Graph-theoretic characterisations of structural controllability for multi-agent system with switching topology

This article considers the controllability problem for multi-agent systems. In particular, the structural controllability of multi-agent systems under switching topologies is investigated. The structural controllability of multi-agent systems is a generalisation of the traditional controllability concept for dynamical systems, and purely based on the communication topologies among agents. The main contributions of this article are graph-theoretic characterisations of the structural controllability for multi-agent systems. It turns out that the multi-agent system with switching topology is structurally controllable if and only if the union graph 𝒢 of the underlying communication topologies is connected (single leader) or leader–follower connected (multi-leader). Finally, this article concludes with several illustrative examples and discussions of the results and future work.     

Further developments in output structural controllability and an assessment of structural techniques

Modifications have been made to the technique of output structural controllability to overcome some limitations of this useful technique. A critical assessment of the usefulness of various structural controllability techniques for control system synthesis is given through the analysis of key examples.     

Connectability and structural controllability of composite systems

The notion of connectability for multivariable composite systems consisting of a number of subsystems interconnected in an arbitrary way is introduced in this paper. It is shown that connectability plays a fundamental role in composite systems; in particular, it is shown that under certain mild conditions, almost all composite interconnected systems are controllable and observable from any nontrivial input and output if and only if the resultant composite system is connectable. A class of composite systems called general input-output hierarchical systems, which has the property of always being connectable is then defined. Since such systems are almost always controllable, this observation perhaps gives some insight in explaining why so many real world systems have as their basis a hierarchical structure. An application of the previous results is then made to show that a system (C, A, B) is structurally controllable and observable if and only if it is connectable and a certain non-pathological rank condition holds.     

Output strutural controllability: a tool for integrated process design and control

This paper seeks to expose the relative merits of output structural controllability (OSC) as an integrative tool for process design and control. Output structural controllability assists the design engineer in flow-sheet selection, via the elimination of uncontrollable flowsheets, and in control structure synthesis. The qualitative nature of the technique means that it can be performed at the early stages of design, when alternative flowsheets have been proposed, but quantitative design parameters are unknown. As such, OSC may significantly reduce the amount of quantitative modelling required, thereby providing a significant cost saving. Two industrial case studies are examined: a wet grinding circuit and the purification section of an ethylene oxide production plant. In both cases, a control structure is synthesised using a protoype software package developed at The University of Queensland. The control structure designs are seen to be operable recommendations, and similar to those employed by both operating companies; designs which were probably the result of much trial-and-error, many iterations and based on far greater (quantitative) information. The integration of process design and control is a difficult problem. This paper demonstrates that OSC is one tool which may be employed by process design and control engineers to address this problem.     

Reachability and controllability of a particle in a dielectrophoretic system

A dielectrophoretic (DEP) force is a result of the interaction between a nonuniform electric field and a polarizable particle. As the electric field is dominant at the micro/nano scale, this force can be effectively used to manipulate and control particles on this scale. We consider the motion of a particle on an invariant line with the suspending medium being a fluid with a low Reynolds number. This DEP system has two states and two parameters: the two states are indicative of the particle’s position and the induced dipole moment and the two parameters are α and c which depend upon the electric properties of the particle and the medium. The system is described by a set of ordinary differential equations with a quadratic term in the control variable (control being the applied voltage on the electrodes which induces the electric field) making the system non-affine in control. In the existing literature, the controllability studies of the DEP system have been restricted to reachability issues in the context of the time-optimal control problem. Here we present a comprehensive study of reachability, accessibility and controllability.     

二阶邻居协议下多智能体系统能控能观性保持

为了研究多智能体系统的一致性特点及能控、能观性保持策略,分析了具有时变拓扑结构的多智能体系统在一阶邻居协议和二阶邻居协议下的一致性速度,针对拓扑结构的特殊性,利用结构能控性性质和拉普拉斯矩阵第二小特征值与一致性速度之间存在的关系设计出一种使能控性和能观测性保持的控制策略。此外,得出多智能体系统在二阶邻居协议下,具有更快的一致性速度的结论。文中2个主要定理分别通过算例和仿真进行验证,算例和仿真结果与定理结论一致。     

