LOCAL STABILITY AND BIFURCATION IN A THREE—UNIT DELAYED NEURAL NETWORK

A system of three-unit networks with coupled cells is investigated.The general formula for bifurcation direction of Hopf bifurcation is calculated and the estimate formula of period of the periodic solution is given.     

Hopf bifurcation and chaos of financial system on condition of specific combination of parameters*

Exponential stability of the first order singular distributed parameter systems is discussed in the light of degenerate semi-group methods, which is described by the abstract developing equation in Hilbert space. The necessary and sufficient conditions concerning the exponential stability of the first order singular distributed parameter systems are given.     

GLOBAL STABILITY AND HOPF BIFURCATION OF AN SIS EPIDEMIC MODEL WITH TIME DELAYS

1 IntroductionFor epidemic model with delays, many people have done a lot of work and many valuableresults have been obtained. In SIS ePidemiologic models, susceptibles become infectious aftersufficieot contact with an infective and then become susceptible again after they have recoveredfrom the infection. SIS models with a time delay in the infectious class and a constan poWulation size were analyzed by Cooke and Yorke[1] and Greenberg and Hoppensteadt[2J. TheyfOund that aJl solutions a…     

信息物理融合系统中恶意软件传播与分岔控制策略

针对恶意软件在信息物理融合系统中传播机理难以描述的问题,利用非线性动力学理论构建其传播动力学模型,并基于稳定性理论和Hopf分岔定理对该模型的复杂动力学行为进行分析.为了控制恶意软件传播所引发的Hopf分岔,根据分岔控制理论设计了一类结合参数调节法与状态反馈法的混合分岔控制策略,并深入研究控制参数对Hopf分岔点位置及极限环幅值的影响.数值仿真结果表明所设计的混合分岔控制策略不仅能够提前或推迟Hopf分岔点,而且可以改变极限环幅值大小,使信息物理融合系统产生预期的动力学行为,实现控制目的,从而有效降低恶意软件的危害.     

基于采样数据模型的DC-DC变换器中分岔现象分析

DC-DC变换器中存在着丰富的非线性现象,分岔的出现是DC-DC变换器失稳的表现。为研究DC-DC变换器中的分岔现象,采用采样数据法建立DC-DC变换器的精确数学模型,给出对分岔现象进行仿真分析的公式,以Buck变换器为例,通过仿真和实验观察不同参数下分岔现象的出现,从而得出电路参数变化对DC-DC变换器稳定性的影响。     

一类比率依赖种群模型在常数收获下的分岔

利用微分方程定性理论以及规范型理论研究了一类具有常数收获项的生物模型.首先,考虑常数收获项对该模型非负平衡点的影响,讨论平衡点的稳定性情况.其次,选取常数收获项作为参数,给出系统存在鞍结点分岔、Hopf分岔以及极限环的充分条件.进一步地,考虑双参数分岔,给出系统存在余维2的Bogdanov-Takens分岔的充分条件.结果表明,由于添加了常数收获项,系统具有丰富的动力学行为.最后,通过数值仿真验证了所得结果的正确性.     

Singularly perturbed bifurcation subsystem and its application in power systems

The singularly perturbed bifurcation subsystem is described, and the test conditions of subsystem persistence are deduced. By use of fast and slow reduced subsystem model, the result does not require performing nonlinear transformation. Moreover, it is shown and proved that the persistence of the periodic orbits for Hopf bifurcation in the reduced model through center manifold. Van der Pol oscillator circuit is given to illustrate the persistence of bifurcation subsystems with the full dynamic system.     

Singularly perturbed bifurcation subsystem and its application in power systems

The singularly perturbed bifurcation subsystem is described,and the test conditions of subsystem persistence are deduced.By use of fast and slow reduced subsystem model,the result does not require performing nonlinear transformation.Moreover,it is shown and proved that the persistence of the periodic orbits for Hopf bifurcation in the reduced model through center manifold.Van der Pol oscillator circuit is given to illustrate the persistence of bifurcation subsystems with the full dynamic system.     

ON AN ELLIPTIC PROBLEM INVOLVING CRITICAL AND SUBLINEAR GROWTH

In this paper, the author considers an elliptic problem with critical and sub-linear growth. Some results about the multiplicity and uniqueness of the positive solutions are given by making use of variational method and bifurcation theory.     

