Performance Analyses of Production Inventory Systems Considering Service Time and Product Returns of Online Shopping

This paper considers a production inventory system with service time and product returns,dependent on the characteristics of online shopping behaviors. The customers arrive according to a Poisson process, in which the arriving customer requires an item in the inventory, as well as a server service that the service time is exponentially distributed. Moreover, there is one production facility to produce items according to(s, S) policy, and the production time also follows an exponential distribution. In the beginning, the stationary joint distribution is obtained in the product form for the queue length and the on-hand inventory level. Additionally, the resulting distribution is applied to derive some performance measures, which can be adopted to numerically calculate the optimal(s, S)policy. Finally, numerical analyses are processed to investigate the effects of some system parameters on the performance measures. The numerical results clearly indicate that the product return rate has a significantly monotonic effect on the optimal policy and optimal cost.     

A perishable inventory system with service facilities, <Emphasis Type="Italic">MAP</Emphasis> arrivals and <Emphasis Type="Italic">PH</Emphasis> — Service times

We consider a continuous review perishable （s,S） inventory system with a service facility consisting of a waiting hall of finite capacity and a single server. We assume two types of customers, ordinary and negative, arrive according to a Markovian Arrival Process （MAP）. An ordinary customer joins the queue and a negative customer instead of joining the queue removes one ordinary customer from the queue. The removal rule adopted in this paper is RCE （removal of a customer from the end）. The individual customer＇s unit demand is satisfied after a random time of service which is assumed to have a phase-type distribution. The life time of each item and the lead time of the reorders have been assumed to be independent exponential distributions. The joint probability distribution of the number of customers in the system and the inventory level is obtained for the steady state case. Various stationary system performance measures are computed and the total expected cost rate is calculated. The results are illustrated numerically.     

The M/PH/1 queue with working vacations and vacation interruption

We study an M/PH/1 queue with phase type working vacation and vacation interruption where the vacation time follows a phase type distribution. The server serves the customers at a lower rate in a vacation period. The server comes back to the regular busy period at a service completion without completing the vacation. Such policy is called vacation interruption. In terms of quasi birth and death process and matrix-geometric solution method, we obtain the stationary queue length distribution. Moreover we obtain the conditional stochastic decomposition structures of queue length and waiting time when the service time distribution in the regular busy period is exponential.     

An M/M/1 Queueing-Inventory System with Geometric Batch Demands and Lost Sales

This paper studies an M/M/1 queueing-inventory system with batch demands. Customers arrive in the system according to a compound Poisson process, where the size of the batch demands for each arrival is a random variable that follows a geometric distribution. The inventory is replenished according to the standard (s,S) policy. The replenishment time follows an exponential distribution. Two models are considered. In the first model, if the on-hand inventory is less than the size of the batch demands of an arrived customer, the customer takes away all the items in the inventory, and a part of the customer’s batch demands is lost. In the second model, if the on-hand inventory is less than the size of the batch demands of an arrived customer, the customer leaves without taking any item from the inventory, and all of the customer’s batch demands are lost. For these two models, the authors derive the stationary conditions of the system. Then, the authors derive the stationary distributions of the product-form of the joint queue length and the on-hand inventory process. Besides this, the authors obtain some important performance measures and the average cost functions by using these stationary distributions. The results are illustrated by numerical examples.     

具有强占优先权的不耐烦顾客的M/M/m/k排队模型

首先研究只有一类不耐烦顾客的M/M/m排队模型,其中顾客到达服从相互独立的泊松分布,服务时间服从相互独立的指数分布,到达率与服务率随着系统中的顾客数而发生变化。顾客的耐心等待时间(截止到服务开始前)服从指数分布。在此基础上进一步研究两类顾客到达的M/M/m/k排队系统。其中第一类顾客对于第二类顾客有强占优先权,两类顾客的到达率与服务率随着系统中顾客人数而发生变化。采用矩阵分析的方法得到了两类顾客各自的稳态分布,并有相应的性能分析,为系统的优化设计提供了依据。     