欧氏空间货郎担问题的一个多项式时间近似方案的改进与实现

货郎担问题的实例是给定n个结点和任意一对结点{i,j}之间的距离di,j,要求找出一条封闭的回路,该回路经过每个结点一次且仅一次,并且费用最小,这里的费用是指回路上相邻结点间的距离和.货郎担问题是NP难的组合优化问题,是计算机算法研究的热点之一.在过去几十年中,这一经典问题成为许多重要算法思想的测试平台,并促使一些研究领域的出现,如多面体理论和复杂性理论.欧氏空间上的货郎担问题,结点限制在欧氏空间,距离定义为欧氏距离.即使是这样,欧氏空间上的货郎担问题仍然是NP难的.1996年,Arora提出欧氏空间上货郎担问题的第1个多项式时间近似方案.对其中货郎担问题的算法进行了改进：提出一种新的构造方法,使应用于该算法的“补丁引理”结论由常数6改进到常数3,从而使算法的时间复杂度大幅减少;同时,编程实现了该算法,并对实验结果进行了分析.     

Links between asymptotic controllability and persistence of excitation for a class of time-varying systems

For a class of nonlinear time-varying parameterized systems we prove that persistence of excitation implies global asymptotic controllability to the equilibrium with respect to a set of parameters. The result is used to derive sufficient conditions for global asymptotic controllability for composite systems.     

Robustness studies for H∞ feedback control in a structural acoustic model with periodic excitation

Results from an extensive study on the robustness of an H^∞ compensator for a 2-D structural acoustic model are presented. The effects of frequency uncertainties in an exogenous signal are studied for both the case where the signal is contained in the controller formulation and the case where it is excluded. Delays are inserted in the input and/or output signals and their effect on the controller performance is recorded. A comparison between the standard LQG/Kalman filter and the H^∞/Min-Max compensator reveals no significant differences in the overall controller performance. Modifications in the controller structure are studied to see whether loss of information (the tracking variable) that must be calculated a priori would result in performance degradation. This study provides valuable insight into the computational and implementational issues that arise when dealing with the control of large and complex systems that are governed by partial differential equations.     

On a method for solving a local boundary problem for a nonlinear stationary system with perturbations in the class of piecewise constant controls

The wide class of nonlinear stationary systems of ordinary differential equations taking into account restrictions on control and external perturbation is considered. An algorithm for constructing a discrete control function that guarantees the transfer of the systems from the initial state to the origin and an arbitrary neighborhood of the origin is proposed. A constructive sufficient condition of the Kalman type, in which the specified translation is possible, is obtained. The problem of robot‐manipulator control is considered and its numerical simulation is carried out.     

P-DOT: a model of computation for big data

In response to the high demand of big data analytics, several programming models on large and distributed cluster systems have been proposed and implemented, such as MapReduce, Dryad and Pregel. However, compared with high performance computing areas, the basis and principles of computation and communication behaviour of big data analytics is not well studied. In this paper, we review the current big data computational model DOT and DOT Advanced, and propose a more general and practical model p-DOT (p-phases DOT). p-DOT is not a simple extension, but with profound significance: for general aspects, any big data analytics job execution expressed in DOT model or bulk synchronous parallel model can be represented by it; for practical aspects, it considers I/O behaviour to evaluate performance overhead. Moreover, we provide a cost function of p-DOT implying that the optimal number of machines is near-linear to the square root of input size for a fixed algorithm and workload, and certify that the processing paradigm of p-DOT is scalable and fault-tolerant. Finally, we demonstrate the effectiveness of the model through several experiments.     

二维激光图像挠度/位移测量系统的结构性误差及解决方案研究

为提高二维激光图像挠度/位移测量系统的测量精度,通过对系统的结构特点及其可能造成误差的原因分析,从结构和设计上对系统进行了包括对称激光器安装、弱衍射激光准直装置和激光靶标的水平安装等方面的改进.通过改进,系统有效地消除了因结构原因造成的不稳定性,显著提高了系统精度.实验证明,改进后的系统精度大大提高并可投入工程中直接使用.     

