Control of Julia Sets in Generalized Alternated System

In this paper, we first introduce the generalized alternated system. The definition of the Julia set in the generalized alternated system is given, which is called a generalized alternated Julia set. Then, we achieve the control of generalized alternated Julia sets by applying the classic control methods, which are gradient control and optimal control. In addition, the synchronization between two different generalized alternated Julia sets is implemented using gradient control and optimal control. The simulations illustrate the effectiveness and correctness of these two control methods, and the results are displayed in 2D computer graphics.     

一类广义Logistic映射的分形特征与同步

本文讨论了一类二维广义Logistic实映射的Julia集和Mandelbrot集.首先采用盒维数计算法,计算了实映射Julia集的分形维数,并引入一种线性反馈控制的方法,对实映射的Julia集进行了控制.其次引入不同系统间Julia集同步的概念,通过非线性耦合控制的方法,对具有不同参数两个实映射的Julia集进行了同步.最后通过引入实参数的方法构造了实映射的Mandelbrot集,并通过梯度控制法实现了具有不同参数的两个实映射Mandelbrot集的同步.仿真结果表明了控制和同步方法的有效性.     

Julia集的广义同步

研究了两个不同的Julia集耦合实现广义同步的问题. 不同于以往对Julia集的研究仅限于对一个独立的Julia集的性质, 制图等方面的讨论, 本文提出了两个不同的Julia集广义同步的思想, 并以经典的复二次多项式系统z_n+1 = z²_n+c为例, 分别采用线性和非线性耦合的方法对该系统不同参数的Julia集进行了广义同步. 仿真结果表明了方法的有效性.     

Optimal Control and Synchronization of Alternated Julia Sets

In this paper, spatial‐alternated Julia sets are discussed, which are obtained by alternating the spatial‐alternated system, and plane‐alternated Julia sets are discussed, which are obtained by alternating the plane‐alternated system. The control of spatial‐alternated Julia sets and plane‐alternated Julia sets is achieved via the optimal control. Moreover, the synchronization of two different plane‐alternated Julia sets is implemented via the optimal control. The simulations illustrate the effectiveness of the control method.     

不同空间Julia集的非线性广义同步

基于利用线性耦合实现空间Julia集线性广义同步的研究成果,本文通过应用非线性反馈控制和引入变量变换的方法解决了空间Julia集的非线性广义同步问题.首先基于变量变换,得到误差空间Julia系统,为了镇定该系统使其实现非线性广义同步,给出了确定的非线性函数关系式.另外,根据空间Julia集的稳定区域,解析地确定了实现非线性广义同步的耦合强度的稳定域.然后,给出了稳定的复不动平面与空间Julia集的同步的关系.最后,用一个例子验证了该解析方法是可行的.     

Fractal analysis and control in the predator–prey model

The two-dimensional predator–prey Lotka–Volterra model is discussed from the point of fractal theory. Julia set of the discrete version of the model is introduced. Then, the linear feedback control is taken to control the Julia set. By controlling the Julia set, the attractive domain of the attractive fixed point is controlled indirectly. To associate two different Julia sets of the model with different parameters, nonlinear coupling items are designed to make one Julia set change to be another. The simulations illustrate the efficacy of these methods.     

Fractal Dimension and Synchronization of the Controlled Julia Sets of a Reaction–Diffusion System

This paper is concerned with the fractal dynamics of a reaction–diffusion system, – the forced Brusselator model. The Julia set of the discrete version of the model is established. Then, the control of the Julia set is realized by combining the parameter perturbation control method and feedback control method. The box‐counting dimensions of the Julia sets of the controlled system for different control parameters are computed, which is used to describe the complexity and irregularity of the Julia sets. Finally, nonlinear coupling items are designed to make one Julia change to be another. The simulations illustrate the efficacy of these methods.     

Pinning Cluster Synchronization of Coupled Nonidentical Harmonic Oscillators Under Directed Topology

This paper addresses cluster synchronization of coupled harmonic oscillators over directed fixed and switching topologies, where uncoupled harmonic oscillators in the same cluster have the identical node dynamics, while any pair of nodes in different clusters are essentially distinguishing according to their local dynamics. A pinning control protocol is proposed for such coupled harmonic oscillators system, and then some graphic topology conditions easy to verify are established for cluster synchronization. The main contributions of the present investigation include: (i) cluster synchronization problem of coupled nonidentical harmonic oscillators is addressed over directed topology; (ii) desynchronizing motion of harmonic oscillators from different clusters doesn't depend on negative coupling weights but leader of every cluster; (iii) this paper deals with what kind of harmonic oscillators ought to be pinned in order to reach cluster synchronization. Finally, numerical examples and simulations demonstrate the obtained theoretical results.     

