Random adaptive control for cluster synchronization of complex networks with distinct communities

In this paper, we investigate the cluster synchronization for complex networks with time‐varying delayed couplings, stochastic disturbance, and non‐identical nodes in different clusters. Based on randomly occurring controllers, some Bernoulli stochastic variables are introduced to describe the controllers, then, a fraction of nodes in clusters, which have direct connections to the other clusters, is controlled, and the states of the whole dynamical networks can be globally forced to the objective cluster states. Sufficient conditions are derived to guarantee the realization of the mean square cluster synchronization pattern for all initial values by means of Lyapunov stability theory, It differential formula, and LMI approach. Besides, by designing the randomly occurring adaptive update law, some suitable control gains are obtained. Finally, numerical simulations are also given to demonstrate the effectiveness and validity of the main result. Copyright © 2015 John Wiley & Sons, Ltd.     

Pinning synchronization of nonlinear hybrid-coupled complex networks with double time delays via aperiodically intermittent adaptive control

In this article, the synchronization problem for nonlinear hybrid-coupled complex networks with both coupling and internal self-feedback delays is studied. An aperiodically intermittent adaptive control is employed for a fraction of nodes to pin the whole network to the synchronization state. Some sufficient conditions for realizing global synchronization are derived based on Halanay inequality and Lyapunov stability theory. Finally, a simulation example verifies the effectiveness of the proposed control method.     

Synchronization in nonlinear complex networks with multiple time‐varying delays via adaptive aperiodically intermittent control

This article is concerned with the problem of synchronization in nonlinear complex networks with multiple time‐varying delays via adaptive aperiodically intermittent control. The couplings inside nodes are assumed to be nonlinear and subject to multiple time‐varying delays. Meanwhile, the connection topology among the nodes can be directed and weighted. Then, the adaptive aperiodically intermittent control method is employed to realize synchronization and automatic modification to compensate the changes in dynamic errors. In addition, several synchronization criteria are rigorously induced based on the Lyapunov stability theory. Finally, the proposed control method is evaluated by utilizing numerical simulation. The results can be also applied to linear complex networks with delays.     

Adaptive synchronization of fractional‐order complex networks via pinning control

Adaptive synchronization of a class of fractional‐order complex networks is investigated in this paper. On the basis of the fractional‐order system stability theory, adaptive synchronization criteria of fractional‐order complex networks with 0 < q < 1 is achieved. Furthermore, pinning control method is then suggested to control the networks, and adaptive strategy is employed to tune the control gains and coupling strength. Because the nodes with high degree may not be the center of the networks, a new attempt to choose the pinned nodes on the basis of the closeness centrality scheme is proposed. Finally, numerical simulations are given to verify the effectiveness of the proposed approach based on the closeness centrality scheme. Copyright © 2012 John Wiley & Sons, Ltd.     

基于生存周期的自组网同步研究

主从式同步作为TDMA方式下自组网同步方式的一种,因其同步精度高、收敛速度快而被广泛研究.为了提高同步的收敛速度和同步精度,解决已有的主从式同步方法中存在的一些问题,文章利用网络节点的生存周期提出一种新的自组网同步方法.首先结合具体时帧设计和时隙接人详细论述了同步方法的实现过程,随后通过OPNET仿真软件对不同接入情况下所有网络节点的收敛时间和同步精度进行了测试.仿真结果表明即使当节点接入冲突数量达到最大时,在不同的入网状态下,所有节点中最长的同步收敛时间也不超过1 S,并且源节点和距离6跳的节点之间的同步误差只有0.37 ms,验证了同步方法的快速收敛性和精确性.     

Pinning synchronization of fractional‐order complex networks with adaptive coupling weights

This work studies the issue of synchronization control for a type of fractional‐order complex networks, in which the adaptive coupling matrix is considered under the directed topology structure. A pinning control strategy, with the free selection of pinning nodes, is adopted for the synchronization goal. Then, by absorbing the information of eigenvectors and adaptive laws for the coupling matrix, a new Lyapunov function is constructed, by which, and with the assistance of Gronwall inequality and network features, the sufficient condition for Mittag‐Leffler synchronization of the fractional‐order network is established. Accordingly, an easy verifiable algebraic criterion is further derived by means of some matrix inequalities. Besides, we also discuss the effect of outer coupling strength on the achievement of network synchronization. Finally, a numerical experiment is performed to show the evidence of the correctness and effectiveness of the proposed results.     

Fault tolerant synchronization for a class of complex interconnected neural networks with delay

This paper is concerned with the fault tolerant synchronization problem for a class of complex interconnected neural networks against sensor faults. As sensor faults may lead to performance degradation or even instability of the whole network, fault tolerant control laws are designed to guarantee the controlled synchronization of the complex interconnected neural networks. On the basis of Lyapunov stability theory and adaptive schemes, three kinds of fault tolerant control laws are designed on the basis of linear matrix inequality technique. One is the passive fault tolerant control law, the other two are adaptive fault tolerant control laws. The latter two methods use the adaptive adjusting mechanism of the coupling coefficients to ensure the synchronization of the networks in the presence of sensor faults. Simulation results are given to verify the effectiveness of the proposed methods. Copyright © 2013 John Wiley & Sons, Ltd.     

