拓扑定理及其在超线性脉冲方程中的应用

本文研究一类含脉冲的非保守超线性方程的周期振动问题.通过详细刻画跳跃映射的角度函数,并应用相平面分析方法,本文证明方程的Poincaré映射有无穷多个不动点,而这些不动点对应了方程的无穷多个2π周期解.由于本文考虑的Poincaré映射不是同胚,所以,本文重新构造并证明了一个拓扑定理用于替代经典的Poincaré-Birkhoff扭转不动点定理.     

常微分方程解的存在区间和周期解

讨论解的存在区间,说明周期函数如何是周期解以及它和Poincaré映射的关系.对周期的Riccati方程研究了周期解的个数,是文[8]中的定理1的一个补充,同时也研究了周期捕获的人口方程解的存在区间和周期解问题.     

碰撞Hamiltonian系统的无穷小周期解

本文通过适当的坐标变换将碰撞振子的相平面转变为全平面,应用Poincaré-Birkhoff扭转定理,证明了在原点附近超线性碰撞振子的无穷多弹性周期解的存在性,从而推广了已有的结果.     

脉冲条件下Liénard方程周期解的保持性

本文研究带有脉冲的Lienard方程的周期解的存在性问题.我们通过分析Poincaré映射在脉冲点处的变化特征,利用Poincare-Bohl不动点定理证明:在一串脉冲点于时间轴上具有周期分布特征的情况以及适当的脉冲条件之下,如果位势函数满足Lipschitz条件,而强迫项又是周期函数,则Lienard方程x″+f (x)x′+g(x)=p(t)仍然保持周期解的存在性.另外,我们给出了一个具体的Liénard方程例子,来佐证本文中主要结果的有效性.     

以抛物弓形为边界的周期环域的三次系统的Poincaré分支

本文以抛物弓形为边界的周期环域的三次系统的Poincaré分支为例,说明具有相同边界的周期环域的相同次数的多项式系统的Poincaré分支,由于周期环域内闭轨的不同,它们所对应的Abel积分也不同,所以它们的Poincaré分支所能分支出极限环的个数也是不同的.     

Poincaré非线性振动理论在连续介质力学中的推广(Ⅰ)——基本理论与方法*

本文将离散介质的Poincaré非线性振动理论[1]向连续介质力学推广,做了初步尝试。首先讨论在非共振与共振情况下,连续介质线性强迫振动周期解,及其周期解存在条件。进而运用线性理论结果,将Poincaré理论中的主要结论推广到连续介质非线性振动问题中去。此外,本文提出并建议用偏微分方程直接摄动与加权积分方法,计算共振区内的周期解。     

一类受迫Liénard系统的最终零解

寻找一类带有时间依赖强迫项的Liénard系统的最终零解,这是一种当t±∞时趋于0的特殊有界解.由于不是微扰的Hamilton系统,所以不能使用Melnikov方法来判断最终零解的存在性.研究了一个逼近原系统的周期受迫系统序列的周期解序列,并且证明这个周期解序列有一个收敛子列,其极限就是原受迫Liénard系统的最终零解.其中使用Schauder不动点定理解决了由非Hamilton造成的困难.     

一维周期方程的周期解问题

本文给出研究一维周期微分方程周期解的若干方法,包括利用Poincaré映射来判定周期解的个数、零解的稳定性及其重数、规范形方法和平均法等,其中既有对已有结论的总结和改进,又包含了一些新的结论.     

强迫摆型碰撞振子的弹性周期解

本文考虑一类具有强迫力的摆型碰撞振子无穷多次调和的弹性周期解的存在性.通过坐标变换的方法把碰撞系统转化为定义在全平面上的等价系统,再运用相平面分析的方法对变换后系统的解的动力行为进行分析,通过在改进的Poincar映射上应用Poincar-Birkhoff扭转定理得到了无穷多次调和的弹性周期解的存在性.     

运用Poincaré-Miranda定理数值验证变分不等式解的存在性

本文运用Poincaré-Miranda定理数值验证变分不等式问题解的存在性. 证明这一新方法相对于已有的方法更具有普遍性, 并通过数值例子说明本方法的高效性.     

