(not+developed)

SUBJECT AREA: Textiles

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Radcliffe was brought up in the textile industry and learned carding and spinning as a child. When he was old enough, he became a weaver. It was a time when there were not enough weavers to work up all the yarn being spun on the recently invented spinning machines, so some yarn was exported. Radcliffe regarded this as a sin; meetings were held to prohibit the export, and Radcliffe promised to use his best endeavours to discover means to work up the yarn in England. He owned a mill at Mellor and by 1801 was employing over 1,000 hand-loom weavers. He wanted to improve their efficiency so they could compete against power looms, which were beginning to be introduced at that time.

His first step was to divide up as much as possible the different weaving processes, not unlike the plan adopted by Arkwright in spinning. In order to strengthen the warp yarns made of cotton and to reduce their tendency to fray during weaving, it was customary to apply an adhesive substance such as starch paste. This was brushed on as the warp was unwound from the back beam during weaving, so only short lengths could be treated before being dried. Instead of dressing the warp in the loom as was hitherto done, Radcliffe had it dressed in a separate machine, relieving the weaver of the trouble and saving the time wasted by the method previously used. Radcliffe employed a young man names Thomas Johnson, who proved to be a clever mechanic. Radcliffe patented his inventions in Johnson's name to avoid other people, especially foreigners, finding out his ideas. He took out his first patent, for a dressing machine, in March 1803 and a second the following year. The combined result of the two patents was the introduction of a beaming machine and a dressing machine which, in addition to applying the paste to the yarns and then drying them, wound them onto a beam ready for the loom. These machines enabled the weaver to work a loom with fewer stoppages; however, Radcliffe did not anticipate that his method of sizing would soon be applied to power looms as well and lead to the commercial success of powered weaving. Other manufacturers quickly adopted Radcliffe's system, and Radcliffe himself soon had to introduce power looms in his own business.

Radcliffe improved the hand looms themselves when, with the help of Johnson, he devised a cloth taking-up motion that wound the woven cloth onto a roller automatically as the weaver operated the loom. Radcliffe and Johnson also developed the "dandy loom", which was a more compact form of hand loom and was also later adapted for weaving by power. Radcliffe was among the witnesses before the Parliamentary Committee which in 1808 awarded Edmund Cartwright a grant for his invention of the power loom. Later Radcliffe was unsuccessfully to petition Parliament for a similar reward for his contributions to the introduction of power weaving. His business affairs ultimately failed partly through his own obstinacy and his continued opposition to the export of cotton yarn. He lived to be 81 years old and was buried in Mellor churchyard.

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SUBJECT AREA: Recording

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He was the descendant of a Scottish family who emigrated to France in 1688. He trained as a printer and later became a proof corrector in printing houses catering predominantly for scientific publishers. He became interested in shorthand systems and eventually turned his interest to making a permanent record of sounds in air. At the time it was already known (Young, Duhamel, Wertheim) to record vibrations of bodies. He made a theoretical study and deposited under sealed wrapper a note in the Académie des Sciences on 26 January 1857. He approached the scientific instrument maker Froment and was able to pay for the manufacture of one instrument due to support from the Société d'Encouragement à l'Industrie Nationale. This funding body obtained a positive report from the physicist Lissajous on 6 January 1858. A new model phonautograph was constructed in collaboration with the leading scientific instrument maker in Paris at the time, Rudolph Koenig, and a contract was signed in 1859. The instrument was a success, and Koenig published a collection of traces in 1864.

Although the membrane was parallel to the rotating surface, a primitive lever system generated lateral movements of a bristle which scratched curves in a thin layer of lampblack on the rotating surface. The curves were not necessarily representative of the vibrations in the air. Scott did not imagine the need for reproducing a recorded sound; rather, his intention was to obtain a trace that would lend itself to mathematical analysis and visual recognition of sounds. Obviously the latter did not require the same degree of linearity as the former. When Scott learned that similar apparatus had been built independently in the USA, he requested that his sealed wrapper be opened on 15 July 1861 in order to prove his scientific priority. The contract with Koenig left Scott without influence over his instrument, and eventually he became convinced that everyone else, including Edison in the end, had stolen his invention. Towards the end of his life he became interested mainly in the history of printing, and he was involved in the publishing of a series of books about books.

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выбор оптимальных параметров
—
[А.С.Гольдберг. Англо-русский энергетический словарь. 2006 г.]

