A single server retrial queue with general retrial times and two-phase service

An M / G / 1 retrial queue with a first-come-first-served (FCFS) orbit, general retrial time, two-phase service and server breakdown is investigated in this paper. Customers are allowed to balk and renege at particular times. Assume that the customers who find the server busy are queued in the orbit in accordance with an FCFS discipline. All customers demand the first “essential” service, whereas only some of them demand the second “optional” service, and the second service is multioptional. During the service, the server is subject to breakdown and repair. Assume that the retrial time, the service time, and the repair time of the server are all arbitrarily distributed. By using the supplementary variables method, the authors obtain the steady-state solutions for both queueing and reliability measures of interest. This research is supported by the National Natural Science Foundation of China under Grant No. 10871020.     

Optimal policy for controlling two-server queueing systems with jockeying

This paper studies the optimal policy for joint control of admission, routing, service, and jockeying in a queueing system consisting of two exponential servers in parallel.Jobs arrive according to a Poisson process.Upon each arrival, an admission/routing decision is made, and the accepted job is routed to one of the two servers with each being associated with a queue.After each service completion, the servers have an option of serving a job from its own queue, serving a jockeying job from another queue, or staying idle.The system performance is inclusive of the revenues from accepted jobs, the costs of holding jobs in queues, the service costs and the job jockeying costs.To maximize the total expected discounted return, we formulate a Markov decision process(MDP) model for this system.The value iteration method is employed to characterize the optimal policy as a hedging point policy.Numerical studies verify the structure of the hedging point policy which is convenient for implementing control actions in practice.     

Optimal reinsurance and investment strategies for insurers with regime-switching and state-dependent utility function

This paper considers a proportional reinsurance-investment problem and an excess-of-loss reinsurance-investment problem for an insurer, where price processes of the risky assets and wealth process of the insurer are both described by Markovian regime switching. The target of the insurer is assumed to maximize the expected exponential utility from her terminal wealth with a state-dependent utility function. By employing the dynamic programming approach, the optimal value functions and the optimal reinsurance-investment strategies are derived. In addition, the impact of some parameters on the optimal strategies and the optimal value functions is analyzed, and lots of interesting results are discovered, such as the conclusion that excess-of-loss reinsurance is better than proportional reinsurance is not held in the regime-switching jump-diffusion model.     

Optimal control of an M/G/1 retrial queue with vacations

In this note, we consider an M/G/1 retrial queue with server vacations, when retrial times, service times and vacation times are arbitrary distributed. The distribution of the number of customers in the system in stationary regime is obtained in terms of generating function. Next, we give heavy traffic approximation of such distribution. We show that the system size can be decomposed into two random variables, one of which corresponds to the system size of the ordinary M/G/1 FIFO queue without vacation. Such a stochastic decomposition property is useful for the computation of performance measures of interest. Finally, we solve simple problems of optimal control of vacation and retrial policies.     

Reliability indices of discrete-time Geox/G/1 queueing system with unreliable service station and multiple adaptive delayed vacations

This paper considers the discrete-time Geo~x/G/1 queueing model with unreliable service station and multiple adaptive delayed vacations from the perspective of reliability research.Following problems will be discussed:1) The probability that the server is in a generalized busy period at time n;2) The probability that the service station is in failure at time n,i.e.,the transient unavailability of the service station,and the steady state unavailability of the service station;3) The expected number of service station failures during the time interval(0,n],and the steady state failure frequency of the service station;4) The expected number of service station breakdowns in a server’s generalized busy period.Finally,the authors demonstrate that some common discrete-time queueing models with unreliable service station are special cases of the model discussed in this paper.     

延迟启动-关闭型的N-策略M/G/1排队系统队长分布

研究服务台具有延迟启动和延迟关闭的N-策略M/G/1排队系统,利用全概率分解技术,导出了任意时刻t瞬态队长分布的Laplace变换的递推关系式,进一步得到稳态队长分布的递推式以及平稳队长分布的随机分解.最后进行了数值实验,并考察了稳态队长分布以及附加队长分布的统计性质.     

多重假期中以概率p进入的M/G/1可修排队系统

考虑在服务员假期中到达的顾客以概率p(0＜p≤1)进入系统的多重休假M/G/1可修排队系统,运用全概率分解技术和拉普拉斯变换,研究了服务台的下列可靠性指标:1)首次失效前的寿命分布;2)瞬时不可用度和稳态不可用度;3)在(0,t]时间内的平均失效次数.获得了服务台一系列的可靠性结果.     

Optimal closed-loop identification test design for internal model control

In this paper, optimal cloeed-loop test design for control is studied. The identified model is used for controller design. The control scheme used is internal model control (IMC) and the design constraint is the power of the process output or that of the reference signal. The measure of performance is the variance of the error between the output of the ideal closed-loop system (with the ideal controller) and that of the actual closed-loop system (with the controller computed from the identified model). Optimal spectrum formulae can be used to determine the PRBS signal in industrious identification.     

一类非线性广义系统最优控制及应用

利用Zubov方法和最优控制理论研究了非线性广义系统的最优控制问题.首先将非线性广义系统正则化为非线性正常系统,对其施加状态反馈控制,继而构造含有调节参数向量的性能指标,并由偏微分方程解得该性能指标;最后应用最优化理论求得最优调节参数向量,得到非线性广义系统最优控制律.将有关结论应用于Logistic 增长的SIS模型,给出消除该传染病的条件.     

