具无穷时滞的中立型Volterra积分微分方程的概周期解

研究了一类具无穷时滞的中立型Volterra积分微分方程的概周期解问题．利用线性系统指数型二分性理论和泛函分析方法,得到了一些关于该方程的概周期解的存在性、唯一性与稳定性的新结果,推广了相关文献的主要结果．     

中立型泛函微分方程周期解问题

利用Fourier级数理论研究了一类k-阶线性中立型泛函微分方程周期解问题,给出了周期解存在唯一性的充要条件。利用此结果并结合Schauder不动点原理,进一步研究了一类k-阶非线性中立型泛函微分方程,得到了存在周期解的新的结果。这些结果改进和推广了近期文献中的已有结论。     

一类具多偏差变元的高阶中立型微分方程周期解的存在唯一性

利用重合度理论,研究了一类具多偏差变元高阶中立型泛函微分方程的周期解,获得这类方程至少存在和至多存在一个T-周期解的充分性条件,其中周期解的先验界估计与方程的滞量有关.文中的主要结果改进和推广了相关文献的主要定理.     

多时滞中立型微分积分方程的周期解

研究了一类具有多个时滞的中立型微分积分方程x'(t)=∫tt-σ9(t,s,x(s))ds f(t,x(t-τ0),x'(t-τ1))周期解的存在性,得到了方程周期解存在的充分条件.所得结果体现了滞量σ对周期解存在性的影响.     

具无穷时滞高阶中立型微分方程的周期解

利用重合度理论研究了一类具有无穷时滞高阶中立型泛函微分方程周期解的存在性,获得了该方程存在周期解的充分条件,推广和改进了二阶方程的相应结果.     

一类高阶中立型方程的周期解

利用Fourier级数理论讨论了一类高阶中立型方程的周期解问题。所得结果改进了司建国(应用数学和力学,第17卷1期:关于高阶常系数中立型方程周期解的讨论)的主要结果,即将该文定理1的条件|b₀|<1/2改为|b₀|≠1,从而该文的其它定理也可相应得到改进。     

二阶具有非正系数的NFDE与RFDE的非振动解类型与判别

本文讨论二阶具有非正系数的中立型与滞后型泛函微分方程,给出了这些方程的非振动解的类型以及判别条件。 对于cO情形(中立型),本文给出了四种S~*类的非振动解:对于|c|相似文献   

具逐段常变量中立型时滞微分方程的概周期解

通过构造二阶差分方程的概周期序列解，研究了中立型时滞逐段常变量微分方程概周期解的存在性．     

一类推广的干摩擦问题周期解的存在性

为了得到干摩擦问题存在周期解的判断方法,利用微分包含理论对系统+k~2x+μSngp(t)+T(t)a.e.进行了讨论.在周期外力p(t)周期等于固有周期2π/R的情形下得到了周期解存在的充要条件,在周期外力p(t)周期不等于固有周期整数倍2nπ/R的情形下得到了周期解存在的充分条件.     

一阶中立型泛函微分方程解的渐近性与振动性

本文研究具有变系数和多偏差的一阶中立型微分方程，讨论了方程的非振动解的渐近性，得到了方程振动的充分判据，其中有些是变号系数的情形．     

Uniqueness of Self-Similar Solutions to the Network Flow in a Given Topological Class

This paper deals with the uniqueness, within a fixed topological class, of “tree-like” solutions to the evolution of networks by curve shortening flow. More precisely, we show that if for a given initial condition, there is a solution to the network flow that is tree-like and regular for positive times, then this solution is unique within its topological class. The result in particular applies to expanding self-similar solutions. The proof is based on the following Allen–Cahn approximation result: every regular tree-like solution to the network flow can be realized as the nodal set of a family of solutions to the Allen–Cahn equation. Then, the main result of this paper follows from the uniqueness of the “ε-level” solutions. The results in this paper deal only with uniqueness of solutions. The existence of solutions for the general class of initial conditions that we consider in this paper is unknown in most cases.     

A comparison theorem for a piecewise Lipschitz continuous Hamiltonian and application to Shape-from-Shading problems

Summary The reconstruction from a shaded image of a Lambertian and not self-shadowing surface illuminated by a single distant pointwise light source may be written as a first-order Hamilton-Jacobi equation.In this paper, we continue the investigation begun in E. Rouy and A. Tourin into the uniqueness of the solution of this equation; the approach is based on the viscosity solutions theory and the dynamic programming principle.More precisely, we concentrate here on the uniqueness of the viscosity solution of this equation in case the measured luminous intensity reflected by the surface is discontinuous along a smooth curve. We prove a general comparison result for a piecewise Lipschitz continuous Hamiltonian and illustrate it by numerical experiments.     

