187,381 research outputs found

    Fault Diagnosis for Satellite Sensors and Actuators using Nonlinear Geometric Approach and Adaptive Observers

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    This paper presents a novel scheme for diagnosis of faults affecting sensors that measure the satellite attitude, body angular velocity, flywheel spin rates, and defects in control torques from reaction wheel motors. The proposed methodology uses adaptive observers to provide fault estimates that aid detection, isolation and estimation of possible actuator and sensor faults. The adaptive observers do not need a-priori information about fault internal models. A nonlinear geometric approach is used to avoid that aerodynamic disturbance torques have unwanted influence on the fault estimates. An augmented high fidelity spacecraft model is exploited during design and validation to replicate faults. This simulation model includes disturbance torques as experienced in low Earth orbits. The paper includes an analysis to assess robustness properties of the method with respect to parameter uncertainties and disturbances. The results document the efficacy of the suggested methodology

    De gehalten aan stikstof, fosfor en kalium in blanke vleeskalveren

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    Door ECLNV is gevraagd om de hoeveelheden en gehalten aan N, P en K in blanke vleeskalveren, die onder praktijkomstandigheden worden gevoerd en gehouden gedurende de opfok en op het eindgewicht vast te stellen.Voor dit doel zijn in totaal 22 blanke vleeskalveren afkomstig uit een proef van Van der Togt en Gerrits (1998) nader chemisch onderzocht. In dit rapport zijn de resultaten van deze studie weergegeven

    De gehalten aan stikstof, fosfor en kalium in blanke vleeskalveren

    No full text
    Door ECLNV is gevraagd om de hoeveelheden en gehalten aan N, P en K in blanke vleeskalveren, die onder praktijkomstandigheden worden gevoerd en gehouden gedurende de opfok en op het eindgewicht vast te stellen.Voor dit doel zijn in totaal 22 blanke vleeskalveren afkomstig uit een proef van Van der Togt en Gerrits (1998) nader chemisch onderzocht. In dit rapport zijn de resultaten van deze studie weergegeven

    Adaptive FTC based on Control Allocation and Fault Accommodation for Satellite Reaction Wheels

    No full text
    This paper proposes an active fault tolerant control scheme to cope with faults or failures affecting the flywheel spin rate sensors or satellite reaction wheel motors. The active fault tolerant control system consists of a fault detection and diagnosis module along with a control allocationand fault accommodation module directly exploiting the on-line fault estimates. The use of the nonlinear geometric approach and radial basis function neural networks allows to obtain a precise fault isolation, independently from the knowledge of aerodynamic disturbance parameters, and to design generalised estimation filters, which do not need a priori information about the internal model of the signal to be estimated. Theadaptive control allocation and sensor fault accommodation can handle both temporal faults and failures. Simulation results illustrate the convincing fault correction and attitude control performances of the proposed system

    Fault diagnosis for satellite sensors and actuators using nonlinear geometric approach and adaptive observers

    No full text
    This paper presents a novel scheme for diagnosis of faults affecting sensors that measure the satellite attitude, body angular velocity, flywheel spin rates, and defects in control torques from reaction wheel motors. The proposed methodology uses adaptive observers to provide fault estimates that aid detection, isolation, and estimation of possible actuator and sensor faults. The adaptive observers do not need a priori information about fault internal models. A nonlinear geometric approach is used to avoid that aerodynamic disturbance torques have unwanted influence on the fault estimates. An augmented high-fidelity spacecraft model is exploited during design and validation to replicate faults. This simulation model includes disturbance torques as experienced in low Earth orbits. This paper includes an analysis to assess robustness properties of the method with respect to parameter uncertainties and disturbances. The results document the efficacy of the suggested methodology

    Fritz Blanke, Aus der Welt der Reformation, 1960

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    Wendel François. Fritz Blanke, Aus der Welt der Reformation, 1960. In: Revue d'histoire et de philosophie religieuses, 40e année n°4,1960. p. 418

    F. Blanke, J. G. Hamann als Theologe, Tubingue, Mohr, 1928

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    Marty Jacques. F. Blanke, J. G. Hamann als Theologe, Tubingue, Mohr, 1928. In: Revue d'histoire et de philosophie religieuses, 8e année n°5, Septembre-octobre 1928. p. 483
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