增强型延迟反馈法控制低维混沌系统的解析研究

基于时间延迟反馈控制混沌系统的方法,提出一种增强型控制方案,并利用分析延迟系统产生Hopf分支条件的方法,给出这种方案控制低维连续自治混沌系统时,在达到控制目标的条件下,控制参数的一般解析关系.将这一方案和分析方法应用到两个混沌模型中,结果表明:采用修正的方案可以明显地改善控制混沌的效果和质量;解析分析的结果与实际数值计算的结果一致. 关键词： 延迟反馈 混沌控制 Hopf分支     

确定延迟反馈法控制混沌的可控性条件

基于数学上延迟（时滞）系统Hopf分支理论及分析方法，解析地确定出 用延迟反馈法可控制三阶自治混沌系统的一般条件.利用这种分析方法，着重从理论上 讨论了在控制意义下系统出现稳定周期解及由Hopf分支产生周期解的分支方向的判据.将这 些理论应用到三阶自治混沌系统的控制实例中，解析地得到使系统可控的参量区域.在该区 域内选择控制参量，通过数值模拟也得到控制系统从混沌到周期态的结果. 关键词： 延迟反馈 Hopf分支 控制混沌     

非线性自治系统频率特性及其利用

用数值模拟方法对三维非线性混沌系统进行了分析,发现衰减项参量的变化基本不影响系统的周期(指在同一周期内),并且系统基频与分频(基本周期与倍周期)之间还存在着近似的简单倍数关系.另外,还将Hopf分支理论中的实用分析方法应用到某些系统,解析地确定出系统开始出现稳定周期解(分岔)的临界位置、基本周期的近似值及分岔方向等有关特征量.进一步利用确定系统基本周期的方法以及基本周期和其他周期关系的规律,讨论了变量延迟反馈法控制混沌的两个实例 关键词： 自治系统 基本周期(频率) Hopf分支 混沌控制     

只有一个非线性项的超混沌系统

构造了只包含一个非线性项的四维超混沌系统,得到了系统的Lyapunov指数谱、周期轨道、拟周期轨道、混沌和超混沌吸引子.给出了此超混沌系统的电路实现原理图,利用EWB仿真得到了与数值仿真完全相符的动力学行为.同时给出了实现此超混沌系统同步的一种方法,并利用严格数学理论证明了该混沌同步方法.在同步过程中并未删除响应系统的非线性项,理论分析与仿真计算表明同步方法的有效性. 关键词： 四维超混沌系统 非线性项 Lyapunov指数谱     

广义同步延迟混沌系统的实验研究

利用电子线路实验设计并实现了一个二阶延迟混沌电路.在此基础上,利用线性变换方法,设计出广义同步混沌系统,用数学方法进行分析,理论上给出实现同步的解析条件,并在电路上加以实现.结合理论分析和实验结果,用数值方法进行了对照分析,进一步验证理论分析和实验电路设计的正确性和有效性. 关键词： 延迟混沌系统 广义同步 LC滤波器')" href="#">LC滤波器 电路实验     

广义同步延迟混沌系统的实验研究

利用电子线路实验设计并实现了一个二阶延迟混沌电路.在此基础上,利用线性变换方法,设计出广义同步混沌系统,用数学方法进行分析,理论上给出实现同步的解析条件,并在电路上加以实现.结合理论分析和实验结果,用数值方法进行了对照分析,进一步验证理论分析和实验电路设计的正确性和有效性.     

确定延迟反馈法控制低维混沌系统的控制条件

基于数学上分析延迟系统产生Hopf分支的条件及处理方法,针对用延迟反馈法控制低维混沌系统的情况,提出了确定其控制条件的一般解析方法.利用这种解析方法,可以从理论上得到控制参量间的函数关系.将该方法应用到一些实例中,得到了对实际控制混沌有重要指导意义的理论结果 关键词： 混沌 延迟反馈法 Hopf分支     

延迟变量反馈法控制离散混沌系统的电路实验

利用电子线路实验实现了一个具有混沌和超混沌特性的二维离散系统以及延迟变量反馈和它的增强型的方法用于混沌和超混沌的控制.实验结果，包括控制前实验电路出现的各种复杂行为和控制后从实验中观测到的许多被稳定住的周期状态，与理论分析和数值计算的结果几乎完全一致.也证实了增强型延迟变量反馈法控制混沌和超混沌的有效性.     

基础水平运动的弹簧摆的周期解与稳定性

针对基础水平运动的弹簧摆的非线性动力学响应进行研究,利用拉格朗日方程建立了系统的动力学方程.将离散傅里叶变换、谐波平衡法以及同伦延拓方法相结合,对系统的周期响应进行求解,避免了传统方法计算中使用泰勒展开引起的小振幅的限制,与数值计算结果的对比表明该求解方法具有较高的精确度.利用Floquet理论分析了周期响应的稳定性,给出了基础运动振幅和频率对系统周期响应的影响.研究发现:对应某些基础频率和振幅,系统的周期响应可能发生Hopf分岔;利用数值计算研究了Hopf分岔后系统响应随基础频率和振幅的变化,发现系统出现了倍周期运动、拟周期运动和混沌等复杂的动力学行为.研究表明系统进入混沌的主要路径是拟周期环面破裂和阵发性.     

非线性系统混沌化及广义同步的电路实验

利用定K型低通滤波器实现了非线性Rssler系统的混沌化,建立了延迟Rssler混沌系统实验电路.用主动-被动方法实现了单向耦合延迟Rssler混沌电路的广义混沌同步和广义反同步实验.     

