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Pseudo-Hurler polydystrophy-Treatment-There is no cure for Pseudo-Hurler Polydystrophy/Mucolipidosis IIIA. Treatment is limited to controlling or reducing symptoms associated with this disorder. Physio-therapy, particularly hydrotherapy has proven effective at relieving muscle stiffness and increasing mobility. The use... | milkshake721/2.1M-wiki-STEM |
OpenTag-OpenTag-OpenTag is a DASH7 protocol stack and minimal Real-Time Operating System (RTOS), written in the C programming language. It is designed to run on microcontrollers or radio Systems on a Chip (SoC). OpenTag was engineered to be a very compact software package. However, with proper configuration, it can als... | milkshake721/2.1M-wiki-STEM |
OpenTag-Design philosophy-OpenTag implements DASH7 Mode 2, which specifies a monolithic system encompassing OSI layers one through six, part of layer seven, as well as the application layer. OpenTag is designed to be light and compact, as it is targeted to run on resource-constrained micro-controllers. As a monolithic ... | milkshake721/2.1M-wiki-STEM |
OpenTag-Features-It has a lightweight pre-emptive multitasking exokernel RTOS.
Most kernels use fixed priority tasks.
It contains a complete DASH7 Mode 2 protocol stack, including Remote wake up; Native query protocol; and UDP & SCTP adaptation layers.
It uses a Wear-leveling, Flash-based lightweight filesystem (Veelit... | milkshake721/2.1M-wiki-STEM |
OpenTag-Implementation-OpenTag implements a multitasking real-time kernel designed specifically to implement DASH7. User tasks can be managed by the kernel, and they can preempt the kernel, although they must be allocated at compile-time. The scheduling frequency, or kernel resolution, is implementation-dependent, but ... | milkshake721/2.1M-wiki-STEM |
OpenTag-Supported devices-At the time of writing, most OpenTag hardware is implemented on the Texas Instruments CC430 or MSP430 devices, which are endorsed for use with OpenTag. Current OpenTag source trees support many other MCUs and RF transceivers, however, such as various types of STM32, CC11xx, and Semtech SX12xx ... | milkshake721/2.1M-wiki-STEM |
Fry readability formula-Fry readability formula-The Fry readability formula (or Fry readability graph) is a readability metric for English texts, developed by Edward Fry.The grade reading level (or reading difficulty level) is calculated by the average number of sentences (y-axis) and syllables (x-axis) per hundred wor... | milkshake721/2.1M-wiki-STEM |
Fry readability formula-Fry readability formula-The formula and graph are often used to provide a common standard by which the readability of documents can be measured. It is sometimes used for regulatory purposes, such as in healthcare, to ensure publications have a level of readability that is understandable and acce... | milkshake721/2.1M-wiki-STEM |
Triphenylmethyl hexafluorophosphate-Triphenylmethyl hexafluorophosphate-Triphenylmethyl hexafluorophosphate (also triphenylcarbenium hexafluorophosphate, trityl hexafluorophosphate, or tritylium hexafluorophosphate) is an organic salt with the formula [(C6H5)3C]+[PF6]−, consisting of the triphenylcarbenium cation [(C6H... | milkshake721/2.1M-wiki-STEM |
Triphenylmethyl hexafluorophosphate-Preparation-Triphenylmethyl hexafluorophosphate can be prepared by combining silver hexafluorophosphate with triphenylmethyl chloride: Ag+[PF6]− + (C6H5)3CCl → [(C6H5)3C]+[PF6]− + AgClA second method involves protonolysis of triphenylmethanol: H[PF6] + (C6H5)3COH → [(C6H5)3C]+[PF6]− ... | milkshake721/2.1M-wiki-STEM |
Triphenylmethyl hexafluorophosphate-Structure and reactions-Triphenylmethyl hexafluorophosphate readily hydrolyzes, in a reaction that is the reverse of one of its syntheses: [(C6H5)3C]+[PF6]− + H2O → (C6H5)3COH + H[PF6]Triphenylmethyl hexafluorophosphate has been used for abstracting hydride (H−) from organic compound... | milkshake721/2.1M-wiki-STEM |
Termite-flg RNA motif-Termite-flg RNA motif-The Termite-flg RNA motif (also called tg-flg) is a conserved RNA structure identified by bioinformatics. Genomic sequences corresponding to Termite-flg RNAs have been identified only in uncultivated bacteria present in the termite hindgut. As of 2010 it has not been identifi... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Superheterodyne receiver-A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency. It was long ... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-Heterodyne Early Morse code radio broadcasts were produced using an alternator connected to a spark gap. The output signal was at a carrier frequency defined by the physical construction of the gap, modulated by the alternating current signal from the alternator. Since the output freque... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-In 1904, Ernst Alexanderson introduced the Alexanderson alternator, a device that directly produced radio frequency output with higher power and much higher efficiency than the older spark gap systems. In contrast to the spark gap, however, the output from the alternator was a pure carr... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-In 1905, Canadian inventor Reginald Fessenden came up with the idea of using two Alexanderson alternators operating at closely spaced frequencies to broadcast two signals, instead of one. The receiver would then receive both signals, and as part of the detection process, only the beat f... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-Fessenden coined the term "heterodyne", meaning "generated by a difference" (in frequency), to describe this system. The word is derived from the Greek roots hetero- "different", and -dyne "power". | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-Regeneration Morse code was widely used in the early days of radio because it was both easy to produce and easy to receive. In contrast to voice broadcasts, the output of the amplifier didn't have to closely match the modulation of the original signal. As a result, any number of simple ... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-In 1913, Edwin Howard Armstrong described a receiver system that used this effect to produce audible Morse code output using a single triode. The output of the amplifier taken at the anode was connected back to the input through a "tickler", causing feedback that drove input signals wel... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-Armstrong referred to this concept as a regenerative receiver, and it immediately became one of the most widely used systems of its era. Many radio systems of the 1920s were based on the regenerative principle, and it continued to be used in specialized roles into the 1940s, for instanc... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-The regenerative system was highly non-linear, amplifying any signal above a certain threshold by a huge amount, sometimes so large it caused it to turn into a transmitter (which was the entire basis of the original IFF system). In RDF, the strength of the signal is used to determine th... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-To address this need, RDF systems of the era used triodes operating below unity. To get a usable signal from such a system, tens or even hundreds of triodes had to be used, connected together anode-to-grid. These amplifiers drew enormous amounts of power and required a team of maintenan... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-Superheterodyne Although a number of researchers discovered the superheterodyne concept, filing patents only months apart (see below), American engineer Edwin Armstrong is often credited with the concept. He came across it while considering better ways to produce RDF receivers. He had c... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-It had been noticed that when a regenerative receiver went into oscillation, other nearby receivers would start picking up other stations as well. Armstrong (and others) eventually deduced that this was caused by a "supersonic heterodyne" between the station's carrier frequency and the ... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-For instance, consider a lone receiver that was tuned to a station at 300 kHz. If a second receiver is set up nearby and set to 400 kHz with high gain, it will begin to give off a 400 kHz signal that will be received in the first receiver. In that receiver, the two signals will mix to p... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-Armstrong realized that this effect was a potential solution to the "short wave" amplification problem, as the "difference" output still retained its original modulation, but on a lower carrier frequency. In the example above, one can amplify the 100 kHz beat signal and retrieve the ori... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-For instance, to receive a signal at 1500 kHz, far beyond the range of efficient amplification at the time, one could set up an oscillator at, for example, 1560 kHz. Armstrong referred to this as the "local oscillator" or LO. As its signal was being fed into a second receiver in the sam... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-In December 1919, Major E. H. Armstrong gave publicity to an indirect method of obtaining short-wave amplification, called the super-heterodyne. The idea is to reduce the incoming frequency, which may be, for example 1,500,000 cycles (200 meters), to some suitable super-audible frequenc... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-The "trick" to the superheterodyne is that by changing the LO frequency you can tune in different stations. For instance, to receive a signal at 1300 kHz, one could tune the LO to 1360 kHz, resulting in the same 60 kHz IF. This means the amplifier section can be tuned to operate at a si... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-Development Armstrong put his ideas into practice, and the technique was soon adopted by the military. It was less popular when commercial radio broadcasting began in the 1920s, mostly due to the need for an extra tube (for the oscillator), the generally higher cost of the receiver, and... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-In the 1920s, at these low frequencies, commercial IF filters looked very similar to 1920s audio interstage coupling transformers, had similar construction, and were wired up in an almost identical manner, so they were referred to as "IF transformers". By the mid-1930s, superheterodynes... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-By the 1930s, improvements in vacuum tube technology rapidly eroded the TRF receiver's cost advantages, and the explosion in the number of broadcasting stations created a demand for cheaper, higher-performance receivers. | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-The introduction of an additional grid in a vacuum tube, but before the more modern screen-grid tetrode, included the tetrode with two control grids; this tube combined the mixer and oscillator functions, first used in the so-called autodyne mixer. This was rapidly followed by the intro... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-By the mid-1930s, commercial production of TRF receivers was largely replaced by superheterodyne receivers. By the 1940s, the vacuum-tube superheterodyne AM broadcast receiver was refined into a cheap-to-manufacture design called the "All American Five" because it used five vacuum tubes... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-Patent battles French engineer Lucien Lévy filed a patent application for the superheterodyne principle in August 1917 with brevet n° 493660. Armstrong also filed his patent in 1917. Levy filed his original disclosure about seven months before Armstrong's. | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-History-German inventor Walter H. Schottky also filed a patent in 1918.At first the US recognised Armstrong as the inventor, and his US Patent 1,342,885 was issued on 8 June 1920. After various changes and court hearings Lévy was awarded US patent No 1,734,938 that included seven of the nine cl... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Principle of operation-The diagram at right shows the block diagram of a typical single-conversion superheterodyne receiver. The diagram has blocks that are common to superheterodyne receivers, with only the RF amplifier being optional. | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Principle of operation-The antenna collects the radio signal. The tuned RF stage with optional RF amplifier provides some initial selectivity; it is necessary to suppress the image frequency (see below), and may also serve to prevent strong out-of-passband signals from saturating the initial am... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Principle of operation-Circuit description To receive a radio signal, a suitable antenna is required. The output of the antenna may be very small, often only a few microvolts. The signal from the antenna is tuned and may be amplified in a so-called radio frequency (RF) amplifier, although this ... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Principle of operation-Local oscillator and mixer The signal is then fed into a circuit where it is mixed with a sine wave from a variable frequency oscillator known as the local oscillator (LO). The mixer uses a non-linear component to produce both sum and difference beat frequencies signals, ... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Principle of operation-The frequency of the local oscillator fLO is set so the desired reception radio frequency fRF mixes to fIF. There are two choices for the local oscillator frequency because the dominant mixer products are at fRF ± fLO. If the local oscillator frequency is less than the de... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Principle of operation-The mixer will process not only the desired input signal at fRF, but also all signals present at its inputs. There will be many mixer products (heterodynes). Most other signals produced by the mixer (such as due to stations at nearby frequencies) can be filtered out in th... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Principle of operation-To suppress the unwanted image, the tuning of the RF stage and the LO may need to "track" each other. In some cases, a narrow-band receiver can have a fixed tuned RF amplifier. In that case, only the local oscillator frequency is changed. In most cases, a receiver's input... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Principle of operation-IF amplifier The stages of an intermediate frequency amplifier ("IF amplifier" or "IF strip") are tuned to a fixed frequency that does not change as the receiving frequency changes. The fixed frequency simplifies optimization of the IF amplifier. The IF amplifier is selec... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Principle of operation-Normally, the IF center frequency fIF is chosen to be less than the range of desired reception frequencies fRF. That is because it is easier and less expensive to get high selectivity at a lower frequency using tuned circuits. The bandwidth of a tuned circuit with a certa... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Principle of operation-However, in many modern receivers designed for reception over a wide frequency range (e.g. scanners and spectrum analyzers) a first IF frequency higher than the reception frequency is employed in a double conversion configuration. For instance, the Rohde & Schwarz EK-070 ... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Principle of operation-To avoid interference to receivers, licensing authorities will avoid assigning common IF frequencies to transmitting stations. Standard intermediate frequencies used are 455 kHz for medium-wave AM radio, 10.7 MHz for broadcast FM receivers, 38.9 MHz (Europe) or 45 MHz (US... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Principle of operation-In early superhets, the IF stage was often a regenerative stage providing the sensitivity and selectivity with fewer components. Such superhets were called super-gainers or regenerodynes. This is also called a Q multiplier, involving a small modification to an existing re... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Principle of operation-IF bandpass filter The IF stage includes a filter and/or multiple tuned circuits to achieve the desired selectivity. This filtering must have a band pass equal to or less than the frequency spacing between adjacent broadcast channels. Ideally a filter would have a high at... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Principle of operation-Demodulator The received signal is now processed by the demodulator stage where the audio signal (or other baseband signal) is recovered and then further amplified. AM demodulation requires envelope detection, which can be achieved by means of rectification and a low-pass... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Principle of operation-When so-called high-side injection has been used, where the local oscillator is at a higher frequency than the received signal (as is common), then the frequency spectrum of the original signal will be reversed. This must be taken into account by the demodulator (and in t... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Multiple conversion-To overcome obstacles such as image response, some receivers use multiple successive stages of frequency conversion and multiple IFs of different values. A receiver with two frequency conversions and IFs is called a dual conversion superheterodyne, and one with three IFs is ... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Multiple conversion-The main reason that this is done is that with a single IF there is a tradeoff between low image response and selectivity. The separation between the received frequency and the image frequency is equal to twice the IF frequency, so the higher the IF, the easier it is to desi... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Multiple conversion-For example, for a receiver that can tune from 500 kHz to 30 MHz, three frequency converters might be used. With a 455 kHz IF it is easy to get adequate front end selectivity with broadcast band (under 1600 kHz) signals. For example, if the station being received is on 600 k... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Multiple conversion-However at 30 MHz, things are different. The oscillator would be set to 30.455 MHz to produce a 455 kHz IF, but a station on 30.910 would also produce a 455 kHz beat, so both stations would be heard at the same time. But it is virtually impossible to design an RF tuned circu... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Multiple conversion-For example, the ranges 29 MHz to 30 MHz; 28 MHz to 29 MHz etc. might be converted down to 2 MHz to 3 MHz, there they can be tuned more conveniently. This is often done by first converting each "block" up to a higher frequency (typically 40 MHz) and then using a second mixer... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Modern designs-Microprocessor technology allows replacing the superheterodyne receiver design by a software-defined radio architecture, where the IF processing after the initial IF filter is implemented in software. This technique is already in use in certain designs, such as very low-cost FM r... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Advantages and disadvantages-Superheterodyne receivers have essentially replaced all previous receiver designs. The development of modern semiconductor electronics negated the advantages of designs (such as the regenerative receiver) that used fewer vacuum tubes. The superheterodyne receiver of... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Advantages and disadvantages-Although the advantages of the superhet design are overwhelming, there are a few drawbacks that need to be tackled in practice. | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Advantages and disadvantages-Image frequency (fIMAGE) One major disadvantage to the superheterodyne receiver is the problem of image frequency. In heterodyne receivers, an image frequency is an undesired input frequency equal to the station frequency plus (or minus) twice the intermediate frequ... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Advantages and disadvantages-if (high side injection) if (low side injection) For example, an AM broadcast station at 580 kHz is tuned on a receiver with a 455 kHz IF. The local oscillator is tuned to 580 + 455 = 1035 kHz. But a signal at 580 + 455 + 455 = 1490 kHz is also 455 kHz away from t... