Multiple positive solutions of nonlinear Neumann problems with time and space singularities

Allowing the nonlinear term to be singular with respect to both the time and space variables, we consider the positive solutions of a nonlinear Neumann boundary value problem. By constructing two height functions and estimating the integrations of these height functions, the existence and multiplicity of positive solutions are established.     

两端固定的奇异梁方程的多重正解

设 n 是一个任意的自然数. 证明了一个两端固定的奇异梁方程的 n 个正解的存在性, 其中非线性项是一个Carathéodory 函数. 主要工具是涉及非线性项的高度函数与锥压缩锥拉伸型的 Krasnoselskii不动点定理. 进一步的研究表明,如果非线性项在零点和无穷远处的增长极限均为无界函数, 该方程仍可能具有正解.     

一类奇异二阶边值问题的正周期解

考察了一类奇异二阶周期边值问题,其中非线性项f(t,u)是局部Caratheódory函数.主要工具是高度函数,它描述了非线性项f(t,u)在有界集合上的增长特性.通过考察高度函数的积分获得了单个或多重正解存在的几个充分条件.我们的工作表明这种存在性与非线性项f(t,u)在u=0附近的性质无关.     

一类次线性分数微分方程的正解存在性

证明了一类非线性项受幂函数控制的次线性分数微分方程的正解存在性.主要方法是锥拉伸与锥压缩型的Krasnosel’skii不动点定理的局部应用.我们的结论表明该方程可以具有一个正解,只要非线性项在某个有界集上的“高度”是适当的.     

POSITIVE SOLUTIONS TO A NONHOMOGENEOUS NONAUTONOMOUS SECONDORDER BOUNDARY VALUE PROBLEM

The existence of multiple positive solutions is studied for a nonlinear nonautonomous second-order boundary value problem with nonhomogeneous boundary conditions. In order to describe the growth behaviors of nonlinearity on some bounded sets, two height functions are introduced. By considering the integrals of the height functions and applying the Krasnosel'skii fixed point theorems on a cone, several new results are proved.     

一类非线性三阶三点边值问题的解和正解

考察了一类含有一阶和二阶导数的非线性三阶三点边值问题的解和正解.通过构造适当的Banach空间并且利用相应的积分方程建立了两个存在定理.主要结论表明,只要非线性项在其定义域的某个子集上的"高度"是适当的,该问题存在一个解或者正解.     

N阶m点非线性边值问题的三正解的特征值准则

应用算子特征值准则研究了一类高阶多点边值问题多重正解的存在性,其中非线性项满足Caratheodory条件.将特征值准则应用到n阶m点的非线性边值问题,并证明了微分方程至少三正解的存在性.     

An existence theorem of a positive solution to a semipositone Sturm–Liouville boundary value problem

We study a positive solution of the semipositone Sturm-Liouville boundary value problem in which the nonlinear term has no numerical lower bound. By considering the integration of certain limit growth functions and applying the Krasnosel’skii fixed point theorem on a cone, an existence theorem is proved, and a classical existence result is extended by this theorem.     

New existence results of positive solution for a class of nonlinear fractional differential equations

In this article, the existence and uniqueness of positive solution for a class of nonlinear fractional differential equations is proved by constructing the upper and lower control functions of the nonlinear term without any monotone requirement. Our main method to the problem is the method of upper and lower solutions and Schauder fixed point theorem. Finally, we give an example to illuminate our results.     

The first Darboux problem for wave equations with nonlinear dissipative term

The first Darboux problem for wave equations with nonlinear dissipative term is considered. The uniqueness, local and global existence and blow-up of solutions of the problem mentioned are investigated. The paper’s originality is the coalescence of two standard methods: a priori estimate of solutions in the class of continuous functions is given by energetic methods; basing on this result a priori estimate in the class of continuously differentiable functions using classical method of characteristics is obtained.     