概周期系统概周期解的存在唯一性

应用构造Ляпунов函数的方法，讨论了非线性微分方程系概周期解的存在唯一性.同时给出了Liénard方程存在唯一概周期解的一组充分条件.     

分数阶微分方程的一些新结果

第一部分,介绍分数阶导数的定义和著名的Mittag—Leffler函数的性质．第二部分,利用单调迭代方法给出了具有2序列Riemann—Liouville分数阶导数微分方程初值问题解的存在性和唯一性．第三部分,利用上下解方法和Schauder不动点定理给出了具有2序列Riemann—Liouville分数阶导数微分方程周期边值问题解的存在性．第四部分,利用Leray—Schauder不动点定理和Banach压缩映像原理建立了具有n序列Riemann—Liouville分数阶导数微分方程初值问题解的存在性、唯一性和解对初值的连续依赖性．第五部分,利用锥上的不动点定理给出了具有Caputo分数阶导数微分方程边值问题,在超线性（次线性）条件下C310,11正解存在的充分必要条件．最后一部分,通过建立比较定理和利用单调迭代方法给出了具有Caputo分数阶导数脉冲微分方程周期边值问题最大解和最小解的存在性．     

A model for resistance welding including phase transitions and Joule heating

In this paper, we introduce a new model for solid–liquid phase transitions triggered by Joule heating as they arise in the case of resistance welding of metal parts. The main novelties of the paper are the coupling of the thermistor problem with a phase‐field model and the consideration of phase‐dependent physical parameters through a mixture ansatz. The PDE system resulting from our modeling approach couples a strongly nonlinear heat equation, a non‐smooth equation for the the phase parameter (standing for the local proportion of one of the two phases) with a quasistatic electric charge conservation law. We prove the existence of weak solutions in the three‐dimensional (3D) case, whereas the regularity result and the uniqueness of solution is stated only in the two‐dimensional case. Indeed, uniqueness for the 3D system is still an open problem. Copyright © 2011 John Wiley & Sons, Ltd.     

Iterative method for a class of fourth-order p-Laplacian beam equation

This paper considers the existence of the solutions for a class of fourth-order $p$-Laplacian. The boundary value problem considered can describe the tiny deformation of an elastic beam. By using a novel efficient iteration method, the existence and uniqueness result of solution for the problem is obtained. An example is given to illustrate the main results.     

General problems of explicit integration of differential inequalities

We consider the problem of the explicit search for all solutions of a first-order nonstrict differential inequality. We use the formula of the general solution of the corresponding differential equation. Using an analog of the method of arbitrary constant variation or, in other words, a straightening diffeomorphism, we reduce the original inequality to the simplest form ? ≤ 0 or ? ≥ 0. Even if the equation is considered in the existence and uniqueness region, theoretical and practical problems arise. The first problem is related to the extension of solutions (i.e., to the interval of determination). The second problem is that the general solution may consist of several functions given on different intervals of the equation domain. As a result, the resulting inequality also may have a solution that is composed of different functions. The situation becomes more complicated when the equation has points of branching. In this case, the method of comparison of theorems cannot be used. In this paper, we describe a method for solving differential inequalities and estimating their solutions for this case as well. The result obtained in this study provides a unified approach to many theorems on differential inequalities available in the literature.     

EXISTENCE AND UNIQUENESS OF WEAK SOLUTIONS FOR TWO-DIMENSIONAL MODIFIED NAVIER-STOKES EQUATIONS

This paper studies a two-dimensional modified Navier-stokes equations. The author shows the existence and uniqueness of weak solutions for this equation by Galerkin method in bounded domains. The result is further extended to the case of unbounded channel-like domains.     

On a Finite Difference Scheme for an Inverse Integro-Differential Problem Using Semigroup Theory: A Functional Analytic Approach

In this article, the problem of reconstructing an unknown memory kernel from an integral overdetermination in an abstract linear (of convolution type) evolution equation of parabolic type is considered. After illustrating some results of the existence and uniqueness of a solution for the differential problem, we study its approximation by Rothe's method. We prove a result of stability and another concerning the order of approximation of the solution in dependence of its regularity. The main tool is a maximal regularity result for solutions to abstract parabolic finite difference schemes. Two model problems to which the results are applicable are illustrated.     

分数布朗运动驱动下z一致连续的BSDE解的存在性与唯一性

本文研究一类由分数布朗运动驱动的一维倒向随机微分方程解的存在性与唯一性问题,在假设其生成元满足关于y Lipschitz连续,但关于z一致连续的条件下,通过应用分数布朗运动的Tanaka公式以及拟条件期望在一定条件下满足的单调性质,得到倒向随机微分方程的解的一个不等式估计,应用Gronwall不等式得到了一个关于这类方程的解的存在性与唯一性结果,推广了一些经典结果以及生成元满足一致Lipschitz条件下的由分数布朗运动驱动的倒向随机微分方程解的结果.