A batch arrival retrial queue with starting failures,feedback and admission control

This paper is concerned with the analysis of a feedback M^[X]/G/1 retrial queue with starting failures and general retrial times. In a batch, each individual customer is subject to a control admission policy upon arrival. If the server is idle, one of the customers admitted to the system may start its service and the rest joins the retrial group, whereas all the admitted customers go to the retrial group when the server is unavailable upon arrival. An arriving customer (primary or retrial) must turn-on the server, which takes negligible time. If the server is started successfully (with a certain probability), the customer gets service immediately. Otherwise, the repair for the server commences immediately and the customer must leave for the orbit and make a retrial at a later time. It is assumed that the customers who find the server unavailable are queued in the orbit in accordance with an FCFS discipline and only the customer at the head of the queue is allowed for access to the server. The Markov chain underlying the considered queueing system is studied and the necessary and sufficient condition for the system to be stable is presented. Explicit formulae for the stationary distribution and some performance measures of the system in steady-state are obtained. Finally, some numerical examples are presented to illustrate the influence of the parameters on several performance characteristics.     

顾客选择行为与库存

库存成本与顾客服务水平之间的权衡是供应链库存管理中的一个主要内容，从顾客服务水平的内涵出发，通过在两级树型库存系统引入顾客价值函数，构建出新的权衡顾客服务水平与库存成本的模型，并模拟分析了顾客选择行为对库存成本的影响。     

水平穿越法在带有不耐烦顾客的呼叫中心中的建模及应用

研究了一种需求服从泊松分布的多座席呼叫中心服务系统的两个问题, 其中考虑了顾客的不耐烦行为. 第一个问题中只有单一排队队列, 顾客进入系统后由于不能立即接受服务或等待时间超过其期望等待时间会选择放弃排队. 第二个问题中有两个排队队列, 主排队队列是顾客呼入队列, 次排队队列是座席提供回拨服务的队列, 且这个队列的顾客来源于由于等待时间超过其期望等待时间放弃排队的主排队队列的顾客. 本文利用水平穿越法得到了稳态时第一个问题的顾客平均等待时间及顾客总的放弃概率及第二个问题中座席繁忙的概率. 该方法不仅具有直观清晰的物理意义, 而且能避免排队系统中冗长的推导过程, 有利于快速简单解决问题. 数值分析表明第一个问题中顾客平均等待时间是座席数的凸函数, 并且顾客的不耐烦程度越高则他们的平均等待时间越短. 同时坐席数的增加在初期能够显著提高接通率, 达到一定数量后效用开始递减. 而且在系统其它参数确定且系统需求流较大情况下, 顾客的放弃率大小对顾客总的放弃概率大小的影响几乎可以忽略.     

Service Mechanism and Pricing Based on Fairness Preference of Customers in Queuing System

Service providers often adopt the mechanism of customer classification due to the heterogeneity of customer waiting cost. However, the classification service may cause unfairness feeling of regular customers, then affect the revenue and social welfare. This paper provides the first exact analysis about the situation that service providers offer two classes of non-preemptive priority service when customer fairness perception is explicitly modeled. We model customer fairness perception as a negative utility on regular customers that's proportional to the waiting time difference between the two queues. By analyzing a stylized M/M/1 queue in monopoly service system, we can derive important results some of which reaffirm existed research results. First, from the perspective of revenue maximization, service providers should adopt the mechanism of customer classification and set up the two kinds of customers where they can see each other. Next, considering customer utility maximization,service providers should cancel the mechanism of customer classification, and keep one queue(regular customers) only. Then, from the perspective of social welfare maximization, service providers shouldalso adopt the mechanism of customer classification but set up the two kinds of customers where they cannot feel each other. Finally, this paper concludes the optimal pricing based on customer classification in the above three different perspectives. This research shows important reference value and practical significance for service providers who adopt the mechanism of classification service.     

