状态相关闭排队网络中的性能指标灵敏度公式

本文通过研究一类Ｍａｒｋｏｖ过程在无穷小矩阵的参数摄动下稳态性能指标的灵敏度,运用无穷小矩阵的群逆,实现矩阵和势能这三个描述稳定性能指标灵敏度的等价量,给出了状态相关闭排队网络在参数摄动下的稳态性能指标灵敏度公式,这些结果可直接用于排队网络的控制和优化。     

闭排队网络基于并行仿真的灵敏度估计和优化算法

基于Markov性能势理论，对一类闭排队网络的灵敏度估计和优化，建立了一种行之有效的并行仿真算法。采用公共随机数，使所有的处理器使用相同的样本轨道，以减少各个处理器之间的通讯时间。在一台SPMD并行计算机上的仿真实例表明，该并行仿真算法对于闭排队网络的优化能显著地提高运算速度。     

基于仿真的可重入排队网络灵敏度分析

由马尔可夫链的Poisson方程推导了系统平均费用型品质指标对参数的导数公式,并给出了相应的估计算法。对可重入排队系统建立马尔可夫模型,通过仿真单个样本轨迹,应用给出的算法求出系统品质对参数的灵敏度,并分析了某些优先级调度策略的鲁棒性。仿真结果证明了该算法的实用性和有效性。     

Fork-Join排队网络建模与分析的研究进展

本文综述了近年来对一类特殊的离散事件动态系统——Fork-Join排队网络的研究进展。全文主要包括三部分:首先给出Fork-Join网络产生的实际背景及其精确的数学描述;其次,介绍已取得的主要结果及其所采用的方法;最后提出一些值得研究的问题。     

一类受控闭排队网络基于性能势的最优性方程

研究一类受控闭排队网络系统的性能优化问题. 文章引进了两个基本概念: 折扣代价α 性能势和平均代价性能势, 并且讨论了这两个性能势之间的一个关系式. 在一般的假设条件下, 我们应用性能势的基本性质直接建立了无限时间水平平均代价模型的最优性方程, 并且证明了在紧致集上最优解的存在性. 最后给出了一个策略优化的迭代算法并通过一个实际算例以说明该算法的效果.     

基于排队网络的网络服务器性能分析与优化

针对网络服务器在用户数量和状态相对复杂情况下无法对服务器性能进行有效分析的问题,提出了一种基于排队网络的服务器性能分析方法。该方法可以有效降低时间复杂度和空间复杂度,使服务器性能分析更加精确,效率更高。实验结果表明,利用该方法对服务器性能进行建模和分析,并根据分析结果对服务器程序进行优化,可以达到合理利用系统资源、提高服务器性能的要求。     

连续系统中二次型性能函数对系统参数灵敏度的计算

本文给出了在连续系统中计算二次型性能函数对系统参数灵敏度的一般方法,结果归结为求解两个对偶的李雅普诺夫方程。同时给出了不同控制器结构时的具体算法。对于随机系统,也给出了相应的计算方法。最后举例说明本文结果在系统分析中的应用。     

基于分层排队网络模型的分布式系统性能评价

关于并发或分布式系统的性台匕评价是一个广泛研究的课题,提供有效的数学理论工具、直观的模型描述方法和有效的模型分析方法,是系统性能评价所面临的关键问题。传统的性能模型——排队网络模型已很难分析这样复杂的系统,分层排队网络（Layered Queueing Net,LQN）模型是排队网络模型的扩展,可以用来分析相互依赖任务间的冲突。介绍了分层排队网络模型的原理及研究现状,并以DBMS为例,建立了DBMS的分层排队网络模型。     

