基于深度强化学习的动态共享单车重置问题研究

共享单车在为城市出行带来便利的同时,也面临着资源分布不平衡问题。针对单车分布动态变化环境下的共享单车重置问题,提出基于强化学习的实时调度策略结构。构建了面向强化学习的共享单车重置问题模型,利用深度确定性策略梯度算法(DDPG)进行求解,以获得实时调度策略。基于实际单车分布数据,构建了调度过程中的环境交互模拟器。最后,利用强化学习在模拟器中进行大规模数据实验,结果表明算法得到的调度策略能提高系统表现,并且效果好于已有方法。     

基于射频技术的商用货车燃油防盗防漏预警系统微探

因商用货车的使用环境较为复杂,使得物流运输阶段的商用货车常常反映出燃油非正常流失的情况,面对这类问题,必须要采取合理化的应对方案,确保商用货车燃油得以保护。论文重点结合射频技术,分析商用货车燃油防盗防漏预警系统的应用,概述其基本的应用优势和思路,确保商用货车运输阶段更加的安全。     

What Makes a Good Cargo Bike Route? Perspectives from Users and Planners

Cargo bikes—bicycles made to carry both goods and people—are becoming increasingly common as an alternative to automobiles in urban areas. With a wider and heavier body, cargo bikes often face problems even in the presence of cycling infrastructure, thus limiting their possibilities of route choice. Infrastructure quality and the route choices of cyclists have been well studied, but often solely based on a quantitative approach, leading to tools such as BLOS (bicycle level of service). With various designs of cargo bikes being used for a wide range of purposes, the route choice of cargo bike users is difficult to generalize. This study combines quantitative and qualitative approaches in order to explore what is important for cargo bike users’ route choice, and how this knowledge can be effectively used for planning. Our results suggest that while some general preferences exist, route choice involves complex dynamics that cannot be fully explained by quantitative measures alone: in addition to understanding “what” is important for cargo bike users, we need to understand “why” it is important. Furthermore, route choice is also influenced by the city context, making a study tailored to the local context essential.     

Why truck distance taxes are contagious and drive fuel taxes to the bottom

This paper analyzes the way in which countries with international and local truck traffic decide to switch from a simple fuel tax system to a dual system of fuel and distance charge taxes. We show what drives a country to switch and how this affects the level of fuel taxes as well as incentives for other countries to also adopt the dual system. The model is partially able to explain the gradual extension of kilometer charging for trucks in Europe. The model also shows that, in the absence of diesel cars, the gradual introduction of kilometer charges will make fuel taxation for trucks virtually disappear and will lead to a system where truck use is (1) taxed mainly based on distance, (2) is taxed too heavily, and (3) where highest distance taxes are expected in transit countries with a strong market position. When the fuel tax must in addition serve as an externality tax for diesel cars, the introduction of distance charges for trucks will give rise to diesel taxes that are lower than the external cost of diesel cars. For trucks, this leads to a sum of diesel taxes and distance charges that are higher than the external cost of trucks.     

基于蚁群算法的码头集装箱卡车路径优化研究

分析了集装箱码头作业流程及其传统作业工艺,提出了使用蚁群算法,以集装箱卡车到达目的地的距离最短为目标．建立集装箱卡车路径优化模型,为码头集装箱卡车寻求出发点与目的地之间的最短路径。实验表明,该方法能有效解决集卡最短路径搜索问题。     

Effects of a mileage tax for trucks

We evaluate the effect of the introduction of a mileage tax for trucks in Switzerland in 2001 on traffic volume and externalities. Using a regression discontinuity design, we find a reduction in overall truck traffic of around 4–6%, no effects on car traffic and time-shifted placebos, suggestive evidence for traffic substitution toward rail, and negative effects on nitrogen oxides at curbside monitors. Complementary estimates on the effects of the German mileage tax and complementary estimates based on the synthetic control method are broadly consistent with our main results, although the latter are not statistically significant. Depending on prevailing levels of transportation costs, mileage tax-induced transportation cost increases may accelerate or reverse spatial economic concentration processes. Such implications for economic geography featured prominently in Switzerland and are a promising area for future research.     

