engines and the gyrocompass were disabled.
SS Hatimura
On the night of 3 November 1942, torpedoes detonated the ammunition cargo of the 6,690-ton British freighter Hatimura. Both the freighter and attacking submarine were destroyed by the explosion.
Naples Caterina Costa explosion
On 28 March 1943, in the port of Naples, a fire began on Caterina Costa, an 8,060-ton motor ship carrying arms and supplies (1,000 tons of gas, 900 tons of explosives, tanks and others); the fire became uncontrollable, causing a devastating explosion. A large number of buildings around were destroyed or badly damaged. Some ships nearby caught fire and sank, and hot parts of the ship and tanks were thrown great distances. More than 600 people died and more than 3,000 were wounded.
Bombay Docks explosion
On 14 April 1944, , carrying about of explosives (among other goods), caught fire and exploded, killing about 800 people. Debris fell across the city landing miles away from the site of the explosion. The bales of cotton aboard the boat caught fire and fell from the sky causing fires in other parts of the city. The explosion was strong enough to be detected on seismographs in Simla, a city more than 1700 km from the site of the explosion.
Bergen Harbour explosion
On 20 April 1944, the Dutch steam trawler , loaded with of explosives, caught fire and exploded in Norway at the quay in the centre of Bergen. The air pressure from the explosion and the tsunami that resulted flattened whole neighbourhoods near the harbour. Fires broke out in the aftermath, leaving 5,000 people homeless. 160 people were killed, and 5,000 wounded.
SS Paul Hamilton
On 20 April 1944, the Liberty ship was attacked off Cape Bengut near Algiers by Luftwaffe bombers. The ship was destroyed within 30 seconds killing all 580 personnel aboard when the cargo of bombs and explosives detonated.
West Loch disaster
On 21 May 1944, an ammunition handling accident in Hawaii's Pearl Harbor destroyed nine amphibious vessels: six LSTs and three LCTs. Four more LSTs, ten tugs, and a net tender were damaged. Eleven buildings were destroyed ashore and nine more damaged. Between 132 and nearly 400 military personnel were killed.
4 July disaster in Aarhus
On 4 July 1944, a barge loaded with ammunition exploded in the harbour of Aarhus, Denmark, killing 39 people and injuring another 250.
Port Chicago disaster
On 17 July 1944, in Port Chicago, California, SS E. A. Bryan exploded while loading ammunition bound for the Pacific region, with an estimated of high explosive (HE), incendiary bombs, depth charges, and other ammunition. Another waiting on nearby rail cars also exploded. The total explosive content is described as between 1,600 and 2,136 tons of TNT. 320 were killed instantly, another 390 wounded. Most of the killed and wounded were African American enlisted men. After the explosion, 258 fellow sailors refused to load ordnance; 50 of these, called the "Port Chicago 50", were convicted of mutiny even though they were willing to obey any order that did not involve loading ordnance under unsafe conditions.
Cleveland East Ohio Gas explosion
On 20 October 1944, a liquefied natural gas storage tank in Cleveland, Ohio, split and leaked its contents, which spread, caught fire, and exploded. A half hour later, another tank exploded as well. The explosions destroyed , killed 130, and left 600 homeless.
USS Mount Hood
On 10 November 1944, exploded in Seeadler Harbor at Manus Island in Australian New Guinea, with an estimated 3,800 tons of ordnance material on board. Mushrooming smoke rose to , obscuring the surrounding area for a radius of approximately . Mount Hoods former position was revealed by a trench in the ocean floor long, wide, and deep. The largest remaining piece of the hull was found in the trench and measured . All 296 men aboard the ship were killed. was away and suffered extensive damage, with 23 crew killed, and 174 injured. Several other nearby ships were also damaged or destroyed. Altogether 372 were killed and 371 injured in the blast.
RAF Fauld explosion
On 27 November 1944, the RAF Ammunition Depot at Fauld, Staffordshire, became the site of the largest explosion in the UK, when 3,700 tonnes of bombs stored in underground bunkers covering exploded en masse. The explosion was caused by bombs being taken out of store, primed for use, and replaced with the detonators still installed when unused. The crater was deep and covered 5 hectares. The death toll was approximately 78, including RAF personnel, six Italian prisoners of war, civilian employees, and local people. In the similar Port Chicago disaster (above), about half the weight of bombs was high explosive. If the same is true of the Fauld Explosion, it would have been equivalent to about 2 kilotons of TNT.
Japanese aircraft carrier Unryu
On 19 December 1944, the exploded when torpedoes fired by the US submarine detonated the forward magazine.
SS John Burke
On 28 December 1944, while transporting ammunition to Mindoro, Philippines, the Liberty ship SS John Burke was hit by a Japanese kamikaze aircraft, and disintegrated in a tremendous explosion with the loss of all crew.
Japanese battleship Yamato
On 7 April 1945, after six hours of battle, 's magazine exploded as it sank, resulting in a mushroom cloud rising above the wreck, and which could be seen from Kyushu, away. 3,055 crewmen were killed.
Trinity calibration test
On 7 May 1945, 100 tons of TNT were stacked on a wooden tower and exploded to test the instrumentation prior to the test of the first atomic bomb.
1945–2000
Futamata Tunnel Explosion
On 12 November 1945 in Japan, when Allied occupation troops were trying to dispose of 530 tons of ammunition, there was an explosion in a tunnel in Soeda, Fukuoka Prefecture, Kyushu Island. According to a confirmed official report, 147 local residents were killed and 149 people injured.
Texas City Disaster
On 16 April 1947, the ship SS Grandcamp, loaded with about 2,300 tons of ammonium nitrate, exploded in port at Texas City, Texas. 581 died and more than 5,000 were injured. This is generally considered the worst industrial accident in United States history.
Heligoland "British Bang"
On 18 April 1947, British engineers attempted to destroy the abandoned German fortifications on the evacuated island of Heligoland in what became known as the "British Bang". The island had been fortified during the war with a submarine base and airfield. Roughly 4000 tons of surplus World War II ammunition were placed in various locations around the island and set off. A significant portion of the fortifications were destroyed, although some survived. According to Willmore, the energy released was 1.3×1013 J, or about 3.2 kilotons of TNT equivalent. The blast is listed in the Guinness Book of World Records under largest single explosive detonation, although Minor Scale in 1985 was larger (see below).
Ocean Liberty in Brest, France
On 28 July 1947, the Norwegian cargo ship Ocean Liberty exploded in the French port of Brest. The cargo consisted of 3,300 tonnes of ammonium nitrate in addition to paraffin and petrol. The explosion killed 22 people, hundreds were injured, 4,000–5,000 buildings were damaged.
Cádiz Explosion
On 18 August 1947, a naval ammunition warehouse containing mostly mines and torpedoes exploded in Cádiz, in southern Spain, for unknown reasons. The explosion of 200 tons of TNT destroyed a large portion of the city. Officially, the explosion killed 150 people; the real death toll is suspected to be greater.
General Vatutin cargo ship explosion in Magadan, Russia
On 19 December 1947, the Liberty class cargo ship General Vatutin exploded in the Soviet port of Magadan at Nagayeva Bay on the Russian Far East. The ship transported 3,313 tonnes of ammonal and TNT for the mining industry. Another cargo ship Vyborg, carrying 193 tonnes of chemical substances including detonators and fuse cords, also detonated from the explosion. More than 90 people were killed, more than 500 were injured. The explosion caused a tsunami with broken ice, damaging and destroying many buildings.
Mitholz, Switzerland
In December 1947, a Swiss Army ammunition dump exploded at Mitholz, Switzerland. The explosion of 3,000 tonnes of ammunition killed nine people and destroyed every house in the village.
Prüm explosion
On 15 July 1949 in the German town of Prüm, an underground bunker inside the hill of Kalvarienberg and used previously by the German Army to store ammunition, but now filled with French Army munitions, caught fire. After a mostly successful evacuation, the 500 tonnes of ammunition in the bunker exploded and destroyed large parts of the town. 12 people died and 15 were injured severely.
South Amboy powder pier explosion
The South Amboy powder pier explosion occurred on 19 May 1950. More than 420 tons of explosives in transit at the Raritan River Port in South Amboy, New Jersey detonated due to unknown causes, killing 31 people and injuring more than 350.
Cali explosion, Colombia
On 7 August 1956, seven trucks from the Colombian National Army, carrying more than 40 tons of dynamite, exploded. The explosion killed more than 1,000 people, and left a crater deep and in diameter.
Ripple Rock, British Columbia, Canada
On 5 April 1958, an underwater mountain at Ripple Rock, British Columbia, Canada was levelled by the explosion of 1,375 tonnes of Nitramex 2H, an ammonium nitrate-based explosive. This was one of the largest non-nuclear planned explosions on record, and the subject of the first Canadian Broadcasting Corporation live broadcast coast-to-coast.
Operation Blowdown
On 18 July 1963, a test blast of 50 tons of TNT in the Iron Range area of Queensland, Australia, tested the effects of nuclear weapons on tropical rainforest, military targets and ability of troops to transit through the resulting debris field.
CHASE 2, off New Jersey
On 17 September 1964, the offshore disposal of the ship Village, containing of obsolete munitions, caused unexpected detonations five minutes after sinking off New Jersey. The detonations were detected on seismic instruments around the world; the incident encouraged intentional detonation of subsequent disposal operations to determine detectability of underwater nuclear testing.
Operation Sailor Hat
A series of tests, Operation Sailor Hat, was performed off Kaho'olawe Island, Hawaii, in 1965, using conventional explosives to simulate the shock effects of nuclear blasts on naval vessels. Each test included the detonation of of high explosives.
CHASE 3 and 4, off New Jersey
On 14 July 1965, Coastal Mariner was loaded with of obsolete munitions containing of high explosives. The cargo was detonated at a depth of and created a 600-foot (200 m) water spout, but was not deep enough to be recorded on seismic instruments. On 16 September 1965, Santiago Iglesias was similarly detonated with of obsolete munitions.
Feyzin disaster, near Lyon, France
On 4 January 1966, an LPG spill occurred near Lyon, France, and resulted in a cloud of propane vapour which persisted until it was ignited by a car passing by. Several tanks erupted in a boiling liquid expanding vapour explosion, causing the deaths of 18 people, the injury of 81 and extensive damage to the site.
Medeu Dam
On 21 October 1966, a mud flow protection dam near Alma-Ata, Kazakhstan was created by a series of four preliminary explosions of 1,800 tonnes total and a final explosion of 3,600 tonnes of ammonium nitrate-based explosive. On 14 April 1967, the dam was reinforced by an explosion of 3,900 tonnes of ammonium nitrate-based explosive.
CHASE 5, off Puget Sound
On 23 May 1966, Izaac Van Zandt was loaded with of obsolete munitions containing of high explosives. The cargo was detonated off Puget Sound at a depth of .
CHASE 6, off New Jersey
On 28 July 1966, Horace Greeley was loaded with obsolete munitions and detonated off New Jersey at a depth of .
N1 launch explosion
On 3 July 1969, an N1 rocket in the USSR exploded upon impacting its launch pad at Baikonur Cosmodrome, after a turbopump exploded in one of the engines. The entire rocket contained about of kerosene and of liquid oxygen. Using a standard energy release of 43 MJ/kg of kerosene gives about 29 TJ for the energy of the explosion (about 6.93 kt TNT equivalent). Investigators later determined that as much as 85% of the fuel in the rocket did not detonate, meaning that the blast yield was likely no more than 1 kt TNT equivalent. Comparing explosions of initially unmixed fuels is difficult (being part detonation and part deflagration).
Old Reliable Mine Blast
On 9 March 1972, 2,000 tons (4 million pounds) of explosive were detonated inside three levels of tunnels in the Old Reliable Mine near Mammoth, Arizona. The blast was an experimental attempt to break up the ore body so that metals (primarily copper) could be extracted using sulfuric acid in a heap-leach process. The benefits of increased production were short-lived while the costs of managing acid mine drainage due to the sulfide ore body being exposed to oxygen continue to the present.
Flixborough disaster
On 1 June 1974, a pipe failure at the Nypro chemical plant in Flixborough, England, caused a large release of flammable cyclohexane vapour, which ignited. The resulting fuel-air explosion destroyed the plant, killing 28 people and injuring 36 more. Beyond the plant 1,821 houses and 167 shops and factories had suffered to a greater or lesser degree. Fires burned for 16 days. The explosion occurred during a weekend, otherwise the casualties would have been much greater. This explosion caused a significant strengthening of safety regulations for chemical plants in the United Kingdom.
Iri station explosion
On 11 November 1977, a freight train carrying 40 tons of dynamite in South Korea from Gwangju suddenly exploded at Iri station (present-day Iksan), Jeollabuk-do province. The cause of the explosion was accidental ignition by a drunk guard. 59 people died, and 185 others seriously wounded; altogether, more than 1,300 people were injured or killed.
Los Alfaques disaster
On 11 July 1978, an overloaded tanker truck carrying 23 tons of liquefied propylene crashed and ruptured in Spain, emitting a white cloud of ground-hugging fumes which spread into a nearby campground and discothèque before reaching an ignition source and exploding. 217 people were killed and 200 more severely burned.
Murdock BLEVEs
In 1983 near Murdock, Illinois, at least two tanker cars of a burning derailed train exploded into BLEVEs; one of them was thrown nearly .
Benton fireworks disaster
On 27 May 1983, an explosion at an illegal fireworks factory near Benton, Tennessee, killed eleven people, injured one, and caused damage within a radius of several miles. The blast created a mushroom cloud tall and was heard as far as away.
