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参考永续盘存法,给出客运交通行业资本存量的计算模型,然后以北京市城区为例,分别计算了2000年和2005年北京市城区道路基础设施、交通管理设施、公共交通场站、停车场、轨道交通基础设施、各客运车辆等资本存量。结果表明,北京市在“十五”期间交通基础设施资本存量、车辆资本存量两者增速基本上保持一致,交通基础设施资本储备加大,顶住了车辆保有量增加的压力。同时,本文认为客运交通资本存量,是道路长度、车辆保有量、停车场泊位数等基础设施供给能力与车辆供给能力的综合货币表现,可作为了解、评价至某时间、此地区交通供给能力的综合指标之一。     

带折扣的多阶段库存系统的优化算法

针对供应商提供数量折扣、需求率随时间变化、周期性检查并补充库存的多阶段库存控制策略，提出一种优化算法．该算法以各时段的累计需求为根节点建立搜索树，从而将带折扣的库存问题转化为典型的动态批量问题，运用动态规划法即可求解．利用该算法可以找出在计划时段内总成本最小的补充策略．用算例说明了该算法的有效性．     

制造/再制造混合系统的最优生产批量模型

为了确定制造／再制造混合系统的最优生产批量，假定需求率和回收率是连续、确定的，以单位时间内新产品和再制造产品的订购费以及回收件和可用件的存储费之和最小为目标，建立了新产品制造和回收件再制造的最优批量模型．为保证批次是正整数，给出了批量计算结果的简单修正方法．该模型不仅适用于再制造生产率有限和无限的情形，而且适用于制造生产率有限和无限的情形．算例结果验证了该模型的有效性．     

供应商选择问题的不确定优化模型及其算法

应用了不确定性模型描述供应商选择问题,建立了多目标随机机会约束规划的模型.设计了解决这类问题的混合智能算法;并通过实例计算表明:不确定性优化模型及混合智能算法是解决供应商选择等这类不确定性智能商业问题的有效办法,具有广泛的应用前景.     

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库存在配送系统优化过程中影响甚大,过高的库存或库存不足均会对配送系统造成不良影响。研究了连锁零售配送系统的配送中心和门店的两级库存水平和订货策略问题。通过在数学解析模型的优化结果基础上,应用三维可视化离散事件仿真方法建立了在FLEXSIM软件平台上的配送系统的仿真模型,并结合约束理论与系统仿真对仿真过程进行优化,缩减了仿真方案的数量和提高了仿真的效率并得到优化的仿真方案。研究结果表明,基于整合约束理论的三维可视化仿真是可以提高仿真效率并增强仿真交互性的有效方法。     

铁路局现车管理和货车追踪系统的设计与实现

结合目前铁路计算机生产网络布局、运输生产力布局和车站信息系统建设状况,根据铁路局、运输站段对现在车管理和贷运监控、追踪的需求,介绍系统的设计思路、信息集成和实施方案以及系统的组成和主要功能、技术特点,给出了系统的实施成效.     

策略性库存路线的PPSA算法

总结了Larson的SIRSA(Strategic Inventory and Routing Saving Algorithm)启发式解法,针对其补充周期短的缺陷,提出了以库存补充周期和补充阶段为变量的PPSA(Period and Phase Saving Algorithm)启发式解法。计算结果表明,当车辆每作业一次能补充的客户数较多,且客户间最大的可能补充时间间隔差别较大时,PPSA算法对车辆的需求明显少于SIRSA算法。     

基于信息一体化VMI模式的军事物流配送研究

文章首先介绍了一种新的库存管理方法—供应商管理用户库存（Vendor Managed Inventory）,并分析了目前我军的装备物资配送现状;然后在此基础上提出了基于信息一体化的军事配送中心管理库存模式,将其划分为需求预测模块和配送计划模块,并规划了系统的工作流程;最后介绍了该系统的三种技术支持。     

Fuzzy modeling approach to the rail freight car inventory problem

Techniques to improve freight car fleet use are of considerable interest to the railroad industry. In this paper, we present a fuzzy inventory control approach applied to the sizing of empty cars on a rail network. We address the problem of deciding the optimal inventory level and the optimal ordering quantity for a rail freight car fleet system in which demand and travel time are uncertain variables represented as triangular fuzzy numbers. Based on the fuzzy economic order quantity (EOQ) formula, a modified fuzzy EOQ model is set up and the optimal policy is developed using the signed distance method to defuzzify the fuzzy total cost. Computational results made for the Serbian rail network case verify the proposed model as well as the efficiency of the approach.     

Dynamic calculation of ship exhaust emissions based on real-time AIS data

The activity-based methodology is becoming an increasing way to calculate exhaust emissions from ships in a port. Existing studies make great effort to build and analyze ship emission inventory in a variety of ports by applying this method to historical ship trajectory data. This kind of static emission inventory however, cannot meet the needs of real-time ship emission monitoring. This article proposes a method of dynamic calculation of ship exhaust emissions based on real-time ship trajectory data. Firstly, real-time ship AIS messages are partitioned into continuous data blocks and go through a series of pre-processing operations, including trajectory extraction, association and interpolation. Ship activity parameters are then determined by database querying and regression analysis based on ship attributes. Subsequently, an improved activity-based methodology is employed to estimate exhaust emissions from ships in a distributed way. Based on the grid model, regional ship exhaust emissions can be statistically and dynamically calculated by the spatial allocation of all ship emissions. In a case study, a real-time monitoring platform for ship exhaust emissions in Shenzhen port is developed to demonstrate the effectiveness of the proposed method.