民机结构修理支持系统中数据库的设计与实现

研究了用于民机结构修理支持系统的数据库系统的设计.为保证民机结构损伤修理的及时性和有效性,研究采用数据库管理技术来管理结构损伤评估和修理决策过程中的数据.在数据库的实现过程中,根据民机结构修理支持系统的流程,设计了数据库系统的体系结构和数据库的逻辑结构,并通过完整性约束及权限管理保证了数据库的安全和数据的正确.此外,利用ADO.NET数据库访问技术,实现了对数据库的连接与操作,并对系统中各数据库的应用进行了分析.     

Generic methodology for the probabilistic reliability assessment of some structural properties: a graph theoretical approach

The graphical characterisation of many important structural properties, such as controllability, observability, diagnosability of many kinds of structured systems, uses mainly four types of elementary graphical conditions: connectivity, complete matching, linking and distance conditions. Since structural properties depend on different associations of elementary conditions, it is interesting to study elementary conditions. This paper is the first part of this global approach based on elementary graphical conditions and we choose to study the so-called connectivity and complete matching conditions. Starting from the graphical representation associated with a system, the paper provides Boolean expressions of the connectivity and complete matching conditions based on the edges validity, which can be linked to the physical components operating state. These expressions can then be used to define and compute the reliability of a structural property knowing the reliability of the system physical components. This knowledge can be important during both conception and exploitation stages. The proposed methods are quite intuitive and simple to implement and have basically polynomial complexity orders. This makes our approach well suited to analyse large-scale systems.     

Stability and persistent disturbance attenuation properties for a class of networked control systems: switched system approach

In this paper, both the asymptotic stability and l ^∞ persistent disturbance attenuation issues are investigated for a class of networked control systems (NCSs) under bounded uncertain access delay and packet dropout effects. The basic idea is to formulate such NCSs as discrete-time switched systems with arbitrary switching. Then the NCSs' stability and performance problems can be reduced to the corresponding problems of such switched systems. The asymptotic stability problem is considered first, and a necessary and sufficient condition is derived for the NCSs' asymptotic stability based on robust stability techniques. Secondly, the NCSs' l ^∞ persistent disturbance attenuation properties are studied and an algorithm is introduced to calculate the l ^∞ induced gain of the NCSs. The decidability issue of the algorithm is also discussed. A network controlled integrator system is used throughout the paper for illustration.     

Impact of noise on self-rated job satisfaction and health in open-plan offices: a structural equation modelling approach

This study uses a structural equation model to examine the effects of noise on self-rated job satisfaction and health in open-plan offices. A total of 334 employees from six open-plan offices in China and Korea completed a questionnaire survey. The questionnaire included questions assessing noise disturbances and speech privacy, as well as job satisfaction and health. The results indicated that noise disturbance affected self-rated health. Contrary to popular expectation, the relationship between noise disturbance and job satisfaction was not significant. Rather, job satisfaction and satisfaction with the environment were negatively correlated with lack of speech privacy. Speech privacy was found to be affected by noise sensitivity, and longer noise exposure led to decreased job satisfaction. There was also evidence that speech privacy was a stronger predictor of satisfaction with environment and job satisfaction for participants with high noise sensitivity. In addition, fit models for employees from China and Korea showed slight differences.

Practitioner Summary: This study is motivated by strong evidence that noise is the key source of complaints in open-plan offices. Survey results indicate that self-rated job satisfaction of workers in open-plan offices was negatively affected by lack of speech privacy and duration of disturbing noise.     

时滞与界带

基于分析结构力学提出的界带分析方法,将子结构间的分界面延拓为有一定宽度的分界带/分界域,从而可以用于分析计算结构的非局部效应.分析动力学中存在弹性时滞积分问题,在理论方面仍存在许多有待明确的问题.通过分析结构力学与分析动力学间的模拟关系,可将界带分析方法用到弹性时滞积分问题中去,基于辛体系建立相应的分析计算方法.数值算例验证该套理论算法的可行性,也为进一步开展深入研究打下了理论基础.     

A novel structural modeling and analysis of VLSI interconnect with an RLC tree network system using a BG/SEBD approach

A practical and effective novel graphical structural modeling and analysis approach is presented.This approach is used for solving the state interactions modeling problem caused by the model approximations in VLSI interconnect for RLC tree network systems.The bond graph (BG) energy model with a simulink energy-based block diagram (SEBD) algorithm is developed.The dynamic behaviors of an example of VLSI interconnect with a 20th-order RLC tree are presented.Methods of sequent structuring and the delineation o...