Pinning control of weighted general complex dynamical networks with time delay

Time delays commonly exist in the real world. In the present work we consider weighted general complex dynamical networks with time delay, which are undirected and connected. Control of such networks, by applying local feedback injections to a fraction of network nodes, is investigated for both continuous-time and discrete-time cases. Both delay-independent and delay-dependent asymptotical stability criteria for network stabilization are derived. It is also shown that the whole network can be stabilized by controlling only one node. The efficiency of the derived results was illustrated by numerical examples.     

Fault diagnosis of time-delay complex dynamical networks using output signals

This paper proposes a novel approach for fault diagnosis of a time-delay complex dynamical network.Unlike the other methods,assuming that the dynamics of the network can be described by a linear stochastic model,or using the state variables of nodes in the network to design an adaptive observer,it only uses the output variable of the nodes to design an observer and an adaptive law of topology matrix in the observer of a complex network,leading to simple design of the observer and easy realisation of topology monitoring for the complex networks in real engineering.The proposed scheme can monitor any changes of the topology structure of a time-delay complex network.The effectiveness of this method is successfully demonstrated by virtue of a complex networks with Lorenz model.     

Topology identification for a class of complex dynamical networks using output variables

A problem of topology identification for complex dynamical networks is investigated in this paper. An adaptive observer is proposed to identify the topology of a complex dynamical networks based on the Lyapunov stability theory. Here the output of the network and the states of the observer are used to construct the updating law of the topology such that the communication resources from the network to its observer are saved. Some convergent criteria of the adaptive observer are derived in the form of linear inequality matrices. Several numerical examples are shown to demonstrate the effectiveness of the proposed observer.     

Adaptive function projective synchronization of uncertain complex dynamical networks with disturbance

We investigate the problem of function projective synchronization (FPS) in drive-response dynamical networks with non-identical nodes. An adaptive controller is proposed for the FPS of complex dynamical networks with uncertain parameters and disturbance. Not only are the unknown parameters of the networks estimated by the adaptive laws obtained from the Lyapunov stability theory and Taylor expansions, but the unknown bounded disturbances are also simultaneously conquered by the proposed control. Finally, a numerical simulation is provided to illustrate the feasibility and effectiveness of the obtained result.     

Generating weighted community networks based on local events

Many realistic networks have community structures, namely, a network consists of groups of nodes within which links are dense but among which links are sparse. This paper proposes a growing network model based on local processes, the addition of new nodes intra-community and new links intra- or inter-community. Also, it utilizes the preferential attachment for building connections determined by nodes' strengths, which evolves dynamically during the growth of the system. The resulting network reflects the intrinsic community structure with generalized power-law distributions of nodes' degrees and strengths.     

Synchronization of coupled dynamical chaotic networks via scalar controllers

Some scalar linear controllers, which can ensure that the states of coupled chaotic dynamical networks asymptotically synchronize each other, are derived on the basis of high gain state feedback control. Numerical simulation is given to validate the proposed theoretical result.     

Impulsive synchronization of two coupled complex networks with time-delayed dynamical nodes

In this paper, we investigate the impulsive synchronization between two coupled complex networks with time-delayed dynamical nodes. Based on the Lyapunov stability, the linear feedback control and the impulsive control theories, the linear feedback and the impulsive controllers are designed separately. By using the generalized Barbalat's lemma, the global asymptotic impulsive synchronization of the drive—response complex networks is derived and some corresponding sufficient conditions are also obtained. Numerical examples are presented to verify the effectiveness and the correctness of the synchronization criteria.     

Cluster synchronization in fractional-order complex dynamical networks

Cluster synchronization of complex dynamical networks with fractional-order dynamical nodes is discussed in the Letter. By using the stability theory of fractional-order differential system and linear pinning control, a sufficient condition for the stability of the synchronization behavior in complex networks with fractional order dynamics is derived. Only the nodes in one community which have direct connections to the nodes in other communities are needed to be controlled, resulting in reduced control cost. A numerical example is presented to demonstrate the validity and feasibility of the obtained result. Numerical simulations illustrate that cluster synchronization performance for fractional-order complex dynamical networks is influenced by inner-coupling matrix, control gain, coupling strength and topological structures of the networks.     

一类输出耦合时延复杂动态网络故障诊断研究

文章针对一类输出耦合时延复杂动态网络模型,考虑节点动力学参数未知的情况,基于网络外部同步思想,提出一种对该类复杂动态网络进行故障诊断的方法.利用节点的输出变量作为反馈变量设计控制器,根据Lyapunov稳定性理论,推导网络达到外部同步的条件.该方法可以实时监控时延网络拓扑结构的变化情况,对网络进行故障诊断.通过仿真验证本文方法的有效性. 关键词： 复杂动态网络 时延 故障诊断 节点参数     

基于混沌神经网络的单向Hash函数

提出了一种基于混沌神经网络的单向Hash函数，该方法通过使用以混沌分段线性函数作为输出函数的神经网络和基于时空混沌的密钥生成函数实现明文和密钥信息的混淆和扩散，并基于密码块连接模式实现对任意长度的明文序列产生128位的Hash值.理论分析和实验结果表明，提出的Hash函数可满足所要求的单向性，初值和密钥敏感性，抗碰撞性和实时性等要求. 关键词： 混沌神经网络 Hash函数 分段线性混沌映射 时空混沌     

Stochastic synchronization for time-varying complex dynamical networks

This paper studies the stochastic synchronization problem for time-varying complex dynamical networks. This model is totally different from some existing network models. Based on the Lyapunov stability theory, inequality techniques, and the properties of the Weiner process, some controllers and adaptive laws are designed to ensure achieving stochastic synchronization of a complex dynamical network model. A sufficient synchronization condition is given to ensure that the proposed network model is mean-square stable. Theoretical analysis and numerical simulation fully verify the main results.     

