ON THE UPPER ESTIMATES OF FUNDAMENTAL SOLUTIONS OF PARABOLIC EQUATIONS ON RIEMANNIAN MANIFOLDS

ＯＮＴＨＥＵＰＰＥＲＥＳＴＩＭＡＴＥＳＯＦＦＵＮＤＡＭＥＮＴＡＬＳＯＬＵＴＩＯＮＳＯＦＰＡＲＡＢＯＬＩＣＥＱＵＡＴＩＯＮＳＯＮＲＩＥＭＡＮＮＩＡＮＭＡＮＩＦＯＬＤＳ￥ＬＩＪＩＡＹＵ；ＳＨＡＯＸＩＮ（ＤｅｐａｒｔｍｅｌｌｔｏｆＭａｔｈｅｍａｔｉｃｓ，Ａ...     

一类可扩充杆横截挠度方程的Cauchy问题

讨论一类刻划可扩充杆横截挠度的非线性双曲型方程utt+A2u+M(x，‖A1/2 u ‖22)Au=0，这里A=-Δ+I，x∈R\+n，Cauchy问题解的存在唯一性，给出了此 方程有唯一局部解的存在定理.文章所给出的结果的适用性要远大于已有的与此问题相关的结论，对此方程非线性 项的假设要比一般的多.事实上，文章的结果是在打破了以前的所有限制而得到的.      

Existence and Multiplicity of Solutions for a Biharmonic Kirchhoff Equation in $\mathbb{R}^5$

We consider the biharmonic equation $\Delta^2u-\left(a+b\int_{\R^5}|\nabla u|^2dx\right)\Delta u\\+V(x)u=f(u)$, where $V(x)$ and $f(u)$ are continuous functions. By using a perturbation approach and the symmetric mountain pass theorem, the existence and multiplicity of solutions for this equation are obtained, and the power-type case $f(u)=|u|^{p-2}u$ is extended to $p\in(2,10)$, where it was assumed $p\in(4,10)$ in many papers.     

NEUMANN PROBLEM OF ELLIPTIC EQUATIONS WITH LIMIT NONLINIEARITY IN BOUNDARY CONDITION

ＮＥＵＭＡＮＮＰＲＯＢＬＥＭＯＦＥＬＬＩＰＴＩＣＥＱＵＡＴＩＯＮＳＷＩＴＨＬＩＭＩＴＮＯＮＬＩＮＩＥＡＲＩＴＹＩＮＢＯＵＮＤＡＲＹＣＯＮＤＩＴＩＯＮ￥ＤＥＮＧＹＩＮＢＩＮＧ；ＷＡＮＧＸＵＪＩＡ；ＷＵＳＨＡＯＰＩＮＧ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅ...     

p-Laplace型非线性泛函差分方程正解的存在性

作者研究下述的p-Laplace型非线性泛函差分方程边值问题正解和多重正解的存在性,得到相应的充分条件,其中Φp(u)=|u|p-2u,P>1,(?)(0)= 0,C+={(?):(?)∈ C,(?)(k)≥0,k∈[-r,0])．     

Exponential Attractor for Complex Ginzburg-Landau Equation in Three-dimensions

In this paper, we consider the complex Ginzburg-Landau equation (CGL) in three spatial dimensions u_t = ρu + (1 + iϒ )
Δu - (1 + iμ) |u|^{2σ} u, \qquad(1) u(0, x) = u_0(x), \qquad(2) where u is an unknown complex-value function defined in 3+1 dimensional space-time R^{3+1}, Δ is a Laplacian in R³, ρ > 0, ϒ, μ are real parameters. Ω ∈ R³ is a bounded domain. We show that the semigroup S(t) associated with the problem (1), (2) satisfies Lipschitz continuity and the squeezing property for the initial-value problem (1), (2) with the initial-value condition belonging to H²(Ω ), therefore we obtain the existence of exponential attractor.     

Finite time blow-up and global existence of weak solutions for pseudo-parabolic equation with exponential nonlinearity

This paper is concerned with the initial boundary value problem of a class of pseudo-parabolic equation $u_t - \triangle u - \triangle u_t + u = f(u)$ with an exponential nonlinearity. The eigenfunction method and the Galerkin method are used to prove the blow-up, the local existence and the global existence of weak solutions. Moreover, we also obtain other properties of weak solutions by the eigenfunction method.     

Neumann Problem of Quasilinear Elliptic Equations with Limit Nonlinearity in Boundary Condition

This paper is concerned with the existence of solutions to the equation D_j(a^{ij}(x,u)D_i,u)-\frac{1}{2}D_sa^{ij}(x,u)D_iuD_ju + λ u = 0 on a bounded domain under the Neumann boundary condition a{ij}(x,u)D_iuϒ_j = lul^{\frac{2}{n-2}}u.     

On Modified Tricomi Problem of Semi-linear Equation of Mixed Type of Second Kind

In this paper we considered the semi-linear equation of mixed type of second kind, k(x, y)u_{tt} + u_{xx} + a(x, y)u_t + P(x, y)u_t + y(x, y)u - |u|^pu = f(z,y) For the above equation, we solved the modified Tricomi problem and have proved the existence and uniqueness of strong solution in H_1.     

