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Carl Emil Krarup
Carl Emil Krarup (12 October 1872 – 29/30 December 1909) was a Danish telegraph engineer who is chiefly known for the invention of a kind of loaded cable, eponymously called Krarup cable, which made improvements in the transmission of telephone signals, especially on submarine cables. Career Krarup was originally a civil engineer. He was in charge of public works in Copenhagen until 1898 when he joined the Danish Telegraph Administration. In 1901 he conducted research at the University of Würzburg in Germany on loaded lines. Returning to Denmark he continued the theoretical work at the University of Copenhagen and published a paper in 1902.Huurdeman, p. 321. Krarup cable Krarup cable is a method of loading lines to reduce their distortion. All methods of loading add series inductance to the cable to try to meet the Heaviside condition for no signal distortion. Krarup cable consists of iron wires wound tightly around the copper conducting cores and it is the iron that is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loading Coil
A loading coil or load coil is an inductor that is inserted into an electronic circuit to increase its inductance. The term originated in the 19th century for inductors used to prevent signal distortion in long-distance telegraph transmission cables. The term is also used for inductors in radio antennas, or between the antenna and its feedline, to make an electrically short antenna resonant at its operating frequency. The concept of loading coils was discovered by Oliver Heaviside in studying the problem of slow signalling speed of the first transatlantic telegraph cable in the 1860s. He concluded additional inductance was required to prevent amplitude and time delay distortion of the transmitted signal. The mathematical condition for distortion-free transmission is known as the Heaviside condition. Previous telegraph lines were overland or shorter and hence had less delay, and the need for extra inductance was not as great. Submarine communications cables are particularly sub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submarine Communications Cable
A submarine communications cable is a cable laid on the sea bed between land-based stations to carry telecommunication signals across stretches of ocean and sea. The first submarine communications cables laid beginning in the 1850s carried telegraphy traffic, establishing the first instant telecommunications links between continents, such as the first transatlantic telegraph cable which became operational on 16 August 1858. Subsequent generations of cables carried telephone traffic, then data communications traffic. Modern cables use optical fibre technology to carry digital data, which includes telephone, Internet and private data traffic. Modern cables are typically about in diameter and weigh around for the deep-sea sections which comprise the majority of the run, although larger and heavier cables are used for shallow-water sections near shore. Submarine cables first connected all the world's continents (except Antarctica) when Java was connected to Darwin, Northern Terr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Würzburg
The Julius Maximilian University of Würzburg (also referred to as the University of Würzburg, in German ''Julius-Maximilians-Universität Würzburg'') is a public research university in Würzburg, Germany. The University of Würzburg is one of the oldest institutions of higher learning in Germany, having been founded in 1402. The university initially had a brief run and was closed in 1415. It was reopened in 1582 on the initiative of Julius Echter von Mespelbrunn. Today, the university is named for Julius Echter von Mespelbrunn and Maximilian Joseph. The University of Würzburg is part of the U15 group of research-intensive German universities. The university is also a member of the Coimbra Group. Name Its official name is Julius-Maximilians-Universität Würzburg (or "Julius-Maximilian University of Würzburg") but it is commonly referred to as the University of Würzburg. This name is taken from Julius Echter von Mespelbrunn, Prince-Bishop of Würzburg, who reestablishe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Copenhagen
The University of Copenhagen ( da, Københavns Universitet, KU) is a prestigious public university, public research university in Copenhagen, Copenhagen, Denmark. Founded in 1479, the University of Copenhagen is the second-oldest university in Scandinavia after Uppsala University, and ranks as one of the top universities in the Nordic countries, Europe and the world. Its establishment sanctioned by Pope Sixtus IV, the University of Copenhagen was founded by Christian I of Denmark as a Catholic teaching institution with a predominantly Theology, theological focus. In 1537, it was re-established by King Christian III as part of the Lutheran Reformation. Up until the 18th century, the university was primarily concerned with educating clergymen. Through various reforms in the 18th and 19th century, the University of Copenhagen was transformed into a modern, Secularism, secular university, with science and the humanities replacing theology as the main subjects studied and taught. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inductance
Inductance is the tendency of an electrical conductor to oppose a change in the electric current flowing through it. The flow of electric current creates a magnetic field around the conductor. The field strength depends on the magnitude of the current, and follows any changes in current. From Faraday's law of induction, any change in magnetic field through a circuit induces an electromotive force (EMF) (voltage) in the conductors, a process known as electromagnetic induction. This induced voltage created by the changing current has the effect of opposing the change in current. This is stated by Lenz's law, and the voltage is called ''back EMF''. Inductance is defined as the ratio of the induced voltage to the rate of change of current causing it. It is a proportionality factor that depends on the geometry of circuit conductors and the magnetic permeability of nearby materials. An electronic component designed to add inductance to a circuit is called an inductor. It typically ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heaviside Condition
