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Файл:Великие ученые и изобретатели = Great Scientists and Inventors. Учебное пособие
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UNIT IV
HARRY NYQUIST (1889–1976)
AND HENDRIK BODE (1905–1982):
FROM NETWORKS AND NOISE TO
NASA
1. Прочитайте английские слова и назовите их русские эквива-
ленты. Просмотрите текст. Выполните упражнения после текста.
1) network
2) contribution
3) amplifier
4) breakthrough
5) feedback amplifier
6) electrical engineering
7) transmission technique
8) behavior
9) distortion
10) provide
11) acquire
12) enormous
13) achieve
14) condition
15) prevent from
16) valve amplifier
17) transistor amplifier
18) long distance communication
19) improvement
20) result in
21) anti-aircraft missile
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Text
The names of Harry Nyquist and Hendrik Wade Bode go together like
peaches and cream and are often paired in textbooks dealing with the theory of
stability in linear networks. They worked through a period which might well be
regarded as the classical period of network analysis and synthesis in telecommunications design.
Harry Nyquist was born at Nilsby in Sweden, on 7 February 1889. When
he died in 1976, at the age of 87, he was survived in Sweden by two sisters and
a brother, the brother still living at Nilby.
Emigration to the United States beckoned and at the age of eighteen he settled in Minnesota, west of the Great Lakes, where he worked for a time as a
school teacher. He entered university education late, graduating from the University of Dakota at the age of 26 with a degree in electrical engineering. He
followed that with a Master’s degree the next year and transferred to Yale University, where he received his Ph. D. in 1917.
He spent 37 years in the Bell System until his retirement in 1954 and received 138 Americans patents, averaging nearly one every three months and
gaining a reputation for providing inventions almost to order.
His contributions to the field of communications include the first quantitative description of thermal (Johnson) noise, signal- transmission studies which
helped lay the foundation for information theory and data communications, the
invention of vestigial-sideband transmission and the famous Nyquist stability
criterion, which has been used outside electronics as well as within it- to describe the way in which someone drives a car, for example.
Nyquist’s first major contribution to transmission to techniques was a series of theoretical studies of the behaviour of analogue and digital signals in
transmission systems, beginning in 1924.
Nyquist and Bode are best known for their work on stability criteria. Harry
Black’s 1927 invention of the negative-feedback amplifier solved the enormous
problem of how to reduce the distortion within an amplifier almost to the point
of elimination.
Black’s success raised other problems for, despite his desires, the amplifiers did have a tendency to become unstable and oscillate. As mathematical
22
physicists, Nyquist and Bode were two of the men chiefly responsible for the
derivation of the mathematical theory that enabled the systematic design of stable feed-back amplifiers to take place.
Bode was born in Madison, Wisconsin, on Christmas Eve 1905. After
schooling in Illinois and Arizona he attended Ohio State University and gradu-
ated with a degree 1924 and a Master’s degree in 1926, whereupon he joined
the year-old Bell Laboratories. He was soon at work on the design of electrical
filters, but in 1929 he transferred to the Mathematical Research Group where he
specialized in electrical network theory and its application to the problems of
long- distance communications. Twenty three years later he became Director of
Mathematical Research, subsequently becoming Director of the Physical Sciences and, in 1958, a vice president of Bell Labs overseeing military systems
engineering. On the way he received a Ph. D. from Columbia University in 1935.
Bode’s contribution to feedback- amplifier design began, according to his
own recollections, with a study of equalizing circuits whose function was to
provide automatic compensation for temperature and other variations in transmission lines.
During World War II, Bode applied electronics (in place of or in conjunction with mechanics) to the problems of anti-air-aircraft gun control. This resulted in a model T-15 gun director which, though it appeared superior to existing equipment in trails, was not placed in production. Later Bode and W. A. MacNair directed research and development of anti-aircraft missiles. In 1946 Bode
received a Presidential Certificate of Merit of Merit for his wartime contributions.
In February 1945 Bode was one of five men asked to form a team to study
the possibilities for a guided missile capable of shooting down future aircraft
flying at heights and speeds beyond the capabilities of conventional gunfire. In
just five months, the group produced report which was later to be regarded as a
classic for its thoroughness and insight.
Bode completed his career with Bell as special adviser and member of the
Board of Bellcomm, a company formed by Bell as a small part of the NASA effort for “landing the man on the Moon and returning him safely to Earth”, as
President Kennedy expressed it in 1961. Then in October 1967, aged 61, Hen-
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dric Bode retired from Bell Labs after 41 years service to take up a second career as the Professor of Systems Engineering at Harvard University. There he
directed graduate research and taught a course on the planning and implementation of engineering and development programmes. He finally retired, for the second time, as professor emeritus in 1974.
2. Просмотрите текст. Найдите ответы на следующие вопросы:
1. Why do the names of Harry Nyquist and Hendrik Wade Bode go together?
2. Where and when was Harry Nyquist born?
3. Where did Nyquist study?
4. What field of science did Nyquist make contribution to?
5. What work made Nyquist and Bode famous?
6. When and where was Hendrik Wade Bode born?
7. Where did Bode study?
8. What problems did Bode apply electronics to during World War II?
9. What project did Bode take part in?
10. What was Bode’s second career?
3. Определите грамматические явления в предложениях и объяс-
ните их.