Тематики

• энергетика в целом

EN

• optimization

 

определение оптимальных характеристик
—
[ http://slovarionline.ru/anglo_russkiy_slovar_neftegazovoy_promyishlennosti/]

Тематики

• нефтегазовая промышленность

EN

• optimization

 

оптимизация
Процесс отыскания варианта, соответствующего критерию оптимальности
[Терминологический словарь по строительству на 12 языках (ВНИИИС Госстроя СССР)]

оптимизация
1. Процесс нахождения экстремума функции, т.е. выбор наилучшего варианта из множества возможных, процесс выработки оптимальных решений; 2. Процесс приведения системы в наилучшее (оптимальное) состояние. Иначе говоря, первое определение трактует термин «О.» как факт выработки и принятия оптимального решения (в широком смысле этих слов); мы выясняем, какое состояние изучаемой системы будет наилучшим с точки зрения предъявляемых к ней требований (критерия оптимальности) и рассматриваем такое состояние как цель. В этом смысле применяется также термин «субоптимизация» в случаях, когда отыскивается оптимум по какому-либо одному критерию из нескольких в векторной задаче оптимизации (см. Оптимальность по Парето, Векторная оптимизация). Второе определение имеет в виду процесс выполнения этого решения: т.е. перевод системы от существующего к искомому оптимальному состоянию. В зависимости от вида используемых критериев оптимальности (целевых функций или функционалов) и ограничений модели (множества допустимых решений) различают скалярную О., векторную О., мно¬гокритериальную О., стохастическую О (см. Стохастическое программирование), гладкую и негладкую (см. Гладкая функция), дискретную и непрерывную (см. Дискретность, Непрерывность), выпуклую и вогнутую (см. Выпуклость, вогнутость) и др. Численные методы О., т.е. методы построения алгоритмов нахождения оп¬тимальных значений целевых функций и соответствующих точек области допустимых значений — развитой отдел современной вычислительной математики. См. Оптимальная задача.
[ http://slovar-lopatnikov.ru/]

Параллельные тексты EN-RU из ABB Review. Перевод компании Интент

 

дистанционное техническое обслуживание
Техническое обслуживание объекта, проводимое под управлением персонала без его непосредственного присутствия.
[ОСТ 45.152-99 ]

Параллельные тексты EN-RU из ABB Review. Перевод компании Интент

 

дистанционное техническое обслуживание
Техническое обслуживание объекта, проводимое под управлением персонала без его непосредственного присутствия.
[ОСТ 45.152-99 ]

Параллельные тексты EN-RU из ABB Review. Перевод компании Интент

adjective (having made a lot of progress; at a high level: an advanced computer course; in the advanced stages of the illness.) avanzado

tr[əd'vɑːnst]

adjective

1 avanzado,-a

\

of advanced years de avanzada edad

advanced [æd'væntst, əd-] adj

1) developed: avanzado, desarrollado

2) precocious: adelantado, precoz

3) higher: superior

• adelantado, -a adj.

• anticipado, -a adj.

• avanzado, -a adj.

• precoz adj.

adjective <civilization/technology/course> avanzado; < student> avanzado, adelantado

1. ADJ

1) (=developed) [civilization, society] avanzado

2) (=not elementary) [course, level, studies] avanzado, superior; [student] (de nivel) avanzado

3) (=precocious) adelantado

4) (=modern) [ideas] avanzado

5) (in time) [stage] avanzado; [disease] de grado avanzado

* * *

adjective <civilization/technology/course> avanzado; < student> avanzado, adelantado

SUBJECT AREA: Chemical technology, Weapons and armour

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His family came from Germany and he was the son of a music master. He first became interested in science at the age of 14, when visiting his mineralogist uncle in Hamburg, and studied chemistry at the Royal Polytechnic Institution in London. In 1845 he became one of the twenty-six founding students, under A.W.von Hofmann, of the Royal College of Chemistry. Such was his aptitude for the subject that within two years he became von Hermann's assistant and demonstrator. In 1851 Abel was appointed Lecturer in Chemistry, succeeding Michael Faraday, at the Royal Military Academy, Woolwich, and it was while there that he wrote his Handbook of Chemistry, which was co-authored by his assistant, Charles Bloxam.

Abel's four years at the Royal Military Academy served to foster his interest in explosives, but it was during his thirty-four years, beginning in 1854, as Ordnance Chemist at the Royal Arsenal and at Woolwich that he consolidated and developed his reputation as one of the international leaders in his field. In 1860 he was elected a Fellow of the Royal Society, but it was his studies during the 1870s into the chemical changes that occur during explosions, and which were the subject of numerous papers, that formed the backbone of his work. It was he who established the means of storing gun-cotton without the danger of spontaneous explosion, but he also developed devices (the Abel Open Test and Close Test) for measuring the flashpoint of petroleum. He also became interested in metal alloys, carrying out much useful work on their composition. A further avenue of research occurred in 1881 when he was appointed a member of the Royal Commission set up to investigate safety in mines after the explosion that year in the Sealham Colliery. His resultant study on dangerous dusts did much to further understanding on the use of explosives underground and to improve the safety record of the coal-mining industry. The achievement for which he is most remembered, however, came in 1889, when, in conjunction with Sir James Dewar, he invented cordite. This stable explosive, made of wood fibre, nitric acid and glycerine, had the vital advantage of being a "smokeless powder", which meant that, unlike the traditional ammunition propellant, gunpowder ("black powder"), the firer's position was not given away when the weapon was discharged. Although much of the preliminary work had been done by the Frenchman Paul Vieille, it was Abel who perfected it, with the result that cordite quickly became the British Army's standard explosive.

