|
Gruppenhorchgerät
The ''Gruppenhorchgerät'' ('group listening device', abbreviated GHG) was a hydrophone array which was used on vessels of the German Kriegsmarine in World War II. Development In World War I carbon microphones were still used as sound receivers. The individual receivers were mostly placed in the front part of the vessel along the hull sides to have enough distance from the screw and the noise they emitted. The individual microphones were arranged in groups and each was oriented in a different direction. The individual microphones had to be connected manually to take bearings. They were not very reliable, so other transducers were experimented with. Dynamic microphones were also discarded. At the end of the process, the piezoelectric principle was deemed the most suitable. This was discovered by Pierre Curie in 1880. The quartz crystals generate electric voltage depending on the pressure acting on it. In collaboration with the Imperial German Navy, Atlas Werke AG in Bremen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
U-boat
U-boats are Submarine#Military, naval submarines operated by Germany, including during the World War I, First and Second World Wars. The term is an Anglicization#Loanwords, anglicized form of the German word , a shortening of (), though the German term refers to any submarine. Austro-Hungarian Navy submarines were also known as U-boats. U-boats are most known for their unrestricted submarine warfare in both world wars, trying to Commerce raiding, disrupt merchant traffic towards the UK and force the UK out of the war. In World War I, Germany intermittently waged unrestricted submarine warfare against the United Kingdom, UK: a first campaign in 1915 was abandoned after strong protests from the US but in 1917 the Germans, facing deadlock on the continent, saw no other option than to resume the campaign in February 1917. The renewed campaign failed to achieve its goal mainly because of the introduction of Convoys in World War I, convoys. Instead the campaign ensured final defeat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
U-boats
U-boats are naval submarines operated by Germany, including during the First and Second World Wars. The term is an anglicized form of the German word , a shortening of (), though the German term refers to any submarine. Austro-Hungarian Navy submarines were also known as U-boats. U-boats are most known for their unrestricted submarine warfare in both world wars, trying to disrupt merchant traffic towards the UK and force the UK out of the war. In World War I, Germany intermittently waged unrestricted submarine warfare against the UK: a first campaign in 1915 was abandoned after strong protests from the US but in 1917 the Germans, facing deadlock on the continent, saw no other option than to resume the campaign in February 1917. The renewed campaign failed to achieve its goal mainly because of the introduction of convoys. Instead the campaign ensured final defeat as the campaign was a contributing factor to the entry of the US in the First World War. In World War II, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrophone
A hydrophone () is a microphone designed for underwater use, for recording or listening to underwater sound. Most hydrophones contains a piezoelectric transducer that generates an electric potential when subjected to a pressure change, such as a sound wave. A hydrophone can also detect airborne sounds but is insensitive of them because it is designed to match the acoustic impedance of water, a denser fluid than air. Sound travels 4.3 times faster in water than in air, and a sound wave in water exerts a pressure 60 times more than what is exerted by a wave of the same amplitude in air. Similarly, a standard microphone can be buried in the ground, or immersed in water if it is put in a waterproof container but will give poor performance because of the similarly-bad acoustic impedance match. History The first hydrophones consisted of a tube with a thin membrane covering the submerged end and the observer's ear of the equipment. The design of effective hydrophones must take into a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World War II German Electronics
The world is the totality of entities, the whole of reality, or everything that Existence, exists. The nature of the world has been conceptualized differently in different fields. Some conceptions see the world as unique, while others talk of a "plurality of worlds". Some treat the world as #Monism and pluralism, one simple object, while others analyze the world as a complex made up of parts. In #Scientific cosmology, scientific cosmology, the world or universe is commonly defined as "the totality of all space and time; all that is, has been, and will be". #Theories of modality, Theories of modality talk of possible worlds as complete and consistent ways how things could have been. #Phenomenology, Phenomenology, starting from the horizon of co-given objects present in the periphery of every experience, defines the world as the biggest horizon, or the "horizon of all horizons". In #Philosophy of mind, philosophy of mind, the world is contrasted with the mind as that which is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microphones
A microphone, colloquially called a mic (), or mike, is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public events, motion picture production, live and recorded audio engineering, sound recording, two-way radios, megaphones, and radio and television broadcasting. They are also used in computers and other electronic devices, such as mobile phones, for recording sounds, speech recognition, VoIP, and other purposes, such as ultrasonic sensors or knock sensors. Several types of microphone are used today, which employ different methods to convert the air pressure variations of a sound wave to an electrical signal. The most common are the dynamic microphone, which uses a coil of wire suspended in a magnetic field; the condenser microphone, which uses the vibrating Diaphragm (acoustics), diaphragm as a capacitor plate; and the contact microphone, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capital Ship
