弱P-调和映射流的紧性性质

分别考虑了映入球面及紧致的齐性Ｒｉｅｍａｎｎｉａｎ空间的弱Ｐ－调和映射流；通过球面及齐性Ｒｉｅｍａｎｎｉａｎ空间的对称性质，证明了弱Ｐ－调和映射流的紧性性质．     

Nonexistence of Blow-up Flows for Symplectic and Lagrangian Mean Curvature Flows

In this paper we mainly study the relation between $|A|^2, |H|^2$ and cosα (α is the Kähler angle) of the blow up flow around the type II singularities of a symplectic mean curvature flow. We also study similar property of an almost calibrated Lagrangian mean curvature flow. We show the nonexistence of type II blow-up flows for a symplectic mean curvature flow satisfying $|A|^2≤λ|H|^2$ and $cosα≥δ>1-\frac{1}{2λ}(½≤α≤ 2)$, or for an almost calibrated Lagrangian mean curvature flow satisfying $|A|^2≤λ|H|^2$ and $cosθ≥δ>max\ {0,1-\frac{1}{λ}}(\frac34≤λ≤ 2)$, where θ is the Lagrangian angle.     

The Blow-up Rate of Positive Solution of a Parabolic System

This paper deals with the blow-up properties of solutions to a system of semilinear heat equations with the boundary conditions u(x,t)=v(x,t)=0 on SR×[0,T).The exact estimates on blow-up rate of solutions are established.     

P-调和映射流的存在性与不唯一性

构造了ｐ 调和发展方程的初边值问题的一个整体弱解；证明了当初值ｕ０（ｘ）是弱ｐ 调和映射但不是弱ｐ 驻调和映射时问题弱解的不唯一性．     

The Second Type Singularities of Symplectic and Lagrangian Mean Curvature Flows

This paper mainly deals with the type II singularities of the mean curvature flow from a symplectic surface or from an almost calibrated Lagrangian surface in a Kähler surface. The relation between the maximum of the Kähler angle and the maximum of |H|² on the limit flow is studied. The authors also show the nonexistence of type II blow-up flow of a symplectic mean curvature flow which is normal flat or of an almost calibrated Lagrangian mean curvature flow which is flat.     

具有Neumann边界条件热方程组的爆破速度

本文考虑具有 Ｎｅｕｍａｎｎ边界条件 ｕ／ｎ＝ｅｖ, ｖ／η＝ｅｕ在 ＳＲ ×（０,Ｔ）热方程组。ｕｔ＝△ｕ,ｖｔ=△ｖ在ＢＲ×（０,Ｔ）解的爆破性质·我们给出了爆破速度估计并证明了爆破仅在边界上发生．     

A New Proof of Hamilton's Theorem on Harmonic Maps from Manifolds with Boundary

We give a simple proof of the well-known Hamilton's result [1] on the heat flows and harmonic maps from manifolds with boundary using the approach of Ding-Lin [2].     

Heat Flows of Subelliptic Harmonic Maps into Riemannian Manifolds with Nonpositive Curvatures

In this paper, we discuss the heat flows of subelliptic harmonic maps into Riemannian manifolds with nonpositive curvatures, and prove the homotopic existence which is a generalization of the Eells–Sampson theorem.     

Blow-up phenomena for a family of Burgers-like equations

By introducing a stress multiplier we derive a family of Burgers-like equations. We investigate the blow-up phenomena of the equations both on the real line R and on the circle S to get a comparison with the Degasperis-Procesi equation. On the line R, we first establish the local well-posedness and the blow-up scenario. Then we use conservation laws of the equations to get the estimate for the L^∞-norm of the strong solutions, by which we prove that the solutions to the equations may blow up in the form of wave breaking for certain initial profiles. Analogous results are provided in the periodic case. Especially, we find differences between the Burgers-like equations and the Degasperis-Procesi equation, see Remark 4.1.     

