Laboratory For Applied Physics

1) Американизм: Low Frequency Assignment Problem

2) Шутливое выражение: Live Free And Pee

3) Сокращение: Local Fire Alarm Panel

4) Университет: Laboratory For Applied Physics

5) Транспорт: Left Foot Accelerator Pedal

6) Сетевые технологии: Lightweight Flow Accounting Protocol

7) Расширение файла: Lightweight Flow Admission Protocol

SUBJECT AREA: Chemical technology, Electricity

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Maxwell attended school at the Edinburgh Academy and at the age of 16 went on to study at Edinburgh University. In 1850 he entered Trinity College, Cambridge, where he graduated four years later as Second Wrangler with the award of the Smith's Prize. Two years later he was appointed Professor at Marischal College, Aberdeen, where he married the Principal's daughter. In 1860 he moved to King's College London, but on the death of his father five years later, Maxwell returned to the family home in Scotland, where he continued his researches as far as the life of a gentleman farmer allowed. This rural existence was interrupted in 1874 when he was persuaded to accept the chair of Cavendish Professor of Experimental Physics at Cambridge. Unfortunately, in 1879 he contracted the cancer that brought his brilliant career to an untimely end. While at Cambridge, Maxwell founded the Cavendish Laboratory for research in physics. A succession of distinguished physicists headed the laboratory, making it one of the world's great centres for notable discoveries in physics.

During the mid-1850s, Maxwell worked towards a theory to explain electrical and magnetic phenomena in mathematical terms, culminating in 1864 with the formulation of the fundamental equations of electromagnetism (Maxwell's equations). These equations also described the propagation of light, for he had shown that light consists of transverse electromagnetic waves in a hypothetical medium, the "ether". This great synthesis of theories uniting a wide range of phenomena is worthy to set beside those of Sir Isaac Newton and Einstein. Like all such syntheses, it led on to further discoveries. Maxwell himself had suggested that light represented only a small part of the spectrum of electromagnetic waves, and in 1888 Hertz confirmed the discovery of another small part of the spectrum, radio waves, with momentous implications for the development of telecommunication technology. Maxwell contributed to the kinetic theory of gases, which by then were viewed as consisting of a mass of randomly moving molecules colliding with each other and with the walls of the containing vessel. From 1869 Maxwell applied statistical methods to describe the molecular motion in mathematical terms. This led to a greater understanding of the behaviour of gases, with important consequences for the chemical industry.

Of more direct technological application was Maxwell's work on colour vision, begun in 1849, showing that all colours could be derived from the three primary colours, red, yellow and blue. This enabled him in 1861 to produce the first colour photograph, of a tartan. Maxwell's discoveries about colour vision were quickly taken up and led to the development of colour printing and photography.

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SUBJECT AREA: Electronics and information technology, Telecommunications

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After attending schools in Palo Alto and Halcyon, Russell Varian went to Stanford University, gaining his BA in 1925 and his MA in 1927 despite illness and being dyslexic. His family being in need of financial help, he first worked for six months for Bush Electric in San Francisco and then for an oil company in Texas, returning to San Francisco in 1930 to join Farnsworth's Television Laboratory. After a move to Philadelphia, in 1933 the laboratory closed and Russell tried to take up a PhD course at Stanford but was rejected, so he trained as a teacher. However, although he did some teaching at Stanford it was not to be his career, for in 1935 he joined his brothers Sigurd and Eric in the setting up of a home laboratory.

There, with William Hansen, a former colleague of Russell's at Stanford, they worked on the development of microwave oscillators, based on some of the latter's ideas. By 1937 they had made sufficient progress on an electron velocity-bunching tube, which they called the klystron, to obtain an agreement with the university to provide laboratory facilities in return for a share of any proceeds. By August that year they were able to produce continuous power at a wavelength of 13 cm. Clearly needing greater resources to develop and manufacture the tube, and with a possible war looming, a deal was struck with the Sperry Gyroscope Company to finance the work, which was transferred to the East Coast.