基于直流电机系统的广义同步混沌化

本文对非同构系统的混沌状态同步问题进行了讨论,并对单变量单向及双向耦合和多变量耦合对各自系统动力学行为产生的影响进行了对比分析.基于广义同步混沌化的驱动控制原理,利用经典的Lorenz系统产生混沌信号去驱动永磁直流电机,使电机转速工作在混沌状态,并得到了同步控制器的解析表达式.最后,进行系统数值仿真,验证了同步控制的有效性.     

Julia分形

近年来分形理论和它的构造方法受到极大关注.Julia集是使用非线性复映射f(z)=zm c为迭代函数生成的一类著名分形,而逃逸时间算法是生成Julia集最常用的算法.本文在给出逃逸时间算法的算法步骤之后,针对迭代函数fmc(z)=zm c中参数m,c变化的不同情况,给出了Julia集的实验图例,并分析了二次表达式的常规Julia集(m=2)和高阶的广义Julia集(m＞2)的一些特点.     

Pinning‐controlled synchronization of hybrid‐coupled complex dynamical networks with mixed time‐delays

This paper investigates the pinning‐controlled synchronization of a general complex dynamical network with hybrid coupling, which includes constant coupling, discrete‐delay coupling and distributed‐delay coupling. Furthermore, the network can be composed of coupled identical nonlinear oscillators with or without internal time‐delay. To be more consistent with the realistic networks, the internal time‐delay, the discrete time‐delay and the distributed time‐delay can be different from each other, the inner coupling matrices are not necessarily to be diagonal, and the coupling configuration matrices are not required to be symmetric or irreducible. Under some sufficient conditions, it is shown that a hybrid‐coupled complex network with or without internal time‐delay can be asymptotically pinned to a homogenous trajectory by applying adaptive control actions to a small fraction of network nodes. In particular, the paper addresses what kind of nodes should be pinned and how many nodes are needed to be pinned to achieve synchronization in a hybrid‐coupled network with fixed coupling matrices and strengths. Numerical examples are given to verify the theoretical analysis. Copyright © 2011 John Wiley & Sons, Ltd.     

Some synchronization criteria for bidirectionally-coupled chaotic systems

1IntroductionChaos synchronization,as a very important topic in thenonlinear science ,has been developed extensivelyinthelastfew years [1,2] .A wide variety of approaches [1 ~9]have been proposed for the synchronization of chaoticsystems which include linear and nonlinear feedback,adaptive control ,etc . Most of the methods mentionedabove synchronize two coupled identical chaotic systems .Accordingto the condition of coupling signal ,they can beclassified into bidirectional [3 ~5] and unidirec…     

Some synchronization criteria for bidirectionally-coupled chaotic systems

Based on the stability theory of linear time-varying continuous system,this paper investigates the synchronization of two linear bidirectionally-coupled systems.Sufficient conditions for asymptotic synchronization are obtained for general chaotic system with bidirectional coupling via linear error feedback.Since the trajectory of chaotic system is continuous and bounded,one can choose suitable coupled parameters to satisfy the proposed criterion.The criterion can also be applied to the global synchronization for chaotic systems with linear unidirectional coupling.The chaotic Chen system and the generalized Lorenz-like system are taken as examples,the simulations verify the effectiveness of the proposed method.     

基于三维多项式映射的广义Julia集表示与绘制

研究了基于三维多项式映射的三维广义Julia集表示方法.从理论上分析并证明了三维多项式映射满足等变的条件,精确地给出了关于正四面体群和正八面体群具有旋转不变对称性的两类三维等变映射的具体公式,在此基础上讨论并证明了三维多项式映射的广义Julia集所具有的性质.提出了基于逃选距离色彩调配的光线跟踪体绘制算法,对给定三维空间中属于Julia集的离散点根据其逃逸距离赋予颜色和不透明度,并采用光线跟踪法进行体绘制.实验结果表明,利用三维多项式映射来构造三维Julia集,不仅可以根据映射的性质预知Julia集的总体结构特征,并且能够通过调控映射的参数来获得多种具有不同旋转对称结构的Julia集,因而有效地克服了现有三维分形集生成方法所构造的分形集包含信息量少、形状结构单一和分形形状无法预测等缺陷.进一步地,三维多项式映射可以应用于其他三维分形的构造,从而为三维分形的生成提供一个新的有效途径.     