1983 Newark explosion
On 7 January 1983, an explosion in Newark, New Jersey in the Texaco oil tank farm was felt for 100–130 miles from epicenter, claiming 1 life and injuring 22–24 people.
Minor Scale and Misty Picture
Many very large detonations have been performed in order to simulate the effects of nuclear weapons on vehicles and other military material. The largest publicly known test was conducted by the United States Defense Nuclear Agency (now part of the Defense Threat Reduction Agency) on 27 June 1985 at the White Sands Missile Range in New Mexico. This test, named Minor Scale, used of ANFO, with a yield of about . Misty Picture was another similar test a few years later, slightly smaller at .
PEPCON disaster
On 4 May 1988, about of ammonium perchlorate (NH4ClO4) caught fire and set off explosions near Henderson, Nevada. A natural gas pipeline ruptured under the stored ammonium perchlorate and added fuel to the later, larger explosions. There were seven detonations in total, the largest being the last. Two people were killed and hundreds injured. The largest explosion was estimated to be equivalent to . The accident was caught on video by a broadcast engineer servicing a transmitter on Black Mountain, between Henderson and Las Vegas.
Arzamas train disaster
The Arzamas explosion, known also as Arzamas train disaster, occurred on 4 June 1988, when three goods wagons transporting hexogen to Kazakhstan exploded on a railway crossing in Arzamas, Gorky Oblast, USSR. Explosion of 118 tons of hexogen made a deep crater, and caused major damage, killing 91 people and injuring 1,500. 151 buildings were destroyed.
Ufa train disaster
On 4 June 1989, a gas explosion destroyed two trains (37 cars and two locomotives) in the USSR. At least 575 people died and more than 800 were injured.
Intelsat 708 Long March 3B launch failure
On 14 February 1996, a Chinese Long March 3B rocket veered severely off course immediately after clearing the launch tower at the Xichang Satellite Launch Center, then crashed into a nearby city and exploded on impact. The rocket did not have a flight termination system that would have allowed the vehicle to be destroyed mid-air. After the disaster, foreign media were kept in a bunker for five hours while, some alleged, the Chinese People's Liberation Army attempted to "clean up" the damage. Officials later blamed the failure on an "unexpected gust of wind" although video shows this is not the case. Xinhua News Agency initially reported 6 deaths and 57 injuries.
Enschede fireworks disaster
On 13 May 2000, 177 tonnes of fireworks exploded in Enschede, in the Netherlands, in which 23 people were killed and 947 were injured. The first explosion had the order of 800 kg TNT equivalence; the final explosion was in the range of 4,000–5,000 kg TNT.
2001–present
AZF chemical factory
On 21 September 2001, an explosion occurred at a fertilizer factory in Toulouse, France. The disaster caused 31 deaths, 2,500 seriously wounded, and 8,000 minor injuries. The blast (estimated yield of 20–40 tons of TNT, comparable in scale to the military test Operation Blowdown) was heard 80 km away (50 miles) and registered 3.4 on the Richter magnitude scale. It damaged about 30,000 buildings over about two-thirds of the city, for an estimated total cost of about €2 billion.
Ryongchon disaster
A train exploded in North Korea on 22 April 2004. According to officials, 54 people were killed and 1,249 were injured.
Seest fireworks disaster
On 3 November 2004, about 284 tonnes of fireworks exploded in Kolding, in Denmark. One firefighter was killed, and a mass evacuation of 2,000 people saved many lives. The cost of the damage was estimated at €100 million.
Texas City refinery explosion
On 23 March 2005, there was a hydrocarbon leak due to incorrect operations during a refinery startup which caused a vapour cloud explosion when ignited by a running vehicle engine. There were 15 deaths and more than 170 injured.
2005 Hertfordshire Oil Storage Terminal fire
On 11 December 2005, there was a series of major explosions at the capacity Buncefield oil depot near Hemel Hempstead, Hertfordshire, England. The explosions were heard more than away, as far as the Netherlands and France, and the resulting flames were visible for many miles around the depot. A smoke cloud covered Hemel Hempstead and nearby parts of west Hertfordshire and Buckinghamshire. There were no fatalities, but there were around 43 injuries (2 serious). The British Geological Survey estimated the equivalent yield of the explosion as 29.5 tonnes TNT.
Sea Launch failure
On 30 January 2007, a Sea Launch Zenit-3SL space rocket exploded on takeoff. The explosion consumed the roughly of kerosene and liquid oxygen aboard. This rocket was launched from an uncrewed ship in the middle of the Pacific Ocean, so there were no casualties; the launch platform was damaged and the NSS-8 satellite was destroyed.
2007 Maputo arms depot explosion
On 22 March 2007, there was a series of explosions over 2.5 hours in an arms depot in the Mozambican capital of Maputo. The incident was blamed on high temperatures. Officials confirmed 93 human fatalities and more than 300 injuries.
2008 Gërdec explosions
On 15 March 2008, at an ex-military ammunition depot in the village of Gërdec in the Vorë Municipality, Albania (14 kilometres from Tirana, the capital), US and Albanian munitions experts were preparing to destroy stockpiles of obsolete ammunition. The main explosion, involving more than 400 tons of propellant in containers, destroyed hundreds of houses within a few kilometres from the depot and broke windows in cars on the Tirana-Durrës highway. A large fire caused a series of smaller but powerful explosions that continued until 2 a.m. the next day. The explosions could be heard as far away as the Macedonian capital of Skopje, 170 km (110 mi) away.[1] There were 26 killed, 318 houses were destroyed completely, 200 buildings were seriously damaged, and 188 buildings were less seriously damaged.
2009 Cataño oil refinery fire
On the morning of 23 October 2009, there was a major explosion at the petrol tanks at the Caribbean Petroleum Corporation oil refinery and oil depot in Bayamón, Puerto Rico. The explosion was seen and heard from away and left a smoke plume with tops as high as . It caused a 3.0 earthquake and blew glass out of windows around the city. The resulting fire was extinguished on 25 October.
Ulyanovsk arms depot explosion
On 13 and 23 November 2009, 120 tons of Soviet-era artillery shells blew in two separate sets of explosions at the 31st Arsenal of the Caspian Sea Flotilla's ammunition depot near Ulyanovsk, killing ten people.
Evangelos Florakis Naval Base explosion
About 5:45 am local time on 11 July 2011, a fire at a munitions dump at Evangelos Florakis Naval Base near Zygi, Cyprus, caused the explosion of 98 cargo containers holding various types of munitions. The naval base was destroyed, as was Cyprus's biggest power plant, the "Vassilikos" power plant away. The explosion also caused 13 deaths and more than 60 injuries. Injuries were reported as far as away and damaged houses were reported as far as away. Seismometers at the Mediterranean region recorded the explosion as a M3.0 seismic event.
Cosmo Oil Refinery fire
On 11 March 2011 in Japan, the Tōhoku earthquake caused natural gas containers in the Cosmo Oil Refinery of Ichihara, Chiba Prefecture, to catch fire, destroying storage tanks and injuring six people. As it burned, several pressurized liquefied propane gas storage tanks exploded into fireballs. It was extinguished by the Cosmo Oil Company on 21 March 2011.
Texas fertilizer plant explosion
On 17 April 2013, a fire culminating in an explosion shortly before 8 p.m. CDT (00:50 UTC, 18 April) destroyed the West Fertilizer Company plant in West, Texas, United States, located north of Waco, Texas. The blast killed 15 people, injured more than 160, and destroyed over 150 buildings. The United States Geological Survey recorded the explosion as a 2.1-magnitude earthquake, the equivalent of 7.5–10 tons of TNT.
Lac-Mégantic rail disaster
On 6 July 2013, a train of 73 tank cars of light crude oil ran away down a slight incline, after being left unattended for the night, when the air brakes failed after the locomotive engines were shut down following a small fire. It derailed twelve kilometres away in Lac-Mégantic, Quebec, Canada, igniting the Bakken light crude oil from 44 DOT-111 oil cars. Approximately 3–4 minutes after the initial blast, there was a second explosion from 12 oil cars. A series of smaller blasts followed into the early morning hours, igniting the oil of a total 73 oil cars. The disaster is known to have killed 42 people; five more were missing and presumed dead.
2015 Tianjin explosions
On 12 August 2015, at 23:30, two explosions occurred in the Chinese port Tianjin at a warehouse operated by Ruihai Logistics. The more powerful explosion was estimated at 336 tons TNT equivalent. 173 people were killed, and 8 remain missing.
2016 Salawa armoury explosion
On 5 June 2016, a fire at the largest military armoury in the island nation of Sri Lanka caused a series of explosions that lasted for about 5 hours. One soldier was killed and several others were injured.
2016 San Pablito Market fireworks explosion
On 20 December 2016, a fireworks explosion occurred at the San Pablito Market in the city of Tultepec, north of Mexico City. At least 42 people were killed, and dozens injured.
2017 Kalynivka ammunition depot explosion
On 6 September 2017, an ammunition explosion occurred at ammunition depot in Kalynivka, near Vinnytsia, Ukraine.
2020 Tarragona IQOXE plant explosion
On 14 January 2020, an ethylene oxide tank exploded at the IQOXE (Chemical Industries of Ethylene Oxide) plant in Tarragona (Spain).
2020 Beirut explosion
On 4 August 2020, a warehouse containing of ammonium nitrate exploded following a fire in the Port of Beirut, Lebanon. The explosion generated a pressure wave felt more than away. Following early estimates of the yield of the explosion ranging from hundreds of tons of TNT equivalent to 1.1 kilotons, a study by researchers from the Blast and Impact Research Group at the University of Sheffield estimated the energy of the Beirut explosion to be equivalent to 0.5–1.2 kt of TNT. At least 218 people were killed, more than 7,000 injured, and about 300,000 made homeless. Much of central Beirut was devastated by the blast with property damage estimated at US$10–15 billion.
2024 Toropets drone strike
A Ukrainian drone attack on a Russian weapons depot in Toropets, Tver Oblast, caused an explosion large enough to be detected as an earthquake by monitoring stations. Local residents were told to evacuate and schools in the region were closed.
Comparison with large non-nuclear military ordnance
The most powerful non-nuclear weapons ever designed are the United States' MOAB (standing for Massive Ordnance Air Blast, tested in 2003 and used on 13 April 2017, in Achin District, Afghanistan) and the Russian "Father of All Bombs" (tested in 2007). The MOAB contains of Composition H6 explosive, which is 1.35 times as powerful as TNT, giving the bomb an approximate yield of 11 t TNT. It would require about 250 MOAB blasts to equal the Halifax explosion (2.9 kt).
Conventional explosions for nuclear testing
Large conventional explosions have been conducted for nuclear testing purposes. Some of the larger ones are listed below.
Other smaller tests include Air Vent I and Flat Top I-III series of 20 tons TNT at Nevada Test Site in 1963–64, Pre Mine Throw and Mine Throw in 1970–1974, Mixed Company 1 & 2 of 20 tons TNT, Middle Gust I-V series of 20 or 100 tons TNT in the early 1970s, Pre Dice Throw and Pre Dice Throw II in 1975, Pre-Direct Course in 1982, SHIST in 1994, and the series Dipole Might in the 1990s and 2000s. Divine Strake was a planned test of 700 tons ANFO at the Nevada Test Site in 2006, but was cancelled.
Largest accidental artificial non-nuclear explosions by magnitude
These yields are approximated by the amount of the explosive material and its properties. They are rough estimates and are not authoritative.
See also
List of nuclear weapons tests and High explosive nuclear effects testing
List of accidents and disasters by death toll
List of accidents and incidents involving transport or storage of ammunition
SS Richard Montgomery, a Liberty ship that sank in the Thames Estuary off Kent, England, in 1944, with a cargo of 1.4 kt of high explosives. As of 1st June 2024 the cargo remains undetonated.
References
Explosions | Largest artificial non-nuclear explosions | [
"Chemistry"
] | 11,208 | [
"Explosions"
] |
3,117,149 | https://en.wikipedia.org/wiki/Biomega%20%28manga%29 | is a Japanese science fiction manga written and illustrated by Tsutomu Nihei. It was first serialized in Kodansha's manga magazine Weekly Young Magazine in 2004, and later in Shueisha's Ultra Jump from 2006 to 2009; its chapters were collected in six volumes.
Plot
Set in the future, the plot follows Zoichi Kanoe and his AI companion Fuyu Kanoe, whose luminous form is integrated into the system of his motorcycle. They are agents sent by TOA Heavy Industries to retrieve humans with the ability to resist and transmute the N5S infection originating from Mars, which is spreading across the world fast, turning humans into "Drones"; disfigured, zombie-like beings.
Organizations and characters
TOA Heavy Industries
is the main rival to the DRF. They are the creators of synthetic humans and have made it their priority to collect those who have adapted to the N5S virus before the DRF does. On February 26, 3006 A.D. TOA Heavy Industries's headquarters self-destructs, leaving the synthetic humans on their own.
A synthetic human created by TOA Heavy Industries, and is on a mission to find humans that have adapted to the N5S virus. He meets Eon Green in a Maximum Security Containment Facility, in south district 17 of 9JO, where he had been dispatched. He fails to rescue Eon when she is taken by the Public Health Department. He then starts to track her down. His weapon is a powerful pistol able to rapid firing and he rides a HDC-08B-3 TOA Industries Motorcycle. He is also equipped with a linear accelerator rifle and an axe for close combat.
A holographic AI personality of the large black motorcycle ridden by Zoichi. She assists Zoichi with situational analysis as well as advising him on strategies. Like other artificial intelligence systems in the manga, she is programmed with emotions.
A female synthetic human who makes contact with Kozlov Leifnovich Grebnev while she's on a mission to find Loew Grigorievic Grebnev, one of the original founders of the Data Recovery Foundation. She has similar weapons and vehicle as Zoichi.