Multi-stakeholders’ assessment of bike sharing service quality based on DEMATEL–VIKOR method

ABSTRACT

Bike sharing is a sustainable mode of urban transportation. Assessing the perceived service quality is essential to improve the development of bike sharing. Most of the existing research evaluates the service quality of bike sharing only from the perspective of its users. This study assesses the perceived quality gap among four different stakeholders including government regulators, platform operators, bike association and users. First, an evaluation criteria system consisting of sixteen criteria obtained from the five dimensions of tangibles, reliability, responsiveness, assurance and empathy is constructed based on a revised service performance model. Thereafter, a hybrid multi-criteria decision-making model that combines Decision-Making Trial and Evaluation Laboratory (DEMATEL) with VIsekriterijumska Optimizacija I Kompromisno Resenje (VIKOR) is proposed. Then, the model is applied to evaluate the service quality of bike sharing in Xi’an City. Finally, some useful suggestions are given to improve the bike sharing service quality from the perspective of multi-stakeholders.     

630E卡车举升限位的并联改造

美国GE公司为小松德莱赛公司生产的电动自卸卡车630E卡车由于长时间满负荷运行,大斗销基孔、主销轴等都已发生过度磨损及变形现象,这样造成卡车大斗在使用过程中,由于车斗货物装载不平衡而发生前后、左右的位移串动,造成举升限位开关的间隙不受控制失效,极容易造成举升缸拔缸事故。发生拔缸后,有时还会砸坏设备上的电器元件,发动机等。本文针对上述问题,对630E卡车举升限位进行技术改造。经过改造后的卡车试验运行良好,改造后没有出现拔缸问题。目前本改造方法已在630E卡车上广泛普及,使用性能良好。     

基于ANSYS的叉车门架结构有限元分析

随着叉车市场竞争的日趋激烈,叉车生产企业必须运用现代设计手段来提高叉车的设计质量。文章分析了叉车门架构件的受力情况,通过建立叉车门架的三维实体造型,利用ANSYS对叉车门架的主要构件进行有限元分析,为叉车门架结构的设计提供依据。     

Simulation of truck arrival process at a seaport: evaluating truck-sharing benefits for empty trips reduction

Empty running of container trucks increases empty miles. With the aim of a reduction in the number of empty-truck trips, this study simulates the truck-sharing idea in a port and also evaluates the positive effects of the changes made. This study develops simulation models for the current process (the current truck arrival process in a seaport) and the proposed process (the idea of truck-sharing). The data for this study are provided by a local port. Simulation results are validated by using real-life data from the port. The simulation results confirm that the truck-sharing idea boosts port transport capacity, and that it can handle the increasing future truck volume effectively. The truck-sharing idea can also account for reduced emissions released from trucks in the port surroundings. The results of the simulation will be useful in persuading port authorities to evaluate truck-sharing initiatives. This study will assist port managers with replies to questions, such as ‘What impact will truck-sharing have on transport capacity expansion?’     

Transferia: solving local pain or bringing global gain?

ABSTRACT

The sustainability of container transferia, a specific type of intermodal terminals located in the vicinity of ports, is analysed in an external cost evaluation. This concept enables transporting large amounts of containers from a port to a transferium, outside the most congested area, by high-frequency barge or rail transport. From this point onwards, the transport is executed by truck or intermodal. The paper presents a case study of maritime-based container transport in Belgium. A geographic information systems-based model compares transport alternatives, regarding their societal impact. The findings suggest that when trucks perform the hinterland transport to transferia instead of direct truck transport to the port, the production of external costs decreases in the port area, but remains stable in the hinterland. However, when intermodal chains can replace these truck services to the transferia, external costs remain limited in the port area, but also decrease in the hinterland in most cases.     

多资源点物资发送计算机车辆调度系统模型

为了解决从多资源点向多需求点发送物资中的运输调度问题,本文提出了一个基于模拟过程的计算机调度系统模型以辅助日常车辆及装卸设备调度决策。其中的模拟过程运用启发式规则分配各车辆的路线。通过该系统运行产生的调度安排可以有效地减少运输和操作费用,并提高设备利用效率,减少车辆的排队等待。     

直击北京车展 2012北京国际汽车展览会商用车板块特别报道

备受社会各界关注的北京车展于4月23日正式掀开了其神秘的面纱。在本刊着重关注的商用车及润滑油板块,包括沃尔沃、奔驰、广汽日野、佩卡、福田、东风商用车、江淮、南京依维柯、大运重卡、美孚在内的多家厂商在车展现场展示了其最新产品。在本刊记者历时两天的媒     