Abel married, and was widowed, twice. He had no children, but died heaped in both scientific honours and those from a grateful country.

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SUBJECT AREA: Aerospace

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The Breguet family had been manufacturing fine clocks since before the French Revolution, but Louis Breguet and his brother Jacques used their mechanical skills to produce a helicopter, or "gyroplane" as they named it. It was a complex machine with four biplane rotors (i.e. thirty-two lifting surfaces). Louis Breguet had carried out many tests to determine the most suitable rotor design. The Breguet brothers were assisted by Professor Charles Richet and the Breguet-Richet No. 1 was tested in September 1907 when it succeeded in lifting itself, and its pilot, to a height of 1.5 metres. Unfortunately, the gyroplane was rather unstable and four helpers had to steady it; consequently, the flight did not qualify as a "free" flight. This was achieved two months later, also in France, by Paul Cornu who made a 20-second free flight.

Louis Breguet turned his attention to aeroplane design and produced a tractor biplane when most other biplanes followed the Wright brothers' layout with a forward elevator and pusher propeller. The Breguet I made quite an impression at the 1909 Reims meeting, but the Breguet IV created a world record the following year by carrying six people. During the First World War the Breguet Type 14 bomber was widely used by French and American squadrons. Between the First and Second World Wars a wide variety of designs were produced, including flying boats and another helicopter, the Breguet- Dorand Gyroplane which flew for over one hour in 1936. The Breguet company survived World War II and in the late 1940s developed a successful four-engined airliner/transport, the Deux-Ponts, which had a bulbous double-deck fuselage.

Breguet was an innovative designer, although his designs were functional rather than elegant. He was an early advocate of metal construction and developed an oleo- (oil-spring) undercarriage leg.

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SUBJECT AREA: Civil engineering, Land transport, Mechanical, pneumatic and hydraulic engineering, Ports and shipping, Public utilities, Railways and locomotives

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The son of Marc Isambard Brunel and Sophia Kingdom, he was educated at a private boarding-school in Hove. At the age of 14 he went to the College of Caen and then to the Lycée Henri-Quatre in Paris, after which he was apprenticed to Louis Breguet. In 1822 he returned from France and started working in his father's office, while spending much of his time at the works of Maudslay, Sons \& Field.

From 1825 to 1828 he worked under his father on the construction of the latter's Thames Tunnel, occupying the position of Engineer-in-Charge, exhibiting great courage and presence of mind in the emergencies which occurred not infrequently. These culminated in January 1828 in the flooding of the tunnel and work was suspended for seven years. For the next five years the young engineer made abortive attempts to find a suitable outlet for his talents, but to little avail. Eventually, in 1831, his design for a suspension bridge over the River Avon at Clifton Gorge was accepted and he was appointed Engineer. (The bridge was eventually finished five years after Brunel's death, as a memorial to him, the delay being due to inadequate financing.) He next planned and supervised improvements to the Bristol docks. In March 1833 he was appointed Engineer of the Bristol Railway, later called the Great Western Railway. He immediately started to survey the route between London and Bristol that was completed by late August that year. On 5 July 1836 he married Mary Horsley and settled into 18 Duke Street, Westminster, London, where he also had his office. Work on the Bristol Railway started in 1836. The foundation stone of the Clifton Suspension Bridge was laid the same year. Whereas George Stephenson had based his standard railway gauge as 4 ft 8½ in (1.44 m), that or a similar gauge being usual for colliery wagonways in the Newcastle area, Brunel adopted the broader gauge of 7 ft (2.13 m). The first stretch of the line, from Paddington to Maidenhead, was opened to traffic on 4 June 1838, and the whole line from London to Bristol was opened in June 1841. The continuation of the line through to Exeter was completed and opened on 1 May 1844. The normal time for the 194-mile (312 km) run from Paddington to Exeter was 5 hours, at an average speed of 38.8 mph (62.4 km/h) including stops. The Great Western line included the Box Tunnel, the longest tunnel to that date at nearly two miles (3.2 km).

Brunel was the engineer of most of the railways in the West Country, in South Wales and much of Southern Ireland. As railway networks developed, the frequent break of gauge became more of a problem and on 9 July 1845 a Royal Commission was appointed to look into it. In spite of comparative tests, run between Paddington-Didcot and Darlington-York, which showed in favour of Brunel's arrangement, the enquiry ruled in favour of the narrow gauge, 274 miles (441 km) of the former having been built against 1,901 miles (3,059 km) of the latter to that date. The Gauge Act of 1846 forbade the building of any further railways in Britain to any gauge other than 4 ft 8 1/2 in (1.44 m).

