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Piston Effect
Piston effect refers to the forced-air flow inside a tunnel or shaft caused by moving vehicles. It is one of numerous phenomena that engineers and designers must consider when developing a range of structures. Cause In open air, when a vehicle travels along, air pushed aside can move in any direction except into the ground. Inside a tunnel, air is confined by the tunnel walls to move along the tunnel. Behind the moving vehicle, as air has been pushed away, suction is created, and air is pulled to flow into the tunnel. In addition, because of fluid viscosity, the surface of the vehicle drags the air to flow with vehicle, a force experienced as skin drag by the vehicle. This movement of air by the vehicle is analogous to the operation of a mechanical piston as inside a reciprocating compressor gas pump, hence the name "piston effect". The effect is also similar to the pressure fluctuations inside drainage pipes as waste water pushes air in front of it. The piston effect is v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forced-air
A forced-air central heating system is one which uses air as its heat transfer medium. These systems rely on ductwork, vents, and plenums as means of air distribution, separate from the actual heating and air conditioning systems. The return plenum carries the air from several large return grills (vents) to a central air handler for re-heating. The supply plenum directs air from the central unit to the rooms which the system is designed to heat. Regardless of type, all air handlers consist of an air filter, blower, heat exchanger/element/coil, and various controls. Like any other kind of central heating system, thermostats are used to control forced air heating systems. Forced air heating is the type of central heating most commonly installed in North America. It is much less common in Europe, where hydronic heating predominates, especially in the form of hot-water radiators. Types Natural gas/propane/oil/coal/wood *Heat is produced via combustion of fuel. *A heat exchang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elevator
An elevator (American English) or lift (Commonwealth English) is a machine that vertically transports people or freight between levels. They are typically powered by electric motors that drive traction cables and counterweight systems such as a hoist, although some pump hydraulic fluid to raise a cylindrical piston like a jack. Elevators are used in agriculture and manufacturing to lift materials. There are various types, like chain and bucket elevators, grain augers, and hay elevators. Modern buildings often have elevators to ensure accessibility, especially where ramps aren't feasible. High-speed elevators are common in skyscrapers. Some elevators can even move horizontally. History Pre-industrial era The earliest known reference to an elevator is in the works of the Roman architect Vitruvius, who reported that Archimedes ( – ) built his first elevator probably in 236 BC. Sources from later periods mention elevators as cabs on a hemp rope, powered by people o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Railway Tunnels
Rail transport (also known as train transport) is a means of transport using wheeled vehicles running in tracks, which usually consist of two parallel steel rails. Rail transport is one of the two primary means of land transport, next to road transport. It is used for about 8% of passenger and freight transport globally, thanks to its energy efficiency and potentially high speed.Rolling stock on rails generally encounters lower frictional resistance than rubber-tyred road vehicles, allowing rail cars to be coupled into longer trains. Power is usually provided by diesel or electric locomotives. While railway transport is capital-intensive and less flexible than road transport, it can carry heavy loads of passengers and cargo with greater energy efficiency and safety. Precursors of railways driven by human or animal power have existed since antiquity, but modern rail transport began with the invention of the steam locomotive in the United Kingdom at the beginning of the 19th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plumbing Drainage Venting
A drain-waste-vent system (or DWV) is the combination of pipes and plumbing fittings that captures sewage and greywater within a structure and routes it toward a water treatment system. It includes venting to the exterior environment to prevent a vacuum from forming and impeding fixtures such as sinks, showers, and toilets from draining freely, and employs water-filled traps to block dangerous sewer gasses from entering a plumbed structure. DWV systems capture both sewage and greywater within a structure and safely route it out via the low point of its "soil stack" to a waste treatment system, either via a municipal sanitary sewer system, or to a septic tank and leach field. (Cesspits are generally prohibited in developed areas.) For such drainage systems to work properly it is crucial that neutral air pressure be maintained within all pipes, allowing free gravity flow of water and sewage through drains. It is critical that a sufficient fall gradient (downward slope) be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silencer (firearms)
A silencer, also known as a sound suppressor, suppressor, or sound moderator, is a gun barrel#Muzzle, muzzle device that suppresses the muzzle blast, blast created when a gun (firearm or airgun) is discharged, thereby reducing the sound intensity, acoustic intensity of the muzzle report (sound of a gunshot) and muzzle rise, jump, by modulating the speed and pressure of the propellant gas released from the muzzle. Like other muzzle devices, a silencer can be a detachable accessory mounted to the muzzle or an integral part of the gun barrel, barrel. A typical silencer is a metallic (usually stainless steel or titanium) cylinder (firearms), cylinder containing numerous internal sound baffles, with a hollow bore to allow the bullet to exit normally. During firing, the bullet passes through the bore with little hindrance, but most of the expanding gas ejecta behind it is redirected through a longer and convoluted escape path created by the baffles, prolonging the release time. This ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerodynamic
Aerodynamics () is the study of the motion of atmosphere of Earth, air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dynamics and its subfield of gas dynamics, and is an important domain of study in aeronautics. The term ''aerodynamics'' is often used synonymously with gas dynamics, the difference being that "gas dynamics" applies to the study of the motion of all gases, and is not limited to air. The formal study of aerodynamics began in the modern sense in the eighteenth century, although observations of fundamental concepts such as aerodynamic drag were recorded much earlier. Most of the early efforts in aerodynamics were directed toward achieving Aircraft#Heavier-than-air – aerodynes, heavier-than-air flight, which was first demonstrated by Otto Lilienthal in 1891. Since then, the use of aerodynamics through mathematical analysis, empirical approximations, wind tunnel experimentation, and computer si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shinkansen
The , colloquially known in English as the bullet train, is a network of high-speed railway lines in Japan. It was initially built to connect distant Japanese regions with Tokyo, the capital, to aid economic growth and development. Beyond long-distance travel, some sections around the List of metropolitan areas in Japan, largest metropolitan areas are used as a commuter rail network. It is owned by the Japan Railway Construction, Transport and Technology Agency and operated by five Japan Railways Group companies. Starting with the Tokaido Shinkansen () in 1964, the network has expanded to consist of of lines with maximum speeds of , of Mini-shinkansen lines with a maximum speed of , and of spur lines with Shinkansen services. The network links most major cities on the islands of Honshu and Kyushu, and connects to Hakodate on the northern island of Hokkaido. An extension to Sapporo is under construction and was initially scheduled to open by fiscal year 2030, but in December ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compression Wave
Longitudinal waves are waves which oscillate in the direction which is parallel to the direction in which the wave travels and displacement of the medium is in the same (or opposite) direction of the wave propagation. Mechanical longitudinal waves are also called ''compressional'' or compression waves, because they produce compression and rarefaction when travelling through a medium, and pressure waves, because they produce increases and decreases in pressure. A wave along the length of a stretched Slinky toy, where the distance between coils increases and decreases, is a good visualization. Real-world examples include sound waves (vibrations in pressure, a particle of displacement, and particle velocity propagated in an elastic medium) and seismic P waves (created by earthquakes and explosions). The other main type of wave is the transverse wave, in which the displacements of the medium are at right angles to the direction of propagation. Transverse waves, for instan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sonic Boom
A sonic boom is a sound associated with shock waves created when an object travels through the air faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding similar to an explosion or a thunderclap to the human ear. The crack of a supersonic bullet passing overhead or the crack of a bullwhip are examples of a small sonic boom. Sonic booms due to large supersonic aircraft can be particularly loud and startling, tend to awaken people, and may cause minor damage to some structures. This led to the prohibition of routine supersonic flight overland. Although sonic booms cannot be completely prevented, research suggests that with careful shaping of the vehicle, the nuisance due to sonic booms may be reduced to the point that overland supersonic flight may become a feasible option. A sonic boom does not occur only at the moment an object crosses the sound barrier and neither is it heard in all directions emanating from the supersonic objec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shock Wave
In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a medium, but is characterized by an abrupt, nearly discontinuous, change in pressure, temperature, and density of the medium. For the purpose of comparison, in supersonic speed, supersonic flows, additional increased expansion may be achieved through an expansion fan, also known as a Prandtl–Meyer expansion fan. The accompanying expansion wave may approach and eventually collide and recombine with the shock wave, creating a process of destructive interference. The sonic boom associated with the passage of a supersonic aircraft is a type of sound wave produced by Wave interference, constructive interference. Unlike solitons (another kind of nonlinear wave), the energy and speed of a shock wave alone dissipates relatively quickly with distan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tgv Tunnel With Hood
The TGV (; , , 'high-speed train') is France's intercity high-speed rail service. With commercial operating speeds of up to on the newer lines, the TGV was conceived at the same period as other technological projects such as the Ariane 1 rocket and Concorde supersonic airliner; sponsored by the Government of France, those funding programmes were known as (' national champion') policies. In 2023 the TGV network in France carried 122 million passengers. The state-owned SNCF started working on a high-speed rail network in 1966. It presented the project to President Georges Pompidou in 1974 who approved it. Originally designed as turbotrains to be powered by gas turbines, TGV prototypes evolved into electric trains with the 1973 oil crisis. In 1976 the SNCF ordered 87 high-speed trains from Alstom. Following the inaugural service between Paris and Lyon in 1981 on the LGV Sud-Est, the network, centred on Paris, has expanded to connect major cities across France, including Marseill ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Imperial College Press
Imperial College Press (ICP) was formed in 1995 as a partnership between Imperial College of Science, Technology and Medicine in London and World Scientific publishing. This publishing house was awarded the rights, by The Nobel Foundation, Sweden, to publish ''The Nobel Prize: The First 100 years'', edited by Agneta Wallin Levinovitz and Nils Ringertz. They publish areas of teaching and research at Imperial College: Chemistry, Computer Science, Economics, Finance & Management, Engineering, Environmental Science, Life Sciences, Mathematics, Medicine & Healthcare, and Physics. As of August 2016, ICP has been fully incorporated into World Scientific under the new imprint, ''World Scientific Europe''. Selected journals * '' Journal of Bioinformatics and Computational Biology'' * '' Journal of Integrative Neuroscience'' * ''International Journal of Innovation Management The ''International Journal of Innovation Management'' is the official journal of the International Soci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