The male AI belonging to Nishu.
He was killed early by Higuide after an otherwise successful intrusion of a Maximum Security Containment Facility, as depicted in the "Interlink" chapter. In there he discovered the new, less virulent pseudo-N5S virus and sent his AI into orbit with this information just before his death.
A female AI that belonged to the now-deceased TOA Heavy Industries's synthetic human Go Hinoto and his destroyed motorcycle. She was sent into orbit by Go, and later fell down to Earth and was saved from DRF forces by Kozlov Leifnovic Grebnev. Soon after, she joins the Mizunoe unit.
Data Recovery Foundation
The , also known as the "DRF", was founded in 2272 under the name "Microvolt Corporation" and houses the main antagonists of the manga. They are trying to find all existing humans who have adapted to the N5S virus to use them to create their own immortals. They believe that all humans should be infected with the N5S virus, believing that it will remake some of them into the "new human race" and kill off the rest. They call this process "the baptism". After the destruction of TOA Heavy Industries's headquarters, they proclaim themselves the new world government.
The overlord (or, "Matriarch") of the DRF and also the second oldest person in the world. She is an esper who possesses an advanced form of psychometry which not only allows her to read the "thoughts" of any organic material, whether living or long-since fossilized within inorganic materials, but to "download" such knowledge into herself as well as "hack" and manipulate the source of it (this ability manifesting in white luminescent "worms" that extend from her body and enter the target). As a child working for Microvolt, she used this to subdue Narain when the manifestation of his psychic abilities drove him insane; while her powers did help him regain control of his mind and powers, he has been terrified of her ever since, especially when her control over her own power (ironically) drove her mad. Because her powers work best upon organic material she is reflexively antagonized by anything non-organic, which develops into outright misanthropic technophobia.
The
Two superhuman swordsmen who serve Niardi exclusively. They are cyborgs encased in jet-black armor reminiscent of samurai, and carry no weapons other than high-tech katana slung over their shoulders (similar to the "Safeguard Swords" seen in Blame!). The Guardian of the Left is sent to kill Eon Green (but is killed by Zoichi) while the Guardian of the Right protects Niardi during her attack upon the PHS, where he kills Dr. Wildenstein and is later killed by Higuide.
Public Health Department
The , also known as the "PHS", is a subsidiary of the DRF. Their headquarters is a monadnock. The PHS later turns against the DRF due to Niardi's outrageous intentions, but is quickly overrun by DRF forces.
The of the PHS, originally recruited by Niardi. Fearing Niardi and her powers as well as his own mortality, he changed himself repeatedly, hoping to immunize himself against her mind-reading; his current form is a huge, possibly mutated creature with several tentacles. He was the one who ordered the destruction of TOA Heavy Industries.
A young woman that works for the PHS. She can cover herself in a semi-organic body suit that can be used for both offense and defense, and also possesses some form of psychokinesis. She is first seen taking Eon Green with her from the MSCF of 9JO. Zoichi later meets her in her human form and spends some time with her without knowing who she is. She appears to have some moral qualms regarding orders given her, but never questions her superiors.
An extremely powerful Patrol Inspector working under Narain. He is highly proficient in the use of bladed weapons and combat techniques, as demonstrated when he is chosen by Narain to execute a fellow Patrol Inspector in a "duel" who was spying for Niardi, and has even succeeded in killing TOA Heavy Industries's agent Go Hinoto. He has also shown impressive agility, dodging a fully charged Gravitational Round Emission, and destroying multiple "War-Engines" (large battle mecha with enormous destructive capability) in a single battle.
A brilliant scientist working for the PHS who serves under General Narein. Although he steals the Gravitation Emission Weapon Data from Dr. Mamura Kurokawa of TOA Heavy Industries, he is proficient in other fields, as he manages to modify the N5S virus for the PHS's use. He also learns how to create synthetic humans, and when combining the data, he learns how to use the N5S virus for battle purposes among skilled soldiers or even how to reverse its effects.
Immortals
The immortals are humans who have adapted to the N5S virus on a genetic level (having 24 pairs of chromosomes after infection), integrating it into their cell structure and giving them inhuman abilities: advanced regeneration and longevity. Called accommodators in US version.
Born Vief Chiena, is a 17-year-old seemingly immortal girl who has adapted herself to the N5S virus. She is parentless and lives with Kozlov Leifnovich Grebnev in her grandfather's house in south district 17 of 9JO. She has a super-regenerative healing factor. She is taken into custody by the Public Health Department, after which she rarely appears in the manga. She carries some sort of spore in her that can turn all Drones back to normal humans.
Another female immortal. She was found on earth about 700 years before the beginning of the story, then being already 300 years old. It was discovered that she had a 24th chromosome, and from time to time her body would secrete small amounts of an unknown substance, similar to plastic. She is the woman found on Mars in the beginning of the story, and afterwards she is never seen aside from flash-backs.
Others
A clone of a scientist who co-found Data Recovery Foundation. The scientist loved Reload, so he created a modified clone of himself that was immortal and compatible with Reload. After transferring his brain to the clone body, he pitied his clone, so he transferred the clone's brain into the body of his pet bear, which was a prototype of the immortal clone body. As a bear he can walk upright, talk and even wield weapons like a human would. He lived with Ion Green and tried to protect her when a patrol officer from the Public Health Department came to get her. He befriends both Zoichi and Nishu after an unfriendly start with both. He saves the AI, Tyra Hinoto, from falling into the hands of the DRF. In the end, it is revealed that the new string world is created from his own consciousness, and he played a crucial role to defeat Niardi.
Publication
Biomega, written and illustrated by Tsutomu Nihei, was first serialized in Kodansha's manga magazine Weekly Young Magazine from June 14 to September 6, 2004. Kodansha only released one volume on November 5, 2004. The manga was later transferred to Shueisha's Ultra Jump, where it ran from May 19, 2006, to January 19, 2009. Shueisha collected its chapters in six tankōbon volumes, released from January 19, 2007, to March 19, 2009. Kodansha published a three-volume deluxe edition from April 30 to August 9, 2021.
In North America, the manga was licensed for English release by Viz Media. The six volumes were released from February 2, 2010, to May 17, 2011.
Volumes
Reception
In a list of "10 Great Zombie Manga", Anime News Network's Jason Thompson placed Biomega in third place, calling it "the greatest science-fiction virus zombie manga ever".
Notes
References
External links
Fiction about artificial intelligence
Biopunk anime and manga
Biorobotics in fiction
Cyberpunk anime and manga
Fiction about cyborgs
Fiction about immortality
Kodansha manga
Fiction about nanotechnology
Post-apocalyptic anime and manga
Fiction about robots
Seinen manga
Shueisha manga
Thriller anime and manga
Fiction about viral outbreaks
Viz Media manga
Zombies in popular culture | Biomega (manga) | [
"Materials_science",
"Biology"
] | 2,212 | [
"Fiction about nanotechnology",
"Nanotechnology",
"Fiction about cyborgs",
"Cyborgs"
] |
3,117,240 | https://en.wikipedia.org/wiki/Gamma%20Cassiopeiae | Gamma Cassiopeiae, Latinized from γ Cassiopeiae, is a bright star at the center of the distinctive "W" asterism in the northern circumpolar constellation of Cassiopeia. Although it is a fairly bright star with an apparent visual magnitude that varies from 1.6 to 3.0, it has no traditional Arabic or Latin name. It sometimes goes by the informal name Navi. It was observed in 1866 by Angelo Secchi, the first star ever observed with emission lines. It is now considered a Be star.
Gamma Cassiopeiae is also a variable star and a multiple star system. Based upon parallax measurements made by the Hipparcos satellite, it is located at a distance of roughly 550 light-years from Earth. Together with its common-proper-motion companion, HD 5408, the system could contain a total of eight stars. It is one of the highest multiplicity systems known.
Physical properties
Gamma Cassiopeiae is an eruptive variable star, whose apparent magnitude changes irregularly from 1.6 at its brightest to 3.0 at its dimmest. It is the prototype of the class of Gamma Cassiopeiae variable stars. In the late 1930s it underwent what is described as a shell episode and the brightness increased to above magnitude 2.0, then dropped rapidly to 3.4. It has since been gradually brightening back to around 2.2. At maximum intensity, γ Cassiopeiae outshines both Schedar (α Cas; magnitude 2.25) and Caph (β Cas; 2.3).
Gamma Cassiopeiae is a rapidly spinning star with a projected rotational velocity of 472 km s−1, giving it a pronounced equatorial bulge. When combined with the star's high luminosity, the result is the ejection of matter that forms a hot circumstellar disk of gas. The emissions and brightness variations are apparently caused by this "decretion disk".
The spectrum of this massive star matches a stellar classification of B0.5 IVe. A luminosity class of IV identifies it as a subgiant star that has reached a stage of its evolution where it is exhausting the supply of hydrogen in its core region and transforming into a giant star. The 'e' suffix is used for stars that show emission lines of hydrogen in the spectrum, caused in this case by the circumstellar disk. This places it among a category known as Be stars; in fact, the first such star ever to be so designated. It has 17 times the Sun's mass and is radiating as much energy as 34,000 Suns. At this rate of emission, the star has reached the end of its life as a late O-type main sequence star after a relatively brief 8 million years. The outer atmosphere has an intense effective temperature of 25,000 K, which is causing it to glow with a blue-white hue.
X-ray emission
Gamma Cassiopeiae is the prototype of a small group of stellar sources of X-ray radiation that is about 10 times stronger than emitted from other B or Be stars. The character of the X-ray spectrum is Be thermal, possibly emitted from plasmas of temperatures up to least ten million kelvins, and shows very short term and long-term cycles. Historically, it has been held that these X-rays might be excited by matter originating from the star, from a hot wind or a disk around the star, accreting onto the surface of a degenerate companion, such as a white dwarf or neutron star. However, there are difficulties with either of these hypotheses. For example, it is not clear that enough matter can be accreted by a white dwarf, at the distance of the purported secondary star implied by the orbital period, sufficient to power an X-ray emission of nearly 1033 erg/s or 100 YW. A neutron star could easily power this X-ray flux, but X-ray emission from neutron stars is known to be non-thermal, and thus in apparent variance with the spectral properties.
Evidence suggests that the X-rays may be associated with the Be star itself or caused by some complex interaction between the star and surrounding decretion disk. One line of evidence is that the X-ray production is known to vary on both short and long time scales with respect to various UV line and continuum changes associated with a B star or with circumstellar matter close to the star. Moreover, the X-ray emissions exhibit long-term cycles that correlate with the light curves in the visible wavelengths.
Gamma Cassiopeiae exhibits characteristics consistent with a strong disordered magnetic field. No field can be measured directly from the Zeeman effect because of the star's rotation-broadened spectral lines. Instead, the presence of this field is inferred from a robust periodic signal of 1.21 days that suggests a magnetic field rooted on the rotating star's surface. The star's UV and optical spectral lines show ripples moving from blue to red over several hours, which indicates clouds of matter being held frozen over the star's surface by strong magnetic fields. This evidence suggests that a magnetic field from the star is interacting with the decretion disk, resulting in the X-ray emission. A disk dynamo has been advanced as a mechanism to explain this modulation of the X-rays. However, difficulties remain with this mechanism, among which is that there are no disk dynamos known to exist in other stars, rendering this behavior more difficult to analyze.
Companions
Gamma Cassiopeiae has three faint companions, listed in double star catalogues as components B, C, and D. Star B is about 2 arc-seconds distant and magnitude 11, and has a similar space velocity to the bright primary, making it likely to be physically associated. Component C is magnitude 13, nearly an arc-minute distant, and is listed in Gaia Early Data Release 3 as having a very different proper motion and being much more distant than Gamma Cassiopeiae. Finally, component D, about 21 arc-minutes distant, is the naked-eye star HR 266 (HD 5408), itself a quadruple system.
Gamma Cassiopeiae A, the bright primary, itself contains a spectroscopic binary with an orbital period of about 203.5 days and an eccentricity alternately reported as 0.26 and "near zero." The mass of the companion is believed to be about that of the Sun, but its nature is unclear. It has been proposed that it is a degenerate star or a hot helium star, but it seems unlikely that it is a normal star. Therefore, it is likely to be more evolved than the primary and to have transferred mass to it during an earlier stage of evolution. Additionally, Hipparcos data show a "wobble" with an amplitude of about 150 mas, that may correspond to the orbit of a third star. This star would have an orbital period of at least 60 years.
Names
γ Cassiopeiae (Latinized to Gamma Cassiopeiae) is the object's Bayer designation, and it has the Flamsteed designation 27 Cassiopeiae.
The Chinese name Tsih, "the whip" (), is commonly associated with this star. The name however originally referred to Kappa Cassiopeiae, and Gamma Cassiopeiae was just one of four horses pulling the chariot of legendary charioteer Wangliang. This representation was later changed to make Gamma the whip.
The star was used as an easily identifiable navigational reference point during space missions and American astronaut Virgil Ivan "Gus" Grissom nicknamed the star Navi after his own middle name spelled backwards.
See also
Iota Ursae Majoris, informally named Dnoces for astronaut Ed White
Gamma Velorum, informally named Regor for astronaut Roger B. Chaffee
Sh 2-185, an H II region centered on Gamma Cassiopeiae
References
External links
Philippe Stee's homepage: Hot and Active Stars Research
Gamma Cassiopeiae and the Be Stars.
A New Class of X-ray Star?
