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Heat-seeking
Infrared homing is a passive weapon guidance system which uses the infrared (IR) light emission from a target to track and follow it seamlessly. Missiles which use infrared seeking are often referred to as "heat-seekers" since infrared is radiated strongly by hot bodies. Many objects such as people, vehicle engines and aircraft generate and emit heat and so are especially visible in the infrared wavelengths of light compared to objects in the background. Infrared seekers are passive devices, which, unlike radar, provide no indication that they are tracking a target. That makes them suitable for sneak attacks during visual encounters or over longer ranges when they are used with a forward looking infrared or similar cuing system. Heat-seekers are extremely effective: 90% of all United States air combat losses over the past 25 years have been caused by infrared-homing missiles. They are, however, subject to a number of simple countermeasures, most notably by dropping flares beh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air-to-air Missile
The newest and the oldest member of Rafael's Python family of AAM for comparisons, Python-5 (displayed lower-front) and Shafrir-1 (upper-back) An air-to-air missile (AAM) is a missile fired from an aircraft for the purpose of destroying another aircraft. AAMs are typically powered by one or more rocket motors, usually solid fueled but sometimes liquid fueled. Ramjet engines, as used on the Meteor, are emerging as propulsion that will enable future medium-range missiles to maintain higher average speed across their engagement envelope. Air-to-air missiles are broadly put in two groups. Those designed to engage opposing aircraft at ranges of less than 16 km are known as short-range or "within visual range" missiles (SRAAMs or WVRAAMs) and are sometimes called "dogfight" missiles because they are designed to optimize their agility rather than range. Most use infrared guidance and are called heat-seeking missiles. In contrast, medium- or long-range missiles (MRAAMs or L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flare
A flare, also sometimes called a fusée, fusee, or bengala in some Latin-speaking countries, is a type of pyrotechnic that produces a bright light or intense heat without an explosion. Flares are used for distress signaling, illumination, or defensive countermeasures in civilian and military applications. Flares may be ground pyrotechnics, projectile pyrotechnics, or parachute-suspended to provide maximum illumination time over a large area. Projectile pyrotechnics may be dropped from aircraft, fired from rocket or artillery, or deployed by flare guns or handheld percussive tubes. History The earliest recorded use of gunpowder for signaling purposes was the 'signal bomb' used by the Chinese Song Dynasty (960–1279) as the Mongol-led Yuan Dynasty (1271–1368) besieged Yangzhou in 1276. These soft-shelled bombs, timed to explode in midair, were used to send messages to a detachment of troops far in the distance. Another mention of the signal bomb appears in a text dating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
US Navy
The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage of its active battle fleet alone exceeding the next 13 navies combined, including 11 allies or partner nations of the United States as of 2015. It has the highest combined battle fleet tonnage (4,635,628 tonnes as of 2019) and the world's largest aircraft carrier fleet, with eleven in service, two new carriers under construction, and five other carriers planned. With 336,978 personnel on active duty and 101,583 in the Ready Reserve, the United States Navy is the third largest of the United States military service branches in terms of personnel. It has 290 deployable combat vessels and more than 2,623 operational aircraft . The United States Navy traces its origins to the Continental Navy, which was established during the American Revolut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timeline Of United States Military Operations
This timeline of United States government military operations, based in part on reports by the Congressional Research Service, shows the years and places in which U.S. military units participated in armed conflicts or occupation of foreign territories. Items in bold are wars most often considered to be ''major conflicts'' by historians and the general public. Note that instances where the U.S. government gave aid alone, with no military personnel involvement, are excluded, as are Central Intelligence Agency operations. In domestic peacetime disputes such as riots and labor issues, only operations undertaken by active duty personnel (aka "federal troops" or "U.S. military") are depicted in this article; state defense forces and the National Guard are not included, as they're not fully integrated into the U.S. armed forces even if they are federalized for duty within the U.S. Extraterritorial and major domestic deployments Portions of this list are from the Congressional Research ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flare (countermeasure)
A flare or decoy flare is an aerial infrared countermeasure used by a plane or helicopter to counter an infrared homing ("heat-seeking") surface-to-air missile or air-to-air missile. Flares are commonly composed of a pyrotechnic composition based on magnesium or another hot-burning metal, with burning temperature equal to or hotter than engine exhaust. The aim is to make the infrared-guided missile seek out the heat signature from the flare rather than the aircraft's engines. Tactics In contrast to radar-guided missiles, IR-guided missiles are very difficult to find as they approach aircraft. They do not emit detectable radar, and they are generally fired from behind, directly toward the engines. In most cases, pilots have to rely on their wingmen to spot the missile's smoke trail and alert of a launch. Since IR-guided missiles have a shorter range than their radar-guided counterparts, good situational awareness of altitude and potential threats continues to be an effective ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface-to-air Missile
