Pinning Synchronization in Networked Lagrangian Systems

This paper investigates the synchronization problem of networked Lagrangian systems based on pinning control framework on complex networks. We propose a pinning algorithm to guarantee the controlled synchronization of networked identical Lagrangian systems by applying local linear feedback injections to a small fraction of nodes. We also present some simple yet generic criteria on pinning synchronization for such an algorithm over undirected connected graphs, where all the agents are regulated to follow a synchronization state. Furthermore, the pinning controllability in networked Lagrangian systems is also discussed. Compared with some existing works on networked Lagrangian systems, the distinctive advantages of the proposed pinning algorithm include: (i) independence on the knowledge of system models; (ii) explicit consideration of agent's intrinsic complex dynamics; and (iii) simplicity of implement procedure in practice. Subsequently, the results are illustrated by a typical Lagrangian network composing of eight two‐link revolute manipulators. Numerical simulations with different kinds of pinning schemes are finally given to demonstrate the effectiveness of the proposed control methodology.     

Networked H∞ control of linear systems with state quantization

This paper addresses the problem of H_∞ controller design for linear systems over digital communication networks. A new model is proposed to describe both the network conditions and the state quantization of the networked control systems in a unified framework. From this model, a quantized state feedback strategy is developed for global and asymptotical stabilization of the networked control systems. The same H_∞ disturbance attenuation level as that in the case without quantization is achieved. Numerical examples are given to demonstrate the effectiveness of the proposed method.     

Programs as partial graphs II: Recursion

In Part I of the paper, we have proposed a unified relational algebra approach using partial graphs for theoretical investigations on semantics, correctness and termination. This approach is extended here to systems of recursive programs, allowing not only sequencing and conditional branching as a control structure but also flow diagrams.An equivalence proof of operational and denotational semantics is obtained which is strictly based on axioms of relational algebra. A short new proof of an important completeness result is given in the generalized setting of systems of recursive flow diagram programs. Finally, Hitchcock-Park's theorem on derivatives is formulated in the general case of nondeterministic recursive flow diagram programs.     

Finite-time consensus for controlled dynamical systems in network

The key challenges in networked dynamical systems are the component heterogeneities, nonlinearities, and the high dimension of the formulated vector of state variables. In this paper, the emphasise is put on two classes of systems in network include most controlled driftless systems as well as systems with drift. For each model structure that defines homogeneous and heterogeneous multi-system behaviour, we derive protocols leading to finite-time consensus. For each model evolving in networks forming a homogeneous or heterogeneous multi-system, protocols integrating sufficient conditions are derived leading to finite-time consensus. Likewise, for the networking topology, we make use of fixed directed and undirected graphs. To prove our approaches, finite-time stability theory and Lyapunov methods are considered. As illustrative examples, the homogeneous multi-unicycle kinematics and the homogeneous/heterogeneous multi-second order dynamics in networks are studied.     

复杂网络中的邻域重叠社团结构探测

网络,数学家们称其为图,它为许多复杂系统的结构提供了一个很好的抽象,从社会网络、计算机网络,到生物网络以及物理系统的状态空间。在过去的几十年里出现了许多确定网络系统拓扑结构的改进实验,但对实验产生的数据进行科学的分析,仍然存在本质的挑战。目前的社团检测中主要存在两个问题:一是不知道网络中有几个社团;二是网络中的顶点可能属于不同的社团,也就是社团中存在重叠结构。为了了解各种重叠社团检测算法的思想、实现步骤、优缺点比较、算法应用,文中对邻域重叠社团检测算法进行了深入的分析,以k-means算法分析了经济网络,同时采用Silhouette指标解决了最佳聚类数的问题,并通过仿真实验证明了此算法的可能性。     

MatrixExplorer: a dual-representation system to explore social networks

MatrixExplorer is a network visualization system that uses two representations: node-link diagrams and matrices. Its design comes from a list of requirements formalized after several interviews and a participatory design session conducted with social science researchers. Although matrices are commonly used in social networks analysis, very few systems support the matrix-based representations to visualize and analyze networks. MatrixExplorer provides several novel features to support the exploration of social networks with a matrix-based representation, in addition to the standard interactive filtering and clustering functions. It provides tools to reorder (layout) matrices, to annotate and compare findings across different layouts and find consensus among several clusterings. MatrixExplorer also supports node-link diagram views which are familiar to most users and remain a convenient way to publish or communicate exploration results. Matrix and node-link representations are kept synchronized at all stages of the exploration process     