1. When he died in 1976, at the age of 87, he was survived in Sweden by
two sisters and a brother, the brother still living at Nilsby.
2. Black’s success raised other problems for, despite his desires, the ampli-
fiers did have a tendency to become unstable and oscillate.
3. Bode’s contribution to feedback-amplifier design, began, according to
his own recollections, with a study of equalizing circuits whose function was to
provide automatic compensation for temperature and other variations in transmission lines.
4. Просмотрите текст. Укажите, являются ли предложения верным или неверными. Докажите, используя информацию из текста.
1. Nyquist and Bode dealt with theory of stability in linear networks.
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2. Nyquist and Bode worked through the classical period of network anal-
yses and synthesis in telecommunications design.
3. Nyquist graduated from the University of North Dakota at the age of 26
with a degree in radio engineering.
4. Nyquist received 137 American Patents.
5. Nyquist provided definitions for two types of distortion.
6. Bode’s contribution to feedback-amplifier design began, according to
his own recollections, with a study of equalizing circuits.
7. In 1947 Bode received a Presidential Certificate of Merit for his wartime
contributions.
8. Bode completed his career with Bell as special advisor and member of
the Board of Bellcom, a company formed by Bell as a small part of the NASA
effort for “landing a man on the Moon and returning him safely to Earth”, as
president Kennedy expressed it in 1962.
9. At Harvard University Bode directed graduate research.
10. At Harvard University Bode taught a course on the planning and implementation of economic and development programmes.
5. Используйте следующие темы для обсуждения в виде диалогов
или монологов:
1. Harry Nyquist and Hendrik Bode: from networks and noise to NASA.
2. Nyquist and Bode are best known for their work on stability criteria.
3. The famous Nike missile, named after a mythological Greek winged
goddess of victory.
It is interesting to know:
As with most pioneers of their caliber, both Nyquist and Bode deserved
and received honours. Nyquist was awarded medals by the Franklin Institute
and the Institute of Radio Engineers, Bode the Edison Medal of the IEEE.
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UNIT V
JOHN AMBROSE FLEMING:
THE BIRTH OF ELECTRONICS
(1849–1945)
1. Прочитайте английские слова и назовите их русские эквива-
ленты. Просмотрите текст. Выполните упражнения после текста.
1) oscillation valve
2) thermionic diode
3) worldwide
4) incandescent light bulb
5) wire
6) connect
7) filament
8) detect
9) current
10) cathode rays
11) experience
12) contribution
13) average
14) speculate
15) achievement
Text
You probably would not think of building a radio detector from a light
bulb, but that is what Ambrose Fleming did in 1904.The result was what he
called the “oscillation valve”, now better known as the thermionic diode. It was
only two years later when Lee de Forest added a third electrode to make the
first primitive triode. These two classic inventions led a fight between the two
inventors, but they also led to the now-vast, worldwide industry we call electronics.
26
The story begins with that great American inventor, Thomas Edison. In
1883, he probed inside an incandescent light bulb, first with a wire and then
with a metal plate. He found that if this electrode was connected to the positive
end of the filament via a galvanometer then a current was detected. If it was
connected to the negative end, no current flowed. A little later, using a separate
battery in the plate or anode circuit, J. Elster and H. Geitel showed the unidirectional nature of the current flow.
This “Edison effect” was studied by many people over the following 20
years, particularly to examine thermionic emission.
Fleming’s real invention was the use he found for the established Edison
effect as a rectifier of high frequency oscillations. Edison kicked himself when
he realized the opportunity he had missed, even though he held what is now
seen as the first patent in electronics – the effect used as the voltage indicator
(1884).
Fleming’s career, meanwhile, had progressed over those 20 years. In 1886
he experimented with methods of focusing the cathode rays and three years lat-
er he was appointed scientific advisor to the Marconi’s Wireless Telegraph
Company. In this role he specified equipment for the famous transatlantic signal
transmission in 1901. He had also gained extensive experience of consultancy,
to the National Telephone Company and the Ediswan Electric Light Company.
With all this highly relevant experience he was in an ideal position from which
to make his famous contribution to electronics.
It was in October 1904 that Fleming had what he described as “a sudden,
very happy thought.” Telephones and meters were too slow to register the posi-
tive-negative cycling of a high frequency radio signal and therefore only indicated the average value, which was zero. Knowing that a light bulb with a hot
filament and an insulated plate sealed within it would only pass current in one
direction, he speculated that it might act as a rectifier for the high-frequency
currents. He asked his assistant, G. B. Dyke, to test the idea – and it worked.
The next month he wrote to Marconi, “I have been receiving signals on an aerial with nothing but a mirror galvanometer and my device.”
It would be nice to think that Fleming made his fortune from this pivotal
invention, but it brought him relatively little joy. Marconi’s held the patent, and
27
manufactured and used some diodes. But in this early form they were no panacea for all radio detection problems and they played only a small part in the early years of radio.
