基于网络外部性的市场结构动态演化分析

网络外部性是网络产业最显著的特征,其强度的大小影响着企业的各种竞争战略(如差异化战略、定价战略、兼容性战略等),从而导致了不同的市场结构.以市场动态发展的观点,通过构建动态古诺模型,讨论网络外部性作为进入壁垒影响企业的市场进入决策以及市场结构动态调整的问题.通过对网络外部性强度作为主要参数的均衡点的稳定性分析,确定网络外部性强度是决定企业能够进入市场和获得市场竞争优势的关键因素,并对市场的动态调整过程起着决定性推动作用.因此,企业如何认识网络产业的特征从而发挥网络效应的市场壁垒作用,行业管制者如何协调企业的市场进入都将对企业竞争战略的制定及行业管制具有重要的现实意义.     

网络外部性对寡头企业产品创新影响研究

以古诺模型和斯塔克尔伯格模型为基础模型,比较研究网络外部性对寡头垄断企业产品创新决策的影响。研究发现,网络外部性变化会对古诺博弈参与者与斯塔克尔伯格博弈参与者的创新决策造成不同的影响。     

网络外部性、转移成本与产品兼容性决策分析

着重研究了提供具有纵向差异产品的新进入企业的兼容性战略决策问题,同时相应地研究了在位企业的兼容性动机.在分析中,重点考虑了转移成本因素,并通过产品兼容度将消费者的转移成本内生化,得到了新进入企业和在位企业的兼容性决策倾向.在竞争均衡中,网络外部性、转移成本和质量差异度是决定竞争双方市场势力的关键因素.     

网络外部性下质量决策与零售商经营目标选择

在网络外部性市场环境下,为研究制造商质量决策和零售商经营目标策略选择之间的影响机理,构建了制造商质量决策和单零售商群体的演化博弈模型,分析了网络外部性和可变质量成本系数对零售商经营目标选择、制造商质量决策、以及节点企业利润的影响.研究发现,1)当制造商只拥有部分市场决策权力时,其质量决策将受到零售商的经营目标策略调整的影响,而零售商经营目标的策略调整则取决于网络外部性大小.当网络外部性较小时,零售商的经营目标将演化稳定为利润最大化,此时制造商将制定较低的产品质量水平;当网络外部性处在中等水平时,零售商的经营目标将演化稳定为利润最大化和收入最大化的混合目标策略,此时制造商将制定中等产品质量水平;当网络外部性较大时,零售商的经营目标将演化稳定为收入最大化,此时制造商将制定高产品质量水平.2)当网络外部性处在中等水平时,其与可变质量成本对零售商经营目标的选择呈现出交叉影响效应,随着可变质量成本的减小,零售商经营目标策略将从利润最大化策略向混合策略,或者混合策略向收入最大化策略演变.3)网络外部性对制造商产品质量的影响效果与可变质量成本和零售商经营目标选择有关,网络外部性效应的增加并不总是使得产品的质量降低.     

具有产能约束的网络型寡头垄断产业链中企业决策模型研究

从供应链角度研究产能约束往往忽视了企业间的横向竞合关系,本文构建了Stackelberg博弈模型,通过对下游企业采取的两种不同策略的比较,分析了具有产能约束的网络型寡头垄断产业链中企业的决策问题,并分析了网络外部性及价格歧视对企业决策的影响.研究表明:网络外部性对产业链内所有企业的产量决策产生多种影响,但其最终影响具有不确定性;无论下游企业采取竞争策略还是合谋策略,下游企业的均衡产量均相等且采取竞争策略时获得较大产量,而上游企业在中间产品市场采取价格歧视策略将获得更多的收益.     

网络外部性下的企业R&D竞争与合作行为研究

本文将网络外部性函数引入D'Aspremont C和Jacquemin A(1988)的模型中,研究双寡头企业的R&D活动.每个企业首先确定自己的R&D投入,然后在产品市场上进行竞争.在R&D阶段有合作和竞争两种情况,在每种情况下讨论了网络外部性对企业R&D投入、最优溢出、企业利润和社会福利的影响.研究发现,网络外部性增强会导致企业R&D投入和企业R&D合作利润的增加,且企业的R&D行为有助于改善社会福利.     

