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Anechoic Tiles
__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 Sonar#Active sonar, 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 Sonar#Passive sonar, passive sonar. Development in the Third Reich The technology of anechoic tiles was developed by the ''Kriegsmarine'' during the Second World War, Code name, codenamed ''Alberich'' after Alberich, 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 Butyl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HMS Triumph 1 Crop
HMS or hms may refer to: Education * Habib Medical School, of the Islamic University in Uganda * Hartley–Melvin–Sanborn Community School District of Iowa, United States * Harvard Medical School of Harvard University * Heidelberg Middle School, a former American school in Heidelberg, Germany * Hongwanji Mission School, in Hawaii, United States * Horley Methodist School, Teluk Intan, in Malaysia Medicine and science * Hartford Medical Society, an American professional association based in Hartford, Connecticut *Health management system * Hexose monophosphate shunt, an alternative name for the pentose phosphate pathway * Highly migratory species, a classification of fish * Hypermobility spectrum disorder, formerly hypermobility syndrome or HMS * HMS, a brand name of medrysone Technology *Huawei Mobile Services, proprietary apps and services from Huawei bundled with Android devices * HMS Networks, a company in the field of industrial communications * Heavy melting steel * H ... [...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 e ... [...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 or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a power ratio of 101/10 (approximately ) or root-power ratio of 101/20 (approximately ). The strict original usage above only expresses a relative change. However, the word decibel has since also been used for expressing an absolute value that is relative to some fixed reference value, in which case the dB 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 " V" (e.g., "20 dBV"). As it originated from a need to express power ratios, two principal types of scaling of the decibel are used to provide consistency depending on whether the scaling refers to ratios of power quantities or root-power quantities. When expressing a power ratio, it ... [...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 Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet Union, it dissolved in 1991. During its existence, it was the list of countries and dependencies by area, largest country by area, extending across Time in Russia, eleven time zones and sharing Geography of the Soviet Union#Borders and neighbors, borders with twelve countries, and the List of countries and dependencies by population, third-most populous country. An overall successor to the Russian Empire, it was nominally organized as a federal union of Republics of the Soviet Union, national republics, the largest and most populous of which was the Russian SFSR. In practice, Government of the Soviet Union, its government and Economy of the Soviet Union, economy were Soviet-type economic planning, highly centralized. As a one-party state go ... [...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'', a branch of the ''Wehrmacht''. It was officially formed from the ''Marineleitung'' ("Naval Command") of the ''Reichswehr'' on 11 January 1936. In 1937 it was combined with the new '' Seekriegsleitung'' (SKL). There were two re-organisations, in November 1939 and May 1944. It was part of the . 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 ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submarine Hull
A submarine hull has two major components, the ''superstructure'' and the ''pressure hull''. The external portion of a submarine’s hull—that part that does not resist sea pressure and is free-flooding—is known as the “superstructure” in American submarine terminology and the “casing” in British submarine terminology. It is sometimes also referred to as the “light hull” or other descriptive terms. The superstructure (''casing'' in British usage) of a submarine is the outer non-watertight, “free-flooding” hull which provides a hydrodynamically efficient shape. The pressure hull is the inner hull of a submarine that resists sea pressure and maintains the submarine’s structural integrity at (operating) 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 ... [...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, and 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 either ... [...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, 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 List of islands of Denmark, 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 (island), 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 Br ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baltic Sea
The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by the countries of Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden, and the North European Plain, North and Central European Plain regions. It is the world's largest brackish water basin. The sea stretches from 53°N to 66°N latitude and from 10°E to 30°E longitude. It is a Continental shelf#Shelf seas, shelf sea and marginal sea of the Atlantic with limited water exchange between the two, making it an inland sea. 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 (divided into the Bothnian Bay and the Bothnian Sea), 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kiel
Kiel ( ; ) is the capital and most populous city in the northern Germany, German state of Schleswig-Holstein. With a population of around 250,000, it is Germany's largest city on the Baltic Sea. It is located on the Kieler Förde inlet of the Bay of Kiel and lies in the southeast of the Jutland Peninsula, on the mouth of the Schwentine River, approximately northeast of Hamburg. The world's busiest artificial waterway, the Kiel Canal, has a terminus in Kiel's Holtenau district. This canal connects the Baltic to the North Sea, with its other end in Brunsbüttel. Most of Kiel is part of Holstein. The boroughs north of the Schwentine also belong to Wagria, while those north of the Kiel Canal are historically part of Southern Schleswig. Kiel is one of Germany's major maritime centres, known for a variety of international sailing events, including the annual Kiel Week, which is the biggest sailing event in the world. Kiel is also known for the Kiel mutiny, Kiel Mutiny, when sailors re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