Gamma Cas and Friends, Astronomy Picture of the Day, 2009 December 24
Cassiopeiae, Gamma
B-type subgiants
Cassiopeia (constellation)
Gamma Cassiopeiae variable stars
8
Spectroscopic binaries
Be stars
Cassiopeiae, 27
0264
005934
004427
BD+59 0144
Navi
Gus Grissom | Gamma Cassiopeiae | [
"Astronomy"
] | 1,749 | [
"Cassiopeia (constellation)",
"Multiple stars",
"Sky regions",
"Constellations"
] |
3,117,270 | https://en.wikipedia.org/wiki/Veronese%20map | The Veronese map of degree 2 is a mapping from to the space of symmetric matrices defined by the formula:
Note that for any .
In particular, the restriction of to the unit sphere factors through the projective space , which defines Veronese embedding of . The image of the Veronese embedding is called the Veronese submanifold, and for it is known as the Veronese surface.
Properties
The matrices in the image of the Veronese embedding correspond to projections onto one-dimensional subspaces in . They can be described by the equations:
In other words, the matrices in the image of have unit trace and unit norm. Specifically, the following is true:
The image lies in an affine space of dimension .
The image lies on an -sphere with radius .
Moreover, the image forms a minimal submanifold in this sphere.
The Veronese embedding induces a Riemannian metric , where denotes the canonical metric on .
The Veronese embedding maps each geodesic in to a circle with radius .
In particular, all the normal curvatures of the image are equal to .
The Veronese manifold is extrinsically symmetric, meaning that reflection in any of its normal spaces maps the manifold onto itself.
Variations and generalizations
Analogous Veronese embeddings are constructed for complex and quaternionic projective spaces, as well as for the Cayley plane.
Notes
References
Cecil, T. E.; Ryan, P. J. Tight and taut immersions of manifolds Res. Notes in Math., 107, 1985.
K. Sakamoto, Planar geodesic immersions, Tohoku Math. J., 29 (1977), 25–56.
Differential geometry
Minimal surfaces | Veronese map | [
"Chemistry"
] | 367 | [
"Foams",
"Minimal surfaces"
] |
3,117,278 | https://en.wikipedia.org/wiki/Alpha%20Lupi | Alpha Lupi (α Lupi, α Lup) is a blue giant star, and the brightest star in the southern constellation of Lupus. According to the Bortle Dark-Sky Scale, its apparent visual magnitude of 2.3 makes it readily visible to the naked eye even from highly light-polluted locales. Based upon parallax measurements made during the Hipparcos mission, the star is around from the solar system. It is one of the nearest supernova candidates.
Characteristics
Alpha Lupi is a giant star with a stellar classification of B1.5 III. It has about ten times the mass of the Sun yet is radiating 18,000 times the Sun's luminosity. The outer atmosphere has an effective temperature of 24,550 K, which gives it the blue-white glow of a B-type star. In 1956 it was identified as a Beta Cephei variable by Bernard Pagel and colleagues, which means it undergoes periodic changes in luminosity because of pulsations in the atmosphere. The variability period is 0.29585 days, or just over 7 hours, 6 minutes. The magnitude varies by about 0.05 magnitudes, or about 5% of its brightness. A 14th magnitude star situated 26" from Alpha Lupi is listed as a companion in double star catalogues.
This star is a proper motion member of the Upper Centaurus–Lupus sub-group in the Scorpius–Centaurus OB association, the nearest such co-moving association of massive stars to the Sun. This is a gravitationally unbound stellar association with an estimated age of 16–20 million years. The association is also the source of a bubble of hot gas that contains the Sun, known as the Local Bubble.
Visibility
Visible from the Southern Hemisphere for much of the year, it can also be viewed for a shorter season from the northern tropics and from parts of the northern subtropical latitudes.
Nomenclature
α Lupi (Latinised to Alpha Lupi) is the star's Bayer designation. It has no traditional names that have been approved as proper by the IAU, nor does it have a widely used colloquial name. This makes it the brightest star in the night sky with neither a proper name nor a colloquial one.
In Chinese, Kekouan (), meaning Imperial Guards, refers to an asterism consisting of α Lupi, γ Lupi, δ Lupi, κ Centauri, β Lupi, λ Lupi, ε Lupi, μ Lup, π Lupi, and ο Lupi. Consequently, the Chinese name for α Lupi itself is (, .).
R. H. Allen described this star as having the Chinese name Yang Mun or Men (南門), meaning "the South Gate", in his work Star-Names and their Meanings. In Chinese astronomy, 南門 is located in Horn mansion and consisted of α and ε Centauri. It was referred to as Yang Mun, meaning "the south Gate". Allen also suggested that the Babylonian name for the star was "Kakkab Su-gub Gud-Elim" (Star Left Hand of the Horned Bull).
Notes
References
Lupus (constellation)
Lupi, Alpha
Beta Cephei variables
B-type giants
Upper Centaurus Lupus
5469
129056
071860
Durchmusterung objects | Alpha Lupi | [
"Astronomy"
] | 698 | [
"Constellations",
"Lupus (constellation)"
] |
3,117,288 | https://en.wikipedia.org/wiki/Eta%20Centauri | Eta Centauri, Latinized from η Centauri, is a star in the southern constellation of Centaurus. It has an apparent visual magnitude of +2.35 and is located at a distance of around .
The stellar classification of this star is B1.5 Vne, indicating that it is a B-type main sequence star. The 'n' suffix means that the absorption lines are broadened from rapid rotation and the 'e' that it shows emission lines in its spectrum. It has a projected rotational velocity of 330 km s−1 and completes a full rotation in less than a day.
As a Be star, it has variable emissions in its hydrogen spectral lines. This emission can be modelled by a decretion disk of gas that has been ejected from the star by its rapid rotation and now follows a near-Keplerian orbit around the central body. Its brightness is also slightly variable, and it is classified as a Gamma Cassiopeiae variable star with multiple periods of variability. The International Variable Star Index lists Eta Centauri as both a Gamma Cassiopeiae variable and a Lambda Eridani variable with variations caused by its rotation and pulsations.
Eta Centauri has about 12 times the mass of the Sun, placing it above the dividing line between stars that evolve into white dwarfs and those that turn into supernovae. It is radiating 8,700 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 25,700 K. At this temperature, the star glows with the blue-white hue common to B-type stars. Eta Centauri is a proper motion member of the Upper Centaurus–Lupus sub-group in the Scorpius–Centaurus OB association, the nearest such co-moving association of massive stars to the Sun.
In traditional Chinese astronomy, Eta Centauri was known as (meaning: the Second (Star) of Koo Low).
References
External links
Centaurus
Centauri, Eta
Be stars
Gamma Cassiopeiae variable stars
B-type main-sequence stars
127972
Upper Centaurus Lupus
Lambda Eridani variables
071352
5440
Durchmusterung objects | Eta Centauri | [
"Astronomy"
] | 447 | [
"Centaurus",
"Constellations"
] |
3,117,295 | https://en.wikipedia.org/wiki/Manifesto%20of%20Race | The "Manifesto of Race" (), otherwise referred to as the Charter of Race or the Racial Manifesto, was an Italian manifesto promulgated by the government of Benito Mussolini on 14 July 1938. Its promulgation was followed by the enactment, in October 1938, of the Racial Laws in Fascist Italy and the Italian Empire.
The anti-Semitic laws stripped the Italian Jews of their Italian citizenship, and they also stripped them of their governmental and professional positions. The manifesto demonstrated the substantial influence of Adolf Hitler over Benito Mussolini since Fascist Italy's growing relations with Nazi Germany, following the Second Italo-Ethiopian War. Mussolini had earlier issued statements ridiculing especially the racial policies and theories of the Nazi Party (NSDAP), and highly contradictory statements regarding antisemitism and Italian Jews, many of which had supported the National Fascist Party (PNF) earlier throughout the dictatorship. Starting with the manifesto, the National Fascist Party took a course considerably more in line with the ideology of German Nazism.
History
Prior to 1938 there had not been any race laws promulgated in the Kingdom of Italy during the previous years of Benito Mussolini's dictatorship (1922 onwards). Mussolini had held the view that a small contingent of Italian Jews had lived in Italy "since the days of the Kings of Rome" (a reference to the Benè Romi, or Italian-rite Jews) and should "remain undisturbed". There were even some Jews in the National Fascist Party, such as Ettore Ovazza who in 1935 founded the Jewish Fascist paper La Nostra Bandiera. Among the 180 signers of the "Manifesto of Race" were two medical doctors (S. Visco and N. Fende), an anthropologist (L. Cipriani), a zoologist (E. Zavattari), and a statistician (F. Savorgnan).
In recognition of both their past and future contributions and for their service as subjects of the Italian Empire since the 1880s, Rome passed a decree in 1937 distinguishing Eritreans from Ethiopians and other subjects of the newly-founded colonial empire in a divide-and-conquer fashion. In the Kingdom of Italy, Eritreans were to be addressed as "Africans" and not as "natives", as was the case with Ethiopian peoples subjected to the colonial rule of the Italian Empire from 1936 onwards. The "Manifesto of Race", published in July 1938, declared the Italians to be descendants of the Aryan race. It targeted races that were seen as inferior (i.e. not of Aryan descent). In particular, Jews were banned from many professions. Under the Racial Laws of 1938-1943, sexual relations and marriages between Italians, Jews, and Africans were forbidden. Jews were banned from positions in banking, government, and education, as well as having their properties confiscated.
On 13 July 1938 the Kingdom of Italy promulgated a publication mistitled "Manifesto of the Racial Scientists"
which mixed biological racism with history; it declared that Italy was a country populated by people of Aryan origin, that Italians belonged to the Aryan race, that Jews did not belong to the Italian race, and that it was necessary to distinguish between Europeans and Semites, Hamites, black Africans, and other non-Europeans. The manifesto encouraged Italians to be racist. The press and periodicals in Fascist Italy often published material that showed caricatures of Jews and Africans. However, even after the promulgation of the Racial Laws, Mussolini continued to make contradictory statements about race. After the fall of Mussolini and the Fascist regime on 25 July 1943, the Badoglio government suppressed the Racial Laws. They remained enforced and were made more severe in the territories ruled by the Italian Social Republic (1943–1945) until the end of the Second World War.
Motivations
The Italo-German alliance was greatly bound by the two countries' shared political philosophy of fascism as a form of "progressive reaction" against the modern world—both Mussolini and Hitler despised modern-style humanistic liberal democracy, but lauded their own ideas of fascism as the fulfillment of modern politics and the embodiment of the popular will. Hitler was captivated and personally inspired by the 1922 March on Rome and envisioned himself at the head of a similar march on Berlin. Thus, Mussolini increasingly decided to harmonize Italian Fascism with German Nazism by introducing anti-Semitic laws in Italy as evidence of his good faith towards Hitler. He conceived it, at least partially and tactically, as an offering calculated to solidify the Italo-German alliance. In Italian Fascist literature and periodicals, a shift toward a less refined racism, accentuating the biological, Indo-European element occurred, emphasizing the ancient Latins and Romans as a nucleus of warlike Aryans closely related to the Celts and other Indo-European ethnic groups; therefore, Italian Fascist nationalism merged with the doctrine of Aryan racism.
After considerable resistance, Nazi influence began to penetrate some intellectual circles in the Kingdom of Italy. In general, however, there was a concerted effort to distinguish Fascist "racism", allegedly of "culturalist" variety, from that emanating from the Germanic realm. Giovanni Gentile, for example, despised the introduction of biological racism into Italian Fascism, and the same can be said of the majority of the early theoreticians of intellectual Fascism. Yet the concern for a corporate national identity, as opposed to what Gentile called the "solipsist ego" enshrined by demo-liberal politics, was always part of the Italian Fascist worldview. In any case, it was not unusual for Fascist intellectuals to oppose themselves to the more excessive and irrational components of Ariosophy, before the outbreak of World War II.
Criticism and unpopularity
For the most part, the Racial Laws were met with disapproval from not just ordinary Italian citizens but also members of the National Fascist Party themselves. On one occasion, an Italian Fascist scholar questioned Mussolini over the treatment his Jewish friends were receiving after the promulgation of the Racial Laws, which prompted Mussolini to say: "I agree with you entirely. I don't believe a bit in the stupid anti-Semitic theory. I am carrying out my policy entirely for political reasons." William Shirer in The Rise and Fall of the Third Reich suggests that Mussolini enacted the Racial Laws in order to appease his German allies, rather than to satisfy any genuine anti-Semitic sentiment among the Italian people.
Indeed, prior to 1938 and the Pact of Steel alliance, Mussolini and many notable Italian Fascists had been highly critical of Nordicism, biological racism, and anti-Semitism, especially the virulent and violent anti-Semitism and biological racism that could be found in the ideology of Nazi Germany. Many early supporters of Italian fascism, including Mussolini's mistress, the writer and socialite Margherita Sarfatti, were in fact middle-class or upper middle-class Italian Jews. Nordicism and biological racism were often considered incompatible with the early ideology of Italian fascism; Nordicism inherently subordinated the Italians themselves and other Mediterranean peoples beneath the Germans and Northwestern Europeans in its proposed racial hierarchy, and early Italian Fascists, including Mussolini, viewed race as a cultural and political invention rather than a biological reality.
In 1929, Mussolini noted that Italian Jews had been a demographically small yet culturally integral part of Italian society since Ancient Rome. His views on Italian Jews were consistent with his early Mediterraneanist perspective, which suggested that all Mediterranean cultures, including the Jewish culture, shared a common bond. He further argued that Italian Jews had truly become "Italians" or natives to Italy after living for such a long period in the Italian Peninsula. However, Mussolini's views on race were often contradictory and quick to change when necessary, and as Fascist Italy became increasingly subordinate to Nazi Germany's interests, Mussolini began adopting openly racial theories borrowed from or based on Nazi racial policies, leading to the introduction of the anti-Semitic Racial Laws. Historian Federico Chabod argued that the introduction of the Nordicist-influenced Racial Laws was a large factor in the decrease of public support among Italians for Fascist Italy, and many Italians viewed the Racial Laws as an obvious imposition or intrusion of German values into Italian culture, and a sign that Mussolini's power and the Fascist regime were collapsing under Nazi German influence.
