Robust Feedback Control of a Single Server Queueing System

This paper extends previous work of Ball et al. [BDKY] to control of a model of a simple queueing server. There are n queues of customers to be served by a single server who can service only one queue at a time. Each queue is subject to an unknown arrival rate, called a “disturbance” in accord with standard usage from H _∞ theory. An H _∞-type performance criterion is formulated. The resulting control problem has several novel features distinguishing it from the standard smooth case already studied in the control literature: the presence of constraining dynamics on the boundary of the state space to ensure the physical property that queue lengths remain nonnegative, and jump discontinuities in any nonconstant state-feedback law caused by the finiteness of the admissible control set (choice of queue to be served). We arrive at the solution to the appropriate Hamilton–Jacobi equation via an analogue of the stable invariant manifold for the associated Hamiltonian flow (as was done by van der Schaft for the smooth case) and relate this solution to the (lower) value of a restricted differential game, similar to that formulated by Soravia for problems without constraining dynamics. An additional example is included which shows that the projection dynamics used to maintain nonnegativity of the state variables must be handled carefully in more general models involving interactions among the different queues. Primary motivation comes from the application to traffic signal control. Other application areas, such as manufacturing systems and computer networks, are mentioned. Date received: August 14, 1998. Date revised: May 17, 1999.     

Analysis of the M/G/1 queue with discriminatory random order service policy

We consider an M/G/1 queue with different classes of customers and discriminatory random order service (DROS) discipline. The DROS discipline generalizes the random order service (ROS) discipline: when the server selects a customer to serve, all customers waiting in the system have the same selection probability under ROS discipline, whereas customers belonging to different classes may have different selection probabilities under DROS discipline. For the M/G/1 queue with DROS discipline, we derive equations for the joint queue length distributions and for the waiting time distributions of each class. We also obtain the moments of the queue lengths and the waiting time of each class. Numerical results are given to illustrate our results.     

可修排队系统GI/G(M/G)/1的可靠性分析

利用更新过程理论和向量马氏过程方法全面考察了可修排队系统GI/G(M/G)/1的结构,得到了所有感兴趣的指标,并证明了服务台的可靠性指标只与系统的忙期、闲期和忙期循环时间有关.     

Performance of the MAP/G/1 Queue Under the Dyadic Control of Workload and Server Idleness

This paper studies the steady-state queue length process of the MAP/G/1 queue under the dyadic control of the D-policy and multiple server vacations. We derive the probability generating function of the queue length and the mean queue length. We then present computational experiences and compare the MAP queue with the Poisson queue.

基于客户端/服务器模式的远程测控系统

针对外场恶劣的试验条件及光电测控系统通信多样化的问题,介绍了以以太网为通信网络的分布式测控系统,基于客户端/服务器模式进行远程控制的方法。系统采用Winsock编程和多线程并发技术,以异步通信方式完成系统控制命令和测量数据的传输。通过在专用的工具软件中加入远程控制命令,数据处理中心实现了远程控制各测量站测量试验,提高了光电测控系统的工作效率和测量数据的时效性,大大降低了外场试验的危险性。     

Performance Analysis of a Client–Server System Using Queueing Networks: A Case Study

Queueing networks have been widely used to evaluation performance of mainframe computer systems. In contrast, few results have been reported for modern open systems, so it was not clear whether queueing networks are useful for modern systems or not. We think this situation has partly been due to lack of handy evaluation tools. This paper presents tow tools that we developed to evaluate open system performance. On is a measuring tool that is capable of accurately obtaining the service times of system resources requested by an application transaction. The other is an estimating tool which calculates various performance measures based on queueing network models. This paper also describes a case study in which the performance of a medium-sized UNIX client–server system (up to 24 clients) is estimated using the tools and these estimates are then compared with experimental results. The estimates closely agree with the measured results and are accurate enough for practical applications. Based on this, we conclude that queueing network models are also useful for modern systems.     

可修排队系统Mx/G (M/H)1的瞬态解

本文研究一个典型的批到达可修排队系统＾ｘ／（／）１．记号（／）表服务台寿命服从指数分布，而其修理时间为一连续型分布。利用向量马氏过程方法，我们得到了它的瞬态解。特别是发现了服务台的可靠性指标仅依赖于可修排队系统的空闲概率，或等价地仅依赖于它的忙期和忙循环。     

网格服务器性能优化系统研究与实现

为了提高网格服务器的性能，研究和设计了基于分配器的网格服务器性能优化系统，并实现了一个原型系统——集群式网格服务器．该原型系统能够集成多个网格处理服务器的处理能力，提供一个单一映象的网格服务．在这些服务器上实现负载平衡，并通过分配器统一对外提供网格服务．测试并分析了CGSS系统的性能测试结果．测试结果表明，基于分配器的性能优化能够显著的提高网格服务器系统的性能．     

Asymptotic Analysis of an Retrial Queueing System M|M|1 with Collisions and Impatient Calls

We consider a single-line RQ-system with collisions with Poisson arrival process; the servicing time and time delay of calls on the orbit have exponential distribution laws. Each call in orbit has the “impatience” property, that is, it can leave the system after a random time. The problem is to find the stationary distribution of the number of calls on the orbit in the system under consideration. We construct Kolmogorov equations for the distribution of state probabilities in the system in steady-state mode. To find the final probabilities, we propose a numerical algorithm and an asymptotic analysis method under the assumption of a long delay and high patience of calls in orbit. We show that the number of calls in orbit is asymptotically normal. Based on this numerical analysis, we determine the range of applicability of our asymptotic results.     

