A comparative study of the inventory system with service facility and postponed demands

In this article, we present a continuous review （s,S） inventory system with a service facility consisting of finite buffer （capacity N ） and a single server. The customers arrive according to a Poisson process. The individual customer＇s unit demand is satisfied after a random time of service, which is assumed to be exponential. When the inventory level drops to s＇an order for Q（= S-s） items is placed. The lead time of reorder is assumed to be exponential distribution. An arriving customer, who finds the buffer is full, enters into the pool of infinite size or leaves the system according to a Bernolli trial. At the time of service completion, if the buffer size drops to a preassigned level L （1 〈 L 〈 N） or below and the inventory level is above s, we select the customers from the pool according to two different policy ： in first policy, with probability p （0 〈 p 〈 1） we select the customer from the head of the pool and we place the customer at the end of the buffer; in the second policy, with p （0 〈 p 〈 1） the customer from the pool is transferred to the buffer for immediate service and after completion of his service we provide service to the customer who is in the buffer with probability one. If at a service completion epoch the buffer turns out to be empty, there is at least one customer in the pool and the inventory level is positive, then the one ahead of all waiting in the pool gets transferred to the buffer, and his service starts immediately. The joint probability distribution of the number of customers in the pool, number of customers in the buffer and the inventory level is obtained in the steady-state case. Various stationary system performance measures are computed and total expected cost rate is calculated. A comparative result of two models is illustrate numerically.     

替代性需求下的分销系统库存决策

研究由两个制造商和多个地区总经销商组成的分销系统,假设每个地区总经销商都经销这两个制造商的产品,且在同一个地区总经销商处,两个制造商的产品需求具有一定替代性。在分别给出了地区总经销商和制造商的总利润模型的基础上,建立了以整个分销系统总利润最大为目标、以地区总经销商的服务水平为约束条件的分销系统利润优化模型,并通过仿真分析了定价参数、忠诚度参数和需求方差的变化对分销系统绩效的影响。     

考虑旧产品质量和企业服务水平的混合系统批量模型

对一类考虑旧产品质量和服务水平的混合系统进行研究.产品使用后从顾客处返回,但只有满足质量要求的部分旧产品用于再制造,其余的被处置.在一个模型周期里,可再制造品被存储起来,并在期末成批转入生产车间,在需要时用于再制造.需求确定且由制造新品和再制造品来满足,二者构成了服务性产品库存,可再制造品库存由生产车间和旧产品仓库的可再制造品组成.延迟交货是允许的,但缺货量受到企业服务水平的制约.对一次制造准备和至少一次再制造准备的策略与至少一次制造准备和一次再制造准备的策略分别进行研究,提出了准备次数为整数的最优制造批量、再制造批量等的求解方法.本文是对文[11]、文[12]、文[13]研究的进一步推广.     

双重供货模式下的装配系统协调机制设定与优化

建立了由两供应商、单制造商构成的基于双重供货模式的装配系统,其中：制造商需要向供应商1订购零部件,而 供应商2对制造商采用VMI模式供应零部件. 分析在供应商生产时间不确定的前提下,装配系统的订货时间决策与 协调问题. 研究结果表明,分散模式下的供应链总体成本和准时供货率均劣于集中模式. 当制造商对供应商采用传 统的激励机制时,尽管能够降低供应链成本,但并不能使得系统总成本达到集中模式下的系统最优成本. 采用改进 的激励机制时,可以实现分散模式下系统总成本的完全协调,但并不能保证实现Pareto改善. 在此基础上,进一步 找到能使系统达到整体绩效最大化的协调机制,并且可以实现系统成本的有效分配.     