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Advantages and disadvantages-The unwanted frequency is called the image of the wanted frequency, because it is the "mirror image" of the desired frequency reflected about fLO . A receiver with inadequate filtering at its input will pick up signals at two different frequencies simultaneously: t... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Advantages and disadvantages-Sensitivity to the image frequency can be minimized only by (1) a filter that precedes the mixer or (2) a more complex mixer circuit to suppress the image; this is rarely used. In most tunable receivers using a single IF frequency, the RF stage includes at least one... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Advantages and disadvantages-Image rejection is an important factor in choosing the intermediate frequency of a receiver. The farther apart the bandpass frequency and the image frequency are, the more the bandpass filter will attenuate any interfering image signal. Since the frequency separatio... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Advantages and disadvantages-The ability of a receiver to reject interfering signals at the image frequency is measured by the image rejection ratio. This is the ratio (in decibels) of the output of the receiver from a signal at the received frequency, to its output for an equal-strength signal... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Advantages and disadvantages-Local oscillator radiation is most prominent in receivers in which the antenna signal is connected directly to the mixer (which itself receives the local oscillator signal) rather than from receivers in which an RF amplifier stage is used in between. Thus it is more... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Advantages and disadvantages-Local oscillator sideband noise Local oscillators typically generate a single frequency signal that has negligible amplitude modulation but some random phase modulation which spreads some of the signal's energy into sideband frequencies. That causes a corresponding ... | milkshake721/2.1M-wiki-STEM |
Superheterodyne receiver-Terminology-First detector, second detector The mixer tube or transistor is sometimes called the first detector, while the demodulator that extracts the modulation from the IF signal is called the second detector. In a dual-conversion superhet there are two mixers, so the demodulator is called ... | milkshake721/2.1M-wiki-STEM |
Soundcheck-Soundcheck-A soundcheck is the preparation that takes place before a concert, speech, or similar performance to adjust the sound on the venue's sound reinforcement or public address system. The performer and the audio engineers run through a small portion of the upcoming show to ensure the venue's front of h... | milkshake721/2.1M-wiki-STEM |
Soundcheck-Soundcheck-Sound checks are especially important for rock music shows and other performances that rely heavily on sound reinforcement systems. | milkshake721/2.1M-wiki-STEM |
Soundcheck-Processes-Soundchecks are usually conducted prior to audience entry to the venue. The soundcheck may start with the rhythm section, and then go on to the melody section and vocalists. After technical adjustments have been completed by the sound crew, the performers leave the stage and the audience is admitte... | milkshake721/2.1M-wiki-STEM |
GIWS (software)-GIWS (software)-GIWS is a wrapper generator intended to simplify calling Java from C or C++ by automatically generating the necessary JNI code.
GIWS is released under the CeCILL license. | milkshake721/2.1M-wiki-STEM |
GIWS (software)-Example-The following Java class does some simple computation.
GIWS gives the capability to call it from C++.
To generate the binding, GIWS uses a XML declaration. GIWS will generate the JNI code to call the Java object. | milkshake721/2.1M-wiki-STEM |
Smithsonian Transcription Center-Smithsonian Transcription Center-The Smithsonian Transcription Center is a crowdsourcing transcription project that aims to assist with the preservation and digitization of handwritten material in the Smithsonian Institution. The Transcription Center cites five reasons why transcription... | milkshake721/2.1M-wiki-STEM |
Simple set-Simple set-In computability theory, a subset of the natural numbers is called simple if it is computably enumerable (c.e.) and co-infinite (i.e. its complement is infinite), but every infinite subset of its complement is not c.e.. Simple sets are examples of c.e. sets that are not computable. | milkshake721/2.1M-wiki-STEM |
Simple set-Relation to Post's problem-Simple sets were devised by Emil Leon Post in the search for a non-Turing-complete c.e. set. Whether such sets exist is known as Post's problem. Post had to prove two things in order to obtain his result: that the simple set A is not computable, and that the K, the halting problem,... | milkshake721/2.1M-wiki-STEM |
Simple set-Relation to Post's problem-Post's idea was validated by Friedberg and Muchnik in the 1950s using a novel technique called the priority method. They give a construction for a set that is simple (and thus non-computable), but fails to compute the halting problem. | milkshake721/2.1M-wiki-STEM |
Simple set-Formal definitions and some properties-In what follows, We denotes a standard uniformly c.e. listing of all the c.e. sets.
