On reachable set synthesis of delay Markovian jump systems under partially delay-dependent asynchronous control

This paper pays close attention to the reachable set synthesis problem for discrete-time delayed Markovian jump systems (DDMJSs) under partially asynchronous control. Different from the traditional controller, a class of partially asynchronous controller is proposed, where delay-free and delay states are comprised and cannot take place at the same time. In addition, Bernoulli variable is used to describe the probability distribution of the above two kinds of states, and the design of feedback controller is considered. On this basis, the sufficient conditions which the state feedback controller is existent are solved effectively by using linear matrix inequalities (LMIs). Furthermore, the results of reachable set synthesis are extended to the DDMJs with uncertain transition probabilities. Finally, several numerical simulations are given to show the effectiveness of the presented methods.     

The estimation of probability distribution of SDE by only one sample trajectory

This paper focuses on the method of the simulation of a stochastic system and the main method of our paper is the Monte Carlo computation simulation method. Taking the stochastic Logistic equation as an example, we present the simulation of the sample trajectory by Euler scheme and the invariant probability distribution of stochastic differential equations with the Monte Carlo method. We also compare the simulation result with the analytical result for the autonomous stochastic Logistic model. Moreover, the stochastic Logistic equation with Markovian switching which is described by a Markov chain taking values in a finite state space is considered.     

基于推广的概率分布区间分解法的时滞系统稳定性分析

基于推广的概率分布区间分解法,研究一类具有随机时滞系统的概率分布相关稳定性问题.充分利用随机时滞的概率分布信息,获得一系列稳定性判据;通过严格的数学证明,表明通过增加概率区间数可以逐渐降低稳定性判据的保守性,从而建立一组新的分层结构LMI条件;严格证明了在采用相同概率区间划分的条件下,所得到的稳定性判据的保守性低于不考虑时滞概率分布的时变时滞分解法所得到的结果,并且分析和比较了两种方法的计算量.     

Distributed Computation Multi-agent System

This article addresses a formal model of a distributed computation multi-agent system. This model has evolved from the experimental research on using multi-agent systems as a ground for developing fuzzy cognitive maps. The main paper contribution is a distributed computation multi-agent system definition and mathematical formalization based on automata theory. This mathematical formalization is tested by developing distributed computation multi-agent systems for fuzzy cognitive maps and artificial neural networks – two typical distributed computation systems. Fuzzy cognitive maps are distributed computation systems used for qualitative modeling and behavior simulation, while artificial neural networks are used for modeling and simulating complex systems by creating a non-linear statistical data model. An artificial neural network encapsulates in its structure data patterns that are hidden in the data used to create the network. Both of these systems are well suited for formal model testing. We have used evolutionary incremental development as an agent design method which has shown to be a good approach to develop multi-agent systems according to the formal model of a distributed computation multi-agent system.     

Transition of interarrival time patterns between automated and manual configurations of assembly systems

The paradigm of hybrid automatic/manual assembly systems has recently been extended by reconfigurable systems that allow exchanging manual and automated production modules with minimum interruption of the system control and operation. However, both types of assembly systems exhibit different interarrival time patterns for layouts that employ asynchronous workpiece transport on tracks with multiple routes and loops. In this work, it has been shown analytically that for Gaussian processing time distributions the queue length follows heavy-tailed unimodal and bimodal distributions. Based on the resulting outlier probability, an analytical model for predicting the limits of allowable processing time variance for deterministic interarrival time models is proposed. This model is positively validated with simulation analysis by comparing different levels of processing time variance. It is concluded that established design practices such as cycle-time balancing and synchronization should be avoided in reconfigurable hybrid assembly system design because they introduce interarrival-time turbulence in the automated system.     