A surface-to-air missile (SAM), also known as a ground-to-air missile (GTAM) or surface-to-air guided weapon (SAGW), is a missile designed to be launched from the ground to destroy aircraft or other missiles. It is one type of anti-aircraft system; in modern armed forces, missiles have replaced most other forms of dedicated anti-aircraft weapons, with anti-aircraft guns pushed into specialized roles. The first attempt at SAM development took place during World War II, but no operational systems were introduced. Further development in the 1940s and 1950s led to operational systems being introduced by most major forces during the second half of the 1950s. Smaller systems, suitable for close-range work, evolved through the 1960s and 1970s, to modern systems that are man-portable. Shipborne systems followed the evolution of land-based models, starting with long-range weapons and steadily evolving toward smaller designs to provide a layered defence. This evolution of design increasin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caesium
Caesium (IUPAC spelling) (or cesium in American English) is a chemical element with the symbol Cs and atomic number 55. It is a soft, silvery-golden alkali metal with a melting point of , which makes it one of only five elemental metals that are liquid at or near room temperature. Caesium has physical and chemical properties similar to those of rubidium and potassium. It is pyrophoric and reacts with water even at . It is the least electronegative element, with a value of 0.79 on the Pauling scale. It has only one stable isotope, caesium-133. Caesium is mined mostly from pollucite. The element has 40 known isotopes, making it, along with barium and mercury, one of the elements with the most isotopes. Caesium-137, a fission product, is extracted from waste produced by nuclear reactors. The German chemist Robert Bunsen and physicist Gustav Kirchhoff discovered caesium in 1860 by the newly developed method of flame spectroscopy. The first small-scale applications for caesium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is Earth's most abundant element, and after hydrogen and helium, it is the third-most abundant element in the universe. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula . Diatomic oxygen gas currently constitutes 20.95% of the Earth's atmosphere, though this has changed considerably over long periods of time. Oxygen makes up almost half of the Earth's crust in the form of oxides.Atkins, P.; Jones, L.; Laverman, L. (2016).''Chemical Principles'', 7th edition. Freeman. Many major classes of organic molecules in living organisms contain oxygen atoms, such as proteins, nucleic acids, carbohydrates, and fats, as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silver
Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. The metal is found in the Earth's crust in the pure, free elemental form ("native silver"), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold, lead, and zinc Refining (metallurgy), refining. Silver has long been valued as a precious metal. Silver metal is used in many bullion coins, sometimes bimetallism, alongside gold: while it is more abundant than gold, it is much less abundant as a native metal. Its purity is typically measured on a per-mille basis; a 94%-pure alloy is described as "0.940 fine". As one of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Movietone Sound System
The Movietone sound system is an optical sound-on-film method of recording sound for motion pictures that guarantees synchronization between sound and picture. It achieves this by recording the sound as a variable-density optical track on the same strip of film that records the pictures. The initial version was capable of a frequency response of 8500 Hz. Although sound films today use variable-area tracks, any modern motion picture theater (excluding those that have transitioned to digital cinema) can play a Movietone film without modification to the projector (though if the projector's sound unit has been fitted with red LED or laser light sources, the reproduction quality from a variable density track will be significantly impaired). Movietone was one of four motion picture sound systems under development in the U.S. during the 1920s, the others being DeForest Phonofilm, Warner Brothers' Vitaphone, and RCA Photophone, though Phonofilm was primarily an early version of Movietone. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theodore Case
Theodore Willard Case (December 12, 1888 – May 13, 1944) was an American chemist and inventor known for the invention of the Movietone sound-on-film system. Early life and education Theodore Willard Case was born in 1888 in Auburn, New York to Willard Erastus Case (1857 – 1918) and Eva Fidelia Caldwell Case (1857 – 1952). He attended a few boarding schools as a young man including The Manlius School near Syracuse, New York and Cloyne House School in Newport, Rhode Island He also attended the St. Paul School in Concord, New Hampshire to finish out his secondary education. Following his high school graduation he attended Yale University from 1908 to 1912, where he earned his B.A in Chemistry. He then attended Harvard University where he studied law. He did not find this as fulfilling as pursuing science so he left after about a year. During the years prior to opening the Case Research Lab he worked with his father in laboratories setup in the basements of their fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jagadish Chandra Bose
Sir Jagadish Chandra Bose (;, ; 30 November 1858 – 23 November 1937) was a biologist, physicist, Botany, botanist and an early writer of science fiction. He was a pioneer in the investigation of radio microwave optics, made significant contributions to botany, and was a major force behind the expansion of experimental science on the Indian subcontinent. Bose is considered the father of Bengali science fiction. He invented the crescograph, a device for measuring the growth of plants. Bose (crater), A crater on the moon was named in his honour. He founded Bose Institute, a premier research institute in India and also one of its oldest. Established in 1917, the institute was the first interdisciplinary research centre in Asia. He served as the Director of Bose Institute from its inception until his death. Born in Munshiganj, Bengal Presidency, during British India, British governance of India (now in Bangladesh), Bose graduated from St. Xavier's College, Calcutta (now Kolkata, W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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