具有饱和与竞争项的捕食系统的全局分歧及稳定性

利用比较原理,分歧理论,特征值线性扰动理论,主要研究了一类具有饱和与竞争反应项的捕食-食饵系统在Dirichlet边界条件下的平衡态分歧解.首先给出了一个先验估计和局部分歧解存在的充分条件.然后对局部分歧解进行了全局延拓,得到了该系统平衡态的全局分歧解及其走向.最后讨论了局部分歧解的稳定性.     

一类分数阶微分方程积分边值问题正解的分歧性

利用分歧方法和拓扑度理论,研究了一类带参数的分数阶微分方程积分边值问题正解的存在性.根据格林函数的性质,得到了系统正解的存在的若干充分条件.最后,通过数值例子验证了所得结果的有效性.     

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.     

一类核反应堆数学模型正解的全局分歧北大核心CSCD

本文研究一类源于核反应堆的数学模型正解的存在性.该模型旨在描述与快中子流密度、反应堆温度紧密相关的核反应过程.本文主要讨论反应堆与外界有热交换的情形.从数学的角度来看,模型自身的非合作特性导致对正解存在性及相关性质的研究较为困难,适用于研究合作系统的比较原理等方法将不再有效.运用分歧理论,我们获得了该模型存在正解的充分必要条件,建立了正解的全局分歧结果,同时对正解的渐近行为进行了仔细分析.所得结果丰富并补充了核反应堆数学模型的相关理论.     

一类具有扩散的捕食-食饵模型正解的存在性和惟一性

考虑了一类带Beddington-DeAngelis反应项的捕食-食饵模型正解的存在性和惟一性. 首先利用分歧理论给出正解存在的充分条件, 并刻画了整体分歧的结构. 然后利用特征值变分原理将所给的条件简化, 从而得到正解存在的更为简单更好计算的充分条件和必要条件. 最后利用隐函数定理和广义极大值原理在一维情况下给出了正解的存在惟一性.     

一类带非单调转化率的捕食-食饵模型的全局分歧

主要研究了一类带非单调转化率的捕食-食饵模型,分别以生长率a和b为分歧参数,运用度理论和分歧理论讨论了这类模型在齐次第一边界条件下全局分歧结构．     

计算立方体上Henon方程多个正解的分歧方法

本文首先应用分歧方法给出计算立方体上Henon方程边值问题D₄(3)对称正解的三种算法, 然后以Henon方程中的参数r为分歧参数, 在D₄(3)对称正解解枝上 用扩张系统方法求出对称破缺分歧点, 进而用解枝转接方法计算出其它具有不同对称性质的正解.     

计算圆域上p-Henon方程边值问题多个正解的分歧方法

首先应用分歧方法给出计算p-Henon方程边值问题O(2)对称正解的算法,然后以p-Henon方程中的参数l为分歧参数,在O(2)对称正解解枝上用扩张系统方法求出对称破缺分歧点,进而用解枝转接方法计算出其它具有不同对称性质的正解．     

计算Henon方程多个正解的分歧方法

首先应用分歧方法给出计算Henon方程边值问题D₄对称正解的3种算法, 然后以Henon方程中的参数r为分歧参数, 在D₄对称正解解枝上用扩张系统方法求出对称破缺分歧点, 进而用解枝转接方法计算出其他具有不同对称性质的正解.     

奇异三阶积分边值问题正解的全局分歧

研究带Riemann-Stieltjes积分边值条件的奇异三阶积分边值问题正解的全局分歧结构.首先,利用相关文献,获得了此类问题的格林函数并推证其满足的性质,同时可获得此类问题等价于一个全连续算子方程;其次,在满足所给的条件时,利用Krein-Rutmann定理建立了此类问题对应的线性问题存在简单的主特征值;最后,当非线性项在零和无穷远处满足非渐进线性增长条件、参数满足不同范围的值时,利用Dancer全局分歧定理、Zeidler全局分歧定理和序列集取极限的方法,建立了此类问题正解的全局结构,进而获得了正解的存在性.     

Bifurcation of an eco-epidemiological model with a nonlinear incidence rate

A predator-prey system with disease in the prey is considered. Assume that the incidence rate is nonlinear, we analyse the boundedness of solutions and local stability of equilibria, by using bifurcation methods and techniques, we study Bogdanov-Takens bifurcation near a boundary equilibrium, and obtain a saddle-node bifurcation curve, a Hopf bifurcation curve and a homoclinic bifurcation curve. The Hopf bifurcation and generalized Hopf bifurcation near the positive equilibrium is analyzed, one or two limit cycles is also discussed.     

