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Hendrik Wade Bode (pronounced Boh-dee in English, Boh-dah in Dutch), (24 December 1905 – 21 June, 1982) was an American engineer, researcher, inventor, author and scientist, of Dutch ancestry. As a pioneer of modern control theory and electronic telecommunications he revolutionized both the content and methodology of his chosen fields of research.

In addition, his research impacted many other engineering disciplines and laid the foundation for a diverse array of modern innovations such as computers, robots and mobile phones among others.

Long respected in academic circles worldwide, he is also widely known to modern engineering students mainly for developing the asymptotic magnitude and phase plot that bears his name, the Bode plot.

His research contributions in particular were not only multidimensional but far reaching as well, extending as far as the U.S. space program.

Immediately after graduation from high school he applied for admission to the University of Illinois but was denied because of his age. Decades later, in 1977, the same University would grant him an Honorary Sc.D. Degree.

He eventually applied and was accepted at Ohio State University, where his father also taught, and he received his B.A. degree in 1924, at age 19, and his M.A. Degree in 1926, both in Mathematics. After receiving his M.A. he remained at his alma mater, working as a teaching assistant, for an additional year.

In 1938 he developed his asymptotic phase and magnitude plots. His work on Automatic (Feedback) Control Systems introduced innovative methods to the study of system stability, that enabled engineers to investigate time domain stability using the frequency domain concepts of gain and phase margin, the study of which was aided by his now famous plots. In essence, his method made stability transparent to both the time and frequency domains and, furthermore his frequency domain-based analysis was much faster and simpler than the traditional time domain-based method. This provided engineers with a fast and intuitive stability analysis and system design tool that is as popular today as it was groundbreaking then.

NDRC, the funding agency of this project, was operating under the aegis of the Office of Scientific Research and Development (OSRD).

His NDRC funded research at Bell Labs under the section D-2 (Control Systems section) contract eventually led to other important developments in related fields and laid the cornerstone for many present day inventions. In the field of control theory, for example, it aided in the further development of servomechanism design and control, a crucial component of modern robotics. The development of Wireless Data Communications theory by Bode led to later inventions such as mobile phones and wireless networking.

The reason for the new project was that Director T-10 encountered difficulties in calculating the target velocity by differentiating the target position. Due to discontinuities, variations and noise in the radar signal the position derivatives sometimes fluctuated wildly and this caused erratic motion in the servomechanisms of the gun because their control signal was based on the value of the derivatives. This could be mitigated by smoothing or averaging out the data but this caused delays in the feedback loop that enabled the target to escape. As well the algorithms of Director T-10 required a number of transformations from cartesian (rectangular) to polar coordinates and back to Cartesian, a process that introduced additional tracking errors.

Bode designed the velocity computing networks of Director T-15 by applying a finite difference method instead of differentiation. Under this scheme the target positional coordinates were stored in a mechanical memory usually a potentiometer or a cam. The velocity was then calculated by taking the difference between the coordinates of the current position and the coordinates of the previous reading that were stored in memory and dividing by the difference of their respective times. This method was more robust than the differentiation method and it also smoothed out signal disturbances since the finite time step size was less sensitive to random signal impulses (spikes). It also introduced for the first time an algorithm better suited to modern digital signal processing theory rather than to the classical Calculus based analog signal processing approach that was followed then. Not coincidentally it is an integral part of modern digital control theory and digital signal processing and it is known as the backward difference algorithm. In addition the Director T-15 operated only in rectangular coordinates thus eliminating coordinate transformation based errors. These design innovations paid performance dividends and the Director T-15 was twice as accurate as its predecessor and it converged on a target twice as fast.

The fire control algorithm implementation of his artillery design research and his extensive work with feedback amplifiers advanced the state of the art in computational methods and led to the eventual development of the electronic analog computer, the operational amplifier based forefather of today's digital computers.

Inventions such as these, ironically, given their military research origins, have had a profound and lasting impact in the civilian domain and have forever altered its landscape.