Finite Energy Solutions to the Yamabe Equation

We prove the existence of positive, finite energy solutions to the Yamabe equation

非线性边界条件下二阶奇异差分方程的正解

本文我们考虑如下二阶奇异差分边值问题\begin{equation*}\begin{cases}-\Delta^{2} u(t-1)=\lambda g(t)f(u) ,\ t\in [1,T]_\mathbb{Z},\\u(0)=0,\\ \Delta u(T)+c(u(T+1))u(T+1)=0,\end{cases}\end{equation*}正解的存在性. 其中, $\lambda>0$, $f:(0,\infty)\rightarrow \mathbb{R}$ 是连续的,且允许在~$0$ 处奇异.通过引入一个新的全连续算子, 我们建立正解的存在性.     

R2中非局部椭圆型方程基态解的存在性

本文考虑了一类非局部椭圆型方程-△u+V(x)u=(1/|x|μ*Q(x)F(u)/|x|β)Q(x)f(u)|x|β,x∈R^x,其中V是正的连续位势函数,0<μ<2,0≤β<1/2,2β+μ≤2,F(s)是f(s)的原函数.假设非线性项f(s)满足Trudinger-Moser型次临界指数增长,利用变分方法证明了该方程基态解的存在性.     

含临界指数的类p-Laplacian方程无穷多解的存在性

考虑如下一类含临界指数的类p-Laplacian方程-div(a(|Du|~p)|Du|~(p-2)Du)=:-- |u|~(p~*-2)u+λf(x,u),u∈W_0~(1,p)(Ω),其中Ω∈R~N(N≥2)为有界光滑区域,a:R~+→R为连续函数.由于问题失去紧性,对Palais-Smale序列的分析需要一点技巧.本文利用Lions的集中紧原理,证明了相应泛函I_λ满足(PS)_c条件,再应用Clark临界点定理和亏格的性质,证明了方程无穷多解的存在性.进一步,得到当λ充分小时一个特殊的特征函数的存在性.     

The Poisson equation on complete manifolds with positive spectrum and applications

In this paper we investigate the existence of a solution to the Poisson equation on complete manifolds with positive spectrum and Ricci curvature bounded from below. We show that if a function f has decay f=O(r−1−ε) for some ε>0, where r is the distance function to a fixed point, then the Poisson equation Δu=f has a solution u with at most exponential growth.We apply this result on the Poisson equation to study the existence of harmonic maps between complete manifolds and also existence of Hermitian-Einstein metrics on holomorphic vector bundles over complete manifolds, thus extending some results of Li-Tam and Ni.Assuming moreover that the manifold is simply connected and of Ricci curvature between two negative constants, we can prove that in fact the Poisson equation has a bounded solution and we apply this result to the Ricci flow on complete surfaces.     

Nodal Type Bound States for Nonlinear Schrödinger Equations with Decaying Potentials

In this paper, we are concerned with the existence of nodal type bound state for the following stationary nonlinear Schrödinger equation $$-Δu(x)+V(x)u(x)=|u|^{p-1}u, x∈ R^N, N ≥ 3,$$ where 1 < p < (N+2)/(N-2) and the potential V(x) is a positive radial function and may decay to zero at infinity. Under appropriate assumptions on the decay rate of V(x), Souplet and Zhang [1] proved the above equation has a positive bound state. In this paper, we construct a nodal solution with precisely two nodal domains and prove that the above equation has a nodal type bound state under the same conditions on V(x) as in [1].     

One Case of Appearance of Positive Solutions of Delayed Discrete Equations

When mathematical models describing various processes are analysed, the fact of existence of a positive solution is often among the basic features. In this paper, a general delayed discrete equation

二阶中立型泛函微分方程的周期解

考虑如下一类二阶中立型泛函微分方程的周期解:u″(t)-cu″(t-δ)+a(t)u(t)=λf(t,u(t-τ(t))),其中,λ>0为参数,c和δ为常数.通过应用Krasnoselskii锥不动点定理及一些分析技巧给出了这类方程周期正解的存在性非存在性和多解性.     

（3＋1）维带有源项的反应扩散方程的不变集和精确解

讨论了（3＋1）维带有源项的反应扩散方程ut=A1（u）uxx＋A2（u）uyy＋A3（u）uzz＋B1（u）ux^2;＋B2（u）uy^2＋B3（u）uz^2＋Q（u）．通过构建函数不变集的思想方法．得到了上述方程的几个新精确解．该方法也可以用来解N＋1维反应扩散方程．     

On the Cahn-Hilliard Equation with Nonlinear Principal Part

We study the Calm-Hilliard equation with nonlinear principal part \frac{∂u}{∂t} + D[m(u)(kD^3u - DA(u))] = 0 The existence of classical solutions is established by means of the method based on Campanato spaces and the energy estimates. The corresponding uniqueness is also proved.     

Comparison theory in Lorentzian and Riemannian geometry

A survey is given of selected aspects of comparison theory for Lorentzian and Riemannian manifolds, in which both Jacobi equation and Riccati equation techniques have been employed. Specifically, the existence of conjugate points on a complete geodesic in the presence of positive Ricci curvature and the topic of volume comparison are treated.