一类二阶具偏差变元的微分方程周期解

本文利用重合度理论研究一类二阶具偏差变元的微分方程x＇＇（t）+f（t,x（t）,x（t-τ0（t）））x＇（t）+β（t）g（x（t-τ1（t）））=p（t）的周期解问题,得到了存在周期解的新的结果.     

一类二阶泛函微分方程周期解存在性问题

利用重合度理论研究一类二阶泛函微分方程x″(t)+f(t,x_t)x′~n+β(t)g(x(t-τ(t)))=p(t)的周期解问题,本文得到了周期解存在的新的结果。     

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。     

Optimal estimates on rotation number of almost periodic systems

In this paper, we will give some optimal estimates on the rotation number of the linear equation $\ifmmode\expandafter\ddot\else\expandafter\"\fi{x} + p(t)x = 0,$\ifmmode\expandafter\ddot\else\expandafter\"\fi{x} + p(t)x = 0, and that of the asymmetric equation: $\ifmmode\expandafter\ddot\else\expandafter\"\fi{x} + p(t)x_{ + } + q(t)x_{ - } = 0,$\ifmmode\expandafter\ddot\else\expandafter\"\fi{x} + p(t)x_{ + } + q(t)x_{ - } = 0, where p(t) and q(t) are almost periodic functions and x ₊ = max{ x,0} ,  x _- = min{ x,0} .x_{ + } = \max \{ x,0\} ,\;x_{ - } = \min \{ x,0\} . These estimates are obtained by introducing some kind of new norms in the spaces of almost periodic functions.     

Periodic solutions of singular second order equations at resonance

In this paper, we study the existence of positive periodic solutions for singular second order equations x" + n²/4x+h(x) = p(t), where h has a singularity at the origin and n is a positive integer. We give an explicit condition to ensure the existence of positive periodic solutions when h is an unbounded perturbation at infinity by using qualitative analysis and topological degree theory.     

Duffing方程的奇异点方法

设g∈C2(R),p(t)为连续的2π周期函数.考虑Duffing方程x+g(x)=p(t),x(O)=x(2π),x(0)=x(2π),笔者应用奇点理论,证明了Duffing算子Fx(t)=x(t)+g(x(t)).当g(x)为严格凸且g’(x)渐近跨越第一共振点0时, F整体等价于Whitney意义下的fold映射,特别地,获得2π周期解的不存在性、唯一性与唯二性定理.     

On the existence of periodic solutions of Rayleigh equations

In this paper, we study the existence of periodic solutions of Rayleigh equation

A General Comparison Result for Higher Order Nonlinear Difference Equations With Deviating Arguments

The authors consider m -th order nonlinear difference equations of the form D m p x n + i h j ( n , x s j ( n ) )=0, j =1,2,( E j ) where m S 1, n ] N 0 ={0,1,2,…}, D 0 p x n = x n , D i p x n = p n i j ( D i m 1 p x n ), i =1,2,…, m , j x n = x n +1 m x n , { p n 1 },…,{ p n m } are real sequences, p n i >0, and p n m L 1. In Eq. ( E 1 ) , p = a and p n i = a n i , and in Eq. ( E 2 ) , p = A and p n i = A n i , i =1,2,…, m . Here, { s j ( n )} are sequences of nonnegative integers with s j ( n ) M X as n M X , and h j : N 0 2 R M R is continuous with uh j ( n , u )>0 for u p 0. They prove a comparison result on the oscillation of solutions and the asymptotic behavior of nonoscillatory solutions of Eq. ( E j ) for j =1,2. Examples illustrating the results are also included.     

二阶微分系统奇异正定超线性周期边值问题的多重正解

主要研究了二阶微分系统具有奇异正定超线性周期边值问题多重正解的存在性问题,利用Leray-Schauder抉择定理和锥不动点定理给出了奇异正定超线性周期边值问题-(p(t)x′)′+q1(t)x=f1(t,x,y),t∈I=[0,1]-(p(t)y′)′+q2(t)y=f2(t,x,y)x(0)=x(1),x[1](0)=x[1](1)y(0)=y(1),y[1](0)=y[1](1)(1.1)的多重正解的存在性,其中非线性项fi(t,x,y)(i=1,2)在x=∞,y=∞点处超线性,在(x,y)=(0,0)处具有奇性.这里定义x[1](t)=p(t)x′(t),y[1](t)=p(t)y′(t)为准导数,其中系数p(t),qi(t)(i=1,2)是定义在[0,1]上的可测函数,且p(t)>0,qi(t)>0(i=1,2),a.e[0,1],fi(t,x,y)∈C(I×R×R,R+),R+=(0,+∞).     

