三项混合共轭梯度算法及其收敛性

本文对求解无约束优化问题提出一类三项混合共轭梯度算法,新算法将Hestenes- stiefel算法与Dai-Yuan方法相结合,并在不需给定下降条件的情况下,证明了算法在Wolfe线搜索原则下的收敛性,数值试验亦显示出这种混合共轭梯度算法较之HS和PRP的优势．     

广义Davey-Stewartson方程组的整体解及自相似解

本文研究Dalvey-Stewartson方程组的整体解与自相似解的存在性.首先,运用Ba- nach不动点定理得到一个关于解整体存在性的一般性定理,然后把一类特殊的初始值用到该存在性结果上去从而得到自相似解存在的结论.     

GLOBAL EXISTENCE OF SOLUTIONS FOR A STRONGLY COUPLED REACTION-DIFFUSION SYSTEM

1IntroductionInthispaper,weinvestigatetheglobalexistencealldtllliqllellessofthesmoothsolutiolltotilefollowingIBVPHerefiCR'1isaboulldeddomainwithsllloothboundaryoff,alldal,uZarcunkllowllfullctiolls,QT=(0,T)xfi,ST=(0,T)xoff,Tisanarbitrarypositiveconstallt,R=(--co, co).BI.'Itk=orb(f,x:)% aam(t,x)'(Lk,kistheoutwardnormalderivative,AistheLaplacianoperator,7t(k=(%,....%)(k=1,2)arethegradients.nisanarbitrarypositiveinteger.IBVP(1.1)coillesfi.ommanymathematicalalldphysicalproblelll.Ill11],fo…     

一种解决不等式约束优化问题的光滑牛顿法

本通过引入松弛变量和Fischer函数把带有不等式约束优化问题的K-T条件转化为一个等价的非线性系统，并引入一参数μ，从而提出了一种新的光滑牛顿法。在适当的条件下，证明了算法的全局收敛性，并提供了数值结果。     

求常微分方程周期解的同伦方法

As an important aspect of applications, it is discussed how to find periodic solutions for ordinary differential equations. By using the homotopy method, a global method for finding those solutions is proposed.     

一个新的填充函数

填充函数法是一种解无约束全局极小化问题的方法.这种方法的关键是构造填充函数,在已发表的文献中已经介绍了几种填充函数.在此介绍只含一个参数的填充函数,并且根据此填充函数提出了一种填充函数算法.给出了用这种填充函数法解几个测试问题的计算结果.     

Nonmonotone Trust-Region Method for Nonlinear Programming with General Constraints and Simple Bounds

In this paper, we propose a nonmonotone trust-region algorithm for the solution of optimization problems with general nonlinear equality constraints and simple bounds. Under a constant rank assumption on the gradients of the active constraints, we analyze the global convergence of the proposed algorithm.     

Attractor of dissipative radially symmetric Zakharov equations outside a ball

In this paper the authors study the long time behaviour of the radially symmetric solutions to the damped Zakharov equations on an exterior domain outside a ball and prove the existence of global attractors. Copyright © 2004 John Wiley & Sons, Ltd.     

Growth of graded noetherian rings

We show that every graded locally finite right noetherian algebra has sub-exponential growth. As a consequence, every noetherian algebra with exponential growth has no finite dimensional filtration which leads to a right (or left) noetherian associated graded algebra. We also prove that every connected graded right noetherian algebra with finite global dimension has finite GK-dimension. Using this, we can classify all connected graded noetherian algebras of global dimension two.

     

Non‐linear stability and convection for laminar flows in a porous medium with Brinkman law

The non‐linear stability of plane parallel shear flows in an incompressible homogeneous fluid heated from below and saturating a porous medium is studied by the Lyapunov direct method.In the Oberbeck–Boussinesq–Brinkman (OBB) scheme, if the inertial terms are negligible, as it is widely assumed in literature, we find global non‐linear exponential stability (GNES) independent of the Reynolds number R. However, if these terms are retained, we find a restriction on R (depending on the inertial convective coefficient) both for a homogeneous fluid and a mixture heated and salted from below. In the case of a mixture, when the normalized porosity ε is equal to one, the laminar flows are GNES for small R and for heat Rayleigh numbers less than the critical Rayleigh numbers obtained for the motionless state. Copyright © 2003 John Wiley & Sons, Ltd.