John Ambrose Fleming was born at Lancaster on 29 November, 1849, the
oldest of the seven children of a Congregational minister. His father, he said,
was descended from “a long line of Scotch ancestors of Flemish origin.” His
mother’s family came from Swanscombe in Kent and they were pioneers of the
manufacture of Portland cement.
In 1854 his parents moved to London where Fleming was to spend almost
70 years of his life. When he finally retired at 77, after an action- packed working life, he moved to the seaside, to Sidmouth, where he enjoyed nearly another
20 years before his death on 18 April, 1945. He married twice but had no children. His first wife, Clara Ripley, died in 1917 but his second, Olive Franks,
whom he married in 1933, survived him.
Fleming started school at about the age of ten, attending a private school
where he particularly enjoyed geometry. Prior to that his mother tutored him,
and he had learned virtually by heart, a book called the “The Child’s Guide to
Knowledge,” a popular book of the day – even as an adult he could quote from
it. His schooling continued at the University College School where, although
accomplished at maths, he habitually came bottom of the class at Latin.
Even as a boy he wanted to become an engineer. At 11 he had his own
workshop where he built model boats and engines. He even built his own camera, the start of a lifelong interest in photography. Training to become an engineer was beyond the family’s financial resources but he reached his goal via a
route which alternated education with work.
He enrolled for a BSc degree at University College, London, in the mid1860s and studied under the mathematician A. Carey Foster. After two years he
left because of a shortage of money and took a job with a shipbuilder in Dublin.
The work was so dull that he quit after a few months and found work with a
stock jobbing firm on the London Stock Exchange.
For two months he earned his living in the financial world. Later, as a
teacher,, he preached that every boy and a girl should have some practical train-
ing in “the bulls, the bears and the stags of the Stock Exchange and their efforts
to make money out of the trustful and optimistic public.”
28
At the Stock Exchange his work finished at the early hour of 4 o’clock. So
it was not only about the bulls and bears that he learned, for he completed his
degree through evening study, graduating in 1870 with a first class degree.
For 18 months, from January 1871, he replenished his funds as a science
teacher at Rossall School before resigning to return to his studies, this time as a
student of chemistry at the Royal College of Science in South Kensington. It
was while there that he first studied the voltaic battery which became the subject of his first scientific paper. This turned out to be a unique honour, for it was
the first paper to be read to the new Physical Society of London and appears on
page one of their Proceedings.
His interests ranged widely over the years. At various times he specialized
in transformer tests (acting as consultant to Ferranti), standards and measurements, incandescent lamps and photometry, the effects of low temperatures on
the electrical resistance of metals (with Sir James Dewar), and (of course) thermionics. In his retirement he was for 15 years president of the Television Society of London.
2. Просмотрите текст. Найдите ответы на следующие вопросы:
1. What did Ambrose Fleming do in 1904 and what was the result?
2. What did Thomas Edison find?
3. What was Fleming’s real invention?
4. Why did Edison kick himself?
5. What did Fleming do in 1896?
6. What happened in October 1904?
7. When and where was Fleming born?
8. Where did he study?
9. What became the subject of Fleming’s first scientific paper?
10. Which two classic inventions led to electronics?
3. Определите грамматическое явление в предложениях и объяс-
ните его.
1. It was only ten years later when Lee de Forest added a third electrode to
make the first primitive triode.
2. It was in October 1904 that Fleming had what he described as “a sudden,
very happy thought”.
29
3. So it was not only about the bulls and bears that he learned, for he completed his degree through evening study, graduating in 1870 with a first class
degree.
4. It was while there that he first studied the voltaic battery which became
the subject of his first scientific paper.
4. Просмотрите текст. Укажите, являются ли предложения верными или неверными. Докажите, используя информацию из текста.
1. Fleming built a radio detector from a light bulb in 1904.
2. Thomas Edison found that if the electrode was connected to the negative
end of the filament via a galvanometer then a current was detected.
3. Fleming’s real invention was the use he found for the established Edison
effect as an amplifier of high-frequency oscillations.
4. In 1896 Fleming experimented with methods of cathode rays and three
years later he was appointed scientific adviser to the Marconi’s Wireless Telegraph Company.
5. Fleming’s invention made him happy.
6. At various times he specialized in cathode rays tests.
5. Используйте следующие темы для обсуждения в виде диалогов
или монологов:
1. “A sudden, very happy thought.”
2. Fleming proved himself as a brilliant scholar and a gifted teacher.
3. Fleming and the birth of electronics.
It is interesting to know:
John Ambrose Fleming received many honours, including the Followship
of the Royal Society in 1892, medals from scientific and engineering institutions and, in 1929, a knighthood.
He has been described as a born teacher and gave meticulously prepared
public lectures. Showmanship was not allowed into his lectures. Fleming was
also an accomplished photographer. In addition, he painted water colours and
enjoyed climbing in the Alps. His interests were not those which entailed much
socializing and he disliked organized games.
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