See also
The Holocaust in Italy
Nuremberg Laws
References
Sources
Gregor, A. James; The Search for Neofascism, New York, Cambridge University Press (2006).
Gregor, A. James; Mussolini's Intellectuals: Fascist Social and Political Thought, Princeton, Princeton University Press (2005).
Wiskemann, Elizabeth; Fascism in Italy: Its Development and Influence, New York, St. Martins Press (1969).
Renzo De Felice: The Jews in Fascist Italy. Enigma Books 2001, .
External links
1938 documents
1938 in Italy
1938 in Judaism
1938 in law
July 1938 events in Europe
Antisemitism in Italy
Aryanism
Historical definitions of race
Italian fascist works
Legal history of Italy
Race and law
Scientific racism
The Holocaust in Italy
Manifestos | Manifesto of Race | [
"Biology"
] | 1,837 | [
"Biology theories",
"Obsolete biology theories",
"Scientific racism"
] |
3,117,301 | https://en.wikipedia.org/wiki/Epsilon%20Centauri | Epsilon Centauri (ε Cen, ε Centauri) is a star in the southern constellation of Centaurus. It is one of the brightest stars in the constellation with a slightly variable apparent visual magnitude of +2.30. Parallax measurements put it at a distance of around from Earth.
In Chinese, (), meaning Southern Gate, refers to an asterism consisting of ε Centauri and α Centauri. Consequently, the Chinese name for ε Centauri itself is (, .)
ε Centauri is a massive star with nearly 12 times the mass of the Sun. The spectrum matches a stellar classification of B1 III, indicating this is an evolved giant star. It is radiating more than 15,000 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 24,000 K, giving it the blue-white hue of a B-type star. This is classified as a Beta Cephei type variable star with a primary period of 0.16961 days (4 hours 4 minutes), completing 5.9 cycles per day. During each cycle, the brightness of the star varies from apparent magnitude +2.29 to +2.31.
This star is a proper motion member of the Lower Centaurus–Crux sub-group in the Scorpius–Centaurus OB association, the nearest such association of co-moving massive stars to the Sun. Epsilon Centauri is a relatively young star, with an age of around 16 million years.
The IAU has not assigned a proper name to this star.
References
Centaurus
Centauri, Epsilon
Beta Cephei variables
B-type giants
Lower Centaurus Crux
Nán Mén yī
5132
118716
066657
CD-52 06655 | Epsilon Centauri | [
"Astronomy"
] | 364 | [
"Centaurus",
"Constellations"
] |
3,117,324 | https://en.wikipedia.org/wiki/Beta%20Gruis | Beta Gruis (β Gruis, abbreviated Beta Gru, β Gru), formally named Tiaki , is the second brightest star in the southern constellation of Grus. It was once considered the rear star in the tail of the constellation of the (Southern) Fish, Piscis Austrinus: it, with Alpha, Delta, Theta, Iota, and Lambda Gruis, belonged to Piscis Austrinus in medieval Arabic astronomy.
Nomenclature
β Gruis (Latinised to Beta Gruis) is the star's Bayer designation.
It bore the traditional Tuamotuan name of Tiaki. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name Tiaki for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning Crane, refers to an asterism consisting of Beta Gruis, Alpha Gruis, Epsilon Gruis, Eta Gruis, Delta Tucanae, Zeta Gruis, Iota Gruis, Theta Gruis, Delta² Gruis and Mu¹ Gruis. Consequently, Beta Gruis itself is known as (, ). The Chinese name gave rise to another English name, Ke.
Properties
Beta Gruis is a red giant star on the asymptotic giant branch with an estimated mass of about 2.4 times that of the Sun and a surface temperature of approximately 3,500 K, just over half the surface temperature of the Sun. This low temperature accounts for the dull red color of an M-type star. The total luminosity is about 3,200 times that of the Sun, and it has 150 times the Sun's radius.
It is one of the brightest stars at infrared and near-infrared wavelenghts. At the K band, it is the fifth-brightest star in the night sky.
Alan William James Cousins announced that Beta Gruis is a variable star in 1952.
Beta Gruis is a semiregular variable (SRb) star that varies in magnitude by about 0.4. It varies between intervals when it displays regular changes with a 37-day periodicity and times when it undergoes slow irregular variability.
References
External links
MSN Encarta (Archived 2009-10-31)
M-type giants
Semiregular variable stars
Asymptotic-giant-branch stars
Grus (constellation)
Gruis, Beta
Durchmusterung objects
214952
112122
8636
Tiaki | Beta Gruis | [
"Astronomy"
] | 531 | [
"Grus (constellation)",
"Constellations"
] |
3,117,330 | https://en.wikipedia.org/wiki/Zeta%20Centauri | Zeta Centauri, Latinized from ζ Centauri, is a binary star system in the southern constellation of Centaurus. It has the proper name Alnair , from . With a combined apparent visual magnitude of +2.55, it is one of the brighter members of the constellation. This system is close enough to the Earth that its distance can be measured directly using the parallax technique. This yields a value of roughly , with a 1.6% margin of error. It is drifting further away with a radial velocity of +6.5 km/s.
In Chinese, (), meaning Arsenal, refers to an asterism consisting of ζ Centauri, η Centauri, θ Centauri, 2 Centauri, HD 117440, ξ1 Centauri, γ Centauri, τ Centauri, D Centauri and σ Centauri. Consequently, the Chinese name for ζ Centauri itself is (, .)
ζ Cen is a double-lined spectroscopic binary system, which indicates that the orbital motion was detected by shifts in the absorption lines of their combined spectra caused by the Doppler effect. The two stars orbit each other over a period of slightly more than eight days with an orbital eccentricity of about 0.5. The estimated angular separation of the pair is 1.4 mas.
At an estimated age of 40 million years, the primary component of this system appears to be in the subgiant stage of its evolution with a stellar classification of B2.5 IV. It is a large star with nearly 8 times the mass of the Sun and close to 6 times the Sun's radius. This star is rotating rapidly with a projected rotational velocity of .
References
B-type subgiants
Spectroscopic binaries
Centaurus
Centauri, Zeta
Durchmusterung objects
121263
068002
5231 | Zeta Centauri | [
"Astronomy"
] | 391 | [
"Centaurus",
"Constellations"
] |
3,117,334 | https://en.wikipedia.org/wiki/Delta%20Centauri | Delta Centauri, Latinized from δ Centauri, is a star in the southern constellation of Centaurus. The apparent visual magnitude of this star is +2.57, making it readily visible to the naked eye. Based upon parallax measurements, it is located at a distance of about from the Earth. The star is drifting further away with a radial velocity of +11 km/s.
Properties
δ Centauri is a shell star, with a distinctive spectrum created by material thrown off into a disk by its rapid rotation. It is also a variable star whose brightness varies from magnitude +2.51 to +2.65. It has been classified as a γ Cassiopeiae type variable. The energy from this star is being radiated at an effective temperature of over 22,000 K from the outer envelope, giving it the blue-white hue of a B-type star. It has a radius of 6.5 times the radius of the Sun and 8.7 times the Sun's mass.
The stellar classification of this star is B2Vne, which presents as a B-type main-sequence star. N. Houk in 1979 found a class of B2 IVne, with the luminosity class of IV suggesting that this may be a subgiant star that has exhausted the hydrogen at its core and begun to evolve away from the main sequence. Detailed study of the spectrum suggests that the disparity is due to gravity darkening which makes the subgiant spectrum appear similar to a main-sequence star. The star is spinning rapidly, with the resulting Doppler effect giving its spectrum broad absorption lines as indicated by the 'n'. The suffix 'e' means this is a classical Be star, which is a type of hot star that has not yet evolved into a supergiant and is surrounded by circumstellar gas. The presence of this gas creates an excess emission of infrared, along with emission lines in the star's spectrum. Most of it is concentrated around the equator, forming a disk.
Some of the variation in this star may be explained by assuming it is a binary star system. This proposed secondary star would need to have about 4–7 times the Sun's mass and be orbiting with a period of at least 4.6 years at a minimum separation of 6.9 Astronomical Units. δ Centauri shares a common proper motion with the nearby stars HD 105382 and HD 105383, so they may form a small cluster or perhaps a triple star system. It is a proper motion member of the Lower Centaurus–Crux sub-group in the Scorpius–Centaurus OB association, the nearest such of association of co-moving massive stars to the Sun.
Etymology
In Chinese, (), meaning Horse's Tail, refers to an asterism consisting of δ Centauri, G Centauri and ρ Centauri. Consequently, δ Centauri itself is known as (, .). From this Chinese name, the name Ma Wei appeared.
The people of Aranda and Luritja tribe around Hermannsburg, Central Australia, named Iritjinga, "The Eagle-hawk", a quadrangular arrangement comprising this star, γ Cen (Muhlifain), γ Cru (Gacrux), and δ Cru (Imai).
See also
Traditional Chinese star names
References
B-type main-sequence stars
B-type subgiants
Be stars
Gamma Cassiopeiae variable stars
Lower Centaurus Crux
Centaurus
Centauri, Delta
Durchmusterung objects
105435
059196
4621 | Delta Centauri | [
"Astronomy"
] | 746 | [
"Centaurus",
"Constellations"
] |
3,117,389 | https://en.wikipedia.org/wiki/Omicron%20Canis%20Majoris | The Bayer designation Omicron Canis Majoris (ο CMa / ο Canis Majoris) is shared by two stars, in the constellation Canis Major:
ο1 Canis Majoris
ο2 Canis Majoris
They are separated by 2.06° on the sky.
ο1 Canis Majoris was member of asterism 軍市 (Jūn Shì), Market for Soldiers, Well mansion. ο2 Canis Majoris was not any member of asterism.
References
Canis Major
Canis Majoris, Omicron | Omicron Canis Majoris | [
"Astronomy"
] | 113 | [
"Canis Major",
"Constellations"
] |
3,117,438 | https://en.wikipedia.org/wiki/Combined%20gas%20and%20gas | Combined gas turbine and gas turbine (COGAG) is a type of propulsion system for ships using two gas turbines connected to a single propeller shaft. A gearbox and clutches allow either of the turbines to drive the shaft or both of them combined. Marine usage of COGAG systems are similar to those found ashore.
Description
A COGAG system consists of two gas turbines, each connected to a reduction gearbox. These are each attached to a coupling with both connected to larger gearbox and then to the ship's propeller.
Advantages and disadvantages
Advantages of the system include a large degree of automation along with quick startup time, they are easier to silence and protect from shock. Compared to combined diesel and gas (CODAG) or combined diesel or gas (CODOG), COGAG systems have a smaller footprint but a much lower fuel efficiency at cruise speed and for CODAG systems it is also somewhat lower for high speed dashes. Issues with COGAG systems include their complexity and gearbox issues and high fuel use.
List of COGAG ships
guided-missile destroyer (Indian Navy)
(aircraft carrier) (Indian Navy)
Type 22 frigate (Batch 3) (Royal Navy)
(Royal Navy)
(Italian Navy)
(Japan Maritime Self-Defense Force), and subsequent destroyer classes
(Japan Maritime Self-Defense Force), helicopter carrier
(Japan Maritime Self-Defense Force), helicopter carrier
Type 055 destroyer (People's Liberation Army Navy)
(Russian Navy)
(Republic of Korea Navy)
(Royal Norwegian Navy)
(United States Navy)
(United States Navy)
Citations
References
Marine propulsion | Combined gas and gas | [
"Engineering"
] | 323 | [
"Marine propulsion",
"Marine engineering"
] |
3,117,447 | https://en.wikipedia.org/wiki/Eta%20Leonis | Eta Leonis (η Leo, η Leonis) is a third-magnitude blue supergiant star in the constellation Leo, about away.
Properties
Eta Leonis is a blue supergiant with the stellar classification A0Ib. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. Though its apparent magnitude is 3.5, making it a relatively dim star to the naked eye, it is nearly 20,000 times more luminous than the Sun, with an absolute magnitude of -5.60. The Hipparcos astrometric data has estimated the distance of Eta Leonis to be roughly 390 parsecs from Earth, or 1,270 light years away. It is believed to be in a blue loop phase.
Eta Leonis is apparently a multiple star system, but the number of components and their separation is uncertain.
References
External links
Jim Kaler's Stars: Eta Leonis
Leo (constellation)
Leonis, Eta
A-type supergiants
BD+17 2171
Leonis, 30
3975
87737
049583 | Eta Leonis | [
"Astronomy"
] | 227 | [
"Leo (constellation)",
"Constellations"
] |
3,117,475 | https://en.wikipedia.org/wiki/Combined%20diesel%20and%20diesel | Combined diesel and diesel (CODAD) is a propulsion system for ships using two diesel engines to power a single propeller shaft.
System
A gearbox and clutches enable either of the engines or both of them together to drive the shaft. Two advantages over simply using a single, larger diesel engine of the same total power output are that (1) diesel engines have somewhat better specific fuel consumption at 75% to 85% max output than they do at only 50% output, and (2) there is a weight and size advantage to using two higher-speed engines compared to a single lower-speed engine, even with the slightly larger gearbox system.
