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A dynamic model of integrated production-transportation operations.

机译：集成的生产-运输运营的动态模型。

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摘要

The Integrative Freight Market Simulation (IFMS) aims at developing a comprehensive urban freight transportation demand model, which includes three key dimensions of the freight system: (1) financial, by focusing on profit maximization; (2) commodity flows, that represent demand; and (3) vehicle trips, the logistical response of the supply side to satisfy consumer demands. This thesis focuses on the development of analytical formulation to estimate urban freight-related flows for integrated shipper-carrier operations in the IFMS framework. It was assumed that the market is composed of two key agents: suppliers and consumers. The suppliers perform both shipping and transportation functions. The suppliers are profit maximizers who produce, sell and deliver a generic commodity. The consumers are receivers with a fixed demand for the same commodity. The problem studies how the suppliers adjust production level, profit margin, and routing strategy in response to the competition, until Walrasian equilibrium is reached satisfying the following conditions: (1) the suppliers' profits are maximized, they are not able to earn more by changing their own business strategies; (2) the consumer demands are satisfied; and (3) the market clears, and no inventory is left.;The solution methodology used heuristics to iteratively solve the problem to ensure equilibrium. At each time period, the problem consisted of three stages. The first stage, termed "target", considered the sequence of decisions by which the suppliers decide how much to provide and deliver at what price based on their expectations of how much to sell in the market, this included the decisions of production level, profit margin, preliminary routing, as well as the estimation of total cost and price. A set of dynamics was used to help the suppliers make decisions on the productions for the next time period. The second stage was the market competition, which determines the amount that each consumer will purchase from the suppliers. This was formulated by a logit function of price to determine the market share. The third stage was termed "observed", during which the suppliers route the vehicles, make the deliveries, and estimate the performance metrics.;The algorithmic solutions were obtained for three types of dynamics of the suppliers' decisions on productions. For small problems, the suppliers tended to find their optimal routing and profit margins relatively quickly, thus the solutions generally converged to equilibrium relatively fast. At equilibrium, the suppliers with proximity to the market generally had lower marginal cost and charged higher profit margin, thus they yielded higher net profits; while those farther away usually gained lower profits and even lost money. Furthermore, if the consumers are less price sensitive, the suppliers could charge higher profit margins. For larger problems, the suppliers generally kept changing routing pattern and profit margin, and then it was more difficult to converge to equilibrium, in fact equilibrium may not exist. The analysis of market entry and exit indicates that, market proximity is important if there is significant locational difference. If locational difference is only marginal, then routing plays a significant role.
机译：综合货运市场模拟（IFMS）旨在开发一个综合的城市货运需求模型，该模型包括货运系统的三个主要方面：（1）通过关注利润最大化来实现财务； （2）代表需求的商品流动； （3）车辆出行，即供应方的后勤响应，以满足消费者的需求。本文着重于分析公式的开发，以估计在IFMS框架中综合与托运人/承运人业务有关的城市货运相关流量。假定市场由两个主要代理组成：供应商和消费者。供应商同时履行运输和运输职能。供应商是生产，销售和交付通用商品的利润最大化者。消费者是对相同商品有固定需求的接收者。该问题研究供应商如何根据竞争情况调整生产水平，利润率和路线策略，直到达到瓦尔拉斯均衡并满足以下条件：（1）供应商的利润最大化，他们不能通过以下方式获得更多利润改变自己的商业策略； （2）满足消费者需求； （3）市场畅通，无库存。解决方法采用启发式迭代地解决问题，以确保均衡。在每个时间段，问题包括三个阶段。第一阶段称为“目标”，考虑了供应商根据对市场销售量的期望来决定以多少价格提供和交付多少商品的决策顺序，其中包括生产水平，利润的决策。利润，初步路由以及总成本和价格估算。使用了一组动力来帮助供应商在下一个时间段内对生产做出决策。第二阶段是市场竞争，它决定了每个消费者将从供应商那里购买的金额。这由价格的对数函数确定市场份额。第三阶段被称为“观察”阶段，在此阶段中，供应商对车辆进行路线安排，进行交付并评估绩效指标。；针对供应商对生产决策的三种动态变化，获得了算法解决方案。对于小问题，供应商往往会比较快地找到他们的最佳路线和利润率，因此解决方案通常会比较快地收敛到均衡。处于均衡状态时，接近市场的供应商通常具有较低的边际成本并收取较高的利润率，因此产生了较高的净利润。而距离较远的人通常获得较低的利润，甚至亏损。此外，如果消费者对价格的敏感性降低，则供应商可以收取更高的利润率。对于较大的问题，供应商通常会不断改变路由模式和利润率，然后更难以收敛到平衡，实际上可能不存在平衡。市场进入和退出的分析表明，如果位置差异显着，则市场接近性很重要。如果位置差异仅是很小的，那么路由将发挥重要作用。

著录项

  • 作者

    Xu, Ning.;

  • 作者单位

    Rensselaer Polytechnic Institute.;

  • 授予单位 Rensselaer Polytechnic Institute.;
  • 学科 Engineering Civil.;Transportation.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 179 p.
  • 总页数 179
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 建筑科学;综合运输;
  • 关键词

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