This research was funded by the National Science Foundation under grant number DDM-9115417 from April 1992 to September 1995. The Principal Investigators were Dr. Murray Black and Dr. Guy Beale of the Electrical and Computer Engineering Department. Significant contributions to the research were provided by Research Associate Professor Dr. Yong Lai Tian; Graduate Research Assistants Francisco Arteaga-Bravo and Mengli Li; and by our industrial collaborators, Dr. Richard Silberglitt and Dr. Iftikhar Ahmad.
The purpose of this research was to develop an automatic control system to prevent thermal runaway from occurring when low-loss ceramics, such as alumina or mullite, are heated by microwave energy. The result was a computer-based control system which uses measurements of temperature and reflected microwave power to control the value of the applied microwave power, the position of a mechanical plunger, and the size of an inductive iris. The iris and plunger were adjusted to minimize the amount of reflected power, and the applied power level was controlled to regulate the temperature of the specimen at the correct value.
The design of the temperature control system was based on an analytic model of the heating process. The movements of the plunger and iris are controlled by a search process based on expert knowledge. Actual heating experiments with silicon carbide rods and with mullite tubes have verified the ability of the control system to prevent thermal runaway and the robustness of the control system to wide variation in material properties.
Figures with brief descriptions of specific results of this research.
Publications related to this research.
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