The existence of long and severe gradients on the South Devon Railway led to Brunel's adoption of the atmospheric railway developed by Samuel Clegg and later by the Samuda brothers. In this a pipe of 9 in. (23 cm) or more in diameter was laid between the rails, along the top of which ran a continuous hinged flap of leather backed with iron. At intervals of about 3 miles (4.8 km) were pumping stations to exhaust the pipe. Much trouble was experienced with the flap valve and its lubrication—freezing of the leather in winter, the lubricant being sucked into the pipe or eaten by rats at other times—and the experiment was abandoned at considerable cost.

Brunel is to be remembered for his two great West Country tubular bridges, the Chepstow and the Tamar Bridge at Saltash, with the latter opened in May 1859, having two main spans of 465 ft (142 m) and a central pier extending 80 ft (24 m) below high water mark and allowing 100 ft (30 m) of headroom above the same. His timber viaducts throughout Devon and Cornwall became a feature of the landscape. The line was extended ultimately to Penzance.

As early as 1835 Brunel had the idea of extending the line westwards across the Atlantic from Bristol to New York by means of a steamship. In 1836 building commenced and the hull left Bristol in July 1837 for fitting out at Wapping. On 31 March 1838 the ship left again for Bristol but the boiler lagging caught fire and Brunel was injured in the subsequent confusion. On 8 April the ship set sail for New York (under steam), its rival, the 703-ton Sirius, having left four days earlier. The 1,340-ton Great Western arrived only a few hours after the Sirius. The hull was of wood, and was copper-sheathed. In 1838 Brunel planned a larger ship, some 3,000 tons, the Great Britain, which was to have an iron hull.

The Great Britain was screwdriven and was launched on 19 July 1843,289 ft (88 m) long by 51 ft (15.5 m) at its widest. The ship's first voyage, from Liverpool to New York, began on 26 August 1845. In 1846 it ran aground in Dundrum Bay, County Down, and was later sold for use on the Australian run, on which it sailed no fewer than thirty-two times in twenty-three years, also serving as a troop-ship in the Crimean War. During this war, Brunel designed a 1,000-bed hospital which was shipped out to Renkioi ready for assembly and complete with shower-baths and vapour-baths with printed instructions on how to use them, beds and bedding and water closets with a supply of toilet paper! Brunel's last, largest and most extravagantly conceived ship was the Great Leviathan, eventually named The Great Eastern, which had a double-skinned iron hull, together with both paddles and screw propeller. Brunel designed the ship to carry sufficient coal for the round trip to Australia without refuelling, thus saving the need for and the cost of bunkering, as there were then few bunkering ports throughout the world. The ship's construction was started by John Scott Russell in his yard at Millwall on the Thames, but the building was completed by Brunel due to Russell's bankruptcy in 1856. The hull of the huge vessel was laid down so as to be launched sideways into the river and then to be floated on the tide. Brunel's plan for hydraulic launching gear had been turned down by the directors on the grounds of cost, an economy that proved false in the event. The sideways launch with over 4,000 tons of hydraulic power together with steam winches and floating tugs on the river took over two months, from 3 November 1857 until 13 January 1858. The ship was 680 ft (207 m) long, 83 ft (25 m) beam and 58 ft (18 m) deep; the screw was 24 ft (7.3 m) in diameter and paddles 60 ft (18.3 m) in diameter. Its displacement was 32,000 tons (32,500 tonnes).

The strain of overwork and the huge responsibilities that lay on Brunel began to tell. He was diagnosed as suffering from Bright's disease, or nephritis, and spent the winter travelling in the Mediterranean and Egypt, returning to England in May 1859. On 5 September he suffered a stroke which left him partially paralysed, and he died ten days later at his Duke Street home.

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SUBJECT AREA: Medical technology

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He entered the university of Lyon as a medical student in 1890, but although attached to the Chasseurs Alpins as a surgeon, and to the department of anatomy, he did not qualify as a doctor until 1900. Soon after, he developed an interest in the repair of blood vessels and reported his first successes in 1902.

In consequence of local political difficulties he left for Paris, and after a further year, in 1904, he became Assistant in Physiology at the University of Chicago. His further development of vascular surgical advances led to organ transplants in animals. By 1908 he had moved to in vitro cultivation of heart tissue from a chick embryo (a culture of which, in the care of an assistant, outlived him).

He returned to service in the French Army in 1914 and was associated with Dakin in developing the irrigation treatment of infected wounds. In 1930 he initiated a programme aimed at the cultivation of whole organs, and with the assistance of a pump developed by Charles Lindbergh he succeeded in maintaining thyroid gland and kidney tissue for some weeks. Something of a mystic, Carrel returned to France in 1939 to head his Institute for the Study of Human Problems.