存在顾客购买转移的双分销渠道订货与库存转运策略

库存在渠道间的转运可以降低企业的缺货成本并提高对顾客的服务水平；当存在顾客购买转移时，双分销渠道的库存转运与渠道间的顾客竞争紧密相关，决策的复杂度增加. 该文针对实行转运的情形，研究了存在顾客购买转移的网上商城与传统零售商的最优库存策略，以及均衡解存在的条件，并与不实行转运的情形进行对比分析. 最后通过算例，指出存在顾客购买转移时，实行转运策略的优势.     

SERVICE LEVEL EVALUATION OF AN ASSEMBLY-TO-ORDER SYSTEM

An assembly-to-order system, which at the end the buffer distinguishes its assembly stages of the system from the downstream systems, is considered in this paper. The system produces semi-finished products for the downstream system and starts from a basic subassembly, and at each stage a component is assembled into the corresponding subassembly. The basic subassembly, components and buffer all follow a periodic-review, order up-to-level inventory policy. The buffer holds the semi-finished products to serve the specific demand from the downstream system. The service level of the system is determined by aggregate effects of the components held at stockpiles before the buffer and the basic subassembly. In order to measure the service level of the system, some notations and assumptions are made, on which the closed form expression of the service level of the system is achieved.     

Analysis of batch arrival queue with randomized vacation policy and an un-reliable server

This paper examines an M^[x]G/1 queueing system with an unreliable server and a delayed repair,in which the server operates a randomized vacation policy with multiple vacations.Whenever the system is empty,the server immediately takes a vacation.If there is at least one customer found waiting in the queue upon returning from a vacation,the server will be immediately activated for service.Otherwise,if no customers are waiting for service at the end of a vacation,the server either remains idle with probability p or leaves for another vacation with probability 1-p.Whenever one or more customers arrive when the server is idle,the server immediately starts providing service for the arrivals.The server may also meet an unpredictable breakdown and the repair may be delayed.For such a system the authors derive the distributions of some important system characteristics,such as the system size distribution at a random epoch and at a departure epoch,the system size distribution at the busy period initiation epoch,and the distribution of the idle period and the busy period.The authors perform a numerical analysis for changes in the system characteristics,along with changes in specific values of the system parameters.A cost effectiveness maximization model is constructed to explain the benefits of such a queueing system.     

面向重要供应商和客户的供应链设计方法

与重要供应商和高价值客户建立良好的关系，已经成为企业获得竞争优势的必然选择。本文从供应链核心企业的角度出发，提出了一种面向重要供应商和客户的供应链设计方法。该方法将供应链设计分成两个阶段。首先，利用模糊综合评判法对核心企业的供应商和客户进行评价，获得它们的重要度。然后，建立一个多目标混合整数规划模型来描述供应链设计问题。与基于成本最小化或利润最大化的传统供应链设计模型相比，该模型体现了关系管理的思想，考虑（1）优先向具有较高重要度的供应商采购原料，以建立长期稳定的合作关系。（2）分销中心的选址要尽量接近重要的客户或客户区，以缩短订货的提前期，提高客户服务水平。     

批量需求模式下的随机库存管理策略

考虑一类具有(s,s+q)订货策略的批量需求随机库存系统。需求的到达形成复合Poisson过程,当库存水平下降到s时管理员立即补货至最大仓储量s+q.通过构建库存和缺货状态下的状态转移方程,研究了库存和缺货的稳态概率分布;进一步建立库存成本函数和设计了一种有效的算法,研究库存系统的最优控制策略并考察参数的敏感性。     

维修器材联合订货的库存决策模型

分析了一种多品种维修器材联合订货的库存决策模型,该模型采用连续检查的多品种统一订购库存策略。维修器材库存控制的目的是在确保维修器材服务水平的基础上,降低库存成本。根据这一思想设计算法,首先假设订货点和订购提前期为零,根据库存成本确定最大库存量,然后考虑订货点和订购提前期不为零的情况,根据维修器材满足率确定各品种维修器材的订货点,从而求得决策参数。最后通过实例证明模型和算法的有效性。     

