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Ronald Ernest Aitchison
Ronald Ernest Aitchison (29 December 1921 – 9 March 1996) was an Australian physicist and electronics engineer who contributed to a range of fields and technologies from solid-state devices to satellite imaging. He was born in Hurstville, New South Wales, Australia on 29 December 1921. Career From 1942 to 1945 Aitchison worked as an engineer with the Amalgamated Wireless Valve Company on the design and production of klystrons and radar magnetrons, which were new devices important to the war effort. He was also involved in work on semiconductor diodes, which were the forerunners of the revolution in electronics brought about by the advent of solid-state semiconductor components. In 1945 he joined the National Acoustic Laboratories where he worked on the design and construction of hearing aids for children. Aitchison was appointed as senior lecturer in Communications Engineering at the University of Sydney, which was the start of his 25-year teaching experience at that inst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hurstville, New South Wales
Hurstville is a suburb in Southern Sydney, New South Wales, Australia. It is 16 kilometres south of the Sydney CBD and is part of the St George area. Hurstville is the administrative centre of the local government area of the Georges River Council. The suburb is predominantly Asian Australian in character, with 63% of the population of Asian origin, among the highest in the country. Sometimes described as "Sydney's Real Chinatown", an estimated 37% of residents are immigrants from mainland China. History The name Hurstville is derived from the English 'hurst', meaning 'a wooded eminence', and 'ville', meaning 'town'. Aboriginal culture Although it is unknown when they first settled in the Hurstville area, the first inhabitants were Indigenous Australians. At the time of the arrival of the First Fleet, the Indigenous Australians residing in the area were of the Eora tribe, whose numbers spanned along the Georges River, from Botany Bay to present-day Liverpool. Europe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hurstville
Hurstville is a suburb in Southern Sydney, New South Wales, Australia. It is 16 kilometres south of the Sydney CBD and is part of the St George area. Hurstville is the administrative centre of the local government area of the Georges River Council. The suburb is predominantly Asian Australian in character, with 63% of the population of Asian origin, among the highest in the country. Sometimes described as "Sydney's Real Chinatown", an estimated 37% of residents are immigrants from mainland China. History The name Hurstville is derived from the English ' hurst', meaning 'a wooded eminence', and 'ville', meaning 'town'. Aboriginal culture Although it is unknown when they first settled in the Hurstville area, the first inhabitants were Indigenous Australians. At the time of the arrival of the First Fleet, the Indigenous Australians residing in the area were of the Eora tribe, whose numbers spanned along the Georges River, from Botany Bay to present-day Liverpool. European ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper Vapor Laser
Copper vapor laser (CVL) uses vapors of copper as the lasing medium in a 4-level laser. It produces green laser light at 510.6 nm and yellow laser light at 578.2 nm. The pulse width is typically from 5 to 60 ns, and peak power from 50 to 5000 kW. Its pulse repetition frequencies can be 2 to 100 kHz. The ''average power'' of CVLs can range from 25 W to more than 2 kW. It is one of the lasers that can be home built. W.T. Walter et al. were first who received laser generation of the copper vapour lasers (Walter W.T., Piltch M., Solimene N., Gould G. Pulsed laser action in atomic copper vapor. Bull. Amer. Phys. Soc., 1966, vol. 11, no. 1, p. 113.). In 1971 A.A.Isaev, M.A.Kazaryan and G.G.Petrash have invented a self-heating concept which allowed to tremendously increase efficiency of the cooper vapor laser and start their industrial production. (Isaev A.A., Kazaryan M.A., Petrash G.G. Effective Pulsed Copper-vapor Laser with High Average Generation Po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thyratron
A thyratron is a type of gas-filled tube used as a high-power electrical switch and controlled rectifier. Thyratrons can handle much greater currents than similar hard-vacuum tubes. Electron multiplication occurs when the gas becomes ionized, producing a phenomenon known as Townsend discharge. Gases used include mercury vapor, xenon, neon, and (in special high-voltage applications or applications requiring very short switching times) hydrogen. Unlike a vacuum tube (valve), a thyratron cannot be used to amplify signals linearly. In the 1920s, thyratrons were derived from early vacuum tubes such as the UV-200, which contained a small amount of argon gas to increase its sensitivity as a radio signal detector, and the German LRS relay tube, which also contained argon gas. Gas rectifiers, which predated vacuum tubes, such as the argon-filled General Electric " Tungar bulb" and the Cooper-Hewitt mercury-pool rectifier, also provided an influence. Irving Langmuir and G. S. Meikle of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macquarie Science Reform Movement
Macquarie science reform movement refers to the successful transformation of the degree system at Macquarie University in 1979 which followed an academic and political campaign initiated in 1977.F. J. Duarte, M. Golding, and B. Bulliman, Science degree, ''University News'' 1 (100) 16 (1977).Uni revolt simmers, ''Northern District Times'', 9 November 1977.2000 seek introduction of science degree at Macquarie, ''The Sydney Morning Herald'', 9 November 1977. Macquarie University, founded in 1964, adopted a degree structure modeled after the Oxbridge tradition where all graduating students were awarded a BA regardless of their field of study, with the exception of law students. Many science students saw this as a disadvantage and began to mobilize for reform of the degree structure. Thus, in 1977 a student organization, known as ''Students for a Science Degree'' (SSD), was formed with physicist Frank Duarte as chairman. SSD enlisted the support of science students, student politic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Clive Ward
