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Demagnetizing
Degaussing is the process of decreasing or eliminating a remnant magnetic field. It is named after the gauss, a unit of magnetism, which in turn was named after Carl Friedrich Gauss. Due to magnetic hysteresis, it is generally not possible to reduce a magnetic field completely to zero, so degaussing typically induces a very small "known" field referred to as bias. Degaussing was originally applied to reduce ships' magnetic signatures during World War II. Degaussing is also used to reduce magnetic fields in cathode ray tube monitors and to destroy data held on magnetic storage. Ships' hulls The term was first used by then-Commander Charles F. Goodeve, Royal Canadian Naval Volunteer Reserve, during World War II while trying to counter the German magnetic naval mines that were wreaking havoc on the British fleet. The mines detected the increase in the magnetic field when the steel in a ship concentrated the Earth's magnetic field over it. Admiralty scientists, including Go ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Hysteresis
Magnetic hysteresis occurs when an external magnetic field is applied to a ferromagnet such as iron and the atomic dipoles align themselves with it. Even when the field is removed, part of the alignment will be retained: the material has become ''magnetized''. Once magnetized, the magnet will stay magnetized indefinitely. To demagnetize it requires heat or a magnetic field in the opposite direction. This is the effect that provides the element of memory in a hard disk drive. The relationship between field strength and magnetization is not linear in such materials. If a magnet is demagnetized () and the relationship between and is plotted for increasing levels of field strength, follows the ''initial magnetization curve''. This curve increases rapidly at first and then approaches an asymptote called magnetic saturation. If the magnetic field is now reduced monotonically, follows a different curve. At zero field strength, the magnetization is offset from the origin by an a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathode Ray Tube
A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms ( oscilloscope), pictures ( television set, computer monitor), radar targets, or other phenomena. A CRT on a television set is commonly called a picture tube. CRTs have also been used as memory devices, in which case the screen is not intended to be visible to an observer. The term '' cathode ray'' was used to describe electron beams when they were first discovered, before it was understood that what was emitted from the cathode was a beam of electrons. In CRT television sets and computer monitors, the entire front area of the tube is scanned repeatedly and systematically in a fixed pattern called a raster. In color devices, an image is produced by controlling the intensity of each of three electron beams, one for each additive primary color (red, gre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. A permanent magnet's magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets. In addition, a nonuniform magnetic field exerts minuscule forces on "nonmagnetic" materials by three other magnetic effects: paramagnetism, diamagnetism, and antiferromagnetism, although these forces are usually so small they can only be detected by laboratory equipment. Magnetic fields surround magnetized materials, and are created by electric currents such as those used in electromagnets, and by electric fields varying in time. Since both strength and direction of a magnetic field may vary with location, it is described mathematically by a function assigning a vector to each point of space ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cruiser
A cruiser is a type of warship. Modern cruisers are generally the largest ships in a fleet after aircraft carriers and amphibious assault ships, and can usually perform several roles. The term "cruiser", which has been in use for several hundred years, has changed its meaning over time. During the Age of Sail, the term ''cruising'' referred to certain kinds of missions—independent scouting, commerce protection, or raiding—fulfilled by frigates or sloops-of-war, which functioned as the ''cruising warships'' of a fleet. In the middle of the 19th century, ''cruiser'' came to be a classification of the ships intended for cruising distant waters, for commerce raiding, and for scouting for the battle fleet. Cruisers came in a wide variety of sizes, from the medium-sized protected cruiser to large armored cruisers that were nearly as big (although not as powerful or as well-armored) as a pre-dreadnought battleship. With the advent of the dreadnought battleship before ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Naval Station Norfolk
Naval Station Norfolk is a United States Navy base in Norfolk, Virginia, that is the headquarters and home port of the U.S. Navy's Fleet Forces Command. The installation occupies about of waterfront space and of pier and wharf space of the Hampton Roads peninsula known as Sewell's Point. It is the world's largest naval station, with the largest concentration of U.S. Navy forces through 75 ships alongside 14 piers and with 134 aircraft and 11 aircraft hangars at the adjacently operated Chambers Field. Port Services controls more than 3,100 ships' movements annually as they arrive and depart their berths. Air Operations conducts over 100,000 flight operations each year, an average of 275 flights per day or one every six minutes. Over 150,000 passengers and 264,000 tons of mail and cargo depart annually on Air Mobility Command (AMC) aircraft and other AMC-chartered flights from the airfield's AMC Terminal. History The area where the base is located was the site of the original 19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lambert's Point Deperming Station
Lambert's Point Deperming Station is a United States Navy deperming facility located in the Elizabeth River just off Lambert's Point, Norfolk, Virginia, United States. It was built in the mid-1940s and services the U.S. Atlantic Fleet. The station, which is administered by Naval Station Norfolk, consists of two parallel pile-supported piers, roughly 1140 ft. (345 m.) in length, which form a slip that can accommodate all Navy and Coast Guard A coast guard or coastguard is a maritime security organization of a particular country. The term embraces wide range of responsibilities in different countries, from being a heavily armed military force with customs and security duties to ... ships up to and including the largest warships afloat, the ''Nimitz'' class aircraft carriers. There is a second pier for smaller vessels and support craft. The station has administrative offices and a medical clinic on site. When viewed from the air, the pier configuration resembles the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Navy