Theoretical and experimental study of Chen chaotic system with notch filter feedback control

Since the past two decades, the time delay feedback control method has attracted more and more attention in chaos control studies because of its simplicity and efficiency compared with other chaos control schemes. Recently, it has been proposed to suppress low-dimensional chaos with the notch filter feedback control method, which can be implemented in a laser system. In this work, we have analytically determined the controllable conditions for notch filter feedback controlling of Chen chaotic system in terms of the Hopf bifurcation theory. The conditions for notch filter feedback controlled Chen chaoitc system having a stable limit cycle solution are given. Meanwhile, we also analysed the Hopf bifurcation direction, which is very important for parameter settings in notch filter feedback control applications. Finally, we apply the notch filter feedback control methods to the electronic circuit experiments and numerical simulations based on the theoretical analysis. The controlling results of notch filter feedback control method well prove the feasibility and reliability of the theoretical analysis.     

Dynamic analysis and synchronization control of an unusual chaotic system with exponential term and coexisting attractors

This paper reports a new four-dimensional chaotic system consisting of an exponential nonlinear term, two quadratic nonlinear terms and five linear terms. The system has only one equilibrium and performs stability, periodicity and chaos with the variation of the parameters. It losses its stability with the occurrence of Hopf bifurcation and goes into chaos via period-doubling bifurcation. One more interesting feature of the system is that it can generate multiple coexisting attractors for different initial conditions, such as two strange attractors with one limit cycle, one strange attractor with two limit cycles, etc. The dynamic properties of the system are presented by numerical simulation includes bifurcation diagrams, Lyapunov exponent spectrum and phase portraits. An electronic circuit is constructed to implement the chaotic attractor of the system. Based on the linear quadratic regulator (LQR) method, the synchronization control of the system is investigated.     

Nonlinear analysis of a maglev system with time-delayed feedback control

This paper undertakes a nonlinear analysis of a model for a maglev system with time-delayed feedback. Using linear analysis, we determine constraints on the feedback control gains and the time delay which ensure stability of the maglev system. We then show that a Hopf bifurcation occurs at the linear stability boundary. To gain insight into the periodic motion which arises from the Hopf bifurcation, we use the method of multiple scales on the nonlinear model. This analysis shows that for practical operating ranges, the maglev system undergoes both subcritical and supercritical bifurcations, which give rise to unstable and stable limit cycles respectively. Numerical simulations confirm the theoretical results and indicate that unstable limit cycles may coexist with the stable equilibrium state. This means that large enough perturbations may cause instability in the system even if the feedback gains are such that the linear theory predicts that the equilibrium state is stable.     

Coherence resonance and stochastic synchronization in a nonlinear circuit near a subcritical Hopf bifurcation

We analyze noise-induced phenomena in nonlinear dynamical systems near a subcritical Hopf bifurcation. We investigate qualitative changes of probability distributions (stochastic bifurcations), coherence resonance, and stochastic synchronization. These effects are studied in dynamical systems for which a subcritical Hopf bifurcation occurs. We perform analytical calculations, numerical simulations and experiments on an electronic circuit. For the generalized Van der Pol model we uncover the similarities between the behavior of a self-sustained oscillator characterized by a subcritical Hopf bifurcation and an excitable system. The analogy is manifested through coherence resonance and stochastic synchronization. In particular, we show both experimentally and numerically that stochastic oscillations that appear due to noise in a system with hard excitation, can be partially synchronized even outside the oscillatory regime of the deterministic system.     

多延时互耦合半导体激光器的实时混沌同步特性

针对双延时和三延时互耦合半导体激光器系统,研究了互耦合延时和互耦合强度对实时混沌同步质量的影响,提出了双延时互耦合系统中可将其中一个互耦合延时看作反馈延时的思想,揭示了多延时互耦合半导体激光器系统实时混沌同步条件和规律.研究结果表明,多延时互耦合系统中,某两条双向链路的互耦合延时比值为2,是实现高品质实时混沌同步的基本条件;增大互耦合强度,可以改善实时混沌同步品质,且在较低的等效耦合强度条件下,双延时互耦合系统较三延时互耦合系统更易于实现良好的实时混沌同步.     

利用线性可逆变换增强延迟反馈方法控制混沌的有效性

基于线性可逆变换方法，提出一种有效提高延迟反馈法控制混沌的方案.通过将系统的部分 状态变量在相应的子空间作变换，实现用单路反馈控制信号替代变换前多路信号对原系统的 控制作用，并且还从理论上确定出满足系统可控的条件.通过数值计算几个控制实例，其结 果很好地说明这种控制混沌的方案是有效和实用的. 关键词： 线性可逆变换 延迟反馈 控制混沌     

Dynamics of fractional-order sinusoidally forced simplified Lorenz system and its synchronization

In this paper, dynamical behaviors of the fractional-order sinusoidally forced simplified Lorenz are investigated by employing the time-domain solution algorithm of fractional-order calculus. The system parameters and the fractional derivative orders q are treated as bifurcation parameters. The range of the bifurcation parameters in which the system generates chaos is determined by bifurcation, phase portrait, and Poincaré section, and different bifurcation motions are visualized by virtue of a systematic numerical analysis. We find that the lowest order of this system to yield chaos is 3.903. Based on fractional-order stability theory, synchronization is achieved by using nonlinear feedback control method. Simulation results show the scheme is effective and a chaotic secure communication scheme is present based on this synchronization.