George Zames
Encyclopedia
George Zames was a control theorist and professor at McGill University
, Montreal
, Quebec
, Canada
. Zames is known for his fundamental contributions to the theory of robust control
, and was credited for the development of various well-known results such as small-gain theorem, passivity theorem, circle criterion
in input–output form, and most famously, H-infinity methods.
to a Jewish family. Growing up in Warsaw
, Zames and his family escaped the city at the onset of World War II
, and moved to Kobe
(Japan), through Lithuania
and Siberia
, and finally to the Anglo-French International Settlement in Shanghai
. Zames indicated later that he and his family owe their lives to the transit visa provided by the Japanese Consul to Lithuania, Senpo Sugihara. In Shanghai, Zames continued his schooling, and in 1948, the family emigrated to Canada
.
at the age of 15 and received a B.Eng. degree in Engineering Physics
. Graduating at the top of his class, Zames won an Athlone Fellowship to study in England
, and moved to the Imperial College. Graduating in two years, his advisors included Colin Cherry
, Dennis Gabor
, and John Hugh Westcott. In 1956, Zames entered the Massachusetts Institute of Technology
to start his doctoral studies, and in 1960 earned a Sc.D. for a thesis titled Nonlinear Operations of System Analysis. He was advised by Norbert Wiener
and Yuk-Wing Lee
.
. In 1965, Zames received a Guggenheim Fellowship
and moved to the NASA Electronic Research Center (ERC), where he founded the Office of Control Theory and Applications (OCTA). In 1969, it was announced that NASA ERC was to be closed, and Zames joined the newly established Department of Transportation
Research Center in 1970. In 1972, Zames spent a sabbatical at the Technion in Haifa, Israel, and in 1974, he returned to McGill University to become a professor and eventually the MacDonald Chair of Electrical Engineering until his death in 1997.
representation that dominated control theory for several decades. At the core of much of his work is the objective of complexity reduction through organization, for which Zames explained:
McGill University
Mohammed Fathy is a public research university located in Montreal, Quebec, Canada. The university bears the name of James McGill, a prominent Montreal merchant from Glasgow, Scotland, whose bequest formed the beginning of the university...
, Montreal
Montreal
Montreal is a city in Canada. It is the largest city in the province of Quebec, the second-largest city in Canada and the seventh largest in North America...
, Quebec
Quebec
Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
. Zames is known for his fundamental contributions to the theory of robust control
Robust control
Robust control is a branch of control theory that explicitly deals with uncertainty in its approach to controller design. Robust control methods are designed to function properly so long as uncertain parameters or disturbances are within some set...
, and was credited for the development of various well-known results such as small-gain theorem, passivity theorem, circle criterion
Circle criterion
In nonlinear control, the circle criterion is an important theorem in showing the stability of nonlinear time-varying systems. It can be viewed as a generalization of the Nyquist stability criterion for LTI systems.-Overview:...
in input–output form, and most famously, H-infinity methods.
Childhood
George Zames was born on January 7, 1934 in Łódź, PolandPoland
Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
to a Jewish family. Growing up in Warsaw
Warsaw
Warsaw is the capital and largest city of Poland. It is located on the Vistula River, roughly from the Baltic Sea and from the Carpathian Mountains. Its population in 2010 was estimated at 1,716,855 residents with a greater metropolitan area of 2,631,902 residents, making Warsaw the 10th most...
, Zames and his family escaped the city at the onset of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, and moved to Kobe
Kobe
, pronounced , is the fifth-largest city in Japan and is the capital city of Hyōgo Prefecture on the southern side of the main island of Honshū, approximately west of Osaka...
(Japan), through Lithuania
Lithuania
Lithuania , officially the Republic of Lithuania is a country in Northern Europe, the biggest of the three Baltic states. It is situated along the southeastern shore of the Baltic Sea, whereby to the west lie Sweden and Denmark...
and Siberia
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...
, and finally to the Anglo-French International Settlement in Shanghai
Shanghai
Shanghai is the largest city by population in China and the largest city proper in the world. It is one of the four province-level municipalities in the People's Republic of China, with a total population of over 23 million as of 2010...
. Zames indicated later that he and his family owe their lives to the transit visa provided by the Japanese Consul to Lithuania, Senpo Sugihara. In Shanghai, Zames continued his schooling, and in 1948, the family emigrated to Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
.
