首次积分与临界情形运动稳定性

本文指出1946年苏联学者Четаев提出用首次积分的线性组合来构造李雅普诺夫函数后Четаев及其学生们解决保守系统的运动稳定性问题均用此方法.但是由于用试凑的方法解决起来比较麻烦,而且用他们的方法所得出的稳定性条件也不够完全,只能解决问题的纯虚根的情形,零根的情形却未考虑.本文提出利用降阶方法,也就是将微分方程通过消除循环坐标变换成标准形式,这样稳定性条件可直接由能量积分得出,用此方法计算起来不仅很简捷,而且零根情形亦可以考虑.因此对于具有两个循环坐标问题可以化成二阶系统并且很简捷地得到稳定性条件新结论.至于一个循环坐标问题,事实上Четаев及其学生们并未解决,例如外环为水平或任意角的陀螺仪的运动稳定性问题,但是用我们的方法却给出条件稳定与不稳定的条件.     

常微分方程数值方的法稳定性(英)

本文针对常微分方程数值方法稳定性问题，证明了一般方法的绝对稳定性定理，同时也指出了绝对稳定性条件的局限性．为了克服这种局限性，本文绘出了Jordan稳定性的概念，并建立了一个相应的判别定理．     

分段连续型随机微分方程指数Euler方法的稳定性

给出了线性分段连续型随机微分方程指数Euler方法的均方指数稳定性.经典的对稳定性理论分析,通常应用的是Lyapunov泛函理论,然而,应用该方程本身的特点和矩阵范数的定义给出了该方程精确解的均方稳定性.以往对于该方程应用隐式Euler方法得到对于任意步长数值解的均方稳定性,而应用显式Euler方法得到了相同的结果.最后,给出实例验证结论的有效性.     

常微分方程组的整体解及两点边值问题——Ⅱ.稳定性

本节讨论两点边值问题Ⅱ的一些性质,先证明 预备定理4.1 设Z为(l×m)阶非异矩阵,l≤m,则存在非异的l阶方阵R_z,使得Z_R=R_zZ为正交规范矩阵,且     

A new defect‐correction method for the stationary Navier‐Stokes equations based on pressure projection

A new defect‐correction method based on the pressure projection for the stationary Navier‐Stokes equations is proposed in this paper. A local stabilized technique based on the pressure projection is used in both defect step and correction step. The stability and convergence of this new method is analyzed detailedly. Finally, numerical examples confirm our theory analysis and validate high efficiency and good stability of this new method.     

Conditional Stability Estimates for Ill-Posed PDE Problems by Using Interpolation

The focus of this article is on conditional stability estimates for ill-posed inverse problems in partial differential equations. Conditional stability estimates have been obtained in related literature by a couple different methods. In this article, we propose a method called interpolation method, which is based on interpolation in variable Hilbert scales. We provide the theoretical background of this method and show that optimal conditional stability estimates are obtained. The capabilities of our method are illustrated by a comprehensive collection of different inverse and ill-posed PDE problems containing elliptic and parabolic problems, one source problem and the problem of analytic continuation.     

Numerical stability of DQ solutions of wave problems

In this paper, the solution of one-dimensional (1D) wave problems, by means of the Iterative Differential Quadrature method is discussed in terms of stability and accuracy. The 1D-wave equation with different boundary and initial conditions is considered. The time advancing scheme is here presented in a form, particularly suitable to support the discussion about stability both by the matrix method and by the energy method. The stability analysis, performed by means of these two methods, confirms the conditionally stable nature of the method. The accuracy of the solutions is discussed too.     

Analytical and numerical methods for the stability analysis of linear fractional delay differential equations

In this paper, several analytical and numerical approaches are presented for the stability analysis of linear fractional-order delay differential equations. The main focus of interest is asymptotic stability, but bounded-input bounded-output (BIBO) stability is also discussed. The applicability of the Laplace transform method for stability analysis is first investigated, jointly with the corresponding characteristic equation, which is broadly used in BIBO stability analysis. Moreover, it is shown that a different characteristic equation, involving the one-parameter Mittag-Leffler function, may be obtained using the well-known method of steps, which provides a necessary condition for asymptotic stability. Stability criteria based on the Argument Principle are also obtained. The stability regions obtained using the two methods are evaluated numerically and comparison results are presented. Several key problems are highlighted.     

无界可变延迟神经网络的一般稳定性(英文)

本文研究了无界延迟随机神经网络的稳定性,采用的主要技巧是Razumikhin方法,得到了p阶矩一般衰减率稳定性与几乎必然轨道一般衰减率稳定性.借助于M矩阵技巧使Razumikhin定理更便于应用.     

