Well-to-wheel costs,primary energy demand,and greenhouse gas emissions for the production and operation of conventional and alternative vehicles

This study provides a comprehensive comparison of well-to-wheel (WTW) energy demand, WTW GHG emissions, and costs for conventional ICE and alternative passenger car powertrains, including full electric, hybrid, and fuel cell powertrains. Vehicle production, operation, maintenance, and disposal are considered, along with a range of hydrogen production processes, electricity mixes, ICE fuels, and battery types. Results are determined based on a reference vehicle, powertrain efficiencies, life cycle inventory data, and cost estimations. Powertrain performance is measured against a gasoline ICE vehicle. Energy carrier and battery production are found to be the largest contributors to WTW energy demand, GHG emissions, and costs; however, electric powertrain performance is highly sensitive to battery specific energy. ICE and full hybrid vehicles using alternative fuels to gasoline, and fuel cell vehicles using natural gas hydrogen production pathways, are the only powertrains which demonstrate reductions in all three evaluation categories simultaneously (i.e., WTW energy demand, emissions, and costs). Overall, however, WTW emission reductions depend more on the energy carrier production pathway than on the powertrain; hence, alternative energy carriers to gasoline for an ICE-based fleet (including hybrids) should be emphasized from a policy perspective in the short-term. This will ease the transition towards a low-emission fleet in Switzerland.     

Electric vehicles and the urban environment

Abstract

Due to the increased traffic volume, especially in urban areas, cars have become the dominant source of atmospheric pollution. Actions taken to limit the pollution have not been able to counteract the polluting effect of this increase in cars. Limited petroleum resources have initiated the search for alternative fuels for vehicles. These alternatives, except for hydrogen and electricity, will however only give a limited decrease of pollution and for some components, such as aldehydes, the pollution will increase.

Electric vehicles are attractive from both energy and environmental points of view and substantial development programmes are devoted to high energy density batteries which are expected to increase the range and market for this alternative.

The scope of this paper is to compare the overall atmospheric pollution for electric vehicles with the corresponding figures for internal combustion engined (ICE) vehicles using either gasoline or such alternatives as methanol and liquid petroleum gas.

It is shown that the total atmospheric emission for electric vehicles, including what is produced from the power plant, would on a per mile basis be 20% of the comparative figure for an ICE vehicle meeting Californian legislation, which is among the most stringent in the world. For ground emission, which is the most important parameter regarding influence on man and environment the corresponding figure will be substantially lower. Also, the noise level for electric vehicles is radically lower than for cars with internal combustion engines.     

Modeling the effects of congestion on fuel economy for advanced power train vehicles

Fuel-speed curves (FSC) are used to account for the aggregate effects of congestion on fuel consumption in transportation scenario analysis. This paper presents plausible FSC for conventional internal combustion engine (ICE) vehicles and for advanced vehicles such as hybrid electric vehicles, fully electric vehicles (EVs), and fuel cell vehicles (FCVs) using a fuel consumption model with transient driving schedules and a set of 145 hypothetical vehicles. The FSC shapes show that advanced power train vehicles are expected to maintain fuel economy (FE) in congestion better than ICE vehicles, and FE can even improve for EV and FCV in freeway congestion. In order to implement these FSC for long-range scenario modeling, a bounded approach is presented which uses a single congestion sensitivity parameter. The results in this paper will assist analysis of the roles that vehicle technology and congestion mitigation can play in reducing fuel consumption and greenhouse gas emissions from motor vehicles.     

Predicting market potential and environmental benefits of deploying electric taxis in Nanjing,China

This paper investigates the market potential and environmental benefits of replacing internal combustion engine (ICE) vehicles with battery electric vehicles (BEVs) in the taxi fleet in Nanjing, China. Vehicle trajectory data collected by onboard global positioning system (GPS) units are used to study the travel patterns of taxis. The impacts of charger power, charging infrastructure coverage, and taxi apps on the feasibility of electric taxis are quantified, considering taxi drivers’ recharging behavior and operating activities. It is found that (1) depending on the charger power and coverage, 19% (with AC Level 2 chargers and 20% charger network coverage) to 56% (with DC chargers and 100% charger network coverage) of the ICE vehicles can be replaced by electric taxis without driving pattern changes; (2) by using taxi apps to find nearby passengers and charging stations, drivers could utilize the empty cruising time to charge the battery, which may increase the acceptance of BEVs by up to 82.6% compared to the scenario without taxi apps; and (3) tailpipe emissions in urban areas could be significantly reduced with taxi electrification: a mixed taxi fleet with 46% compressed-natural-gas-powered (CNG) and 54% electricity-powered vehicles can reduce the tailpipe emissions by 48% in comparison with the fleet of 100% CNG taxis.     

