n维糖酵解模型非常数稳态解的模式生成

研究了一类带Neumann边界条件的n维糖酵解模型.首先,以扩散系数d1为分歧参数,运用局部分歧理论分析了该模型非常数稳态解的局部结构.其次,利用全局分歧理论和LeraySchauder度理论讨论了非常数稳态解的全局存在性.最后,借助数值模拟证实了所得结论.分析结果表明n维糖酵解模型的空间模式可以生成.     

一类具有修正的Leslie-Gower项的捕食-食饵模型的正解

主要研究一类具有修正的Leslie-Gower型的捕食-食饵模型正解的动力学行为.首先,利用不动点指数理论给出了正解存在的充分条件;其次,讨论了当m充分大时模型正解的唯一性和稳定性;最后,以a为分歧参数,利用局部分歧理论研究了正解的分支结构,以及在适当条件下正解的多解性和局部分歧解的稳定性.结果 表明:在适当条件下两物...     

一类捕食——食饵模型正平衡解的整体分歧

讨论了一类改进的Leslie-Gower和Holling-Type Ⅱ型捕食-食饵模型对应的平衡态系统正解的结构.以捕食者的出生率b为分歧参数,利用局部分歧理论和整体分歧理论,得到了此平衡态系统正解的存在性与参数b的关系,即当b适当大时,该平衡态系统具有共存正解.     

一类带Michaelis-Menten收获项的Holling-Ⅳ型捕食-食饵模型的定性分析

本文对一类带Michaelis-Menten收获项的Holling-Ⅳ型捕食-食饵模型进行了定性分析.首先,利用极值原理和线性稳定性理论,得到了平衡态方程解的先验估计和正常数解的局部渐近稳定性;然后,借助分歧理论,给出了以d2为分歧参数,平衡态方程在正常数解U_1处的局部分歧,证明了在一定条件下,(d_2~j,U_1)处产生的局部分歧可以延拓成全局分歧.     

带Ivlev反应项的捕食模型的全局分歧

在Dirichlet边界条件下研究一类带Ivlev反应项的捕食模型.利用谱分析和分歧理论的方法,证明了发自半平凡解的局部分歧正解的存在性,同时运用线性特征值扰动理论给出局部分歧解的稳定性.最后将局部分歧延拓为全局分歧,从而得到正解存在的充分条件.     

一类具有自动催化作用和饱和定律的双分子模型的图灵不稳定性和霍普夫分歧

通过分析线性化系统的特征值并利用分歧定理,研究了一类具有自动催化作用和饱和定律的双分子模型的图灵不稳定性和霍普夫分歧,并利用数值模拟的方法证明和解释了理论结果.     

米粒组织的分歧与跃迁

运用线性全连续场的谱理论及跃迁理论讨论了太阳米粒组织的分歧和跃迁,并且从数学上证明了米粒组织的存在性.同时在一定的假设条件下了,得到了特征值,特征向量和分歧解的表达式.最后根据模型给出了米粒组织直径的估计,同时验证了该估计与实际数据基本相符.     

一类Chemostat捕食模型正周期解的存在性

讨论了一类Chemostat捕食模型在一定条件下正周期解的存在性问题.运用周期抛物型算子理论、Schauder估计和分歧理论得到了该模型正周期解存在的充分必要条件.     

一类食饵-捕食生物模型的动态分歧

本文运用线性全连续场的谱理论及跃迁理论讨论了一类食饵-捕食生物模型的动态分歧,在一定条件下得到了跃迁类型的判据,并判断了跃迁的类型,同时也给出了分歧解的表达式,最后对获得的结果做了必要的解释.     

一类具有强Allee效应和Beddington-DeAngelis响应的捕食模型的动力学分析

研究了一类食饵具有强Allee效应和Beddington-DeAngelis响应函数的修正型Leslie-Gower捕食-食饵模型的动力学行为.结合特征值理论和线性化分析得到平衡解的稳定性.利用Poincaré-Andronov-Hopf分歧定理得到Hopf分歧的存在性.借助Matlab数值模拟展示丰富的空间动力学性质.     

The Coexistence States of a Predator-Prey Model with Nonmonotonic Functional Response and Diffusion

In this paper, a predator-prey model with nonmonotonic functional response is concerned. Using spectrum analysis and bifurcation theory, the bifurcating solution and its stability of the model are investigated. We discuss the bifurcation solution which emanates from the semi-trivial solution by taking the death rate as a bifurcation parameter. Furthermore, by fixed point’s index theory, the result of existence or nonexistence of positive steady states of the model is also obtained.     