下一代密集WLAN网络干扰管理机制

在密集高效无线局域网部署场景中,针对传统802.11协议造成用户公平性差和吞吐量低的问题,提出一种以用户为中心的资源配置方法。该方法通过对用户进行识别分类,以用户为中心配置信道和功率,在保证用户公平性的前提下,最大化网络吞吐量。提出的功率控制机制和用户识别方法可以很简单的应用于现有无线局域网系统中。仿真结果表明,提出的资源配置方法平均提升单位基本服务集吞吐量47.3%,干扰最严重的基本服务集的吞吐量提升190%,每个基本服务集的边缘用户的吞吐量平均提升约74.3%。     

供应中断情况下的库存控制模型研究

研究了按单装配系统中一个无时间界限的定期查看库存模型.针对该装配系统中,每个周期的总装配能力有限,产品由不同的组件装配而成,各组件的订货提前期确定,订货提前期的概率分布依赖于外生可观测的马尔可夫链的状态,组件的订货成本是线性的,未能满足的需求全部按照缺货处理,首先提出了一种在给定的状态依赖基础库存策略的情况下,确定长期平均成本的方法,该方法考虑了所有基础库存策略的状态;之后,应用该方法分析了组件中断可能对企业库存状况和长期平均成本带来的影响.研究表明,状态不变的基础库存策略是最优的,并且组件供应中断时间的长短比组件供应中断概率的大小对组件库存策略的影响更大.该研究结果对企业和管理部门中的中断管理以及应急事件计划的制定有一定的参考价值.     

HEALTHCARE： A COMPLEX SERVICE SYSTEM

Healthcare is indeed a complex service system, one requiring the technobiology approach of systems engineering to underpin its development as an integrated and adaptive system. In general, healthcare services are carried out with knowledge-intensive agents or components which work together as providers and consumers to create or co-produce value. Indeed, the engineering design of a healthcare system must recognize the fact that it is actually a complex integration of human-centered activities that is increasingly dependent on information technology and knowledge. Like any service system, healthcare can be considered to be a combination or recombination of three essential components — people (characterized by behaviors, values, knowledge, etc.), processes (characterized by collaboration, customization, etc.) and products (characterized by software, hardware, infrastructures, etc.). Thus, a healthcare system is an integrated and adaptive set of people, processes and products. It is, in essence, a system of systems which objectives are to enhance its efficiency (leading to greater interdependency) and effectiveness (leading to improved health). Integration occurs over the physical, temporal, organizational and functional dimensions, while adaptation occurs over the monitoring, feedback, cybernetic and learning dimensions. In sum, such service systems as healthcare are indeed complex, especially due to the uncertainties associated with the human-centered aspects of these systems. Moreover, the system complexities can only be dealt with methods that enhance system integration and adaptation.     

基于能力降阶的军事信息系统毁伤评估模型

针对信息系统毁伤评估中评估目标难以界定的问题,提出了基于能力降阶的毁伤评估模型,将支撑作战任务的信息能力降阶为子任务能力级、信息服务级和服务组件级。分析了毁伤在上下级之间的逻辑传递关系、线性传递关系、指数衰减关系和门限判别关系,并基于解释结构模型,构建毁伤影响关系矩阵,用以分析同级之间的毁伤级联传播关系,定义模型的毁伤评估树结构和评估计算步骤。最后,以防空反导指挥信息系统为算例,分析验证了模型的有效性。     

供应链复杂性对组织学习和运营竞争力的影响

供应链上的企业越来越认识到组织学习对其基本生存与持续发展的重要性,然而组织学习面临着内外复杂环境的影响.从供应链内部复杂性、上游复杂性和下游复杂性三个维度探讨了组织内部学习和外部学习,并探究了两种组织学习对企业运营竞争力的影响.基于全球10个国家的317家高绩效制造(high performance manufacturing,HPM)企业的一手数据,采用结构方程模型方法,提出并验证了"复杂性-组织学习-运营竞争力"的模型.结果表明,供应链上游复杂性对内部学习和外部学习均有负面影响,下游复杂性对内部学习有负面影响,而内部复杂性对内部学习和外部学习均无显著影响;内部学习显著提升了运营竞争力中的交付、创新、客户服务,而外部学习显著提升了质量和客户服务.     

