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1.
The author reviews briefly some of the recent results on the blow-up problem for the incompressible Euler equations on R^N and also presents Liouville type theorems for the incompressible and compressible fluid equations.  相似文献   

2.
The multiplicity and bifurcation of a two-point boundary value problem(BVP) of nonlinear differential equations(NLDE) are studied firstly using a manifold method.And by some convenient numerical approaches,the discussion on the solutions to the BVP of two order NLDE is turned into the problem on the intersections of the end manifold with the target manifold defined by the boundary conditions,also the bifurcation diagrams and the numerical solutions to the NLDE are obtained.As an example,a mathematical model describing the deformations of elastic circular bar used as gripper and spring element is discussed.  相似文献   

3.
李兴校  曹林芬 《数学季刊》2007,22(3):344-351
The paper studies a class of nonlinear elliptic partial differential equations on a compact Riemannian manifold (M,g) with some curvature restriction.The authors try to prove some uniqueness and nonexistent results for the positive solutions of the equations concerned.  相似文献   

4.
The author obtains sharp gradient estimates for the heat kernels in two kinds of higher dimensional Heisenberg groups -- the non-isotropic Heisenberg group and the Heisenberg type group Hn,m. The method used here relies on the positive property of the Bakry-Emery curvature F2 on the radial functions and some associated semigroup technics.  相似文献   

5.
In this paper, the author considers the Cauchy problem for semilinear wave equations with critical exponent in n≥4 space dimensions. Under some positivity conditions on the initial data, it is proved that there can be no global solutions no matter how small the initial data are.  相似文献   

6.
The existence of C~∞ -solutions to Dirichlet problem for Monge-Ampere equation degenerate on boundary is proved, and some applications to the equation prescribed Gaussian curvature are also given.  相似文献   

7.
The author introduces the w-function defined on the considered spacelike graph M.Under the growth conditions w = o(log z) and w = o(r),two Bernstein type theorems for M in Rmn+ mare got,where z and r are the pseudo-Euclidean distance and the distance function on M to some fixed point respectively.As the ambient space is a curved pseudoRiemannian product of two Riemannian manifolds(Σ1,g1) and(Σ2,g2) of dimensions n and m,a Bernstein type result for n = 2 under some curvature conditions on Σ1 and Σ2 and the growth condition w = o(r) is also got.As more general cases,under some curvature conditions on the ambient space and the growth condition w = o(r) or w = o(√r),the author concludes that if M has parallel mean curvature,then M is maximal.  相似文献   

8.
The viscosily splitting method for the Navier-Stokes equations on two dimensional multi-connected domains is considered. The equation is split into an Euler equation and a non-stationary Stekes equation within each time step. The author proves the convergence theorem as he has done for the problem on simply connected domains, and the rate of convergence is improved from loss than 1/4 to 1.  相似文献   

9.
The first part of this article is an overview on some recent major developments in the field of analysis and partial different equations.It is a brief presentation given by the author at a round table discussion.The second part is a supplement of various details provided by several outstanding researchers on subjects.  相似文献   

10.
The author considers the hyperbolic geometric flow δ2/δt2 g(t) =-2Ricg(t) introduced by Kong and Liu. Using the techniques and ideas to deal with the evolution equations along the Ricci flow by Brendle, the author derives the global forms of evolution equations for Levi-Civita connection and curvature tensors under the hyperbolic geometric flow. In addition, similarly to the Ricci flow case, it is shown that any solution to the hyperbolic geometric flow that develops a singularity in finite time has unbounded Ricci curvature.  相似文献   

11.
SCALAR CURVATURES ON NONCOMPACT RIEMANN MANIFOLDS   总被引:1,自引:1,他引:0  
SCALARCURVATURESONNONCOMPACTRIEMANNMANIFOLDS¥ZHOUDETANGAbstract:Theauthorobtainssometheoremsforafunctiontobethescalarcurvatur...  相似文献   