Crowding effects on coexistence solutions in the unstirred chemostat

This paper deals with the unstirred chemostat model with crowding effects. The introduction of crowding effects makes the conservation law invalid, and the equations cannot be combined to eliminate one of the variables. Consequently, the usual reduction of the system to a competitive system of one order lower is lost. Thus the system with predation and competition is non-monotone, and the single population model cannot be reduced to a scalar system. First, the uniqueness and asymptotic behaviors of the semi-trivial solutions are established. Second, the existence and structure of coexistence solutions are given by the degree theory and bifurcation theory. It turns out that the positive bifurcation branch connects one semi-trivial solution branch with another. Finally, the stability and asymptotic behaviors of coexistence solutions are discussed in some cases. It is shown that crowding effects are sufficiently effective in the occurrence of coexisting, and overcrowding of a species has an inhibiting effect on itself.     

Bifurcations analysis and tracking control of an epidemic model with nonlinear incidence rate

In this paper, a discrete epidemic model with nonlinear incidence rate obtained by the forward Euler method is investigated. The conditions for existence of codimension-1 bifurcations (fold bifurcation, flip bifurcation and Neimark-Sacker bifurcation) are derived by using the center manifold theorem and bifurcation theory. Furthermore, the condition for the occurrence of codimension-2 bifurcation (fold-flip bifurcation) is presented. In order to eliminate the chaos or Neimark-Sacker bifurcation of the discrete epidemic model, a tracking controller is designed. The number of the infectives tends to zero when the number of iterations is gradually increasing, that is, the disease disappears gradually. Finally, numerical simulations not only illustrate the validity of the proposed results, but also display the interesting and complex dynamical behaviors.     

具饱和传染率的脉冲免疫接种SIRS模型

研究了具饱和传染率的脉冲免疫接种SIRS模型的一致持续生存和周期解,得到了无病周期解全局渐近稳定的充分条件和系统一致持续生存的充分条件,并应用分支理论得到了正周期解存在的分支参数.     

Bifurcation theory of functional differential equations: A survey

In this paper we survey the topic of bifurcation theory of functionaldifferential equations. We begin with a brief discussion of the position of bifurcationand functional differential equations in dynamical systems. We followwith a survey of the state of the art on the bifurcation theory of functionaldifferential equations, including results on Hopf bifurcation, center manifoldtheory, normal form theory, Lyapunov-Schmidt reduction, and degree theory.     

Backward bifurcation in simple SIS model

We describe and analyze a simple SIS model with treatment. In particular, we give a completely qualitative analysis by means of the theory of asymptotically autonomous system. It is found that a backward bifurcation occurs if the adequate contact rate or the capacity is small. It is also found that there exists bistable endemic equilibria. In the case of disease-induced death, it is shown that the backward bifurcation also occurs. Moreover, there is no limit cycle under some conditions, and the subcritical Hopf bifurcation occurs under another conditions. Supported by the National Natural Science Foundation of China (No. 10571143, 30770555)     

Hopf-zero bifurcation of a delayed predator-prey model with dormancy of predators

In this paper, We investigate Hopf-zero bifurcation with codimension 2 in a delayed predator-prey model with dormancy of predators. First we prove the specific existence condition of the coexistence equilibrium. Then we take the mortality rate and time delay as two bifurcation parameters to find the occurrence condition of Hopf-zero bifurcation in this model. Furthermore, using the Faria and Magalhases normal form method and the center manifold theory, we obtain the third order degenerate normal form with two original parameters. Finally, through theoretical analysis and numerical simulations, we give a bifurcation set and a phase diagram to show the specific relations between the normal form and the original system, and explain the coexistence phenomena of several locally stable states, such as the coexistence of multi-periodic orbits, as well as the coexistence of a locally stable equilibrium and a locally stable periodic orbit.     

Global bifurcation and stability of steady states for a bacterial colony model with density-suppressed motility

We investigate the structure and stability of the steady states for a bacterial colony model with density-suppressed motility. We treat the growth rate of bacteria as a bifurcation parameter to explore the local and global structure of the steady states. Relying on asymptotic analysis and the theory of Fredholm solvability, we derive the second-order approximate expression of the steady states. We analytically establish the stability criterion of the bifurcation solutions, and show that sufficiently large growth rate of bacteria leads to a stable uniform steady state. While the growth rate of bacteria is less than some certain value, there is pattern formation with the admissible wave mode. All the analytical results are corroborated by numerical simulations from different stages.     

Mechanism of producing a saddle-node bifurcation with the coalescence of two unstable periodic orbits

A saddle-node bifurcation with the coalescence of a stable periodic orbit and an unstable periodic orbit is a common phenomenon in nonlinear systems. This study investigates the mechanism of producing another saddle-node bifurcation with the coalescence of two unstable periodic orbits. The saddle-node bifurcation results from a codimension-two bifurcation that a period doubling bifurcation line tangentially intersects a saddle-node bifurcation line in a parameter plane. Based on the bifurcation theory, the saddle-node bifurcation with the coalescence of two unstable periodic orbits is studied using the codimension-two bifurcation.