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Gravity Gradiometry
Gravity gradiometry is the study of variations (gravitational anomaly, ''anomalies'') in the Earth's gravity field via measurements of the spatial gradient of gravitational acceleration. The gravity gradient tensor is a 3x3 tensor; it is given in coordinates by the Jacobian matrix of the acceleration vector (g=[g_x g_y g_z]^T), totaling 9 Scalar (physics), scalar quantities: : G=\nabla g = \begin \partial/\partial & \partial/\partial & \partial/\partial\\ \partial/\partial & \partial/\partial & \partial/\partial\\ \partial/\partial & \partial/\partial & \partial/\partial \end It has dimension (physics), dimension of square reciprocal time, in unit of measurement, units of s−2 (or mm−1s−2). Gravity gradiometry is used by oil and mineral prospectors to measure the density of the Bedrock, subsurface, effectively by measuring the rate of change of gravitational acceleration due to underlying rock properties. From this information it is possible to build a picture of subsurface ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mendenhall Gravimeter Pendulums
Mendenhall may refer to: People *Mendenhall (surname) Places United Kingdom *Mendenhall (Minoll), Wiltshire, England United States *Mendenhall Glacier, near Juneau, Alaska *Mendenhall Lake, near Juneau, Alaska *Mendenhall River, near Juneau, Alaska *Mendenhall Valley, near Juneau, Alaska *Mendenhall, Mississippi *Mendenhall, Pennsylvania *Mendenhall Springs, California Other *Mendenhall Observatory, Stillwater, Oklahoma, USA *Mendenhall Order, a decision to change the system of weights and measures to the metric system *Mendenhall Homeplace, a historic 1811 Quaker Homeplace in Jamestown, North Carolina, USA *United States v. Mendenhall, a 1980 decision of the United States Supreme Court See also * Mildenhall (other) {{disambiguation, geo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tidal Acceleration
Tidal acceleration is an effect of the tidal forces between an orbiting natural satellite (e.g. the Moon) and the primary planet that it orbits (e.g. Earth). The acceleration causes a gradual recession of a satellite in a prograde orbit (satellite moving to a higher orbit, away from the primary body, with a lower orbital velocity and hence a longer orbital period), and a corresponding slowdown of the primary's rotation. See supersynchronous orbit. The process eventually leads to ''tidal locking'', usually of the smaller body first, and later the larger body (e.g. theoretically with Earth-Moon system in 50 billion years). The Earth–Moon system is the best-studied case. The similar process of tidal deceleration occurs for satellites that have an orbital period that is shorter than the primary's rotational period, or that orbit in a retrograde direction. These satellites will have a higher and higher orbital velocity and a shorter and shorter orbital period, until a final coll ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superconductivity
Superconductivity is a set of physical properties observed in superconductors: materials where Electrical resistance and conductance, electrical resistance vanishes and Magnetic field, magnetic fields are expelled from the material. Unlike an ordinary metallic Electrical conductor, conductor, whose resistance decreases gradually as its temperature is lowered, even down to near absolute zero, a superconductor has a characteristic Phase transition, critical temperature below which the resistance drops abruptly to zero. An electric current through a loop of superconducting wire can persist indefinitely with no power source. The superconductivity phenomenon was discovered in 1911 by Dutch physicist Heike Kamerlingh Onnes. Like ferromagnetism and Atomic spectral line, atomic spectral lines, superconductivity is a phenomenon which can only be explained by quantum mechanics. It is characterized by the Meissner effect, the complete cancellation of the magnetic field in the interior of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Hunt For Red October (film)
''The Hunt for Red October'' (alternate on-screen Russian title: ''Красный октябрь'') is a 1990 American submarine spy thriller film directed by John McTiernan, produced by Mace Neufeld, and starring Sean Connery, Alec Baldwin, Scott Glenn, James Earl Jones, and Sam Neill. The film is an adaptation of Tom Clancy's 1984 bestselling novel of the same name. It is the first installment of the film series with the protagonist Jack Ryan. The story is set during the late Cold War era and involves a rogue Soviet naval captain who wishes to defect to the United States with his officers and the Soviet Navy's newest and most advanced ballistic missile submarine, a fictional improvement on the Soviet Typhoon-class submarine. A CIA analyst correctly deduces his motive and must prove his theory before a violent confrontation between the Soviet Red Fleet and the United States Navy spirals out of control. The film was a co-production between the motion picture studios P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lockheed Martin
The Lockheed Martin Corporation is an American Arms industry, defense and aerospace manufacturer with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta on March 15, 1995. It is headquartered in North Bethesda, Maryland, United States. As of January 2022, Lockheed Martin employs approximately 121,000 employees worldwide, including about 60,000 engineers and scientists. Reports from 2024 estimate that Lockheed Martin Corporation (LMT) holds a market cap of around $139.7 billion. Lockheed Martin is one of the largest companies in the aerospace, military support, security, and technologies industry. It was the world's largest defense contractor by revenue for fiscal year 2014.POC Top 20 Defence Contractors of 2014 . Retrieved: July 2015 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bell Aerospace
