一个带非线性边界条件的强耦合抛物方程组的整体存在性与爆破

本文处理带非线性边界条件 u n=uα, v n=vβ ,(x ,t) ∈ Ω× (0 ,T)的抛物方程组ut =vpΔu ,vt=uqΔv ,(x ,t) ∈Ω× (0 ,T) ,其中Ω RN 为一个有界区域 ,p ,q>0和α ,β≥ 0为常数 .研究了上述问题正解的整体存在性和爆破 ,建立了整体存在和爆破的新标准 .证明了当max{p+β,q+α}≤ 1时正解 (u ,v)整体存在 ,当min{p+β ,q+α}>1且max{α ,β}<1时正解 (u ,v)在有限时刻爆破     

f-Laplace非线性方程的梯度估计和Liouville定理

设(M,g,e~(-f)dv_g)是n维完备光滑的度量测度空间.考虑以下非线性椭圆方程△_f~u+hu~α=0,1α(n+m)/(n+m-2)(n+m≥4)和非线性抛物方程(△_f-?/?t)u+hu~α=0,α0正解的梯度估计.对于经典的Laplace情形,Li (Li J. Gradient estimates and harnack inequalities for nonlinear parabolic and nonlinear elliptic equations on Riemannian manifolds [J]. J Funct Anal,1991, 100:233-256.)证明了正解的梯度估计和Liouville定理.在本文中,对于上述的f-Laplace方程,作者将推导出相应的结果.     

数论问题

(续上期 )例 9　证明 :对任意自然数n ,数 [( 3+5) n]+ 1被 2 n 整除 .这里 [x]表示实数x的整数部分 .证　论证的要点是给予 [( 3+ 5) n]的一个不同的 (但适用的 )表示 .为此 ,我们考虑数α =3+ 5的共轭数 β =3- 5,它们由整系数二次方程x2 - 6x + 4=0相关联 :是该方程的两个根 .记un=αn+ βn.我们现在易于导出 {un}(n≥ 1 )的递推公式 :以αn 乘α2 - 6α + 4=0 ,及 βn 乘 β2 - 6 β+ 4=0 ,并将结果相加 ,即得un + 2 =6un + 1- 4un,n≥ 1 ( 5)因u1=6 ,u2 =2 8都是整数 ,故由 ( 5)及归纳法知所有的un 都是整数 .注意 0 <3- 5<1 .故 0 <β…     

带有Riemann-Liouville分数阶导数的边值问题多正解的存在性(英文)

本文运用Avery-Peterson不动点定理研究以下分数阶边值问题Dα0+Dα0+u=f(t,u,u′,-Dα0+u,-Dα+10+u),t∈[0,1],u(0)=u′(0)=u′(1)=Dα0+u(0)=Dα+10+u(0)=Dα+10+u(1)={0至少三个正解的存在性,其中α∈(2,3]是一实数,Dα0+是α阶Riemann-Liouville分数阶导数.文章最后提供一个具体的例子来说明所得到的结论.     

Quasi-periodic solutions with prescribed frequency in a nonlinear Schrdinger equation

In this paper, one-dimensional (1D) nonlinear Schrdinger equation iut-uxx + Mσ u + f ( | u | 2 )u = 0, t, x ∈ R , subject to periodic boundary conditions is considered, where the nonlinearity f is a real analytic function near u = 0 with f (0) = 0, f (0) = 0, and the Floquet multiplier Mσ is defined as Mσe inx = σne inx , with σn = σ, when n 0, otherwise, σn = 0. It is proved that for each given 0 σ 1, and each given integer b 1, the above equation admits a Whitney smooth family of small-amplitude quasi-periodic solutions with b-dimensional Diophantine frequencies, corresponding to b-dimensional invariant tori of an associated infinite-dimensional Hamiltonian system. Moreover, these b-dimensional Diophantine frequencies are the small dilation of a prescribed Diophantine vector. The proof is based on a partial Birkhoff normal form reduction and an improved KAM method.     

