一类非线性积-微分方程极值解的存在性定理

本文讨论非线性积-微分方程初值问题的极值解的存在性。其中利用单调迭代法和上、下解方法,得到了最小解和最大解的存在性定理。     

具有障碍的二阶完全非线性椭圆型弱藕合方程组的粘性解

本文考虑具有障碍的二阶完全非线性椭圆型弱藕合方程组的粘性解．在自然结构条件之下,利用罚技巧,增生算子方法和摄动理论,证明了粘性解的存在性,与Person方法相比,本文的方法的优点在于不依赖于上下解的存在性。最后,给出了粘性解唯一的充分条件．     

带有凹凸非线性项的Klein-Gordon-Maxwell系统解的存在性和多重性

研究一类Klein-Gordon-Maxwell系统解的存在性和多重性.当非线性项是凹凸非线性项时,利用变分方法获得了系统解的存在性和多重性结果,并完善了此系统解的存在性的已有结果.     

一类带有扩散与时滞的流行性传染病模型的行波解

讨论了一类带有扩散与时滞的流行性传染病模型的行波解的存在性.首先,将系统的行波解的存在性问题转化为一个二阶常微分方程组的单调解的存在性问题;应用单调方法和不动点方法,进一步地将问题转化为方程组的上下解的构造问题;应用所建立的引理与定理,通过构造适合的上下解,证明了系统单调行波解的存在性.     

双调和型抛物方程的Schauder估计

该文给出了双调和型抛物方程初值问题解的Schauder估计,并且在适当的空间中证明了解的存在性与惟一性．类似于二阶情形,首先通过Fourier变换得到一个形式解,然后再利用位势理论和逼近方法得到解的正则性、唯一性及存在性．该方法简单而易懂．     

初始可行基的判定

用高等数学的理论和方法,对无初始可行基的线性规划问题解的存在性及求解方法进行研究,得出关于无初始可行基的线性规划问题解的存在性的六个定理,回答了无初始可行基的线性规划问题解的存在条件和该问题的初始可行基的确定方法.     

奇异半线性椭圆问题解的存在与不存在性(英文)

本文研究了奇异半线性椭圆问题.利用上下解方法,获得了该问题解的一个存在性和不存在性结果.     

一类非线性积－微分方程极值解的存在性定理

本文讨论非线性积－微分方程初值问题的极值解的存在性．其中“利用单调迭代法和上、下解方法，得到了最小解和最大解的存在性定理．     

一阶混合型脉冲微分方程的周期边值问题

通过建立新的比较定理,利用上下解方法,单调迭代方法和不动点定理证明了一阶非线性混合型脉冲微分方程的周期边值问题的可解性及极值解的存在性。     

一类非线性控制系统解的渐近性质

主要目的是研究一类非线性控制系统解的渐近性质。通过建立沿着解的无穷积分和借助于积分形式的LaSalle不变原理,得到了关于系统解的二分性和全局渐近性的判别准则。改进和进一步发展了Айсагалиев所得到的研究方法与结论。     

二阶时滞微分方程边值问题的上下解方法

主要利用上下解方法和Schauder不动点定理,研究一类二阶时滞微分方程边值问题的正解存在性.为了验证结论的正确性,本文在结尾部分给出了两个例子.     

Positive solutions of singular Emden–Fowler boundary value problem with negative exponent and multiple impulses

In this paper, we first give the method of lower and upper solutions for the existence of positive solutions to a singular impulsive boundary value problem. Then we obtain a necessary and sufficient condition for the existence of positive solutions of Emden–Fowler singular impulsive boundary value problem by means of the method of lower and upper solutions.     

Monotone iterative method for the second-order three-point boundary value problem with upper and lower solutions in the reversed order

This article introduces a new concept of upper and lower solutions and studies the existence and uniqueness of solutions of second-order three-point boundary value problems with upper and lower solutions in the reversed order. The sufficient conditions for the existence and uniqueness of solutions are obtained by using the monotone iterative method, meantime, the iterative sequence for solving a solution and its error estimate formula under the condition of unique solution are given. Some results of previous literature are extended and improved. A numerical example is also included to illustrate the effectiveness of the proposed results.     

Traveling wave solutions in delayed nonlocal diffusion systems with mixed monotonicity

This paper deals with the existence of traveling wave solutions in delayed nonlocal diffusion systems with mixed monotonicity. Based on two different mixed-quasimonotonicity reaction terms, we propose new definitions of upper and lower solutions. By using Schauder's fixed point theorem and a new cross-iteration scheme, we reduce the existence of traveling wave solutions to the existence of a pair of upper and lower solutions. The general results obtained have been applied to type-K monotone and type-K competitive nonlocal diffusive Lotka-Volterra systems.     

ALMOST PERIODIC SOLUTIONS TO SOME NONLINEAR DELAY DIFFERENTIAL EQUATION

The existence of an almost periodic solutions to a nonlinear delay diffierential equation is considered in this paper. A set of sufficient conditions for the existence and uniqueness of almost periodic solutions to some delay diffierential equations is obtained.     

负指数Emden Fowler方程奇异边值问题的正解

本文利用上下解方法和不动点理论给出了负指数Ｅｍｄｅｎ Ｆｏｗｌｅｒ方程奇异边值问题有Ｃ［０，１］和Ｃ１［０，１］正解存在的充分必要条件．     

一类奇异次线性边值问题正解存在的充分必要条件

本文研究一类奇异次线性边值问题正解的存在性，得到Ｃ［０，１］正解和Ｃ１［０，１］正解存在的充分必要条件，也得到正解的唯一性．     

一类四阶次线性奇异边值问题的正解

本文利用极大值原理和通过构造上下解给出了一类四阶次线性微分方程的奇异边值问题有C2[0,1]和C3[0,1]正解存在的充分必要条件.     

负指数EmdenFowler方程奇异边值问题的正解

本文利用上下解方法和不动点理论给出了负指数ＥｍｄｅｎＦｏｗｌｅｒ方程奇异边值问题有Ｃ［０，１］和Ｃ１［０，１］正解存在的充分必要条件．     

Existence and nonexistence results for a singular boundary value problem arising in the theory of epitaxial growth

The existence of stationary radial solutions to a partial differential equation arising in the theory of epitaxial growth is studied. It turns out that the existence or not of such solutions depends on the size of a parameter that plays the role of the velocity at which mass is introduced into the system. For small values of this parameter, we prove the existence of solutions to this boundary value problem. For large values of the same parameter, we prove the nonexistence of solutions. We also provide rigorous bounds for the values of this parameter, which separate existence from nonexistence. The proofs come as a combination of several differential inequalities and the method of upper and lower functions applied to an associated two‐point boundary value problem. Copyright © 2013 John Wiley & Sons, Ltd.