具有网络外部性特征的企业兼并模式选择

在上游垄断、下游双寡头竞争和上下游均为双寡头竞争的两种市场结构下,基于网络外部性建立了标的企业兼并模式选择模型,分析了被兼并的标的企业以横向兼并和纵向兼并为选择的对策均衡.结论表明,在上游垄断、下游双寡头竞争的市场结构下标的企业兼并模式的选择不受网络外部性的影响,而在上下游均为双寡头竞争的市场结构下网络外部性的强度会影响到标的企业兼并模式的选择.最后,在福利分析的基础上也表明了政府与标的企业在兼并模式选择上存在着直接的利益冲突.     

具有不对称网络规模的寡头市场条件下企业的R&D动机研究

本文运用产业组织理论方法,研究了网络外部性特征产业中具有不对称网络规模的寡头市场条件下,潜在技术主导厂商的R&D决策以及创新动机.重点分析了网络外部性、产品兼容性、溢出对具有不同网络规模厂商的R&D决策及创新动机的影响.研究结果显示:(一)网络外部性的增大(或兼容性的减小)将增进"大"厂商的R&D投资和创新动机,而减少"小"厂商的R&D投资和创新动机.(二)"小"厂商可以通过大幅提高产品质量来克服网络外部性对其产生的负效应,在一定条件下成为市场的主导厂商.(三)溢出削弱了厂商的创新动机,但是跟随"小"厂商可以比跟随"大"厂商从溢出中获得更多的收益.     

C2C共享模式下多边市场均衡机制及定价决策

共享产品的出现增加了新的消费和供给渠道,不仅改变了人们的消费模式,还影响着传统产品的供给消费关系,形成了新的多边市场均衡。由于共享平台的双边市场特征及网络外部性特征,新的多边市场均衡取决于C2C共享模式中主体的主观能动性、共享平台双边市场的外部性及其交互作用。本研究通过感知价值差异识别参与主体差异,在考虑双边市场外部性交互作用的基础上,构建三维Hotelling模型,从共享产品双边市场均衡、共享产品介入下的三方市场均衡(共享消费、传统消费、不消费)两个维度,探索共享产品介入下的共享平台双边市场、产品消费三方市场均衡机制,进而识别共享平台和传统平台的最优定价决策,为共享经济中的参与主体制定相关策略提供依据。研究发现:在C2C共享模式中,潜在需求的开发规模与共享经济中的定价决策密切相关,受平台(共享平台和传统平台)产品拥有量的积极影响,双边市场的感知价值差异和外部性对产品消费决策起到调节作用;共享平台的最优定价决策,与供给市场的外部性、供给者感知价值差异以及供给成本密切相关,与消费市场关系不大;共享平台的最大利润受同类产品定价决策、产品效用,以及供给市场外部性、供给市场感知价值差异的积极影...     

网络外部性下双零售商竞争的演化博弈分析

运用演化博弈理论,分析了在网络外部性环境下,有限理性的零售商在长期的市场竞争演化中,会偏好选择利润最大化行为还是收入最大化行为的问题.首先,在考虑网络外部性因素下,构建了不对称双零售商竞争的演化博弈动态系统.其次,分析了该动态系统中零售商竞争的演化稳定策略,并研究了产品替代性、网络外部性强度和市场保留价格等因素对零售商演化稳定策略的影响.再次,将模型扩展到混合策略情形,研究了零售商行为偏好的演化稳定性,并分析了市场保留价格对零售商行为偏好演化稳定性的影响.最后,通过数值算例,进一步分析和验证了所取得的理论成果.     

