实时交通信息作用下公交多公司博弈研究

研究了提供公交车实时到站信息服务,对乘客出行行为的影响以及公交公司在基于自身利润最大化目标下,决策是否提供信息进行分析.模型中假设,理性的出行者随机到达车站或者利用公交信息提前规划自己的行程.计划出行的人数依赖于公交车的发车频率以及提供信息的质量的高低.基于固定需求的乘客出行分析,研究了公交公司在选择是否提供信息和设定运营频率以最大化利润.得到不同运营策略的公交公司的发车频率及最优利润.发现乘客利用信息成本越低,公交公司在提供信息方面越积极,公交公司可能在降低社会总成本的情况下落入“囚徒困境”.如果乘客利用信息的成本较高,而信息提供成本较低,则可能出现一家公交公司提供信息而另一家通过增加服务频率来差异竞争的均衡结果.     

需求替代的两产品动态批量最优预测时阈研究

研究了存在需求单向替代的两产品动态批量决策的最优预测时阈问题.构建了包含替代成本、生产转换成本和库存成本在内的成本最小化模型,分析得出在只存在3类再生点(Ⅰ类、Ⅱ类和Ⅲ类)情形下的再生点单调性特征.同时,设计出了多项式时间的前向动态规划算法.运用数值试验分析了最优预测时阈与生产转换成本、替代成本、需求特征(需求增长性和...     

风险厌恶零售商考虑信息预测成本的协调机制

在CVaR风险度量准则下,将信息预测成本作为运营成本之一,建立了风险厌恶的零售商的需求信息预测投入和订货量的联合决策随机模型,研究了风险态度对零售商最优决策的影响.通过分析得出在分散决策下,随着零售商风险厌恶程度的增加,零售商提高信息预测水平,以减小需求不确定风险.同时减少订货量,降低订货过量的风险.证明了在一定条件下,传统的收益共享契约能实现供应链协同,但适用范围较小.由信息预测成本分担与收益共享组成的联合契约可扩大供应链协同的范围,消除风险态度和双重边际对零售商决策行为的影响,使得零售商的需求预测水平和订货量同时达到系统风险中立环境下的最优水平.     

附加惩罚成本的最优转移支付设计——批发价格合约的一种制度改进

非激励性和非协调性是批发价格合约的主要制度缺陷,其原因在于分散决策模式下,供应商、零售商的个体理性行为所导致的集体非理性.本文提出了解决此类问题的一种制度改进方案,并考察了单期经营和无限期经营两种情形下该种制度设计的实际效果.实证检验表明,附加惩罚成本的最优转移支付安排能够促进供应商、零售商的协调行为,博弈的唯一纳什均衡解即是供应链的理论最优状态.在该状态下,供应商、零售商及供应链整体的利润都较实际状态下的利润水平增长了19.75％.     

风险质检行为下的模糊生产-库存决策

本文研究在风险质检行为下需求与生产率具有模糊属性的由一个制造商与一个零售商构成的生产-库存问题。在假设制造商生产的产品存在质量缺陷,零售商在质检过程中存在质检风险的基础上,分别建立了需求模糊下的生产-库存总成本模型,需求与生产率模糊下的总成本模型,运用符号距离法进行了逆模糊化处理,将模糊化的生产-库存总成本转化为确定性成本。证明了两类情形下的总成本均是关于最优订购量与最优缺货量的联合凸函数。数值分析结果表明：随着期望缺陷率的增加,最优订购量增加,最优缺货量减少,最优成本增加,且最优成本增加的速度越来越快。一类质检风险增大引起总成本增加,二类质检风险增大引起总成本减少。最优订购策略对质检一类风险敏感,对质检二类风险不敏感。     

无外部市场条件下中间产品转移价格的研究

系统地讨论了不存在外部市场条件下中间产品最优转移价格的确定方法. 首先在各分厂 成本函数和最终产品需求函数已知条件下, 分别讨论了各分厂产量相同和产量不同情形下中 间产品最优转移价格的确定问题. 接着讨论了各分厂成本函数和最终产品需求函数未知条件 下中间产品转移价格的确定问题. 本文提出的三种确定中间产品转移价格的方法均给出了具 体的计算公式, 具有较大的理论价值和应用价值.     

基于交货期库存协调的供应链转移定价研究

在将缺货成本和延期惩罚成本纳入决策模型的前提下,对供应商—制造商两阶供应链在转移定价、安全库存,以及总成本之间的相互作用进行了探讨:首先探讨基于 Stackelberg 收益共享定价机制的最优决策;然后,以一体化供应链为参照系,探讨对供应链各成员的行为进行优化的两部制(two-part scheme)收益共享转移定价决策在实践中的运用;最后,探讨模型中部分变量变化对最优决策所产生的影响.通过分析发现,承诺的交货期、延期惩罚成本与缺货成本将会影响供应链的总成本和转移定价决策,进而影响供应商的最优库存决策,而制造商则可以通过适当的激励机制设计,激励供应商按照供应链整体最优的方式进行转移定价、安全库存及相关决策.     