一对多交互式在线客户服务排队模型

以聊天工具为基础的在线客服大量取代了电话形式的传统客服.与电话客服不同,一个在线客服人员能同时为多个顾客提供交互式的服务,而传统的排队公式都是以一对一服务为基础推导的,无法直接用来计算在线客服的排队指标.分析了一对多交互模式下的排队特点,提出了该模式下的服务水平指标,构建了包含顾客层和消息层的双层排队模型,推导了系统平...     

呼叫中心中排队系统服务率的动态控制方法

对多服务台、缓存容量受限、用户等待太久后厌烦而中途离开的呼叫中心排队系统,运用马尔科夫决策过程理论,建立折扣准则最小期望代价函数模型,动态控制服务率.结果表明,合适的服务台数和到达率的情况时,最优策略会具有单调性,提高决策的效率, 并且结合有限阶段和无限阶段进行分析,兼顾了系统稳态工作时服务台利用率.     

维持道路服务水平的模糊控制算法设计及其仿真

道路服务水平是标志运输服务质量的重要指标，随着城市道路网络中交通流量的迅速增加，维持期望的道路服务水平显得越来越重要，本文利用模糊控制原理设计了通过改变路段进口信号灯配时方案，控制进入路段的交通流量，实现维持道路服务水平的信号交叉口控制算法，对算法进行仿真分析表明，利用模糊控制原理设计的交叉口信号配时方案，能够很好地反映道路管理者的决策思想，也表明要维持道路期望的服务水平，交叉口的信号配时方案必须随着交通流量的改变而改变。     

PRICE AND SERVICE COMPETITION WITH MAINTENANCE SERVICE BUNDLING

In many equipment manufacturing industries,firms compete with each other not only on products price,but also on maintenance service.More and more traditional products oriented firms are offering their customers products bundled with maintenance service(P&S bundles).In this study,we examine firms’ incentive to offer customers products bundling with long-term maintenance or repair support service in a duopoly competitive environment.When providing P&S bundles,a firm need to determine the service level(in terms of average response time guarantee for the service in this paper) to offer and needs to build a service facility to handle the maintenance service requirements.Based on the analysis of three sub-game models,we characterize the market conditions in which only one firm,both firms or neither firm will offer P&S bundles.Finally,we analyze the affects of serval market factors on firms’ strategy choices.     

分布式库存系统策略探讨与仿真

如何解决供需不平衡,实现供应链中成本与服务水平的协调控制是研究的一个重要问题,分布式库存系统的实施关键在于决策持有多少库存以及需求到达时库存缺乏如何处理。以具有自主决策权的几个零售商为对象,研究其库存转移状况,以及成本与服务水平,通过建立库存调拨模型,提出了三种调拨策略,包括自私型调拨策略,合作型调拨策略,混合型调拨策略,并根据这三种策略运用Anylogic软件进行仿真,分析比较三种策略的有效性,以得到最优结果。

Abstract：

The key point of the study is how to solve the imbalance of supply and demand, and how to coordinate the cost and service level in the supply chain. To solve the key problems in implementing the multi-location inventory system which lie in deciding how many items to hold at each retailer and how to deal with if there is a demand for an item at a retailer that has none of them in stock. A few independent decision-making retailers are the main research objects. It was targeted to study the transfer of their inventory status, as well as the costs and service levels, and through the establishment of inventory transshipment model, three transshipment strategies, including self-based strategy, cooperation-based strategy, hybrid strategy, were suggested. Then the software of Anylogic was adopted to simulate, analyze and compare the effectiveness of the three strategies in order to obtain optimal results.     

