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Ground Vibration Boom
Ground vibration boom is a phenomenon of very large increase in ground vibrations generated by high-speed railway trains travelling at speeds higher than the velocity of Rayleigh surface waves in the supporting ground. Technical background This phenomenon, which is similar to a sonic boom from supersonic aircraft, was theoretically predicted in 1994. Its first experimental observation took place in 1997-1998 on the newly built high-speed railway line in Sweden (from Gothenburg to Malmo) for high-speed trains X 2000. At some locations along this line characterised by very soft ground (near Ledsgard) the Rayleigh wave velocity was as low as 45 m/s, and train speeds of only 165–170 km/h were sufficient to observe the effect. In particular, the increase in train speeds from 140 to 180 km/h was accompanied by about tenfold increase in generated ground vibration level, which agrees with the theory. It is now understood that, with the increase of operating train spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ground Vibrations
Ground vibrations is a technical term that is being used to describe mostly man-made vibrations of the ground, in contrast to natural vibrations of the Earth studied by seismology. For example, vibrations caused by explosions, construction works, railway and road transport, etc. - all belong to ground vibrations. General information Ground vibrations are associated with different types of elastic waves propagating through the ground. These are surface waves, mostly Rayleigh waves, and bulk longitudinal waves and transverse waves (or shear waves) propagating into the ground depth. Typical frequency range for environmental ground vibrations is 1 – 200 Hz. Waves of lower frequencies (below 1 Hz) are usually called microseisms, and they are normally associated with natural phenomenae, e.g. water waves in the oceans. Environmental ground vibrations generated by rail and road traffic may cause annoyance to residents of nearby buildings both directly and via generated str ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rayleigh Wave
Rayleigh waves are a type of surface acoustic wave that travel along the surface of solids. They can be produced in materials in many ways, such as by a localized impact or by piezo-electric transduction, and are frequently used in non-destructive testing for detecting defects. Rayleigh waves are part of the seismic waves that are produced on the Earth by earthquakes. When guided in layers they are referred to as Lamb waves, Rayleigh–Lamb waves, or generalized Rayleigh waves. Characteristics Rayleigh waves are a type of surface wave that travel near the surface of solids. Rayleigh waves include both longitudinal and transverse motions that decrease exponentially in amplitude as distance from the surface increases. There is a phase difference between these component motions. The existence of Rayleigh waves was predicted in 1885 by Lord Rayleigh, after whom they were named. In isotropic solids these waves cause the surface particles to move in ellipses in planes normal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swedish High-speed Train X2000 At Ledsgard
Swedish or ' may refer to: Anything from or related to Sweden, a country in Northern Europe. Or, specifically: * Swedish language, a North Germanic language spoken primarily in Sweden and Finland ** Swedish alphabet, the official alphabet used by the Swedish language * Swedish people or Swedes, persons with a Swedish ancestral or ethnic identity ** A national or citizen of Sweden, see demographics of Sweden ** Culture of Sweden * Swedish cuisine See also * * Swedish Church (other) * Swedish Institute (other) * Swedish invasion (other) * Swedish Open (other) Swedish Open is a tennis tournament. Swedish Open may also refer to: *Swedish Open (badminton) The Swedish Open is an open badminton Badminton is a racquet sport played using racquets to hit a shuttlecock across a net. Although it may ... {{disambig Language and nationality disambiguation pages ... [...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. A decibel is the primary unit measurement of sound. "A thunderclap is incredibly loud, producing levels between 100 and 120 dBA ( decibels A)- the equivalent of standing near a jet during take-off." The crack of a supersonic bullet passing overhead or the crack of a bullwhip are examples of a sonic boom in miniature. 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 prohibition of routine supersonic flight overland. Although they cannot be completely prevented, research suggests that with careful shaping of the vehicle, the nuisance due to the sonic booms may be reduced to the point that overland supersonic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supersonic Aircraft
A supersonic aircraft is an aircraft capable of supersonic flight, that is, flying faster than the speed of sound (Mach number 1). Supersonic aircraft were developed in the second half of the twentieth century. Supersonic aircraft have been used for research and military purposes, but only two supersonic aircraft, the Tupolev Tu-144 (first flown on December 31, 1968) and the Concorde (first flown on March 2, 1969), ever entered service for civil use as airliners. Fighter jets are the most common example of supersonic aircraft. The aerodynamics of supersonic flight is called compressible flow because of the compression associated with the shock waves or " sonic boom" created by any object traveling faster than sound. Aircraft flying at speeds above Mach 5 are called hypersonic aircraft. History The first aircraft to fly supersonic in level flight was the American Bell X-1 experimental plane which was powered by a thrust rocket powered by liquid oxygen and ethyl alcoho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X 2000
X 2000, also called SJ X2 or simply as X2, is an electric tilting train operated by SJ in Sweden. It was constructed by Kalmar Verkstad in Kalmar, Sweden (prior to the company being bought by Adtranz in 1996) and launched in 1990 as a first-class only train with a meal included in the ticket price, and free use of the train's fax machine. There is a bistro on board that serves snack bar-style dishes. From 1995 second class was introduced. All trains are equipped with Wi-Fi for passenger access to the Internet and were repainted grey as of 2005. The trains also have electric power supply sockets at all seats in both first and second class. The trains have been fitted with repeaters to improve mobile phone reception. It has a top commercial speed of , but has reached in a test. The reason the X2 was chosen was that Sweden (like most other countries) has very curved railways, and not enough traffic to justify building special high-speed railway lines (at least before 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-speed Trains
