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Anechoic Tile
__NOTOC__ Anechoic tiles are rubber or synthetic polymer tiles containing thousands of tiny voids, applied to the outer hulls of military ships and submarines, as well as anechoic chambers. Their function is twofold: *To absorb the sound waves of active sonar, reducing and distorting the return signal, thereby reducing its effective range. *To attenuate the sounds emitted from the vessel, typically its engines, to reduce the range at which it can be detected by passive sonar. Development in the Third Reich The technology of anechoic tiles was developed by the ''Kriegsmarine'' during the Second World War, codenamed ''Alberich'' after the invisible guardian dwarf of the Rhinegold treasure from Richard Wagner's Der Ring des Nibelungen music dramas. The coating consisted of sheets approximately square and thick, with rows of holes in two sizes, and in diameter. Manufactured by IG Farben as a specially formed synthetic rubber tile and made using a stabilized, non-polar, high ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ASDIC
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on or under the surface of the water, such as other vessels. "Sonar" can refer to one of two types of technology: ''passive'' sonar means listening for the sound made by vessels; ''active'' sonar means emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before the introduction of radar. Sonar may also be used for robot navigation, and SODAR (an upward-looking in-air sonar) is used for atmospheric investigations. The term ''sonar'' is also used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from very low (infrasonic) to extrem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States 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 Revo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decibels
The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a Power, root-power, and field quantities, power or root-power quantity on a logarithmic scale. Two signals whose level (logarithmic quantity), levels differ by one decibel have a power ratio of 101/10 (approximately ) or root-power ratio of 10 (approximately ). The unit expresses a relative change or an absolute value. In the latter case, the numeric value expresses the ratio of a value to a fixed reference value; when used in this way, the unit symbol is often suffixed with letter codes that indicate the reference value. For example, for the reference value of 1 volt, a common suffix is "#Voltage, V" (e.g., "20 dBV"). Two principal types of scaling of the decibel are in common use. When expressing a power ratio, it is defined as ten times the Common logarithm, logarithm in base 10. That is, a change in ''power'' by a factor of 10 corresp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acoustic Signature
The term acoustic signature is used to describe a combination of acoustic emissions of sound emitters, such as those of ships and submarines. In addition, aircraft, machinery, and living animals can be described as having their own characteristic acoustic signatures or sound attributes, which can be used to study their condition, behavior, and physical location. Military use The analysis of acoustic signatures is an important adjunct to passive sonar used to track naval warships and weapons. Similar methods have been used to identify aircraft, especially before the development of sophisticated radar tracking. Sound characteristics The acoustic signature is made up of a number of individual elements. These include: *Machinery noise: noise generated by a ship's engines, propeller shafts, fuel pumps, air conditioning systems, etc. *Cavitation noise: noise generated by the creation of gas bubbles by the turning of a ship's propellers. *Hydrodynamic noise: noise generated by the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national republics; in practice, both its government and its economy were highly centralized until its final years. It was a one-party state governed by the Communist Party of the Soviet Union, with the city of Moscow serving as its capital as well as that of its largest and most populous republic: the Russian SFSR. Other major cities included Leningrad (Russian SFSR), Kiev (Ukrainian SSR), Minsk ( Byelorussian SSR), Tashkent (Uzbek SSR), Alma-Ata (Kazakh SSR), and Novosibirsk (Russian SFSR). It was the largest country in the world, covering over and spanning eleven time zones. The country's roots lay in the October Revolution of 1917, when the Bolsheviks, under the leadership of Vladimir Lenin, overthrew the Russian Provisional Government ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type XXIII
German Type XXIII submarines were the first so-called elektroboote ("electric boats") to become operational. They were small coastal submarines designed to operate in the shallow waters of the North Sea, Black Sea and Mediterranean Sea, where larger Type XXI electric boats were at risk in World War II. They were so small they could carry only two torpedoes, which had to be loaded externally. As with their far larger sisters—the Type XXI—they were able to remain submerged almost all of the time and were faster than conventional U-boats, due to the improved streamlining of their shape, batteries with larger capacity and the snorkel, which allowed the diesel engines to be used while submerged. The Type XXI and XXIII U-boats revolutionized post-war submarine design. Nearly a thousand Type XXIII boats were projected towards the close of World War II, but most of these were either cancelled, scrapped incomplete, or only projected. Background When development began on the Type XXI ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oberkommando Der Marine