具有共振的2n阶m点边值问题的可解性

对具有共振的高阶多点边值问题进行研究.首先在具有2n-1阶连续导数的函数全体所成的空间X的子集上定义了指数为0的Fredholm算子L,并在X上定义了投影算子P,使得算子L在其定义域和P的核的交集上是可逆的.然后,在Lebesgue可积函数全体所成的空间Y上定义了投影算子Q,使得L的逆与I-Q及非线性项f的复合是紧算子,其中,I是Y上的恒同算子.最后通过赋予f一定的增长条件,利用Mawhin的重合度理论,证明了具有共振的2n阶m点边值问题至少存在一个解,并给出一个例子验证这一结果.在这里不要求f具有连续性.     

Existence and Multiplicity of Positive Solutions for a Singular Nonlinear High Order Fractional Differential Problem with Multi-point Boundary Conditions

In this paper, a singular nonlinear high order fractional differential problem involving multi-point boundary conditions is solved by means of the fixed point index theory. Some properties of the first eigenvalue corresponding to relevant operator and some new height functions are also used to prove the existence and multiplicity of positive solutions. The nonlinearity depends on arbitrary fractional derivative.     

EXISTENCE OF SOLUTIONS TO A THIRD-ORDER THREE-POINT BOUNDARY VALUE PROBLEM

In this paper,we study the existence of solutions to a third-order three-point boundary value problem.By imposing certain restrictions on the nonlinear term,we prove the existence of at least one solution to the boundary value problem by the method of lower and upper solutions.We are interested in the construction of lower and upper solutions.     

一般Lidstone边值问题的n个正解的存在性

考察了含所有偶数阶导数的一般Lidstone边值问题的正解和对称正解.通过 选择合适的Banach空间和锥,对该问题建立了n个正解或者对称正解的存在性,其 中n是一个任意的自然数.基本工具是等价范数和锥拉伸与锥压缩型的Krasnosel'skii 不动点定理. 结论的主要条件是局部的.换言之,如果非线性项f在某些有界集上的 "高度"是适当的,则该问题可以具有n个正解.     

关于一个非线性三阶三点边值问题的正解存在性

An existence theorem of positive solution is established for a nonlinear third-order three-point boundary value problem. Here, we concentrated on the case that the nonlinear term is neither superlinear nor sublinear, and is not asymptotic at zero and infinity.     

一类二阶非线性奇异边值问题的正解

对非线性项ｆ在ｐｙ’＝ ０奇异但在ｙ＝ ０非奇异的情形下,边值问题 正解的存在性作讨论．     

半正定差分方程正解的存在性

利用锥压缩与锥拉伸不动点定理,在非线性项具有负下界和非减性条件下,讨论了一类二阶半正定非线性差分方程正解的存在性,改进和推广了现有差分方程的一些结果,并将所获得的结果应用于一个具体的二阶半正定非线性差分方程中.     

EXISTENCE OF SOLUTIONS TO 2m-ORDER PERIODIC BOUNDARY VALUE PROBLEM

In this paper, we are concerned with the existence of nontrivial solutions to a 2m-order nonlinear periodic boundary value problem. By the infinite dimensional Morse theory, under some conditions on nonlinear term, we obtain that there exist at least two nontrivial solutions.     

左端固定右端被滑动夹子夹住的非线性弹性梁方程的一个存在定理

通过运用积分方程并考察非线性项的“高度”对一类含有各阶导数的四阶两点边值问题建立了一个解的存在定理.在力学上,这类问题描述了一个左端固定右端被滑动夹子夹住的非线性弹性的形态.     

A discrete fourth-order Lidstone problem with parameters

Various existence, multiplicity, and nonexistence results for nontrivial solutions to a nonlinear discrete fourth-order Lidstone boundary value problem with dependence on two parameters are given, using a symmetric Green’s function approach. An existence result is also given for a related semipositone problem, thus relaxing the usual assumption of nonnegativity on the nonlinear term.