基于排队网络的容量分析与模拟

客户机／服务器模型（Client/Server)是当前计算机网络系统应用最广泛的模型。为了提高系统的服务等级（Degree of Servier)，找到制约系统性能的瓶颈，对系统进行分析以及模拟就显得十分的重要。基于排队网络建立了客户机／服务器模型。介绍了排队网络的MVA算法，并提出了一个近似的算法。并且，结合一个实例介绍了如何进行系统性能分析；最后，用离散事件模拟工具（Discrete Events Simulation Tool)OMNET进行了模拟，验证了分析的可靠性。     

New Linear Program Performance Bounds for Closed Queueing Networks

We develop new linear program performance bounds for closed reentrantqueueing networks based on an inequality relaxation of the averagecost equation. The approach exploits the fact that the transitionprobabilities under certain policies of closed queueing networksare invariant within certain regions of the state space. Thisinvariance suggests the use of a piecewise quadratic functionas a surrogate for the differential cost function. The linearprogramming throughput bounds obtained are provably tighter thanpreviously known bounds at the cost of increased computationalcomplexity. Functional throughput bounds parameterized by thefixed customer population N are obtained, alongwith a bound on the limiting throughput as N + .We show that one may obtain reduced complexity bounds while stillretaining superiority.     

Modeling Truck–Shovel Systems as Closed Queueing Network with Multiple Job Classes

In this paper an analytical method is proposed to model the truck–shovel system as a closed queueing network with multiple job classes. This approach would provide the capability of estimating system performance measures (mine throughput, mean number of trucks, mean waiting time etc.) for planning purposes when the truck fleet is not necessarily composed of identical trucks. A computational study is presented to show how choosing different types of trucks affect the production level in a truck–shovel system. Mean Value Analysis (MVA) approach is used to compute all performance measures of the truck–shovel system.     

Synthesis of Closed Queueing Networks with Several Classes of Messages on the Basis of Their Optimization and Balancing

The optimization and balancing problems formulated in the author's previous works are theoretically investigated for queueing networks with several classes of messages. The necessary and sufficient conditions of the global optimal solution of these problems are obtained. It is shown that the method of Lagrangian multipliers can be used in solving them.     

一种计算性能指标对路径概率灵敏性的新方法

本文提出了应用全状态摄动分析直接计算对路径概率的灵敏性,推导了路径变化时摄动的产生规则,给出了两个数值例子.实验结果验证了这一方法的有效性和准确性,     

一种用于异步流水线环性能分析的排队网络近似分析算法

异步电路的性能评测一直是异步电路设计技术研究的难点所在。本文提出了异步流水线环的一种排队网络近似分析算法。首先将异步流水线环建模为闭合阻塞排队网络,再使用近似分析算法分析阻塞排队网络的性能,包括吞吐率、响应时间等,进而得到异步流水线的吞吐率、周期时间和延迟等性能参数。通过将本文算法的计算结果和数值计算得到
的精确结果进行比较,证明了该算法的正确性和有效性。     

Fork—Join排队网络的建模与稳定性

本文利用极大代数方法，建立了一类Ｆｏｒｋ—Ｊｏｉｎ排队网络的线性状态方程，分析了系统的稳定性。     

First and Second Derivative Estimators for Closed Jackson-Like Queueing Networks Using Perturbation Analysis Techniques

We consider a closed Jackson—like queueing network with arbitrary service time distributions and derive an unbiased second derivative estimator of the throughput over N customers served at some node with respect to a parameter of the service distribution at that node. Our approach is based on observing a single sample path of this system, and evaluating all second-order effects on interdeparture times as a result of the parameter perturbation. We then define an estimator as a conditional expectation over appropriate observable quantities, as in Smoothed Perturbation Analysis (SPA). This process recovers the first derivative estimator along the way (which can also be derived using other techniques), and gives new insights into event order change phenomena which are of higher order, and on the type of sample path information we need to condition on for higher-order derivative estimation. Despite the complexity of the analysis, the final algorithm we obtain is relatively simple. Our estimators can be used in conjunction with other techniques to obtain rational approximations of the entire throughput response surface as a function of system parameters.