ANALYSIS OF A SUSCEPTIBLE-EXPOSED-INFECTED EPIDEMIC MODEL WITH RANDOM PERTURBATION AND VARYING POPULATION SIZE

In this paper, we study a type of susceptible-exposed-infected (SEI) epidemic model with varying population size and introduce the random perturbation of the constant contact rate into the SEI epidemic model due to the universal existence of fluctuations. Under some moderate conditions, the density of the exposed and the infected individuals exponentially approaches zero almost surely are derived. Furthermore, the stochastic SEI epidemic model admits a stationary distribution around the endemic equilibrium, and the solution is ergodic. Some numerical simulations are carried out to demonstrate the efficiency of the main results.     

一类带收获率的捕食-食饵模型的共存解

讨论了齐次Neumann边界条件下食饵有外界常收获率的捕食-食饵模型的共存态首先分析了正常数解的稳定性以及非常数正平衡解不存在的条件.其次,基于对平衡解的先验估计,利用拓扑度理论,给出了此平衡态系统非常数正解的存在性.     

QUALITATIVE ANALYSIS OF A DICRETE POPULATION MODEL

1IntroductionandPreliminariesInthispapertweconsiderthenonlinearbackwarddifferenceequationwhereafb,candkareconstantsandsatisfyEq.(1.l)maybeviewedasadiscreteanalogueofthemodelofsinglespeciespopulatiollwithaquadraticper-capitagrowthratewhicllwasstudiedbyGopalsalllyandLadasin[2].Therefore,wesaythatEq.(1.1)isadiscretepopulationmodel.Inarecelltpaper[5],Rodriguesstudiedanotherdiscreteanologueof(1.3),.namely,thefollowingforwarddifferenceequationalldobtailledsomeresultsfortilequalitativebehaviorsofso…     

DYNAMICAL BEHAVIOR OF AN INNOVATION DIFFUSION MODEL WITH INTRA-SPECIFIC COMPETITION BETWEEN COMPETING ADOPTERS

In this paper,we proposed an innovation diffusion model with three compartments to investigate the diffusion of an innovation（product） in a particular region.The model exhibits two equilibria,namely,the adopter-free and an interior equilibrium.The existence and local stability of the adopter-free and interior equilibria are explored in terms of the effective Basic Influence Number（BIN） R_A.It is investigated that the adopter free steady-state is stable if R_A <1.By conside...     

EFFECTS OF A TOXICANT ON A SINGLE-SPECIES POPULATION WITH PARTIAL POLLUTION TOLERANCE IN A POLLUTED ENVIRONMENT

We study a model for the long-term behavior of a single-species population with some degree of pollution tolerance in a polluted environment. The model consists of three ordinary differential equations: one for the population density, one for the amount of toxicant inside the living organisms, and one for the amount of toxicant in the environment. We derive sufficient conditions for the persistence and the extinction of the population depending on the exogenous input rate of the toxicant into the environment and the level of pollution tolerance of the organisms. Numerical simulations are carried out to illustrate our main results.     

具Allee反应的时滞扩散单种群增长模型的波前解

本文利用上、下解技巧和单调迭代法,研究了具Allee反应的时滞扩散单种群增长模型的波前解,给出了波前解存在的条件.     

具Allee反应的时滞扩散单种群增长模型的波前解

本文利用上、下解技巧和单调迭代法,研究了具Allee反应的时滞扩散单种群增长模型的波前解, 给出了波前解存在的条件.     

LONG-TERM DYNAMIC ANALYSIS OF ENDANGERED SPECIES WITH STAGE-STRUCTURE AND MIGRATIONS IN POLLUTED ENVIRONMENTS

We propose a stochastic stage-structured single-species model with migrations and hunting within a polluted environment, where the species is separated into two groups: the immature and the mature, which migrates from one patch to another with different migration rates. By constructing a Lyapunov function, together with stochastic analysis approach, the stochastic single-species model admits a unique global positive solution. We then utilize the comparison theorem of stochastic differential equations to investigate the extinction and persistence of solution to stochastic single-species model. The main results indicate that the species densities all depend on the intensities of random perturbations within both patches. As a consequence, we further provide several strategies for protecting endangered species within protected and unprotected patches.     

