Optimal Control for a System on a Unit Simplex in Infinite Time

Optimal control for a semilinear system of first-order partial differential equations in infinite time is studied. The values of control variables belong to a finite-dimensional unit simplex at every instant at every point of the space. Necessary and sufficient conditions for the quality criterion of optimal control to be absolutely maximal are formulated.     

XMPP协议在Android即时通讯系统中的应用

即时通讯是一种基于互联网的网络应用,目前很多即时通讯系统,如MSN,QQ等,但由于使用了不同的协议,各个系统之间不能互联。可扩展消息与存在协议（XMPP）是即时通讯系统通信协议的标准,该文提出一种基于XMPP协议的即时通讯系统方案,并基于Android平台设计实现了即时通讯客户端,有效的解决了即时通讯系统中通信不畅的问题,并为其他类型智能平台间的即时通信提出一种可参考的解决方案。     

A numerical sufficiency test for the asymptotic stability of linear time-varying systems

A numerical sufficiency test for the asymptotic stability of linear time-varying Hurwitz systems is proposed. The algorithmic procedure constructs a bounding tube in which the state is guaranteed to stay. The continuous-time system is evaluated at discrete time instants, for which successive quadratic Lyapunov functions are generated. The tube is constructed based on: (i) a conservative estimate of the state evolution, from a discrete time instant to the next, obtained from the corresponding Lyapunov function, and (ii) re-evaluation of the tube diameter at each discrete time instant to account for variations in the plant matrix. The numerical test is illustrated in simulation via both a stable and an unstable system.     

Constrained motion planning of nonholonomic systems

This paper addresses the constrained motion planning problem for nonholonomic systems represented by driftless control systems with output. The problem consists in defining a control function driving the system output to a desirable point at a given time instant, whereas state and control variables remain over the control horizon within prescribed bounds. The state and control constraints are handled by extending the control system with a pair of state equations driven by the violation of constraints, and adding regularizing perturbations. For the regularized system a Jacobian motion planning algorithm is designed, called imbalanced. Solutions of example constrained motion planning problems for the rolling ball illustrate the theoretical concepts.     

Analysis of the busy period in threshold control system

Consideration was given to the controllable Markov queuing system with nonhomogeneous servers and threshold policy of server activation depending on the queue length. By the busy period is meant the time interval between the instant of customer arrival to the empty system and the instant of service completion when the system again becomes free. The system busy period and the number of serviced customers were analyzed. Recurrent relations for the distribution density in terms of the Laplace transform and generating function, as well as formulas for calculation of the corresponding arbitrary-order moments, were obtained.     

On solving a maximin reliability estimation problem by selection of the instant for standby switching-on

The apparatus of duel situations with time instant selection was used to consider certain examples of analytical determination of the maximin of discontinuous criterion which characterizes the probability of maintaining system serviceability through selection of the optimal instant for activation of the redundant unit. A certain generalization to the problem of seeking the maximin of discontinuous criterion was also presented.     

Saddle point MPC approach to nonlinear robust sampled-data control problem

This paper presents a robust nonlinear model predictive control strategy to consider the control of systems described by nonlinear ordinary differential equation in a sampled-data framework. The optimal couple controldisturbances is calculated as a time continuous function at each sampling instant by solving a saddle point problem. Using this controller, it is proved that the system is ultimately bounded and satisfies an exponential stability property at each sampling instants. To validate the efficiency of our approach, the presented methodology is illustrated on a cart, spring and damper example.     

被动目标定位系统观测平台的最优机动轨迹

对仅有方位量测的被动目标定位中观测平台最优机动轨迹问题进行了探讨.在最大化Fisher信息阵 (FIM)行列式指标下给出了当前时刻一种新的机动控制策略,从理论上证明了最优机动轨线有且仅有2支,并给出了最优机动策略和最优机动轨线方程;它的特点是对任意时刻均为最优,而不仅仅在观测时间的末端,几何直观描述了机动控制序列的可执行性;与最大化方位变化率下观测平台最优机动轨线相比较,本文的机动策略兼顾了距离和方位2个因素的影响,可看成是对距离信息和方位信息之间的折中.数字仿真表明,与传统方法比较,提出的新机动策略能获得更大的信息.     