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SUBJECT AREA: Metallurgy

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Soon after graduating from the Ecole des Mines at St-Etienne in 1910, Chevenard joined the Société de Commentry Fourchambault et Decazeville at their steelworks at Imphy, where he remained for the whole of his career. Imphy had for some years specialized in the production of nickel steels. From this venture emerged the first austenitic nickel-chromium steel, containing 6 per cent chromium and 22–4 per cent nickel and produced commercially in 1895. Most of the alloys required by Guillaume in his search for the low-expansion alloy Invar were made at Imphy. At the Imphy Research Laboratory, established in 1911, Chevenard conducted research into the development of specialized nickel-based alloys. His first success followed from an observation that some of the ferro-nickels were free from the low-temperature brittleness exhibited by conventional steels. To satisfy the technical requirements of Georges Claude, the French cryogenic pioneer, Chevenard was then able in 1912 to develop an alloy containing 55–60 per cent nickel, 1–3 per cent manganese and 0.2–0.4 per cent carbon. This was ductile down to −190°C, at which temperature carbon steel was very brittle.

By 1916 Elinvar, a nickel-iron-chromium alloy with an elastic modulus that did not vary appreciably with changes in ambient temperature, had been identified. This found extensive use in horology and instrument manufacture, and even for the production of high-quality tuning forks. Another very popular alloy was Platinite, which had the same coefficient of thermal expansion as platinum and soda glass. It was used in considerable quantities by incandescent-lamp manufacturers for lead-in wires. Other materials developed by Chevenard at this stage to satisfy the requirements of the electrical industry included resistance alloys, base-metal thermocouple combinations, magnetically soft high-permeability alloys, and nickel-aluminium permanent magnet steels of very high coercivity which greatly improved the power and reliability of car magnetos. Thermostatic bimetals of all varieties soon became an important branch of manufacture at Imphy.

During the remainder of his career at Imphy, Chevenard brilliantly elaborated the work on nickel-chromium-tungsten alloys to make stronger pressure vessels for the Haber and other chemical processes. Another famous alloy that he developed, ATV, contained 35 per cent nickel and 11 per cent chromium and was free from the problem of stress-induced cracking in steam that had hitherto inhibited the development of high-power steam turbines. Between 1912 and 1917, Chevenard recognized the harmful effects of traces of carbon on this type of alloy, and in the immediate postwar years he found efficient methods of scavenging the residual carbon by controlled additions of reactive metals. This led to the development of a range of stabilized austenitic stainless steels which were free from the problems of intercrystalline corrosion and weld decay that then caused so much difficulty to the manufacturers of chemical plant.

Chevenard soon concluded that only the nickel-chromium system could provide a satisfactory basis for the subsequent development of high-temperature alloys. The first published reference to the strengthening of such materials by additions of aluminium and/or titanium occurs in his UK patent of 1929. This strengthening approach was adopted in the later wartime development in Britain of the Nimonic series of alloys, all of which depended for their high-temperature strength upon the precipitated compound Ni3Al.

In 1936 he was studying the effect of what is now known as "thermal fatigue", which contributes to the eventual failure of both gas and steam turbines. He then published details of equipment for assessing the susceptibility of nickel-chromium alloys to this type of breakdown by a process of repeated quenching. Around this time he began to make systematic use of the thermo-gravimetrie balance for high-temperature oxidation studies.

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SUBJECT AREA: Land transport, Railways and locomotives

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Churchward was articled to the Locomotive Superintendent of the South Devon Railway in 1873, and when the South Devon was absorbed by the Great Western Railway in 1876 he moved to the latter's Swindon works. There he rose by successive promotions to become Works Manager in 1896, and in 1897 Chief Assistant to William Dean, who was Locomotive Carriage and Wagon Superintendent, in which capacity Churchward was allowed extensive freedom of action. Churchward eventually succeeded Dean in 1902: his title changed to Chief Mechanical Engineer in 1916.

In locomotive design, Churchward adopted the flat-topped firebox invented by A.J.Belpaire of the Belgian State Railways and added a tapered barrel to improve circulation of water between the barrel and the firebox legs. He designed valves with a longer stroke and a greater lap than usual, to achieve full opening to exhaust. Passenger-train weights had been increasing rapidly, and Churchward produced his first 4–6– 0 express locomotive in 1902. However, he was still developing the details—he had a flair for selecting good engineering practices—and to aid his development work Churchward installed at Swindon in 1904 a stationary testing plant for locomotives. This was the first of its kind in Britain and was based on the work of Professor W.F.M.Goss, who had installed the first such plant at Purdue University, USA, in 1891. For comparison with his own locomotives Churchward obtained from France three 4–4–2 compound locomotives of the type developed by A. de Glehn and G. du Bousquet. He decided against compounding, but he did perpetuate many of the details of the French locomotives, notably the divided drive between the first and second pairs of driving wheels, when he introduced his four-cylinder 4–6–0 (the Star class) in 1907. He built a lone 4–6–2, the Great Bear, in 1908: the wheel arrangement enabled it to have a wide firebox, but the type was not perpetuated because Welsh coal suited narrow grates and 4–6–0 locomotives were adequate for the traffic. After Churchward retired in 1921 his successor, C.B.Collett, was to enlarge the Star class into the Castle class and then the King class, both 4–6–0s, which lasted almost as long as steam locomotives survived in service. In Church ward's time, however, the Great Western Railway was the first in Britain to adopt six-coupled locomotives on a large scale for passenger trains in place of four-coupled locomotives. The 4–6–0 classes, however, were but the most celebrated of a whole range of standard locomotives of advanced design for all types of traffic and shared between them many standardized components, particularly boilers, cylinders and valve gear.

