Existence of four positive periodic solutions for a ratio-dependent predator–prey system with multiple exploited (or harvesting) terms

In this paper, we investigate a non-autonomous ratio-dependent predator–prey model with exploited terms. By means of using coincidence degree theory, we establish the existence of at least four positive periodic solutions for the above model.     

Periodic solutions of a nonautonomous periodic model of population with continuous and discrete time

In this paper, we employ the Mawhin's continuation theorem to study the existence of positive periodic solutions of the nonautonomous periodic model of population with continuous and discrete time. It is interesting that the conditions to guarantee the existence of positive periodic solutions of discrete time model are similar to those for the corresponding continuous time model.     

Existence and exponential convergence of the positive almost periodic solution for a model of hematopoiesis

In this work, we study the existence and global exponential convergence of positive almost periodic solutions for the generalized model of hematopoiesis. Under appropriate conditions, we employ a novel proof to establish some criteria for ensuring that all solutions of this model converge exponentially to the positive almost periodic solution.     

Positive almost periodic solution for a class of Nicholson’s blowflies model with multiple time-varying delays

In this paper, we study the existence and exponential convergence of positive almost periodic solutions for the generalized Nicholson’s blowflies model with multiple time-varying delays. Under proper conditions, we establish some criteria to ensure that the solutions of this model converge locally exponentially to a positive almost periodic solution. Moreover, we give some examples to illustrate our main results.     

一个周期中立型对数种群模型

本文获得了周期中立型对数种群模型N(t)=N(t)(r(t)-α(t)log[N(t-σ)]-b(t)d/dtlog[N(t-r)])的周期正解的存在性及对所有正解的吸引性．     

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。     

New results of existence and stability of periodic solution for a delay multispecies Logarithmic population model

In this Letter, for a general class of delayed periodic multispecies Logarithmic population model, we prove some new results on the existence of positive periodic solutions by contraction principle. The global exponential stability of positive periodic solutions is discussed further, and conditions for exponential convergence are given. The conditions we obtained are weaker than the previously known ones and can be easily reduced to several special cases.     

Positive almost periodic solution for a class of Lasota-Wazewska model with infinite delays

By utilizing a fixed theorem in cones, we study the existence of a unique positive almost periodic solution for a generalized Lasota-Wazewska model with infinite delays. Some sufficient conditions which ensure the existence of a unique positive almost periodic solution are derived and it cannot be obtained by the contraction mapping principle. Furthermore, under proper conditions, we establish some criteria to ensure that all solutions of this model converge exponentially to a positive almost periodic solution. An example is provided to illustrate the effectiveness of the proposed result.     

Four positive periodic solutions to a Lotka–Volterra cooperative system with harvesting terms

In this paper, we establish the existence of four positive periodic solutions for a Lotka–Volterra cooperative system with harvesting terms by using the continuation theorem of coincidence degree.     

Almost periodic solution for Nicholson’s blowflies model with patch structure and linear harvesting terms

In this paper, we study the existence and exponential convergence of positive almost periodic solutions for a class of Nicholson’s blowflies model with patch structure and multiple linear harvesting terms. Under appropriate conditions, we establish some criteria to ensure that the solutions of this system converge locally exponentially to a positive almost periodic solution. Moreover, we give some examples and numerical simulations to illustrate our main results.     

Existence of periodic solutions in a model of respiratory syncytial virus RSV

In this paper we study the existence of a positive periodic solutions for nested models of respiratory syncytial virus RSV, by using a continuation theorem based on coincidence degree theory. Conditions for the existence of periodic solutions in the model are given. Numerical simulations related to the transmission of respiratory syncytial virus in Madrid and Rio Janeiro are included.     

EXISTENCE OF MULTIPLE POSITIVE PERIODIC SOLUTIONS TO A CLASS OF INTEGRO-DIFFERENTIAL EQUATION

In this paper,by the Avery-Henderson fixed point theorem,we investigate the existence of multiple positive periodic solutions to a class of integro-differential equation. Some suficient conditions are obtained for the existence of multiple positive periodic solutions.     

EXISTENCE OF TWO PERIODIC SOLUTIONS TO A RATIO-DEPENDENT PREDATOR-PREY MODEL WITH PREDATOR'S HARVEST

In this paper,we study a non-autonomous ratio-dependent predator-prey model with predator's harvest.By means of the coincidence degree theory,we establish sufficient conditions for the existence of at least two positive periodic solutions of this model.     

脉冲泛函微分方程的正周期解

运用Leray-Schauder不动点定理研究一类脉冲泛函微分方程的正周期解的存在性,获得了存在正周期解的充分条件,改进了已知文献中的结果.     

Positive periodic solution for a neutral delay competitive system

In this paper we study the existence of positive periodic solutions for a class of neutral type competitive system with delay. Applying the continuation theorem of coincidence degree theory, a general criteria on the existence of positive periodic solutions are established. Some the related results are generalized and improved. It is shown that the arguments delays have no effect on the existence positive periodic solution of system.     

一类无穷时滞周期Lotka-Volterra型系统的正周期解

该文研究一类无穷时滞周期Ｌｏｔｋａ Ｖｏｌｔｅｒｒａ型系统正周期解的存在性．应用Ｓｃｈａｕｄｅｒ不动 点定理得到了一个比较一般的正周期解存在定理．文献［１,２］中的主要结果被改进和推广．     

EXISTENCE OF MULTIPLE PERIODIC SOLUTIONS TO THREE-SPECIES DELAYED LOTKA-VOLTERRA MODEL WITH DISPERSION AND HARVESTING

The positive periodic solutions to a three-species delayed Lotka-Volterra model with dispersion and harvesting terms are studied in this paper. By the coincidence degree theory, the sufficient conditions for existence of eight positive periodic solutions to the model are obtained.     

A qualitative study on general Gause-type predator-prey models with constant diffusion rates

In this paper, we study the qualitative behavior of non-constant positive solutions on a general Gause-type predator-prey model with constant diffusion rates under homogeneous Neumann boundary condition. We show the existence and non-existence of non-constant positive steady-state solutions by the effects of the induced diffusion rates. In addition, we investigate the asymptotic behavior of spatially inhomogeneous solutions, local existence of periodic solutions, and diffusion-driven instability in some eigenmode.     

Existence of at Least Two Periodic Solutions of a Ratio-dependent Predator-prey Model with Exploited Term

In this paper, we study a non-autonomous ratio-dependent predator-prey model with exploited term. By means of the coincidence degree theory, we establish a sufficient condition for the existence of at least two positive periodic solutions of this model.     

A Landesman-Lazer type condition for second-order differential equations with a singularity at resonance

In this paper, we are concerned with the existence of positive periodic solutions for second-order differential equations with a singularity at resonance. A Landesman-Lazer type condition is given to obtain the existence of positive periodic solutions using phase-plane analysis method and topological degree method.