高峰期内公交车均衡乘车行为与制度安排

研究早晨高峰期内出行者由郊区住处乘公交车到达市中心工作地的交通行为,所建立的均衡乘车行为模型考虑了时间延误成本和车内拥挤成本,得到了固定需求下的最优发车间隔.在弹性需求下,比较了系统最优、垄断和寡头竞争三种不同制度安排下所导致的公交票价、公交车班次数、公司利润和社会净收益等指标.     

Approximation algorithms for the bus evacuation problem

We consider the bus evacuation problem. Given a positive integer B, a bipartite graph G with parts S and \(T \cup \{r\}\) in a metric space and functions \(l_i :S \rightarrow {\mathbb {Z}}_+\) and \({u_j :T \rightarrow \mathbb {Z}_+ \cup \{\infty \}}\), one wishes to find a set of B walks in G. Every walk in B should start at r and finish in T and r must be visited only once. Also, among all walks, each vertex i of S must be visited at least \(l_i\) times and each vertex j of T must be visited at most \(u_j\) times. The objective is to find a solution that minimizes the length of the longest walk. This problem arises in emergency planning situations where the walks correspond to the routes of B buses that must transport each group of people in S to a shelter in T, and the objective is to evacuate the entire population in the minimum amount of time. In this paper, we prove that approximating this problem by less than a constant is \(\text{ NP }\)-hard and present a 10.2-approximation algorithm. Further, for the uncapacitated BEP, in which \(u_j\) is infinity for each j, we give a 4.2-approximation algorithm.     

A set covering approach to bus stop location

This paper considers the problem of locating bus stops in the context of a set covering problem. Zero-one integer programming models are suggested for use in the location of bus stops on new routes and for use in the location of express bus stops on current routes. The models may be used to locate the minimum number of (express) bus stops required to ensure that no passenger need walk more than a specified distance to reach an (express) bus stop. A modified version of the model is presented which enables the router to locate a specified number of (express) bus stops in such a manner that the total distance walked by all boarders is minimized.     

School bus routing problem: Contemporary trends and research directions

The school bus routing problem (SBRP) is a challenging operations research problem that has been studied by researchers for almost 50 years. SBRP publications address one or more operational sub-problems, including: bus stop selection, bus route generation, bus route scheduling, school bell time adjustment, and strategic transportation policy issues. This paper reviews 64 new SBRP research publications and analyzes them by sub-problem type, problem characteristics and solution approach. The impact of key SBRP characteristics (number of schools, mixed load, fleet mix, service environment, objective and constraints) are discussed and the different solution approaches to the SBRP are summarized by sub-problem type and methodology. We found in recent years, SBRP researchers are examining more complex real-world problem settings, adopting both evolutionary-based and trajectory-based metaheuristic solution approaches, and considering ridership and travel time uncertainty. This review documents recent trends in SBRP research and highlights research gaps and promising opportunities for future SBRP research.     

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.     

Dynamic performance assessment of bus transit with the multi-activity network structure

This paper proposes a multi-activity dynamic network data envelopment analysis model that combines the multi-activity, network and dynamic DEA models to assess the performance in terms of individual activities, individual processes, individual periods and overall operation. The main advantage of this model is that the linkages among activities and processes, the shared inputs among activities and processes, and the carry-over items among periods are included in a unified model. It can provide more appropriate performance measures. An empirical application of 20 bus transit firms in Taiwan for the period 2004–2012 is provided. Based on the operational characteristics of bus transit firms, both desirable and undesirable outputs are also incorporated into this model. The results show that none of the bus transit firms was effective in terms of the operational effectiveness, and the sources of operational ineffectiveness among bus transit firms were different. Over the period 2004–2012, the period-operational effectiveness scores maintained stable variance, the period efficiencies of highway and urban bus services appeared to have similar patterns, and transit bus firms performed well in the consumption process.     

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.     

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.     

"平民市长"王伟成

“为官一任,造福一方。造福什么？造福老百姓。老百姓首先要求得到的是衣、食、住、行等方面的方便和实惠。所谓以民为本,就是要以老百姓的这些日常生活中最基本的需求为本。”     

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.