Existence of positive periodic solutions for a functional differential equation with a parameter

In this paper, we study the existence, multiplicity and nonexistence of positive ω$\omega$-periodic solutions for a kind of nonautonomous functional differential equation by employing the fixed point theorem in cones. Some new results are obtained. As an application of our results, we discuss the existence of a positive periodic solution for a class of models of blood cell production with a parameter, which has not been investigated by using previous methods.     

Singularly perturbed differential inclusions: An averaging approach

We consider nonlinear, singularly perturbed differential inclusions and apply the averaging method in order to construct a limit differential inclusion for slow motion. The main approximation result states that the existence and regularity of the limit differential inclusion suffice to describe the limit behavior of the slow motion. We give explicit approximation rates for the uniform convergence on compact time intervals. The approach works under controllability or stability properties of fast motion.     

Existence of nontrivial periodic solutions of certain nonautonomous ordinary differential equations

Degree theory is used to establish sufficient conditions for the existence of a non-trivial periodic solution of the vector differential equation f(D)x + BMg(D)x = 0, which generalises the feedback control equation. These conditions require that the matrix M should satisfy two elliptic ball criteria, one of which is relevant near the origin of the phase space and the other near the point at infinity.     

一类非线性中立型微分方程周期解的存在性

利用有关不等式,本文首先获得一类非线性中立型微分方程一个新的先验估计.基于解的先验估计以及迭合度理论,给出了这类中立型微分方程存在周期解的一个充分条件.     

具偏差变元高阶Lienard方程周期解存在性

利用重合度理论,研究了一类具偏差变元高阶L ienard型方程周期解的存在性,获得了该方程至少存在一个周期解的充分条件.     

含参数泛函微分方程概周期正解的存在性

研究了一类含参数泛函微分方程概周期正解的存在性问题.结合有界性及渐近概周期性获得了系统存在概周期正解的几组充分条件,并将结果应用于几类种群动力学模型,分别获得了系统在概周期环境下存在概周期解的一组充分条件.     

Existence of periodic solutions of differential systems with small parameters

In this article, we use a new method—reflecting function to study the existence of periodic solutions of some periodic systems with small parameters.     

非自治时滞微分方程正周期解的存在性

应用Krasnoselskii锥映射不动点定理，研究了具一般时滞非线性非自治Logistic方程的ω-周期解的存在性，获得了存在正周期解的充分条件．     

Existence of positive periodic solutions of periodic boundary value problem for second order ordinary differential equations

In this paper the existence of positive solutions are obtained for a class of second order differential equations. The proof is based on the fixed point index theory in cones.     

Existence of periodic solutions of a neuronic equation

In this paper, a planar system reduced from a neuronic equation is investigated. By using the qualitative analysis method of ordinary differential equations, we obtain conditions for the existence of a unique limit cycle surrounding a singular point and one or two limit cycles simultaneously surrounding three singular points.     

Periodic solutions for a nonautonomous ordinary differential equation

We consider the nonautonomous differential equation of second order x^″+a(t)x−b(t)x²+c(t)x³=0, where a(t),b(t),c(t) are T-periodic functions. This is a biomathematical model of an aneurysm in the circle of Willis. We prove the existence of at least two positive T-periodic solutions for this equation, using coincidence degree theories.