挠性悬臂板的变结构控制研究

针对航天器上太阳帆板这种悬臂外伸薄板结构的挠性附件 ,在存在建模参数不确定及外部扰动条件下所引起的振动 ,本文采用压电致动片作为执行器 ,将变结构控制应用于板的主动振动控制。通过仿真研究结果与应变律反馈控制比较 ,可知变结构控制具有较强的鲁棒性 ,同时控制器结构简单 ,易于实现     

品牌延伸的风险与防范

摘 要 品牌延伸是指尽量利用已成功的品牌来推出改进型产品或者新产品。随着品牌在市场上的成功，企业的品牌资源意识也逐渐增强，他们希望成功的品牌带来更大的收益。经品牌延伸后，不同的产品彼此共享同样的品牌名称及其品牌意义。新产品的加入不可避免地对原有的品牌意义产生影响。这种影响可能是正面的，即加强原有品牌的识别力；也可能是负面的，即削弱了原有的品牌识别力。因此，品牌延伸不是任意的，品牌的识别意义界定了延伸的方向和最终过程。这个问题成为研究品牌延伸原理和决策的基本出发点。     

自适应变结构控制的切换函数研究

根据自适应变结构控制的基本思想 ,推导了滑模到达条件 ,并提出了切换线斜率的三种变化规律 :线性规律、幂次规律和指数规律 ,设计了相应形式的切换函数。最后 ,通过仿真实例对各种切换函数进行研究 ,仿真结果说明 :采用二次幂规律控制效果最佳。     

基于视线制导的交会停靠控制方法

空间交会停靠段的控制经常采用的一种方法是基于视线位置信息的平行接近法。本文对纵向控制中的非线性滑动模态控制方法进行了研究和改进 ,考虑了视线角对纵向控制的耦合作用 ,增加了耦合项 ,并进行了存在性和稳定性分析。对于横向和纵向同时协调控制 ,提出一种多变量互相耦合的非线性滑动模态视线制导控制方法 ,并对同时协调控制进行了存在性和稳定性分析     

卫星GPS组合姿态确定系统方案研究

采用ＧＰＳ定姿技术作为卫星高精度自主姿态确定系统的备份，可以提高系统可靠性。在小型和微小卫星上采用ＧＰＳ定姿技术，保证在满足重量、功耗和其它技术指标的条件下，姿态和轨道控制系统全面满足任务要求。本方案为探索当今姿态和轨道控制系统基本型的研究迈出了一步。     

Numerical study on similarity of plume infrared radiation between reduced-scale solid rocket motors

This study seeks to determine the similarities in plume radiation between reduced and full-scale solid rocket models in ground test conditions through investigation of flow and radiation for a series of scale ratios ranging from 0.1 to 1. The radiative transfer equation(RTE) considering gas and particle radiation in a non-uniform plume has been adopted and solved by the finite volume method(FVM) to compute the three dimensional, spectral and directional radiation of a plume in the infrared waveband 2–6 μm. Conditions at wavelengths 2.7 μm and 4.3 μm are discussed in detail, and ratios of plume radiation for reduced-scale through full-scale models are examined. This work shows that, with increasing scale ratio of a computed rocket motor, area of the hightemperature core increases as a 2 power function of the scale ratio, and the radiation intensity of the plume increases with 2–2.5 power of the scale ratio. The infrared radiation of plume gases shows a strong spectral dependency, while that of Al_2O_3 particles shows spectral continuity of gray media.Spectral radiation intensity of a computed solid rocket plume's high temperature core increases significantly in peak radiation spectra of plume gases CO and CO_2. Al_2O_3 particles are the major radiation component in a rocket plume. There is good similarity between contours of plume spectral radiance from different scale models of computed rockets, and there are two peak spectra of radiation intensity at wavebands 2.7–3.0 μm and 4.2–4.6 μm. Directed radiation intensity of the entire plume volume will rise with increasing elevation angle.