概周期摆型方程无界解的存在性

对摆型方程x+Gx(x,t)=p(t),其中G(x,t)∈C1(R2)关于变量x是1周期的,并且sup(x,t)∈R2|Gx(x,t)|<+∞,limsupt→∞{supx∈R}=0,p(t)是平均值非零的概周期函数,证明了在柱面S1×R上方程具有无穷多的无界解.     

一类中立型脉冲积分微分方程概周期解的存在性和唯一性

考虑具连续时滞和离散时滞的中立型脉冲积分微分方程去{d/dt[x(t)+q∑j=1ej(t)x(t-δj(t))]=A(t,x(t))x(t)+t∫-∞C(t,s)x(s)ds+p∑j=1gj(t,x(t=Ti(t)))+b(t),t≠tk,tktk+1,△x(t)=Bkx(t)+Ik(x(t))+γk,.t=tk,k∈Z.概周期解的存在性和唯一性问题.利用线性系统指数二分性理论和不动点定理,莸得了保证中立型系统概周期解存在性和唯一性的充分条件,推广了相关文献的主要结果.     

On a system of second order differential equations with periodic impulse coefficients

A thorough investigation of the systemd~2y(x):dx~2 p(x)y(x)=0with periodic impulse coefficientsp(x)={1,0≤xx_0>0) -η, x_0≤x<2π(η>0)p(x)=p(x 2π),-∞相似文献   

一类高阶中立型泛函微分方程周期解的存在性

研究了一类高阶非线性中立型泛函微分方程x~((2n))(t)+cx~((2n))(t-τ)+f(x)x′+bx(t)+g(x(t-σ))=p(t)周期解的存在性,利用分析技巧结合重合度理论给出了该方程存在周期解的充分性定理.     

On existence of positive periodic solutions of a kind of Rayleigh equation with a deviating argument

The existence of positive periodic solutions for a kind of Rayleigh equation with a deviating argument

Nonlinear integrodifferential equations anda priori bounds on periodic solutions

Summary This paper studies the existence of aperiodic solution of a nonlinear integrodifferential system of the form , for each continuous periodic function p and under suitable assumptions on f, k and g. A topological transversality method is employed to obtain the existence of periodic solutions. This method relies ona priori bounds on periodic solutions. Several examples are provided where a variant of Liapunov's direct method is employed to obtaina priori bounds on periodic solutions.     

Oscillation and Global Attractivity in a Nonlinear Delay Periodic Model of Population Dynamics

In this article we shall consider the following nonlinear delay differential equation $$x'(t) + p(t)x(t)-\frac {q(t)x(t)}{r + x^{n}(t-m\omega )} = 0\eqno (*)$$ where m and n are positive integers, p ( t ) and q ( t ) are positive periodic functions of period y . In the nondelay case we shall show that (*) has a unique positive periodic solution $ \overline {x}(t), $ and provide sufficient conditions for the global attractivity of $ \overline {x}(t) $ . In the delay case we shall present sufficient conditions for the oscillation of all positive solutions of (*) about $ \overline {x}(t), $ and establish sufficient conditions for the global attractivity of $ \overline {x}(t). $     

广义Ramanujan-Nagell方程x~2+D~m=p~n

设D是大于1的正整数,p是不能整除D的素数.本文证明了:当D=3a~2+1,p=4a~2+1,其中a是正整数时,除了(D,p)=(4,5)这一情况以外,方程x~2+D~m=p~n仅有2组正整数解(x,m,n)=(a,1,1)和(8a~3+3a,1,3).根据上述结果得到了该方程解数的最佳上界.     

On the existence of periodic solutions for the third-order nonlinear ordinary differential equations

In this paper,the existence of periodic solution for the third-order nonlinear ordinarydifferential equation of the form -^x f(-^x) g(-^x) h(x)=p(t) is consldered,where f,g,h andp are the continuous functlons, and p (t T) =p (t). By using the Leray-Schauder degreemethod,some sufficient conditions to guarantee the existence of T periodic solution for the equation are obtained. Some previous results are extended and improved.     

A Landesman-Lazer Type Theorem for Periodic Solutions of the Resonant Asymmetric ρ-Laplacian Equation

In this paper, we give a Landesman-Lazer type theorem for periodic solutions of the asymmetric 1-dimensional p-Laplacian equation -（｜x＇｜^p-2x＇）＇=λ｜x｜^p-2x＋＋μ｜x｜^p-2x-＋f（t,x）with periodic boundary value.     

一类二阶n-维中立型微分系统周期解问题

笔者利用重合度原理研究一类二阶n-维中立型微分系统(d2)/(dt2)(x(t)-Cx(t- ))+d/(dt)gradF(x(t))+gradG(x(t-τ(t)))=p(t)的周期解问题,得到了周期解存在性的新结果,推广了已有工作中相应的结论.