The (; abbreviated OKM) was the high command and the highest administrative and command authority of the ''Kriegsmarine''. It was officially formed from the ''Marineleitung'' ("Naval Command") of the ''Reichswehr'' on 11 January 1936. In 1937 it was combined with the newly formed ''Seekriegsleitung'' (SKL). There were two major re-organisations, in November 1939 and May 1944. Organization The OKM was broadly divided into six sections: * At the top was the ''Oberbefehlshaber der Marine'' (OBdM) – the Commander-in-Chief and his staff, with responsibility for liaison with the OKW, and including planning, technical, engineering, medical, economic, research, propaganda and personnel departments. * The ''Seekriegsleitung'' (SKL) ("Naval Warfare Command") was formed on 1 April 1937. Originally closely linked with both the OBdM and the ''Marinekommandoamt'', with the Commander-in-Chief (OBdM) also the Chief of the SKL, and the Chief of the ''Marinekommandoamt'' doubling as the SKL ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submarine Hull
A submarine hull has two major components, the ''light hull'' and the ''pressure hull''. The light hull (''casing'' in British usage) of a submarine is the outer non-watertight hull which provides a hydrodynamically efficient shape. The pressure hull is the inner hull of a submarine that maintains structural integrity with the difference between outside and inside pressure at depth. Shapes Modern submarines are usually cigar-shaped. This design, already visible on very early submarines, is called a "teardrop hull". It is structurally efficient for withstanding external pressure, and significantly reduces the hydrodynamic drag on the sub when submerged, but decreases the sea-keeping capabilities and increases drag while surfaced. History The concept of an outer hydrodynamically streamlined light hull separated from the inner pressure hull was first introduced in the early pioneering submarine Ictineo I designed by the Spanish inventor Narcís Monturiol in 1859. However, whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adhesive
Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advantages over other binding techniques such as sewing, mechanical fastenings, or welding. These include the ability to bind different materials together, the more efficient distribution of stress across a joint, the cost-effectiveness of an easily mechanized process, and greater flexibility in design. Disadvantages of adhesive use include decreased stability at high temperatures, relative weakness in bonding large objects with a small bonding surface area, and greater difficulty in separating objects during testing. Adhesives are typically organized by the method of adhesion followed by ''reactive'' or ''non-reactive'', a term which refers to whether the adhesive chemically reacts in order to harden. Alternatively, they can be organized eithe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Little Belt
The Little Belt (, ) is a strait between the island of Funen and the Jutland Peninsula in Denmark. It is one of the three Danish Straits that drain and connect the Baltic Sea to the Kattegat strait, which drains west to the North Sea and Atlantic Ocean. Geography The Little Belt is about long and to wide, and its deepest point is at Marens Hul west of the island of Fænø, at , which makes it deeper than its sister strait, the Great Belt. Numerous small Danish islands lie within the belt. In part because of its depth, 10% of the water moving between the inner Baltic Sea and the Kattegat flows through the Little Belt. The Little Belt stretches from the town of Juelsminde in the north to the island of Als in the south, with a winding course in between. The northern end is the widest at over . From there it runs southwest, narrowing to about at a place called ''Snævringen'' (The Narrows), where the two Little Belt Bridges are located. South of Fænø, the strait widens to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baltic Sea
The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain. The sea stretches from 53°N to 66°N latitude and from 10°E to 30°E longitude. A marginal sea of the Atlantic, with limited water exchange between the two water bodies, the Baltic Sea drains through the Danish Straits into the Kattegat by way of the Øresund, Great Belt and Little Belt. It includes the Gulf of Bothnia, the Bay of Bothnia, the Gulf of Finland, the Gulf of Riga and the Bay of Gdańsk. The " Baltic Proper" is bordered on its northern edge, at latitude 60°N, by Åland and the Gulf of Bothnia, on its northeastern edge by the Gulf of Finland, on its eastern edge by the Gulf of Riga, and in the west by the Swedish part of the southern Scandinavian Peninsula. The Baltic Sea is connected by artificial waterways to the White Sea via the White Sea–Baltic Canal and to the German ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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