预约出行模式展望

城市交通系统中，由于供需时空不匹配，在一些瓶颈点前会产生较严重的拥堵排队现象。 虽然出行者最终都能完成出行，但是在瓶颈点前的拥堵和排队给出行者带来了额外的等待时 间。理想情况下，如果每个出行者都按照其实际通过的时刻到达瓶颈点，就可以减免在瓶颈点前 拥堵和排队产生的等待时间，即把在途拥挤排队时间转变为在家等待时间，而这两类时间的价值 在出行广义费用函数中有较大差异。在传统交通系统中，由于缺乏信息指引，出行者只能依靠在 路上排队获得瓶颈点的通行权。随着即时通讯、人工智能等新兴技术发展，可通过技术手段事先 为出行者排好通过瓶颈点的顺序，并将推算出的通过时刻告知出行者，出行者按照该时刻到达便 可无等待通过瓶颈点。基于此，本文提出预约出行的交通组织模式，即借助于创新科技手段，在 城市交通系统中利用预约将现场的拥堵排队转变为虚拟的线上排队，引导出行者按照实际能够 通过的时刻到达瓶颈点。研究认为：预约出行可以在一定程度上缓解出行供需时空不匹配问题， 在有限资源条件下减少在途排队，提高未来城市交通系统运营组织和管理的水平。     

服役转臂节点刚度对运营车辆动力学影响研究

运用SIMPACK软件建立CRH3型高速动车组模型,结合试验获得服役120万km转臂节点刚度变化范围,在考虑2种抗蛇行减振器、3种磨耗踏面与3种钢轨廓形匹配的实际运营工况下,仿真分析服役转臂节点刚度变化对车辆动力学性能的影响。结果表明:120万km服役转臂节点纵向刚度分布范围为90~150 MN/m,主要变化率在-10%~0%之间。在服役转臂节点刚度变化范围内,增大转臂节点纵向刚度可以降低车辆非线性临界速度及运行平稳性,并增大轮轨磨耗,其影响程度与轮轨匹配关系以及抗蛇行减振器种类关系紧密。为保证车辆运行稳定性及平稳性,建议避免使用60N(min-wear)钢轨,适当减小转臂节点刚度以及使用T60抗蛇行减振器。     

Transit stop inspection and maintenance scheduling: A GPU accelerated metaheuristics approach

Bus stops are integral elements of a transit system and as such, their efficient inspection and maintenance is required, for proper and attractive transit operations. Nevertheless, spatial dispersion and the extensive number of bus stops, even for mid-size transit systems, complicates scheduling of inspection and maintenance tasks. In this context, the problem of scheduling transit stop inspection and maintenance activities (TSIMP) by a two-stage optimization approach, is formulated and discussed. In particular, the first stage involves districting of the bus stop locations into areas of responsibility for different inspection and maintenance crews (IMCs), while in the second stage, determination of the sequence of bus stops to be visited by an IMC is modelled as a vehicle routing problem. Given the complexity of proposed optimization models, advanced versions of different metaheuristic algorithms (Harmony Search and Ant Colony Optimization) are exploited and assessed as possible options for solving these models. Furthermore, two variants of ACO are implemented herein; one implemented into a CPU parallel computing environment along with an accelerated one by means of general-purpose graphics processing unit (GPGPU) computing. The model and algorithms are applied to the Athens (Greece) bus system, whose extensive number of transit stops (over 7500) offers a real-world test bed for assessing the potential of the proposed modelling approach and solution algorithms. As it was shown for the test example examined, both algorithms managed to achieve optimized solutions for the problem at hand while there were fund robust with respect to their algorithmic parameters. Furthermore, the use of graphics processing units (GPU) managed to reduce of computational time required.     

基于客户分类的即时配送路径优化研究

大数据背景下即时配送平台对客户进行精细化管理已成为可能.为寻求企业长期发展，将客户分类融入到车辆路径问题中，用有限的资源提高配送准时性以得到优质客户的维持和发展，为企业赢得更多潜在效益.本文结合客户的消费行为将客户分为多个层级，根据每层级客户的特点设置超时惩罚成本，构建出基于客户分类的即时配送路径优化模型，并根据问题特点设计遗传算法求解，最后，结合某即时配送平台的业务场景进行案例分析，验证了模型和算法的有效性.     

A semi-analytical approach for solving the bottleneck model with general user heterogeneity

This paper proposes a novel semi-analytical approach for solving the dynamic user equilibrium (DUE) of a bottleneck model with general heterogeneous users. The proposed approach makes use of the analytical solutions from the bottleneck analysis to create an equivalent assignment problem that admits closed-form commute cost functions. The equivalent problem is a static and asymmetric traffic assignment problem, which can be formulated as a variational inequality problem (VIP). This approach provides a new tool to analyze the properties of the bottleneck model with general heterogeneity, and to design efficient solution methods. In particular, the existence and uniqueness of the DUE solution can be established using the P-property of the Jacobian matrix. Our numerical experiments show that a simple decomposition algorithm is able to quickly solve the equivalent VIP to high precision. The proposed VIP formation is also extended to address simultaneous departure time and route choice in a single O–D origin-destination network with multiple parallel routes.     

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行程时间的不确定性是影响货运车队路径选择的一个重要因素，特别是对于要求货物准时送达的配送任务（例如商品混凝土的配送），提出了在车辆调度中考虑由拥挤路段交通流量波动引起的行程时间不确定性的方法，建立了考虑行程时间可靠性要求的车辆优化调度数学模型，给出了相应的启发式算法，通过算例介绍了该模型和算法的应用。结果表明配送总成本随行程时间可靠性要求的提高而增加。     

The Vehicle Routing Problem: The Case of the Hong Kong Postal Service

Abstract

With the growth in population and development of business activities in Hong Kong, the range and level of services provided by Hongkong Post have multiplied. However, the schedule of its postal vehicles, including mail collection and delivery, is still constructed manually on a daily basis, based on the experience of staff and transportation reviews. In this paper, the problem of scheduling a set of n collection points (District Post Offices) from a depot (General Post Office) in Hong Kong Island is addressed. The objectives pursued are the maximization of resource utilization and minimization of operation costs. In other words, the variable cost is expected to be reduced. To achieve these goals, an integer linear programming (IP) model of the vehicle routing problem (VRP) is developed in an effort to obtain optimal solutions. As the model involves computational complexity, a commercial software package CPLEX is used to solve the problems efficiently. The results show that the proposed model can produce optimal vehicle routes and schedules.     

隧道施工安全问题探讨

由于山区特殊的地质条件,隧道成为了山区高等级道路重要的组成要素.鉴于隧道工程的特殊性和重要性,隧道安全施工不容忽视.重点介绍隧道施工前的准备工作、隧道支护和衬砌的注意事项,以期为隧道施工提供参考.     

下穿黄河陡坡小断面隧道快速施工及设备配套技术

油气管道穿江过河隧道普遍采用断面小、坡度大的结构形式,及其下穿江河、水患风险巨大的特点,成为该类隧道施工需要克服的重要难题。如何确定其合理的施工方案及设备配套,是决定其生产效率与施工效果的关键所在。以西气东输中卫黄河隧道穿越工程为题材,通过对其施工方案及设备选型配套技术的研究、分析,提出了适用于该类型隧道工程的施工方案与设备配套技术,确保了隧道安全、快速施工。