A set I⊆N is called immune if I is infinite, but for every index e , we have infinite ⟹We⊈I . Or equivalently: there is no infinite subset of I that is c.e..
A set S⊆N is called s... | milkshake721/2.1M-wiki-STEM |
Lowbridge double-deck bus-Lowbridge double-deck bus-A lowbridge double-deck bus is a double-decker bus that has an asymmetric interior layout, enabling the overall height of the vehicle to be reduced compared to that of a conventional double-decker bus. The upper deck gangway is offset to one side of the vehicle, norma... | milkshake721/2.1M-wiki-STEM |
Lowbridge double-deck bus-Origins-The lowbridge design was introduced and patented by Leyland in 1927 on their Titan TD1 chassis. Early examples were delivered to Glasgow Corporation amongst other operators. One of the Glasgow vehicles is preserved at the Scottish Vintage Bus Museum, Lathalmond, Fife. | milkshake721/2.1M-wiki-STEM |
Lowbridge double-deck bus-Disadvantages-A major disadvantage of this layout was the inconvenient seating layout, with four-abreast seats upstairs making it difficult for passengers to manoeuvre past each other if those farthest from the gangway needed to alight first. A second disadvantage was the restricted headroom f... | milkshake721/2.1M-wiki-STEM |
Lowbridge double-deck bus-Alternatives-At first, there was no viable alternative to the lowbridge design, apart from the use of single-decker bus. However, the lowbridge type started to become obsolete when low-height chassis were developed, which used a dropped-center rear axle to enable the lower deck gangway to be l... | milkshake721/2.1M-wiki-STEM |
Lowbridge double-deck bus-Alternatives-When the rear-engined Leyland Atlantean was first introduced in 1958, it did not have a dropped-centre rear axle, even though the prototype had featured one. As a result, some Atlanteans were built to a "semi-lowbridge" layout, with the front half of the upper deck laid out conven... | milkshake721/2.1M-wiki-STEM |
Lowbridge double-deck bus-Alternatives-A special situation existed in Beverley in the East Riding of Yorkshire, where buses had to pass underneath the arched structure of the Beverley Bar. To facilitate this, East Yorkshire Motor Services had a number of double-deckers built with special "Gothic" roofs of severely-arch... | milkshake721/2.1M-wiki-STEM |
Lowbridge double-deck bus-Notable vehicles-A notable lowbridge bus is Barton Transport's no. 861, registered 861 HAL. It is unique in combining a low-height chassis (Dennis Loline II) with lowbridge bodywork, built by Northern Counties for navigating a very low bridge at Sawley that was impassable for conventional lowb... | milkshake721/2.1M-wiki-STEM |
Climate across Cretaceous–Paleogene boundary-Climate across Cretaceous–Paleogene boundary-The climate across the Cretaceous–Paleogene boundary (K–Pg or formerly the K–T boundary) is very important to geologic time as it marks a catastrophic global extinction event. Numerous theories have been proposed as to why this ex... | milkshake721/2.1M-wiki-STEM |
Climate across Cretaceous–Paleogene boundary-K–Pg boundary-The K–Pg (formerly K–T) boundary is a thin band of sediment that dates back to 66 million years ago, and is found as a consistent layer all over the planet in over 100 known different locations. K and T are the abbreviations for the Cretaceous and Tertiary peri... | milkshake721/2.1M-wiki-STEM |
Climate across Cretaceous–Paleogene boundary-Late Cretaceous to K–Pg boundary climate-Late Cretaceous climate The Cretaceous Period (145–66 Ma), overall, had a relatively warm climate which resulted in high eustatic sea levels and created numerous shallow inland seas. In the Late Cretaceous, the climate was much warmer... | milkshake721/2.1M-wiki-STEM |
Climate across Cretaceous–Paleogene boundary-Late Cretaceous to K–Pg boundary climate-Climate across the K–Pg boundary Across the K–Pg boundary, surface productivity decreased slightly. A temperature gradient of ~0.4 °C per degree of latitude is proposed for North America across the K–Pg boundary. These data of terrest... | milkshake721/2.1M-wiki-STEM |
Climate across Cretaceous–Paleogene boundary-Late Cretaceous to K–Pg boundary climate-The impact pushed atmospheric CO2 levels up from 350 to 500 ppm to approximately 2300 ppm, which would have been sufficient to warm the Earth's surface by ~7.5 °C in the absence of counter forcing by sulfate aerosols.