基于结构计算数据挖掘的可视化系统研究

为辅助工程设计人员理解结构分析计算得到的结果。根据工程应用的现状，提出有限元反演法并开发了一个基于结构计算数据挖掘的可视化试验系统3DVS。该系统的基本组成模块包括数据输入接口、结构建模、变换控制、真实感结构可视化、结构内力场可视化、剖面应力显示等。本研究所开发的试验系统成功地将大量数据转化为设计人员易于理解的形式，解决了现有CAD软件中结构计算程序输出数据不能满足三维可视化表现要求的问题，实现了科学计算可视化技术在建筑工程设计领域的新的探索性应用，证实了本研究能够为工程结构仿真服务，具有重要的实用价值和广阔的应用前景。     

民航旅客忠诚度模型预测方法

结合现阶段民航企业的特点,重点研究如何利用忠诚度预测模型提高企业的服务水平方法,在此基础上,建立提高旅客忠诚度的决策服务体系.通过建立符合民航的旅客忠诚度模型,运用PLS-SEM方法量化忠诚度指标;由于调查数据量的限制,研究在小样本集下的偏最小二乘法预测方法,制定提高忠诚度指标策略.对实际采集数据的分析试验也验证了该方法有助于细化分析航空公司服务水平,操作性强,效率高,可为民航企业改进服务提供决策支持.     

一种分散式空间服务网络模型

提出分散式空间服务网络模型来克服空间服务宿主服务器间的"孤岛"状态以及网络的伸缩性障碍。以Super Geo-Peer、Basic Geo-Peer和Inferior Geo-Peer分别建模不同能力的空间服务宿主服务器和空间服务消费者。在分散式空间服务网络模型的服务发现过程中,建立关于Super Geo-Peer和Basic Geo-Peer间比率的系统代价模型,并推导出满足最小系统代价的最佳比率。在此基础上,给出了一种维护分散式空间服务网络系统的可选方案。     

基于组件的标准化显控台模拟器开发框架

针对标准化显控台模拟器的研制,分析了模拟器研制中的共性,提出解决方案,设计了标准化显控台模拟器开发框架.框架的核心是组件管理模块,它管理元件组件、服务组件和模型组件,负责消息响应和内部通讯并控制组件行为.为使开发更加便利和标准化,开发框架还包括标准信息元数据库及管理系统、基础功能类库、标准化对象模型开发工具以及标准组件框架生成向导.另外,辅助以图形方式描述了开发框架各部分的基本结构关系、组件接口以及组件管理工作流程.     

分销系统中多委托人及委托人可能合作的委托代理问题

分析了具有两个制造商和一个零售商组成的分销系统中的委托代理问题。在该系统中,两制造商作为委托人,零售商作为代理人。在假设两制造商的产品对于服务水平敏感且产品间存在部分替代性的基础上,制造商通过对零售商实施奖金激励来实现其利益最大化的目的。分别考虑制造商非合作竞争和合作行为这两种情况,建立了相应的委托代理模型。仿真结果表明,制造商在非合作竞争中受损,而零售商得到了"渔翁之利";特别是在制造商的商品间替代性逐渐增强时,这种受损更为严重,而零售商得利更多。同时,仿真结果表明,合作对制造商有利,而对零售商不利。     

Complexity of system maintainability analysis based on the interpretive structural modeling methodology: Transdisciplinary approach

This paper outlines a diagnostic approach to quantify the maintainability of a Commercial off-the-Shelf (COTS)-based system by analyzing the complexity of the deployment of the system components. Interpretive Structural Modeling (ISM) is used to demonstrate how ISM supports in identifying and understanding interdependencies among COTS components and how they affect the complexity of the maintenance of the COTS Based System (CBS). Through ISM analysis we have determined which components in the CBS contribute most significantly to the complexity of the system. With the ISM, architects, system integrators, and system maintainers can isolate the COTS products that cause the most complexity, and therefore cause the most effort to maintain, and take precautions to only change those products when necessary or during major maintenance efforts. The analysis also clearly shows the components that can be easily replaced or upgraded with very little impact on the rest of the system.