The Heaviside condition, named for Oliver Heaviside (1850–1925), is the condition an electrical transmission line must meet in order for there to be no distortion of a transmitted signal. Also known as the distortionless condition, it can be used to improve the performance of a transmission line by adding loading to the cable. The condition A transmission line can be represented as a distributed-element model of its primary line constants as shown in the figure. The primary constants are the electrical properties of the cable per unit length and are: capacitance ''C'' (in farads per meter), inductance ''L'' (in henries per meter), series resistance ''R'' (in ohms per meter), and shunt conductance ''G'' (in siemens per meter). The series resistance and shunt conductivity cause losses in the line; for an ideal transmission line, \scriptstyle R=G=0. The Heaviside condition is satisfied when :\frac = \frac. This condition is for no distortion, but not for no loss. Back ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permalloy
Permalloy is a nickel–iron magnetic alloy, with about 80% nickel and 20% iron content. Invented in 1914 by physicist Gustav Elmen at Bell Telephone Laboratories, it is notable for its very high magnetic permeability, which makes it useful as a magnetic core material in electrical and electronic equipment, and also in magnetic shielding to block magnetic fields. Commercial permalloy alloys typically have relative permeability of around 100,000, compared to several thousand for ordinary steel. In addition to high permeability, its other magnetic properties are low coercivity, near zero magnetostriction, and significant anisotropic magnetoresistance. The low magnetostriction is critical for industrial applications, allowing it to be used in thin films where variable stresses would otherwise cause a ruinously large variation in magnetic properties. Permalloy's electrical resistivity can vary as much as 5% depending on the strength and the direction of an applied magnetic field. P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helsingør
Helsingør ( , ; sv, Helsingör), classically known in English as Elsinore ( ), is a city in eastern Denmark. Helsingør Municipality had a population of 62,686 on 1 January 2018. Helsingør and Helsingborg in Sweden together form the northern reaches of the Øresund Region, centered on Copenhagen and Malmö. The HH Ferry route connects Helsingør with Helsingborg, 4 km (2.5 miles) across the Øresund. It is known for its castle Kronborg, which William Shakespeare presumably had in mind for his play ''Hamlet.'' History The name ''Helsingør'' has been believed to be derived from the word ''hals'' meaning "neck" or "narrow strait," referring to the narrowest point of the ''Øresund'' (Øre Sound) between what is now Helsingør and Helsingborg, Sweden. The people were mentioned as ''Helsinger'' (which may mean "the people of the strait") for the first time in King Valdemar the Victorious's ''Liber Census Daniæ'' from 1231 (not to be confused with the Helsings of Hä ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helsingborg
Helsingborg (, , , ) is a city and the seat of Helsingborg Municipality, Scania (Skåne), Sweden. It is the second-largest city in Scania (after Malmö) and ninth-largest in Sweden, with a population of 113,816 (2020). Helsingborg is the central urban area of northwestern Scania and Sweden's closest point to Denmark: the Danish city Helsingør is clearly visible about to the west on the other side of the Øresund. The HH Ferry route across the sound has more than 70 car ferry departures from each harbour every day. Historic Helsingborg, with its many old buildings, is a scenic coastal city. The buildings are a blend of old-style stone-built churches and a 600-year-old medieval fortress (Kärnan) in the city centre, and more modern commercial buildings. The streets vary from wide avenues to small alley-ways. ''Kullagatan'', the main pedestrian shopping street in the city, was the first pedestrian shopping street in Sweden. History Helsingborg is one of the oldest cities of wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Danish Engineers
Danish may refer to: * Something of, from, or related to the country of Denmark People * A national or citizen of Denmark, also called a "Dane," see Demographics of Denmark * Culture of Denmark * Danish people or Danes, people with a Danish ancestral or ethnic identity * A member of the Danes, a Germanic tribe * Danish (name), a male given name and surname Language * Danish language, a North Germanic language used mostly in Denmark and Northern Germany * Danish tongue or Old Norse, the parent language of all North Germanic languages Food * Danish cuisine * Danish pastry, often simply called a "Danish" See also * Dane (other) * * Gdańsk Gdańsk ( , also ; ; csb, Gduńsk;Stefan Ramułt, ''Słownik języka pomorskiego, czyli kaszubskiego'', Kraków 1893, Gdańsk 2003, ISBN 83-87408-64-6. , Johann Georg Theodor Grässe, ''Orbis latinus oder Verzeichniss der lateinischen Benen ... * List of Danes * Languages of Denmark {{disambiguation Language and n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1872 Births
Year 187 ( CLXXXVII) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Quintius and Aelianus (or, less frequently, year 940 '' Ab urbe condita''). The denomination 187 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. Events By place Roman Empire * Septimius Severus marries Julia Domna (age 17), a Syrian princess, at Lugdunum (modern-day Lyon). She is the youngest daughter of high-priest Julius Bassianus – a descendant of the Royal House of Emesa. Her elder sister is Julia Maesa. * Clodius Albinus defeats the Chatti, a highly organized German tribe that controlled the area that includes the Black Forest. By topic Religion * Olympianus succeeds Pertinax as bishop of Byzantium (until 198). Births * Cao Pi, Chinese emperor of the Cao Wei state (d. 226) * G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
