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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] |
Passive Sonar
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigation, 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Propulsor
{{short description, Mechanical device to propel a vessel A propulsor is a mechanical device that gives propulsion. The word is commonly used in the marine vernacular, and implies a mechanical assembly that is more complicated than a propeller. The Kort nozzle, pump-jet and rim-driven thruster are examples. An example propulsor is shown in the accompanying picture. It has a shroud which cuts down on blade-tip cavitation and radiated noise. It also has a rotor element and a stator. The stator concentrates the thrust in axial direction and reduces energy wasted in the tangential flow (therefore eliminating torque on the hull). The number of blades in the rotor and stator will typically be two different prime numbers to avoid standing waves. The blades in the rotor or the stator may be angled to further reduce noise. The physical design and layout is very much similar to a single stage axial-flow compressor. Other propulsors Voith Schneider The Voith Schneider Propeller, also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submarine Warfare
Submarine warfare is one of the four divisions of underwater warfare, the others being anti-submarine warfare, mine warfare and mine countermeasures. Submarine warfare consists primarily of diesel and nuclear submarines using torpedoes, missiles or nuclear weapons, as well as advanced sensing equipment, to attack other submarines, ships, or land targets. Submarines may also be used for reconnaissance and landing of special forces as well as deterrence. In some navies they may be used for task force screening. The effectiveness of submarine warfare partly depends on the anti-submarine warfare carried out in response. American Civil War The age of submarine warfare began during the American Civil War. The 1860s was a time of many turning points in terms of how naval warfare was fought. Many new types of warships were being developed for use in the United States and Confederate States Navies. Submarine watercraft were among the newly created vessels. The first sinking of an enemy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anti-submarine Warfare
Anti-submarine warfare (ASW, or in older form A/S) is a branch of underwater warfare that uses surface warships, aircraft, submarines, or other platforms, to find, track, and deter, damage, or destroy enemy submarines. Such operations are typically carried out to protect friendly shipping and coastal facilities from submarine attacks and to overcome blockades. Successful ASW operations typically involved a combination of sensor and weapon technologies, along with effective deployment strategies and sufficiently trained personnel. Typically, sophisticated sonar equipment is used for first detecting, then classifying, locating, and tracking a target submarine. Sensors are therefore a key element of ASW. Common weapons for attacking submarines include torpedoes and naval mines, which can both be launched from an array of air, surface, and underwater platforms. ASW capabilities are often considered of significant strategic importance, particularly following provocative instan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type 45 Destroyer
The Type 45 destroyer, also known as the D or ''Daring'' class, is a Ship class, class of six guided-missile destroyers built for the United Kingdom's Royal Navy in the early 21st century. The class is primarily designed for Anti-aircraft warfare, anti-aircraft and anti-missile warfare and is built around the PAAMS (Sea Viper) air-defence system using the SAMPSON Active electronically scanned array (AESA) and the S1850M long-range radars. The first three destroyers were assembled by BAE Systems Surface Fleet Solutions from partially prefabricated "blocks" built at different shipyards; the remaining three were built by BAE Systems Maritime – Naval Ships. The first ship in the ''Daring'' class, HMS Daring (D32), HMS ''Daring'', was launched on 1 February 2006 and commissioned on 23 July 2009. The Type 45 destroyers were built to replace the Type 42 destroyer, Type 42 (''Sheffield''-class) destroyers that had served during the Falklands War, with the last Type 42 being decommissi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stealth Ship
A stealth ship is a ship that employs stealth technology construction techniques in an effort to make it harder to detect by one or more of radar, visual, sonar, and infrared methods. These techniques borrow from stealth aircraft technology, although some aspects such as wake and acoustic signature reduction (acoustic quieting) are unique to stealth ships' design. Although radar cross-section (RCS) reduction is a fairly new concept, many other forms of masking a ship have existed for centuries or even millennia. Shaping In designing a ship with a reduced radar signature, the main concerns are radar beams originating near or slightly above the horizon (as seen from the ship) coming from distant patrol aircraft, other ships, or sea-skimming anti-ship missiles with active radar seekers. Therefore, the shape of the ship avoids vertical surfaces, which are effective at reflecting such beams directly back to the emitter. Retro-reflective right angles are eliminated to avoid the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Underwater Acoustics
Underwater acoustics is the study of the propagation of sound in water and the interaction of the mechanical waves that constitute sound with the water, its contents and its boundaries. The water may be in the ocean, a lake, a river or a tank. Typical frequencies associated with underwater acoustics are between 10 Hz and 1 MHz. The propagation of sound in the ocean at frequencies lower than 10 Hz is usually not possible without penetrating deep into the seabed, whereas frequencies above 1 MHz are rarely used because they are absorbed very quickly. Underwater acoustics is sometimes known as hydroacoustics. The field of underwater acoustics is closely related to a number of other fields of acoustic study, including sonar, transduction, signal processing, acoustical oceanography, bioacoustics, and physical acoustics. History Underwater sound has probably been used by marine animals for millions of years. The science of underwater acoustics began in 1490, when Leonardo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sonar
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigation, 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RV Triton
The Research Vessel ''Triton'' is a trimaran vessel owned by Gardline Marine Sciences Limited and a former prototype British warship demonstrator for the UK's Defence Evaluation and Research Agency (later QinetiQ). She was built as a technology demonstrator ship for the Royal Navy's Future Surface Combatant, and has been used to both prove the viability of the hull-form and as a trials platform for other QinetiQ innovations. The ship was used by the Australian Border Force's Marine Unit, and was for a time moored in the River Fal near the King Harry chain ferry. Up until July 2019 she was moored on the River Yare, Great Yarmouth in Norfolk, England. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Future Surface Combatant (Royal Navy)
The Type 26 frigate or City-class frigate is a class of frigate being built for the United Kingdom's Royal Navy, with variants also being built for the Australian and Canadian navies. The programme, known as the Global Combat Ship, was launched by the UK Ministry of Defence to partially replace the navy's thirteen Type 23 frigates, and for export. Its primary role is to conduct advanced anti-submarine warfare missions while supporting air defence and general purpose operations. The type is the first naval platform shared between Australia, Canada and the United Kingdom since the Tribal-class destroyer. The programme began in 1998, under what was then known as the Future Surface Combatant (FSC). However, by March 2010, this procurement programme had evolved to become the Global Combat Ship, following the announcement of a four-year, £127 million design contract being awarded to BAE Systems Maritime – Naval Ships. The design passed Main Gate 1 in early 2015, with the Demonstra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trimaran
A trimaran (or double-outrigger) is a multihull boat that comprises a main hull and two smaller outrigger hulls (or "floats") which are attached to the main hull with lateral beams. Most modern trimarans are sailing yachts designed for recreation or racing; others are ferries or warships. They originated from the traditional double-outrigger hulls of the Austronesian cultures of Maritime Southeast Asia; particularly in the Philippines and Eastern Indonesia, where it remains the dominant hull design of traditional fishing boats. Double-outriggers are derived from the older catamaran and single-outrigger boat designs. Terminology The word "trimaran" is a portmanteau of "tri" and "(cata)maran", a term that is thought to have been coined by Victor Tchetchet, a pioneering, Ukrainian-born modern multihull designer. Trimarans consist of a main hull connected to outrigger floats on either side by a crossbeam, wing, or other form of superstructure—the traditional Polynesian terms f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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