空间目标姿态角估计与RCS反射图生成

介绍了一种空间目标姿态角估计方法,并在此基础上生成了RCS反射图.该方法主要是在直角坐标系中对目标的运动特征用二次项进行描述,并用最小二乘估计求解二次方程,从而根据运动方程估计出目标的姿态角.实测数据验证结果表明,该方法能够有效地估计出空间目标的姿态角变化情况,并可反映出目标RCS随其姿态变化的规律.     

火星载人探测中辐射防护综述

火星探测是人类太空探索的重要组成部分,火星载人探测中航天员的辐射安全问题是人们最为关心的问题。文章扼要介绍了美国/俄罗斯火星载人探测技术的发展过程,重点阐述了探测中的辐射环境、辐射效应以及国外探测结果;在此基础上,对火星探测中的辐射剂量进行了预示,提出了辐射防护建议。     

关于宇航标准体系建设的几点思考

在论述宇航标准顶层设计目的与需求的基础上,分析我国建立宇航标准所处的技术环境特点以及需要重点考虑的问题,并提出建立我国宇航标准体系的原则及途径的建议.     

卫星表面放电效应模拟器研制

文章介绍了自行研制的卫星表面放电效应模拟器。根据模拟器基本原理和应实现的主要功能,提出了模拟器的技术指标和具体设计方案;研制了模拟器标定系统,并利用该标定系统对模拟器放电电压和放电电流脉冲特性进行了测试标定。结果表明所研制模拟器的放电特性符合卫星表面放电效应模拟试验的要求,可以用于表面放电效应评估。     

三维针刺C/C-SiC复合材料的烧蚀性能

采用"化学气相渗透+先驱体浸渍裂解"(CVI+PIP)混合工艺,制备了三维针刺C/C-SiC复合材料,使用氧气流量和乙炔流量之比为2∶1的氧乙炔焰,研究了复合材料的烧蚀性能,烧蚀时间长达600 s;分别用扫描电镜和表面能谱,分析了烧蚀表面的形貌和成分。结果表明,复合材料的线烧蚀率和质量烧蚀率的平均值分别是0.004 3 mm/s和0.001 4 g/s。烧蚀表面不同区域微观形貌和烧蚀机理不同,烧蚀中心以基体氧化流失、C纤维的氧化以及气流冲刷为主;在过渡区域,烧蚀是以SiC基体的氧化和气流冲刷为主;烧蚀边缘则以SiC基体的热氧化为主。C/C-SiC复合材料在氧-乙炔条件下的烧蚀机制是热化学烧蚀、热物理烧蚀和机械冲刷的综合作用。     

外形及工况参数对轴承柔性保持架动力学性能的影响

考虑保持架柔性处理及滚动轴承各组件间的相互作用关系,利用ADAMS/View平台构建了真空条件下不同保持架的轴承刚柔耦合多体动力学分析模型,采用正交试验法分析了转速、保持架厚度和兜孔形状对保持架动态特性的影响规律。结果表明：随着轴承转速增加,保持架转速稳定性降低,动态接触力和打滑率升高,质心轨迹呈“筒状”;保持架厚度对保持架动态性能影响最大,质心轨迹受兜孔形状影响最大;动量轮用保持架最优工况及设计为：轴承转速为2000 (r/min),厚度为2 mm,兜孔形状为方型兜孔。     

基于几何特征的飞行器RCS高效计算方法(英文)

Taking into account the influences of scatterer geometrical shapes on induced currents, an algorithm, termed the sparse-matrix method （SMM）, is proposed to calculate radar cross section （RCS） of aircraft configuration. Based on the geometrical characteristics and the method of moment （MOM）, the SMM points out that the strong current coupling zone could be predefined according to the shape of scatterers. Two geometrical parameters, the surface curvature and the electrical space between the field position and source position, are deducted to distinguish the dominant current coupling. Then the strong current coupling is computed to construct an impedance matrix having sparse nature, which is solved to compute RCS. The efficiency and feasibility of the SMM are demonstrated by computing electromagnetic scattering of some kinds of shapes such as a cone-sphere with a gap, a bi-arc column and a stealth aircraft configuration. The numerical results show that： （1） the accuracy of SMM is satisfied, as compared with MOM, and the computational time it spends is only about 8% of the MOM; （2） with the electrical space considered, making another allowance for the surface curvature can reduce the computation time by 9.5%.     

Evaluation of active hybrid fuel cell/battery power sources

Hybrid fuel cell/battery power sources have potentially widespread uses in applications wherein the power demand is impulsive rather than constant. Interposing a dc/dc converter between a fuel cell and a battery can create two configurations of actively controlled hybrid fuel cell/battery power sources. Those two configurations are compared using both theory and experiment with special attention to the peak power enhancement, and power losses in the converter. Both of the defined configurations were built, using a 35 W polymer electrolyte membrane (PEM) fuel cell, an 8-cell lithium-ion battery pack, and a high-efficiency power converter. Both two configurations yielded a peak power output of 135 W, about 4 times as high as the fuel cell alone could supply, with only a slight (13%) increase of weight. The converter losses were quantitatively analyzed. Which of the two configurations yields a smaller loss depends on the load power demand characteristics including peak power and load duty ratio. The study results provide guidance for the design of hybrid sources according to the particular load power requirements.     

全色图像像质与军事效用

遥感图像的军事效用即图像判读解译能力取决于像质,是像元分辨率、图像调制传递函数值(MTF)、信噪比等的函数,与设计参数的选取,制造的精度,运行的状态,图像处理水平密切相关.     

单通道SAR实现ATI动目标检测的新方法

研究了采用单通道合成孔径雷达(SAR,Synthetic Aperture Radar)多视沿航迹向干涉(ATI,Along Track Interferometry)实现地面慢速运动目标指示的检测方法.分析了该方法所需的步骤,即利用重叠或不重叠的窗构造子视,对子视分别成像,相位误差校正并求干涉.关于其中起关键作用的相位误差校正步骤,提出了利用信号子空间投影进行相位配准的补偿方法.借助该鲁棒的自适应方法可以从某种程度上解决子图像间的去相关问题,降低相位随机性的影响,从2幅子视图像的干涉相位图上敏锐地检测到运动目标.通过仿真实验,验证了该方法可以有效地从强杂波中检测动目标,为单通道SAR实现地面运动目标指示(GMTI,Ground Moving Target Indication)、扩展已有SAR系统功能提供可靠的途径.