|
Heinrich Barkhausen
Heinrich Georg Barkhausen (2 December 1881 – 20 February 1956), born in Bremen, was a German physicist. Growing up in a patrician Bremen family, he showed interest in natural sciences from an early age. He studied at the Technical University of Munich (1901), TU Berlin (1902) and University of Munich (1903) and Berlin before obtaining a doctorate at the University of Göttingen in 1907. He became professor of electrical engineering at the Technische Hochschule Dresden in 1911 at the age of 29, thus obtaining the world's first chair in this discipline. In 1919, he discovered the Barkhausen effect (named after him), which provided evidence for the magnetic domain theory of ferromagnetism. When the magnetic field through a piece of ferromagnetic material like iron is changing, the magnetization of the material changes in a series of tiny discontinuous jumps, which can be heard as a series of clicks in a loudspeaker attached to a coil of wire around the iron. It was lat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bremen (city)
Bremen ( Low German also: ''Breem'' or ''Bräm''), officially the City Municipality of Bremen (german: Stadtgemeinde Bremen, ), is the capital of the German state Free Hanseatic City of Bremen (''Freie Hansestadt Bremen''), a two-city-state consisting of the cities of Bremen and Bremerhaven. With about 570,000 inhabitants, the Hanseatic city is the 11th largest city of Germany and the second largest city in Northern Germany after Hamburg. Bremen is the largest city on the River Weser, the longest river flowing entirely in Germany, lying some upstream from its mouth into the North Sea, and is surrounded by the state of Lower Saxony. A commercial and industrial city, Bremen is, together with Oldenburg and Bremerhaven, part of the Bremen/Oldenburg Metropolitan Region, with 2.5 million people. Bremen is contiguous with the Lower Saxon towns of Delmenhorst, Stuhr, Achim, Weyhe, Schwanewede and Lilienthal. There is an exclave of Bremen in Bremerhaven, the "Citybremian Overseas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hysteresis
Hysteresis is the dependence of the state of a system on its history. For example, a magnet may have more than one possible magnetic moment in a given magnetic field, depending on how the field changed in the past. Plots of a single component of the moment often form a loop or hysteresis curve, where there are different values of one variable depending on the direction of change of another variable. This history dependence is the basis of memory in a hard disk drive and the remanence that retains a record of the Earth's magnetic field magnitude in the past. Hysteresis occurs in ferromagnetic and ferroelectric materials, as well as in the deformation of rubber bands and shape-memory alloys and many other natural phenomena. In natural systems it is often associated with irreversible thermodynamic change such as phase transitions and with internal friction; and dissipation is a common side effect. Hysteresis can be found in physics, chemistry, engineering, biology, and econ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Technical University Of Munich Alumni
Technical may refer to: * Technical (vehicle), an improvised fighting vehicle * Technical analysis, a discipline for forecasting the future direction of prices through the study of past market data * Technical drawing, showing how something is constructed or functions (also known as drafting) * Technical file, set of technical drawings * Technical death metal, a subgenre of death metal that focuses on complex rhythms, riffs, and song structures * Technical foul, an infraction of the rules in basketball usually concerning unsportsmanlike non-contact behavior * Technical rehearsal for a performance, often simply referred to as a technical * Technical support, a range of services providing assistance with technology products * Vocational education Vocational education is education that prepares people to work as a technician or to take up employment in a skilled craft or trade as a tradesperson or artisan. Vocational Education can also be seen as that type of educati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1956 Deaths
Events January * January 1 – The Anglo-Egyptian Condominium ends in Sudan. * January 8 – Operation Auca: Five U.S. evangelical Christian missionaries, Nate Saint, Roger Youderian, Ed McCully, Jim Elliot and Pete Fleming, are killed for trespassing by the Huaorani people of Ecuador, shortly after making contact with them. * January 16 – Egyptian leader Gamal Abdel Nasser vows to reconquer Palestine. * January 25– 26 – Finnish troops reoccupy Porkkala, after Soviet troops vacate its military base. Civilians can return February 4. * January 26 – The 1956 Winter Olympics open in Cortina d'Ampezzo, Italy. February * February 11 – British spies Guy Burgess and Donald Maclean resurface in the Soviet Union, after being missing for 5 years. * February 14– 25 – The 20th Congress of the Communist Party of the Soviet Union is held in Moscow. * February 16 – The 1956 World Figure Skating Championships open in Garmisch, West Germany. * February ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1881 Births
Events January–March * January 1– 24 – Siege of Geok Tepe: Russian troops under General Mikhail Skobelev defeat the Turkomans. * January 13 – War of the Pacific – Battle of San Juan and Chorrillos: The Chilean army defeats Peruvian forces. * January 15 – War of the Pacific – Battle of Miraflores: The Chileans take Lima, capital of Peru, after defeating its second line of defense in Miraflores. * January 24 – William Edward Forster, chief secretary for Ireland, introduces his Coercion Bill, which temporarily suspends habeas corpus so that those people suspected of committing an offence can be detained without trial; it goes through a long debate before it is accepted February 2. * January 25 – Thomas Edison and Alexander Graham Bell form the Oriental Telephone Company. * February 13 – The first issue of the feminist newspaper ''La Citoyenne'' is published by Hubertine Auclert. * February 16 – ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vow Of Allegiance Of The Professors Of The German Universities And High-Schools To Adolf Hitler And The National Socialistic State
