The Formual of Generalized Center－Weak Saddle

In his paper,a problem of center-weak focus of a general system of degree n is transformed into a problem of generalized center-weak saddle.It offers:(1) the calculating formula of the saddle values of the former 4 orders in the general system of degree three;(2) some calculating formulae of the saddle values in the general homogeneous system of degree n. The problem of center-focus(saddle)plays an important role in the qualitative theory of ordinary differential equations.However,since the calculations are difficult,the results have not been satisfactory.On the basis of the author‘s work,Northeast.Math.J.,13(4)(1997),487-494,the paper offers some calculating formulae of the saddle values.     

The Generalized Center-Weak Saddle of General Homogeneous System of Degree n

In this paper,a problem of center-weak focus of a homogeneous system of degree n is transformed into a problem of generalized center-weak saddle. It provides formulae for the saddle values of the first (4-(-1)n)m orders in such a system,where m=n-1 if n is an even number and m=(n-1)/2 if n is an odd number.     

PERIODIC TRAVELLING-WAVE SOLUTION OF BRUSSELATOR

The Hopf bifurcation Theorem requires that one at first knows all eigenvalues of the linearized system;and a diffieulty in applying the Hopf Theorem is that in the general case we are unable to solve an algebraic equation of degree n (n≥3) with parameter coefficients.This paper firstly proves Theorem 1 which enables us to know the existence of the Hopf bifuecation by direct use of the coefficients of the characteristic equ ation of the linearized system for the case where the characteristic equation of the linearized system has degree 2,3 or 4.Then by using Theorem 1,we gave out the condition for existing a periodic traveling-wave solution of Brusselator in diffusion by Hopf bifurcat on.Finally,we discuss the problem of bifurcation direction and the problem of stability of the bifurcation.     

Periodicity and Stability in Periodic <Emphasis Type="Italic">n</Emphasis>-Species Lotka-Volterra Competition System with Feedback Controls and Deviating Arguments

By using the method of coincidence degree and Lyapunov functional, a set of easily applicable criteria are established for the global existence and global asymptotic stability of strictly positive(componentwise)periodic solution of a periodic n-species Lotka-Volterra competition system with feedback controls and several deviating arguments.The problem considered in this paper is in many aspects more general and incorporate as special cases various problems which have been studied extensively in the literature.Moreover,our new criteria,which improve and generalize some well known results, can be easily checked.     

BLOW-UP CONDITIONS FOR A SEMILINEAR PARABOLIC SYSTEM ON LOCALLY FINITE GRAPHS

In this paper,we investigate a blow-up phenomenon for a semilinear parabolic system on locally finite graphs.Under some appropriate assumptions on the curvature condition CDE’(n,0),the polynomial volume growth of degree m,the initial values,and the exponents in absorption terms,we prove that every non-negative solution of the semilinear parabolic system blows up in a finite time.Our current work extends the results achieved by Lin and Wu(Calc Var Partial Differ Equ,2017,56:Art 102) and Wu(Rev R ...     

ON THE STRUCTURE OF INTEGRAL SURFACES NEAR A HIGHER ORDER FOCUS AND SADDLE

In this paper the structure of integral surfaces near a higher order focus and saddle,of ordinary differential equations in complex domain is studied by reducing to the normal form system.The formulae of the normal form system are also given.     

SADDLE VALUES AND INTEGRABILITY CONDITIONS OF QUADRATIC DIFFERENTIAL SYSTEMS

In the first section of the paper,the first three saddle values R_1,R_2,R_3 of the realquadratic differential system(QDE) are computed by use of the method with which Poincaréresearchs on Hopf bifurcation.In the second section,by applying the method and results ofDulac seeking integrability conditions of QDE it is proved that the system is integrable ifand only if R_1=R_2=R_3=0,and it is also true when the system is complex.The integrabilityconditions given here can be applied much more easily then Dulac's.In the last part ofthe paper,it is pointed out that iR_1,iR_2,iR_3 are the first three focal values of the weakfocus of the complex system.By the formulae of R_1,R_2,R_3 and the result in section 2,one can easily give the formulae of the focal values for the real QDE with Bautin formand give a new proof of Bautin's famous result.     

THE EXISTENCE AND STABILITY OF STATIONARY SOLUTIONS OF THE INFLOW PROBLEM FOR FULL COMPRESSIBLE NAVIER-STOKES-POISSON SYSTEM

In this paper,we consider an inflow problem for the non-isentropic Navier-StokesPoisson system in a half line(0,∞).For the general gas including ideal polytropic gas,we first give some results for the existence of the stationary solution with the aid of center manifold theory on a 4×4 system of autonomous ordinary differential equations.We also show the time asymptotic stability of the stationary solutions with small strength under smallness assumptions on the initial perturbations by using an elementary energy method.     