It is unclear wh... | milkshake721/2.1M-wiki-STEM |
Climate across Cretaceous–Paleogene boundary-Early Paleogene climate-The Paleocene (the first epoch of the Paleogene) immediately followed the asteroid impact that destroyed the dinosaurs and the Cretaceous world. It marks the transition between the dinosaurs of the Mesozoic and the emergence of the larger mammals of t... | milkshake721/2.1M-wiki-STEM |
Climate across Cretaceous–Paleogene boundary-Mass extinction theories-The events at the K–Pg boundary were the influences of several theories on how the climate change and extinction event could have taken place. These hypotheses have centered on either impact events or increased volcanism or both. The consensus among ... | milkshake721/2.1M-wiki-STEM |
Climate across Cretaceous–Paleogene boundary-Mass extinction theories-Asteroid impact The theory with the most support to date is for an impact by one or more asteroids. The Alvarez hypothesis, proposed in 1980, gave evidence for this. Luis Alvarez and a team of researchers found sedimentary layers all over the world a... | milkshake721/2.1M-wiki-STEM |
Climate across Cretaceous–Paleogene boundary-Mass extinction theories-They concluded that the asteroid was about 9.97 kilometers in diameter which would cause an impact with about the same energy as 100 trillion tons of TNT. An impact of that magnitude would then create a large dust cloud that would block sunlight and ... | milkshake721/2.1M-wiki-STEM |
Climate across Cretaceous–Paleogene boundary-Mass extinction theories-Deccan Traps The Deccan Trap eruptions were associated with a deep mantle plume. The theory suggests that about 66 million years ago, the mantle plume at the Réunion hotspot burned through the Earth's crust and flooded western India with basaltic lav... | milkshake721/2.1M-wiki-STEM |
Climate across Cretaceous–Paleogene boundary-Mass extinction theories-Sea level A theory for sea level fall in the Maastrichtian time period, the latest age of the late Cretaceous, has been proposed as evidence. It shows that sea level fell more at this time of the Cenozoic than any time during the Mesozoic. In rock la... | milkshake721/2.1M-wiki-STEM |
Climate across Cretaceous–Paleogene boundary-Species affected-Species that depended on photosynthesis suffered the most as the sunlight was blocked by atmospheric particles which reduced the solar energy that reached that Earth's surface. Photosynthesizing organisms such as phytoplankton and plants started to die out w... | milkshake721/2.1M-wiki-STEM |
Climate across Cretaceous–Paleogene boundary-Species affected-Omnivores, insectivores and carrion-eaters survived the extinction event, due to the increased availability of their food sources. Mammals and birds that survived the extinction fed on insects, worms, and snails, which then fed on dead plant and animal matte... | milkshake721/2.1M-wiki-STEM |
Low voltage-Low voltage-In electrical engineering, low voltage is a relative term, the definition varying by context. Different definitions are used in electric energy transmission and distribution, compared with electronics design. Electrical safety codes define "low voltage" circuits that are exempt from the protecti... | milkshake721/2.1M-wiki-STEM |
Low voltage-IEC Definition-a May depend on the applicable standard used. | milkshake721/2.1M-wiki-STEM |
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