网络结构化多Agent系统的任务分配

网络结构化多Agent系统既包括系统运行的底层物理网络,还包括Agent之间的交互网络。传统的任务分配方式并没有深入考虑到网络结构化的特点。文中首先论述网络结构化多Agent系统中任务分配的特点,介绍和分析基于底层网络拓扑与资源分布的任务分配方式、基于Agent交互网络与资源分布的任务分配方式和基于综合网络情境资源的任务分配方式。然后对相关工作进行综述,并与网络结构化多Agent系统任务分配模型进行比较分析。最后论述该方向的难点和未来要解决的问题。     

Modeling and simulation of large-scale,linear, multiport systems

A large number of physical and engineering systems may be represented directly in terms of component energy characteristics and their power interactions. When the system elements are modeled as energetic multiports, and their interconnections by power bonds, then the bond graph language is a natural one for describing the entire system. Bond graphs may be written for dynamic systems involving various energy types, such as electrical, mechanical, fluid and thermal; all energy types may be coexistent. Useful modeling elements include multiport storages, dissipators, and junction elements and transducers, as well as sources.Bond graph models of linear multiport systems may be transformed to state-space form by a powerful algorithm based upon operational causality. From the state-space equations, dynamic responses may be obtained by the matrix exponential technique, thereby allowing the direct digital simulation of linear multiport models.The ENPORT program is a realization of the bond graph reduction algorithm. It is a principal purpose of this paper to describe the procedure upon which ENPORT is based, and to present some results. Important features of ENPORT are its choice of physically significant state variables, its use of operational causality to obtain an orderly formulation of system equations, and its ability to handle systems containing static storage subfields.     

Estimation,filtering and fusion for networked systems with network-induced phenomena: New progress and prospects

In this paper, some recent advances on the estimation, filtering and fusion for networked systems are reviewed. Firstly, the network-induced phenomena under consideration are briefly recalled including missing/fading measurements, signal quantization, sensor saturations, communication delays, and randomly occurring incomplete information. Secondly, the developments of the estimation, filtering and fusion for networked systems from four aspects (linear networked systems, nonlinear networked systems, complex networks and sensor networks) are reviewed comprehensively. Subsequently, some recent results on the estimation, filtering and fusion for systems with the network-induced phenomena are reviewed in great detail. In particular, some latest results on the multi-objective filtering problems for time-varying nonlinear networked systems are summarized. Finally, conclusions are given and several possible research directions concerning the estimation, filtering, and fusion for networked systems are highlighted.     

分布式网络控制系统的研究

综述了网络控制系统的出现背景、概念和特性,阐明了网络的应用给传统控制系统带来的益处及广阔的应用前景,分析了网络传输数据给网络控制系统带来的问题,并阐述了网络控制系统中不同于一般网络系统的通信问题,详细分析了近年来迅速发展的现场总线和以太网在分布式网络控制系统中的发展趋势。最后概述了网络控制系统当前的研究现状。指出将网络通信调度和系统控制结合起来,将基于假设的理论研究同基于实际对象的实验平台相结合,是未来的发展趋势。     

空间多体机械系统耦合动力学的键合图法

为提高多能域耦合空间多体系统动力学分析的效率及可靠性,提出了键合图法．从能量守恒的基本原理出发,讨论了键合图中的多通口元件MTF所具有的特性．以此为基础阐述了建立空间多体机械系统键合图模型的一般方法及其动力学原理．将运动副约束反力视做未知势源加在系统键合图模型相应的0-结处,有效地解决了微分因果关系及非线性结型结构所带来的十分困难的代数问题,推导出便于计算机自动生成的系统状态方程及运动副约束反力方程的统一公式,实现了计算机自动建模与仿真．实际算例表明了所述方法的有效性．     

Controllability of multi-agent systems based on agreement protocols

This paper investigates the controllability of multi-agent systems based on agreement protocols. First, for a group of single-integrator agents, the controllability is studied in a unified framework for both networks with leader-following structure and networks with undirected graph. Some new necessary/sufficient conditions for the controllability of networks of single-integrator agents are established. Second, we prove that, under the same topology and same prescribed leaders, a network of high-order dynamic agents is completely controllable if and only if so is a network of single-integrator agents. Third, how the selection of leaders and the coupling weights of graphs affect the controllability is analyzed. Finally, some numerical simulations are presented to demonstrate the effectiveness of the theoretical results.     