求解非线性规划的原始对偶内点法(英文)

In this paper, we propose a primal-dual interior point method for solving general constrained nonlinear programming problems. To avoid the situation that the algorithm we use may converge to a saddle point or a local maximum, we utilize a merit function to guide the iterates toward a local minimum. Especially, we add the parameter ε to the Newton system when calculating the decrease directions. The global convergence is achieved by the decrease of a merit function. Furthermore, the numerical results confirm that the algorithm can solve this kind of problems in an efficient way.     

ANTI-SYMMETRIC SYSTEM OF SECOND ORDER EVOLUTION EQUATIONS

Under some conditios to find the interaction, of waves is, in the final analysis, to solve kind of anti-symmetric system of second order evolution equations. Thus, in §2 of this paper we discuss the Cauchy problem of anti-symmetric system of second order evolution equations under general situation. It is found that if there is a solution of the system of linear equations corresponding to the anti-symmetric system of second order evolution equations, then for the Cauchy problem there exists a uniqe solution In §3, the abstract boundary value problem of anti-symmetric system of second order evolution equations is studied In §4 we give an example to illuminate the Solvability of initial-boundary value problem about anti-symmetric system of second order evolution equations In the physcial sense, this example is none other then the interaction problem of waves     

求解“余数问题”的算法研究

求解"余数问题"可归结为一次同余式组x≡ri(mod pi)或一次不定方程组x=pixi+ri的求解.当方程的个数n与模pi(i=1,2,…,n)较大时,用同余式理论和孙子定理求解的过程非常繁琐.为此,运用试算分析法和辗转相除法,给出了求解上述问题的两种通用的计算机算法和程序.通过实践证明,该算法具有计算步骤简便,求解灵活快速,通用性强等优点.     

计量逻辑学中的雪崩逻辑公式

将密码学中满足严格雪崩准则的布尔函数的概念引入到计量逻辑学之中,提出了雪崩逻辑公式的概念,并研究了雪崩逻辑公式的真度及其性质。证明了至少含有三个原子公式的雪崩逻辑公式的真度之集为H1={k/2n-12n-3≤k≤3×2n-3;n=3,4,…},在此基础上,通过引入函数ξ建立了n(n≥3)元雪崩布尔函数个数的表达式,给出了雪崩逻辑公式的构造方法。最后,研究了反射变换下k阶雪崩逻辑公式的性质。     

Evaluation of ST preconditioners for saddle point problems

The general block ST decomposition of the saddle point problem is used as a preconditioner to transform the saddle point problem into an equivalent symmetric and positive definite system. Such a decomposition is called a block ST preconditioner. Two general block ST preconditioners are proposed for saddle point problems with symmetric and positive definite (1,1)-block. Some estimations of the condition number of the preconditioned system are given. The same study is done for singular (1,1)-block.     

Limit Cycle Bifurcations Of A Kind Of Lienard System With A Hypobolic Saddle And A Nilpotent Cusp

This paper gives a general theorem on the number of limit cycles of a near Hamiltonian system with a heteroclinic loop passing through a hyperbolic saddle and a nilpotent cusp. Then we study a kind of Lienard systems of type (n,4) for 3&lt;=n&lt;=27 and obtain the lower bound of the maximal number of limit cycles for this kind of system.     

广义鞍点问题的块三角预条件子

本文对Golub和Yuan(2002)中给出的ST分解推广到广义鞍点问题上,给出了三种块预条件子,并重点分析了其中两种预条件子应用到广义鞍点问题上所得到的对称正定阵,得出了其一般的性质并重点研究了预处理矩阵条件数的上界,最后给出了数值算例.     

Global saddle points of nonlinear augmented Lagrangian functions

We notice that the results for the existence of global (local) saddle points of augmented Lagrangian functions in the literature were only sufficient conditions of some special types of augmented Lagrangian. In this paper, we introduce a general class of nonlinear augmented Lagrangian functions for constrained optimization problem. In two different cases, we present sufficient and necessary conditions for the existence of global saddle points. Moreover, as corollaries of the two results above, we not only obtain sufficient and necessary conditions for the existence of global saddle points of some special types of augmented Lagrangian functions mentioned in the literature, but also give some weaker sufficient conditions than the ones in the literature. Compared with our recent work (Wang et al. in Math Oper Res 38:740–760, 2013), the nonlinear augmented Lagrangian functions in this paper are more general and the results in this paper are original. We show that some examples (such as improved barrier augmented Lagrangian) satisfy the assumptions of this paper, but not available in Wang et al. (2013).     

On the structure of integral surfaces near a higher order focus and saddle

In this paper the structure of integral surfaces near a higher order focus and saddle, of ordinary differential equations in complex domain is studied by reducing to the normal form system. The formulae of the normal form system are also given.     

Fanky极大极小不等式的进一步推广及对变分不等式的应用

本文引出广义KKM映象的概念,其包含著名的KKM映象为特例.借助于这一映象,我们给出著名的KKM定理和Fan Ky极大极小不等式以一种新的推广形式.作为应用,我们考虑了变分不等式解的存在性问题.本文结果是引文[1～6]中相应结果的改进和发展.