井下声波数据压缩系统中FIFO深度的研究

在现代井下声波数据实时无损压缩系统中,广泛采用异步FIFO来解决模块间异步时钟域同步的问题。为了在提高系统工作效率的同时节省硬件资源,FIFO深度选取问题就更加突出。提出了一种基于随机服务系统理论的异步FIFO模型,同时结合压缩系统中哈希桶深的概率分布特性,计算出了异~FIFO深度,从而为实时硬件压缩系统的时序设计提供了理论支撑。     

Delay-Insensitivity and Semi-Modularity

The study of asynchronous circuit behaviors in the presence of component and wire delays has received a great deal of attention. In this paper, we consider asynchronous circuits whose components can be any non-deterministic sequential machines of the Moore type, and describe a formal model for these circuits and their behaviors under the inertial delay model.We model an asynchronous circuit C by a network N of modules with delays associated with its components and/or wires. We compute the behavior of N assuming arbitrary inertial delays in the modules, and take this behavior to be correct. We define N to be strongly delay-insensitive if its behavior remains correct in the presence of arbitrary stray delays, where correctness is defined through the notion of observational equivalence (or bisimulation), one of the strongest forms of behavioral equivalence. We introduce the notion of quasi semi-modularity, which generalizes Muller's definition of semi-modularity to non-deterministic networks. We prove that a circuit, with all the wire delays taken into account, is strongly delay-intensitive if and only if its behavior is quasi semi-modular.     

多变量逆解耦自抗扰控制及其在精馏塔过程中的应用

化工生产是一类典型的多变量过程对象,该类对象具有时变性、耦合性、时滞性等特点,传统的单变量控制方法很难在此类系统中取得良好的控制效果.针对时变性,本文在假设对象模型未知的前提下,利用阶跃响应数据,研究了基于最小二乘的一阶、二阶时滞系统辨识方法.针对多变量系统存在耦合性的特点,采用逆解耦方法实现对象的解耦.再对解耦后的时滞子系统设计了自抗扰控制器.仿真实验中,以精馏塔的Wood-Berry模型和Ogunnaike-Ray模型为例,验证了算法的有效性.     

Microprocessor-based simulator of a variable time delay

This article outlines a method for the simulation of a pure time delay element in analogue simulation of dynamic systems using a microcomputer. The hardware of the simulator and the flowchart of its operation are illustrated and described. The main characteristics of the realized simulator, the I/O voltage range, the manually variable time delay, the sampling period and the time of operation are provided with suggested modifications for improved performance.     

Parallel simulations of multiprocessors

This paper describes the implementation and the performance of a synchronous, parallel discrete event simulation (SPaDES) method on two shared memory multiprocessors. The presented method aims at the efficient simulation of architectural designs for which the asynchronous PDES methods are less effective. A multiprocessor machine is simulated, and the performance achieved is compared to the performance of a parallel version of the centralized-time synchronous simulation method. The results show that the SPaDES method alleviates bottlenecks usually attributed to synchronous methods, and thus we are able to efficiently exploit most of the parallelism available in the simulation of synchronous architectural designs.     

基于变尺度变换减少Sigma点的粒子滤波算法研究

为了减少传统无味粒子滤波(Unscented particle filter, UPF) 算法的计算负担, 提出了最小斜度单形无味转换(Minimal skew simplex UT, MSSUT) 方法, 这种方法是用最小斜度无味卡尔曼滤波来产生粒子的重要性函数. 它不仅能够扩大重要性分布与系统状态的后验概率密度的重叠性, 而且能够通过减少Sigma 点来减少计算负担. 但是, 随着状态空间维数的增加, Sigma 点集的覆盖半径增大, 导致了Sigma 点集的聚集性变差. 辅助随机变量变尺度无味变换(Auxiliary random variable formulation of the scaled unscented transformation, ASUT) 能够克服Sigma 点集分布扩展的缺点. 所以, 提出了一种高维空间中改进的变尺度最小斜度无味粒子滤波(Scaled minimal skew simplex unscented particle filter, SMSSUPF) 算法. 仿真结果表明: 在高维状态空间中, 与传统的无味粒子滤波(UPF) 相比, 计算复杂度和计算负担显著减少. 与最小斜度无味粒子滤波(Minimal skew simplex unscented particle filter, MSSUPF) 相比, SMSSUPF 减少了系统噪声方差和测量噪声方差所带来的估计误差.     