新的单参数混沌振子网络的同步化区域的转迁

本文针对一个新发现的单参数混沌系统作为节点动力学的动力网络，在给定某一内连矩阵情况下，研究了随节点动力学参数的连续变化，复杂动力网络同步化区域的演化与切换. 我们把这种网络同步化区域随节点动力学参数发生变化的现象称为网络同步化区域的分岔或转迁. 结果发现，对于某些内连矩阵，同步化区域不产生分岔现象，表明网络同步状态的稳定性不会因节点动力学参数的变化而发生改变；而对于某些内连矩阵，随节点动力学参数的逐渐增大，同步化区域主要出现了下面几种分岔或转迁模式：（1）无界-空集型的，（2）空集-有界-无界-有界-无界型的，（3）空集-无界-空集-无界-空集-无界型的，（4）空集-有界-无界-有界界-无界型的. 在这些分岔模式中，同步化区域随动力学参数的增大最后大都演化成无界型的，与统一混沌系统为节点动力学的网络的同步化区域的分岔模式有着显著差异. 这些现象表明：同一类型的节点动力学，不同的内连矩阵，矩阵网络同步化区域的分岔模式是不一样的；同一内连矩阵，不同类型的节点动力学，网络的同步区域的分岔模式也存在很多差异；不同的分岔模式，网络同步状态的稳定性也是不一样，它势必影响网络的同步能力.     

DYNAMICAL BEHAVIORS OF A FOUR-DIMENSIONAL SYSTEM IN INFECTIOUS DISEASE

ＤＹＮＡＭＩＣＡＬＢＥＨＡＶＩＯＲＳＯＦＡＦＯＵＲ－ＤＩＭＥＮＳＩＯＮＡＬＳＹＳＴＥＭＩＮＩＮＦＥＣＴＩＯＵＳＤＩＳＥＡＳＥＬＩＮＹｉｐｉｎｇ（ＹｕｎｎａｎＩｎｓｔｉｔｕｔｅｏｆＡｐｐｌｉｅｄＭａｔｈｅｍａｔｉｃｓ，ＫｕｎｍｉｎｇＩｎｓｔｉｔｕｔｅｏ...     

Buck变换器仿真模型及分岔与混沌研究

对工作于电流连续模式下的电压控制型Buck变换器,利用仿真软件Matlab/Simulink,建立了一个对其非线性现象进行研究的仿真模型。根据其结构、电路参数及不同的工作条件,该模型可分别从时域与相图的角度对Buck变换器中的分岔与混沌进行分析。通过计算机仿真,观察到了以输入电压和输出电容作为分岔参数的混沌现象及系统输出特性,在V-I相图中观察到了系统由稳定到混沌的演化过程。所有仿真结果均与以往的理论分析相符,因而验证了该模型的合理性和可行性。具有重要意义的是该建模方法也适用于其它DC/DC变换器。     

EXISTENCE OF MULTIPLE SOLUTIONS AND BIFURCATIONFOR CRITICAL SEMILINEAR BIHARMONIC EQUATIONS

ＥＸＩＳＴＥＮＣＥＯＦＭＵＬＴＩＰＬＥＳＯＬＵＴＩＯＮＳＡＮＤＢＩＦＵＲＣＡＴＩＯＮＦＯＲＣＲＩＴＩＣＡＬＳＥＭＩＬＩＮＥＡＲＢＩＨＡＲＭＯＮＩＣＥＱＵＡＴＩＯＮＳＥＸＩＳＴＥＮＣＥＯＦＭＵＬＴＩＰＬＥＳＯＬＵＴＩＯＮＳＡＮＤＢＩＦＵＲＣＡＴＩＯＮＦ...     

阶段结构广义生物经济模型的分岔及控制

利用微分代数方程理论研究了一类广义生物经济模型.首先,研究参数临界状态下,该模型平衡点的稳定性情况,并进一步给出系统存在跨临界分岔和奇异诱导分岔的充分条件.其次,设计状态反馈控制器,通过控制捕获努力量,消除该系统中存在的奇异诱导分岔及脉冲行为,抑制种群变化,使系统趋于稳定.最后,通过数值仿真说明控制器的有效性.     

