带时间窗的卡车编队路径优化

卡车编队是一种极具前景的新型运营组织模式，多辆采用半自动驾驶技术的卡车以较小的车头间距共同行驶，达到减少能源消耗与环境污染和保障交通安全的目的，该组织模式也被称为“公路列车”。从运营管理及调度技术的角度进行研究，利用商品网络流理论解决某一特定卡车在何时何地编入哪个卡车编队的问题，尽可能地促进卡车编队的形成，最大限度地节约能源。本文分析卡车编队形成过程中额外产生的集结等待时间，并量化计算由于卡车编队成组运行，空气阻力的下降进而产生的燃油节省。在限制卡车编队规模的条件下，构建考虑合理绕行的卡车编队路径优化模型，将每个运输任务是否通过路网中的弧段设置为决策变量，优化结果既能反映每个弧段上卡车编队的构成情况，又能体现每个运输任务具体的走行路径。采用商业软件求解构建的卡车编队路径优化模型，形成卡车编队19个，节省燃油费用达到14%以上。结果表明：该 模型能得出理想的卡车编队路径优化方案，为卡车编队的推广应用提供理论参考。     

On activity-based network design problems

This paper examines network design where OD demand is not known a priori, but is the subject of responses in household or user itinerary choices to infrastructure improvements. Using simple examples, we show that falsely assuming that household itineraries are not elastic can result in a lack in understanding of certain phenomena; e.g., increasing traffic even without increasing economic activity due to relaxing of space–time prism constraints, or worsening of utility despite infrastructure investments in cases where household objectives may conflict. An activity-based network design problem is proposed using the location routing problem (LRP) as inspiration. The bilevel formulation includes an upper level network design and shortest path problem while the lower level includes a set of disaggregate household itinerary optimization problems, posed as household activity pattern problem (HAPP) (or in the case with location choice, as generalized HAPP) models. As a bilevel problem with an NP-hard lower level problem, there is no algorithm for solving the model exactly. Simple numerical examples show optimality gaps of as much as 5% for a decomposition heuristic algorithm derived from the LRP. A large numerical case study based on Southern California data and setting suggest that even if infrastructure investments do not result in major changes in link investment decisions compared to a conventional model, the results provide much higher resolution temporal OD information to a decision maker. Whereas a conventional model would output the best set of links to invest given an assumed OD matrix, the proposed model can output the same best set of links, the same daily OD matrix, and a detailed temporal distribution of activity participation and travel from which changes in peak period OD patterns can be observed.     

一种基于时空距离的带时间窗车辆路径问题算法

带时间窗的车辆路径问题是典型的NP难题,一种常用的求解方法是先对顾客分组,后进行路径优化的两阶段启发式算法. 传统算法在顾客分组时主要考虑顾客的空间位置关系,但是忽略了顾客对服务时间窗口的要求. 本文同时考虑顾客的时间和空间特性,提出了一种基于时空度量的顾客分组方法. 在路径优化阶段,本文提出了一种禁忌搜索算法来进行求解,该算法中禁忌的对象不是解,而是这些解的目标函数值的区间,以便于提高收敛效率. 作为验证,本文以Solomon标杆问题集为算例进行演算,结果表明,在窄时间窗约束下,基于时空距离的两阶段启发式算法明显优于基于空间距离的算法,且部分算例的解达到了国内外已发表的最好解.     

基于VBA的机车交路图计算机辅助绘图系统研究

机车交路图是铁路组织列车运行的基础性文件,采用AutoCAD的原始制图命令进行制图操作,效率较低且容易出错.本文采用AutoCAD VBA二次开发,开发了基于参数输入的机车交路图计算机辅助绘图系统,实现了机车交路图的快速生成和修改.     

车辆数目未知的带时间窗口的车辆路径混合遗传算法

研究带时间窗口的车辆路径问题(VRPTW),主要考虑车辆容量约束、时间窗口约束、最大距离等约束,且完成配送所需的车辆数目不确定,要求在车辆数目最少的条件下再使总的行驶路径最短.用基于邻域搜索的混合遗传算法求解该问题,该算法既具有遗传算法的全局搜索能力,又具有邻域搜索算法的局部搜索能力.在求解过程中,设计新的前置交叉算子进行遗传操作,然后进行互换和逆转等邻域操作.应用MATLAB语言编程进行模拟计算,结果表明该混合遗传算法明显增强了群体演化的质量,提高了算法收敛速度,较好地解决了早熟收敛问题.     

混合超启发式法求解大规模VRP的优化研究

车辆路径是一类NP(non-deteministic polynomial)完全问题,研究解决车辆路径问题的高质量启发式算法有着重要理论价值和现实意义.提出一种将最近邻搜索法和禁忌搜索法优势相结合的混合超启发式算法,用来解决带容量约束的车辆路径问题.先利用最近邻搜索法构建初步路线,再利用禁忌搜索法对内部线路和互跨线路进...     

警戒区水上交通冲突数据自动采集系统

基于ECDIS、AIS以及支持向量机,引入交通冲突研究方法,提出船舶定线制警戒区水上交通冲突数据自动采集解决方案.方案利用支持向量机学习训练冲突样本数据,得到判别冲突严重程度SVM分类模型,并将SVM软件包和SVM分类模型嵌入到ECDIS,结合实时AIS数据建立水上交通冲突数据自动采集系统,应用该系统对长江口船舶定线制...     

绿色船舶的营运选择(英文)

Environmental issues and rising fuel prices necessitate better energy-efficiency in all sectors.The shipping industry is one of the major stakeholders,responsible for 3% of global CO2 emissions,14%-15% of global NOX emissions,and 16% of global SOX emissions.In addition,continuously rising fuel prices are also an incentive to focus on new ways for better energy-effectiveness.The green ship concept requires exploring and implementing technology on ships to increase energy-efficiency and reduce emissions.Ship operation is an important topic with large potential to increase cost-and-energy-effectiveness.This paper provided a comprehensive review of basic concepts,principles,and potential of operational options for green ships.The key challenges pertaining to ship crew i.e.academic qualifications prior to induction,in-service training and motivation were discussed.The author also deliberated on remedies to these challenges.     

存货影响销售率的无形变质物品库存-运输整合优化模型

针对供应商采购量与存货水平临界点数量关系的两种情况,主要研究物品无形变质与存货影响销售率现象对库存补充策略和运输费用的影响,进一步探讨库存-运输整合优化问题。在物品发生无形变质并允许缺货的条件下,建立了供应商的库存-运输整合优化模型,讨论了存货影响销售率现象对库存更新周期、订货批量、平均库存与运输总成本的影响,得到了供应商的最优库存更新周期和最佳订货批量。最后,通过算例进行实证研究,为供应商在无形变质物品的库存-运输整合决策中提供了借鉴与参考。     

多频无线通信网路由协议

针对多频无线通信网的特点,设计了一种多频无线通信网路由协议（MCWN-RP）.协议采用组播扩散机制优化扩散路径,采用非重传确认机制减少报文种类,采用最短路径树构造算法降低扩散内容,采用自适应定时器调整机制减少网络冲突,从而大大降低了协议开销;同时采用差别拓扑更新方式,提高收敛性能.对MCWN-RP进行了协议开销和收敛时间的性能分析,得出协议性能与拓扑更新包大小和协议包发送间隔的关系.OPNET仿真结果表明,与OSPF、OLSR协议相比,MCWN-RP具有非常小的协议开销和较高的收敛性能,是一种高效的动态路由协议.