Soyjak.Party / The Sharty - The altchan born from the ashes of /qa/; also a containment thread

Destacado
1783979609343.png
 
The elk (pl.: elk or elks; Cervus canadensis) or wapiti (pronounced /ˈwɒpəti/[3][4]) is the second largest species within the deer family, Cervidae, and one of the largest terrestrial mammals in its native range of North America and Central and East Asia. The word "elk" originally referred to the European variety of the moose, Alces alces, but was transferred to Cervus canadensis by North American colonists.
 
Trellis coded modulation (TCM) is a modulation scheme that transmits information with high efficiency over band-limited channels such as telephone lines. Gottfried Ungerboeck invented trellis modulation while working for IBM in the 1970s, and first described it in a conference paper in 1976. It went largely unnoticed, however, until he published a new, detailed exposition in 1982 that achieved sudden and widespread recognition.

In the late 1980s, modems operating over plain old telephone service (POTS) typically achieved 9.6 kbit/s by employing four bits per symbol QAM modulation at 2,400 baud (symbols/second). This bit rate ceiling existed despite the best efforts of many researchers, and some engineers predicted that without a major upgrade of the public phone infrastructure, the maximum achievable rate for a POTS modem might be 14 kbit/s for two-way communication (3,429 baud × 4 bits/symbol, using QAM).[citation needed]

14 kbit/s is only 40% of the theoretical maximum bit rate predicted by Shannon's theorem for POTS lines (approximately 35 kbit/s).[1] Ungerboeck's theories demonstrated that there was considerable untapped potential in the system, and by applying the concept to new modem standards, speed rapidly increased to 14.4, 28.8 and ultimately 33.6 kbit/s.
 
The name "wapiti" is derived from a Shawnee and Cree word meaning "white rump", after the distinctive light fur around the tail region which the animals may fluff-up or raise to signal their agitation or distress to one another, when fleeing perceived threats, or among males courting females and sparring for dominance. A similar trait is seen in other artiodactyl species, like the bighorn sheep, pronghorn and the white-tailed deer, to varying degrees.

Elk dwell in open forest and forest-edge habitats, grazing on grasses and sedges and browsing higher-growing plants, leaves, twigs and bark. Male elk have large, blood- and nerve-filled antlers, which they routinely shed each year as the weather warms. Males also engage in ritualized mating behaviors during the mating season, including posturing to attract females, antler-wrestling (sparring), and bugling, a loud series of throaty whistles, bellows, screams, and other vocalizations that establish dominance over other males and aim to attract females.
 
As electronic computers became larger and more complex, cooling of the active components became a critical factor for reliable operation. Early vacuum-tube computers, with relatively large cabinets, could rely on natural or forced air circulation for cooling. However, solid-state devices were packed much more densely and had lower allowable operating temperatures.

Starting in 1965, IBM and other manufacturers of mainframe computers sponsored intensive research into the physics of cooling densely packed integrated circuits. Many air and liquid cooling systems were devised and investigated, using methods such as natural and forced convection, direct air impingement, direct liquid immersion and forced convection, pool boiling, falling films, flow boiling, and liquid jet impingement. Mathematical analysis was used to predict temperature rises of components for each possible cooling system geometry.[3]

IBM developed three generations of the Thermal Conduction Module (TCM) which used a water-cooled cold plate in direct thermal contact with integrated circuit packages. Each package had a thermally conductive pin pressed onto it, and helium gas surrounded chips and heat-conducting pins. The design could remove up to 27 watts from a chip and up to 2000 watts per module, while maintaining chip package temperatures of around 50 °C (122 °F). Systems using TCMs were the 3081 family (1980), ES/3090 (1984) and some models of the ES/9000 (1990).[3] In the IBM 3081 processor, TCMs allowed up to 2700 watts on a single printed circuit board while maintaining chip temperature at 69 °C (156 °F).[4] Thermal conduction modules using water cooling were also used in mainframe systems manufactured by other companies including Mitsubishi and Fujitsu.

The Cray-1 supercomputer designed in 1976 had a distinctive cooling system. The machine was only 77 inches (2,000 mm) in height and 56+1⁄2 inches (1,440 mm) in diameter, and consumed up to 115 kilowatts; this is comparable to the average power consumption of a few dozen Western homes or a medium-sized car. The integrated circuits used in the machine were the fastest available at the time, using emitter-coupled logic; however, the speed was accompanied by high power consumption compared to later CMOS devices.

Heat removal was critical. Refrigerant was circulated through piping embedded in vertical cooling bars in twelve columnar sections of the machine. Each of the 1662 printed circuit modules of the machine had a copper core and was clamped to the cooling bar. The system was designed to maintain the cases of integrated circuits at no more than 54 °C (129 °F), with refrigerant circulating at 21 °C (70 °F). Final heat rejection was through a water-cooled condenser.[5] Piping, heat exchangers, and pumps for the cooling system were arranged in an upholstered bench seat around the outside of the base of the computer. About 20 percent of the machine's weight in operation was refrigerant.[6]

In the later Cray-2, with its more densely packed modules, Seymour Cray had trouble effectively cooling the machine using the metal conduction technique with mechanical refrigeration, so he switched to 'liquid immersion' cooling. This method involved filling the chassis of the Cray-2 with a liquid called Fluorinert. Fluorinert, as its name implies, is an inert liquid that does not interfere with the operation of electronic components. As the components came to operating temperature, the heat would dissipate into the Fluorinert, which was pumped out of the machine to a chilled water heat exchanger.[7]

Performance per watt of modern systems has greatly improved; many more computations can be carried out with a given power consumption than was possible with the integrated circuits of the 1980s and 1990s. Recent supercomputer projects such as Blue Gene rely on air cooling, which reduces cost, complexity, and size of systems compared to liquid cooling.
 
Due to Fluorinert's high global warming potential, alternative low global warming potential agents were found and sold under the brand names Novec Engineered Fluids. There are two types of chemical compounds under Novec branding for similar industrial applications:

Segregated Hydrofluoroether (HFE) compounds including Novec 7000, 7100, 7200, 7300, 7500, and 7700 has lower global warming potential of ~300.[8]
Fluoroketones (FK) compounds including Novec 649 and 774 has much lower global warming potential of 1. Novec 649 has similar thermo-physical properties to FC-72 making it a good drop-in replacement for low temperature heat transfer.[9]
 
Destacado
Debes iniciar sesión o registrarte para responder aquí.
Atrás
Top Abajo