Hopf bifurcation analysis and bifurcation control of a lorenz-like system北大核心CSCD

Hopf bifurcation behavior and bifurcation control of a new Lorenz-like system are studied in this paper. Firstly, Hopf bifurcation type is determined by bifurcation stability norm. Then the linear controller and the non-linear controller are applied to control the original system respectively. In the section of linear control, the effect of linear parameter on the position of Hopf bifurcation is discussed by Routh-Hurwitz criterion; In the section of non-linear control, the Hopf bifurcation Normal Form of controlled system is obtained by using direct Normal Form method, and the effects of nonlinear parameter on amplitude of limit cycle and Hopf bifurcation type are discussed by coefficient of Normal Form. Discussions show that if non-linear parameter satisfies certain condition, bifurcation type of original system will be changed, and the periodic solution amplitude will increase with the parameter increasing. ©, 2015, The Journal Agency of Complex Systems and Complexity Science. All right reserved.     

一个新自治混沌系统的动力学分析

提出了一个新的三维连续自治混沌系统.该系统含有4个控制参数,2个不同的非线性乘积项,并且方程式中含有指数形式的非线性项e(dz).利用理论推导、数值仿真对系统的基本动力学特性进行了分析,通过分岔图、Lyapunov指数图、Poincaré映射和相图等分析了控制参数变化时,系统动力学行为的变化.结果表明该新系统不但和Lorenz系统族有类似的性质,而且又呈现不同的非线性特征.     

混沌粒子群优化及其分析

通过分析了经典的粒子群优化中单个粒子模型,发现其具有混沌Hopfield神经网络的特点.提出了一种新的粒子群优化模型,该模型不像以往的粒子群算法那样包含随机参数,而是一个确定性的混沌Hopfield神经网络群,其搜索轨道展现了从混沌到周期分岔再到汇的逆周期分岔演化过程.初始混沌式搜索模式展宽了搜索范围,逆周期分岔演化过程决定了搜索的稳定性和收敛性.另外,理论上给出了新的粒子群优化的收敛性结论.最后,通过数值仿真给出了与经典的粒子群优化结果的不同点,并且说明了混沌粒子群优化的有效性.     

GLOBAL AND LOCAL BIFURCATION IN PERTURBATIONS OF NON－SYMMETRY AND SYMMETRY OF HAMILTONIAN SYSTEM

ＧＬＯＢＡＬＡＮＤＬＯＣＡＬＢＩＦＵＲＣＡＴＩＯＮＩＮＰＥＲＴＵＲＢＡＴＩＯＮＳＯＦＮＯＮ－ＳＹＭＭＥＴＲＹＡＮＤＳＹＭＭＥＴＲＹＯＦＨＡＭＩＬＴＯＮＩＡＮＳＹＳＴＥＭ￥ＬＩＵＺｈｅｎｇｒｏｎｇ（ＩｎｓｔｉｔｕｔｅｏｆＡｐｐｌｉｅｄＭａｔｈｅｍａｔｉ...     

异性人口的HIV/AIDS流行病模型的分岔

在异性人口中HIV的传播对HIV／AIDS流行病产生了极大的影响，这一事实早已被人们所认识。本文通过异性人口的HIV／AIDS流行病的非对称模型的分岔问题的讨论，给出了这个模型的实际定义与解释，并运用中心流行定理及其计算方法得到，在这个模型的疾病消除平衡点处出现静态分岔，且它的分岔的余维数等于一。由此得到这个系统是结构不稳定的，因此社会环境的改变对疾病控制也起着重要作用。     

EXISTENCE AND ANALYTICAL APPROXIMATIONS OF LIMIT CYCLES IN A THREE-DIMENSIONAL NONLINEAR AUTONOMOUS FEEDBACK CONTROL SYSTEM

This paper is concerned with the existence and the analytical approximations of limit cycles in a three-dimensional nonlinear autonomous feedback control system. Based on three-dimensional Hopf bifurcation theorem, the existence of limit cycles is first proved. Then the homotopy analysis method （HAM） is applied to obtain the analytical approximations of the limit cycle and its frequency. In deriving the higher-order approximations, the authors utilized the idea of a perturbation procedure proposed for limit cycles＇ approximation in van der Pol equation. By comparing with the numerical integration solutions, it is shown that the accuracy of the analytical results obtained in this paper is very high, even when the amplitude of the limit cycle is large.