Networked Control Systems: A Survey of Trends and Techniques

Networked control systems are spatially distributed systems in which the communication between sensors, actuators,and controllers occurs through a shared band-limited digital communication network. Several advantages of the network architectures include reduced system wiring, plug and play devices,increased system agility, and ease of system diagnosis and maintenance. Consequently, networked control is the current trend for industrial automation and has ever-increasing applications in a wide range of areas, such as smart grids, manufacturing systems,process control, automobiles, automated highway systems, and unmanned aerial vehicles. The modelling, analysis, and control of networked control systems have received considerable attention in the last two decades. The ‘control over networks’ is one of the key research directions for networked control systems. This paper aims at presenting a survey of trends and techniques in networked control systems from the perspective of ‘control over networks’, providing a snapshot of five control issues: sampled-data control, quantization control, networked control, event-triggered control, and security control. Some challenging issues are suggested to direct the future research.     

复杂网络与网络化软件系统

复杂网络理论是对复杂系统的高度抽象,实证研究发现网络化复杂软件系统的拓扑结构具有复杂网络的特征.复杂网络理论的最新研究成果,为网络化复杂软件系统的开发提供了新的数学基础.提出一种基于复杂网络的网络化软件工程,探讨了复杂网络理论在网络化复杂软件系统的建模、测试和度量中的应用.     

δ算子下的网络控制系统最优控制方法

研究网络控制系统的随机最优控制问题,提出了针对随机时延的网络控制系统最优控制律和二次型性能指标极小的控制律设计方案．在δ算子域内应用动态规划理论．设计网络控制系统的最优状态反馈和输出反馈控制律,得到的线性二次型高斯控制器可对系统中的随机长时延进行动态补偿．最后通过实例仿真验证了上述最优控制方案的可行性和有效性．     

Declarative secure distributed information systems

We present a unified declarative platform for specifying, implementing, and analyzing secure networked information systems. Our work builds upon techniques from logic-based trust management systems and declarative networking. We make the following contributions. First, we propose the Secure Network Datalog (SeNDlog) language that unifies Binder, a logic-based language for access control in distributed systems, and Network Datalog, a distributed recursive query language for declarative networks. SeNDlog enables network routing, information systems, and their security policies to be specified and implemented within a common declarative framework. Second, we extend existing distributed recursive query processing techniques to execute SeNDlogprograms that incorporate secure communication via authentication and encryption among untrusted nodes. Third, we demonstrate the use of user-defined cryptographic functions for customizing the authentication and encryption mechanisms used for securing protocols. Finally, using a local cluster and the PlanetLab testbed, we perform a detailed performance study of a variety of secure networked systems implemented using our platform.     

高阶时滞多智能体系统一致性控制

本文讨论了多输入网络化时滞多智能体系统的一致性问题.应用无向或有向图描述网络化系统的拓扑结构.多智能体的一致性收敛问题可以转化为线性时滞系统的稳定性问题.通过双线性矩阵不等式可以得到高阶多智能体系统时滞相依以及时滞独立的一致性准则.最后,举例一个无向拓扑结构的时滞多智能体来说明本文方法的有效性.     

Independency relationships and learning algorithms for singly connected networks

Graphical structures such as Bayesian networks or Markov networks are very useful tools for representing irrelevance or independency relationships, and they may be used to efficiently perform reasoning tasks. Singly connected networks are important specific cases where there is no more than one undirected path connecting each pair of variables. The aim of this paper is to investigate the kind of properties that a dependency model must verify in order to be equivalent to a singly connected graph structure, as a way of driving automated discovery and construction of singly connected networks in data. The main results are the characterizations of those dependency models which are isomorphic to singly connected graphs (either via the d-separation criterion for directed acyclic graphs or via the separation criterion for undirected graphs), as well as the development of efficient algorithms for learning singly connected graph representations of dependency models.     

Polynomial-based graph convolutional neural networks for graph classification

Machine Learning - Graph convolutional neural networks exploit convolution operators, based on some neighborhood aggregating scheme, to compute representations of graphs. The most common...