同心圆管间无粘可压缩旋转流动的稳定性研究

本文主要研究了两个同心圆管之间无粘可压缩旋转流动的稳定性问题.首先推导出了关于径向扰动速度分量的可压缩线化微分方程.利用类似于Ludwieg的分析方法,推导了可压缩旋转流的两个稳定性准则.然后用有限差分方法数值求解了本征值问题,给出了时间增长率,并验证了稳定性准则的正确性.最后讨论了压缩性对稳定性的影响.     

具有局部记忆阻尼的非均质Timoshenko梁的稳定性

该文研究的是具有一个局部记忆阻尼的非均质Timoshenko梁的稳定性. 在适当的假设条件下, 应用算子半群理论、乘子技巧结合频域方法的矛盾讨论, 证明了该系统是指数稳定的.     

Exponential stability of numerical solutions to a stochastic age-structured population system with diffusion

The main aim of this paper is to investigate the exponential stability of the Euler method for a stochastic age-structured population system with diffusion. The definition of exponential mean square stability of numerical method is introduced. It is proved that the Euler scheme is exponentially stable in mean square sense. An example is given for illustration.     

多参数多状态变量离散型有势非线性稳定问题的活化方法*

本文针对多参数变量和多状态变量的离散型有势系统的非线性稳定问题,提出了活化方法,导出了活化势函数和活化平衡方程.活化方法是弹性稳定理论中Liapunov-Schmidt方法的改进和提高,它比通常的摄动方法更加一般化、规范化.活化势函数可变换成标准突变势函数,活化平衡方程可作为分岔方程.本文的研究将促进弹性稳定理论与突变理论和分岔理论的结合.     

线性随机分数阶微分方程Euler方法的弱收敛性与弱稳定性

本文主要研究了线性随机分数阶微分方程Euler方法的弱收敛性与弱稳定性.首先构造了数值求解线性随机分数阶微分方程的Euler方法,然后证明该方法是弱稳定的和α阶弱收敛的,文末给出的数值算例验证了所获得的理论结果的正确性.     

非线性时变离散系统的稳定性

早在50年代,由于数字计算机在工程和科学上应用的增加,对控制理论家、经济学家以及生物学家来说,离散系统(差分方程)已经成为一个重要且有用的数学模型。因此,对离散系统的研究就越来越显得重要了.当时的工作主要是应用 Z 变换研究采样数据系统,近30多年来,离散系统的研究已经有了较大的发展,特别是离散系统稳定性方面更是如,     

局部资料下变分同化方法的稳定性研究

对于简化的一维扩散方程,在局部观测资料下,研究变分同化方法的稳定性.在变分同化中结合正则化方法,选择合适的正则化参数和稳定泛函,对预报模式进行修正,通过对预报精度进行先验估计,证明了该方法对于一维扩散方程的解的稳定性.修正补充相关计算结果,最后举出一个反例说明稳定性泛函的选取对于改进的变分同化方法实施的重要性.     

A novel approach on stabilization for linear systems with time-varying input delay

This paper presents new results on delay-dependent stability and stabilization for linear systems with interval time-varying delays. Some less conservative delay-dependent criteria for determining the stability of the time-delay systems are obtained in this paper. Based on the stability conditions, we propose a new state transformation technology to facilitate controller designing efficiently and computationally. The method is also applicable to the existing stability conditions reported by now, while the existing technologies may fail to derive computational control procedures from the stability conditions. Finally, some numerical examples well illustrate the effectiveness of the proposed method.     

一维波动方程联合反演的分步正则化法

本文只用一个纵波信息,对一维波动方程的速度和震源函数进行联合反演.并考虑到波动方程的反问题是一不适定问题,对震源函数和波速分别用正则化法分步迭代求解,大大减少了反问题的计算工作量,改善了该反问题的计算稳定性.为计算实际一维地震数据提供了一种方法.文中给出了只用一个反问题补充条件同时进行多参数反演的详细公式,并对相应的数值算例进行了分析和比较.     

多时滞退化微分系统指数稳定的代数判据

本文研究退化多时滞微分系统的指数稳定性,得到了退化多时滞微分系统指数稳定性的代数判据,给出的一个例子说明所得结果的应用,同时给出了中立型退化时滞微分系统指数稳定的判定方法.     

Unique Continuation on Quadratic Curves for Harmonic Functions*

The unique continuation on quadratic curves for harmonic functions is discussed in this paper. By using complex extension method, the conditional stability of unique continuation along quadratic curves for harmonic functions is illustrated. The numerical algorithm is provided based on collocation method and Tikhonov regularization.The stability estimates on parabolic and hyperbolic curves for harmonic functions are demonstrated by numerical examples respectively.