具有时滞的保守系统的2π周期解

对于如下的保守系统■ gradG(x)=P(t)=P(t 2π) (1)的2π周期解的存在性与唯一性,很早以来就受到重视,1974年 R.Kannan 证明了定理 A.设 P(t)∈C(R,P~n)是 2π周期的,G∈C~2(R~n,R),如果存在非负整数 M 及正数 p,q 满足     

一阶非线性微分方程组的反周期解

讨论了一阶非线性常微分方程组x′=G(t,x(t)),x(0)=-x(π),x∈R~n的反周期解问题,给出了此类方程组解的存在惟一性的判定定理,并通过实例对所得定理进行了进一步解释说明.     

计算简单分歧点的Weber辅助方程离散Newton法

1.引言 本文考虑单参数有限维非线性方程组G:??R~n×R~1→R~n, G(x,λ)=0 x∈R~n,λ∈R (1.1)的数值求解.方程组(1.1)的解在集合     

ON THE EXISTENCE OF PERIODIC SOLUTIONS FOR LIENARD SYSTEMS

<正> In this paper we study the existence of periodic solutions for n-dimensional Liénard syste-ms of the formx″+((?)~2F(x))/((?)x~2)x′+grad G(x)=e(t), (1.1)where F∈C~2(R~n,R),G∈C~1(R~n,R),e∈C(R,R~n)and e(t)≡e(t+T)for some con-stant T>0.By((?)~2F(x))/((?)x~2),we denote the Hessian Matrix of F at x.     

共振情形下周期边值问题正解的全局分歧

考虑共振情形下二阶常微分方程周期边值问题{u'=f(t,u), t∈(0,2π), u(0)=u(2π), u'(0)=u'(2π)正解的全局分歧,其中f:[0,2π]×R→R(R=(-∞,+∞))为连续函数.运用Dancer全局分歧定理获得了上述问题至少存在一个正解的若干充分条件,这些充分条件中所涉及的值是最优的.     

Liénard方程周期解的存在唯一与唯二性问题

本文考虑微分方程 x+f(x)x+g(x)=p(t),其中g∈C~1(R)为严格递减,f ∈ C(R),p(t)为2π周期的连续函数,给出周期解的存在唯一的充要条件;在f(x)=c,g(x)严格凸函数且跨越第一共振点零时,给出唯二性定理。     

广义Lienard方程周期解的存在唯一性

应用整体反函数理论证明了广义L ienard方程a(t)x" f(x,x′)x′ g(t,x)=e(t),x(0)-x(2π)=x(′0)-x′(2π)=0,周期解的存在唯一性,并由此得到它在几种特殊情况下周期解的存在唯一性定理.     

Moser扭转定理在Lgrange稳定性中的应用

本文利用Moser扭转定理证明了一类Duffing方程x″+g(x)=e(t)的Lagrange稳定性,其中e(t)以1为周期,g:R→R具有下列性质:当x≥d0时,g(x)是超线性的;当x≤-d0时,9(x)是次线性的,其中d0悬一正常数.     

函数因子法——非线性方程组求解中处理奇异问题的一种新方法

§1.引言 非线性方程组 F(x)=0,F:D?R~n→R~n (1.1)嵌入参数t,构成同伦H:[0,T]×D?R~(n 1)→R~n,使得 H(0,x~0)=0,H(T,x)=F(x),(1.2)这里T可以是有限的或 ∞,当T为 ∞时以极限过程代替求值.若 H(t.x)=0(1.3)存在连续解x(t):[0,T]→D,则非线性方程组(1.1)的解x~*=x(T).若(1.3)的解     

广义Lienard方程边值问题

By coincidence degree,the existence of solution to the boundary value problem of a generalized Liénard equation a(t)x＂+F(x,x′)x′+g(x)=e(t),x(0)=x(2π),x′(0)=x′(2π)is proved,where a∈C1[0,2π],a(t)>0(0≤t≤2π),a(0)=a(2π),F(x,y)=f(x)+α| y|β,α>0,β>0 are all constants,f∈C(R,R),e∈C[0,2π]. An example is given as an application.     

一类特殊分布纪录值之和的中心极限定理

摘要：设{X，Xn,n≥1)为独立同分布的服从某连续分布F的随机变量序列，X^(1)=X1，X^(2),X^(3),…为其纪录值序列．令ψ(u)=F^-1(1-e^-u)．其中F^-1是F的反函数．本文研究当ψ(u)=log^pu时Tn=∑k=1^nX^(k)=^dn∑k=1^nψ(Sn)的极限性质．解决了户为所有正整数时Tn的中心极限定理．     

ADDITIVE FAMILIES OF INVARIANTS OF FORMS OF DEGREE d

Abstract

Let d be a positive integer, and F be a field of characteristic zero. Suppose that for each positive integer n, I _n, is a GL _n,(F)- invariant of forms of degree d in x₁, …, x _n, over F. We call {I _n} an additive family of invariants if I _p+q (f ⊥ g) = I _p(f).I _q(g) whenever f; g are forms of degree d over F in x _l, …, x _p; …, x _q respectively, and where (f ⊥ g)(x _l, …, x _p+q) = f(x ₁, …, x _p,) + g (x _p+1, …, x _p+q). It is well-known that the family of discriminants of the quadratic forms is additive. We prove that in odd degree d each invariant in an additive family must be a constant. We also give an example in each even degree d of a nontrivial family of invariants of the forms of degree d. The proofs depend on the symbolic method for representing invariants of a form, which we review.     

COMPARISON OF PRODUCTS OF THE VARIETIES OF LIE ALGEBRAS

Abstract

In Fortes (2001), we introduced a notion of order for associative pairs and we obtained a Goldie-like characterization of left orders in a semiprime pair coinciding with its socle. In this paper, we take up again that notion of order to establish a Faith-Utumi theorem, which studies left orders in a prime pair coinciding with its socle.     

有限Abel群上子集等价类的计数

设G为一有限Abel群，|G|=v,D1,D2是G的两个子集，如果存在t∈Zv,(t,v)=1,s∈G使D1＝tD2 s，则称D1与D2是等价的。文中给出了G的k-子集等价类的计数公式，同时也给出了G的的所有子集等价类的计数公式。     

ESTIMATES OF N-FUNCTION AND m-FUNCTION OF MEROMORPHIC SOLUTIONS OF SYSTEMS OF COMPLEX DIFFERENCE EQUATIONS

We apply Nevanlinna theory of the value distribution of meromorphic functions to study the properties of Nevanlinna counting function and proximity function of meromorphic solutions of a type of systems of complex difference equations. Our results can give estimates on the proximity function and the counting function of solutions of systems of difference equations. This implies that solutions have a relatively large number of poles. It extend some result concerning difference equations to the systems of difference equations.     

一类pnm阶群的构造

本文研究了一类特殊的pnm阶有限群的构造.利用求解数论同余方程的方法和群的扩张理论,得到了具有m阶循环正规子群,其补子群为循环群的Pnm阶有限群的构造及相关的计数定理.     

小康判别函数的建立与分析

近几年，国内在研究小康水平的定量指标分析中，应用较多的有综合评分法、层次分析法和模糊识别法。这几种方法比单项指标更全面、灵活，但在权数的确定上都难以克服人为因素的影响。当指标之间存在两个或两个以上的高度相关时，对问题的研究总存在一定的局限性。为了科学地研究小康问题，本文基于判别分析，建立城市小康的判别系数，来综合评价出我国城市小康水平的定量标准。