企业与银行交易关系动态模型分析

本文采用动态分析的方法,分析介绍企业融资与以银行为代表的金融机构可能发生的交易关系,论述了以利益最大化为目标的银企双方在贷借活动中可以通过建立相互信赖的长期交易契约未达到节约投资资金使用成本的一个理论依据．指出了企业“名声”所具有的经济价值能减少经济活动中的机会主义行为,银行的“审查能力”能挽救陷入流动性资金不足的企业免于破产的作用．分析的结果可能会对银行商业化、企业现代化及投资管理决策提供一个参考．     

OPTIMAL CONTROL OF A POPULATION DYNAMICS MODEL WITH HYSTERESIS

This paper addresses a nonlinear partial differential control system arising in population dynamics.The system consist of three diffusion equations describing the evolutions of three biological species:prey,predator,and food for the prey or vegetation.The equation for the food density incorporates a hysteresis operator of generalized stop type accounting for underlying hysteresis effects occurring in the dynamical process.We study the problem of minimization of a given integral cost functional o...     

QUALITATIVE ANALYSIS OF BOBWHITE QUAIL POPULATION MODEL

In this paper, the qualitative behavior of solutions of the bobwhite quail pop-ulation modelwhere 0   

带扩散项单种群模型的精确能控性

本文研究了一类单种群生态模型的精确能控性问题.利用线性化系统的Carleman估计和Kakutani不动点定理,证明了该模型稳态解的局部能控性.它反应了外部控制在种群演变过程中的影响作用.     

COMPETITION AND COOPERATION IN A DYNAMICAL MODEL OF NATURAL RESOURCES

Abstract In this paper, we propose a model describing the commercial exploitation of a common renewable resource by a population of strategically interacting agents. Players can cooperate or compete; cooperators maximize the payoff of their group while defectors maximize their own profit. The partition of the players into two groups, defectors and cooperators, results from the players' choices, so it is not predetermined. This partition is decided as a Nash equilibrium of a static game. It is shown that different types of players can exist in an equilibrium; more precisely, depending on the parameter values such as resource stock, cost, and so on, there might be equilibria only with defectors, cooperators, or with a combination of cooperators and defectors. In any case the total harvest depends on the renewable resource stock, so it influences agents' positions. It is assumed that at each time period the agents harvest according to Nash equilibrium, which can be combined with a dynamic model describing the evolution of fish population. A complete analysis of the equilibria is presented and their stability is analysed. The effect of the different Nash equilibria on the stability of the fish stock, showing that full cooperation is the most stable case, is examined.     

具有扩散病毒感染群体动力学模型的稳定性与Hopf分歧

讨论了一个具有诺依曼边界条件扩散病毒感染群体动力学模型.证明了模型正常数平衡点的稳定性和扩散引起的Hopf分歧的存在性.     

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.     

一类非线性人口系统的稳定性和振荡

周期现象和振荡是非保守系统中存在着的极为普遍的现象,K.E.Swick 和 M.E.Gurtin & R.c.MacCamy 就几种描述生态演化的非线性动力模型讨论了系统周期解的存在性.由于周期解是系统的一种特殊的平衡态,对这种现象的研究无论从理论上还是实践上都有明显的意义,本文的目的就是在研究一类非线性人口发展方程稳定性的     

关于捕食者种群具有阶段结构和疾病的捕食-被捕食模型(英文)

本文研究了捕食者种群具有阶段结构和疾病的捕食-被捕食模型.利用比较定理、分析特征方程和迭代的技巧,得到了模型永久持续生存和模型的非负平衡位置稳定的充分性条件.通过对结果的分析我们可以给出疾病的基本再生数,这对疾病的防治有很大的意义.     

一类具有常恢复率且总人口变化的SEIS传染病模型的稳定性

This paper considers an SEIS epidemic model with infectious force in the latent period and a general population-size dependent contact rate.A threshold parameter R is identified.If R≤1,the disease-free equilibrium O is globally stable.IfR>1,there is a unique endemic equilibrium and O is unstable.For two important special cases of bilinear and standard incidence,sufficient conditions for the global stability of this endemic equilibrium are given.The same qualitative results are obtained provided the threshold is more than unity for the corresponding SEIS model with no infectious force in the latent period.Some existing results are extended and improved.     

EDGE PERMEABILITY AND POPULATION PERSISTENCE IN ISOLATED HABITAT PATCHES

ABSTRACT. Population persistence in isolated habitat fragments is investigated using integrodifference equations. The propensity of individual dispersers encountering the boundary of the patch to emigrate is defined by edge permeability. A dispersal model incorporating movement, settlement and edge permeability defines dispersal success as a function of a disperser's starting location. This dispersal model is used to generate dispersal kernels for integrodifference equation models, analysis of which gives a condition for population persistence in terms of edge permeability, patch size and average dispersal distance. An approximation reduces the spatial problem to a simple nonspatial model that can be easily analyzed.