John Clive Ward, (1 August 1924 – 6 May 2000) was a British-Australian physicist. He introduced the Ward–Takahashi identity, also known as "Ward Identity" (or "Ward's Identities"). Andrei Sakharov said Ward was one of the titans of quantum electrodynamics. He made significant contributions to quantum solid-state physics, statistical mechanics and the Ising model. Ward was one of the authors of the Standard Model of gauge particle interactions: his contributions were published in a series of papers he co-authored with Abdus Salam. He is also credited with being an early advocate of the use of Feynman diagrams. It has been said that physicists have made use of his principles and developments "often without knowing it, and generally without quoting him." In 1955, Ward was recruited to work at the Atomic Weapons Research Establishment at Aldermaston. There, he independently derived a version of the Teller-Ulam design, for which he has been called the "father of the Brit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solid-state Physics
Solid-state physics is the study of rigid matter, or solids, through methods such as quantum mechanics, crystallography, electromagnetism, and metallurgy. It is the largest branch of condensed matter physics. Solid-state physics studies how the large-scale properties of solid materials result from their atomic-scale properties. Thus, solid-state physics forms a theoretical basis of materials science. It also has direct applications, for example in the technology of transistors and semiconductors. Background Solid materials are formed from densely packed atoms, which interact intensely. These interactions produce the mechanical (e.g. hardness and Elasticity (physics), elasticity), Heat conduction, thermal, Electrical conduction, electrical, Magnetism, magnetic and Crystal optics, optical properties of solids. Depending on the material involved and the conditions in which it was formed, the atoms may be arranged in a regular, geometric pattern (crystal, crystalline solids, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Acoustic Laboratories
National may refer to: Common uses * Nation or country ** Nationality – a ''national'' is a person who is subject to a nation, regardless of whether the person has full rights as a citizen Places in the United States * National, Maryland, census-designated place * National, Nevada, ghost town * National, Utah, ghost town * National, West Virginia, unincorporated community Commerce * National (brand), a brand name of electronic goods from Panasonic * National Benzole (or simply known as National), former petrol station chain in the UK, merged with BP * National Car Rental, an American rental car company * National Energy Systems, a former name of Eco Marine Power * National Entertainment Commission, a former name of the Media Rating Council * National Motor Vehicle Company, Indianapolis, Indiana, USA 1900-1924 * National Supermarkets, a defunct American grocery store chain * National String Instrument Corporation, a guitar company formed to manufacture the first resonator gui ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diode
A diode is a two-terminal electronic component that conducts current primarily in one direction (asymmetric conductance); it has low (ideally zero) resistance in one direction, and high (ideally infinite) resistance in the other. A diode vacuum tube or thermionic diode is a vacuum tube with two electrodes, a heated cathode and a plate, in which electrons can flow in only one direction, from cathode to plate. A semiconductor diode, the most commonly used type today, is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals. Semiconductor diodes were the first semiconductor electronic devices. The discovery of asymmetric electrical conduction across the contact between a crystalline mineral and a metal was made by German physicist Ferdinand Braun in 1874. Today, most diodes are made of silicon, but other semiconducting materials such as gallium arsenide and germanium are also used. Among many uses, diodes are found in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semiconductor
A semiconductor is a material which has an electrical resistivity and conductivity, electrical conductivity value falling between that of a electrical conductor, conductor, such as copper, and an insulator (electricity), insulator, such as glass. Its electrical resistivity and conductivity, resistivity falls as its temperature rises; metals behave in the opposite way. Its conducting properties may be altered in useful ways by introducing impurities ("doping (semiconductor), doping") into the crystal structure. When two differently doped regions exist in the same crystal, a semiconductor junction is created. The behavior of charge carriers, which include electrons, ions, and electron holes, at these junctions is the basis of diodes, transistors, and most modern electronics. Some examples of semiconductors are silicon, germanium, gallium arsenide, and elements near the so-called "metalloid staircase" on the periodic table. After silicon, gallium arsenide is the second-most common s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetron
The cavity magnetron is a high-power vacuum tube used in early radar systems and currently in microwave ovens and linear particle accelerators. It generates microwaves using the interaction of a stream of electrons with a magnetic field while moving past a series of cavity resonators, which are small, open cavities in a metal block. Electrons pass by the cavities and cause microwaves to oscillate within, similar to the functioning of a whistle producing a tone when excited by an air stream blown past its opening. The resonant frequency of the arrangement is determined by the cavities' physical dimensions. Unlike other vacuum tubes, such as a klystron or a traveling-wave tube (TWT), the magnetron cannot function as an amplifier for increasing the intensity of an applied microwave signal; the magnetron serves solely as an oscillator, generating a microwave signal from direct current electricity supplied to the vacuum tube. The use of magnetic fields as a means to control the flo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radar
Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna (often the same antenna is used for transmitting and receiving) and a receiver and processor to determine properties of the objects. Radio waves (pulsed or continuous) from the transmitter reflect off the objects and return to the receiver, giving information about the objects' locations and speeds. Radar was developed secretly for military use by several countries in the period before and during World War II. A key development was the cavity magnetron in the United Kingdom, which allowed the creation of relatively small systems with sub-meter resolution. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
