A differential evolution approach for the vehicle routing problem with backhauls and time windows

This paper presents a differential evolution algorithm (DEA) to solve a vehicle routing problem with backhauls and time windows (VRPBTW) and applied for a catering firm. VRPBTW is an extension of the vehicle routing problem, which includes capacity and time window constraints. In this problem, customers are divided into two subsets: linehaul and backhaul. Each vehicle starts from a depot and goods are delivered from the depot to the linehaul customers. Goods are subsequently brought back to the depot from the backhaul customers. The objective is to minimize the total distance that satisfies all of the constraints. The problem is formulated using mixed integer programming and solved using DEA. Proposed algorithm is tested with several benchmark problems to demonstrate effectiveness and efficiency of the algorithm and results show that our proposed algorithm can find superior solutions for most of the problems in comparison with the best known solutions. Hence, DEA was carried out for catering firm to minimize total transportation costs. Copyright © 2013 John Wiley & Sons, Ltd.     

济南市轨道交通规划建设的思考

通过对济南市概况的介绍，引出建设轨道交通的必要性，以济南轨道交通建设规划图为例，提出了济南市轨道交通规划建设的建议与思考，特别提出了泉水保护与轨道交通建设的关系，线路交叉结点的无缝换乘问题及高架线路的隔音降噪问题，可为济南市轨道交通建设提供一定的借鉴。     

关于我国航运企业航运附属公司注册地税务筹划问题的探讨

税收支出是企业经营活动中的一项重要支出。对我国航运企业进行税务筹划研究,有利于降低我国航运企业税负水平,提高我国航运企业的国际竞争力。     

基于战略管理的高等职业院校发展规划文本结构分析

发展规划是高等职业院校实施战略管理的文本。本文从发展规划的文本结构出发,以规划文本设计的内在逻辑与实践逻辑分析为观察视角,分析了高等职业院校发展规划的常见缺陷,提出了发展规划文本编制与修改的若干建议。     

高等职业院校发展规划的战略评估

战略评估是高等职业院校战略管理的重要环节,有效的战略评估有利于战略规划实施的控制。本文提出了战略评估的内涵、性质与类型,分析了战略评估的主要内容与基本方式,梳理了战略评估的程序,针对战略评估中难以把握的若干问题提出了评估工作建议。     

Effect of road width and traffic volume on vehicular interactions in heterogeneous traffic

Highway traffic flow phenomena involve several complex and stochastic variables with high interdependencies. The variations in roadway, traffic and environmental factors influence the traffic flow quality significantly. Capacity analysis of road sections under different traffic and geometric conditions need to quantify the vehicles of widely varying characteristics to a common and universally acceptable unit. Passenger car unit (PCU) is the universally adopted unit of traffic volume, keeping the passenger car as the ‘standard vehicle’ with reference to its static and dynamic characteristics; other vehicles are expressed to its equivalent number in terms of PCUs. The studies carried out in this aspect represent the dynamic nature of impedance caused by a vehicle while moving through a traffic stream. The PCU values recommended by the Highway Capacity Manual are widely applied in many countries; however, their applicability is highly under debate because of the variations in prevailing local traffic conditions. There are several factors that influence the PCU values such as traffic, roadway, vehicle, environmental and control conditions, etc. Apart from vehicular characteristics, the other two major factors that influence the PCU of vehicles are the following: (i) road width and (ii) traffic volume. In this study, estimation of PCU values for the different types of vehicles of a highly heterogeneous traffic on 7.5‐ and 11.0‐m‐wide roads, using micro‐simulation technique, has been dealt with. It has been found that the PCU value of a vehicle type varies significantly with variation in road width and traffic volume. The results of the study indicate that the PCU values are significantly influenced by the said two factors. Copyright © 2012 John Wiley & Sons, Ltd.     

利用激光点云的城市无人驾驶路径规划算法

为了解决随机采样算法受感知环境不确定性影响下的弱鲁棒性以及弱可靠性问题，采用一种基于激光空间势场的渐优随机采样算法框架来设计符合无人驾驶需要的规划算法。针对感知环境的不确定性，首先基于势场原理与激光障碍物点云构建一个融入了斥力场的规划空间，解决激光障碍物提取中的过分割等问题。其次，利用规划空间来处理随机采样算法中的采样策略、最优母节点选取策略、修剪策略以及最终路径选择策略。再次，在算法中加入了Anytime策略来提高优化解的利用率，使得算法的计算效率满足无人驾驶实时性的要求。同时，为了保证无人驾驶中规划路径的鲁棒性与可靠性，创建了一个综合5重因素的代价函数来选择最优路径，并根据不同的无人驾驶场景来调整相对应的参数；最后在城市测试道路上进行了实地测试。结果表明：设计的算法框架能够适应最高时速40 km·h^-1的城区驾驶环境，并能完成跟驰、换道、融入以及静动态障碍物的避障决策。在与SST算法的对比试验中，所提出的算法在各个试验中的轨迹、方向盘转角以及速度的平滑性都优于SST算法，其轨迹与障碍物的距离也优于SST算法。     

具有值机功能的轨道交通机场线车站布局方案

近年来,随着国内机场客流量的高速增长及城市轨道交通建设步伐的加快,各大、中城市也开启了轨道交通机场线的建设。结合国内外机场提前值机的概念,以西安北客站至咸阳国际机场的轨道交通机场线为例,分析了值机客流的特征,研究了具备提前值机功能的轨道交通机场线车站布局的3个可行性方案,并指出了实现机场功能外移所存在的问题。     

Scenario construction for transport planning

This paper argues that the types of uncertainty having the most serious consequences for transport planning are not captured by existing modelling procedures, which typically rely on a limited amount of sensitivity testing of plans based on extrapolative forecasts. It recommends as an alternative scenario‐based planning, an approach which is finding increasing application in private sector policy formation. The paper summarises the origins of scenario planning and the gradual broadening in its range of application, before going on to suggest methods of scenario construction suitable for transport planning applications. It considers the arguments for and against associating probabilities with scenarios and also addresses the problems of formulating transport strategies and evaluating them within the context of a scenario‐based approach to strategy choice.