考虑努力因素的供应链收益共享演化契约

在需求随机、努力水平影响需求的供应链环境里,在传统供应链收益共享契约基础上构建了一种演化契约.并在委托代理框架下,对该演化契约进行了研究.首先分析了销售商的努力因素对收益共享契约的影响,得出了销售商努力水平反应函数及最优投入值;其次,研究得出了供应商在收益共享契约中,向销售商所提供的最优收益共享比例,以及最优的分担销售商的努力成本比例;再次,论证了本文所研究的收益共享演化契约可以实现供应链协调;最后,通过算例分析验证本文研究结论的有效性.     

可控提前期下基于交易信用契约的供应链协调模型

提前期压缩是企业在激烈竞争环境中赢得与保持竞争优势的一种有效方式。本文制定了一个交易信用(即零售商向供应商提前付款)契约,讨论了可控提前期下非一体化供应链中的库存协作问题,得到了供应商与零售商的最优策略组合。研究表明,当提前期压缩成本系数足够小时,供应商采用所设计的交易信用契约,能够在满足零售商个体理性约束的前提下,赚取可观的成本节约金额,而且比纯粹延期付款协调零售商订货行为时所获得的成本节约更多;并且通过对该成本节约的合理分配,实现了供应商与零售商成本境况的帕累托改进乃至整条供应链的协调。最后的数值分析考察了安全库存系数、提前期需求波动、或者供应商的资金投资收益率对供应链最优策略与成本节约幅度的影响。     

基于可控提前期的两供应商-单制造商协同模型

本文建立了一个基于BOM表关系的两供应商-单制造商供应链模型,在需求服从正态分布和给定服务水平约束条件下,决策制造商分别向两供应商的订货提前期和订货批量,使得供应链成本最优.文章通过模型分析得出所建立的模型是一个凸规划问题,存在唯一的最优解,并且给出了模型的求解算法,最后通过一个算例说明了模型和算法的有效性.     

Mixed-fleet single-terminal bus scheduling problem: Modelling,solution scheme and potential applications

Reducing pollutant emissions and promoting sustainable mobility solutions, including Public Transport (PT), are increasingly becoming key objectives for policymakers worldwide. In this work we develop an optimal vehicle scheduling approach for next generation PT systems, considering the instance of mixed electric / hybrid fleet. Our objective is that of investigating to what extent electrification, coupled with optimal fleet management, can yield operational cost savings for PT operators. We propose a Mixed Integer Linear Program (MILP) to address the problem of optimal scheduling of a mixed fleet of electric and hybrid / non-electric buses, coupled with an ad-hoc decomposition scheme aimed at enhancing the scalability of the proposed MILP. Two case studies arising from the PT network of the city of Luxembourg are employed in order to validate the model; sensitivity analysis to fleet design parameters is performed, specifically in terms of fleet size and fleet composition. Conclusions point to the fact that careful modelling and handling of mixed-fleet conditions are necessary to achieve operational savings, and that marginal savings gradually reduce as more conventional buses are replaced by their electric counterparts. We believe the methodology proposed may be a key part of advanced decision support systems for policymakers and operators that are dealing with the on-going transition from conventional bus fleets towards greener transport solutions.     

基于“搭便车”行为的双渠道供应链库存竞争和促销策略

本文建立了由一个制造商和一个零售商组成的双渠道供应链模型，研究了随机需求下"搭便车"行为和渠道间缺货替代行为对供应链库存竞争与促销决策的影响。结果表明：分散式决策下，网络渠道替代率越高，零售商的最优订购量越大，同样的零售渠道替代率越高，制造商会为网络渠道提供更多的库存；而"搭便车"行为对零售商与制造商订购量的影响则取决于渠道替代率的变化，但"搭便车"行为会降低零售商促销努力水平。数值分析发现：分散式决策下，零售商最优订购量随"搭便车"行为的增加而减少。然而制造商的最优库存量并非随着"搭便车"行为程度的增加而增加，不同的是制造商网络渠道最优库存量取决于市场需求对传统零售渠道促销努力水平的弹性系数，即制造商网络渠道最优库存量随"搭便车"行为的增加先增加后减少。通过比较发现在不同的"搭便车"行为程度、传统零售渠道替代率、网络渠道替代率下，集中式决策下供应链期望收益大于分散式决策下供应链期望总收益。     

Investigating the effect of product variants,and demand distributions on the optimal demand supply network setup

In today's marketplace, consumers are looking for product variety and low prices. In this paper, we investigate how product variation and demand distributions affect demand supply network optimality in a real-life based setting. The research methodology was based on a novel Petri net formulation, which employs reachability analysis to demand supply network optimisation. We found that in our case study localised final assembly is justified with one or two product variants, but a centralised production should be favoured with three or more product variants. We also noted the sensitivity of this result to transport cost/inventory carrying cost tradeoff.     