In 1946, after the death of his first wife, Russell returned to Palo Alto, and in 1948 the brothers and Hansen founded Varian Associates to make microwave tubes for transmitters and linear accelerators and nuclear magnetic-resonance detectors. Subsequent research also resulted in the development of a satellite-borne magnetometer for measuring the earth's magnetic field.

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See also: Varian, Sigurd Fergus

SUBJECT AREA: Electronics and information technology

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Born on a cattle ranch, Forrester obtained a BSc in electrical engineering at the University of Nebraska in 1939 and his MSc at the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts, where he remained to teach and carry out research. Becoming interested in computing, he established the Digital Computer Laboratory at MIT in 1945 and became involved in the construction of Whirlwind I, an early general-purpose computer completed in March 1951 and used for flight-simulation by the US Army Air Force. Finding the linear memories then available for storing data a major limiting factor in the speed at which computers were able to operate, he developed a three-dimensional store based on the binary switching of the state of small magnetic cores that could be addressed and switched by a matrix of wires carrying pulses of current. The machine used parallel synchronous fixed-point computing, with fifteen binary digits and a plus sign, i.e. 16 bits in all, and contained 5,000 vacuum tubes, eleven semiconductors and a 2 MHz clock for the arithmetic logic unit. It occupied a two-storey building and consumed 150kW of electricity. From his experience with the development and use of computers, he came to realize their great potential for the simulation and modelling of real situations and hence for the solution of a variety of management problems, using data communications and the technique now known as interactive graphics. His later career was therefore in this field, first at the MIT Lincoln Laboratory in Lexington, Massachusetts (1951) and subsequently (from 1956) as Professor at the Sloan School of Management at the Massachusetts Institute of Technology.

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See also: Burks, Arthur Walter; Goldstine, Herman H.; Wilkes, Maurice Vincent; Williams, Sir Frederic Calland

SUBJECT AREA: Electricity, Metallurgy

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Coolidge obtained his BS from the Massachusetts Institute of Technology (MIT) in 1896, and his PhD (physics) from the University of Leipzig in 1899. He was appointed Assistant Professor of Physics at MIT in 1904, and in 1905 he joined the staff of the General Electric Company's research laboratory at Schenectady. In 1905 Schenectady was trying to make tungsten-filament lamps to counter the competition of the tantalum-filament lamps then being produced by their German rival Siemens. The first tungsten lamps made by Just and Hanaman in Vienna in 1904 had been too fragile for general use. Coolidge and his life-long collaborator, Colin G. Fink, succeeded in 1910 by hot-working directly dense sintered tungsten compacts into wire. This success was the result of a flash of insight by Coolidge, who first perceived that fully recrystallized tungsten wire was always brittle and that only partially work-hardened wire retained a measure of ductility. This grasped, a process was developed which induced ductility into the wire by hot-working at temperatures below those required for full recrystallization, so that an elongated fibrous grain structure was progressively developed. Sintered tungsten ingots were swaged to bar at temperatures around 1,500°C and at the end of the process ductile tungsten filament wire was drawn through diamond dies around 550°C. This process allowed General Electric to dominate the world lamp market. Tungsten lamps consumed only one-third the energy of carbon lamps, and for the first time the cost of electric lighting was reduced to that of gas. Between 1911 and 1914, manufacturing licences for the General Electric patents had been granted for most of the developed work. The validity of the General Electric monopoly was bitterly contested, though in all the litigation that followed, Coolidge's fibering principle was upheld. Commercial arrangements between General Electric and European producers such as Siemens led to the name "Osram" being commonly applied to any lamp with a drawn tungsten filament. In 1910 Coolidge patented the use of thoria as a particular additive that greatly improved the high-temperature strength of tungsten filaments. From this development sprang the technique of "dispersion strengthening", still being widely used in the development of high-temperature alloys in the 1990s. In 1913 Coolidge introduced the first controllable hot-cathode X-ray tube, which had a tungsten target and operated in vacuo rather than in a gaseous atmosphere. With this equipment, medical radiography could for the first time be safely practised on a routine basis. During the First World War, Coolidge developed portable X-ray units for use in field hospitals, and between the First and Second World Wars he introduced between 1 and 2 million X-ray machines for cancer treatment and for industrial radiography. He became Director of the Schenectady laboratory in 1932, and from 1940 until 1944 he was Vice-President and Director of Research. After retirement he was retained as an X-ray consultant, and in this capacity he attended the Bikini atom bomb trials in 1946. Throughout the Second World War he was a member of the National Defence Research Committee.

