考虑第三方物流竞争的第四方物流运输与库存外包决策

第四方物流在物流外包中的主导地位和第三方物流在提供服务时基于配送频率的竞争对物流外包产生重要影响。针对这一问题,本文建立基于价格、配送频率和需求分配比例的三阶段非合作动态决策模型和库存运输联合优化模型(ITIO)来分析4PL主导的业务外包和3PL之间的竞争,通过对比两个模型来分析决策权对个体和系统绩效的影响,并用算例验证了文章的结论。研究表明,在3PL同质且需求分配比例为0.5时,三阶段非合作动态决策模型的配送频率比ITIO最优值小29%,库存持有成本比ITIO最优值高41%,物流配送成本比ITIO最优值小21%,总成本比ITIO最优值大9%。库存运输联合优化模型虽然具有一定成本优势,但是其过分强调协调不利于3PL之间的竞争和提高。     

易腐性产品运输设施选择博弈

易腐性产品的价值会随着时间的流逝而逐渐损失,多个客户可以联合使用某种运输设施时,如何对费用进行公平且稳定的分摊是合作能否进行的基础.把易腐性产品的损失价值和运输费用之和作为总费用,进而将易腐性产品的运输设施选择的费用分配问题构造成运输设施选择合作博弈,证明了在易腐性产品负指数价值损失的情况下,运输设施选择博弈的核心非空,且为凹博弈,并讨论了解的特征.论文还证明具有附加运输费用的运输设施选择博弈的核心非空,分析了核心与线性规划松弛的对偶最优解之间的关系.论文对有约束设施选择博弈进行了分析,并提出了进一步研究的方向.     

基于风险的考虑成本和允许等待的车辆运输调度问题研究

本文同时考虑了成本约束和允许等待情形,研究了最小化风险的车辆运输调度问题,其中运输风险是随时间不同而变化的,即研究在时间依赖网络中基于风险的有约束的运输路径选择问题,以及在选定路径的顶点上决定的出发和等待时间的综合问题。建立了相应的混合整数规划模型,设计了相应的算法,并分析了算法复杂性,最后通过算例验证了该算法的有效性和可行性。     

城市交通中利用Gram-Charlier分布估计行程时间可靠性

行程时间可靠性近年来成为交通领域重点关注的问题,但现有方法在反映当前行程时间的尖峰厚尾特征方面已表现出与实际情况的较大差异,因此本文针对这一弱点,结合数据收集的难易,设计了一种新颖的栅格行程时间预测方法,可以全面考虑车辆的行驶和等待时间,然后引入了可以反映更多行程时间信息的Gram-Charlier分布函数,作为行程时间可靠性的研究手段,同时对分布参数给出了两种计算方法.仿真结果表明,本文提出的方法能很好体现当前城市交通行程时间的易变性特点.     

海上集装箱运输中轴辐式航线结构的经济性分析

本文通过对海上集装箱运输中轴辐式航线结构与直达航线结构的运输成本与密度经济和范围经济指标的比较分析,说明:增加密度经济效应是轴辐式航线结构采用的动因,存在范围经济是其采用的条件.同时.对轴辐式航线结构经济性的影响因素以及提高途径进行了分析,还对当前海上集装箱运输中轴辐式航线结构越来越广泛采用的原因进行了解释.     

双积分政策下传统能源车企的策略选择研究

双积分政策的实施迫使传统能源车企必须考虑采用何种策略调整运营决策,然而现有研究无法为其提供策略选择指导。本文在双积分政策背景下分别构建传统能源车企采用购买、关联和投产策略下的最优决策模型,通过不同模型的解析对比和数值案例分析,研究该政策对传统能源车企的影响并寻求为其提供策略选择指导。研究结果表明双积分政策的实施会减少传统能源汽车的产量并降低传统能源车企的利润;传统能源车企应关注积分价格和新能源汽车积分比例要求;若与新能源车企达成较低的积分内部协议价,则传统能源车企采用关联策略最优;若协议价较高,当积分市场价较低时采用购买策略最优,否则在关联企业积分盈余情况下采用关联策略最优;若考虑投产策略,当积分市场价格较高时可以获利更多,而当积分市场价格较低时采用购买策略更好。     

小麦高产栽培途径生理基础研究——光合生产与产物运输

在肥力水平较高条件下,对不同行距和基本苗小麦光合生产与产物运输能力的比较生理学研究和诸项生理指标的生物统计学分析表明,宽行稀播小麦后期群体内光照改善,个体和群体生产力得以协调发展,光合生产能力增加,产物运输速率提高是小麦“高肥宽行稀播”高产栽培途径的重要生理学基础。     

The Effect of Distribution Processes on Replenishment Lead Time and Inventory

We investigate the interrelationship of distribution center picking policies and supply chain inventory performance. In particular, we show how the picking sequence in the upstream supply chain link affects the inventory levels of items being replenished to a downstream link for a common “ship‐when‐full” trailer dispatching policy. Perturbing the picking sequence affects items’ inventory levels asymmetrically which causes the aggregate system inventory to vary. We separate the items in replenishment into those units in transit and those awaiting shipment from the upstream distribution step: we call the latter the residual replenishment. We show that the process governing aggregate residual replenishment is Markov and has a stationary distribution that is discrete uniform. Computing the item‐level residual distribution is intractable and so we develop analytical models from which we derive hypotheses for the effectiveness of stable vs. random picking sequences, how item residual replenishment varies with stable picking sequences, and how the aggregate inventory level changes with picking sequence. These suggest a heuristic sequencing algorithm for minimizing inventory, which performs well in simulation tests over a large testbed of parameter sets.     

Building an Integrated Research/Policy Planning Age-Friendly Agenda

This article describes an innovative model for integrating research into a policy and planning agenda aimed to help neighborhoods become more supportive of older adults. Philadelphia Corporation for Aging (PCA) established Age-Friendly Philadelphia (AFP) to catalyze efforts to improve the physical and social environments for seniors. The Research Program at PCA became an important part of this effort by providing multiple types of supports to PCA staff and other stakeholders. Most notably, the research program worked with planners to adopt the United States Environmental Protection Agency's Aging Initiative model for Philadelphia. That model focuses on (1) staying active, connected, and engaged; (2) development and housing; (3) transportation and mobility; and (4) staying healthy. Examples of practice efforts actualized using this research are also presented. By developing a new approach to the way research can support practice initiatives, AFP has been able to increase its effectiveness, and researchers have found better ways to work collaboratively with professionals in policy, planning, and practice. The PCA model should be considered as a framework for similar efforts aimed at creating age-friendly communities.