Influence of driving patterns on vehicle emissions: A case study for Latin American cities

On-board real-time emission experiments were conducted on 78 light-duty vehicles in Bogota. Direct emissions of carbon monoxide (CO), carbon dioxide (CO₂), nitrogen oxides (NO_x) and hydrocarbons (HC) were measured. The relationship between such emissions and vehicle specific power (VSP) was established. The experimental matrix included both gasoline-powered and retrofit dual fuel (gasoline–natural gas) vehicles. The results confirm that VSP is an appropriate metric to obtain correlations between driving patterns and air pollutant emissions. Ninety-five percent of the time vehicles in Bogota operate in a VSP between −15.2 and 17.7 kW ton⁻¹, and 50% of the time they operate between −2.9 and 1.2 kW ton⁻¹, representing low engine-load and near-idling conditions, respectively. When engines are subjected to higher loads, pollutant emissions increase significantly. This demonstrates the relevance of reviewing smog check programs and command-and-control measures in Latin America, which are widely based on static (i.e., idling) emissions testing. The effect of different driving patterns on the city’s emissions inventory was determined using VSP and numerical simulations. For example, improving vehicle flow and reducing sudden and frequent accelerations could curb annual emissions in Bogota by up to 12% for CO₂, 13% for CO and HC, and 24% for NO_x. This also represents possible fuel consumption savings of between 35 and 85 million gallons per year and total potential economic benefits of up to 1400 million dollars per year.     

The role of the air transport service in interregional long-distance students’ mobility in Italy

This study investigates the role of air transport service in the attractiveness of universities to national students, examining how it might stimulate local economic development by attracting highly skilled labor. Examining the flow of Italian university students at the provincial level in 2003–2012, we find that the air transport service affects university attractiveness for long-distance students living at least 300 km from their university. Specifically, accessibility increases with the proximity of universities to airports, when low-cost carriers serve university routes and more alternative airports exist at the origin. Further, our results suggest that, over the last decade, air transport service has facilitated mobility of long-distance students from southern areas to universities in the north of Italy, where students generally move to increase their future prospects.     

交通经济带CA模拟研究

交通经济带(Traffic Economic Belt,简称TEB)是描绘区域经济组织形式的经济学概念,它将区域经济框架构成方式应用辐带状空间地域信息表述出来。本文在统计力学中的元胞自动机原理(Cellular Automata,简称CA)基础上,对交通经济带进行了模拟和探讨。     

交通条件对经济区位的影响——以苏通大桥的建成为例

文章以苏通大桥建成为例,介绍了南通在大桥建成前的经济区位条件,分析了大桥建成后对南通经济区位的改变及其对南通发展的影响,指出了交通条件对促进区域经济的发展具有重要的作用。     

公路科技成果直接经济效益分析方法探讨

本文以工厂热再生技术、半柔性基层两项科技成果直接经济效益计算为例,认真分析总结了公路科技成果直接经济效益计算原则及分析方法,将直接经济效益分类进行计算,为今后公路科技成果直接经济效益分析计算,提供有价值的参考。     

TransMilenio BRT system in Bogota,high performance and positive impact – Main results of an ex-post evaluation

The paper presents the main characteristics, costs and impacts of TransMilenio, the bus based mass transit system of Bogotá, using BRT corridors and feeder services. An ex-post cost-benefit analysis is done, including monetary valuation of direct impacts on travel time and travel cost and externalities, such as improved road safety and air quality. Impacts on crime, land values, employment and tax revenue are also presented. The results are positive and robust; nevertheless, it is important to recognize that user perception has declined and there is urgent need to introduce service improvements. The paper also includes an ex-ante evaluation of the projected expansion using current costs, which indicates the need to limit construction capital costs. The results are an indication of the potential of BRT, and the evaluation methodology is applicable to other transit projects.     

既有桥梁改造方案经济分析模型的构建

在确定既有桥梁各种改造方案的基础上,从工程经济的原理出发,在桥梁全寿命期内,考虑所有可能发生的费用,建立桥梁的全寿命周期费用模型(平均年费用模型),并且对加固、重建方案的平均年费用进行相互比较、分析。同时还基于平均年费用的分析模式,对桥梁的经济使用寿命进行了预测。     

技术指标在设计中的灵活运用

讨论了道路设计中诸多制约因素的互相影响,通过分析,预测道路的近、远期交通量以及在区域控制网中的地位,合理确定道路的线形技术指标和经济指标,并阐述了这些指标在设计中的灵活运用。     

论财务管理在医疗机构发展中的作用

随着国家医疗卫生改革的不断深入,医院要想在激烈的市场竞争中立于不败之地,医院必须加强财务管理工作。笔者从发挥财务监督职能、财务工作透明化,确定财务管理目标、合理编制财务预算,建立健全财务制度内部控制制度,实行成本核算,搞好医院财务活动的分析和评价五个方面进行了论述,有利于提高医院财务管理水平,使医院在错综复杂的市场竞争环境中立于不败之地。     

旧水泥砼路面加铺沥青面层结构技术经济分析

文章结合某高速公路水泥混凝土路面大修情况,介绍不同路段采用不同的加铺沥青层设计方案,并就路面维修建设费用和使用寿命间的经济关系进行分析和研究,为同类维修项目提供参考。