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See also: Gresley, Sir Herbert Nigel; Stanier, Sir William Arthur

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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KF / JW

SUBJECT AREA: Aerospace, Steam and internal combustion engines

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Griffith was very much a "boffin", for he was a quiet, thoughtful man who shunned public appearances, yet he produced many revolutionary ideas. During the First World War he worked at the Royal Aircraft Factory, Farnborough, where he carried out research into structural analysis. Because of his use of soap films in solving torsion problems, he was nicknamed "Soap-bubble".

During the 1920s Griffith carried out research into gas-turbine design at the Royal Aircraft Establishment (RAE; as the Royal Aircraft Factory had become). In 1929 he made proposals for a gas turbine driving a propeller (a turboprop), but the idea was shelved. In the 1930s he was head of the Engine Department of the RAE and developed multi-stage axial compressors, which were later used in jet engines. This work attracted the attention of E.W. (later Lord) Hives of Rolls-Royce who persuaded Griffith to join Rolls-Royce in 1939. His first major project was a "contra-flow" jet engine, which was a good idea but a practical failure. However, Griffith's axial-flow compressor experience played an important part in the success of Rolls-Royce jet engines from the Avon onwards. He also proposed the bypass principle used for the Conway.

Griffith experimented with suction to control the boundary layer on wings, but his main interest in the 1950s centred on vertical-take-off and -landing aircraft. He developed the remarkable "flying bedstead", which consisted of a framework (the bedstead) in which two jet engines were mounted with their jets pointing downwards, thus lifting the machine vertically. It first flew in 1954 and provided much valuable data. The Short SC1 aircraft followed, with four small jets providing lift for vertical take-off and one conventional jet to provide forward propulsion. This flew successfully in the late 1950s and early 1960s. Griffith proposed an airliner with lifting engines, but the weight of the lifting engines when not in use would have been a serious handicap. He retired in 1960.

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SUBJECT AREA: Photography, film and optics

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Edwin Land's career began when, as a Harvard undergraduate in the late 1920s, he became interested in the possibility of developing a polarizing filter in the form of a thin sheet, to replace the crystal and stacked-glass devices then in use, which were expensive, cumbersome and limited in size. He succeeded in creating a material in which minute anisotropic iodine crystals were oriented in line, producing an efficient polarizer that was patented in 1929. After presenting the result of his researches in a Physics Department colloquium at Harvard, he left to form a partnership with George Wheelwright to manufacture the new material, which was seen to have applications as diverse as anti-glare car headlights, sunglasses, and viewing filters for stereoscopic photographs and films. In 1937 he founded the Polaroid Corporation and developed the Vectograph process, in which self-polarized photographic images could be printed, giving a stereoscopic image when viewed through polarizing viewers. Land's most significant invention, the instant picture, was stimulated by his three-year-old daughter. As he took a snapshot of her, she asked why she could not see the picture at once. He began to research the possibility, and on 21 February 1947 he demonstrated a system of one-step photography at a meeting of the Optical Society of America. Using the principle of diffusion transfer of the image, it produced a photograph in one minute. The Polaroid Land camera was launched on 26 November 1948. The original sepia-coloured images were soon replaced by black and white and, in 1963, by Polacolor instant colour film. The original peel-apart "wet" process was superseded in 1972 with the introduction of the SX-70 camera with dry picture units which developed in the light. The instant colour movie system Polavision, introduced in 1978, was less successful and was one of his few commercial failures.

Land died in March 1991, after a career in which he had been honoured by countless scien-tific and academic bodies and had received the Medal of Freedom, the highest civilian honour in America.