A navy, naval force, or maritime force is the branch of a nation's armed forces principally designated for naval and amphibious warfare; namely, lake-borne, riverine, littoral, or ocean-borne combat operations and related functions. It includes anything conducted by surface ships, amphibious ships, submarines, and seaborne aviation, as well as ancillary support, communications, training, and other fields. The strategic offensive role of a navy is projection of force into areas beyond a country's shores (for example, to protect sea-lanes, deter or confront piracy, ferry troops, or attack other navies, ports, or shore installations). The strategic defensive purpose of a navy is to frustrate seaborne projection-of-force by enemies. The strategic task of the navy also may incorporate nuclear deterrence by use of submarine-launched ballistic missiles. Naval operations can be broadly divided between riverine and littoral applications ( brown-water navy), open-ocean applicat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Anomaly Detector
A magnetic anomaly detector (MAD) is an instrument used to detect minute variations in the Earth's magnetic field. The term refers specifically to magnetometers used by military forces to detect submarines (a mass of ferromagnetic material creates a detectable disturbance in the magnetic field); military MAD equipment is a descendant of geomagnetic survey or aeromagnetic survey instruments used to search for minerals by detecting their disturbance of the normal earth-field. History Geoexploration by measuring and studying variations in the Earth's magnetic field has been conducted by scientists since 1843. The first uses of magnetometers were for the location of ore deposits. Thalen's "The Examination of Iron Ore Deposits by Magnetic Measurements", published in 1879, was the first scientific treatise describing this practical use. Magnetic anomaly detectors employed to detect submarines during World War II harnessed the fluxgate magnetometer, an inexpensive and easy to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-temperature Superconductivity
High-temperature superconductors (abbreviated high-c or HTS) are defined as materials that behave as superconductors at temperatures above , the boiling point of liquid nitrogen. The adjective "high temperature" is only in respect to previously known superconductors, which function at even colder temperatures close to absolute zero. In absolute terms, these "high temperatures" are still far below ambient, and therefore require cooling. The first high-temperature superconductor was discovered in 1986, by IBM researchers Johannes Georg Bednorz, Bednorz and Karl Alexander Müller, Müller, who were awarded the Nobel Prize in Physics in 1987 "for their important break-through in the discovery of superconductivity in ceramic materials". Most high-c materials are type-II superconductors. The major advantage of high-temperature superconductors is that they can be cooled by using liquid nitrogen, as opposed to the previously known superconductors which require expensive and hard-to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Proximity Fuze
A magnetic proximity fuse was patented by P.J. Eliomarkakis, (United States Patent US2434551 of January 13, 1948) although similar devices had been in service for nearly a decade. It is a type of proximity fuze that initiates a detonator in a piece of ordnance such as a land mine, naval mine, depth charge, or shell when the fuse's magnetic equilibrium is upset by a magnetic object such as a tank or a submarine. Magnetic field sensors and movement sensors inside the ordnance detect changes to the terrestrial magnetic field of the ordnance caused by another ferromagnetic object. A signal processor inside the ordnance receives the signals from the magnetic field sensors and movement sensors and activates the detonator which will then detonate the explosives within the ordnance. Examples Examples of pieces of ordnance that employ a magnetic fuze include: * the Chinese Chen-2 bottom mine * the Egyptian T-93 mine See also * Proximity sensor * Reed switch * Precision bombing * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
USS Deperm (ADG-10)
USS ''Deperm'' (ADG-10) was a degaussing vessel of the United States Navy, named after the term '' deperm'', a procedure for erasing the permanent magnetism from ships and submarines to camouflage them against magnetic detection vessels and enemy marine mines. Originally planned as a patrol craft escort The ''PCE-842''-class patrol craft were United States Navy patrol craft escorts designed during World War II that were intended for coastal and convoy escort. The design was derived from the as a substitute for the s that were used for anti-su ... (PCE-883), she was laid down in 1943, launched in 1944, and commissioned in 1945. She was subsequently redesignated a degaussing vessel, YDG-10, and named ''Deperm''. Struck from the Naval Register 21 February 1975, ''Deperm'' was sunk as a target 22 September 1982 at . According to the available depth data in 2020, at this location the bottom is between 1250m and 1500m along the edge of a basin. References * Shipwrecks of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Auxiliaries Of The United States Navy
This is a list of auxiliaries of the United States Navy. It covers the various types of ships that support the frontline combat vessels of the United States Navy. Ship status is indicated as either currently active (including ready reserve), inactive or precommissioning Ships in the inactive category include only ships in the inactive reserve, ships which have been disposed from US service have no listed status. Ships in the precommissioning category include ships under construction or on order. Crane Ships (AB) * USS ''Kearsarge'' (AB-1), ex-BB-5 Colliers (AC) * USS ''Hannibal'' (1898) * USS ''Justin'' (1898) * USS ''Leonidas'' (1898) * USS ''Marcellus'' (1879) * USS ''Merrimac'' (1898) * USS ''Quincy'' (1918) * USS ''Saturn'' (1898) * USS ''Southery'' (1898) * USS ''Sterling'' (1898) * USS ''Vestal'' (AC-1), later AR-4 * USS ''Ontario'' (AC-2), later AR-3 * USS ''Jupiter'' (AC-3), later CV-1, AV-3 * USS ''Cyclops'' (AC-4), lost March 1918 * USS ''Vulcan' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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