考虑环境因素的公交车队管理研究

提出了一种公交车辆管理模型,可以在考虑环境因素以及资金、技术等限制条件下做出车辆购买、淘汰的决策.在满足污染物排放限定条件下达到成本投入最小.通过案例分析,结果表明该模型行之有效.     

桥梁加固中粘贴碳纤维布的应用实例

在桥梁的梁板受拉区粘贴碳纤维布能显著提高结构的承栽能力,限制裂缝的发展,提高桥梁的耐久性。以石安高速公路邯郸北互通匝道桥的加固为实例,阐述粘贴碳纤维布在桥梁加固中的应用,具有一定的实用价值。     

预应力钢板箍与CFRP复合加固RC墩柱轴压性能试验研究

提出一种新型的采用预应力钢板箍(PSJ)和碳纤维布(CFRP)复合加固钢筋混凝土(RC)墩柱加固方法(简称PSJ-CFRP)。为验证该新型加固技术的可行性和有效性,进行了8个足尺圆形墩柱轴压性能试验,研究参数包括不同加固方法(PSJ、CFRP和PSJ-CFRP)、钢板箍预应力水平、PSJ与CFRP加固配箍特征值等,比较分析采用不同加固方式加固试件的加固效果、破坏形态和承载力等,研究了PSJ-CFRP复合加固RC墩柱的受压机理,钢板箍预应力度、PSJ与CFRP加固配箍特征值等关键参数对试件轴压性能的影响和规律。试验结果验证了PSJ-CFRP复合加固技术的有效性,CFRP与钢板箍协同工作、优势互补,既提高了试件的承载能力,又改善了试件的变形性能,加固试件呈现延性破坏特征。采用CFRP加固的试件,试件的承载能力得到提高,但变形能力降低,呈现脆性的破坏特征。在相同加固配箍特征值下,减小加固箍板净间距能取得更好的加固效果。在试验和理论分析的基础上,提出了PSJ-CFRP复合加固RC墩柱轴向受压承载力计算公式,能较好地预测加固墩柱的轴心受压承载力。     

An evaluation framework for traffic calming measures in residential areas

The paper evaluates the effectiveness of various traffic calming measures from the perspectives of traffic performance and safety, and environmental and public health impacts. The proposed framework was applied to four calming measures – two types of speed humps, speed tables, and chicanes – to demonstrate its usefulness and applicability. A field experiment using probe vehicles equipped with global positioning system devices was conducted to obtain vehicle trajectory data for use in more realistic simulations. In addition, a recently developed vehicle emissions model was used for more accurate evaluation of environmental and public health impacts. The results show that chicane is better than the other types of traffic calming measures considered, except in terms of vehicle emissions.     

Strategies to achieve deep reductions in metropolitan transportation GHG emissions: the case of Philadelphia

ABSTRACT

This paper investigates strategies that could achieve an 80% reduction in transportation emissions from current levels by 2050 in the City of Philadelphia. The baseline daily lifecycle emissions generated by road transportation in the Greater Philadelphia Region in 2012 were quantified using trip information from the 2012 Household Travel Survey (HTS). Emissions were projected to the year 2050 accounting for population growth and trends in vehicle technology for both the Greater Philadelphia Region and the City of Philadelphia. The impacts of vehicle technology and shifts in travel modes on greenhouse gas (GHG) emissions in 2050 were quantified using a scenario approach. The analysis of 12 different scenarios suggests that 80% reduction in emissions is technically feasible through a combination of active transportation, cleaner fuels for public transit vehicles, and a significant market penetration of battery-electric vehicles. The additional electricity demand associated with greater use of electric vehicles could amount to 10.8 TWh/year. The use of plug-in hybrid electric vehicles (PHEV) shows promising results due to high reductions in GHG emissions at a potentially manageable cost.     

