Harold Locke Hazen (August 1, 1901 – February 21, 1980) was an American electrical engineer. He contributed to the theory of servomechanisms and feedback control systems. In 1924 under the lead of Vannevar Bush, Hazen and his fellow undergraduate Hugh H. Spencer built a prototype AC network analyzer, a special-purpose analog computer for solving problems in interconnected AC power systems. Hazen also worked with Bush over twenty years on such projects as the mechanical differential analyzer
Hazen was born at Philo, Illinois in 1901 and attended high school at Three Rivers, Michigan. He went to Massachusetts Institute of Technology (MIT) as an undergraduate student in 1920. When he graduated from MIT in 1924, he briefly worked for General Electric. In 1925 he returned to MIT as research assistant and instructor in 1926. he obtained his Master’s degree in 1929 and his doctorate in 1931. In 1934 Hazen published two papers on the theory and design of servomechanisms which provided clear descriptions of the operation of servos and a design methodology.
Gordon Stanley Brown (August 30, 1907 in Australia – August 23, 1996 in Tucson, Arizona) was a professor of electrical engineering at MIT. He originated many of the concepts behind automatic-feedback control systems and the numerical control of machine tools.From 1959 to 1968, he served as the dean of MIT’s engineering school. With his former student Donald P. Campbell, he wrote Principles of Servomechanisms in 1948, which is still a standard reference in the field.