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SUBJECT AREA: Metallurgy

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The son of a distinguished engineer, Le Chatelier entered the Ecole Polytechnique in 1869: after graduating in the Faculty of Mines, he was appointed Professor at the Ecole Supérieure des Mines in 1877. After assisting Deville with the purification of bauxite in unsuccessful attempts to obtain aluminium in useful quantities, Le Chatelier's work covered a wide range of topics and he gave much attention to the driving forces of chemical reactions. Between 1879 and 1882 he studied the mechanisms of explosions in mines, and his doctorate in 1882 was concerned with the chemistry and properties of hydraulic cements. The dehydration of such materials was studied by thermal analysis and dilatometry. Accurate temperature measurement was crucial and his work on the stability of thermocouples, begun in 1886, soon established the superiority of rhodium-platinum alloys for high-temperature measurement. The most stable combination, pure platinum coupled with a 10 per cent rhodium platinum positive limb, became known as Le Chatelier couple and was in general use throughout the industrial world until c. 1922. For applications where thermocouples could not be used, Le Chatelier also developed the first practical optical pyrometer. From hydraulic cements he moved on to refractory and other ceramic materials which were also studied by thermal analysis and dilatometry. By 1888 he was systematically applying such techniques to metals and alloys. Le Chatelier, together with Osmond, Worth, Genet and Charpy, was a leading member of that group of French investigators who established the new science of physical metallurgy between 1888 and 1900. Le Chatelier was determining the recalescence points in steels in 1888 and was among the first to study intermetallic compounds in a systematic manner. To facilitate such work he introduced the inverted microscope, upon which metallographers still depend for the routine examination of polished and etched metallurgical specimens under incident light. The principle of mobile equilibrium, developed independently by Le Chatelier in 1885 and F.Braun in 1886, stated that if one parameter in an equilibrium situation changed, the equilibrium point of the system would move in a direction which tended to reduce the effect of this change. This provided a useful qualitative working tool for the experimentalists, and was soon used with great effect by Haber in his work on the synthesis of ammonia.

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SUBJECT AREA: Electricity, Electronics and information technology, Photography, film and optics

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Paul was educated at the City of London School and Finsbury Technical College. He worked first for a short time in the Bell Telephone Works in Antwerp, Belgium, and then in the electrical instrument shop of Elliott Brothers in the Strand until 1891, when he opened an instrument-making business at 44 Hatton Garden, London. He specialized in the design and manufacture of electrical instruments, including the Ayrton Mather galvanometer. In 1902, with a purpose-built factory, he began large batch production of his instruments. He also opened a factory in New York, where uncalibrated instruments from England were calibrated for American customers. In 1903 Paul introduced the Unipivot galvanometer, in which the coil was supported at the centre of gravity of the moving system on a single pivot. The pivotal friction was less than in a conventional instrument and could be used without accurate levelling, the sensitivity being far beyond that of any pivoted galvanometer then in existence.

In 1894 Paul was asked by two entrepreneurs to make copies of Edison's kinetoscope, the pioneering peep-show moving-picture viewer, which had just arrived in London. Discovering that Edison had omitted to patent the machine in England, and observing that there was considerable demand for the machine from show-people, he began production, making six before the end of the year. Altogether, he made about sixty-six units, some of which were exported. Although Edison's machine was not patented, his films were certainly copyrighted, so Paul now needed a cinematographic camera to make new subjects for his customers. Early in 1895 he came into contact with Birt Acres, who was also working on the design of a movie camera. Acres's design was somewhat impractical, but Paul constructed a working model with which Acres filmed the Oxford and Cambridge Boat Race on 30 March, and the Derby at Epsom on 29 May. Paul was unhappy with the inefficient design, and developed a new intermittent mechanism based on the principle of the Maltese cross. Despite having signed a ten-year agreement with Paul, Acres split with him on 12 July 1895, after having unilaterally patented their original camera design on 27 May. By the early weeks of 1896, Paul had developed a projector mechanism that also used the Maltese cross and which he demonstrated at the Finsbury Technical College on 20 February 1896. His Theatrograph was intended for sale, and was shown in a number of venues in London during March, notably at the Alhambra Theatre in Leicester Square. There the renamed Animatographe was used to show, among other subjects, the Derby of 1896, which was won by the Prince of Wales's horse "Persimmon" and the film of which was shown the next day to enthusiastic crowds. The production of films turned out to be quite profitable: in the first year of the business, from March 1896, Paul made a net profit of £12,838 on a capital outlay of about £1,000. By the end of the year there were at least five shows running in London that were using Paul's projectors and screening films made by him or his staff.

Paul played a major part in establishing the film business in England through his readiness to sell apparatus at a time when most of his rivals reserved their equipment for sole exploitation. He went on to become a leading producer of films, specializing in trick effects, many of which he pioneered. He was affectionately known in the trade as "Daddy Paul", truly considered to be the "father" of the British film industry. He continued to appreciate fully the possibilities of cinematography for scientific work, and in collaboration with Professor Silvanus P.Thompson films were made to illustrate various phenomena to students.