The capital ships of a navy are its most important warships; they are generally the larger ships when compared to other warships in their respective fleet. A capital ship is generally a leading or a primary ship in a naval fleet. Strategic implications There is usually no formal criterion for the classification, but it is a useful concept in naval strategy; for example, it permits comparisons between relative naval strengths in a theatre of operations without the need for considering specific details of tonnage or gun diameters. A notable example of this is the Alfred Thayer Mahan, Mahanian doctrine, which was applied in the Sinking of Prince of Wales and Repulse, planning of the defence of Singapore in World War II, where the Royal Navy had to decide the allocation of its battleships and battlecruisers between the Atlantic and Pacific theatres. The Mahanian doctrine was also applied by the Imperial Japanese Navy, leading to its Preventive war, preventive move to Attack on P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type XXI Submarine
Type XXI submarines were a class of German diesel–electric '' Elektroboot'' (German: "electric boat") submarines designed during the Second World War. One hundred eighteen were completed, with four being combat-ready. During the war only two were put into active service and went on patrols, but these were not used in combat. They were the first submarines designed to operate primarily submerged, rather than spending most of their time as surface ships that could submerge for brief periods as a means of escaping detection. They incorporated many batteries to increase the time they could spend submerged, to as much as several days, and they only needed to surface to periscope depth for recharging via a snorkel. The design included many general improvements as well: much greater underwater speed by an improved hull design, greatly improved diving times, power-assisted torpedo reloading and greatly improved crew accommodations. However, the design was also flawed in many ways, wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type VII Submarine
Type VII U-boats were the most common type of Nazi Germany, German World War II U-boat. 704 boats were built by the end of the war. The type had several modifications. The Type VII was the most numerous U-boat type to be involved in the Battle of the Atlantic. The lone surviving example, , is on display at the Laboe Naval Memorial located in Laboe, Schleswig-Holstein, Germany. At the start of the Second World War the ''Type VII'' class wastogether with the British British U-class submarine, ''U'', British S-class submarine (1931), ''S'' and British T-class submarine, ''T'' class and Dutch O 21-class submarine, ''O 21'' classone of the most advanced submarine classes in service. Design After the defeat in World War I, the Treaty of Versailles forbade Germany to build submarines. Germany circumvented the treaty by setting up the Netherlands, Dutch dummy company ''NV Ingenieurskantoor voor Scheepsbouw Den Haag'' (I.v.S) which continued to design submarines. Based on the World Wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Navy
The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom of England, English and Kingdom of Scotland, Scottish kings from the early Middle Ages, medieval period, the first major maritime engagements were fought in the Hundred Years' War against Kingdom of France, France. The modern Royal Navy traces its origins to the English Navy of the early 16th century; the oldest of the British Armed Forces, UK's armed services, it is consequently known as the Senior Service. From the early 18th century until the World War II, Second World War, it was the world's most powerful navy. The Royal Navy played a key part in establishing and defending the British Empire, and four Imperial fortress colonies and a string of imperial bases and coaling stations secured the Royal Navy's ability to assert naval superior ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrostriction
In electromagnetism, electrostriction is a property of all electrical non- conductor or dielectrics. Electrostriction causes these materials to change their shape under the application of an electric field. It is the dual property to magnetostriction. Explanation Electrostriction is a property of all dielectric materials, and is caused by displacement of ions in the crystal lattice upon being exposed to an external electric field. The cause of electrostrictive is linked to anharmonic effects. Positive ions will be displaced in the direction of the field, while negative ions will be displaced in the opposite direction. This displacement will accumulate throughout the bulk material and result in an overall strain (elongation) in the direction of the field. The thickness will be reduced in the orthogonal directions characterized by Poisson's ratio. All insulating materials consisting of more than one type of atom will be ionic to some extent due to the difference of electronegativ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phased Array
In antenna (radio), antenna theory, a phased array usually means an electronically scanned array, a computer-controlled Antenna array, array of antennas which creates a radio beam, beam of radio waves that can be electronically steered to point in different directions without moving the antennas. In a phased array, the power from the transmitter is fed to the radiating elements through devices called ''phase shifters'', controlled by a computer system, which can alter the phase or signal delay electronically, thus steering the beam of radio waves to a different direction. Since the size of an antenna array must extend many wavelengths to achieve the high gain needed for narrow beamwidth, phased arrays are mainly practical at the high frequency end of the radio spectrum, in the ultrahigh frequency, UHF and microwave bands, in which the operating wavelengths are conveniently small. Phased arrays were originally invented for use in military radar systems, to detect fast moving pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