池火灾评价法在集输站场原油罐区安全评价中的应用

介绍了对原油集输站场进行安全评价的意义,指出池火灾评价法是目前安全评价中对易燃易爆装置的一种重要评价方法。通过对原油罐区进行主要的危险危害因素分析,建立了防火堤内池火灾伤害数学模型。应用到某企业集输站场内的原油罐区,当发生池火灾时,根据不同的热辐射入射强度造成的设备损害和人员伤亡情况进行了研究、计算和分析,得出的结论对于集输站场的日常安全管理和火灾事故应急救援机制的建立具有指导意义。     

一种城市垃圾车的智能控制系统设计与开发

基于城市环卫车产业的高速发展和对智能化的迫切需求,本文提出了一种城市垃圾车的智能控制系统开发方案。使用的嵌入式控制器和GPS模块,通过CAN总线和MODBUS通讯协议,完成了对车辆状态信息的实时检测和准确显示,最终实现终端用户对作业车辆的远程监控。     

汽车运输型物流企业规避油价风险的策略研究

燃油成本是汽车运输型物流企业运营成本的重要组成部分,针对目前油价持续上涨的背景,本文提出通过加强路线管理策略、提高装载率策略、市场运作策略及加强内部管理来规避油价上涨给汽车运输型物流企业带来的成本压力,并提出了上述策略下的一些具体措施.     

一种车辆重载运输社会经济影响的评估方法

基于系统动力学(System Dynamics)理论建立公路货运系统的系统动力学模型,通过仿真分析车辆载重程度对货运需求、车辆使用决策、车型演化、车辆运输成本以及路面性能的长期动态作用,继而进行车辆重载运输的社会经济影响评估。最后形成一套完整的公路货运车辆重载运输对社会经济影响的系统化研究方法。基于实例的仿真结果表明,在货运车辆普遍重载的条件下,生产要素价格的变动、路面厚度的提高、路面维修间隔期的改变和公路税费标准的调整均不会对车流轴载水平乃至公路货运系统的运行产生根本性影响。在实施车辆载重限制后,系统行为又表现出以下重要特征:反直观性、远期与近期利益相矛盾、系统绩效受车辆载重标准与产业结构的影响较大。     

Traffic safety and vehicle choice: quantifying the effects of the ‘arms race’ on American roads

The increasing share of light trucks in the USA has been characterized as an ‘arms race’ where individual purchases of light trucks for better self‐protection nevertheless worsen traffic safety for society. This paper investigates the interrelation between traffic safety and vehicle choice by quantifying the effects of the arms race on vehicle demand, producer performance, and traffic safety. The analysis suggests that the accident externality of a light truck amounts to $ 2444 during vehicle lifetime and that 12% of new light trucks sold in 2006 and 204 traffic fatalities could have been attributed to the arms race. Copyright © 2010 John Wiley & Sons, Ltd.     

我国铁路货车检修制度现状及发展趋向

铁路运输是一个传统的行业,至今已经有127年的历史,其货运量占全国总运输量的50%以上。对于铁路运输而言,运输载体货车的情况起着关键性的作用。货车数量的多少、质量和好坏决定着运输能力的强弱。本文重点针对我国铁路货车检修制度的现状和发展趋势进行分析,并且将提出可行性的建议。     

How should heavy-duty trucks be taxed?

This paper develops and implements an analytical framework for estimating optimal taxes on the fuel use and mileage of heavy-duty trucks in the United States, accounting for external costs from congestion, accidents, pavement damage, noise, energy security, and local and global pollution. The analysis allows for endogenous fuel economy, increased auto travel in response to reduced truck congestion, and distinguishes driving by truck type and region. We estimate the optimal (second-best) diesel fuel tax at $1.12 per gallon and implementing it increases welfare by $1.34 billion per annum. Optimizing over both fuel and mileage taxes, and differentiating mileage taxes by vehicle type and region, yields progressively higher welfare gains. The most efficient tax structure involves a diesel fuel tax of 69 cents per gallon and charges on trucks that vary between 7 and 33 cents per mile; implementing this tax structure yields estimated welfare gains of $2.06 billion.