Stability and synchronization of directed complex dynamical networks with random packet loss: the continuous‐time case and the discrete‐time case

This paper presents models for both the continuous‐time and discrete‐time directed complex dynamical networks (CDNs) with random packet loss, respectively. The packet loss may take place in the communication between every two neighbor nodes. The exponential mean‐square stability and the exponential mean‐square synchronization for both the continuous‐time and discrete‐time CDNs with random packet loss are investigated, respectively, by defining the packet loss probability matrix. In addition, two special cases, the CDN with synchronous packet loss and the CDN with node‐dependent packet loss, are discussed. Numerical examples are provided for illustrations. Copyright © 2012 John Wiley & Sons, Ltd.     

Fixed-time synchronization for discontinuous delayed complex-valued networks with semi-Markovian switching and hybrid couplings via adaptive control

In this article, the global fixed-time synchronization issue is considered for semi-Markovian switching discontinuous complex-valued dynamical networks (CVDNs) with hybrid couplings and time-varying delays, in which CVDNs are not divided into two real value systems, contrary to existing literature. First, a new fixed-time convergence principle for complex-valued nonlinear system with semi-Markovian switching is developed. Second, to realize the fixed-time synchronization, the state feedback controller with integral term and adaptive controller are designed, respectively. Under the complex-valued differential inclusions framework, by utilizing Lyapunov-Krasovskii functional method and inequality analysis technique, the global fixed-time synchronization conditions are addressed in terms of linear matrix inequalities. Finally, two numerical simulations are given to illustrate the validity of the presented theoretical results.     

基于多属性决策的电力通信网的节点重要度计算方法

随着电网规模不断扩大,作为电网的支撑网络,电力通信网络的结构变得更加复杂且脆弱。预先识别和保护电力通信网中的重要节点是降低网络脆弱性的有效方法。为了全面地分析电力通信网中的节点,从网络中节点的局部信息、全局信息以及节点承载的业务重要度量化节点的重要性,提出一种基于多属性决策的电力通信网节点重要性计算方法。该算法首先根据各节点指标计算指标熵值以及指标之间的肯德尔系数,确定指标权重,结合多属性决策方法得到节点指标贴近度,进而得到各节点的实际重要度。最后根据不同节点重要度计算方法,分别攻击小型电力通信网、传统复杂网络、市级电力通信网中的节点,分析对网络指标的影响,证实该方法的合理性。     

Technologies for Quantum Key Distribution Networks Integrated With Optical Communication Networks

Secure networks composed of optical networks and quantum key distribution (QKD) are considered in this paper. A network layer structure is defined to focus on issues important with respect to the QKD network layer that controls QKD links and supplies a secure key for message transmission. A multiple-user QKD network layer can be constructed with timing synchronization, secure key sharing between indirectly connected nodes with switched QKD systems and key relays, and key management to control the volume of key generation and supply in response to the demand from optical network nodes.      

Fixed time synchronization of delayed chaotic neural networks by using active adaptive control

This article aims to investigate the fixed time synchronization of a class of chaotic neural systems by way of adaptive control method. Using Lyapunov stability theory, a new fixed time stability theorem which plays an important role on the synchronization scheme is presented at first. Then, combining the fixed time stability theorem and adaptive control technique, an adaptive control scheme has been developed to achieve the fixed time synchronization of chaotic neural systems. The proposed controllers assure the global convergence of the error dynamics in fixed-time based on the Lyapunov stability theory. Furthermore, the proposed control strategy cannot only provide a fast convergence rate, but also afford a bounded convergence time which is unrelated to the initial values and easy to work out by using the simple time calculation formula. Finally, numerical simulations are presented by taking a typical two-order chaotic neural system as an example to verify and demonstrate the effectiveness of the proposed scheme.     

Robust control of delayed Cohen–Grossberg neural networks

In this paper, robust control of Cohen–Grossberg neural networks with time delays is considered based on Lyapunov functional method and matrix inequality technique. Several new controllers with time delays and without time delays are designed to ensure the global asymptotic stability of equilibrium point, respectively. Finally, simulation examples are constructed to justify the proposed theoretical analysis. Copyright © 2007 John Wiley & Sons, Ltd.     

Bounded synchronization of complex dynamical networks with prescribed performance via event‐based transmission strategy

This paper addresses a novel prescribed performance synchronization of complex dynamical networks by means of event‐triggered communication protocols. With the designed controller and proposed even‐triggered communication strategy, this paper have advantages of guaranteeing the transient and steady‐state performance of complex dynamic networks and avoiding the continuous communication of networks for reducing the number of communications and saving the network resources. In addition, the Zeno behavior is avoided in the networks. At last, the effectiveness of the theoretic results obtained is verified via the application in the complex dynamical network with Chua's circuit.     