12.
张金良 《大学数学》2005,21(4):115-119
以[2]中经典微分几何问题为切入点,运用复数与三角工具广泛深入地探讨了“过曲面上一点有n条切线,若相邻两条切线的交角为2nπ,曲面法线与切线所定平面截得曲线的曲率半径为ρ1,ρ2,ρ3,…,ρn时,∑ni=11ρim,∑ni=1ρi,∏ni=1ρi的结果”,得到了法曲率与相关的三个有趣定理.  相似文献   

13.
In this paper we characterize sprays that are metrizable by Finsler functions of constant flag curvature. By solving a particular case of the Finsler metrizability problem, we provide the necessary and sufficient conditions that can be used to decide whether or not a given homogeneous system of second order ordinary differential equations represents the geodesic equations of a Finsler function of constant flag curvature. The conditions we provide are tensorial equations on the Jacobi endomorphism. We identify the class of homogeneous SODE where the Finsler metrizability is equivalent with the metrizability by a Finsler function of constant flag curvature.  相似文献   

14.
CONFORMALDEFORMATIONOFCOMPLETESURFACEWITHNEGATIVECURVATUREZHOUDETANGManuscriptreceivedOctober31,1994.RevisedAugust30,1995.D...  相似文献   

15.
首先叙述双曲空间中曲面的Gauss映照的定义;导出Gauss映照所满足的Beltrami方程;给出了给定平均曲率曲面的Weierstrass表示公式;并讨论了这种表示的完全可积条件.  相似文献   

16.
In this paper we consider Hamilton's Ricci flow on a 3-manifold with a metric of positive scalar curvature. We establish several a priori estimates for the Ricci flow which we believe are important in understanding possible singularities of the Ricci flow. For Ricci flow with initial metric of positive scalar curvature, we obtain a sharp estimate on the norm of the Ricci curvature in terms of the scalar curvature (which is not trivial even if the initial metric has non-negative Ricci curvature, a fact which is essential in Hamilton's estimates [R.S. Hamilton, Three-manifolds with positive Ricci curvature, J. Differential Geom. 17 (1982) 255-306]), some L2-estimates for the gradients of the Ricci curvature, and finally the Harnack type estimates for the Ricci curvature. These results are established through careful (and rather complicated and lengthy) computations, integration by parts and the maximum principles for parabolic equations.  相似文献   

17.
Finsler空间上的Weyl曲率   总被引:1,自引:0,他引:1  
The Weyl curvature of a Finsler metric is investigated. This curvature constructed from Riemannain curvature. It is an important projective invariant of Finsler metrics. The author gives the necessary conditions on Weyl curvature for a Finsler metric to be Randers metric and presents examples of Randers metrics with non-scalar curvature. A global rigidity theorem for compact Finsler manifolds satisfying such conditions is proved. It is showed that for such a Finsler manifold,if Ricci scalar is negative,then Finsler metric is of Randers type.  相似文献   

18.
The author studies the properties and applications of quasi-Killing spinors and quasi-twistor spinors and obtains some vanishing theorems. In particular, the author classifies all the types of quasi-twistor spinors on closed Riemannian spin manifolds. As a consequence, it is known that on a locally decomposable closed spin manifold with nonzero Ricci curvature, the space of twistor spinors is trivial. Some integrability condition for twistor spinors is also obtained.  相似文献   

19.
20.
This note describes an observation connecting Riemannian manifolds of constant sectional curvature with a particular class of Lie superalgebras. Specifically, it is shown that the structural equations of a space M with constant sectional curvature, of one variety or another, nearly coincide with some identities satisfied by tensors which can be used to construct some specific families of Lie superalgebras. In particular, one obtains either osp(n,2), spl(n,2), or osp(4,2n) if the Riemannian manifold has constant curvature, constant holomorphic curvature or constant quaternion-holomorphic curvature, respectively.Mathematics Subject Classiffications (2000). 17A70, 53C29, 53C99, 57Rxx  相似文献   

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