B样条曲面的方向导数与高效求值

1 引言 B样条曲面是几何造型中一种用途广泛的方法,在实际应用中,大量问题需要我们研究曲面的凸性与连续性,它们都归结为求曲面在任意点处关于任意方向的各阶导数的求值问题. 给定(m+M)×(n十N)个空间点f_(ij)及两个非减节点向量{u_i;0≤i≤2m+M}和{v_j;0≤j≤2n+N},则定义在[u_m,u_(m+M)]×[v_n,v_(n+N)]上的m×n次B条曲面为 f(u,v)=(sum from i=0 to m+M-1)(sum from j=0 to n+N-1)(f_(ij)N_i~m(u)N_j~n(v), (1)其中N_i~m(u)和N_j~n(v)为定义在前两节点向量上的规范B样条基函数,它们可以按严格形式递推地定义为下式     

BOUNDEDNESS OF THE HIGHER-DIMENSIONAL QUASILINEAR CHEMOTAXIS SYSTEM WITH GENERALIZED LOGISTIC SOURCE

This article considers the following higher-dimensional quasilinear parabolicparabolic-ODE chemotaxis system with generalized Logistic source and homogeneous Neumann boundary conditions■in a bounded domain??R~n(n≥2) with smooth boundary??, where the diffusion coefficient D(u) and the chemotactic sensitivity function S(u) are supposed to satisfy D(u)≥M1 (u+1)~(-α) and S(u)≤M2(u+1)~β, respectively, where M_1, M_2 0 andα,β∈R. Moreover, the logistic source f (u) is supposed to satisfy f (u)≤a-μu~γ with μ 0,γ≥1, and a≥0. As α+2βγ-1+2γ/n, we show that the solution of the above chemotaxis system with sufficiently smooth nonnegative initial data is uniformly bounded.     

三角代数上Jordan积为幂等元处的高阶ξ-Lie可导映射

设u=Tri(A,M,B)是三角代数,{φn}n∈N:u→u是一列线性映射.本文利用代数分解的方法,证明了如果对任意U,V∈u且U。V=P为标准幂等元,有φn([U,V]ξ)=Σi+j=n(φi(U)φj(V)-ξφi(V)φj(U))(ξ≠±1),则{φn}n∈N是一个高阶导子,其中φ0=id为恒等映射,UoV=UV+VU为Jordan积,[U,V]ξ=UV-ξVU为ξ-Lie积.     

非扩张映象不动点的迭代算法

设C是具有一致Gateaux可微范数的实Banach空间X中的一非空闭凸子集,T是C中不动点集F(T)≠0的一自映象．假设当t→0时,{Xt}强收敛到T的一不动点z,其中xt是C中满足对任给u∈C,xt=tu+(1-t)Txt的唯一确定元．设{αn},{βn}和{γn}是[0,1]中满足下列条件的三个实数列:(i)αn+βn+γn=1;(ii) limn-∞αn=0和．对任意的x0∈C,设序列{xn}定义为xn+1=αnu+βnxn+γnTxn,则{xn}强收敛到T的不动点．     

一类带临界指数增长的椭圆型方程组两个正解的存在性

该文主要讨论带临界指数的椭圆型方程组{-Δu + a(x)u =2α/α+βuα-1vβ + f(x),x ∈Ω,-Δv+b(x)v=2β/α+βuαvβ-1+ g(x),x ∈ Ω,(*)u ＞ 0,v ＞ 0,x ∈Ω,u=v=0,x ∈(a)Ω解的存在性,其中Ω是RN中一个光滑有界区域,N=3,4,a≥2,β≥2...     

Essential self adjointness of laplacians on riemannian manifolds with fractal boundary

We stutly the problem of the essential self-adjointness of Laplacians on Riemannian Manifolds. We show that a sufficient, condition is if the boundary of a manifold M. by which we mean M/M, where M is the metric completion of M, is almost polar set. Two other results concern special cases. when the boundary is some sort of fractal set or even a manifold. It is shown that the boundary is almost polar set in the cases under certain dimensional restrictions.     