Paul ended his involvement with film making in 1910 to concentrate on his instrument business; on his retirement in 1920, this was amalgamated with the Cambridge Instrument Company. In his will he left shares valued at over £100,000 to form the R.W.Paul Instrument Fund, to be administered by the Institution of Electrical Engineers, of which he had been a member since 1887. The fund was to provide instruments of an unusual nature to assist physical research.

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SUBJECT AREA: Aerospace

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Auguste Piccard and his twin brother, Jean-Félix, studied together in Zurich and qualified as a physicist and a chemist, respectively. In 1913 they made a sixteen-hour balloon flight together, and in 1915 they joined the balloon section of the Swiss Army. Auguste moved to Brussels as Professor of Applied Physics in 1922 and he carried out research into cosmic radiation. He realized that he needed to ascend into the rarefied air of the stratosphere in order to study these cosmic rays. His target was 16,000 m (52,500 ft), but no one had ever ventured to this height before.

Not surprisingly, Auguste Piccard turned to a balloon for his experiments, and during 1930 he designed a hydrogen balloon with a spherical gondola to house the crew. This gondola was sealed and pressurized with air, just as a modern airliner has a pressurized cabin. With Belgian finance, Piccard was able to build his balloon, and on 27 May 1931 he and his colleague Paul Kipfer reached a height of 15,781 m (51,775 ft). Although this was a world record and created great public interest, Piccard was a scientist rather than a record breaker, and as he needed further information he prepared for another ascent. His new gondola was equipped with radio and improved scientific equipment. On 18 August 1932 it ascended from Zurich and reached a height of 16,201 m (53,152 ft).

Jean-Félix was also interested in high-altitude balloon flights and in 1934, together with his wife, he ascended through a clouded sky and reached 17,550m (57,579ft). Jean- Félix also tested a gondola lifted by ninety-eight small balloons, and he developed frost-resistant windows. Other balloonists followed with record-breaking high-altitude flights, but Auguste Piccard, aided by his son Jacques, turned his attention to exploration of the depths of the ocean.

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SUBJECT AREA: Broadcasting, Electronics and information technology, Recording

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Poniatoff was educated at the University of Kazan, the Imperial College in Moscow, and the Technische Hochschule in Karlsruhe, gaining degrees in mechanical and electrical engineering. He was in Germany when the First World War broke out, but he managed to escape back to Russia, where he served as an Air Force pilot with the Imperial Russian Navy. During the Russian Revolution he was a pilot with the White Russian Forces, and escaped into China in 1920; there he found work as an assistant engineer in the Shanghai Power Company. In 1927 he immigrated to the USA, becoming a US citizen in 1932. He obtained a post in the research and development department of the General Electric Company in Schenectady, New York, and later at Dalmo Victor, San Carlos, California. During the Second World War he was involved in the development of airborne radar for the US Navy.

In 1944, taking his initials to form the title, Poniatoff founded the AMPEX Corporation to manufacture components for the airborne radar developed at General Electric, but in 1946 he turned to the production of audio tape recorders developed from the German wartime Telefunken Magnetophon machine (the first tape recorder in the truest sense). In this he was supported by the entertainer Bing Crosby, who needed high-quality replay facilities for broadcasting purposes, and in 1947 he was able to offer a professional-quality product and the business prospered.

With the rapid post-war boom in television broadcasting in the USA, a need soon arose for a video recorder to provide "time-shifting" of live TV programmes between the different US time zones. Many companies therefore endeavoured to produce a video tape recorder (VTR) using the same single-track, fixed-head, longitudinal-scan system used for audio, but the very much higher bandwidth required involved an unacceptably high tape-speed. AMPEX attempted to solve the problem by using twelve parallel tracks and a machine was demonstrated in 1952, but it proved unsatisfactory.

The development team, which included Charles Ginsburg and Ray Dolby, then devised a four-head transverse-scan system in which a quadruplex head rotating at 14,400 rpm was made to scan across the width of a 2 in. (5 cm) tape with a tape-to-head speed of the order of 160 ft/sec (about 110 mph; 49 m/sec or 176 km/h) but with a longitudinal tape speed of only 15 in./sec (0.38 m/sec). In this way, acceptable picture quality was obtained with an acceptable tape consumption. Following a public demonstration on 14 April 1956, commercial produc-tion of studio-quality machines began to revolutionize the production and distribution of TV programmes, and the perfecting of time-base correctors which could stabilize the signal timing to a few nanoseconds made colour VTRs a practical proposition. However, AMPEX did not rest on its laurels and in the face of emerging competition from helical scan machines, where the tracks are laid diagonally on the tape, the company was able to demonstrate its own helical machine in 1957. Another development was the Videofile system, in which 250,000 pages of facsimile could be recorded on a single tape, offering a new means of archiving information. By 1986, quadruplex VTRs were obsolete, but Poniatoff's role in making television recording possible deserves a place in history.

Poniatoff was President of AMPEX Corporation until 1955 and then became Chairman of the Board, a position he held until 1970.

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