Stress and the bus driver in the UK transport industry

This study was carried out to identify potential sources of stress for bus drivers working for the established operator in a major UK city, six months after the deregulation of bus transport. The focus was to assess the mental health and job satisfaction of the drivers. An interview programme was followed by a questionnaire survey of 376 male bus drivers. Major problem areas related to health and home-related concerns, problems intrinsic to the job, lack of involvement and support during the organizational changes occurring and fears regarding physical assault. Existing problems had been intensified as a result of streamlining and increased competition. The bus drivers were found to demonstrate lower levels of job satisfaction and unfavourable scores on mental-health indices when compared to normative samples, which was associated with their work-related stressors. The impact was significantly reduced for those men driving the newer minibuses in contrast to the traditional 72-seater double-decker buses.     

针对存在传染效应突发事件的资源布局问题研究

本文针对一类具有传染效应的突发事件建立资源布局模型。具有传染效应的突发事件是指在某地区发生事件,在其周围一定距离内的其他地区也会发生同类事件。对初始发生事件供应不同的资源将影响到其他地区的资源需求,因此整个地区的资源需求表现为多个需求组合。本文建立的模型考虑到某个地点发生事件带来的多种资源需求组合,将问题分为两个阶段进行分析,并同时考虑选址和资源配置来满足该地区发生事件需求以及引发的其他地区的资源需求。针对此模型,构造两层的禁忌搜索算法,并在最后给出算例。     

Inter-city bus scheduling under variable market share and uncertain market demands

Bus scheduling is essential to a carrier's profitability, its level of service and its competitiveness in the market. In past research most inter-city bus scheduling models have used only the projected (or average) market share and market demand, meaning that the variations in daily passenger demand that occur in actual operations are neglected. In this research, however, we do not utilize a fixed market share and market demand. Instead, passenger choice behaviors and uncertain market demands are considered. Stochastic and robust optimizations and a passenger choice model are used to develop the models. These models are formulated as a nonlinear integer program that is characterized as NP-hard. We also develop a solution algorithm to efficiently solve the models. They are tested using data from a major Taiwan inter-city bus operation. The results show the good performance of the models and the solution algorithm.     

Absence behaviour, turnover and disability: A study among city bus drivers in the Netherlands

Absenteeism, turnover and disability, and relationships between them have been studied among city bus drivers in the Netherlands. The theoretical framework for the study was a cumulative process model of work and health. Absenteeism among these drivers was two to three times as high as the national average, while the risk of disablement was more than twice as high as the risk for male Dutch civil servants in general. Bus drivers who had to leave their job for medical reasons did so at a younger age than other groups of civil servants. The main conditions leading to disablement related to the back, tendons and joints (35%), mental disorders (35%) and cardiovascular diseases (12%). It was shown that long-term absenteeism is a strong precursor of future disability. The research suggests a work-related process of progressive deterioration of health and well-being over a reasonably long period of time. Driving city buses seems to be an occupation with high risks for health and well-being.     

Absence behaviour,turnover and disability: A study among city bus drivers in the Netherlands

Abstract

Absenteeism, turnover and disability, and relationships between them have been studied among city bus drivers in the Netherlands. The theoretical framework for the study was a cumulative process model of work and health. Absenteeism among these drivers was two to three times as high as the national average, while the risk of disablement was more than twice as high as the risk for male Dutch civil servants in general. Bus drivers who had to leave their job for medical reasons did so at a younger age than other groups of civil servants. The main conditions leading to disablement related to the back, tendons and joints (35%), mental disorders (35%) and cardiovascular diseases (12%). It was shown that long-term absenteeism is a strong precursor of future disability. The research suggests a work-related process of progressive deterioration of health and well-being over a reasonably long period of time. Driving city buses seems to be an occupation with high risks for health and well-being.     

Portfolio-based airline fleet planning under stochastic demand

Airlines operate their fleet of aircraft over a relatively long time horizon during which the realized stochastic demand has the potential to profoundly impact the airlines’ financial performance. This makes the investment in a fleet of aircraft a highly capital-intensive long-term commitment, associated with inherent risks. We propose an innovative three-step airline fleet planning methodology with the primary objective of identifying fleets that are robust to stochastic demand realizations. The methodology presents two main innovation aspects. The first one is the use of the mean reverting Ornstein–Uhlenbeck process to model the long-term travel demand, which is then combined with discrete-time Markov chain transitions to generate demand scenarios. The second innovative aspect is the adoption of a portfolio-based fleet planning perspective that allows for an explicit comparison of different fleets, in size and composition. Ultimately, the methodology yields for each fleet in the portfolio a distribution of net present values of operating profit across the planning horizon and a list of key financial and operational metrics per year. The robustest fleet can be selected based on the operating profit generating capability across different realizations of stochastic demand. An illustrative case study is presented as a proof of concept. The case study is used to demonstrate the type of results obtained and to discuss the usefulness of the methodology proposed.     

基于需求更新的民航收入管理动态存量控制模型

本文对民航收入管理存量控制研究中具有里程碑意义的EMSR(Expected Marginal Seat Revenue)模型进行了评述,分析其存在的缺陷,提出将销售过程中获取的最新销售信息与需求的历史先验分布相结合,运用二维正态分布下的贝叶斯模型对需求分布进行更新,并将综合考虑新的需求预测、No-Show和取消订票等因素得到的新的需求限制与座位总数C相比较,给出更为通用的、市场反应更为灵敏的民航收入管理动态存量控制模型。