Bode's work on Electronic Communications, especially on filter and equalizer design, continued during this time and in 1945 it culminated in the publication of his book under the title of Network Analysis and Feedback Amplifier Design, that is considered a classic in the field of electronic telecommunications and was extensively used as a textbook for many graduate programs at various universities as well as for internal training courses at Bell Labs. He was also the prolific author of many research papers that were published in prestigious scientific and technical journals.

His applied research at Bell Labs over the years led to numerous patented inventions, some of which were registered in his name. By the time of his retirement he held a total of 25 patents in various areas of electrical and communications engineering, including signal amplifiers and artillery control systems.

He retired from Bell Labs in October 1967, at the age of 61, ending an association that spanned more than four decades and changed the face of many of the core elements of Modern Engineering.

During his tenure there, he pursued research on military decision making algorithms and optimization techniques based on stochastic processes that are considered a precursor of modern fuzzy logic. He also studied the effects of technology on modern society and taught courses on the same subject at Harvard's Science and Public Policy Seminar, while supervising and teaching graduate students at the same time in the division of Engineering and Applied Physics.

In 1974 he retired for the second time and Harvard awarded him the honorary position of Professor Emeritus. He, nevertheless, kept his office at Harvard and continued working from there, mainly as an advisor to government on policy matters.

In 1975 ASME awarded him the Rufus Oldenberger Award and in 1979 he became the first recipient of the Control Heritage Award from the American Automatic Control Council.

In 1979 he received the Richard E. Bellman Control Heritage Award at its inaugural year. The award is given to researchers with distinguished career contributions to the theory or applications of automatic control, and it is the highest recognition of professional achievement for US control systems engineers and scientists.

Posthumously, in 1989, the IEEE Control Systems Society established the Hendrik W. Bode Lecture Prize in order to: recognize distinguished contributions to control systems science or engineering.

In 1957 he was elected member to the National Academy of Sciences, the oldest and most prestigious U.S. National Academy established at the height of the Civil War, in 1863, by then President Abraham Lincoln.

Being a deep thinker as well as a lucid writer he significantly contributed to three important COSPUP studies: Basic Research and National Goals (1965), Applied Science and Technological Progress (1967) and Technology: Processes of Assessment and Choice (1969). These studies had the additional distinction of being the first ever to be prepared by the Academy for the Legislative Branch, or more specifically for the Committee on Science and Astronautics of the U.S. House of Representatives, thus fulfilling the Academy's mandate, under its Charter, as an advisory body to the U.S. Government.

It is a historical irony that Hendrik Wade Bode, the man who helped develop the robot weapons that brought down the Nazi V-1 flying bombs over London during WWII, was actually serving in the same committee and sitting at the same table as Wernher von Braun who worked on the development of the V-1 and was the head of the team which developed the V-2, the weapon that terrorised London.

He is among the founding members and served as a regular Members and associates of the United States National Academy of Engineering of the National Academy of Engineering, that was created on December 1964, only the second U.S. National Academy in one hundred and one years since the inception of the first, and which now forms part of the United States National Academies.

He thus helped sublimate the age old debate of engineers versus scientists and elevated it into a debate between academics. This subtle, yet powerfully symbolic accomplishment, constitutes a compelling part of his legacy.

Hendrik Wade Bode died at the age of 76, at his home in Cambridge, Massachusetts

- Network Analysis and Feedback Amplifier Design (1945)
- Synergy: Technical Integration and Technological Innovation in the Bell System (1971)
- Counting house (Fiction) Hendrik W. (Hendrik Wade) Bode and Barbara Bode Harper's magazine The Lion's mouth dept. pp. 326-329, August 1936

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Last updated on Saturday August 23, 2008 at 02:30:13 PDT (GMT -0700)

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Last updated on Saturday August 23, 2008 at 02:30:13 PDT (GMT -0700)

View this article at Wikipedia.org - Edit this article at Wikipedia.org - Donate to the Wikimedia Foundation

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