具有两类平行顾客的M/M/1重试排队系统均衡策略研究

本文研究具有两类平行顾客且服务台可靠的M/M/1重试排队系统的均衡策略.在该排队系统中,两类顾客平行到达,并服从不同参数的负指数分布.当顾客进入系统时,若观察到服务台为空,将立刻开始服务;若观察到服务台处于忙期,则进入重试空间等待重试.在完全可见和几乎可见两种情形下,基于“收益-成本”理论提出合理的效用函数并对两类平行顾客进行均衡分析.此外,建立单位时间的社会收益函数,给出最优社会效益分析.最后运用数值分析直观地表示出随着系统参数的改变,顾客行为策略的变化情况.     

带有N策略的不可靠重试队列的均衡策略分析

本文提出带有N策略和不可靠服务台且拥有恒定重试率的M/M/1排队系统,并研究了关于它的顾客策略行为和社会最优问题.在服务台前没有等待空间,如果顾客到达时发现服务台处于繁忙状态,则他要么选择加入轨道,要么选择离开系统.当服务台服务完一名顾客以后,他会按照恒定重试率和FCFS原则从轨道中选择重试顾客.当系统变空时,服务台会关闭直到轨道中的顾客数达到给定的阈值.假设顾客到达系统时会根据已知的信息和线性收支结构判断是否加入系统,我们得到了服务台处于不同状态下顾客的均衡到达率,并且发现该系统中到达顾客存在拥挤偏好(FTC)情形和拥挤厌恶(ATC)情形,另外还分析顾客均衡到达率的稳定性.因为得到的社会收益函数过于复杂,我们利用PSO算法得到服务台处于不同状态下顾客的社会最优到达率.最后,通过数值例子说明了系统性能指标的敏感性.     

基于排队系统的偏好差异性顾客服务策略分析

在服务商为不同偏好顾客提供差异性服务的排队系统中,其收益受到需求规模、顾客类型等因素影响,如何制定策略才能达到服务特定类型顾客并获取最大收益的目的？本文以服务时间与效果正相关的顾客密集型服务为背景,基于M/M/1模型对服务商为两种偏好顾客提供两种服务的情景进行研究,并将从偏好服务所获基准效用相对较低、较高的顾客分别定义为1类、2类顾客。结果表明,①随着潜在顾客规模的增加,最优策略所适用的3种基本策略依次为公平策略、优先服务2类顾客的策略以及仅服务2类顾客的排他性策略;②3种基本策略的适用范围仅与1类顾客的服务选择标准相关;③在优先服务某类顾客的策略中,有效到达速率及服务速度由另一类顾客的特征决定。     

具有不耐烦顾客和多重工作休假的排队库存系统

研究具有不耐烦顾客和多重工作休假的M/M/1/N排队库存系统模型,分别考虑了系统中库存为零时服务员休假和系统中顾客数为零时服务员休假两种休假方式,基于(s,S)库存策略,运用矩阵迭代方法得到了系统稳态概率分布,并给出系统相关性能指标,进而建立系统平均库存费用函数.通过数值算例对比分析了两种休假方式下的系统主要参数变化对系统重要性能指标的影响,并在最优费用的层面对两个模型的优劣进行了对比分析.     

具有Bernoulli休假的不可见M/M/1重试排队模型的进队策略分析

考虑具有常重试率和Bernoulli休假的M/M/1重试排队,到达系统的顾客仅知道服务台的状态.如果在顾客到达时刻服务台正忙,则顾客或以概率q加入到重试组中,或以概率1-q止步.在每次服务结束后,服务台或者以概率p开始一次休假,或者以概率1-p保持空闲状态.基于收入-支出结构,得到了个体最优进队策略,社会净收益最优进队策略和利润最优进队策略.对于这些最优进队概率的大小顺序我们给出了详细的证明.最后,给出了数值例子来阐述进队策略的影响.     