Adaptive pinning synchronization in fractional-order complex dynamical networks

Synchronization of general complex dynamical networks with fractional-order dynamical nodes is addressed in this paper. Based on the stability theory of fractional-order differential systems and adaptive pinning control, some sufficient local asymptotical synchronization criteria and global asymptotical ones are derived respectively, which succeed in solving the problem about how many nodes are need to be controlled and how much coupling strength should be applied to ensure the synchronization of the entire fractional-order networks. The obtained results are more general and effective than those reported. Moreover, the coupling-configuration matrices and the inner-coupling matrices are not assumed to be symmetric and irreducible. Finally, a numerical simulation is presented to demonstrate the validity and feasibility of the proposed synchronization criteria.     

Robust adaptive synchronization of uncertain and delayed dynamical complex networks with faulty network

<正>This paper presents a new robust adaptive synchronization method for a class of uncertain dynamical complex networks with network failures and coupling time-varying delays.Adaptive schemes are proposed to adjust controller parameters for the faulty network compensations,as well as to estimate the upper and lower bounds of delayed state errors and perturbations to compensate the effects of delay and perturbation on-line without assuming symmetry or irreducibility of networks.It is shown that,through Lyapunov stability theory,distributed adaptive controllers constructed by the adaptive schemes are successful in ensuring the achievement of asymptotic synchronization of networks in the present of faulty and delayed networks,and perturbation inputs.A Chua's circuit network example is finally given to show the effectiveness of the proposed synchronization criteria.     

基于二维超混沌映射的单向Hash函数构造

快速有效的单向Hash函数的设计是现代密码学研究的一个热点.提出了一种基于二维超混沌映射的单向Hash函数的构造方法.该方法将原始输入报文按字节进行线性变换以及混沌映射，在所产生的混沌序列中选值作为二维超混沌映射的初始值，对迭代后所得的超混沌信号经过调制构造单向Hash函数.实验与分析结果表明，这种构造方法实现简单、对初值有高度敏感性、具有很好的单向性、弱碰撞性和保密性能. 关键词： 单向Hash函数 二维超混沌 混沌映射     

Dynamical robustness analysis of weighted complex networks

Robustness of weighted complex networks is analyzed from nonlinear dynamical point of view and with focus on different roles of high-degree and low-degree nodes. We find that the phenomenon for the low-degree nodes being the key nodes in the heterogeneous networks only appears in weakly weighted networks and for weak coupling. For all other parameters, the heterogeneous networks are always highly vulnerable to the failure of high-degree nodes; this point is the same as in the structural robustness analysis. We also find that with random inactivation, heterogeneous networks are always more robust than the corresponding homogeneous networks with the same average degree except for one special parameter. Thus our findings give an integrated picture for the dynamical robustness analysis on complex networks.     

Pinning control of complex dynamical networks with general topology

Recently, the researches on pinning control of complex dynamical networks have mainly focused on such networks with very specific coupling schemes (e.g., symmetric coupling, uniform coupling and linear coupling). However, most real networks often consist of local units, which interact with each other via asymmetric and heterogeneous connections. In this paper, pinning control of a continuous-time complex dynamical network with general coupling topologies is studied. Some generic stability criteria based on master stability function (MSF) are derived for such a general controlled network, which guarantee that the whole network can be pinned to its equilibrium by placing feedback control only on a small fraction of nodes. Then, these results are extended to discrete-time case. Previous results about symmetric, uniform or linear coupled networks in this area are included as special cases of the present work. Numerical simulations of directed networks with weighted coupling pinned by specifically selective pinning scheme are given for illustration and verification.     

基于广义混沌映射切换的单向Hash函数构造

如何设计快速高效的单向Hash函数一直是现代密码学研究中的一个热点.提出了一种基于广 义混沌映射切换的Hash函数构造方法.这种方法首先构建产生多种混沌序列的广义混沌映射 模型,然后在明文信息的不同位置根据切换策略产生不同的混沌序列,并用线性变换后的信号 信息对混沌参数进行调制来构造单向Hash函数.初步分析了利用混沌映射实现单向Hash函数 的不可逆性、防伪造性、初值敏感性等特点.研究结果表明:这种基于广义混沌映射切换的Ha sh函数具有很好的单向性、弱碰撞性，较基于单一混沌映射的Hash函数具有更强的保密性能 ，且实现简单. 关键词： Hash函数 混沌 混沌映射切换