关于Hammerstein型非线性积分方程固有值的一点注记

Let Aφ(x)=∫_GK(x,y)f(y,φ(y))dy, where G is a bounded closed domain in Euclidean space, K(x,y) is continuous on G×G, f(x,u) is continuous on G×R, and f(x,0)≡0. Set G_x={x|x∈G,K(x,y)≠0},G_y={y|y∈G,K(x,y)≠0},G₁=G_x∩G_y≠φ.Let K₁(x,y) be the restriction of K(x,y) on G₁×G₁,f₁(x,u)be the restriction of f(x, u) on G₁× R, and A₁φ=∫_G1K₁(x,y)f₁(y,φ₁(y))dy, The main result of this paper is Theorem λ≠0 is an eigenvalue of A, if and only if λ is an eigenvalue of A₁.     

超线性可变号核Hammerstein型积分方程的固有值

In this paper we use the theory .of topological degree to investigate the eigenvalues of Hammerstein superlinear integral equations with variable sign kernel:Aφ(x)=∫_GK(x,y)f(y,φ(y))dy=λφ(x). We have proved that except at most a sequence of numbers {λ_n}, which converges to zoro, all other numbers λ are eigenvalues of A.     

关于赋权图中重圈的一个范型定理

设G=(V, E; w)为赋权图,定义G中点v的权度d_G^w(v)为G中与v相关联的所有边的权和.该文证明了下述定理: 假设G为满足下列条件的2 -连通赋权图: (i) 对G中任何导出路xyz都有w(xy)=w(yz); (ii)对G中每一个与K_1,3或K_1,3+e同构的导出子图T, T中所有边的权都相等并且min{max{d_G^w(x), d^w_G(y)}:d(x,y)=2,x,y∈ V(T)}≥ c/2. 那么, G中存在哈密尔顿圈或者存在权和至少为 c 的圈. 该结论分别推广了Fan^[5], Bedrossian等人^[2]和Zhang等人^[7]的相关定理     

Hammerstein型积分方程组的非零解及其对两点边值问题的应用

本文研究Hammerstein型积分方程组 (Ⅰ)φ(x)=∫_G K_1(x,y)f_1(φ(y),ψ(y))dy, ψ(x)=∫_G K_2(x,y)f_2(φ(y),ψ(y))dy非零解的存在性(其中G为R~N中有界闭区域,mesG=1,并将所得结果应用于二阶常微分方程两点边值问题 (Ⅱ)(t)=-f(x(t),(t)), α_0x(0)-β_0(0)=0, α_1x(1) β_1(1)=0。其中α_0、α_1、β_0、β_1≥0,|α_0 β_0 -α_1 α_1 β_1|≠0。所得结论与[1]第四章及[3]第六章所述结论具有不同形式,且不能用[1、3]的方法得出,特别当f(u,v)是多项式情况下所得结果是[2]中部分结果的推广和补充。     

Symmetry and regularity of solutions to a system with three-component integral equations

Consider the system with three-component integral equations u(x) = Rn |x y|α nw(y)rv(y)q dy,v(x) = Rn |x y|α nu(y)pw(y)rdy,w(x) = Rn |x y|α nv(y)q u(y)pdy,where 0 < α < n,n is a positive constant,p,q and r satisfy some suitable conditions.It is shown that every positive regular solution(u(x),v(x),w(x)) is radially symmetric and monotonic about some point by developing the moving plane method in an integral form.In addition,the regularity of the solutions is also proved by the contraction mapping principle.The conformal invariant property of the system is also investigated.     

广义Hardy算子的加权Φ—不等式

In this paper,the conditions on pairs of weights(u,v)are given such that for the generalized Hardy operator Tf(x)=∫0^∞K（x,y)f(y)dy the following Φ-inequality holds:Φ2^-1(∫0^∞Φ2（Tf(x))V(x)dx≤CΦ1^-1(∫0^∞Φ1(f(x))U(x)dx)，where Φ1,Φ2 are Young function;the corresponding weak type Φ-inequality for T is characterized.     

一类非线性混合型方程的Tricomi问题

本文考虑非线性混合型方程 k(x,y)u_xx+u_yy+α(x,y)u_x+β(x,y)u_y+γ(x,y)u-|u|^ρu=f(x,y)的Tricomi 问题.利用能量积分和不动点原理,在很弱的条件下证明了H¹强解的存在性.     

具投放的中立型时滞竞争扩散系统正周期解的存在性

利用Nussbaum 度理论建立了具投放的中立型时滞竞争扩散系统 x′₁(t)=x₁(t)[a₁(t)-b₁(t)x₁(t)-c₁(t)y(t) ]+D₁(t)[x₂(t)-x₁(t)]+S₁(t), x′₂(t)=x₂(t)[a₂(t)-b₂(t)x₂(t)]+D₂(t)[x₁(t)-x₂(t) ]+S₂(t), y′(t)=y(t)[a₃(t)-b₃(t)y(t)-α(t)y(t-τ₁(t))-β(t) ∫⁰_τ k(s)y(t+s)ds -γ(t)y’(t-τ₂(t))-c₃(t)x₁(t)]. 存在正周期解的一个充分条件.     