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SUBJECT AREA: Broadcasting, Electronics and information technology, Photography, film and optics, Recording, Telecommunications

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De Forest was born into the family of a Congregational minister that moved to Alabama in 1879 when the father became President of a college for African-Americans; this was a position that led to the family's social ostracism by the white community. By the time he was 13 years old, De Forest was already a keen mechanical inventor, and in 1893, rejecting his father's plan for him to become a clergyman, he entered the Sheffield Scientific School of Yale University. Following his first degree, he went on to study the propagation of electromagnetic waves, gaining a PhD in physics in 1899 for his thesis on the "Reflection of Hertzian Waves from the Ends of Parallel Wires", probably the first US thesis in the field of radio.

He then joined the Western Electric Company in Chicago where he helped develop the infant technology of wireless, working his way up from a modest post in the production area to a position in the experimental laboratory. There, working alone after normal working hours, he developed a detector of electromagnetic waves based on an electrolytic device similar to that already invented by Fleming in England. Recognizing his talents, a number of financial backers enabled him to set up his own business in 1902 under the name of De Forest Wireless Telegraphy Company; he was soon demonstrating wireless telegraphy to interested parties and entering into competition with the American Marconi Company.

Despite the failure of this company because of fraud by his partners, he continued his experiments; in 1907, by adding a third electrode, a wire mesh, between the anode and cathode of the thermionic diode invented by Fleming in 1904, he was able to produce the amplifying device now known as the triode valve and achieve a sensitivity of radio-signal reception much greater than possible with the passive carborundum and electrolytic detectors hitherto available. Patented under the name Audion, this new vacuum device was soon successfully used for experimental broadcasts of music and speech in New York and Paris. The invention of the Audion has been described as the beginning of the electronic era. Although much development work was required before its full potential was realized, the Audion opened the way to progress in all areas of sound transmission, recording and reproduction. The patent was challenged by Fleming and it was not until 1943 that De Forest's claim was finally recognized.

Overcoming the near failure of his new company, the De Forest Radio Telephone Company, as well as unsuccessful charges of fraudulent promotion of the Audion, he continued to exploit the potential of his invention. By 1912 he had used transformer-coupling of several Audion stages to achieve high gain at radio frequencies, making long-distance communication a practical proposition, and had applied positive feedback from the Audion output anode to its input grid to realize a stable transmitter oscillator and modulator. These successes led to prolonged patent litigation with Edwin Armstrong and others, and he eventually sold the manufacturing rights, in retrospect often for a pittance.

During the early 1920s De Forest began a fruitful association with T.W.Case, who for around ten years had been working to perfect a moving-picture sound system. De Forest claimed to have had an interest in sound films as early as 1900, and Case now began to supply him with photoelectric cells and primitive sound cameras. He eventually devised a variable-density sound-on-film system utilizing a glow-discharge modulator, the Photion. By 1926 De Forest's Phonofilm had been successfully demonstrated in over fifty theatres and this system became the basis of Movietone. Though his ideas were on the right lines, the technology was insufficiently developed and it was left to others to produce a system acceptable to the film industry. However, De Forest had played a key role in transforming the nature of the film industry; within a space of five years the production of silent films had all but ceased.

In the following decade De Forest applied the Audion to the development of medical diathermy. Finally, after spending most of his working life as an independent inventor and entrepreneur, he worked for a time during the Second World War at the Bell Telephone Laboratories on military applications of electronics.

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