Stability analysis and robust synchronization of fractional‐order competitive neural networks with different time scales and impulsive perturbations

This article mainly examine a class of robust synchronization, global stability criterion, and boundedness analysis for delayed fractional‐order competitive type‐neural networks with impulsive effects and different time scales. Firstly, by endowing the robust analysis skills and a new class of Lyapunov‐Krasovskii functional approach, the error dynamical system is furnished to be a robust adaptive synchronization in the voice of linear matrix inequality (LMI) technique. Secondly, by ignoring the uncertain parameter terms, the existence of equilibrium points are established by means of topological degree properties, and the solution representation of the considered network model are provided. Thirdly, a novel global asymptotic stability condition is proposed in the voice of LMIs, which is less conservative. Finally, our analytical results are justified with two numerical examples with simulations.     

基于层次结构的无线传感器网络时间同步研究

结合变电站运维管理的工业现场特点,和无线传感器网络时间同步协议的研究,提出了汇聚节点的双向时间同步定时偏差补偿与传感节点虚拟双向同步相结合的时间同步算法。在网络部署的初期,按照模型布置网关节点和汇聚节点,汇聚节点和传感节点采用不同的时间同步方法。仿真实验表明网络收敛时间和同步精度具有良好性能。     

低功耗单跳无线网络实时数据采集系统设计

单跳无线网络监控方便、传输路由简单,提出以单跳无线网络架构实时数据采集系统。由时间同步和轮询阶段组成的周期工作机制,在轮询阶段传感节点进行周期性激活与休眠。设计了由CC2500射频模块和C8051F330/320单片机组成的节点硬件平台,提出通过减少节点活动时长和降低系统时钟频率对传感节点进行低功耗设计。由节点硬件平台组建了一个多点温度同步采集系统,通过实际测试,温度采集数据能实时传送,传感节点的能量节约效果显著。     

Congestion control for TCP/AQM networks using state predictive control

The purpose of this paper is to design congestion controllers for TCP/AQM networks using state predictive control and to illustrate the effectiveness of the resulting congestion controllers via SIMULINK and the ns‐2 simulator. Linearized models of TCP/AQM networks can be simply described as linear systems with information delay. Using state predictive control, these linear systems with an information delay are equivalent to linear systems with no delay. Thus, congestion controllers (AQM mechanisms) can be designed by using linear control theory. In this paper, LQ control with an observer is adopted for linear systems with no delay which describe linearized systems of TCP/AQM networks. Finally the designed state predictive controllers using LQ control with an observer are implemented and some simulation results obtained with SIMULINK and the ns‐2 simulator are presented. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(3): 41–47, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20405     

Individual Phase Control of a Static Compensator for Load Compensation and Voltage Balancing and Regulation

The purpose of this paper is to discuss the developments in control strategies for static compensators using programmable high speed digital controllers. Individual phase control of static compensators has been used in the past for balancing and power factor correction of arc furnace and single phase railway loads. With the advancements in programmable high speed controllers based on microprocessor technology, more complex computations can be accurately performed for the additional purpose of regulating and balancing the voltage feeding such loads. Other developments that will be discussed are the use of symmetrical firing angle control to eliminate the even harmonics in the current spectrum and hence, reduce the cost of filtering, and the synchronization of the controller to the phase-locked-loop firing circuit to compensate for frequency variations. The results of simulator studies will be presented.     

维持局部孤网稳定切换的网源荷分布式协调控制方法

由于土地、发电资源等条件的限制,现代大型城市主要由外部电网进行负荷供电,形成大型受端城市电网。大型受端城市电网与主系统解列后,功率不平衡会导致频率下降,甚至可能引发网络崩溃,维持其稳定切换以形成局部孤网供电具有重要的理论和现实意义。网源荷协调控制是维持局部孤网稳定切换的关键,然而,对于局部孤网,尤其是非计划形成的局部孤网,是较难实现集中式协调调控的。鉴于此,引入分布式多代理系统,提出一种无需集中控制器的网源荷分布式协调控制方法。有别于依赖集中控制器、且通信结构复杂的传统集中式控制方法,分布式协调控制在仅依靠相邻节点通信的状况下,通过改进的平均一致性算法获取电网运行全局参数,实现网源荷全局协调控制。该控制方法能够较好地适应网络结构变化,挖掘网源荷协调潜能。同时,提出的改进平均一致性算法具有更好的收敛性能,为局部孤网切换时的频率和电压控制提供快速全局数据支撑。基于PSCAD/EMTDC和Matlab仿真平台,在典型工况下对网源荷协调控制策略进行分析和验证,结果表明所提出的改进平均一致性算法和分布式网源荷协调控制方法能够维持局部孤网稳定切换。