重根特征向量导数计算的特殊迭代法

在重根特征向量导数计算方法的发展中，为了从无限个特解中确定出唯一的通解，提出过不同定解条件，但正确定解条件是唯一的。员后公认的定解条件为Z^TMZ Z^TMZ=-Z^TMZ,这里认为Z^TMZ≠Z^TMZ，由此便引出物理短阵(刚度阵和质量阵)的二阶导数。为了避免物理阵二阶导数的计算，本文在满足前述定解条件的前提下，利用一种特殊的迭代格式回避了物理阵二阶导数的引入。同时该迭代过程可直接获得通解，不同于目前流行的做法：先由一个不定支配方程求其特解，然后才由定解条件确定通解。另外，数值表明，动柔度迭代式的精度可与直接迭代式相匹敌，可是动柔度迭代式用于许多特征向量导数计算时，却省时得多。     

求解一维非线性守恒律的一类MmB差分格式

本文构造了一维非线性双曲型守恒方程的一类ＭｍＢ差分格式,并推广到方程组情形。数值计算结果表明,格式具有高分辨率且不会产生数值为振荡。     

RELATIONSHIPS FOR MOTION DESCRIBED IN ANY TWO ROTATIONAL REFERENCE FRAMES

In this paper the definitions of the relative derivatives of a vector with respect to time in any reference frame by using the notation of vectrix are proposed. It is further shown that with the help of vectrix one can treat the relative derivatives more clearly and more rigorously when multiple reference frames are concerned. Very useful relationships between the first order relative derivatives described in any two reference frames are derived. Relationships for the second order relative derivatives are also presented in detail. A new concept called "rotation induced acceleration" which is caused by the rotation of two reference frames when motion is necessarily described in them is presented. The result obtained in this paper is the generalization of the acceleration theorem given in conventional theoretical mechanics.     

基于摄动理论的爆高确定方法研究

分别讨论了两种通过飞行时间确定爆高的方法:解析计算修正法和时间偏导数法,这两种方法都是通过计算延迟时间来确定爆高,具有自主性强、可靠性高的特点。计算了两种方法在不同干扰条件下的结果,分析了造成计算偏差的原因。计算结果表明,两种方法的计算误差都非常小,均可应用于弹道导弹爆高确定。     

衍生金融工具对传统会计的冲击

衍生金融工具应运而生，但却无法在传统会计信息系统中反映，致使投资者在会计信息的占有与使用上严重不对称，无法作出最优决策。本文围绕衍生金融工具对传统会计要素、会计确认标准、会计计量基础以及会计报告的冲击，提出了基本的应对措施。     

Ion-acoustic waves in unmagnetized collisionless weakly relativistic plasma of warm-ion and isothermal-electron using time-fractional KdV equation

Collisionless unmagnetized plasma consisting of a mixture of warm ion-fluid and isothermal-electron is considered, assuming that the ion flow velocity has a weak relativistic effect. The reductive perturbation method has been employed to derive the Korteweg–de Vries (KdV) equation for small – but finite-amplitude electrostatic ion-acoustic waves in this plasma. The semi-inverse method and Agrawal’s method lead to the Euler–Lagrange equation that leads to the time fractional KdV equation. The variational-iteration method given by He is used to solve the derived time fractional KdV equation. The calculations show that the fractional order may play the same rule of higher order dissipation in KdV equation to modulate the soliton wave amplitude in the plasma system. The results of the present investigation may be applicable to some plasma environments, such as space-plasmas, laser-plasma interaction, plasma sheet boundary layer of the earth’s magnetosphere, solar atmosphere and interplanetary space.     

多操纵面飞翼构型飞机舵面故障在线诊断方法

舵面故障会影响飞机的操纵性,为实现飞机的控制重构需在线诊断出舵面的故障信息.针对多操纵面飞翼构型飞机,提出了一种在线诊断其舵面故障的方法.飞翼构型飞机舵面故障在线诊断需辨识的操纵导数个数较多,直接使用最小二乘法难以精确辨识得到各操纵导数.基于限定记忆最小二乘法,采用分组辨识法对飞机的操纵导数进行辨识,减少了每次辨识操纵...     

Inversion of satellite gradiometry data using statistically modified integral formulas for local gravity field recovery

The satellite gravity gradiometric data can be used directly to recover the gravity anomaly at sea level using inversion of integral formulas. This approach suffers by the spatial truncation errors of the integrals, but these errors can be reduced by modifying the formulas. It allows us to consider smaller coverage of the satellite data over the region of recovery. In this study, we consider the second-order radial derivative (SORD) of disturbing potential (T_rr) and determine the gravity anomaly with a resolution of 1° × 1° at sea level by inverting the statistically modified version of SORD of extended Stokes’ formula. Also we investigate the effect of the spatial truncation error on the quality of inversion considering noise of T_rr. The numerical investigations show satisfactory results when the area of T_rr coverage is the same with that of the gravity anomaly and the integral formula is modified by the biased least-squares modification. The error of recovery will be about 6 mGal after removing the regularization bias in the presence of 1 mE noise in T_rr measured on the orbit.     

基于气动参数之间关系的桥梁断面气动导纳识别

气动导纳的准确估计对大跨桥梁抖振分析具有重要意义.目前在识别方法、试验技术等方面均有诸多进展,但尚未建立识别全部气动导纳函数的方法.针对这一问题,基于气动导数与气动导纳之间的关系,结合根据紊流风场中的抖振响应同时识别桥梁结构气动导数和气动导纳这一思路,首先采用随机子空间法识别得到紊流风场中桥梁结构的气动导数,然后利用气动导数与气动导纳之间的近似关系获取与竖向脉动风分量对应的气动导纳函数,最后根据抖振力谱和脉动风速谱来确定与水平向脉动风分量对应的气动导纳函数.实例研究表明,本文方法对流线型断面气动导纳的识别是可行的.     

航空泵试验台驱动变结构控制

飞机液压系统泵源需进行地面试验,采用变频调速器＋异步电机＋增速箱的驱动形式是航空泵进行地面试验最先进有效的方法之一.建立了矢量控制变频调速驱动下航空泵试验台驱动系统的数学模型,针对航空泵试验时由于负载变化泵转速不能保持恒定的问题,采用积分滑模面的滑模变结构控制策略,并构造Lyapunov函数证明其稳定性.为降低输出抖振现象,提出采用模糊控制监督下的滑模变结构控制和伪微分反馈(PDF, Pseudo Derivative Feedback)控制相结合的控制策略,仿真及实验结果表明,该控制方法有很高的控制精度,在保持滑模变结构控制鲁棒性强的前提下降低了输出抖振现象.