拟线性微分代数方程的标准形

讨论了拟线性微分代数方程在一类特殊的奇点-拟障碍点附近的标准形.通过矩阵广义逆理论,拟线性微分代数方程可化为半显式形式.然后运用标准形理论,在微分同胚变换下,给出了拟线性微分代数方程在拟障碍点附近的标准形.在此基础上进一步讨论了这类标准形的去奇异化性质.     

多项式微分代数系统的奇点性质

本讨论多项式微分代数方程的奇点性质，证明了经用吴方法整序后的系统的奇点与原系统的相应奇点有相同的鞍点性质。     

幂零奇点小邻域内相轨线的拓扑结构与中心问题

介绍幂零奇点小邻域内轨线的拓扑结构与中心问题的研究进展以及最近的一些结果.从三个方面来阐述这些结果:幂零奇点小邻域内相轨线的拓扑结构,幂零奇点的中心问题,幂零奇点的局部分支问题.也对幂零奇点的焦点量的计算方法进行了总结.     

利用衔接法构造奇摄动激波层问题的渐近解

研究了一类具有转向点的奇摄动拟线性边值问题,指出在一定条件下解在转向点t=0呈激波层现象.先用合成展开法构造出问题的形式近似,然后利用衔接法将t=0左、右两边分别具有边界层性质的近似式光滑地衔接起来,从而形成在t=0处具有激波层性质的解,并应用微分不等式理论证明了解的存在性及其渐近性质.     

具有初始缺陷弹性板的稳定性分析

本文以Marguerre方程为基础,用奇异性理论研究了初始挠度缺陷以及横向载荷对弹性板屈曲后分叉解的影响。借助于普适开折的原理,在单特征值局部邻域内将该问题的失稳分析转化为三次代数方程的讨论,从而确定出分叉解的性态。同时绘出了在不同参数下的分叉解文,讨论了几何缺陷和横向载荷对特征值的影响。     

关于具多项式系数的线性偏微分方程解的光滑性

§1定义了两类非正规的拟微分算子,并讨论了它们的映射性质;§2引进(?)-亚椭园性、F-亚椭园性及D-亚椭园性的概念,用以描述线性偏微分方程P(x,D)u=f的解的条件光滑性质,并对常系数情形得到了F-亚椭园性的条件:§3专门讨论具多项式系数的方程,收到了D-亚椭园性的某些充分条件。     

微分代数多项式系统的可解集

本文对一般微分代数方程给出了几类可解集的概念，并讨论了多项式微分代数方程的可解集，得到子多项式系统具有唯一解。特别是有多于一个的解的条件，并得到了低次多项式在一定意义下的充分必要条件。     

一阶拟线性偏微分方程组局部几何解的实现定理

用奇点理论研究一阶拟线性偏微分方程组,得到局部几何解的实现定理等结果.     

一阶拟线性偏微分方程组局部几何解的实现定理

用奇点理论研究一阶拟线性偏微分方程组,得到局部几何解的实现定理等结果.     

一类拟线性椭圆变分不等式解的存在性(英文)

考虑了一类p-Laplacian拟线性椭圆变分不等式问题,通过运用优化理论中的补偿法和Clark次微分性质,研究了这类椭圆变分不等式解的存在性.     

THE EXISTENCE AND UNIQUENESS OF THE SOLUTIONS OF DAES

1Intr0ducti0nDifferential-algebraicequations(DAEs)areveryusefu1inwidefields(cf.[1]).Bydifferential-algebraicequations,wemeanthoseequati0nswhosepartsof"derivative"cann0tbeexpressedexplicitly.Forexample,weconsidertheimplicitdifferentialequationwithmappingFsm00thssufficient1y.Itisusuallyreferredt0adifferential-algebraicequation(DAE)whentherank0fD.F(t,x,p)islessthann,wheretheremightbesomepurea1gebraic,whichwecallc0nstraintequations.TheDAEs,inparticular,theexistenceanduniquenessofitssolutions…     

Convex and Concave Relaxations for the Parametric Solutions of Semi-explicit Index-One Differential-Algebraic Equations

A method is presented for computing convex and concave relaxations of the parametric solutions of nonlinear, semi-explicit, index-one differential-algebraic equations (DAEs). These relaxations are central to the development of a deterministic global optimization algorithm for problems with DAEs embedded. The proposed method uses relaxations of the DAE equations to derive an auxiliary system of DAEs, the solutions of which are proven to provide the desired relaxations. The entire procedure is fully automatable.     