双层隧道展线的特点分析

上中路隧道、军工路隧道作为上海市城市中环线建设中两个重要的穿越黄浦江节点工程,均采用双管双层隧道方案。结合两个工程的设计,介绍了隧道出盾构工作井后两种不同的平面展线形式,同时分析了"燕尾型"展线与"鱼叉型"展线在各个方面的优缺点。     

客运专线长轨精调经验与体会

我国客运专线建设进入了一个新的时期,高速、平顺的无砟轨道是发展趋势。其中长轨铺设后的精调工作是保证列车高速运行的最关键工作。文章结合武广客运专线的实际,阐述长轨精调整过程的经验及施工过程中的主要质量控制要点。     

天水市现代有轨电车系统建设可行性分析

现代有轨电车是体现国家公交优先政策的一种新型大运量公共交通方式。文章结合天水市发展实际,从道路状况、沿线用地及客流、交通组织等方面对天水市羲皇大道布设有轨电车线路的可行性进行分析,并且介绍了相关规划方案。     

道路货物网络化运输的服务类别和发展模式

基于我国道路货物运输的发展现状,以探索推行道路货物运输网络化的发展模式为主线,以提高道路货物运输组织效率和行业发展水平为最终目标,阐述道路货物网络化运输的概念及内涵,对网络化运输服务进行了划分,构建了我国推行道路货物网络化运输的两类发展模式,并利用图示和文字结合的方式对其进行了分析评价。     

高速公路客运停靠站的设计研究

文章结合高速公路发展现状,系统地阐述了高速公路上客车停靠站建设的必要性,并根据高速公路的特点,研究了停靠站点的基本类型,分析了停靠站的线形及横断面几何设计方法。     

盾构始发水泥土加固后水平冻结温度实测研究

依托于苏州地铁二号线火车站东风井2#洞门盾构始发水平冻结加固工程,通过实时监测杯型冻土壁温度场,分析了不同阶段的盐水温度规律,以及在不同深度、不同土质和不同冻结区域的土体温度发展特征;并计算了不同土质冻土壁厚度、交圈时间和发展速度.监测结果分析表明,在整个冻结期间,任意时间都是板块体加固区测温孔温度低于圆柱体加固区测温孔温度;同一测温孔中,冻结前期水平入土越深温度越高,冻结后期水平入土越深温度越低;在相同冻结能量和冻结时间内,水泥土加固粉砂土比粉质粘土温度要低;水泥土加固粉质粘土释放潜热的天数是水泥土加固粉砂土的2倍;在冻结效果方面,包括冻土壁交圈时间、冻结壁厚度、冻结壁平均发展速度、冻结壁平均温度,水泥土加固粉砂土比水泥土加固粉质粘土更好.     

从数字看中国铁路隧道的建设

根据收集到的有关中国铁路隧道建设比较全面、可靠的统计资料,按年代和铁路线归纳整理列出的,并用数字来阐述截至2005年末中国铁路隧道建设的基本情况与发展历程；同时对隧道命名与隧道长度计算的统一等问题提出建议。     

An environmental-economic evaluation of hybrid electric vehicles: Toyota's Prius vs. its conventional internal combustion engine Corolla

We compare the second generation of the first commercial hybrid electric vehicle (HEV), the Toyota Prius, to the conventional internal combustion engine (ICE) Toyota Corolla. The more complicated and expensive Prius has lower pollutant and carbon dioxide emissions and better fuel economy than the Corolla. In a world of limited resources and many petroleum users and emissions sources, the policy question is whether the best use of resources is to build hybrids, to improve the fuel economy and environmental emissions of other mobile sources, or to devote the resources to other environmental projects. We find that the Prius is not cost-effective in improving fuel economy or lowering emissions. For the Prius to be attractive to US consumers, the price of gasoline would have to be more than three times greater than at present. To be attractive to regulators, the social value of abating tailpipe emissions would have to be 14 times greater than conventional values. Alternatively, the value of abating greenhouse gas emissions would have to be at least $217/t. There are many opportunities for abating pollutant and greenhouse gas emissions at lower cost. We conclude that hybrids will not have significant sales unless fuel prices rise several-fold or unless regulators mandate them.     