服务台不可靠的重试排队系统均衡分析

本文研究服务台不可靠的M/M/1常数率重试排队系统中顾客的均衡进队策略, 其中服务台在正常工作和空闲状态下以不同的速率发生故障。在该系统中, 服务台前没有等待空间, 如果到达的顾客发现服务台处于空闲状态, 该顾客可占用服务台开始服务。否则, 如果服务台处于忙碌状态, 顾客可以选择留下信息, 使得服务台在空闲时可以按顺序在重试空间中寻找之前留下信息的顾客进行服务。当服务台发生故障时, 正在被服务的顾客会发生丢失, 且系统拒绝新的顾客进入系统。根据系统提供给顾客的不同程度的信息, 研究队长可见和不可见两种信息情形下系统的稳态指标, 以及顾客基于收入-支出函数的均衡进队策略, 并建立单位时间内服务商的收益和社会福利函数。比较发现, 披露队长信息不一定能提高服务商收益和社会福利。     

不同价格水平下排队策略研究

在M/M/1排队中引入了不同的服务价格,基于"收益-成本"结构,以顾客和企业均追求利益最大化为出发点,在两种不可见情形下,研究了顾客均衡策略行为和企业最优服务定价决策,通过数值模拟,描述了休假期服务价格对顾客均衡策略的影响,以及几乎不可见情况下休假期服务价格对企业收益的作用和完全不可见情况下休假期服务价格随潜在到达率的变化情况,以及当企业获得最大收益时,正常工作期和休假期服务价格的关系.     

服务台不可靠的重试排队系统均衡分析

本文研究服务台不可靠的M/M/1常数率重试排队系统中顾客的均衡进队策略, 其中服务台在正常工作和空闲状态下以不同的速率发生故障。在该系统中, 服务台前没有等待空间, 如果到达的顾客发现服务台处于空闲状态, 该顾客可占用服务台开始服务。否则, 如果服务台处于忙碌状态, 顾客可以选择留下信息, 使得服务台在空闲时可以按顺序在重试空间中寻找之前留下信息的顾客进行服务。当服务台发生故障时, 正在被服务的顾客会发生丢失, 且系统拒绝新的顾客进入系统。根据系统提供给顾客的不同程度的信息, 研究队长可见和不可见两种信息情形下系统的稳态指标, 以及顾客基于收入-支出函数的均衡进队策略, 并建立单位时间内服务商的收益和社会福利函数。比较发现, 披露队长信息不一定能提高服务商收益和社会福利。     

带有N策略,启动时间和服务台故障的M/M/1排队的均衡策略

本文考虑带有N策略,启动时间和服务台故障的M/M/1排队的顾客的策略行为.当系统为空时服务台关闭,并且只有当系统中的顾客数达到一个给定的阈值时才会被激活,启动时间服从指数分布.服务台在工作时可能会故障,一旦发生故障,它立即被维修,维修的时间服从指数分布.我们得到了不同状态的均衡到达率并且给出了均衡社会收益函数.最后对均衡到达率和均衡社会收益进行了数值研究.     

带有负顾客和启动时间的排队系统最优策略分析

本文考虑带有负顾客和启动时间的排队系统的均衡策略和社会最优问题.负顾客到达时,会使得服务台故障,并且迫使正在接受服务的顾客离开系统.当系统中最后一名顾客的服务完成后,服务台立即关闭.当有新顾客到达时,服务台经历一段随机的启动时间,进而服务顾客.基于线性“收益-成本”结构,本文得到了顾客在几乎不可视和完全不可视两种情形下顾客的均衡进入概率.利用遗传算法得到顾客的最优进入概率.最后,通过数值例子展现了最优进入概率和最优社会福利关于系统参数的敏感性变化,并比较了两种信息水平下的最优社会福利.     

Customer equilibrium and optimal pricing in an M/G/1 queue with heterogeneous rewards and waiting cost rates

We consider an unobservable M/G/1 queue in which customers are allowed to join or balk upon arrival. The service provider charges the same admission fee to all joining customers. All joining customers receive a reward from completion of service and incur a waiting cost. The reward and waiting cost rate are random, however the customers know their own values upon arrival. We characterize the customer’s equilibrium strategy and the optimal prices associated with profit and social welfare maximization.     