Hammerstein型非线性积分方程的固有值与固有函数

<正> 本文是作者工作[1]—[3]的继续.利用 Leray-Schauder 拓扑度理论研究下面形式的Hammerstein 型非线性积分方程(?)(x)=integral G k(x,y)f[(?)(y)]dy=A(?)(x) (1)的固有值与固有函数,这里 G 表 N 维欧氏空间 R~N 中某有界闭域,函数 f(u) 在0≤u≤δ(δ>0)上连续且 f(0)=0.以下,恒用 f′+(0)表 f(u)在点 u=0的右导数.定理1 假定:(i)非负连续核 k(x,y) 满足k(x,x)(?)0 (x∈G);     

拟线性退化抛物型方程组解的整体存在性和爆破

该文研究光滑有界区域Ω( R^N (N≥ 1) 上具有齐次Dirichlet边界条件的拟线性退化抛物型方程组 u_t-div(|▽u|^p-2 ▽u) =av^α, v_t-div(|▽v|^q-2 ▽v) =bu^β 的非负解的性质, 其中p, q>2, α, β ≥ 1, a, b> 0是常数. 该文指出上述方程组的解是否在有限时刻爆破依赖于初值、系数 a 与 b以及 αβ 和 (p-1)(q-1)之间的关系.     

Multibump solutions for discrete periodic nonlinear Schrödinger equations

In this paper, we study the existence of multibump solutions for discrete nonlinear Schrödinger equations with periodic potentials. We first reduce the existence of multibump homoclinic solutions to the existence of an isolated homoclinic solution with a nontrivial critical group. Then, we study the existence of homoclinics with nontrivial critical groups for both superlinear and asymptotically linear discrete periodic nonlinear Schrödinger equations, and we provide simple sufficient conditions for the existence of homoclinics with nontrivial critical groups in the positive definite case. As an application, we get, without any symmetry assumptions, infinitely many geometrically distinct homoclinic solutions with exponential decay at infinity.     

含临界指数p-Kirchhoff型方程的非平凡解

本文研究了一类含临界指数的p-Kirchhoff型方程.利用变分方法与集中紧性原理,通过证明对应的能量泛函满足局部的(PS)_c条件,得到了这类方程非平凡解的存在性,推广了关于Kirchhoff型方程的相关结果.     

Gap solitons in periodic discrete nonlinear Schrödinger equations with saturable nonlinearities

The main result of the paper concerns the existence of nontrivial exponentially decaying solutions to periodic stationary discrete nonlinear Schrödinger equations with saturable nonlinearities, provided that zero belongs to a spectral gap of the linear part. The proof is based on the critical point theory in combination with periodic approximations of solutions. As a preliminary step, we prove also the existence of nontrivial periodic solutions with arbitrarily large periods.     

一个带Hardy项的椭圆方程的多重解

通过对偶变分方法证明了一个带Hardy项和临界非线性的非线性椭圆方程的非平凡解的存在性和多重性.     

Periodic Nonlinear Schrödinger Equation with Application to Photonic Crystals

We present some results on existence of nontrivial solutions of periodic stationary nonlinear Schr?dinger equations. We also sketch an application to nonlinear optics and discuss some open problems. Received: December 2004     

Banach空间中超线性Hammerstein型积分方程的解及其应用

本文利用不动点指数理论研究Ｂａｎａｃｈ空间中超线性Ｈａｍｍｅｒｓｔｅｉｎ型积分方程正解及非零解的存在性，并应用于Ｂａｎａｃｈ空间中超线性常微分方程的Ｓｔｕｒｍ－Ｌｉｏｕｖｉｌｌｅ问题，最后，本文给出了一个非线性常微分方程无穷组存在正解的例子．     

The existence of periodic solutions of nonlinear wave equations on Sn

We are concerned with the existence of time periodic solutions of nonlinear wave equations on n-dimensional spheres. The existence of nontrivial periodic solution in case 0 is a solution is proved. the existence of multiple, especially infinitely many, time periodic solutions is established for several classes f nonlinear terms which satisfy some symmetry properties such as time translation invariance or oddness. Furhermore, this paper also studies the effect of perturbations which are not small and which destroy the symmetry, and shows how multiple solutions persist despite the nonsymmetric perturbations if the growth of nonlinear term at infinity is suitable controlled.     

Existence of entire positive solutions for a critical system of nonlinear elliptic equations

In this paper, using the fibering method introduced by Pohozaev, we establish an existence of multiple nontrivial positive solutions for a system of nonlinear elliptic equations in R^N with lack of compactness studying the properties of Palais-Smale sequence of the energy functional associated with the system.     

Positive periodic solutions of parabolic evolution problems: a translation along trajectories approach

A translation along trajectories approach together with averaging procedure and topological degree are used to derive effective criteria for existence of periodic solutions for nonautonomous evolution equations with periodic perturbations. It is shown that a topologically nontrivial zero of the averaged right hand side is a source of periodic solutions for the equations with increased frequencies. Our setting involves equations on closed convex cones, therefore it enables us to study positive solutions of nonlinear parabolic partial differential equations.     

Existence of nontrivial periodic solutions for first order functional differential equations

In this paper, in the case of not requiring the nonlinear terms to be non-negative the existence of nontrivial periodic solutions for the first order functional differential equations is considered by using the partial ordering theory.