DIVIDE: Distributed visual display of the execution of asynchronous, distributed algorithms on loosely coupled parallel processors

The issue of monitoring the execution of asynchronous, distributed algorithms on loosely coupled parallel processor systems is important for the purposes of (i) detecting inconsistencies and flaws in the algorithm; (ii) obtaining important performance parameters for the algorithm; and (iii) developing a conceptual understanding of the algorithm's behavior, for given input stimulus, through visualization. For a particular class of asynchronous distributed algorithms that may be characterized by independent and concurrent entities that execute asynchronously on multiple processors and interact with one another through explicit messages, information about the flow of messages and the activity of the processors may contribute significantly towards the conceptual understanding of the algorithm's behavior and the functional correctness of the implementation. The computation and subsequent display of important parameters, based upon the execution of the algorithm, is an important objective of DIVIDE. For instance, the mean and standard deviation values for the propagation delay of ATM cells between any two given Broadband-ISDN (BISDN) nodes in a simulation of BISDN network under stochastic input stimulus, as a function of time, are important clues to the degree of congestion in the Broadband-ISDN network. Although the execution of the algorithm typically generates high-resolution data, often, a coarse-level visual representation of the data may be useful in facilitating the conceptual understanding of the behavior of the algorithm. DIVIDE permits a user to specify a resolution less than that of the data from the execution of the algorithm, which is then utilized to coalesce the data appropriately. Given that this process requires significant computational power, for efficiency, DIVIDE distributes the overall task of visual display into a number of user-specified workstations that are configured as a loosely coupled parallel processor. DIVIDE has been implemented on a heterogeneous network of SUN Sparc 1+, Sparc 2, and 3/60 workstations, and performance measurements indicate significant improvement over that of a uniprocessor-based visual display.     

随机非线性动态系统数值模拟与性态分析

针对具有随机参数非线性系统和随机非线性系统的数值模拟与性态分析问题,提出将蒙特卡罗模拟办法与数值积分法相结合,建立了迭代积分算法求取随机非线性系统在不副随机序列作用下的数值解集,分析了计算误差．其次,利用数值解集的样本值进行解过程性态分析,建立了系统状态的概率分布、均方和矩函数的数值汁箅公式,实现了该类系统数值模拟分析的完整算法和程序流程设计．最后,通过两类典型示例系统的数值仿真结粜验证本文算法与流程的正确性和有效性．     

An Implementation of Constructive Synchronous Programs in POLIS

Design tools for embedded reactive systems commonly use a model of computation that employs both synchronous and asynchronous communication styles. We form a junction between these two with an implementation of synchronous languages and circuits (Esterel) on asynchronous networks (POLIS). We implement fact propagation, the key concept of synchronous constructive semantics, on an asynchronous non-deterministic network: POLIS nodes (CFSMs) save state locally to deduce facts, and the network globally propagates facts between them. The result is a correct implementation of the synchronous input/output behavior of the program. Our model is compositional, and thus permits implementations at various levels of granularity from one CFSM per circuit gate to one CFSM per circuit. This allows one to explore various tradeoffs between synchronous and asynchronous implementations.     

一种实现高速异步FIFO的FPGA方法

在跨时钟域传递数据的系统中,常采用异步FIFO（First In First Out,先进先出队列）口来缓冲传输的数据,以克服亚稳态产生的错误,保证数据的正确传输。但由于常规异步FIFO模块中的RAM存储器读写寻址指针常采用格雷码计数器以及“空满”控制逻辑的存在,将使通过这两个模块的信号通路延时对整个模块的工作频率造成制约。提出了一种在FPGA内实现高速异步FIFO的方法,该方法针对不可能产生满信号的高频系统,通过省略“满”信号产生模块和多余的存储器位深来简化常规的FIFO模块,而只保留“空”信号产生模块。仿真和综合设计结果表明,整个模块的工作频率得到一定提高。     