CODAD vessels
Passenger and Car Ferry Ships
M/F Povl Anker
Containerships
MV ACX Crystal
Coast Guard Offshore General-Purpose Cutters
Iwami-class patrol vessel
Shiretoko-class patrol vessel
Tanjung Datu-class patrol vessel
Coast Guard Offshore Security Patrol Cutters
Mizuho-class patrol vessel
Ojika-class patrol vessel
Coast Guard Multi-mission Cutters
Kunigami-class patrol vessel
Teresa Magbanua-class patrol vessel
Coast Guard Interceptor Cutters
Aso-class patrol vessel
Hateruma-class patrol vessel
Hida-class patrol vessel
Anping-class cutter
Tsurugi-class patrol vessel
Coast Guard Security Cutters
Heritage-class cutter
Mizuho (PLH-41)
Shikishima-class patrol vessel
Patrol Corvettes / Navy OPVs
Guaicamacuto-class patrol boat
Kedah-class offshore patrol vessel
Corvettes
Bung Karno-class corvette
Bung Tomo-class corvette
Diponegoro-class corvette
Doha-class corvette
Jacinto-class corvette
Kasturi-class corvette
Laksamana-class corvette
Parchim-class corvette
Steregushchiy-class corvette
Tuo Chiang-class corvette
Type 056 corvette
Frigates
Formidable-class frigate
Frégates de taille intermédiaire
Jose Rizal-class frigate
La Fayette-class frigate
Lekiu-class frigate
Maharaja Lela-class frigate
Miguel Malvar-class frigate
RN Type-31 Inspiration-class
Tamandaré-class frigate
Type 054A frigate
LSDs (landing ships, dock)
Whidbey Island-class dock landing ship
LPDs (landing platforms, dock)
Endurance-class landing platform dock
Galicia-class landing platform dock
Makassar-class landing platform dock
Tarlac-class landing platform dock
Amphibious Flat-topped Ships
Dokdo-class amphibious assault ship
Ōsumi-class dock landing ship
FACs (fast attack-craft)
Clurit-class fast attack craft
Cyclone-class coastal patrol ship
Sampari-class fast attack craft
Cruise Ships
MV Piano Land (formerly MV Oriana)
References
Marine propulsion
Marine diesel engines | Combined diesel and diesel | [
"Engineering"
] | 562 | [
"Marine propulsion",
"Marine engineering"
] |
3,117,495 | https://en.wikipedia.org/wiki/Upsilon%20Carinae | Upsilon Carinae, Latinized from υ Carinae, is a double star in the southern constellation of Carina. It is part of the Diamond Cross asterism in southern Carina. The Upsilon Carinae system has a combined apparent magnitude of +2.97 and is approximately 1,400 light years (440 parsecs) from Earth.
In Chinese, (), meaning Sea Rock, refers to an asterism consisting of υ Carinae, ε Carinae, ι Carinae, HD 83183 and HD 84810. Consequently, υ Carinae itself is known as (, .)
The primary component, υ Carinae A, has a stellar classification of A8 Ib, making it a supergiant star that has exhausted the hydrogen at its core and evolved away from its brief main sequence lifetime as an B-type star. With an apparent magnitude of +3.08, it has an effective temperature of about 7,500 K, giving it a white hue. The companion, υ Carinae B, is a giant star with a classification of B7 III, although Mandrini and Niemela (1986) suggested it may be a subgiant star with a classification of B4–5 IV. The outer envelope of this star has an effective temperature of around 23,000 K, resulting in the blue-white hue of a B-type star.
The two stars have an angular separation of 5.030 arcseconds. As a binary star system, they would have an estimated orbital period of at least 19,500 years and a present-day separation of around 2,000 Astronomical Units. This system is roughly 12 million years old.
In the next 7500 years, the south Celestial pole will pass close to these stars and Iota Carinae (8100 CE).
References
External links
Southern Sky Photos
Carina (constellation)
Carinae, Upsilon
B-type subgiants
Double stars
A-type supergiants
048002
085123
3890
PD-64 01084 | Upsilon Carinae | [
"Astronomy"
] | 422 | [
"Carina (constellation)",
"Constellations"
] |
3,117,746 | https://en.wikipedia.org/wiki/Timing%20mark | A timing mark is an indicator used for setting the timing of the ignition system of an engine, typically found on the crankshaft pulley (as pictured) or the flywheel. These have the largest radius rotating at crankshaft speed and therefore are the place where marks at one degree intervals will be farthest apart.
On older engines it is common to set the ignition timing using a timing light, which flashes in time with the ignition system (and hence engine rotation). Shining the light on the timing marks makes them appear stationary due to the stroboscopic effect. The ignition timing can then be adjusted to fire at the correct point in the engine's rotation, typically a few degrees before top dead centre and advancing with increasing engine speed. The timing can be adjusted by loosening and slightly rotating the distributor in its seat.
Modern engines usually use a crank sensor directly connected to the engine management system.
The term can also be used to describe the tick marks along the length of an optical mark recognition sheet, used to confirm the location of the sheet as it passes through the reader. See, for example, U.S. Patent 3,218,439 (filed 1964, granted 1965), which refers to a timing track down the left side of the form, and U.S. Patent 3,267,258 (filed 1963, granted 1966), which refers to a column of timing marks on the right side of the form.
The term can also be used to describe the timing patterns used in some barcodes, such as PostBar, Data Matrix, Aztec Code, etc.
References
External links
Ignition systems
Synchronization
Engine technology | Timing mark | [
"Technology",
"Engineering"
] | 333 | [
"Engine technology",
"Telecommunications engineering",
"Synchronization",
"Engines"
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3,117,887 | https://en.wikipedia.org/wiki/Grassmann%20number | In mathematical physics, a Grassmann number, named after Hermann Grassmann (also called an anticommuting number or supernumber), is an element of the exterior algebra of a complex vector space. The special case of a 1-dimensional algebra is known as a dual number. Grassmann numbers saw an early use in physics to express a path integral representation for fermionic fields, although they are now widely used as a foundation for superspace, on which supersymmetry is constructed.
Informal discussion
Grassmann numbers are generated by anti-commuting elements or objects. The idea of anti-commuting objects arises in multiple areas of mathematics: they are typically seen in differential geometry, where the differential forms are anti-commuting. Differential forms are normally defined in terms of derivatives on a manifold; however, one can contemplate the situation where one "forgets" or "ignores" the existence of any underlying manifold, and "forgets" or "ignores" that the forms were defined as derivatives, and instead, simply contemplate a situation where one has objects that anti-commute, and have no other pre-defined or presupposed properties. Such objects form an algebra, and specifically the Grassmann algebra or exterior algebra.
The Grassmann numbers are elements of that algebra. The appellation of "number" is justified by the fact that they behave not unlike "ordinary" numbers: they can be added, multiplied and divided: they behave almost like a field. More can be done: one can consider polynomials of Grassmann numbers, leading to the idea of holomorphic functions. One can take derivatives of such functions, and then consider the anti-derivatives as well. Each of these ideas can be carefully defined, and correspond reasonably well to the equivalent concepts from ordinary mathematics. The analogy does not stop there: one has an entire branch of supermathematics, where the analog of Euclidean space is superspace, the analog of a manifold is a supermanifold, the analog of a Lie algebra is a Lie superalgebra and so on. The Grassmann numbers are the underlying construct that make this all possible.
Of course, one could pursue a similar program for any other field, or even ring, and this is indeed widely and commonly done in mathematics. However, supermathematics takes on a special significance in physics, because the anti-commuting behavior can be strongly identified with the quantum-mechanical behavior of fermions: the anti-commutation is that of the Pauli exclusion principle. Thus, the study of Grassmann numbers, and of supermathematics, in general, is strongly driven by their utility in physics.
Specifically, in quantum field theory, or more narrowly, second quantization, one works with ladder operators that create multi-particle quantum states. The ladder operators for fermions create field quanta that must necessarily have anti-symmetric wave functions, as this is forced by the Pauli exclusion principle. In this situation, a Grassmann number corresponds immediately and directly to a wave function that contains some (typically indeterminate) number of fermions.
When the number of fermions is fixed and finite, an explicit relationship between anticommutation relations and spinors is given by means of the spin group. This group can be defined as the subset of unit-length vectors in the Clifford algebra, and naturally factorizes into anti-commuting Weyl spinors. Both the anti-commutation and the expression as spinors arises in a natural fashion for the spin group. In essence, the Grassmann numbers can be thought of as discarding the relationships arising from spin, and keeping only the relationships due to anti-commutation.
General description and properties
Grassmann numbers are individual elements or points of the exterior algebra generated by a set of Grassmann variables or Grassmann directions or supercharges , with possibly being infinite. The usage of the term "Grassmann variables" is historic; they are not variables, per se; they are better understood as the basis elements of a unital algebra. The terminology comes from the fact that a primary use is to define integrals, and that the variable of integration is Grassmann-valued, and thus, by abuse of language, is called a Grassmann variable. Similarly, the notion of direction comes from the notion of superspace, where ordinary Euclidean space is extended with additional Grassmann-valued "directions". The appellation of charge comes from the notion of charges in physics, which correspond to the generators of physical symmetries (via Noether's theorem). The perceived symmetry is that multiplication by a single Grassmann variable swaps the grading between fermions and bosons; this is discussed in greater detail below.
The Grassmann variables are the basis vectors of a vector space (of dimension ). They form an algebra over a field, with the field usually being taken to be the complex numbers, although one could contemplate other fields, such as the reals. The algebra is a unital algebra, and the generators are anti-commuting:
Since the are elements of a vector space over the complex numbers, they, by definition, commute with complex numbers. That is, for complex , one has
The squares of the generators vanish:
since
In other words, a Grassmann variable is a non-zero square-root of zero.
Formal definition
Formally, let be an -dimensional complex vector space with basis . The Grassmann algebra whose Grassmann variables are is defined to be the exterior algebra of , namely
where is the exterior product and is the direct sum. The individual elements of this algebra are then called Grassmann numbers. It is standard to omit the wedge symbol when writing a Grassmann number once the definition is established. A general Grassmann number can be written as
where are strictly increasing -tuples with , and the are complex, completely antisymmetric tensors of rank . Again, the , and the (subject to ), and larger finite products, can be seen here to be playing the role of a basis vectors of subspaces of .
The Grassmann algebra generated by linearly independent Grassmann variables has dimension ; this follows from the binomial theorem applied to the above sum, and the fact that the -fold product of variables must vanish, by the anti-commutation relations above. The dimension of is given by choose , the binomial coefficient. The special case of is called a dual number, and was introduced by William Clifford in 1873.
In case is infinite-dimensional, the above series does not terminate and one defines
The general element is now
where is sometimes referred to as the body and as the soul of the supernumber .
Properties
In the finite-dimensional case (using the same terminology) the soul is nilpotent, i.e.
but this is not necessarily so in the infinite-dimensional case.
If is finite-dimensional, then
and if is infinite-dimensional
Finite vs. countable sets of generators
Two distinct kinds of supernumbers commonly appear in the literature: those with a finite number of generators, typically = 1, 2, 3 or 4, and those with a countably-infinite number of generators. These two situations are not as unrelated as they may seem at first. First, in the definition of a supermanifold, one variant uses a countably-infinite number of generators, but then employs a topology that effectively reduces the dimension to a small finite number.
In the other case, one may start with a finite number of generators, but in the course of second quantization, a need for an infinite number of generators arises: one each for every possible momentum that a fermion might carry.
Involution, choice of field
The complex numbers are usually chosen as the field for the definition of the Grassmann numbers, as opposed to the real numbers, as this avoids some strange behaviors when a conjugation or involution is introduced. It is common to introduce an operator * on the Grassmann numbers such that:
when is a generator, and such that
One may then consider Grassmann numbers z for which , and term these (super) real, while those that obey are termed (super) imaginary. These definitions carry through just fine, even if the Grassmann numbers use the real numbers as the base field; however, in such a case, many coefficients are forced to vanish if the number of generators is less than 4. Thus, by convention, the Grassmann numbers are usually defined over the complex numbers.
Other conventions are possible; the above is sometimes referred to as the DeWitt convention; Rogers employs for the involution. In this convention, the real supernumbers always have real coefficients; whereas in the DeWitt convention, the real supernumbers may have both real and imaginary coefficients. Despite this, it is usually easiest to work with the DeWitt convention.
Analysis
Products of an odd number of Grassmann variables anti-commute with each other; such a product is often called an a-number. Products of an even number of Grassmann variables commute (with all Grassman numbers); they are often called c-numbers. By abuse of terminology, an a-number is sometimes called an anticommuting c-number. This decomposition into even and odd subspaces provides a grading on the algebra; thus Grassmann algebras are the prototypical examples of supercommutative algebras. Note that the c-numbers form a subalgebra of , but the a-numbers do not (they are a subspace, not a subalgebra).
The definition of Grassmann numbers allows mathematical analysis to be performed, in analogy to analysis on complex numbers. That is, one may define superholomorphic functions, define derivatives, as well as defining integrals. Some of the basic concepts are developed in greater detail in the article on dual numbers.
As a general rule, it is usually easier to define the super-symmetric analogs of ordinary mathematical entities by working with Grassmann numbers with an infinite number of generators: most definitions become straightforward, and can be taken over from the corresponding bosonic definitions. For example, a single Grassmann number can be thought of as generating a one-dimensional space. A vector space, the -dimensional superspace, then appears as the -fold Cartesian product of these one-dimensional It can be shown that this is essentially equivalent to an algebra with generators, but this requires work.
Spinor space
The spinor space is defined as the Grassmann or exterior algebra of the space of Weyl spinors (and anti-spinors ), such that the wave functions of n fermions belong in .
