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Control Moment Gyroscope (CMG) is an effective candidate for agile satellites and large spacecraft attitude control because of its powerful torque amplification capability. The most serious situation, however, in using CMG is the inherent geometric singularity problem, where there’s no torque output along a particular direction. Space expansion method has been proposed in this work for the singularity analysis. Based on inverse mapping transformation, an expanded Jacobian matrix which is a full rank square matrix is obtained. The singular angle sets of the 3-parallel cluster and pyramid cluster are distinguished using space expansion method. An effective hybrid steering strategy, able to deal with the elliptic singularity, is further proposed. Simulation results demonstrate the excellent performance of the proposed steering logic compared to the generalized singular robust logic and pseudo inverse logic in terms of energy consumption and torque error. 相似文献
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对数正态分布场合环境因子基于截尾样本的统计分析 总被引:1,自引:0,他引:1
本文导出了寿命分布为对数正态分布时基于截尾样本环境因子的点估计和近拟置信限,对所给近似置信区间作了模拟研究。 相似文献
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以结构系统的可靠度作为薄壁梁系结构的优化控制参数。用改进的分枝眼界法判从主要失效模式。用PNET法计算结构系统的可靠度。导出了两种梁系结构可靠度的灵敏度分析表达式。提出最佳矢量型算法的选代公式,有效地求解了Ⅰ型截面梁系结构在系统可靠度约束下的最小重量设计问题;且在其中通过设计变量连接来满足薄壁梁的稳定性要求。算例的结果说明了方法的有效性。 相似文献
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Investigation of the infrared characteristics of a rocket nozzle is very important for the study of infrared initiating technology. The Narrow-Band Zone model is developed for that purpose. The spectral transmission and absorption factors are introduced, and the equations between radiative heat flux and the temperature of waill surfaces and gas are developed. The radiative heat transfer in one axisymmetric cylindrical enclosure filled with homogeneous radiative participating medium is computed with the Narrow-Band Zone model and compared with those in the reference documents. The comparison shows good agreement. The radiative heat transfer to the nozzle of one rocket engine is also calculated with the Narrow-Band Zone model, and the outgoing radiative energy flux and energy rate integrated in a mid-wave infrared band 2-6 pm, a long-wave infrared band 8-14 pm and the full wave band are analyzed. The following conclusions can be derived: the spectral radiation from the inlet and outlet of the nozzle show apparent spectral discontinuity, which appears greater in the 2.7-2.95 pm than in the neighboring wave band. The spectral outgoing radiative energy flux of nozzle wail is similar to that of gray body, which decreases with wavelength in 2-14 pm. The outgoing radiative energy flux on the nozzle wall is greater in the cylindrical and contracting section of nozzle, but smaller in the divergent section, which is determined by temperature. The nozzle of the rocket engine radiates most energy in the mid-wave surfaces by absorption. The most important feature of gas radiation is the strong selection of the waveband, so the detailed study of the infrared characteristics of nozzle of the rocket engine should be carried out on narrow-band computation. 相似文献
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