Materials selection for electronic enclosures in space environment considering electromagnetic interference effect

Using low power electronic devices for space applications to reduce the mass and energy consumption has lead to electromagnetic interference (EMI) problem. Electronic enclosures are used to shield electronic devices against EMI. In the past, electromagnetic shielding has been mainly the only criteria considered in electronic enclosure design. However, there are several structural and thermal requirements for selection of shielding materials which should also be taken into account. In this research work, three quantitative materials selection methods, i.e. Digital Logic (DL), Modified Digital Logic (MDL), and Z-transformation, are employed to select the best material from among a list of candidate materials. Composite and metallic electronic enclosures are explored and the best material is selected. Z-transformation method is applicable to both of the considered case studies while DL and MDL can only be used for solving one of them. Z-transformation method ranks aluminum as the first choice among various metallic materials. The wide range of Z-transformation application and its practical results confirm the superiority of Z-transformation method over DL and MDL methods.     

Optimal network topology of relative navigation and communication for navigation sharing in fractionated spacecraft cluster

Navigation sharing as a key technology provides orbit and attitude information broadcasting for the whole fractionated spacecraft cluster (FSC). The navigation sharing concept has already been proposed for some years. However, the problem of achieving the optimal navigation sharing by designing the proper network topology is still unsolved, especially in the case that some members of the cluster have absolute navigation devices, some just have relative navigation devices and some only have communication devices. In this paper, a comprehensive model of describing the navigation sharing problem in FSC is proposed. The model of network topology constructing by relative navigation links and communication links is established. By using the graph theory and genetic algorithm as the tool, the conditions for navigation sharing in FSC with different sharing degrees are obtained. Finally, some examples are presented to test the methods, and it has been found that, the absolute positions and attitudes of all the members can still be determined even some members in FSC have no absolute navigation devices.     

航天器总装过程特种车辆运输问题的研究

文章针对航天器总装过程所涉及的特种车辆转运问题进行研究。通过对特种车辆种类和航天器各平台总装涉及特种车辆数量分析,提出集装箱运输方案并对集装箱进行设计、实施,取得了良好效果,同时指出集装箱化运输也是航天器工装运输的趋势。     

Solar wind turbulence during the solar cycle deduced from Galileo coronal radio-sounding experiments

Seven coronal radio-sounding campaigns were carried out during the active lifetime of the Galileo spacecraft in the years 1994–2002. The observational data analyzed in the present work are S-band frequency fluctuation measurements recorded during the solar conjunctions at different phases of solar activity cycle #23, specifically: periods near solar maximum (three conjunctions), near solar minimum (three conjunctions) and during the ascending phase (one conjunction). These data are all applicable to low heliographic latitudes, i.e. to the slow solar wind. The rms frequency fluctuation and power-law index of the frequency fluctuation temporal spectra are determined as a function of heliocentric distance. The turbulence power spectrum tends to be flatter inside ca. 20 solar radii during all phases of the solar cycle. This coincides with a transition in the flow from the inner acceleration region to the outer region of constant velocity. The radial falloff rate and absolute level of the rms frequency fluctuation are essentially invariant over the solar cycle.     

基于正弦基础激励的航天器结构模型修正方法

正弦振动试验是航天器系统级和单机产品需要开展的常规试验,充分利用工程中积累的正弦试验数据进行结构模型修正具有重要的工程意义。文章首先介绍了基础激励下结构模型修正方法,通过矩阵分块、待修正参数归一化、参与修正的频率点选择等步骤,推导出基于基础激励的模型修正公式;然后对国际通用算例GARTEUR桁架结构的有限元模型进行修正,分析修正后模型在修正频段内和修正频段外计算所得模态频率,验证修正后模型对模态频率的复现和预示能力,通过对比试验模型、分析模型和修正后模型中4个典型节点的响应曲线,检验修正后模型精度。结果表明:修正后模型的模态频率和响应曲线均与试验模型趋于一致,证实了该修正方法对GARTEUR结构修正的有效性。     

空间热物理技术发展的探讨

文章以航天器和火箭发动机中的工程热物理问题为背景,探讨了航天器热控技术的现状和发展趋势,介绍了火箭发动机热设计、推进剂燃烧等问题的发展方向.     

航天器研制全过程污染控制工程

污染控制体系的完善,控制技术的成熟,对航天器研制至关重要,本文简要说明了污染控制的重要性,以及由于污染造成航天器失效的例子,比较详细地介绍了航天器项目各阶段污染控制的一些方法,最后简要介绍了污染领域的发展方向和急需解决的问题.     

国外航天运输系统防热系统,结构和材料的总体分析研究

对近年来国外航天运输系统包括飞船、航天飞机和空天飞机等的防热方案的选用方向、防热结构和防热材料的研究与应用以及发展方向进行了高度概括与分析，采用了新的分类方法，介绍了各种新型的防热系统、结构和材料。     

航天器材料空间环境适应性评价与认定准则研究

航天器材料空间环境适应性是指航天器材料适应空间环境的能力,同时又是航天器系统级空间环境适应性的基础。确保航天器材料空间环境适应性是航天器研制初期重要环节。文章首先介绍了航天器材料的空间环境适应性类型;其次列举了材料空间环境适应性评价试验标准体系;然后分析了空间环境适应性评价手段与认定准则,包括选材阶段的评价试验、采购和使用阶段的验收试验以及空间环境适应性的认定。文章对我国航天器材料空间环境适应性评价与认定工作提出若干建议,为航天器材料选择和空间环境适应性控制提供参考。     

载人航天器密封舱内强制通风下的火灾温度场及流场特性仿真分析

文章建立微重力环境下载人航天器密封舱简化物理模型,利用FDS软件仿真分析火源在密封舱中心位置时不同送风角度（θ=0°、θ=45°、θ=60°）下舱内温度和烟气浓度的分布规律。分析结果显示：需要在大功率设备上方两侧布置火灾探测器;不同送风角度下的速度场不同,造成舱内温度分布规律也不同;当送风角度θ=45°、θ=60°时,密封舱内的烟气与θ=0°时相比更易排出。分析结果可为载人航天器密封舱内送风口及火灾探测器的设置提供参考。