Browsing by Author "CHEN, YM"

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HIGH-PERFORMANCE PIRANI VACUUM GAUGE
(1995-11-01)
SHIE, JS
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CHOU, BCS
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CHEN, YM
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交大名義發表
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光電工程學系
As an extension of previous work in our laboratory, a wide-range Pirani gauge that is capable of measuring vacuum pressure down to 10(-7) Torr reproducibly has been built, The micromachined Pirani sensor used in the experiments has a suspended membrane that is supported by the nearly radiation-limited, thermally insulating beam leads crossing over a V-groove cavity. A method of partial dummy compensation, as proposed previously by Weng and Shie for eliminating the ambient drift, is proved here to be very effective with a thermal drift as small as only 5.7 mu V/degrees C. It has also been found that a thermal-stress-induced piezoresistive effect, which has a profound influence on the limitation of measurement, appears in the constant-bias operation wherein the sensor temperature rises with the reduction of gas pressure and therefore thermal conduction. This effect causes the irreproducibility of pressure measurements by the device below 10(-5) Torr. In addition to its inherently higher sensitivity, a constant-temperature circuit together with a thermoelectric stabilization of the sensor substrate temperature can eliminate the induced piezoresistive error. The constant-temperature circuit operating on the micro-Pirani sensor together with the above-mentioned temperature compensation and the stabilization methods have extended gauge capability down to 10(-7) Torr, which is only limited by the signal readout resolution (similar to 1 mu V). This is three orders of magnitude more sensitive than the conventional vacuum gauges of the thermal conductivity type. (C) 1995 American Vacuum Society
MODIFIED RECURSIVE LEAST-SQUARES ALGORITHM FOR PARAMETER-IDENTIFICATION
(1992-02-01)
CHEN, YM
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WU, YC
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電控工程研究所
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Institute of Electrical and Control Engineering
A modified recursive least-squares algorithm is proposed for estimating the parameters of a linear system, including ill-conditioned situations. The proposed algorithm is obtained by minimizing the modified cost function in which the initial guess in the cost function of an ordinary recursive least-squares (RLS) algorithm is replaced by the latest estimate. Analysis of the convergence shows that the proposed algorithm has a better convergence rate than the ordinary RLS algorithm. The extension of the algorithm to the time-varying case has also been considered.
MULTI-MICROPROCESSOR-BASED CARTESIAN-SPACE CONTROL TECHNIQUES FOR A MECHANICAL MANIPULATOR
(1986-06-01)
LIU, CH
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CHEN, YM
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電控工程研究所
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Institute of Electrical and Control Engineering
PLASTIC ZONES AND CHARACTERISTICS-LINE FAMILIES FOR OPENINGS IN ELASTOPLASTIC ROCK MASS
(1990-10-01)
PAN, YW
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CHEN, YM
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交大名義發表
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National Chiao Tung University
QUASI-STATIC ELECTRIC-FIELD-ENHANCED DIFFRACTION EFFECTS IN A NEMATIC LIQUID-CRYSTAL FILM
(1985)
CHEN, SH
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PAN, CL
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CHEN, YM
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LIAO, HH
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交大名義發表