The Bell Aircraft Corporation was an American aircraft manufacturer, a builder of several types of fighter aircraft for World War II but most famous for the Bell X-1, the first supersonic aircraft, and for the development and production of many important civilian and military helicopters. Bell also developed the Reaction Control System for the Mercury Spacecraft, North American X-15, and Bell Rocket Belt. The company was purchased in 1960 by Textron, and lives on as Bell Textron. History As a pilot, Larry Bell saw his first plane at an air show, starting a lifelong fascination with aviation. Bell dropped out of high school in 1912 to join his brother in the burgeoning aircraft industry at the Glenn L. Martin Company, where by 1914 he had become shop superintendent. By 1920, Bell was vice president and general manager of Martin, then based in Cleveland. Feeling that he deserved part ownership, in late 1924, he presented Martin with an ultimatum. Mr. Martin refused, and Bell quit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GOCE
The Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) was the first of European Space Agency, ESA's Living Planet Programme satellite, heavy satellites intended to map in unprecedented detail the Earth's gravity field. The spacecraft's primary instrumentation was a highly sensitive gravity Gravity gradiometry, gradiometer consisting of three pairs of accelerometers which measured gravitational gradients along three orthogonal axes. Launched on 17 March 2009, GOCE mapped the deep structure of the Earth's Mantle (geology), mantle and probed hazardous volcanic regions. It brought new insight into ocean behaviour; this in particular, was a major driver for the mission. By combining the gravity data with information about sea surface height gathered by other satellite altimeters, scientists were able to track the direction and speed of Geostrophic current, geostrophic ocean currents. The low orbit and high accuracy of the system greatly improved the known accuracy and s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kimberlite
Kimberlite is an igneous rock and a rare variant of peridotite. It is most commonly known as the main host matrix for diamonds. It is named after the town of Kimberley, Northern Cape, Kimberley in South Africa, where the discovery of an 83.5-Carat (mass), carat (16.70 g) diamond called the Star of South Africa (diamond), Star of South Africa in 1869 spawned a diamond rush and led to the excavation of the open-pit mine called the Big Hole. Previously, the term kimberlite has been applied to olivine lamproites as Kimberlite II, however this has been in error. Kimberlite occurs in the Earth's Crust (geology), crust in vertical structures known as Volcanic pipe, kimberlite pipes, as well as igneous Dike (geology), dykes and can also occur as horizontal Sill (geology), sills. Kimberlite pipes are the most important source of mined diamonds today. The consensus on kimberlites is that they are formed deep within Earth's mantle. Formation occurs at depths between 150 and 450 kilometres ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reef
A reef is a ridge or shoal of rock, coral, or similar relatively stable material lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic component, abiotic (non-living) processes such as deposition (geology), deposition of sand or wave erosion planning down rock outcrops. However, reefs such as the coral reefs of tropical waters are formed by biotic component, biotic (living) processes, dominated by corals and coralline algae. Artificial reefs, such as shipwrecks and other man-made underwater structures, may occur intentionally or as the result of an accident. These are sometimes designed to increase the physical complexity of featureless sand bottoms to attract a more diverse range of organisms. They provide shelter to various aquatic animals which help prevent extinction. Another reason reefs are put in place is for aquaculture, and fish farmers who are looking to improve their businesses sometimes invest in them. Reefs are often quite n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault (geology)
In geology, a fault is a Fracture (geology), planar fracture or discontinuity in a volume of Rock (geology), rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust (geology), crust result from the action of Plate tectonics, plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction, subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep. A ''fault plane'' is the Plane (geometry), plane that represents the fracture surface of a fault. A ''fault trace'' or ''fault line'' is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geological maps to represent a fault. A ''fault zone'' is a cluster of parallel faults. However, the term is also used for the zone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salt Diapir
A salt dome is a type of structural dome formed when salt (or other evaporite minerals) intrudes into overlying rocks in a process known as diapirism. Salt domes can have unique surface and subsurface structures, and they can be discovered using techniques such as seismic reflection. They are important in petroleum geology as they can function as petroleum traps. Formation Diagram showing formation of salt domes Stratigraphically, salt basins developed periodically from the Proterozoic to the Neogene. The formation of a salt dome begins with the deposition of salt in a restricted basin. In these basins, the outflow of water exceeds inflow. Specifically, the basin loses water through evaporation, resulting in the precipitation and deposition of salt. While the rate of sedimentation of salt is significantly larger than the rate of sedimentation of clastics, it is recognized that a single evaporation event is rarely enough to produce the vast quantities of salt needed to form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
