战斗机综合热能管理系统稳态仿真

建立综合热管理系统稳态仿真数学模型,在SIMULINK软件平台上搭建仿真模块,对系统同一高度不同马赫数及同一马赫数不同高度进行了稳态仿真,得到系统中关键部件的进出口温度和流量,并分析了马赫数以及高度变化对各状态点温度的影响。分析得出马赫数增加各状态点的温度基本是增加的,只有燃油冷却出口温度先减后增;各状态点的温度随高度的增高基本是减小的,只有燃油冷却出口温度是增加的。     

Charging of dust grains by anisotropic solar wind multi-component plasma

In this paper we study the charging process of small grain particles by anisotropic multi-component solar wind plasmas (electrons, protons and heavy ions), versus two-component (electron/proton) plasmas. We are focusing attention on the important characteristics of the charging process, namely the charging time, floating potential and current content as functions of plasma parameters such as He⁺⁺/H⁺ (α/p) number density and T_α/T_p temperature ratios of alpha particles to protons, as well as plasma streaming velocity v₀. Measured statistical properties of solar wind plasma parameters at 1 AU show considerable variations in α/p-temperature ratios from 1 to 10, in α/p-number density ratio from 0.01 to 0.35, as well as in values of streaming velocity v₀ from 200 km/s to 1000 km/s and more. Periods of these variations could last for several days each, leading to significant variability in the charging process, according to newly derived general analytical expressions. Numerical calculations performed for protons/alphas plasmas showed large disparity in the charging characteristics. For example, in anisotropic plasma, grain charging time varies up to 90% depending on α/p-particles temperature and number density ratios, whereas changes in floating potential are up to 40%. In contrast, in isotropic plasma, charging characteristic for grains do not change very much for the same plasma parameters variations, with charging time varying about 12% and floating potential only varying about 4%. It is also shown that in highly anisotropic plasma, with all ballistic electrons and ions, dust grains could not hold their charges, and characteristic discharged time is calculated. We note that the analysis is equally applicable to any sized body immersed in solar wind plasma.     

Kinetic theory of sheath formation in solar wind plasma

We present a general self-consistent kinetic theory for plasma sheath formation in solar wind plasma. The theory could be applied to anisotropic, as well as to isotropic collisionless plasma without resorting to any simplifications, limitations, or assumptions, such as the necessary existence of a ‘pre-sheath’ region of ions acceleration to ensure the Bohm criterion. The kinetic framework is first applied to sheath formation around an arbitrary oriented planar absorbing surface, charged by solar wind anisotropic plasma, under the condition of negligible photoelectric effect. We then make use of our kinetic approach for the plane geometry in isotropic collisionless plasma, as a particular case of a planar electrode orientation parallel to plasma streaming velocity, also analyzing the sheath structure around spherical and cylindrical absorbing electrodes submerged in isotropic collisionless plasma. Obtained results demonstrate principal differences in spatial charge distributions in sheath regions between spherical or cylindrical electrodes of large size and an unbound planar surface submerged in isotropic plasma. In the case of a planar electrode, we directly compare results obtained in our kinetic and hydrodynamic theories and conventional hydrodynamic theory of plasma sheath formation. The outcome from the present study have direct implications to the analysis of plasma sheath structure and associated distribution in space of charged dust grains, which is relevant to the moon exploration near the optical terminator region or in shadowed craters in the moon.     

星敏感器空间辐射效应研究

星敏感器作为一类高灵敏度光电集成部件,易受空间辐射的影响造成性能退化和工作 异常。分析星敏感器的辐射效应机理并制定相应的防护对策,既是当前可靠性增长的基础, 也是今后高性能星敏感器发展的必然要求,而国内尚缺少对这一问题的详细论述。阐述了空 间辐射环境和星敏感器的组成以及工作原理,综述分析了空间辐射效应机理和对星敏感器产 生的影响,并介绍了国外在相应防护对策上的经验,更进一步对影响星敏感器较为严重的瞬 态效应做了较为深入的探讨。
     

采用弱攻角补偿与脱敏设计的火星进入段制导

为提升火星进入段存在多种扰动时的制导末端精度,在现有三自由度脱敏设计的基础上,提出针对大气密度及升阻力系数波动的弱攻角补偿方法。通过攻角调整,协调升、阻力加速度测量值相对理论计算值的偏离程度,使加权形式的偏离程度指标趋近于1,从而降低气动参数波动对制导精度的影响。相平面分析和反证法证明了攻角调整过程的稳定性。蒙特卡洛仿真结果表明,该方法可达到较高的纵向末端状态精度。     

一种图像辅助火星着陆段自主导航方法

针对未来深空探测软着陆高精度实时导航的需求,提出了一种图像辅助的自主导航方案。首先通过下降段图像与落点区域地形匹配,获得着陆器相对于落点的位置和姿态;然后基于误差Kalman模型估计着陆器的状态误差,修正惯性导航的结果;在图像信息不可用的情况下,只进行惯性递推导航;这种方案既提高了导航的精度,也能保证实时性的要求。 数值仿真验证了该方案的可行性,该方案对未来实际工程任务具有很大的参考价值。     

飞机电磁环境效应的特性及控制

从飞机设计中电磁环境效应基础专业的技术领域和专业构成的演变出发,本文系统地介绍了电磁环境效应的特性以及与飞机使用和安全的关系,重点论述了飞机研制中来自电磁环境效应的威胁及其控制措施。     

无人机路径规划中的环境和威胁模型研究

为了提高无人机执行任务时的突防能力,在进行飞行路径规划时必须对战场环境中的威胁环境进行评估,而威胁环境中的威胁估计与飞机被雷达或类似的传感器探测出的风险度有关,需要考虑的信息包括无人机传感器范围内的威胁位置和强度.路径规划算法依赖于路径规划空间的建模方式,包括环境建模和威胁源建模.目前针对规划空间环境和威胁模型的建模方法缺乏系统分类和论述.分析了战场环境的建模方法,研究了规划空间的离散建模方式,根据无人机飞行过程中可能遭遇的威胁类型进行威胁源类型的划分,并针对三种威胁类型分别建立威胁风险模型,为无人机在复杂环境下的路径规划实现做了参数准备.     

高动态环境下惯组辅助GNSS接收机卫星导航信号的捕获

针对高动态环境下多普勒频移超出了接收机的搜索范围接收机无法捕获卫星导航信号这一问题,提出了利用INS辅助GNSS接收机卫星导航信号捕获的方法.该方法利用INS提供的载体位置、速度信息,并结合通过卫星星历(或历书)得到的卫星位置、速度估算载波多普勒频移,利用估算的载波多普勒频移重新设定GNSS接收机载波搜索中心频率,使G...     

泛在图书馆与高校图书馆员

泛在图书馆是图书馆新的发展方向,泛在知识环境的到来,将使图书馆社会地位和整体功能发生巨变。通过对泛在图书馆及高校图书馆员未来的展望,强调图书馆馆员职业需要危机意识、责任意识和创新意识。阐述泛在图书馆、泛在知识服务对图书馆员知识结构与专业能力的要求,提出要提高图书馆员综合素质,以适应未来社会的挑战。