共查询到20条相似文献,搜索用时 31 毫秒
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为了研究真空环境设备内溅射靶温度升高后对30 cm离子推力器的热辐射影响,采用有限元分析的方法,首先对真空舱内的离子推力器羽流分布进行了模拟,在获得羽流对溅射靶造成的温度变化后,进一步分析了溅射靶温度升高对离子推力器温度以及栅极热形变位移所造成的影响.仿真结果显示,推力器羽流可采用定向分子流模型进行描述,羽流在真空舱内... 相似文献
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《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1999,23(1):137-147
Meteor storms are of concern to satellite operators because they are a natural impact hazard. Little is known about their cause and effect. Meteor storms are rare and have never been studied by modern techniques. Now, the upcoming Leonid returns of November '98 and '99 offer a once-in-a-lifetime opportunity to gather data that can help assess the impact hazard of meteor storms and provide a wealth of data on the physics and chemistry of meteoroids accreting into the Earth's atmosphere. Three months before the Nov. '98 return, we here give an update of what to expect and what observing efforts are going to be made. 相似文献
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空间天气对地球及近地空间具有重要影响,大的空间天气事件对中上层大气动力学和成分具有不同的影响。利用全大气耦合模式WACCM,针对太阳耀斑、太阳质子、地磁暴三类事件,以太阳活动平静期2015年5月10-14日的GEOS-5数据为模式背景场,通过F10.7、离子产生率、Kp及Ap指数设置,分别模拟三类事件对临近空间大气温度、密度和臭氧的影响。结果表明耀斑事件在三类事件中对临近空间大气温度和密度的影响最为显著。平流层大气温度增加是由耀斑辐射增强引起平流层臭氧吸收紫外辐射发生的光化学反应所致,耀斑事件引起平流层和低热层温度增加约为2~3 K,低热层大气相对密度增加在6%以内;太阳质子事件及磁暴事件主要影响低热层,但太阳质子事件和磁暴事件对低热层温度扰动不大于1 K。 相似文献
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基于摄动轨道的卫星自主天文导航仿真研究 总被引:5,自引:0,他引:5
针对星光折射间接敏感地平的卫星自主天文导航方法 ,利用推广的卡尔曼滤波方法进行仿真研究。为了准确建立运动模型 ,在系统方程中引入了非球形地球引力中的二阶带谐项 ;在考虑具有指数密度的球状分层大气的基础上 ,建立了以星光视高度为观测量的量测方程。在建立了推广的卡尔曼滤波方程后 ,文章进行了计算机仿真 ,并对仿真结果进行了详细的误差分析 ,结果表明基于摄动轨道的星光折射间接敏感地平的卫星自主天文导航方法能取得较高的导航精度 相似文献
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《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1986,6(3):177-186
Two traditional theoretical interpretations of the observed plasmapause are compared, namely, the plasmapause as: 1. The boundary between closed flux tubes that have been in the inner magnetosphere for several days and those that have recently drifted in from the magnetotail or 2. the last closed electric equipotential. Although the two interpretations become equivalent in the case where the electric-field pattern is steady for several days, interpretation 1 seems theoretically more secure for typical magnetospheric conditions, due to the essentially time-dependent nature of the mangetospheric electric field. The results of old theoretical studies of the effects of time variations in the electric-field pattern on the shape of the plasmapause are reviewed briefly. The formulation of the present version of the Rice Convection Model is also reviewed. Preliminary results of recent computations of quiet-time electric fields, carried out with this model, are presented and discussed. Quiet-time thermospheric winds are found to have only minor effects on drift paths of magnetospheric particles. 相似文献
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基于混杂系统的空间飞行器悬停控制 总被引:2,自引:1,他引:2
基于空间飞行器的轨道动力学原理,利用混杂系统模型研究了悬停轨道问题,建立了悬停轨道的混杂系统模型;借此模型,针对目标星轨道为椭圆的情况,提出了等距离悬停轨道控制和椭圆悬停轨道控制两种方案,分别推导出在这两种方案下对悬停星所施加的控制力。数值仿真结果表明,分别对悬停星施加相应的控制力,能够实现对目标星的悬停。 相似文献
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E. Illés A. Horváth 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(8):49-52
L-grooves are the consequence of layered structure of Phobos, which are made up of parallel layers of different composition or hardness. 相似文献
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基于Web技术的产品数据管理研究 总被引:15,自引:0,他引:15
将Web技术引入产品数据管理系统(PDM)的研究和设计,分析了PDM系统中原有构架的特点与存在的不足,利用Web技术所提供独到的网络、数据库和分布式处理技术,结合开发实例提出了在Internet/Intranet解决方案下开发和研究产品数据管理系统的基本构想,并给出产品数据管理应用的组织和底层数据模式,研究了其对产品数据管理技术应用前景的影响.研究表明,Web技术的引入,将有力地推进产品数据管理技术的发展和应用. 相似文献
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基于RDSS辅助的Doppler/SINS组合导航系统研究 总被引:1,自引:0,他引:1
Doppler/SINS组合导航系统具有输出水平速度误差较小、平台角误差较小的优点 ,但存在经纬度误差较大的缺点 ,故不能作为独立的导航定位系统 ;而双星定位系统(RDSS)可输出较高精度的经纬度信息 ,但存在定位滞后的缺陷。利用Doppler/SINS的输出水平速度可以补偿RDSS的位置滞后 ,同时经过位置补偿后的RDSS系统可实时修正Doppler/SINS组合导航系统。仿真结果表明 ,基于RDSS辅助的Doppler/SINS组合导航系统能有效地克服Doppler/SINS系统的缺点 ,是一种新型的组合导航系统 ,可应用于导航定位精度要求较高的场合 相似文献
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P. Muralikrishna V.H. Kulkarni 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
Dust particles of meteoric origin in the lower E-region can affect the conductivity parameters by varying the effective collision frequency and by causing electron bite outs through the capture of ambient electrons. In magnetized plasma, neutral dust particles can alter the effective collision frequency parameters and thus affect the Pedersen and Hall conductivities in the electrojet region. The Cowling conductivity profile is determined by the height profiles of the Hall and Pedersen conductivities. The collision parameters altered by the neutral dust particles can be considerably different from those estimated from atmospheric models, in the lower E-region heights where dust particles of meteoric origin are known to exist in large numbers. A significant fraction of these dust particles may capture free electrons from the ambient medium and get charged negatively. This can result in reduction in the number density of free electrons especially below the electrojet peak where the dust particles can be present in large numbers, at least on days of large meteor showers. This, in turn, can once again alter the vertical profile of the east–west Hall current driven by the vertical Hall polarization field and under favorable conditions, can even account for the reversal of the electrojet currents below the current peak. Assuming a realistic model for the distribution of neutral dust particles, the conductivity parameters are estimated here. Conditions under which the dust particles can cause partial reversals in the electrojet currents are critically examined here. 相似文献
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Ti基钎料在TiAl基合金表面上润湿性的研究 总被引:1,自引:0,他引:1
采用真空钎焊的方法,分别在910℃和1 000℃对37.5Ti- 37.5Zr-15Cu-10Ni 钎料在TiAl基合金表面上的润湿性进行研究,结果证明钎焊温度越高,该钎料的润湿性越好.分析表明在高温下该Ti基钎料润湿性的改善不仅仅与表面张力的降低有关,而且还与钎料和母材之间的反应密切相关. 相似文献