渐近线性算子方程的四种类型的解

利用拓扑度理论及不动点指数理论,讨论了渐近线性算子方程的四种类型的解(即零解、正解、负解和变号解)的存在性,并将这一抽象结果应用于微分方程两点边值问题.     

抽象空间中非线性算子方程变号解的存在性研究

利用Banach空间中的锥理论和不动点定理讨论了非线性算子方程变号解的存在性,给出了E_u_0空间下非线性算子方程变号解至少有一个变号解、一个正解和一个负解的条件,并讨论了仅通过一个上解条件得出非线性算子方程变号解的存在性定理.     

2m阶Dirichlet边值问题的多解(英文)

本文讨论了非线性2m阶Dirichlet边值问题多解的存在性.在非线性项满足一定条件时,通过有效地利用锥中的不动点指数理论和解的反对称延拓法,得到关于变号解的一些新的存在结果.确切地说,得到该2m阶边值问题至少存在两个正解,两个负解和多个变号解.     

二阶三点边值问题多解的存在性

利用格结构下的不动点定理,研究了二阶三点边值问题u'(t)+f(t,u(t))=0,0≤t1,u(0)=0,u(1)=ɑu(η)存在多个解,其中至少存在一个正解,一个负解,一个变号解.     

带有两个参数的分数积分边值问题不同类型解的存在性（英文）

本文研究一类积分边界条件中含有两个参数的分数阶微分方程的不同类型解的存在性问题.利用不动点定理及分析方法,给出该积分边值问题存在正解,负解及变号解的参数范围,获得一些新的结论.     

H1（RN）上带限制的椭圆特征问题的三个解

用变分方法证明H~1（R~N）上一个带限制的半线性椭圆特征问题解的存在性.所获得的三个解：一个是正解,一个是负解.对于第三个解,本文只证明了它的存在性,而没有确定它是正解,负解,还是变号解.     

一个带限制的椭圆特征问题的多解和变号解

利用变分方法证明了一个带限制的半线性椭圆特征问题变号解的存在性.所获得的3个解,1个是正解、1个是负解、1个是变号解.在某些附加条件下证明了多重变号解的存在性.     

带有参数的某四阶边值问题解的存在性

延续Yang和Zhang的工作,研究了带有参数的某四阶边值问题非平凡解的存在性．对于此边值问题的非线性项,不改变其在无穷远处的条件,只是改变了在零点处的条件,综合利用临界点理论,收缩性质及流不变集理论,得到了正解、 负解及变号解的存在性．     

序Banach空间超线性算子方程的多重解及其应用

通过不动点指数理论，讨论了一类超线性算子方程的多重解问题。在合适的条件下，我们至少得到了三个解：一个零解，一个正解和一个负解。并将抽象结果应用到超线性微分方程两点边值问题。     

具有p-Laplacian算子的离散混合边值问题的多解性

应用临界点理论研究了具有p-Laplacian算子的离散混合边值问题的多解存在性.进而,当非线性项f≥0时,得到了该边值问题的一个正解.     

Sequential and continuum bifurcations in degenerate elliptic equations

We examine the bifurcations to positive and sign-changing solutions of degenerate elliptic equations. In the problems we study, which do not represent Fredholm operators, we show that there is a critical parameter value at which an infinity of bifurcations occur from the trivial solution. Moreover, a bifurcation occurs at each point in some unbounded interval in parameter space. We apply our results to non-monotone eigenvalue problems, degenerate semi-linear elliptic equations, boundary value differential-algebraic equations and fully non-linear elliptic equations.

     

Existence of solutions for some fourth-order nonlinear elliptic problems

In this paper, we consider the existence of positive, negative and sign-changing solutions for some fourth order semilinear elliptic boundary value problems. We present new results on invariant sets of the gradient flows of the corresponding variational functionals. The structure of the invariant sets will be built into minimax procedures to construct the sign-changing solutions.     

Existence of sign-changing solutions for some asymptotically linear three-point boundary value problems

In this paper, by using the topological degree theory and the fixed point index theory, the existence of three kinds of solutions (i.e., sign-changing solutions, positive solutions and negative solutions) for asymptotically linear three-point boundary value problems is obtained.     

Local and global bifurcation results for a semilinear boundary value problem

We investigate the local and global nature of the bifurcation diagrams which can occur for a semilinear elliptic boundary value problem with Neumann boundary conditions involving sign-changing coefficients. It is shown that closed loops of positive and negative solutions occur naturally for such problems and properties of these loops are investigated.     

Solvability of nonlinear elliptic boundary value problem via its associated linear problem

We investigate the existence of solutions of a nonlinear elliptic boundary value problem at resonance. Under the condition that the associated linear boundary value problem has no sign-changing solution or nontrivial solution and some other additional conditions, we prove the existence of solutions or nontrivial (even multiple) solutions to the nonlinear problem. Thus the existence of solutions can be obtained when the nonlinearity may cross any finite number of eigenvalues of the linear problem.     

Multiple solutions of some fourth-order boundary value problems

For some fourth-order boundary value problems, several new existence theorems on multiple positive, negative and sign-changing solutions are obtained. The critical point theory and the supersolution and subsolution method are employed to discuss this problem.     

Sign-Changing Solutions and Multiple Solutions Theorems for Semilinear Elliptic Boundary Value Problems with a Reaction Term Nonzero at Zero

In this paper, we use the ordinary differential equation theory of Banach spaces and minimax theory, in particular, the local mountain pass lemma to study asymptotically linear and superlinear elliptic boundary value problems with a reaction term nonzero at zero, and get new multiple solutions and sign-changing solutions theorems. Moreover, the sign-changing solutions change sign exactly once under some conditions.