Decentralized adaptive synchronization of an uncertain complex delayed dynamical network

In this paper, we investigate the locally and globally adaptive synchronization problem for an uncertain complex dynamical network with time-varying coupling delays based on the decentralized control. The coupling terms here are bounded by high-order polynomials with known gains that are ubiquitous in a large class of complex dynamical networks. We generalize the usual technology of searching for an appropriate coordinates transformation to change the network dynamics into a series of decoupled lower-dimensional systems. Several adaptive synchronization criteria are derived by constructing the Lyapunov-Krasovskii functional and Barbalat lemma, and the proposed criteria are simple in form and convenient for the practical engineering design. Numerical simulations illustrated by a nearest-neighbor coupling network verify the effectiveness of the proposed synchronization scheme.     

欺骗攻击环境下具有执行器故障的跳变耦合 信息物理系统的同步控制

针对一类离散Markov跳变耦合信息物理系统(CPS)的同步控制问题,在考虑系统参数跳变、耦合参数跳变、控制信息不完全和人为攻击的情况下,设计同步控制器实现CPS的同步.首先,给出具有随机欺骗攻击和执行器故障的Markov跳变耦合CPS模型.其次,基于矩阵Kronecker积,得到同步误差系统,将CPS的同步控制问题转化为同步误差系统的稳定性分析问题.再次,通过构造合适的Lyapunov-Krasovskii泛函,并利用Lyapunov稳定性理论和线性矩阵不等式方法得到使同步误差系统稳定的充分条件,在此基础上,设计同步控制器实现对Markov跳变耦合CPS的同步控制.最后,通过数值仿真例子说明该同步控制器设计方法的有效性.     

不同节点动态的复杂网络外部同步牵制控制

研究节点动态不同的两个复杂网络的外部同步问题。运用牵制控制方法,网络模型选取节点输出线性耦合模型,基于输出控制思想,设计结构简单的牵制控制器,对响应网络中的部分节点施加输出反馈控制,使得两个复杂动态网络达到外部同步,即实现响应网络与驱动网络的渐近同步。根据李雅普诺夫稳定性理论,推出相应的同步准则,得到控制器参数选择条件。仿真时,驱动网络和响应网络分别选取Lorenz系统和Lu系统,对全局耦合网络和最近邻耦合网络两个典型网络拓扑进行仿真,验证了所提方法的有效性。     

随机干扰下拓扑时变Kuramoto网络事件触发固定时间同步

本文针对一类网络拓扑时变且耦合通道存在随机干扰的Kuramoto型振子网络的同步问题, 设计了事件触 发机制下的固定时间控制算法. 针对耦合网络的拓扑在切换中保持连通的假设, 给出了一种具有多层结构的事件 触发分布式控制策略, 并能够抵消随机干扰对同步性能带来的负面影响. 利用随机Lyapunov稳定理论和固定时间稳 定性理论给出了达到实际固定时间相位同步的控制参数条件和同步调节时间的上界. 另外, 证明了所使用的事件 触发机制在引入双曲正切函数之后不会产生Zeno现象, 并给出了触发间隔的下界. 同时, 在推论中给出了本文提出 的控制方法也可以应对振子耦合拓扑图不连通情况的结论. 最后, 通过两组具有不同噪声强度的仿真实验验证了理 论分析结果.     

Synchronization of Complex Networks with Coupled and Self‐Feedback Delays Via Aperiodically Intermittent Strategy

In this paper, we concern the exponential synchronization problem for hybrid‐coupled delayed dynamical networks via aperiodically intermittent control. Different from previous works, the delayed coupling term considered here contains the transmission delay and self‐feedback delay, and the intermittent control can be aperiodic. By utilizing a different technique compared with some previous results, several useful criteria are derived analytically to realise exponential synchronization for a class of coupled complex network. As a special case, some sufficient conditions ensuring the exponential synchronization for a class of coupled neural network are obtained. Finally, a numerical example is given to demonstrate the validness of the proposed scheme.     

Pinning dynamic systems of networks with Markovian switching couplings and controller–node set

In this paper, we study pinning control problem of coupled dynamical systems with stochastically switching couplings and stochastically selected controller–node set. Here, the coupling matrices and the controller–node sets change with time, induced by a continuous-time Markov chain. By constructing Lyapunov functions, we establish tractable sufficient conditions for exponential stability of the coupled system. Two scenarios are considered here. First, we prove that if each subsystem in the switching system, i.e. with the fixed coupling, can be stabilized by the fixed pinning controller–node set, and in addition, the Markovian switching is sufficiently slow, then the time-varying dynamical system is stabilized. Second, we conclude that if the system with the average coupling and pinning gains can be stabilized and the switching is sufficiently fast, the time-varying system is stabilized. Two numerical examples are provided to demonstrate the validity of these theoretical results, including a switching dynamical system between several stable subsystems, and a dynamical system with mobile nodes and spatial pinning control towards the nodes when these nodes are being in a pre-designed region.