关于双曲空间形式的一个注记

本文主要证明一个具有光滑边界的紧黎曼流形,如果有非平凡解,则就等度量同构与双曲空间形式 会的紧区域,这里Ｄ～２■是■的Ｈｅｓｓｉａｎ与ｇ是Ｍ上的黎曼度量． 还证明关于上述方程的边值问题,只有混合边值问题,而且当ｃ＜－１时有解．     

求解二维多区域声波传播问题的一种边界元方法

针对多区域中声波的传播问题,其中每个散射区域的介质是相同的,将散射区域内的声波用一种单双层混合位势的形式来表示,再应用Green定理表示出外部介质区域中的声波,并形成相应的边界积分方程.如果区域个数为M时,传统的边界元方法最终将形成2M个边界积分方程并对应2M个未知函数,而本文的边界元方法最终只形成M个边界积分方程以及对应M个未知函数,从而使得求解的方程和未知数的个数都减少了一倍.最后,通过对数值算例的求解,验证了该方法的可行性及精确性.     

Embeddability of smooth Cauchy-Riemann manifolds

Summary The main purpose of this paper is to give a sufficient condition for global embeddability of smooth Cauchy-Riemann manifolds (CR-manifolds) into complex manifolds with boundary. Namely, let M be a smooth CR-manifold of real dimension 2n – 1 and CR-dimension n – 1, where n 2, which is locally CR-embeddable into a complex manifold. Assume further that the Levi form of M is non-vanishing at each point. The main result of this paper is that such a CR-manifold is globally CR-embeddable into an n-dimensional complex manifold with boundary. Moreover if the Levi form has at each point of M eigenvalues of opposite signs, then M embeds into a complex manifold without boundary.This research is supported by a grant from Consiglio Nazionale delle Ricerche in Italy.     

On(e)-reducible 3-manifolds Which Admit Complete Surface Systems

In the present paper, we consider a class of compact orientable 3-manifolds with one boundary component, and suppose that the manifolds are ?-reducible and admit complete surface systems. One of our main results says that for a compact orientable, irreducible and ?-reducible 3-manifold M with one boundary component F of genus n > 0 which admits a complete surface system S′, if D is a collection of pairwise disjoint compression disks for ?M , then there exists a complete surface system S for M , which is equivalent to S′, such that D is disjoint from S . We also obtain some properties of such 3-manifolds which can be embedded in S3.     

Exponential Contraction in Wasserstein Distances for Diffusion Semigroups with Negative Curvature

Potential Analysis - Let Pt be the (Neumann) diffusion semigroup Pt generated by a weighted Laplacian on a complete connected Riemannian manifold M without boundary or with a convex boundary. It is...     

The Riemannian Manifolds with Boundary and Large Symmetry

Seventy years ago, Myers and Steenrod showed that the isometry group of a Riemannian manifold without boundary has a structure of Lie group. In 2007, Bagaev and Zhukova proved the same result for a Riemannian orbifold. In this paper, the authors first show that the isometry group of a Riemannian manifold M with boundary has dimension at most 1/2 dim M（dim M - 1）. Then such Riemannian manifolds with boundary that their isometry groups attain the preceding maximal dimension are completely classified.     

Aufspaltungen linearer gewöhnlicher Differentialoperatoren und der zugehörigen Greenschen Funktionen

Let M be a regular linear ordinary differential operator of the n-th order, associated with certain homogeneous boundary conditions. Suppose that M is invertable. We provide sufficient conditions to split M into a product of lower order operators M_k, which may be singular at the endpoints of the given interval. To these splittings-which depend on the given boundary conditions-there corresponds a splitting of the associated Green's function. The results are applied in the theory of inverse-positive operators and the theory of totally positive Green's functions. These applications, in general, require the operators M_k to be singular. Moreover, for special classes of operators the splittings can effectively be used for solving boundary value problems numerically.     

带边界Riemann流形上的Sobolev空间等价范数

对具光滑边界αＭ的Ｒｉｅｍａｎｎ流形（Ｍ，ｇ），本文建立了Ｓｏｂｏｌｅｖ空间Ｈ（Ｍ）的等价范数     

Two Dimensional Landau-Lifshitz Equation

In this paper, we consider the Cauchy problem for two dimensional Landau-Lifshitz equation on 2-dimenslonal Riemannian manifold M without boundary. We proved that if u: M × R_+ → S², is a weak solution, then u is unique and smooth on M × R_+ with the exception of finitely many points.