The existence and stability of steady states for a prey-predator system with cross diffusion of quasilinear fractional type

This paper is concerned with the existence and stability of steady states for a prey-predator system with cross diffusion of quasilineax fractional type. We obtain a sufficient condition for the existence of positive steady state solutions by applying bifurcation theory and a detailed priori estimate. In virtue of the principle of exchange of stability, we prove the stability of local bifurcating solutions near the bifurcation point.     

The Existence and Stability of Steady States for a Prey-predator System with Cross Difusion of Quasilinear Fractional Type

This paper is concerned with the existence and stability of steady states for a prey-predator system with cross difusion of quasilinear fractional type.We obtain a sufcient condition for the existence of positive steady state solutions by applying bifurcation theory and a detailed priori estimate.In virtue of the principle of exchange of stability,we prove the stability of local bifurcating solutions near the bifurcation point.     

Spatial resonance and Turing–Hopf bifurcations in the Gierer–Meinhardt model

Gierer–Meinhardt system as a molecularly plausible model has been proposed to formalize the observation for pattern formation. In this paper, the Gierer–Meinhardt model without the saturating term is considered. By the linear stability analysis, we not only give out the conditions ensuring the stability and Turing instability of the positive equilibrium but also find the parameter values where possible Turing–Hopf and spatial resonance bifurcation can occur. Then we develop the general algorithm for the calculations of normal form associated with codimension-2 spatial resonance bifurcation to better understand the dynamics neighboring of the bifurcating point. The spatial resonance bifurcation reveals the interaction of two steady state solutions with different modes. Numerical simulations are employed to illustrate the theoretical results for both the Turing–Hopf bifurcation and spatial resonance bifurcation. Some expected solutions including stable spatially inhomogeneous periodic solutions and coexisting stable spatially steady state solutions evolve from Turing–Hopf bifurcation and spatial resonance bifurcation respectively.     

Stability and Hopf bifurcation in a delayed competition system

In this paper, Hopf bifurcation for two-species Lotka–Volterra competition systems with delay dependence is investigated. By choosing the delay as a bifurcation parameter, we prove that the system is stable over a range of the delay and beyond that it is unstable in the limit cycle form, i.e., there are periodic solutions bifurcating out from the positive equilibrium. Our results show that a stable competition system can be destabilized by the introduction of a maturation delay parameter. Further, an explicit algorithm for determining the direction of the Hopf bifurcation and the stability of the bifurcating periodic solutions is derived by using the theory of normal forms and center manifolds, and numerical simulations supporting the theoretical analysis are also given.     

时滞偏害系统的稳定性和分歧分析

本文讨论了具离散和分布时滞的偏害系统.以时滞作为分歧参数,通过分析原系统在正平衡点处线性化系统的特征方程,获得了正平衡点渐近稳定以及在它周围分歧出周期解的条件.另外,通过使用规范形和中心流形定理,我们获得了Hopf分歧的方向和分歧周期解稳定性的显式算法.最后,数值模拟支持了我们的理论分析.     

具有饱和项的互惠系统的分歧与稳定性

运用谱分析和分歧理论的方法,在齐次Dirichlet边界条件下,对具有饱和项的互惠系统的非负定态解的分歧及其稳定性进行研究.一方面,分别以生长率作为分歧参数,讨论了发自半平凡解的分歧;另一方面,以两物种的生长率作为分歧参数,利用Liapunov-Schmidt过程,研究了在二重特征值处的分歧;同时判定了这些分歧解的稳定性.     

一类具有保护区域的Leslie-Gower捕食-食饵模型的分歧分析

研究了一类Neumann边界条件下带有保护区域的Leslie-Gower捕食-食饵模型,分析稳态系统从半平凡解处发生分歧的条件,得到了分歧方向及分歧值的唯一性,得到了在确定参数范围内,从半平凡解出发的分支解曲线的稳定性.     

具有捕食者相互残杀项时滞系统的Hopf分支

研究了具有捕食者相互残杀项的时滞系统的Hopf分支,通过选择时滞作为一个分支参数,研究了正平衡点的稳定性和正周期解的Hopf分支.而且通过应用规范型和中心流形的理论,得出了确定分支方向的明确的算法.     

具有扩散的广义Brusselator系统的Hopf分歧

在齐次Neumann边界条件下,考虑广义Brusselator系统．首先讨论常微分系统Hopf分歧的存在性,得到渐近稳定的周期解．其次讨论具有扩散的偏微分系统,在扩散系数满足一定的条件下,得到超临界的Hopf分歧,并利用规范形理论和中心流形定理给出空间齐次周期解的渐近稳定性．最后,借助Matlab软件进行数值模拟,证明了定理的结论．同时,正平衡态解和空间非齐次周期解的描绘补充了理论分析结果．