Maximum entropy analysis to the N policy M/G/1 queueing system with a removable server

We study a single removable server in an M/G/1 queueing system operating under the N policy in steady-state. The server may be turned on at arrival epochs or off at departure epochs. Using the maximum entropy principle with several well-known constraints, we develop the approximate formulae for the probability distributions of the number of customers and the expected waiting time in the queue. We perform a comparative analysis between the approximate results with exact analytic results for three different service time distributions, exponential, 2-stage Erlang, and 2-stage hyper-exponential. The maximum entropy approximation approach is accurate enough for practical purposes. We demonstrate, through the maximum entropy principle results, that the N policy M/G/1 queueing system is sufficiently robust to the variations of service time distribution functions.     

带负顾客启动期N策略的Geom/Geom/1工作休假排队

将带RCH抵消策略的负顾客、启动期和N策略引入离散时间排队.休假策略为空竭服务多重工作休假.负顾客一对一抵消队首正在接受服务的正顾客,若系统中无正顾客时,到达的负顾客自动消失,负顾客不接受服务.利用拟生灭过程和矩阵几何解方法,给出了稳态队长分布及其随机分解.通过数值例子表现了启动率和负顾客到达率对稳态队长的影响.     

Optimal allocation of priority in a M/M/1 queue with two types of customers

We consider a M/M/1 queue with two types of customers.The server suffers some loss when a non-priority customer joins the queue if the size of the queue is greater than some predetermined level N. The problem is to decide which group receives priority in such a way as to minimize the expected cost per unit of time.We show first how to determine the optimal decision. Then we introduce approximations that enable us to show that the optimal decision has a simple behaviour as a function of N, the arrival and service parameters.     

Delay analysis of a two-class batch-service queue with class-dependent variable server capacity

In this paper, we analyse the delay of a random customer in a two-class batch-service queueing model with variable server capacity, where all customers are accommodated in a common single-server first-come-first-served queue. The server can only process customers that belong to the same class, so that the size of a batch is determined by the length of a sequence of same-class customers. This type of batch server can be found in telecommunications systems and production environments. We first determine the steady state partial probability generating function of the queue occupancy at customer arrival epochs. Using a spectral decomposition technique, we obtain the steady state probability generating function of the delay of a random customer. We also show that the distribution of the delay of a random customer corresponds to a phase-type distribution. Finally, some numerical examples are given that provide further insight in the impact of asymmetry and variance in the arrival process on the number of customers in the system and the delay of a random customer.     

The GI/M/1 queue with phase-type working vacations and vacation interruption

Consider a GI/M/1 queue with phase-type working vacations and vacation interruption where the vacation time follows a phase-type distribution. The server takes the original work at the lower rate during the vacation period. And, the server can come back to the normal working level at a service completion instant if there are customers at this instant, and not accomplish a complete vacation. From the PH renewal process theory, we obtain the transition probability matrix. Using the matrix-analytic method, we obtain the steady-state distributions for the queue length at arrival epochs, and waiting time of an arbitrary customer. Meanwhile, we obtain the stochastic decomposition structures of the queue length and waiting time. Two numerical examples are presented lastly.     

On a BMAP/G/1 G-queue with setup times and multiple vacations

In this paper, we consider a BMAP/G/1 G-queue with setup times and multiple vacations. Arrivals of positive customers and negative customers follow a batch Markovian arrival process (BMAP) and Markovian arrival process (MAP) respectively. The arrival of a negative customer removes all the customers in the system when the server is working. The server leaves for a vacation as soon as the system empties and is allowed to take repeated (multiple) vacations. By using the supplementary variables method and the censoring technique, we obtain the queue length distributions. We also obtain the mean of the busy period based on the renewal theory.     

Analysis of M/M/S queues with 1-limited service

In this paper, a multiple server queue, in which each server takes a vacation after serving one customer is studied. The arrival process is Poisson, service times are exponentially distributed and the duration of a vacation follows a phase distribution of order 2. Servers returning from vacation immediately take another vacation if no customers are waiting. A matrix geometric method is used to find the steady state joint probability of number of customers in the system and busy servers, and the mean and the second moment of number of customers and mean waiting time for this model. This queuing model can be used for the analysis of different kinds of communication networks, such as multi-slotted networks, multiple token rings, multiple server polling systems and mobile communication systems.