High-speed rail (HSR) is a type of rail system that runs significantly faster than traditional rail, using an integrated system of specialised rolling stock and dedicated tracks. While there is no single standard that applies worldwide, lines built to handle speeds above or upgraded lines in excess of are widely considered to be high-speed. The first high-speed rail system, the Tōkaidō Shinkansen, began operations in Japan in 1964 and was widely known as the bullet train. High-speed trains mostly operate on standard gauge tracks of continuously welded rail on grade-separated rights of way with large radii. However, certain regions with wider legacy railways, including Russia and Uzbekistan, have sought to develop a high speed railway network in Russian gauge. There are no narrow gauge high-speed trains; the fastest is the Cape gauge Spirit of Queensland at . Many countries have developed, or are currently building, high-speed rail infrastructure to connect major cities ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rayleigh Waves
Rayleigh waves are a type of surface acoustic wave that travel along the surface of solids. They can be produced in materials in many ways, such as by a localized impact or by piezo-electric transduction, and are frequently used in non-destructive testing for detecting defects. Rayleigh waves are part of the seismic waves that are produced on the Earth by earthquakes. When guided in layers they are referred to as Lamb waves, Rayleigh–Lamb waves, or generalized Rayleigh waves. Characteristics Rayleigh waves are a type of surface wave that travel near the surface of solids. Rayleigh waves include both longitudinal and transverse motions that decrease exponentially in amplitude as distance from the surface increases. There is a phase difference between these component motions. The existence of Rayleigh waves was predicted in 1885 by Lord Rayleigh, after whom they were named. In isotropic solids these waves cause the surface particles to move in ellipses in planes normal to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mach Number
Mach number (M or Ma) (; ) is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound. It is named after the Moravian physicist and philosopher Ernst Mach. : \mathrm = \frac, where: : is the local Mach number, : is the local flow velocity with respect to the boundaries (either internal, such as an object immersed in the flow, or external, like a channel), and : is the speed of sound in the medium, which in air varies with the square root of the thermodynamic temperature. By definition, at Mach1, the local flow velocity is equal to the speed of sound. At Mach0.65, is 65% of the speed of sound (subsonic), and, at Mach1.35, is 35% faster than the speed of sound (supersonic). Pilots of high-altitude aerospace vehicles use flight Mach number to express a vehicle's true airspeed, but the flow field around a vehicle varies in three dimensions, with corresponding variations in local Mach number. The loc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supershear Earthquake
In seismology, a supershear earthquake is an earthquake in which the propagation of the rupture along the fault surface occurs at speeds in excess of the seismic shear wave (S-wave) velocity. This causes an effect analogous to a sonic boom. Rupture propagation velocity During seismic events along a fault surface the displacement initiates at the focus and then propagates outwards. Typically for large earthquakes the focus lies towards one end of the slip surface and much of the propagation is unidirectional (e.g. the 2008 Sichuan and 2004 Indian Ocean earthquakes). Theoretical studies have in the past suggested that the upper bound for propagation velocity is that of Rayleigh waves, approximately 0.92 of the shear wave velocity. However, evidence of propagation at velocities between S-wave and compressional wave (P-wave) values have been reported for several earthquakesArchuleta,R.J. 1984A faulting model for the 1979 Imperial Valley earthquake J. Geophys. Res., 89, 4559–4585. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanical Vibrations
Mechanical may refer to: Machine * Machine (mechanical), a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement * Mechanical calculator, a device used to perform the basic operations of arithmetic * Mechanical energy, the sum of potential energy and kinetic energy * Mechanical system, a system that manages the power of forces and movements to accomplish a task * Mechanism (engineering), a portion of a mechanical device Other * Mechanical (character), one of several characters in Shakespeare's ''A Midsummer Night's Dream'' * A kind of typeface in the VOX-ATypI classification See also * Machine, especially in opposition to an electronic item * ''Mechanical Animals'', the third full-length studio release by Marilyn Manson * Manufactured or artificial, especially in opposition to a biological or natural component * Automation, using machine decisions and processing instead of human * Mechanization, using machine labor in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waves
Waves most often refers to: *Waves, oscillations accompanied by a transfer of energy that travel through space or mass. *Wind waves, surface waves that occur on the free surface of bodies of water. Waves may also refer to: Music *Waves (band) Albums * Waves (Charles Lloyd album), ''Waves'' (Charles Lloyd album) * Waves (Jade Warrior album), ''Waves'' (Jade Warrior album) * Waves (Katrina and the Waves album), ''Waves'' (Katrina and the Waves album) * Waves (Moving Mountains album), ''Waves'' (Moving Mountains album) * Waves (Rachel Platten album), ''Waves'' (Rachel Platten album) * Waves (Rhydian Roberts album), ''Waves'' (Rhydian Roberts album) * Waves (Sam Rivers album), ''Waves'' (Sam Rivers album) * Waves (Story Untold album), ''Waves'' (Story Untold album) * Waves (Terje Rypdal album), ''Waves'' (Terje Rypdal album) * Waves (Waves album), ''Waves'' (Waves album) * ''Waves: Radio 1 Sessions 90–94'', a compilation album by Ride * Waves (EP), ''Waves'' (EP), by Mick Jenkin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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