收费公路计重定价理论模型

为了遏制超限运输,解决公路通行费征收中的不公平问题,必须改变目前按车型收费的计费模式,实施计重收费。建立计重收费的定价理论模型是推动这种收费方式健康发展的关键。在提出计重收费定义和类型的基础上,根据公路的准公共产品特性,分析了各种价格结构管制定价模式的特点,提出公路收费宜采用非线性的"两部定价"理论模型。结合收费公路费用分摊的具体方法,给出了收费公路计重定价理论模型,并对相关参数进行了标定。该模型已在江苏省和青海省计重收费标准制定中使用。     

Performance Evaluation of Hybrid-Drive Buses and Potential Fuel Savings in Brazilian Urban Transit

Transporting more than 55 million passengers per day, buses are the main transit mode in Brazil. Most of these vehicles use diesel oil and this situation causes dependence on oil, extensive greenhouse gas emissions and increasing air pollution in urban areas. In order to improve this situation the options for Brazilian cities include the use of alternative fuels and new propulsion technologies, such as hybrid vehicles. This article proposes a procedure for evaluating the performance of a recently developed Brazilian hybrid-drive technology. A simple procedure is presented to compare hybrid-drive buses with conventional diesel buses in urban operation focusing on fuel economy and the potential for reducing diesel oil consumption through the use of hybrid-drive buses. Field tests carried out by the authors indicate that fuel consumption improvement through the use of hybrid-drive buses would certainly exceed 20%, resulting in lower fuel costs and reduced carbon dioxide (CO₂) emissions.     

治理公路超载超限运输的长效机制和对策研究

为建立治理超载超限运输的长效机制,首先建立了运输企业收入的计量模型,分析了企业利润与运输价格、运输成本、超载罚款等变量之间的互动关系及企业获得最大利润的条件。在此基础上,针对中国道路货运市场结构的特点,从理性经济人的角度,对运输企业在“惩罚博弈”下可能的行为选择进行了研究;其次结合美国治理超载超限运输的经验,分析了不同执法强度和执法密度组合的执法策略及其适用条件、执法效果等,对中国治理超载超限运输提出了解决方案和具体的政策建议,对中国治理超载超限运输具有指导意义。     

Connectivity analysis of the global shipping network by eigenvalue decomposition

ABSTRACT

Maritime shipping necessitates flexible and cost-effective port access worldwide through the global shipping network. This paper presents an efficient method to identify major port communities, and analyses the network connectivity of the global shipping network based on community structure. The global shipping network is represented by a signless Laplacian matrix which can be decomposed to generate its eigenvectors and corresponding eigenvalues. The largest gaps between the eigenvalues were then used to determine the optimal number of communities within the network. The eigenvalue decomposition method offers the advantage of detecting port communities without relying on a priori assumption about the number of communities and the size of each community. By applying this method to a dataset collected from seven world leading liner shipping companies, we found that the ports are clustered into three communities in the global container shipping network, which is consistent with the major container trade routes. The sparse linkages between port communities indicate where access is relatively poor.     

Customizing driving cycles to support vehicle purchase and use decisions: Fuel economy estimation for alternative fuel vehicle users

Wider deployment of alternative fuel vehicles (AFVs) can help with increasing energy security and transitioning to clean vehicles. Ideally, adopters of AFVs are able to maintain the same level of mobility as users of conventional vehicles while reducing energy use and emissions. Greater knowledge of AFV benefits can support consumers’ vehicle purchase and use choices. The Environmental Protection Agency’s fuel economy ratings are a key source of potential benefits of using AFVs. However, the ratings are based on pre-designed and fixed driving cycles applied in laboratory conditions, neglecting the attributes of drivers and vehicle types. While the EPA ratings using pre-designed and fixed driving cycles may be unbiased they are not necessarily precise, owning to large variations in real-life driving. Thus, to better predict fuel economy for individual consumers targeting specific types of vehicles, it is important to find driving cycles that can better represent consumers’ real-world driving practices instead of using pre-designed standard driving cycles. This paper presents a methodology for customizing driving cycles to provide convincing fuel economy predictions that are based on drivers’ characteristics and contemporary real-world driving, along with validation efforts. The methodology takes into account current micro-driving practices in terms of maintaining speed, acceleration, braking, idling, etc., on trips. Specifically, using a large-scale driving data collected by in-vehicle Global Positioning System as part of a travel survey, a micro-trips (building block) library for California drivers is created using 54 million seconds of vehicle trajectories on more than 60,000 trips, made by 3000 drivers. To generate customized driving cycles, a new tool, known as Case Based System for Driving Cycle Design, is developed. These customized cycles can predict fuel economy more precisely for conventional vehicles vis-à-vis AFVs. This is based on a consumer’s similarity in terms of their own and geographical characteristics, with a sample of micro-trips from the case library. The AFV driving cycles, created from real-world driving data, show significant differences from conventional driving cycles currently in use. This further highlights the need to enhance current fuel economy estimations by using customized driving cycles, helping consumers make more informed vehicle purchase and use decisions.     

基于需求弹性的城市公交票价优化方法及实证分析

城市公交票价是公交系统健康发展的重要因素，票价制定需兼顾公交企业的市场性和公益性双重属性，在保证服务质量的同时，考虑运营成本和最大限度吸引公交需求，实现经济效益和社会效益的双赢.在本文中，根据用户均衡理论，构建了城市多方式交通出行的需求分析模型，采用灵敏度分析方法给出了城市公交价格-需求弹性的计算方法.在此基础上，充分考虑了各种方式的交通特征、公交需求弹性、公交运营成本及政府限价等因素，提出了城市公交票价优化的数学规划模型，并给出了求解算法.最后，以国内某城市居民出行调查及公交运营数据为基础，分析了不同条件下公交客运需求的变化规律及城市公交票价的优化策略.     

Career development for women in maritime industry: organisation and socialisation perspectives

For centuries, the maritime industry has been a recognised place in society dominated solely by men, and even though there were women involved, they were mostly on the periphery. This research aims to fill the gap of women’s career development in this field, by investigating the relationships among the degree of organisational socialisation, women’s workplace culture, and the career development of women in the maritime workplace. The analyses are conducted with the structural equation model with 202 valid questionnaires. The results indicated that women’s workplace culture has a significantly negative relationship with the degree of organisational socialisation, and then in turn, it has a significantly positive relationship with women’s career development in the maritime industry. Finally, the results also indicate that the mediating effect of organisational socialisation existed between women’s workplace culture and women’s career development. According to the empirical analysis, this study makes conclusions as well as suggestions for the maritime enterprises as the reference for human resource management.     

无人船在港口水域海事监管中的应用探讨

近年来,随着与船舶自主航行相关的信息技术、人工智能技术水平的提高,无人船舶行业取得了长足的发展,其在海上安保、环境监测等领域应用也越来越成熟。为推动无人船在海事管理方面的应用研究,破解港口水域海事监管手段不足的瓶颈问题,文中在分析港口水域海事监管特点和无人船系统建设条件的基础上,定量研究了无人船在港口水域海事监管应用面临的性能指标确定、船型平台选择、载荷设备搭配、运行管理体系建设等方面的具体问题,提出了一种港口水域海事监管无人船系统的应用解决方案。     

基于价值工程的全生命周期趸船材质方案比选研究

将趸船整个生命周期过程中的技术先进性、经济合理性和环境协调性有机地融合为一体,基于价值工程理论提出趸船材质方法比选。实例表明在千岛湖这样的大吨位船舶碰撞概率很小的水域,采用混凝土趸船明显优于钢质趸船。