An efficient asymptotically correct error estimator for collocation solutions to singular index-1 DAEs

A computationally efficient a posteriori error estimator is introduced and analyzed for collocation solutions to linear index-1 DAEs (differential-algebraic equations) with properly stated leading term exhibiting a singularity of the first kind. The procedure is based on a modified defect correction principle, extending an established technique from the context of ordinary differential equations to the differential-algebraic case. Using recent convergence results for stiffly accurate collocation methods, we prove that the resulting error estimate is asymptotically correct. Numerical examples demonstrate the performance of this approach. To keep the presentation reasonably self-contained, some arguments from the literature on DAEs concerning the decoupling of the problem and its discretization, which is essential for our analysis, are also briefly reviewed. The appendix contains a remark about the interrelation between collocation and implicit Runge-Kutta methods for the DAE case.     

Local error estimates for moderately smooth problems: Part II—SDEs and SDAEs with small noise

The paper consists of two parts. In the first part of the paper, we proposed a procedure to estimate local errors of low order methods applied to solve initial value problems in ordinary differential equations (ODEs) and index-1 differential-algebraic equations (DAEs). Based on the idea of Defect Correction we developed local error estimates for the case when the problem data is only moderately smooth, which is typically the case in stochastic differential equations. In this second part, we will consider the estimation of local errors in context of mean-square convergent methods for stochastic differential equations (SDEs) with small noise and index-1 stochastic differential-algebraic equations (SDAEs). Numerical experiments illustrate the performance of the mesh adaptation based on the local error estimation developed in this paper. The first author acknowledges support by the BMBF-project 03RONAVN and the second author support by the Austrian Science Fund Project P17253.     

Delay-dependent stability of linear multistep methods for DAEs with multiple delays

This paper aims to investigate the asymptotic stability of linear multistep (LM) methods for linear differential-algebraic equations (DAEs) with multiple delays. Based on the argument principle, we first establish the delay-dependent stability criteria of analytic solutions; then, we propose some practically checkable conditions for weak delay-dependent stability of numerical solutions derived by implicit LM methods. Lagrange interpolations are used to compute the delayed terms. Several numerical examples are given to illustrate the theoretical results.     

Numerical Treatment of Second Order Differential-Algebraic Systems

We consider the numerical treatment of systems of second order differential-algebraic equations (DAEs). The classical approach of transforming a second order system to first order by introducing new variables can lead to difficulties such as an increase in the index or the loss of structure. We show how we can compute an equivalent strangeness-free second order system using the derivative array approach and we present Runge-Kutta methods for the direct numerical solution of second order DAEs. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Singularités de solutions d'équations aux dérivées partielles

We develop the general mathematical setting necessary to study the singularities of local solutions of the quasi-linear first-order systems of PDEs with a free initial condition. In the good cases, it is possible to describe these singularities as a function of the free initial conditions satisfied by the solutions. Using the transversality theorems, it is then possible to describe the singularities of generic solutions, and of generic families of solutions under deformation of the initial conditions. We apply this study by giving classifications of an important classe of hyperbolic quasi-linear first-order systems in the plane, the reducible systems, and of an almost general class of hyperbolic quasi-linear second-order equations in the plane.     

Stability Issues in Regular and Noncritical Singular DAEs

This paper addresses equilibrium stability issues in both regular and singular differential-algebraic equations (DAEs). We present a survey of available results and discuss some commonly-used methods in the qualitative analysis of low-index autonomous systems. Additionally, we extend the use of matrix pencil theory to the stability study of singular problems, pointing out some interesting relations between regular and singular DAEs. This framework is applied to the qualitative analysis of singular equations arising in the context of the Singularity Induced Bifurcation theorem, and also to the stability study of stationary equilibria in singular DAEs.