EXISTENCE OF PERIODIC SOLUTIONS OF A CLASS OF SECOND-ORDER NON-AUTONOMOUS SYSTEMS

In this paper, we are concerned with the existence of periodic solutions of second-order non-autonomous systems. By applying the Schauder''s fixed point theorem and Miranda''s theorem, a new existence result of periodic solutions is established.     

高维时滞周期的Kolmogorov型系统的正周期解

本文应用Ｂａｎａｃｈ空间中的Ｈｏｒｎ不动点得到了高维时滞的周期Ｋｏｌｍｏｇｏｒｏｖ型生态系统的正周期解存在性定理,作为这个定理的应用,讨论了几类时滞的周期ＬｏｔｋａＶｏｌｔｅｒｒａ型系统的正周期解的存在性问题,建立了新的实用的判别准则。     

时标上具有阶段结构的三种群捕食系统的周期解

研究了时标上具有阶段结构的三种群捕食系统.运用时标上连续拓扑度定理,得到了系统存在周期解的充分条件.其研究方法使系统的连续时间情形和离散时间情形的周期解问题得到了统一,被广泛地应用来研究微分方程和差分方程的周期解的存在问题.     

无穷时滞的泛函微分方程的多重正周期解(英文)

In this paper, we investigate the existence of multiple positive periodic solutions for functional differential equations with infinite delay by applying the Krasnoselskii fixed point theorem for cone map and the Leggett-Williams fixed point theorem.     

Periodic solution of neutral Lotka-Volterra system with periodic delays

A nonautonomous n-species Lotka-Volterra system with neutral delays is investigated. A set of verifiable sufficient conditions is derived for the existence of at least one strictly positive periodic solution of this Lotka-Volterra system by applying an existence theorem and some analysis techniques, where the assumptions of the existence theorem are different from that of Gaines and Mawhin's continuation theorem [R.E. Gaines, J.L. Mawhin, Coincidence Degree and Nonlinear Differential Equations, Springer-Verlag, Berlin, 1977] and that of abstract continuation theory for k-set contraction [W. Petryshyn, Z. Yu, Existence theorem for periodic solutions of higher order nonlinear periodic boundary value problems, Nonlinear Anal. 6 (1982) 943-969]. Moreover, a problem proposed by Freedman and Wu [H.I. Freedman, J. Wu, Periodic solution of single species models with periodic delay, SIAM J. Math. Anal. 23 (1992) 689-701] is answered.     

一类二阶奇异周期边值问题正解的存在性

利用锥上的不动点定理得到了一类二阶奇异周期边值问题在一定条件下正题的存在性,其中非线性项显含一阶导数且允许在u=0处有奇性,从而推广和丰富了已有文献的结果.     

非自治Kolmogorov竞争系统的严格正解

In this paper, the existence of strictly positive solutions for N species normutonomous Kolmogorov competition systems is studied. By applying the Schauder‘s flxed pointtheorem some new sufficient conditions are established. In particular, for the almost periodicsystem, tile existence of strictly positive almost periodic solutiorts is obtained, Some previousresults are improved and generalized.     

Existence of periodic solution of order one of planar impulsive autonomous system

Based on the situation that all the recent research about state-dependent impulsive differential equations is focused on systems which have explicit solutions, this paper try to consider those systems with state-dependent impulsion which have not explicit solutions. We get an existence theorem of periodic solution of order one for a general planar autonomous impulsive system, and, by applying it to a special state-dependent impulsive differential equations we get the concrete conditions of existence of one-order periodic solution of that special system.     

LOCAL AND GLOBAL HOPF BIFURCATIONS FOR A PREDATOR-PREY SYSTEM WITH TWO DELAYS

In this paper, the Leslie predator-prey system with two delays is studied. The stability of the positive equilibrium is discussed by analyzing the associated characteristic transcendental equation. The direction and stability of the bifurcating periodic solutions are determined by applying the center manifold theorem and normal form theory. The conditions to guarantee the global existence of periodic solutions are given.