炭纤维复合叠层铝板的制备工艺和实验研究

综合评论了从ＡＲＡＬＬ发展到新一代复合叠层铝合金板的进展。实验研究了新一代的叠层铝板－－炭纤维复合叠层铝板的制备工艺，并提供了所制备的炭纤维复合叠层铝板的性能。结果表明：这种铝板具有ＡＲＡＬＬ板的各种优点，能改进ＡＲＡＬＬ的一些缺点，它的各种性能指标皆优于铝合金板，因此可望取代高强度铝合金板而广泛应用于各类工程项目之中。     

Modeling the relationships among urban passenger travel carbon dioxide emissions,transportation demand and supply,population density,and proxy policy variables

To support the development of policies that reduce greenhouse gas (GHG) emissions by encouraging reduced travel and increased use of efficient transportation modes, it is necessary to better understand the explanatory effects that transportation, population density, and policy variables have on passenger travel related CO₂ emissions. This study presents the development of a model of CO₂ emissions per capita as a function of various explanatory variables using data on 146 urbanized areas in the United States. The model takes into account selectivity bias resulting from the fact that adopting policies aimed at reducing emissions in an urbanized area may be partly driven by the presence of environmental concerns in that area. The results indicate that population density, transit share, freeway lane-miles per capita, private vehicle occupancy, and average travel time have a statistically significant explanatory effect on passenger travel related CO₂ emissions. In addition, the presence of automobile emissions inspection programs, which serves as a proxy indicator of other policies addressing environmental concerns and which could influence travelers in making environmentally favorable travel choices, markedly changes the manner in which transportation variables explain CO₂ emission levels.     

Commuters’ behavior towards upgraded bus services in Greater Beirut: Implications for greenhouse gas emissions,social welfare and transport policy

Climate change is one of the most critical environmental challenges faced in the world today. The transportation sector alone contributes to 22% of carbon emissions, of which 80% are contributed by road transportation. In this paper we investigate the potential private car greenhouse gas (GHG) emissions reduction and social welfare gains resulting from upgrading the bus service in the Greater Beirut Area. To this end, a stated preference (SP) survey on mode switching from private car to bus was conducted in this area and analyzed by means of a mixed logit model. We then used the model outputs to simulate aggregate switching behavior in the study area and the attendant welfare and environmental gains and private car GHG emissions reductions under various alternative scenarios of bus service upgrade. We recommend a bundle of realistic bus service improvements in the short term that will result in a reasonable shift to buses and measurable reduction in private car emissions. We argue that such improvements will need to be comprehensive in scope and include both improvements in bus level of service attributes (access/egress time, headway, in-vehicle travel time, and number of transfers) and the provision of amenities, including air-conditioning and Wi-Fi. Moreover, such a service needs to be cheaply priced to achieve reasonably high levels of switching behavior. With a comprehensively overhauled bus service, one would expect that bus ridership would increase for commuting purposes at first, and once the habit for it is formed, for travel purposes other than commuting, hence dramatically broadening the scope of private car GHG emissions reduction. This said, this study demonstrates the limits of focused sectorial policies in targeting and reducing private car GHG emissions, and highlights the need for combining behavioral interventions with other measures, most notably technological innovations, in order for the contribution of this sector to GHG emissions mitigation to be sizable.     

高速铁路生命周期碳排放计算方法

基于生命周期评价理论,对高速铁路生命周期二氧化碳排放计算的边界进行界定,将高速铁路的生命周期划分为基础设施建造、运营和回收3个阶段；根据对各阶段高速铁路二氧化碳排放清单的分析,分别给出各个阶段二氧化碳排放的计算式；通过算例分析了高速铁路在建造和运营阶段碳排放的特点.分析和数值计算结果表明,虽然在高速铁路基础设施建设过程中由于大量建设材料和高能耗施工机械的使用,使得高速铁路建造阶段的二氧化碳排放量相对较多；但是,由于高速铁路具有节约能源、节省土地和货运增量替代效应等特点,使得高速铁路进入运营阶段后二氧化碳的排放量大幅度减少,即从生命周期全过程来看,高速铁路具有较好的减排效果.     

混合不确定条件下绿色多式联运路径优化

主要研究了当运输时间、中转时间、客户需求和中转集拼货运量四重混合不确定因素服从随机分布时的绿色多式联运路径优化问题，运用随机优化理论，以运输成本、碳排放成本和时间惩罚成本为目标，建立混合不确定条件下绿色多式联运路径优化模型.通过对各子目标函数权重进行赋值，得出考虑不同成本因素的多式联运路径优化方案.探讨时间、需求和网络服务能力对多式联运路径优化结果的灵敏度分析，发现各成本随时间变动而变化的规律和边际运输成本最小时的服务时间；当货运量形成规模效应后可降低边际运输成本；不同网络服务规模的运输路径优化结果，以及满足客户不确定需求的最小网络配置.