Error variance-constrained ℋ∞ filtering for a class of nonlinear stochastic systems with degraded measurements: the finite horizon case

This article is concerned with the robust ?_∞ filtering problem for a class of time-varying nonlinear stochastic systems with error variance constraint. The stochastic nonlinearities considered are quite general, which contain several well-studied stochastic nonlinear systems as special cases. The purpose of the filtering problem is to design a filter which is capable of achieving the pre-specified ?_∞ performance and meanwhile guaranteeing a minimised upper-bounded on the filtering error variance. By means of the adjoint system method, a necessary and sufficient condition for satisfying the ?_∞ constraint is first given, expressed as a forward Riccati-like difference equation. Then an upper-bound on the variance of filtering error system is given, guaranteeing the error variance is not more than a certain value at each sampling instant. The existence condition for the desired filter is established, in terms of the feasibility of a set of difference Riccati-like equations, which can be solved forward in time, hence is suitable for online computation. A numerical example is presented finally to show the effectiveness and applicability of the proposed method.     

Moving horizon control of nonlinear systems with input saturation,disturbances and plant uncertainty

We present a moving horizon feedback system, based on constrained optimal control algorithms, for nonlinear plants with input saturation, disturbances and plant uncertainty. The system is a non-conventional sampled-data system: its sampling periods vary from sampling instant to sampling instant, and the control during the sampling time is not constant, but determined by the solution of an open loop optimal control problem. We show that the proposed moving horizon control system is robustly stable and is capable of attenuating L∞ bounded disturbances.     

基于AT89S8252单片机的汽车瞬时燃油油量检测系统的设计

介绍了以AT89S8252单片机为核心的汽车瞬时燃油测量检测系统,该系统利用汽车喷油脉冲计算瞬时喷油量,并且具有油箱油量、瞬时油耗、百公里油耗等实时显示功能.     

面向流式数据处理系统的高效故障恢复方法

针对流式数据处理系统Flink无法高效处理单点故障的问题,提出了一种基于增量状态和备份的故障容错系统Flink+。首先,提前建立备份算子和数据通路;然后,对数据流图中的输出数据进行缓存,必要时使用磁盘;其次,在系统快照时进行任务状态同步;最后,在系统故障时使用备份任务和缓存的数据恢复计算。在系统实验测试中,Flink+在无故障运行时没有显著增加额外容错开销;而在单机和分布式环境下处理单点故障时,与Flink系统相比,所提系统在单机8任务并行度下故障恢复时间减少了96.98%,在分布式16任务并行度下故障恢复时间减少了88.75%。实验结果表明,增量状态和备份方法一起使用可以有效减少流式系统单点故障的恢复时间,增强系统的鲁棒性。     

A new method for the control of discrete nonlinear dynamic systems using neural networks

A new controller design method for nonaffine nonlinear dynamic systems is presented in this paper. An identified neural network model of the nonlinear plant is used in the proposed method. The method is based on a new control law that is developed for any discrete deterministic time-invariant nonlinear dynamic system in a subregion Psi(x), of an asymptotically stable equilibrium point of the plant. The performance of the control law is not necessarily dependent on the distance between the current state of the plant and the equilibrium state if the nonlinear dynamic system satisfies some mild requirements in Psi(x). The control law is simple to implement and is based on a novel linearization of the input-output model of the plant at each instant in time. It can be used to control both minimum phase and nonminimum phase nonaffine nonlinear plants. Extensive empirical studies have confirmed that the control law can be used to control a relatively general class of highly nonlinear multiinput-multioutput (MIMO) plants.     

New Formulation of Dynamic Output Feedback Robust Model Predictive Control with Guaranteed Quadratic Boundedness

The dynamic output feedback robust model predictive controller for a system with both polytopic uncertainty and bounded disturbance is addressed in this paper. This controller utilizes a main optimization problem to find the control law and a simple auxiliary optimization problem to refresh the bounds on the true state. The main optimization problem, which is not necessarily solved at each sampling instant, achieves the near‐optimal solution. The auxiliary optimization, which is solved at each sampling instant, is followed with a simple criterion which determines whether or not to solve the main optimization problem at the next sampling time. By applying the proposed method, the augmented state of the closed‐loop system is guaranteed to converge to the neighborhood of the equilibrium point.     

