基于变差的遥测天线跟踪稳定度研究*

对遥测系统伺服跟踪数据进行处理,分析对比几种跟踪方式,指出几种跟踪方式中可能存在的问题,并提出相应的改进措施。同时,通过曲线变差、方差的属性分析,研究自主跟踪时天线俯仰、方位的稳定度与跳变程度,并与理论弹道、数字引导方式的曲线稳定度进行分析和对比,得出变差越大稳定度越差,方差越大异常跳变越明显的结论。     

绳系卫星系统周期运动的分岔与镇定

考虑到绳系卫星系统主星姿态的作用,研究状态保持阶段绳系卫星系统的非线性动力学。首先建立含姿态的绳系卫星姿-仰耦合两自由度非线性动力学模型,通过摄动法解析地获得系统的周期运动,利用Floquet理论分析轨道偏心率对该周期运动稳定性的影响。然后,通过与姿态有关的两个系统参数,对绳系卫星系统周期运动的分岔进行了数值仿真。结果表明,姿态和俯仰运动耦合导致绳系卫星系统产生多个概周期运动并存的复杂动力学行为以及混沌运动。最后,为将混沌运动引导到某个稳定的周期运动上,提出利用线性速度反馈的镇定策略。     

球面密封结构密封状态的力学分析及验证

针对卫星推进系统管路中经常使用的球面密封结构,分析了其密封的机理,讨论了塑性变形对金属密封的重要作用。在此基础上,采用非线形有限元法对其进行了弹塑性分析和接触分析,得出了拧紧力矩和密封状态的对应关系,并通过实验验证了分析方法的准确性。     

环境模拟舱体的建模仿真及控制方法

环境试验时需要精确控制环境模拟舱体内的温度以满足军标要求,同时为了解决环境模拟舱体内加热过程中升温速率与控制精度之间的矛盾,在对其温度变化进行动态特性分析与建模的基础上,提出采用专家控制策略控制环境模拟舱内的温度,并对其控制效果进行了仿真研究.仿真结果与现场运行调试结果均表明:专家控制方法具有无超调、响应速度快、稳态精度高、加温效率明显的优点,是可行和有效的;与试验数据相比,建立的传热模型和控制系统模型具有较高的准确性,符合实际情况.这种建模仿真及控制方法为实际过程中研究控制规律提供了有力的参考和帮助,对研究类似问题具有深远意义.      

Initial characterization of the microgravity environment of the international space station: increments 2 through 4

The primary objective of the International Space Station (ISS) is to provide a long-term quiescent environment for the conduct of scientific research for a variety of microgravity science disciplines. This paper reports to the microgravity scientific community the results of an initial characterization of the microgravity environment on the International Space Station for increments 2 through 4. During that period almost 70,000 hours of station operations and scientific experiments were conducted. 720 hours of crew research time were logged aboard the orbiting laboratory and over half a terabyte of acceleration data were recorded and much of that was analyzed. The results discussed in this paper cover both the quasi-steady and vibratory acceleration environment of the station during its first year of scientific operation. For the quasi-steady environment, results are presented and discussed for the following: the space station attitudes Torque Equilibrium Attitude and the X-Axis Perpendicular to the Orbital Plane; station docking attitude maneuvers; Space Shuttle joint operation with the station; cabin de-pressurizations and the station water dumps. For the vibratory environment, results are presented for the following: crew exercise, docking events, and the activation/de-activation of both station life support system hardware and experiment hardware. Finally, a grand summary of all the data collected aboard the station during the 1-year period is presented showing where the overall quasi-steady and vibratory acceleration magnitude levels fall over that period of time using a 95th percentile benchmark.     

自硬树脂砂型的开裂原因及防止措施

简述了冷硬树脂砂型在某些情况下的产生开裂的原因及机理,讨论了几种解决的方法,有利于改进产品质量,减少双方的经济损失.     

叠氮粘合剂推进剂热分解及燃烧性能研究综述

综述了叠氮类粘合剂ＧＡＰ，ＢＡＭＯ和ＡＭＭＯ的热分解及共推进剂的燃烧性能，认为叠氮类推进剂中－Ｎ３基受热易分解，因而基础燃速高，燃速温度敏感性大；在配方中引入有效的添加剂，可提高该类推进剂的燃速，降低其压强度指数。     

用动态分析法表征复合推进剂偶联剂的作用效果

研究了偶联剂对复合推进剂动态力学损耗的影响。建立了一种动态力学分析方法，即通过建立过渡相模型和引入表征因子Ａ，分别在ＨＴＰＢ和聚醚两种体系的复合推进中评价了偶联剂的作用效果。结果表明，天征因子Ａ值越低，偶联剂在该温度范围内的作用效果越好，该结论为表征复合推进剂关剂的作用效果提供了一种新的方法。     

Taking stock of Europe's developing space policy: from the European space policy workshops to the European space policy forum

A series of workshops designed to make up for the lack of high-level, informal discussion of European space policy has been running—with a gap during formulation of the EC Green/White Paper on this subject—since September 2002. In view of the progress made in establishing a coherent European strategy, and of various other recent events, such as China's entry into the human spaceflight field, the organizers intend not only to continue the series but also to establish a more permanent, research-oriented European Space Policy Foundation (ESPF). Following a report on the proceedings of the third workshop, held in September 2003, which covered developing an overall European policy, new applications (Galileo and GMES) and human spaceflight, the authors set out a proposal for an ESPF and present the six major research themes it would aim to investigate.     

关于普通高校体育教学的思考

通过对高校体育教学中的教学模式、内容设制、考核形式几方面的分析、探讨，提出了高校体育教学应以未来社会人才的需要为出发点，使体育教学从根本上摆脱传统教学观念的束缚，从单纯培养“知识型”、“技能型”人才向培养“创造性”、“综合性”、“应用性”人才转变。