一类带奇异系数椭圆方程解的存在性

本文运用变分方法及Hardy不等式讨论了一类带奇异系数的临界椭圆方程，证明了在一定条件下方程解的存在性。     

一类非线性椭圆方程正解的存在性

研究了一类非线性椭圆方程. 应用改进型Hardy不等式和变分方法, 证明了在一定条件下方程正解的存在性.     

一类含临界耦合非线性项的奇异椭圆方程组的正解

本文研究了一类含临界指数与耦合非线性项的奇异椭圆方程组. 利用变分方法与极大值原理, 通过证明对应的能量泛函满足局部的 (PS)c 条件, 得到了这类方程组正解的存在性, 推广了单个方程与方程组中的相应结果.     

带非齐次项和Sobolev Hardy临界指数的奇异椭圆方程的多解

该文讨论一个带非齐次项和Sobolev Hardy临界指数的半线性奇异椭圆型方程的多解问题. 证明了当方程中的参数小于某个已知的常数时，所考虑的问题有两个解     

弱Hardy空间上的参数型Marcinkiewicz积分

证明了参数型Marcinkiewicz积分μΩ^p是（H^p,∞ , L^p,∞）（0〈p≤1）型的算子，这里Ω是满足Lipα条件的R^＊上的零次齐次函数．对于p=1，减弱了Ω的条件μΩ^p得到μΩ^p是（H^1,∞ , L^1,∞）型的．作为上述结果的推论，得到了μΩ^p是弱（1，1）型的算子．     

关于双特征Beltrami方程

该文研究空间Ｂｅｌｔｒａｍｉ方程的推广形式，即双特征Ｂｅｌｔｒａｍｉ方程．利用外微分形式与矩阵的外代数等工具，将双特征Ｂｅｌｔｒａｍｉ方程转化为一个非齐次的狆 调和方程，转化过程中只用到加于特征矩阵的一致椭圆型条件．然后验证了算子犃满足的条件：Ｌｉｐｓｃｈｉｔｚ型条件、单调不等式、齐次性条件以及算子犅满足的控制增长条件．并利用得到的狆 调和方程，给出了双特征Ｂｅｌｔｒａｍｉ方程广义解分量函数的弱单调性结果．     

平面中含Hardy位势临界参数的非线性椭圆型方程

本文首先证明了平面中含Hardy位势和临界参数的非线性椭圆方程在一个新Hilbert空间中无穷多个解的存在性,然后在该空间中还讨论了一类含Hardy位势的变分问题极小解的存在性．     

关于多项式的Waring问题（Ⅱ）

设ｆ＿ｌ（ｘ）是首项系数为正的ｌ次整系数多项式，满足条件：不存在整数ｄ，ｑ＞１使得ｆ＿ｌ（ｘ）≡ｄ（ｍｏｄｑ）对所有ｘ成立．记Ｒ＿ｋ（ｎ）为方程的正整数的解数，本文的主要结果是：对于及充分大的ｎ，我们有Ｒ＿ｋ（ｎ）》这是Ｖａｕｇｈａｎ关于Ｗａｒｉｎｇ问题的一个结果对多项式的推广。     

确定曲线方程变量范围的几种常用方法

求满足某种条件的动点轨迹方程是解析几何的基本问题之一．具有某种条件的一切点，它的坐标应都是所求方程的解，因此在解题中常需讨论曲线方程的变量范围，去掉那些不满足条件的点，找回满足条件的点，使得曲线上所有的点都适合这个条件．下面通过实例例析几种确定曲线方程中变量范国的方法．1利用已知条件确定范围y2＝1（y≥0）上动点P，F为右焦点，正方形FPQM的顶点顺时针排列，求M点的轨迹方程．0），设M（x，y），易求得P点的坐标为代入,求得方程为由已知条件y≥0，所以，因此所求方程中变量x的范围是．2利用构成几何图形条件确定…     

含Hardy位势的非线性Schr?dinger-Poisson方程的正规化解

本文考虑一类含Hardy位势的非线性Schr?dinger-Poisson方程.在适当的参数假设条件下,我们应用约束变分方法证明了正规化解的存在性,推广了有关文献的结果.     

The uniqueness of a solution to the inverse Cauchy problem for a fractional differential equation in a Banach space

We consider linear fractional differential operator equations involving the Caputo derivative. The goal of this paper is to establish conditions for the unique solvability of the inverse Cauchy problem for these equations. We use properties of the Mittag-Leffler function and the calculus of sectorial operators in a Banach space. For equations with operators in a general form we obtain sufficient conditions for the unique solvability, and for equations with densely defined sectorial operators we obtain necessary and sufficient unique solvability conditions.     