Education
Zames entered McGill UniversityMcGill University
Mohammed Fathy is a public research university located in Montreal, Quebec, Canada. The university bears the name of James McGill, a prominent Montreal merchant from Glasgow, Scotland, whose bequest formed the beginning of the university...
at the age of 15 and received a B.Eng. degree in Engineering Physics
Engineering physics
Engineering physics is the study of the combined disciplines of physics, engineering and mathematics in order to develop an understanding of the interrelationships of these three disciplines. Fundamental physics is combined with problem solving and engineering skills, which then has broad...
. Graduating at the top of his class, Zames won an Athlone Fellowship to study in England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
, and moved to the Imperial College. Graduating in two years, his advisors included Colin Cherry
Colin Cherry
Edward Colin Cherry was a British cognitive scientist whose main contributions were in focused auditory attention, specifically regarding the cocktail party problem. This concerns the problem of following only one conversation while many other conversations are going on around us...
, Dennis Gabor
Dennis Gabor
Dennis Gabor CBE, FRS was a Hungarian-British electrical engineer and inventor, most notable for inventing holography, for which he later received the 1971 Nobel Prize in Physics....
, and John Hugh Westcott. In 1956, Zames entered the Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
to start his doctoral studies, and in 1960 earned a Sc.D. for a thesis titled Nonlinear Operations of System Analysis. He was advised by Norbert Wiener
Norbert Wiener
Norbert Wiener was an American mathematician.A famous child prodigy, Wiener later became an early researcher in stochastic and noise processes, contributing work relevant to electronic engineering, electronic communication, and control systems.Wiener is regarded as the originator of cybernetics, a...
and Yuk-Wing Lee
Yuk-Wing Lee
Yuk-Wing Lee was a Professor of Electrical Engineering at the Massachusetts Institute of Technology. He is best known for adapting and popularizing the pioneering work of Norbert Wiener and for his own research on statistical communication theory. John Costas and Amar Bose were his students at MIT....
.
Career
From 1960 to 1965, Zames held various teaching positions at MIT and Harvard UniversityHarvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
. In 1965, Zames received a Guggenheim Fellowship
Guggenheim Fellowship
Guggenheim Fellowships are American grants that have been awarded annually since 1925 by the John Simon Guggenheim Memorial Foundation to those "who have demonstrated exceptional capacity for productive scholarship or exceptional creative ability in the arts." Each year, the foundation makes...
and moved to the NASA Electronic Research Center (ERC), where he founded the Office of Control Theory and Applications (OCTA). In 1969, it was announced that NASA ERC was to be closed, and Zames joined the newly established Department of Transportation
Department of Transportation
The Department of Transportation is the most common name for a government agency in North America devoted to transportation. The largest is the United States Department of Transportation, which oversees interstate travel. All U.S. states, Canadian provinces, and many local agencies also have...
Research Center in 1970. In 1972, Zames spent a sabbatical at the Technion in Haifa, Israel, and in 1974, he returned to McGill University to become a professor and eventually the MacDonald Chair of Electrical Engineering until his death in 1997.
Family
Zames was married to Eva, whom he met in Israel. They have two sons, Ethan and Jonathan.Research
Zames’s research focused on imprecisely modelled systems using the input-output method, an approach that is distinct from the state spaceState space (controls)
In control engineering, a state space representation is a mathematical model of a physical system as a set of input, output and state variables related by first-order differential equations...
representation that dominated control theory for several decades. At the core of much of his work is the objective of complexity reduction through organization, for which Zames explained:
For the purposes of control design, gross qualitative properties such as robustness can be analyzed and predicted without depending on accurate models or syntheses. Mathematical analysis provides topological tools that are very well suited for this purpose, such as compactness, contraction, and fixed-point methods. Furthermore, in control design, where there is lots of model uncertainty, it is often more important to be able to gauge qualitative behaviour (robustness, stability, existence of oscillations) than to compute exactly.
Legacy
The International Journal of Robust and Nonlinear Control published in 2000 a special issue in George Zames’s honour, including a complete list of his publications. Reviews of Zames’s life and legacy were published by S. Mitter and A. Tennenbaum, J. C. Willems, and in a volume resulting from a conference held to honor the occasion of Zames's 60th birthday.Awards and honors
- In 1980 the Rufus Oldenburger MedalRufus Oldenburger MedalThe Rufus Oldenburger Medal is an award given by the American Society of Mechanical Engineers recognizing significant contributions and outstanding achievements in the field of automatic control. It was established in 1968 in the honor of Rufus Oldenburger....
from the American Society of Mechanical EngineersAmerican Society of Mechanical EngineersThe American Society of Mechanical Engineers is a professional body, specifically an engineering society, focused on mechanical engineering.... - In 1984 the IEEE Control Systems Science and Engineering Award
- In 1995 the Killam Prize