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  • Other Sources  (3)
  • 1980-1984  (3)
  • 1930-1934
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  • 1
    Publication Date: 2019-06-28
    Description: Additional insight is provided into the use of the Doyle-Stein (1979, 1981) technique in aeroelastic control problems by examining the application of the method to a flutter control problem. The system to be controlled consists of a full-size wind tunnel model of a wing, plus an aileron, an actuator, and an accelerometer used to sense the motion of the wing. A full-state feedback controller was designed using linear optimal control theory, and a Kalman filter was used in the feedback loop for state estimation. The filter design procedure is explained along with that to improve closed-loop properties of the system. The locus of the poles of the filter is examined as a scalar design parameter is varied. The Doyle-Stein design procedure is shown to substantially improve the stability properties of an active flutter controller designed using the linear quadratic Gaussian control theory.
    Keywords: AIRCRAFT STABILITY AND CONTROL
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  • 2
    Publication Date: 2019-07-13
    Description: Ferromagnetic resonance intensity, I(s), relies on the absence or presence of single-domain Fe formed during impact melting by autoreduction of Fe(2+) in the melt to distinguish volcanic from impact glass spherules in the lunar soil. SEM inspection of individual glass bead surfaces gave reliable evidence of the mode of glass genesis. Ferromagnetic resonance intensity was tested against the Apollo 15 and 17 volcanics. I(s) values of less than one were found in 94% of the volcanic glasses, implying the absence of single-domain Fe, while 75% of the impact glasses had elevated I(s) values. These samples lack single-domain Fe, and may represent impact melts of bedrock with little or no regolith contribution. Both the primary discrimination of volcanic and impact glasses, and the secondary one of bedrock-derived impact melts from impact melts partially or entirely derived from regolith, have been demonstrated for the I(s) technique.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Science Conference; Mar 15, 1982 - Mar 19, 1982; Houston, TX
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  • 3
    Publication Date: 2019-07-13
    Description: This paper describes the application of Linear Quadratic Gaussian (LQG) methodology to the design of active control systems for suppression of aerodynamic flutter. A full-size wind tunnel model of a supercritical wing with associated sensors and actuators comprises the system to be controlled. Results of a synthesis methodology that provide small values of rms response, insensitivity to flight condition, and robust stability are presented. Results of control surface and sensor position optimization are also presented. Both frequency response matching and residualization are used to obtain practical flutter controllers.
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA PAPER 80-1758 , Guidance and Control Conference; Aug 11, 1980 - Aug 13, 1980; Danvers, MA
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