Integration
Integrals over Grassmann numbers are known as Berezin integrals (sometimes called Grassmann integrals). In order to reproduce the path integral for a Fermi field, the definition of Grassmann integration needs to have the following properties:
linearity
partial integration formula
Moreover, the Taylor expansion of any function terminates after two terms because , and quantum field theory additionally require invariance under the shift of integration variables such that
The only linear function satisfying this condition is a constant (conventionally 1) times , so Berezin defined
This results in the following rules for the integration of a Grassmann quantity:
Thus we conclude that the operations of integration and differentiation of a Grassmann number are identical.
In the path integral formulation of quantum field theory the following Gaussian integral of Grassmann quantities is needed for fermionic anticommuting fields, with A being an N × N matrix:
.
Conventions and complex integration
An ambiguity arises when integrating over multiple Grassmann numbers. The convention that performs the innermost integral first yields
Some authors also define complex conjugation similar to Hermitian conjugation of operators,
With the additional convention
we can treat and as independent Grassmann numbers, and adopt
Thus a Gaussian integral evaluates to
and an extra factor of effectively introduces a factor of , just like an ordinary Gaussian,
After proving unitarity, we can evaluate a general Gaussian integral involving a Hermitian matrix with eigenvalues ,
Matrix representations
Grassmann numbers can be represented by matrices. Consider, for example, the Grassmann algebra generated by two Grassmann numbers and . These Grassmann numbers can be represented by 4×4 matrices:
In general, a Grassmann algebra on n generators can be represented by 2n × 2n square matrices. Physically, these matrices can be thought of as raising operators acting on a Hilbert space of n identical fermions in the occupation number basis. Since the occupation number for each fermion is 0 or 1, there are 2n possible basis states. Mathematically, these matrices can be interpreted as the linear operators corresponding to left exterior multiplication on the Grassmann algebra itself.
Generalisations
There are some generalisations to Grassmann numbers. These require rules in terms of N variables such that:
where the indices are summed over all permutations so that as a consequence:
for some N > 2. These are useful for calculating hyperdeterminants of N-tensors where N > 2 and also for calculating discriminants of polynomials for powers larger than 2. There is also the limiting case as N tends to infinity in which case one can define analytic functions on the numbers. For example, in the case with N = 3 a single Grassmann number can be represented by the matrix:
so that . For two Grassmann numbers the matrix would be of size 10×10.
For example, the rules for N = 3 with two Grassmann variables imply:
so that it can be shown that
and so
which gives a definition for the hyperdeterminant of a 2×2×2 tensor as
See also
Grassmannian
Hermann Grassmann (linguist and mathematician)
Superspace
Exterior algebra
Notes
References
Hypercomplex numbers
Supersymmetry
Quantum field theory | Grassmann number | [
"Physics",
"Mathematics"
] | 2,846 | [
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"Mathematical structures",
"Unsolved problems in physics",
"Quantum mechanics",
"Mathematical objects",
"Numbers",
"Algebraic structures",
"Physics beyond the Standard Model",
"Hypercomplex numbers",
"Supersymmetry",
"Symmetry"
] |
3,117,974 | https://en.wikipedia.org/wiki/Microsoft%20Transaction%20Server | Microsoft Transaction Server (MTS) was software that provided services to Component Object Model (COM) software components, to make it easier to create large distributed applications. The major services provided by MTS were automated transaction management, instance management (or just-in-time activation) and role-based security. MTS is considered to be the first major software to implement aspect-oriented programming.
MTS was first offered in the Windows NT 4.0 Option Pack. In Windows 2000, MTS was enhanced and better integrated with the operating system and COM, and was renamed COM+. COM+ added object pooling, loosely-coupled events and user-defined simple transactions (compensating resource managers) to the features of MTS.
COM+ is still provided with Windows Server 2003 and Windows Server 2008, and the Microsoft .NET Framework provides a wrapper for COM+ in the EnterpriseServices namespace. The Windows Communication Foundation (WCF) provides a way of calling COM+ applications with web services. However, COM+ is based on COM, and Microsoft's strategic software architecture is now web services and .NET, not COM. There are pure .NET-based alternatives for many of the features provided by COM+, and in the long term it is likely COM+ will be phased out.
Architecture
A basic MTS architecture comprises:
the MTS Executive (mtxex.dll)
the Factory Wrappers and Context Wrappers for each component
the MTS Server Component
MTS clients
auxiliary systems like:
COM runtime services
the Service Control Manager (SCM)
the Microsoft Distributed Transaction Coordinator (MS-DTC)
the Microsoft Message Queue (MSMQ)
the COM-Transaction Integrator (COM-TI)
etc.
COM components that run under the control of the MTS Executive are called MTS components. In COM+, they are referred to as COM+ Applications. MTS components are in-process DLLs. MTS components are deployed and run in the MTS Executive which manages them. As with other COM components, an object implementing the IClassFactory interface serves as a Factory Object to create new instances of these components.
MTS inserts a Factory Wrapper Object and an Object Wrapper between the actual MTS object and its client. This interposing of wrappers is called interception. Whenever the client makes a call to the MTS component, the wrappers (Factory and Object) intercept the call and inject their own instance-management algorithm called the Just-In-Time Activation (JITA) into the call. The wrapper then makes this call on the actual MTS component. Interception was considered difficult at the time due to a lack of extensible metadata.
In addition, based on the information from the component's deployment properties, transaction logic and security checks also take place in these wrapper objects.
For every MTS-hosted object, there also exists a Context Object, which implements the IObjectContext interface. The Context Object maintains specific information about that object, such as its transactional information, security information and deployment information. Methods in the MTS component call into the Context Object through its IObjectContext interface.
MTS does not create the actual middle-tier MTS object until the call from a client reaches the container. Since the object is not running all the time, it does not use up a lot of system resources (even though an object wrapper and skeleton for the object do persist).
As soon as the call comes in from the client, the MTS wrapper process activates its Instance Management algorithm called JITA. The actual MTS object is created "just in time" to service the request from the wrapper. And when the request is serviced and the reply is sent back to the client, the component either calls SetComplete()/SetAbort(), or its transaction ends, or the client calls Release() on the reference to the object, and the actual MTS object is destroyed. In short, MTS uses a stateless component model.
Generally, when a client requests services from a typical MTS component, the following sequence occurs on the server :
acquire a database connection
read the component's state from either the Shared Property Manager or from an already existing object or from the client
perform the business logic
write the component's changed state, if any, back to the database
close and release the database connection
vote on the result of the transaction. MTS components do not directly commit transactions, rather they communicate their success or failure to MTS.
It is thus possible to implement high-latency resources as asynchronous resource pools, which should take advantage of the stateless JIT activation afforded by the middleware server.
References
External links and references
Quick Tour of Microsoft Transaction Server
Windows components
Windows communication and services
Inter-process communication
Microsoft application programming interfaces
Component-based software engineering
Transaction processing | Microsoft Transaction Server | [
"Technology"
] | 1,002 | [
"Component-based software engineering",
"Components"
] |
3,118,117 | https://en.wikipedia.org/wiki/Adjunction%20formula | In mathematics, especially in algebraic geometry and the theory of complex manifolds, the adjunction formula relates the canonical bundle of a variety and a hypersurface inside that variety. It is often used to deduce facts about varieties embedded in well-behaved spaces such as projective space or to prove theorems by induction.
Adjunction for smooth varieties
Formula for a smooth subvariety
Let X be a smooth algebraic variety or smooth complex manifold and Y be a smooth subvariety of X. Denote the inclusion map by i and the ideal sheaf of Y in X by . The conormal exact sequence for i is
where Ω denotes a cotangent bundle. The determinant of this exact sequence is a natural isomorphism
where denotes the dual of a line bundle.
The particular case of a smooth divisor
Suppose that D is a smooth divisor on X. Its normal bundle extends to a line bundle on X, and the ideal sheaf of D corresponds to its dual . The conormal bundle is , which, combined with the formula above, gives
In terms of canonical classes, this says that
Both of these two formulas are called the adjunction formula.
Examples
Degree d hypersurfaces
Given a smooth degree hypersurface we can compute its canonical and anti-canonical bundles using the adjunction formula. This reads aswhich is isomorphic to .
Complete intersections
For a smooth complete intersection of degrees , the conormal bundle is isomorphic to , so the determinant bundle is and its dual is , showingThis generalizes in the same fashion for all complete intersections.
Curves in a quadric surface
embeds into as a quadric surface given by the vanishing locus of a quadratic polynomial coming from a non-singular symmetric matrix. We can then restrict our attention to curves on . We can compute the cotangent bundle of using the direct sum of the cotangent bundles on each , so it is . Then, the canonical sheaf is given by , which can be found using the decomposition of wedges of direct sums of vector bundles. Then, using the adjunction formula, a curve defined by the vanishing locus of a section , can be computed as
Poincaré residue
The restriction map is called the Poincaré residue. Suppose that X is a complex manifold. Then on sections, the Poincaré residue can be expressed as follows. Fix an open set U on which D is given by the vanishing of a function f. Any section over U of can be written as s/f, where s is a holomorphic function on U. Let η be a section over U of ωX. The Poincaré residue is the map
that is, it is formed by applying the vector field ∂/∂f to the volume form η, then multiplying by the holomorphic function s. If U admits local coordinates z1, ..., zn such that for some i, ∂f/∂zi ≠ 0, then this can also be expressed as
Another way of viewing Poincaré residue first reinterprets the adjunction formula as an isomorphism
On an open set U as before, a section of is the product of a holomorphic function s with the form . The Poincaré residue is the map that takes the wedge product of a section of ωD and a section of .
Inversion of adjunction
The adjunction formula is false when the conormal exact sequence is not a short exact sequence. However, it is possible to use this failure to relate the singularities of X with the singularities of D. Theorems of this type are called inversion of adjunction. They are an important tool in modern birational geometry.
The Canonical Divisor of a Plane Curve
Let be a smooth plane curve cut out by a degree homogeneous polynomial . We claim that the canonical divisor is where is the hyperplane divisor.
First work in the affine chart . The equation becomes where and .
We will explicitly compute the divisor of the differential
At any point either so is a local parameter or
so is a local parameter.
In both cases the order of vanishing of at the point is zero. Thus all contributions to the divisor are at the line at infinity, .
Now look on the line . Assume that so it suffices to look in the chart with coordinates and . The equation of the curve becomes
Hence
so
with order of vanishing . Hence which agrees with the adjunction formula.
Applications to curves
The genus-degree formula for plane curves can be deduced from the adjunction formula. Let C ⊂ P2 be a smooth plane curve of degree d and genus g. Let H be the class of a hyperplane in P2, that is, the class of a line. The canonical class of P2 is −3H. Consequently, the adjunction formula says that the restriction of to C equals the canonical class of C. This restriction is the same as the intersection product restricted to C, and so the degree of the canonical class of C is . By the Riemann–Roch theorem, g − 1 = (d−3)d − g + 1, which implies the formula
Similarly, if C is a smooth curve on the quadric surface P1×P1 with bidegree (d1,d2) (meaning d1,d2 are its intersection degrees with a fiber of each projection to P1), since the canonical class of P1×P1 has bidegree (−2,−2), the adjunction formula shows that the canonical class of C is the intersection product of divisors of bidegrees (d1,d2) and (d1−2,d2−2). The intersection form on P1×P1 is by definition of the bidegree and by bilinearity, so applying Riemann–Roch gives or
The genus of a curve C which is the complete intersection of two surfaces D and E in P3 can also be computed using the adjunction formula. Suppose that d and e are the degrees of D and E, respectively. Applying the adjunction formula to D shows that its canonical divisor is , which is the intersection product of and D. Doing this again with E, which is possible because C is a complete intersection, shows that the canonical divisor C is the product , that is, it has degree . By the Riemann–Roch theorem, this implies that the genus of C is
More generally, if C is the complete intersection of hypersurfaces of degrees in Pn, then an inductive computation shows that the canonical class of C is . The Riemann–Roch theorem implies that the genus of this curve is
In low dimensional topology
Let S be a complex surface (in particular a 4-dimensional manifold) and let be a smooth (non-singular) connected complex curve. Then
where is the genus of C, denotes the self-intersections and denotes the Kronecker pairing .
See also
Logarithmic form
Poincare residue
Thom conjecture
References
Intersection theory 2nd edition, William Fulton, Springer, , Example 3.2.12.
Principles of algebraic geometry, Griffiths and Harris, Wiley classics library, pp 146–147.
Algebraic geometry, Robin Hartshorne, Springer GTM 52, , Proposition II.8.20.
Algebraic geometry | Adjunction formula | [
"Mathematics"
] | 1,503 | [
"Fields of abstract algebra",
"Algebraic geometry"
] |
3,118,228 | https://en.wikipedia.org/wiki/Canadian%20Society%20for%20Civil%20Engineering | The Canadian Society for Civil Engineering (CSCE) () was founded in 1887 as the Canadian Society of Civil Engineers, renamed in 1918 as the Engineering Institute of Canada (EIC), and re-established in June 1972 as a member society of the EIC under the slightly different but current name. It promotes advances in the field of civil engineering including geotechnical engineering, structural engineering, hydrotechnical engineering, environmental engineering, transportation engineering and surveying and geomatics engineering. Members who are professional civil engineers are usually categorized and may use the post nominals as associates (AMCSCE), members (MCSCE) or fellows (FCSCE). The grade of "Fellow" is achieved through election by one's peers within the CSCE.
There are also student chapters of the Canadian Society for Civil Engineering at many universities throughout the country including the University of Toronto, University of Waterloo, McGill University and the University of British Columbia.
In the year 2019, the CSCE named its best paper award in construction after Osama Moselhi. Moselhi Best Paper Award is offered every two years in the construction specialty conference.