Blow-up of viscous heat-conducting compressible flows

We show the blow-up of strong solution of viscous heat-conducting flow when the initial density is compactly supported. This is an extension of Z. Xin's result [Z. Xin, Blow up of smooth solutions to the compressible Navier–Stokes equations with compact density, Comm. Pure Appl. Math. 51 (1998) 229–240] to the case of positive heat conduction coefficient but we do not need any information for the time decay of total pressure nor the lower bound of the entropy. We control the lower bound of second moment by total energy and obtain the exact relationship between the size of support of initial density and the existence time. We also provide a sufficient condition for the blow-up in case that the initial density is positive but has a decay at infinity.     

Uniqueness for the Heat Flow for Extrinsic Polyharmonic Maps in the Critical Dimension

We consider the question of uniqueness of weak solutions of the extrinsic polyharmonic map heat flows of arbitrary order in the corresponding critical dimension and show that weak solutions with non-increasing energy are unique. In addition, under a natural regularity assumption on the time-dependence of the energy functional, we prove that the only way for non-uniqueness to occur is by reverse bubbling.     

曲面调和映照的广义Frenet公式及其应用

本文建立了从曲面到复Grassmamn流形调和映照的广义Frenet公式。作为应用，我们得到了调和映照为强共形的一个等价条件。我们也讨论了等距调和映照的曲率pinching性质。从而改进了有关伪全纯曲线的相应结果。     

具有非线性边界条件半线性热方程解的爆破估计(英)

本文考虑具有非线性边界条件-u_x（0，t）=u~q（0，t）在（0，T）半线性热方程u_t-u_(xx)=u~p在（0，∞）×（0，T）的正解．在初值的一些单调性假定下证明了c（T-t）~(-t)≤supu（x，t）≤C（T-0）~(-r)其中r=1／（p-1）如户＞2q-1且r=1／[2（q-1）]如p≤2q-1.     

On the Heat Flow for Harmonic Maps with Potential

Let (M, g) and (N, h) be twoconnected Riemannian manifolds without boundary (M compact,N complete). Let G C (N): ifu: M N is a smooth map, we consider the functional E _G (u) = (1/2) _M [|du|²– 2G(u)]dV _M and we study its associated heat equation. Inthe compact case, we recover a version of the Eells–Sampson theorem,while for noncompact target manifold N, we establishsuitable hypotheses and ensure global existence and convergence atinfinity. In the second part of the paper, we study phenomena of blowingup solutions.     

A Simple Way for Determining the Normalized Potentials for Harmonic Maps

We give a simple way for determining the normalized potentials in the Weierstrass type representation of the harmonic maps for a Riemann surface to a compact symmetric space. As an application, the normalized potential for an arbitrary constant mean curvature surface in space is obtained.     

Blow-up and decay criteria for a model of chemotaxis

For a system of equations introduced by Jäger and Luckhaus (1992) [6] as a model of chemotaxis, the questions of blow-up and global existence criteria are investigated. Specifically, for a convex region, a lower bound for the blow-up time is derived if the solution blows up, and explicit criteria to ensure non-blow-up are determined.     

奇异半线性热方程初值问题解的存在性与Blow-up问题

本文讨论如下奇异半线性热方程的初值问题其中γ＞1，σ＞O，f（x）连续有界非负但不恒为零．我们讨论了问题（1），（2）非负局部经典解的存在性和非负整体解的不存在问题，得到当0＜σ＜1且时，（1），（2）没有非负整体解．当σ＝1且时，（1），（2）没有非负整体解，当σ＞1时（1），（2）没有非负整体解．     

关于一类拟线性抛物方程Blow-up的注记

本文指出了文[1]所给条件的自身矛盾性以及运用凸性方法处理拟线性抛物型方程Blow-up性质的缺陷,同时提出了处理这类问题的较恰当的方法.     

Blow-up profiles for positive solutions of nonlocal dispersal equation

In this paper, we study the blow-up profiles of the nonlocal dispersal equation. More precisely, we prove that the positive solution of nonlocal dispersal equation has different blow-up profiles, depending on the refuge domain.