客户低估服务价值情境下混合产品定价策略

针对服务价值初始被客户低估的现象,若制造企业将产品服务集成并捆绑销售,将产生客户不愿为混合产品支付的问题,考虑客户对衍生服务价值感知的波动性,将客户购买混合产品的过程视为一个包含实物期权的多阶段动态投资规划,并通过贝叶斯统计估算客户服务价值感知的波动率,实现对混合产品的多阶段分割式定价,以好孩子旗下口袋车POKIT 2为例,验证了定价策略的可行性与有效性。研究表明:基于客户理解价值的定价策略使得供需交易更有灵活性;客户低估服务价值的持续时间决定了客户购买的价值理解;客户低估服务价值时,混合产品的总价大于客户未低估服务价值时混合产品的价格。     

网络消费者行为影响因素分析及实证研究

保持网络顾客忠诚是电子商务企业提高利润率和实现可持续发展的重要前提,其关键是明晰网络顾客忠诚的影响因素和影响途径.本文以计划行为理论为依据,分析了电子商务环境下消费者行为意向和实际消费行为的各种影响因素,建立了整合电子商务服务质量、顾客满意、情感关系和切换障碍的网络顾客忠诚影响模型.在此基础上提出了相应的假设,并通过实证方法对假设模型进行验证.研究发现,顾客忠诚行为意向是实际消费行为最直接的影响因素,而顾客满意、情感关系以顾客行为意向为中介间接影响顾客实际消费行为;网站使用经历、服务可靠性、安全与隐私、客户服务经历等因素通过顾客满意间接影响顾客忠诚行为意向.     

基于非线性边际支付意愿的信息产品定价策略研究

提出了非线性边际支付意愿假设，有效地克服了线性假设的缺陷；通过对消费者行为的分析，证明了每位消费者都存在理想消费量，且理想消费量是偏好参数的严格递增函数；通过对厂商行为的分析，证明了厂商的版本质量及其对应的价格都是偏好参数的非减函数；基于消费者和厂商行为的动态博弈分析，建立了信息产品定价策略的一般变分模型，并给出模型求解方法和计算结果. 模型结果表明，厂商的最优定价策略是：对于高端用户，厂商采取的是最大质量的固定定价策略；对于低端用户，厂商采取按质定价策略. 该结果对信息产品定价具有一定的指导意义.     

最小化运输与库存费用的两级分销策略分析

研究的两级分销库存系统由一个分销中心和N个零售商组成,设两级库存补充均采取周期订货策略,在每个零售商处的客户需求是随机的且服从一定的概率分布.我们的目标是在满足给定的客户服务水平的条件下,寻求该供应链运输和两级库存总费用的最小化.通过对运输及两级库存费用之间的关系分析,我们给出了一启发式算法,确定出了零售商的补货时刻、补货数量与车辆的行车线路.     

设备多状态、多类顾客制造系统的生产速率和库存分配联合决策

在生产制造系统中, 设备状态严重制约系统产能, 并增加生产过程的不确定性. 为应对不确定性对系统的影响, 对顾客进行细分, 实施差异化服务. 在顾客泊松达到、 缺货不补的假设下, 研究了设备多状态、多类顾客制造系统的生产和库存分配联合决策问题. 利用马尔科夫决策理论, 建立了系统在无限期期望折扣总成本准则和平均成本准则下的最优方程, 并证明了最优策略具有相似的结构性质. 最优生产速率策略是生产阈值水平随设备状态非增的阈值策略, 即当库存水平降至该阈值水平之下时, 以允许的最大生产速率生产, 否则不生产. 最优库存分配策略是分配阈值水平随设备状态非增的阈值策略. 另外, 缺货成本大的顾客具有较低的分配阈值.