Stability of a class of switched stochastic nonlinear systems under asynchronous switching

The stability of a class of switched stochastic nonlinear retarded systems with asynchronous switching controller is investigated. By constructing a virtual switching signal and using the average dwell time approach incorporated with Razumikhin-type theorem, the sufficient criteria for pth moment exponential stability and global asymptotic stability in probability are given. It is shown that the stability of the asynchronous stochastic systems can be guaranteed provided that the average dwell time is sufficiently large and the mismatched time between the controller and the systems is sufficiently small. This result is then applied to a class of switched stochastic nonlinear delay systems where the controller is designed with both state and switching delays. A numerical example illustrates the effectiveness of the obtained results.     

Analysis of asynchronous polynomial root finding methods on adistributed memory multicomputer

We have studied various implementations of iterative polynomial root finding methods on a distributed memory multicomputer. These methods are based on the construction of a sequence of approximations that converge to the set of zeros. The synchronous version consists in sharing the computation of the next iterate among the processors and updating their data through a total exchange of their results. In order to decrease the communication cost, we introduce asynchronous versions. The computation of the next iterate is still shared among the processor, but the updating is done by using only nearest neighbor communications. We prove that under weak conditions, these asynchronous versions are still locally convergent, even if their convergence orders are reduced. We analyze the behavior of the asynchronous methods in function of their delay, the topology of the interconnection network, and the elementary computation and communication times. We have implemented and compared these methods on a hypercube multicomputer     

具有测量数据丢失的离散不确定时滞系统鲁棒Kalman滤波

研究了具有测量数据丢失的离散不确定时滞系统鲁棒Kalman滤波问题, 其中时延存在于系统状态和观测值中. 模型的不确定性通过在系统矩阵中引入随机参数扰动来表示, 测量数据丢失现象则通过一个满足Bernoulli分布且统计特性已知的随机变量来描述. 基于最小方差估计准则, 利用射影性质和递归射影公式得到一个新的滤波器设计方法, 并且保证了滤波器的维数与原系统相等. 与传统的状态增广方法相比, 当时延比较大时, 该方法可以有效降低计算量. 最后, 给出一个仿真例子说明所提方法的有效性.     

State‐Feedback Stabilization of Stochastic Nonlinear Systems with Time‐Varying Delay and Different Orders

This paper studies the problem of state feedback stabilization for a class of stochastic time‐varying delay nonlinear systems which are neither necessarily feedback linearizable nor affine in the control input. Based on the backstepping design method and the adding of a power integrator technique, a state feedback controller is constructed to ensure the origin of closed‐loop system is globally asymptotically stable in probability. The main design difficulty is how to deal with the different power orders, time‐varying delay and the nonsmooth system perturbations. The efficiency of the state feedback controller is demonstrated by a simulation example.     

Input–output method to fault detection for discrete-time fuzzy networked systems with time-varying delay and multiple packet losses

The fault detection (FD) problem for discrete-time fuzzy networked systems with time-varying delay and multiple packet losses is investigated in this paper. The communication links between the plant and the FD filter (FDF) are assumed to be imperfect, and the missing probability is governed by an individual random variable satisfying a certain probabilistic distribution over the interval [0 1]. The discrete-time delayed fuzzy networked system is first transformed into the form of interconnect ion of two subsystems by applying an input–output method and a two-term approximation approach, which are employed to approximate the time-varying delay. Our attention is focused on the design of fuzzy FDF (FFDF) such that, for all data missing conditions, the overall FD dynamics are input–output stable in mean square and preserves a guaranteed performance. Sufficient conditions are first established via H_∞ performance analysis for the existence of the desired FFDF; meanwhile, the corresponding solvability conditions for the desired FFDF gains are characterised in terms of the feasibility of a convex optimisation problem. Moreover, we show that the obtained criteria based on the input–output approach can also be established by applying the direct Lyapunov method to the original time-delay systems. Finally, simulation examples are provided to demonstrate the effectiveness of the proposed approaches.