基于MQTT协议的即时消息业务设计与实现

近年来,宽带接入技术正以十分惊人的速度发展.与此同时,移动互联网技术也日益成熟,即时消息业务已成为移动互联时代的应用热点.在互联网中XMPP和SIMPLE被广泛使用,但其并不能很好的适用于移动互联网.采用发布/订阅模型的MQTT协议是一种轻量级的消息传输协议,具有低功耗、节省流量和可扩展性强的优点.本文首先分析了XMPP和SIMPLE协议的不足之处,研究了MQTT协议的消息格式以及协议的使用方式,之后对即时消息业务进行了设计和实现.并在功能和性能上进行了相关的测试和分析.     

基于B／S和C／S的即时通信系统

为了在B／S下实现即时通信,提出一个适合于B／S和C／S的即时通信框架,选择Aiax,Flash作为客户端技术,实现一套即时通信系统。该系统克服以往C／S即时通信软件无法在B／S系统中应用的缺点,在基于B／S,C／S的系统间实现统一通信。     

Guaranteed detection of an imbalance instant of the GARCH-process

A detection instant problem of the GARCH-process parametric change with random noise distribution is studied. A sequential procedure of imbalance instant detection, where a decision of change existence is made at a given instant of time after the accumulation of given distinctions between possible process models, is suggested. Formulas for procedure characteristics calculation are developed, asymptotic qualities of the procedure are studied. Model estimated values are presented.     

基于群决策考虑属性效用一致性的DEA他评交叉效率公共权重排序法

针对一类主从式异构线性网络化多智能体系统,考虑每个智能体的反馈通道和前向通道中存在随机网络诱导时延和数据包丢失问题,采用预测控制方法,提出一种基于观测器的网络化多智能体协同输出跟踪控制方案.在该方案中,主智能体在每一时刻基于自身滞后输出和系统参考信号,计算一组控制预测序列和输出预测序列,前者用以主动补偿主智能体控制回路中的随机网络诱导时延和数据包丢失,后者被发往从智能体;从智能体在每一时刻基于主智能体发送过来的输出预测序列和自身滞后输出,计算一组控制预测序列,用以主动补偿从智能体控制回路中的随机网络诱导时延和数据包丢失;随后推导闭环网络化多智能体控制系统的稳定性,并通过实验验证该方案的有效性和可行性.     

Finite-horizon ℋ 2/ℋ ∞ control for a class of nonlinear Markovian jump systems with probabilistic sensor failures

This article is concerned with the mixed ?₂/?_∞ control problem over a finite horizon for a class of nonlinear Markovian jump systems with both stochastic nonlinearities and probabilistic sensor failures. The stochastic nonlinearities described by statistical means could cover several types of well-studied nonlinearities, and the failure probability for each sensor is governed by an individual random variable satisfying a certain probability distribution over a given interval. The purpose of the addressed problem is to design state feedback controllers such that the closed-loop system achieves the expected ?₂ performance requirement with a guaranteed ?_∞ disturbance attenuation level. The solvability of the addressed control problem is expressed as the feasibility of certain coupled matrix equations. The controller gain at each time instant k can be obtained by solving the corresponding set of matrix equations. A numerical example is given to illustrate the effectiveness and applicability of the proposed algorithm.     

Robust analysis for improvement of vowel onset point detection under noisy conditions

Vowel onset point (VOP) is the instant of time at which the vowel region starts in a speech signal. The VOPs are used as anchor points to design various speech based systems. Different algorithms exist in the literature to identify the occurrences of vowels in continuous spoken utterances. The algorithm based on combined evidences derived from source excitation, spectral peaks and modulation spectrum have been used as a baseline system for the present study. The baseline system provides a satisfactory level of performance under clean data condition. However under noisy data condition the performance of the previous system may be improved further by additional pre-processing of the raw speech data and post-processing the detected VOPs. In this paper we propose to use the speech enhancement techniques as pre-processing module to remove the noise from the speech data under different noisy conditions. The pre-processed speech data is then passed through the baseline system to detect the VOPs. It has been observed that there exist several spurious VOPs at the output of the baseline system. We propose to use a post-processing module based on average signal-to-noise ratio and information derived from the glottal closure instant to remove the spurious VOPs. The experiments were carried out on clean, artificially injected noisy, and data collected from the practical noisy environments. The results suggest that the proposed system using pre-processing and post-processing modules is robust and shows an improvement of 28–35 % over the existing baseline system by removing the spurious VOPs under different noisy conditions.