柔性航天器动力学建模的伪坐标形式Lagrange方程

航天器动力学建模过程中，常采用伪坐标形式Lagrange方程。文章针对多柔体航天器的情况，利用Hamilton原理，导出了柔性航天器动力学建模的伪坐标形式Lagrange方程，并由此建立了由中心体和柔性附件组成的全柔性航天器的动力学方程。     

Evolution of an electron beam pulse influenced by coulomb collision effects in the solar corona

Electrons accelerated in the corona during solar activity give rise to radio emission events that can be observed over a wide range of frequencies. Among different finer-scale structures in the dynamic spectra observed in the radio range, fast transients with extents of some milliseconds known as solar radio spikes are observed accompaning the background continuum emission. Fundamental to the generation of radio spikes is a propagating electron beam and following its evolution allows us to understand the physical processes occurring in the solar corona. With the use of a numerical Fokker–Planck code we follow a previous numerical study to simulate the propagation of an electron beam pulse injected in a small region at the top of a magnetic field and outwards the solar corona under typical flare conditions. It was found that in large ambient densities of ${10}^{10}$ cm⁻³ at the injection point, Coulomb collision effects have an important effect on the propagation of the electrons, causing that the injected electrons thermalize faster in a time of $0.1$ and $0.4$ s for an electron distribution with a low-energy cut off of 16 and 7 keV respectively and a spectral index of 3. For a tenous ambient medium of density ${10}^9$ cm⁻³ thermalization occurs only for an electron distribution with smaller low-energy cut off (7 keV) with a duration of $\approx$1.5 s, while for a larger low-energy cut off (16 keV) the loss of accelerated electrons is very slow, regardles of the spectral index ($3,7$). The electron loss time by Coulomb collisions, which depends on the low boundary ambient density, might be an important parameter that influences the generation of radio spikes due to the formation of instabilities in the corona.     

摆式陀螺罗盘的运动特性及其分析

从陀螺力学的经典理论出发,建立了摆式陀螺罗盘的力学模型,推导出了具有重力约束的二自由度陀螺的运动方程,以此为基础,分析了摆式陀螺罗盘在阻尼及干扰条件下的运动,给出了干扰对摆式陀螺罗盘的影响的函数表达。     

基于H∞／LTR转子磁通观测器的异步电机调速系统

讨论了一种基于Ｈ∞／ＬＴＲ磁通观测器的异步电机调速系统的设计方法，提出了将Ｈ∞／ＬＴＲ过程应用于异步电机调速系统的磁通估计问题中。首先对Ｈ∞／ＬＴＲ状态观测器的设计方法、存在条件进行了分析，然后讨论了异步电机调速系统和Ｈ∞／ＬＴＲ磁通观测器的设计过程，最后给出了仿真结果。     

Riccati方程的二次代数曲线解

Ｒｉｃｃａｔｉ方程一般没有初等解，但当它有初等解时，解很可能是代数曲线解。给出了Ｒｉｃｃａｔｉ方程存在二次代数曲线解的充要条件，及其有效的求解方法。     

关于二阶马尔可夫过程的样本序列是否存在无后效性的讨论

本文指出了工程界关于高阶马尔可夫过程的一个错误定义,证明了(p=2)满足这个定义的平稳高斯过程是不存在的。 本文还指出由二阶微分方程 x″(t) a_1x′(t) a_2x(t)=ε(t) (其中ε(t)是白高斯过程)描写的随机过程x(t)的任意均匀采样序列都不能是AR(2)序列,而由下面微分方程 x″(t) a_1x′(t) a_2x(t)=ε′(t) βε(t)描写的随机过程x(t),当β~2>[max(c_1~2,c_2~2)]时(c_1、c_2是特征方程z~2 a_1z a_2=0的根),至少存在一个采样间隔Δ_1,使相应的样本序列是AR(2)模型,因此是一个二阶广义马尔可夫序列。     

战斗机的体系对抗分析

Analyses of the systematic confrontation between two military forcfes are the highest hierarchy on opera-tional effectiveness study of weapon systema.The physi-cal model for tactical many-on-many engagements of an aerial warfare with heterogeneous figher aircraft is estab-lished.On the basis of Lanchester multivariate equations of square law,a mathematical model corresponding to the established physical model is given.A superiorityh parame-ter is then derived directly from the mathematical model.With view to the high -tech condition of modern war-fare,the concept of superiority parameter which more well and truly reflects the essential of an air-to-air en-gagement is further formulated.The attrition coeffi-cients,which are key to the differential equations,are de-termined by using tactics of random target assignment and air-to-air capability index of the fighter aircraft.Hereby,taking the mathematical model and superiority parameter as cores,calculations amd analyses of complicate systemic problems such as evaluation of battle superiority,prog-mostication of combat process and optimization of colloca-tions have been accomplished.Results indicate that a clas-sical combat theory with its certain recent development has received newer applications in the military operation research for complicated confrontation analysis issues.     

GHOST FLUID METHOD FOR RICHTMYER-MESHKOV INSTABILITY SIMULATION

INTRODUCTIONThe energy of the Richtmyer- Meshkov in-stability is excited by the interaction between ashock wave and a contact interface across thatfluids are different.Itis very important thatcap-ture the interface in multi- material flows exact-ly.Here we will apply the ghost fluid method tosimulate two dimensional Richtmyer- Meshkovinstability.The mathematical equation used to simulatethe Ritchmyer- Meshkov instability is the com-pressible Euler equation for two ideal gases.ρρuρvE…     

Lyapunov矩阵方程的一种解法

本文提供了求解Lyapunov矩阵方程的一个新算法。首先,对系数矩阵具有Frobenius形式的方程给出了一种公式解法。然后通过对系数矩阵的约化,将解法推广列一般情形。最后,给出了数值例子,并同有关的方法进行了比较。     

TVD格式计算一维Euler方程间断解存在的几个理论问题

本文讨论了TVD格式按本文第二节A段意义推广到拟线性方程组的几个理论问题。指出:1.对于Riemann间断分解,Euler方程的解和Riemann不变量都没有TVD性质,因此不能将TVD格式自然推广;2.TVD格式是提高分辨率的一种途径,它不能保证得到物理解,能得到物理解的TVD格式一定是耗散守恒格式,因此将TVD格式推广时,必须保证格式是耗散的,否则仍会得到非物理解。并给出了一阶迎风格式,TVD2,UNO2得到的若干非物理解算例;3.非物理解现象只是发生在具有剧烈膨胀的单波区的计算上,而某些TVD格式若会得到非物理解,则一定发生在特征值变号的单波区的计算上。