Bekenntnis der Professoren an den Universitäten und Hochschulen zu Adolf Hitler und dem nationalsozialistischen Staat officially translated into English as the Vow of allegiance of the Professors of the German Universities and High-Schools to Adolf Hitler and the National Socialistic State was a document presented on 11 November 1933 at the Albert Hall in Leipzig. It had statements in German, English, Italian, and Spanish by selected German academics and included an appendix of signatories. The purge to remove academics and civil servants with Jewish ancestry began with a law being passed on 7 April 1933. This document was signed by those that remained in support of Nazi Germany. Martin Heidegger in his inaugural lecture in May 1933 as ''Rektor'', and who was later in October appointed "Führer of the university", said (translated): "The much celebrated "academic freedom" is being banished from the German university; for this freedom was not genuine, since it was only negative. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amplifier
An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It may increase the power significantly, or its main effect may be to boost the voltage or current ( power, voltage or current amplifier). It is a two-port electronic circuit that uses electric power from a power supply to increase the amplitude of a signal applied to its input terminals, producing a greater amplitude signal at its output. The ratio of output to input voltage, current, or power is termed gain (voltage, current, or power gain). An amplifier, by definition has gain greater than unity (if the gain is less than unity, the device is an attenuator). An amplifier can either be a separate piece of equipment or an electrical circuit contained within another device. Amplification is fundamental to modern electronics, and amplifiers are widely used in almost all electronic equipment. Amplifiers can be ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oscillation
Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum and alternating current. Oscillations can be used in physics to approximate complex interactions, such as those between atoms. Oscillations occur not only in mechanical systems but also in dynamic systems in virtually every area of science: for example the beating of the human heart (for circulation), business cycles in economics, predator–prey population cycles in ecology, geothermal geysers in geology, vibration of strings in guitar and other string instruments, periodic firing of nerve cells in the brain, and the periodic swelling of Cepheid variable stars in astronomy. The term '' vibration'' is precisely used to describe a mechanical oscillation. Oscillation, especially rapid oscillation, may be an undesirable phenomenon in p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Klystron
A klystron is a specialized linear-beam vacuum tube, invented in 1937 by American electrical engineers Russell and Sigurd Varian,Pond, Norman H. "The Tube Guys". Russ Cochran, 2008 p.31-40 which is used as an amplifier for high radio frequencies, from UHF up into the microwave range. Low-power klystrons are used as oscillators in terrestrial microwave relay communications links, while high-power klystrons are used as output tubes in UHF television transmitters, satellite communication, radar transmitters, and to generate the drive power for modern particle accelerators. In a klystron, an electron beam interacts with radio waves as it passes through resonant cavities, metal boxes along the length of a tube. The electron beam first passes through a cavity to which the input signal is applied. The energy of the electron beam amplifies the signal, and the amplified signal is taken from a cavity at the other end of the tube. The output signal can be coupled back into the input c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microwave
Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ranges as microwaves; the above broad definition includes both UHF and EHF (millimeter wave) bands. A more common definition in radio-frequency engineering is the range between 1 and 100 GHz (wavelengths between 0.3 m and 3 mm). In all cases, microwaves include the entire SHF band (3 to 30 GHz, or 10 to 1 cm) at minimum. Frequencies in the microwave range are often referred to by their IEEE radar band designations: S, C, X, Ku, K, or Ka band, or by similar NATO or EU designations. The prefix ' in ''microwave'' is not meant to suggest a wavelength in the micrometer range. Rather, it indicates that microwaves are "small" (having shorter wavelengths), compared to the radio waves used prior to microwave ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultrahigh Frequency
Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter (one decimeter). Radio waves with frequencies above the UHF band fall into the super-high frequency (SHF) or microwave frequency range. Lower frequency signals fall into the VHF (very high frequency) or lower bands. UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception. They are used for television broadcasting, cell phones, satellite communication including GPS, personal radio services including Wi-Fi and Bluetooth, walkie-talkies, cordless phones, satellite phones, and numerous other applications. The IEEE defines the UHF radar band as frequencies between 300 MHz and 1 GHz. Two other IEEE radar ban ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