References
External links
Professional associations based in Canada
Civil engineering professional associations | Canadian Society for Civil Engineering | [
"Engineering"
] | 245 | [
"Civil engineering professional associations",
"Civil engineering organizations"
] |
3,118,411 | https://en.wikipedia.org/wiki/Rotation%20system | In combinatorial mathematics, rotation systems (also called combinatorial embeddings or combinatorial maps) encode embeddings of graphs onto orientable surfaces by describing the circular ordering of a graph's edges around each vertex.
A more formal definition of a rotation system involves pairs of permutations; such a pair is sufficient to determine a multigraph, a surface, and a 2-cell embedding of the multigraph onto the surface.
Every rotation scheme defines a unique 2-cell embedding of a connected multigraph on a closed oriented surface (up to orientation-preserving topological equivalence). Conversely, any embedding of a connected multigraph G on an oriented closed surface defines a unique rotation system having G as its underlying multigraph. This fundamental equivalence between rotation systems and 2-cell-embeddings was first settled in a dual form by Lothar Heffter in the 1890s and extensively used by Ringel during the 1950s. Independently, Edmonds gave the primal form of the theorem and the details of his study have been popularized by Youngs. The generalization to multigraphs was presented by Gross and Alpert.
Rotation systems are related to, but not the same as, the rotation maps used by Reingold et al. (2002) to define the zig-zag product of graphs. A rotation system specifies a circular ordering of the edges around each vertex, while a rotation map specifies a (non-circular) permutation of the edges at each vertex. In addition, rotation systems can be defined for any graph, while as Reingold et al. define them rotation maps are restricted to regular graphs.
Formal definition
Formally, a rotation system is defined as a pair (σ, θ) where σ and θ are permutations acting on the same ground set B, θ is a fixed-point-free involution, and the group <σ, θ> generated by σ and θ acts transitively on B.
To derive a rotation system from a 2-cell embedding of a connected multigraph G on an oriented surface, let B consist of the darts (or flags, or half-edges) of G; that is, for each edge of G we form two elements of B, one for each endpoint of the edge. Even when an edge has the same vertex as both of its endpoints, we create two darts for that edge. We let θ(b) be the other dart formed from the same edge as b; this is clearly an involution with no fixed points. We let σ(b) be the dart in the clockwise position from b in the cyclic order of edges incident to the same vertex, where "clockwise" is defined by the orientation of the surface.
If a multigraph is embedded on an orientable but not oriented surface, it generally corresponds to two rotation systems, one for each of the two orientations of the surface. These two rotation systems have the same involution θ, but the permutation σ for one rotation system is the inverse of the corresponding permutation for the other rotation system.
Recovering the embedding from the rotation system
To recover a multigraph from a rotation system, we form a vertex for each orbit of σ, and an edge for each orbit of θ. A vertex is incident with an edge if these two orbits have a nonempty intersection. Thus, the number of incidences per vertex is the size of the orbit, and the number of incidences per edge is exactly two. If a rotation system is derived from a 2-cell embedding of a connected multigraph G, the graph derived from the rotation system is isomorphic to G.
To embed the graph derived from a rotation system onto a surface, form a disk for each orbit of σθ, and glue two disks together along an edge e whenever the two darts corresponding to e belong to the two orbits corresponding to these disks. The result is a 2-cell embedding of the derived multigraph, the two-cells of which are the disks corresponding to the orbits of σθ. The surface of this embedding can be oriented in such a way that the clockwise ordering of the edges around each vertex is the same as the clockwise ordering given by σ.
Characterizing the surface of the embedding
According to the Euler formula we can deduce the genus g of the closed orientable surface defined by the rotation system (that is, the surface on which the underlying multigraph is 2-cell embedded). Notice that , and . We find that
where denotes the set of the orbits of permutation .
See also
Combinatorial map
Notes
References
.
Topological graph theory | Rotation system | [
"Mathematics"
] | 960 | [
"Mathematical relations",
"Topological graph theory",
"Topology",
"Graph theory"
] |
3,118,600 | https://en.wikipedia.org/wiki/Concept%20drift | In predictive analytics, data science, machine learning and related fields, concept drift or drift is an evolution of data that invalidates the data model. It happens when the statistical properties of the target variable, which the model is trying to predict, change over time in unforeseen ways. This causes problems because the predictions become less accurate as time passes. Drift detection and drift adaptation are of paramount importance in the fields that involve dynamically changing data and data models.
Predictive model decay
In machine learning and predictive analytics this drift phenomenon is called concept drift. In machine learning, a common element of a data model are the statistical properties, such as probability distribution of the actual data. If they deviate from the statistical properties of the training data set, then the learned predictions may become invalid, if the drift is not addressed.
Data configuration decay
Another important area is software engineering, where three types of data drift affecting data fidelity may be recognized. Changes in the software environment ("infrastructure drift") may invalidate software infrastructure configuration. "Structural drift" happens when the data schema changes, which may invalidate databases. "Semantic drift" is changes in the meaning of data while the structure does not change. In many cases this may happen in complicated applications when many independent developers introduce changes without proper awareness of the effects of their changes in other areas of the software system.
For many application systems, the nature of data on which they operate are subject to changes for various reasons, e.g., due to changes in business model, system updates, or switching the platform on which the system operates.
In the case of cloud computing, infrastructure drift that may affect the applications running on cloud may be caused by the updates of cloud software.
There are several types of detrimental effects of data drift on data fidelity. Data corrosion is passing the drifted data into the system undetected. Data loss happens when valid data are ignored due to non-conformance with the applied schema. Squandering is the phenomenon when new data fields are introduced upstream the data processing pipeline, but somewhere downstream there data fields are absent.
Inconsistent data
"Data drift" may refer to the phenomenon when database records fail to match the real-world data due to the changes in the latter over time. This is a common problem with databases involving people, such as customers, employees, citizens, residents, etc. Human data drift may be caused by unrecorded changes in personal data, such as place of residence or name, as well as due to errors during data input.
"Data drift" may also refer to inconsistency of data elements between several replicas of a database. The reasons can be difficult to identify. A simple drift detection is to run checksum regularly. However the remedy may be not so easy.
Examples
The behavior of the customers in an online shop may change over time. For example, if weekly merchandise sales are to be predicted, and a predictive model has been developed that works satisfactorily. The model may use inputs such as the amount of money spent on advertising, promotions being run, and other metrics that may affect sales. The model is likely to become less and less accurate over time – this is concept drift. In the merchandise sales application, one reason for concept drift may be seasonality, which means that shopping behavior changes seasonally. Perhaps there will be higher sales in the winter holiday season than during the summer, for example. Concept drift generally occurs when the covariates that comprise the data set begin to explain the variation of your target set less accurately — there may be some confounding variables that have emerged, and that one simply cannot account for, which renders the model accuracy to progressively decrease with time. Generally, it is advised to perform health checks as part of the post-production analysis and to re-train the model with new assumptions upon signs of concept drift.
Possible remedies
To prevent deterioration in prediction accuracy because of concept drift, reactive and tracking solutions can be adopted. Reactive solutions retrain the model in reaction to a triggering mechanism, such as a change-detection test, to explicitly detect concept drift as a change in the statistics of the data-generating process. When concept drift is detected, the current model is no longer up-to-date and must be replaced by a new one to restore prediction accuracy. A shortcoming of reactive approaches is that performance may decay until the change is detected. Tracking solutions seek to track the changes in the concept by continually updating the model. Methods for achieving this include online machine learning, frequent retraining on the most recently observed samples, and maintaining an ensemble of classifiers where one new classifier is trained on the most recent batch of examples and replaces the oldest classifier in the ensemble.
Contextual information, when available, can be used to better explain the causes of the concept drift: for instance, in the sales prediction application, concept drift might be compensated by adding information about the season to the model. By providing information about the time of the year, the rate of deterioration of your model is likely to decrease, but concept drift is unlikely to be eliminated altogether. This is because actual shopping behavior does not follow any static, finite model. New factors may arise at any time that influence shopping behavior, the influence of the known factors or their interactions may change.
Concept drift cannot be avoided for complex phenomena that are not governed by fixed laws of nature. All processes that arise from human activity, such as socioeconomic processes, and biological processes are likely to experience concept drift. Therefore, periodic retraining, also known as refreshing, of any model is necessary.
See also
Data stream mining
Data mining
Snyk, a company whose portfolio includes drift detection in software applications
Further reading
Many papers have been published describing algorithms for concept drift detection. Only reviews, surveys and overviews are here:
Reviews
External links
Software
Frouros: An open-source Python library for drift detection in machine learning systems.
NannyML: An open-source Python library for detecting univariate and multivariate distribution drift and estimating machine learning model performance without ground truth labels.
RapidMiner: Formerly Yet Another Learning Environment (YALE): free open-source software for knowledge discovery, data mining, and machine learning also featuring data stream mining, learning time-varying concepts, and tracking drifting concept. It is used in combination with its data stream mining plugin (formerly concept drift plugin).
EDDM (Early Drift Detection Method): free open-source implementation of drift detection methods in Weka.
MOA (Massive Online Analysis): free open-source software specific for mining data streams with concept drift. It contains a prequential evaluation method, the EDDM concept drift methods, a reader of ARFF real datasets, and artificial stream generators as SEA concepts, STAGGER, rotating hyperplane, random tree, and random radius based functions. MOA supports bi-directional interaction with Weka.
Datasets
Real
USP Data Stream Repository, 27 real-world stream datasets with concept drift compiled by Souza et al. (2020). Access
Airline, approximately 116 million flight arrival and departure records (cleaned and sorted) compiled by E. Ikonomovska. Reference: Data Expo 2009 Competition . Access
Chess.com (online games) and Luxembourg (social survey) datasets compiled by I. Zliobaite. Access
ECUE spam 2 datasets each consisting of more than 10,000 emails collected over a period of approximately 2 years by an individual. Access from S.J.Delany webpage
Elec2, electricity demand, 2 classes, 45,312 instances. Reference: M. Harries, Splice-2 comparative evaluation: Electricity pricing, Technical report, The University of South Wales, 1999. Access from J.Gama webpage. Comment on applicability.
PAKDD'09 competition data represents the credit evaluation task. It is collected over a five-year period. Unfortunately, the true labels are released only for the first part of the data. Access
Sensor stream and Power supply stream datasets are available from X. Zhu's Stream Data Mining Repository. Access
SMEAR is a benchmark data stream with a lot of missing values. Environment observation data over 7 years. Predict cloudiness. Access
Text mining, a collection of text mining datasets with concept drift, maintained by I. Katakis. Access
Gas Sensor Array Drift Dataset, a collection of 13,910 measurements from 16 chemical sensors utilized for drift compensation in a discrimination task of 6 gases at various levels of concentrations. Access
Other
KDD'99 competition data contains simulated intrusions in a military network environment. It is often used as a benchmark to evaluate handling concept drift. Access
Synthetic
Extreme verification latency benchmark Access from Nonstationary Environments – Archive.
Sine, Line, Plane, Circle and Boolean Data Sets Access from L.Minku webpage.
SEA concepts Access from J.Gama webpage.
STAGGER
Mixed
Data generation frameworks
Download from L.Minku webpage.
Code
Projects
INFER: Computational Intelligence Platform for Evolving and Robust Predictive Systems (2010–2014), Bournemouth University (UK), Evonik Industries (Germany), Research and Engineering Centre (Poland)
HaCDAIS: Handling Concept Drift in Adaptive Information Systems (2008–2012), Eindhoven University of Technology (the Netherlands)
KDUS: Knowledge Discovery from Ubiquitous Streams, INESC Porto and Laboratory of Artificial Intelligence and Decision Support (Portugal)
ADEPT: Adaptive Dynamic Ensemble Prediction Techniques, University of Manchester (UK), University of Bristol (UK)
ALADDIN: autonomous learning agents for decentralised data and information networks (2005–2010)
GAENARI: C++ incremental decision tree algorithm. it minimize concept drifting damage. (2022)
Benchmarks
NAB: The Numenta Anomaly Benchmark, benchmark for evaluating algorithms for anomaly detection in streaming, real-time applications. (2014–2018)
Meetings
2014
[] Special Session on "Concept Drift, Domain Adaptation & Learning in Dynamic Environments" @IEEE IJCNN 2014
2013
RealStream Real-World Challenges for Data Stream Mining Workshop-Discussion at the ECML PKDD 2013, Prague, Czech Republic.
LEAPS 2013 The 1st International Workshop on Learning stratEgies and dAta Processing in nonStationary environments
2011
LEE 2011 Special Session on Learning in evolving environments and its application on real-world problems at ICMLA'11
HaCDAIS 2011 The 2nd International Workshop on Handling Concept Drift in Adaptive Information Systems
ICAIS 2011 Track on Incremental Learning
IJCNN 2011 Special Session on Concept Drift and Learning Dynamic Environments
CIDUE 2011 Symposium on Computational Intelligence in Dynamic and Uncertain Environments
2010
HaCDAIS 2010 International Workshop on Handling Concept Drift in Adaptive Information Systems: Importance, Challenges and Solutions
ICMLA10 Special Session on Dynamic learning in non-stationary environments
SAC 2010 Data Streams Track at ACM Symposium on Applied Computing
SensorKDD 2010 International Workshop on Knowledge Discovery from Sensor Data
StreamKDD 2010 Novel Data Stream Pattern Mining Techniques
Concept Drift and Learning in Nonstationary Environments at IEEE World Congress on Computational Intelligence
MLMDS’2010 Special Session on Machine Learning Methods for Data Streams at the 10th International Conference on Intelligent Design and Applications, ISDA’10
References
Data mining
Machine learning
Data analysis | Concept drift | [
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"Artificial intelligence engineering",
"Machine learning"
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