Development of a transit network from a street map database with spatial analysis and dynamic segmentation

This paper presents an integrated transit-oriented travel demand modeling procedure within the framework of geographic information systems (GIS). Focusing on transit network development, this paper presents both the procedure and algorithm for automatically generating both link and line data for transit demand modeling from the conventional street network data using spatial analysis and dynamic segmentation. For this purpose, transit stop digitizing, topology and route system building, and the conversion of route and stop data into link and line data sets are performed. Using spatial analysis, such as the functionality to search arcs nearest from a given node, the nearest stops are identified along the associated links of the transit line, while the topological relation between links and line data sets can also be computed using dynamic segmentation. The advantage of this approach is that street map databases represented by a centerline can be directly used along with the existing legacy urban transportation planning systems (UTPS) type travel modeling packages and existing GIS without incurring the additional cost of purchasing a full-blown transportation GIS package. A small test network is adopted to demonstrate the process and the results. The authors anticipate that the procedure set forth in this paper will be useful to many cities and regional transit agencies in their transit demand modeling process within the integrated GIS-based computing environment.     

蒙内铁路长大下坡道制动试验及计算分析

蒙内铁路作为连接东非第一大港蒙巴萨和肯尼亚首都内罗毕的一条客货并行一级线路,对肯尼亚国内以及东非地区的经济发展和政治稳定具有重要的意义,也对于我国"一带一路"战略的实施以巩固中-肯关系和中非关系有着至关重要的意义.由于较为特殊的地理原因使得蒙内铁路全线长大坡道占比超过50％,使得长大坡道上的行车安全成为蒙内铁路安全运营的重中之重.本文以11.7‰的长大下坡道为研究对象,介绍了以DF11机车牵引,17辆编组时以118km/h进行紧急制动试验的情况,制动距离为890m;紧急制动前有充足的充风时间,制动实施至列车管压减为0用时3s,符合规定要求.基于试验结果验证了理论计算和软件计算的可靠性和准确性,计算结果指出为了使17辆编组列车在800m制动距离以内完成制动,当坡度为12‰时,建议其制动速度不高于112km/h,坡度6‰以下时,建议其制动速度不高于118km/h.本文的分析和计算结果旨在为蒙内铁路长大下坡道的安全行车运营以及整体安全控制体系的制定提供有效可靠的试验依据和理论支撑.     

公交查询系统设计与开发

为提供快速简便的城市公交站点、线路查询服务,文章采用B/S模式、ASP.NET（C#）开发环境及工具、Web发布服务方式以及Microsoft SQL Server后台数据库,构建了一个简单、实用的公交查询系统,并对该系统的整体架构、数据库设计及应用程序设计方法进行了介绍。     

土石路堤填筑应力形变场的特征规律研究

在山区高速公路建设中,路堤多采用土石混合料填筑。文章结合西部某高速公路工程项目,对其红色碎屑岩类无粘性土石混填路堤进行数值模拟,着重研究了该类路堤按实际分层厚度30cm填筑过程中的应力形变场的特征及其变化规律及其工程适用性。结果表明,路堤内的最大沉降发生在路堤填筑高度略低于1／2路堤中心线附近的位置,最大主压应力与最小主压应力均表现出随着填筑体厚度的增加而逐渐增大的趋势,在路堤中心线处底部压应力最大,同时在填筑过程中路堤坡面可能发生小范围的拉应力区。     

Evaluation of transit proximity effects on residential land prices: an empirical study in Austin,Texas

The Austin MetroRail line in Texas, U.S.A. began operations in 2010 and since then transit-oriented development projects have been fuelled around train stations. Traditional location theory holds that proximity to a transit station should be capitalized into land prices, and numerous empirical studies have demonstrated the effects with mixed results. However, to date no empirical study has investigated this relationship between the newly built rail line and land prices in Austin. This study fills the research gap and suggests a positive effect associated with transit proximity by employing spatial hedonic models. This study also contributes to the existing literature especially in the context of Texas cities where there is a lack of relevant research on transit-capitalization-related topics, and provides insights for decision-makers with different perspectives regarding further rail investment or transportation financing strategies such as value capture programs.     

高压直流接地极对埋地管道的干扰与防护

文中对直流杂散电流对埋地管道的干扰机理、检测方法、研究现状以及主要防护措施等进行了总结,对研究中存在的问题进行了分析,并针对问题提出了完善高压直流干扰评价标准、研究高压直流干扰机理和开发高压直流干扰区管道防护方法等相关防护建议,对防止直流杂散电流对埋地管道的干扰破坏具有参考意义。     

油气管道音波泄漏检测技术

随着国内石油天然气管道的迅速发展,泄漏检测作为保障管道运行安全的重要手段被深入研究。简要概述了油气管道泄漏检测技术,详细阐述了音波泄漏检测与定位的基本原理、系统的硬件设置及特点,说明了系统实现中存在的问题,并提出了建议。