Numerical time schemes for an ocean‐related system of PDEs

In this article we consider a system of equations related to the δ‐primitive equations of the ocean and the atmosphere, linearized around a stratified flow, and we supplement the equations with transparent boundary conditions. We study the stability of different numerical schemes and we show that for each case, letting the vertical viscosity δ go to 0, the stability conditions are the same as the classical CFL conditions for the transport equation. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006     

Second Order Scalar Functional Differential Equations with Piecewise Constant Arguments

The study of functional differential equations with piecewise constant arguments usually results in a study of certain related difference equations. In this paper we consider certain neutral functional differential equations of this type and the associated difference equations. We give conditions under which such equations with almost periodic time dependence will have unique almost periodic solutions, and for certain autonomous cases, we obtain certain stability results and also conditions for chaotic behavior of solutions. We are particularly concerned with such equations which are partially discretized versions of non-forced Duffing equations.     

A Minimax Estimation by Incomplete Data in the Right-Hand Sides of Elliptic Second-Order Partial Differential Equations with Discontinuous Coefficients

We consider systems described by boundary-value problems for elliptic second-order partial differential equations with discontinuous coefficients. These systems arise in the study of steady-state processes of a fluid filtration in multicomponent schistous mediums with nonuniform conditions for a nonideal contact. By observing the state of the systems, we find minimax estimates for functionals of the right-hand sides of these equations. Here we suppose that the right-hand sides of the equations, the boundary conditions, the junction conditions, and the error in the measurements are not known precisely, but we know only the sets to which they belong. We show that finding the minimax estimates is reduced to solving some integro-differential equations.     

Oscillation of solutions of parabolic differential equations of neutral type

In this paper, we investigate a class of parabolic differential equations of neutral type, and obtain some sufficient conditions of the oscillation for such equations satisfying two kinds of boundary value conditions.     

Solvability of a periodic boundary-value problem for systems of functional differential equations with cyclic matrices

We consider first-order systems of linear functional differential equations with regular operators. For families of systems of two equations we obtain the general necessary and sufficient conditions for the unique solvability of a periodic boundary-value problem. For families of systems of n linear functional differential equations with cyclic matrices we obtain effective necessary and sufficient conditions for the unique solvability of a periodic boundary-value problem.     

A parameter estimation scheme for a class of sequential hybrid systems

It may happen that the equations governing the response of dynamical systems have some parameters whose values may not be known a priori and have to be obtained using parameter estimation schemes. In this article, we present a parameter estimation scheme for a class of sequential hybrid systems. By hybrid systems, we refer to those systems whose response is described by different governing equations corresponding to various regimes/modes of operation along with some criteria to switch between the same. In a sequential hybrid system, the different modes are arranged in a specific sequence and the system can switch from a given mode to either the previous mode or the following mode in this sequence. Here, we consider those systems whose governing equations consist of ordinary differential equations and algebraic equations. The conditions for switching between the various modes (referred to as transition conditions) are in the form of linear inequalities involving the system output. We shall first consider the case where the transition conditions are known completely. We present a parameter update scheme along with sufficient conditions that will guarantee bounded parameter estimation errors. Then, we shall consider the case where the transition conditions are not known in the sense that some parameters in these conditions are not known. We present a parameter estimation scheme for this case. We illustrate the performance of the parameter estimation scheme in both cases with some examples.     

An approximate inertial manifolds approach to postprocessing the Galerkin method for the Navier-Stokes equations

In a recent paper we have introduced a postprocessing procedure for the Galerkin method for dissipative evolution partial differential equations with periodic boundary conditions. The postprocessing technique uses approximate inertial manifolds to approximate the high modes (the small scale components) in the exact solutions in terms of the Galerkin approximations, which in this case play the role of the lower modes (large scale components). This procedure can be seen as a defect-correction technique. But contrary to standard procedures, the correction is computed only when the time evolution is completed. Here we extend these results to more realistic boundary conditions. Specifically, we study in detail the two-dimensional Navier-Stokes equations subject to homogeneous (nonslip) Dirichlet boundary conditions. We also discuss other equations, such as reaction-diffusion systems and the Cahn-Hilliard equations.

     

一类非线性偏泛函微分方程的强迫振动性

讨论了一类时滞双曲方程边值问题,给出了该类方程在三类边界条件下解的振动条件.