基于以太网和嵌入式Web服务器的监控系统设计

针对监控系统采用集中查询服务器存在布线较复杂、系统可靠性较低、可能出现网络拥塞等问题,提出了基于以太网和嵌入式Web服务器的监控系统设计方案,详细介绍了该系统的硬件电路扩展和软件架构设计。该系统通过采用嵌入式Web服务器使煤矿生产系统的每个监控子系统均拥有自己独立的Web服务器,采用以太网对监控子系统组网,并通过适当的网关将现场监控网络接入煤矿办公自动化局域网,使现场监控网络和办公自动化网络融为一体,管理层在PC上通过浏览器即可实时监控生产现场的信息。     

基于SQL Server的硬件控制系统设计与实现

针对目前主流商业数据库引擎并不具有工业总线通讯和硬件控制的功能,由此造成了工业现场部署的困难和复杂度问题,文中提出一种基于SQL Server进行硬件控制的方法。本方法利用SQL Server扩展存储过程的特性,通过在存储过程中封装对CAN总线系统中驱动程序接口的调用,来实现SQLServer对硬件系统的访问控制,把SQL Server从传统的关系数据库应用领域拓展到了数据库管理和硬件控制应用相结合的场合。工程实践表明,本方法为使用单位节约了大量硬件开销,减少了控制总线的设计和部署的困难。     

Optimal management for infinite capacity N-policy M/G/1 queue with a removable service station

In this article, we consider an infinite capacity N-policy M/G/1 queueing system with a single removable server. Poisson arrivals and general distribution service times are assumed. The server is controllable that may be turned on at arrival epochs or off at service completion epochs. We apply a differential technique to study system sensitivity, which examines the effect of different system input parameters on the system. A cost model for infinite capacity queueing system under steady-state condition is developed, to determine the optimal management policy at minimum cost. Analytical results for sensitivity analysis are derived. We also provide extensive numerical computations to illustrate the analytical sensitivity properties obtained. Finally, an application example is presented to demonstrate how the model could be used in real applications to obtain the optimal management policy.     

基于IIC和云服务器的智能家居控制系统设计

智能家居普遍采用无线通信技术对家居进行互联,不同的通信方法对智能家居系统的稳定性、便捷性、可靠性有很大的影响;针对智能家居的访问方式,通过对比不同的无线通信技术,选择合适的技术运用在智能家居系统的设计中,实现局域网和广域网两种访问方式;在无线传输的智能家居基础上,使用IIC总线进行功能扩展,使用云服务器来替代传统计算机服务器,增加了系统的灵活性和手机访问的快捷性,更好地实现家庭住宅管理与监测,为我们平时的生活提供便利和保护。     

基于Jini技术的Web服务器集群的研究与设计

通过对Jini技术和Web服务器集群的工作原理的介绍,分析了Jini构造Web服务器集群的可行性和具有的优势;提出了基于Jini技术构建Web服务器集群的实现模型,并给出了在构建Web服务器集群的过程中实现高可用性、负载平衡的解决方案。     

基于Jini技术的Web服务器集群的研究与设计

通过对Jini技术和Web服务器集群的工作原理的介绍,分析了Jini构造Web服务器集群的可行性和具有的优势;提出了基于Jini技术构建Web服务器集群的实现模型,并给出了在构建Web服务器集群的过程中实现高可用性、负载平衡的解决方案。     

工控系统中嵌入式Web服务器的设计与实现

针对传统Web技术路线方案用于构造工控系统中Web服务器存在的困难,提出应用嵌入式技术开发工控系统中嵌入式Web服务器的基本思想。文章结合工控产品开发实例,介绍了嵌入式Web服务器的功能,给出了系统基于三层B/S结构的瘦Web服务器体系结构,详细阐述了嵌入式Web服务器实现的一些关键技术。工控系统基于嵌入式Web服务器的远程监控维护方式将有效降低监控运行维护成本、提高监控运行维护效率,因而具有很大的应用前景和推广价值。     

采用B/S结构的计算机网络考试和管理系统

采用B／S结构的计算机网络考试和管理系统，以网络的管理理念和方法，系统的设计模型、操作试题、在线考试模式的设计思想，使系统运行具有切实的可行性。     

M/G/1排队网络系统性能研究

本论文以单一路由器(服务器)为例,从最原始的队列理论出发,探讨具有容量C的M/G/1队列模型的系统平均时延、系统稳态下的报文(用户)平均值、以及时延等问题。并对报文(用户)的服务质量需求作了详尽的数学推导。     

Analysis of Queues under Batch Service in an M/G/1 System in a Random Environment

A queue system with batch service is investigated. The batch size depends on the state both of the system and the state of some random environment. The server state changes under the action of the random environment. When the system is empty, a birth-death process acts as the random environment, whereas when the system is busy the random environment is disregarded and affects only the initial service probabilistic characteristics (in this sense, the random environment in the busy state can be regarded as arbitrary). An analytical model of the system is constructed and studied in terms Laplace (Laplace–Stieltjes) images. The generating function of the queue length is derived.