Fuzzy controller design for networked control system with time-variant delays

1.INTRODUCTIONAs a system becomes more and more intelligent andflexible,the systemrequires more sensors,actuators,and controllers,which are often referred to as fielddevices.In most cases,these field devices requiresome type of electrical connection because they aredistributed over a certain area.Conventionally thesedevices are connected with point-to-point connec-tions,whichis not suitable any more for modern in-dustrial control systems,because the number of cableis proportional tothe squ…     

多个服务中心的服务网络设计与优化

为解决具有多个需求节点和多个服务中心的服务网络,如何在预算约束条件下设计与优化服务网络的服务中心配置,使得服务网络运营的总效率最高的决策问题,本文对多个服务中心的服务网络优化问题进行了提炼和描述,并构建了服务网络设计的优化模型,同时证明了该服务网络优化问题是一个NP-完全问题;进一步,针对优化模型的特点,设计了求解模型的混合拆分遗传算法,进行了大规模仿真实验并与传统的多目标遗传算法进行了比较,结果表明本文给出的算法具有较好的求解效率和效果;最后,通过例子说明了本文提出方法的潜在应用价值.     

一类非更新到达的两结点休假闭网络分析

以计算机系统实际应用为背景，提出了带MMPP(Markov-modulated Poisson process)到达的两结点休假闭网络。该模型也适用于带反馈的通讯信息系统和有限工位的自适应生产系统等。MMPP是较Erlang分布和PH分布等到达间隔更为广泛的一类马尔可夫到达，将其引进闭路休假排队系统在已有的文献中尚未见报道，因此，该研究无论从实际应用目的还是从理论研究的角度看都是十分有意义的。文中采用了相位分解原理和嵌入马尔可夫更新过程及带指数到达依态策略休假的两结点闭网络分析，求得了所述模型的稳态分布和循环时间。它是用开路模型已有结果来解决相应闭路系统问题的又一个尝试。     

Hybrid approach for fuzzy system design

A hybrid approach for fuzzy system design based on clustering and a kind of neurofuzzy networks is proposed. An unsupervised clustering technique is firstly used to determine the number of if-then fuzzy rules and generate an initial fuzzy rule base from the given input-output data. Then, a class of neurofuzzy networks is constructed and its weights are tuned so that the obtained fuzzy rule base has a high accuracy. Finally, two examples of function approximation problems are given to illustrate the effectiveness of the proposed approach.     

Optimal design of basic pulse waveforms for THSS UWB radio systems

1.INTRODUCTION Recently,therehasbeenagreatinterestinUWBra dioforfuturehighrateshort rangewirelesscommu nications[1～4].Forhighlyresolvingmultipathand generatingUWBsignalswithrelativelylowcomplexi ty,UWBradiosystemsusuallyuseTHSSimpulse trainwithPPMtocarrydatainformation[5,6].That iswhyitissometimescalledimpulseradio(IR).The essenceofUWBradioisthatitdoesnotuseasinu soidalcarrierbutinsteadcommunicateswithaTHSS basebandsignalcomposedofsubnanosecondpulses withPPM.Thatis,UWBra…     

An Optimal Replacement Policy for a System with Finite Spares

1.INTnODUCTIoNPlannedreplacementisanimportantmethodtoensureasystem'ssafetyandkeepitatahighlevelofreliability.Thereplacementproblemhasbeengivenconsiderableattentionsandthereissubstantialliteratureonit,e.g.,references[1~6].Sofar,themostmodelshavenottakenaccountofthepossiblelackofspareunitbymakinganassumptionofsufficientspares.Butinpractice,thenumberofsparesislimitedandoptimalreplacementpolicyisevidentlyrelativetospareparts.Thereference[6]discussedtheproblemoflimitedspares)andproposedanoptimu…     

Nonparametric estimation for hazard rate monotonously decreasing system

1.INTRODUCTION Estimationofdensityandhazardrateisveryimpor tanttothereliabilityanalysis.Formanysystems,the hazardrateisdecreasingmonotonously,thushazard rateestimationforhazardratemonotonouslydecreas ingsystemisespeciallyimportant.Generally,inor dertoestimatehazardrateordensity,peopleassume thatthedataaredrawnfromoneofaknownpara metricfamilyofdistributions,andthenestimatethe parametersbyleastsquarefitormaximumlikelihood estimation.Butthebasicassumptionsaresometimes unsound,anddisputed…     

基于System C的星载计算机系统设计

分析了小卫星星载计算机系统的公共需求及其应用的特殊性,给出了典型小卫星星载计算机系统的通用体系结构;提出了基于System C的星载计算机系统的设计方法。通过与传统的星载计算机系统设计方法的对比,提出的基于System C的设计方法可使星载计算机系统的研发周期缩短,设计质量获得较大的提升。同时结合实际工程经验,给出了星载计算机系统软硬件协同设计的基本步骤。     

A SUSTAINABLE PLATFORM FOR E-SERVICE SYSTEM DESIGN

1. Introduction We all know that service business is a verycomplex and dynamic system, which meansthat many elusive and interrelated componentsor objects are involved in the service business,and they are dynamically interrelated.Accord…     

统计平衡状态下复合系统的维修理论及其优化设计

为防止产品性能退化或为了降低产品失效的概论,在统计平衡状态下讨论了复合系统(串联-并联系统,并联-串联系统,表决-串联系统,旁联-串联系统)的预防维修措施的维修理论,并给出了系统中单元的冗余数及维修人员数的最优设计方法。列举多个算例,对这些算例进行比较表明,所提出的整数规划算法非常有效。