The effect of non-recreational transport cycling on use of other transport modes: A cross-sectional on-line survey

Accurate modelling of the health and environmental benefits of non-recreational transport cycling requires information about its effects on the use of other transport modes. Relevant research has not focussed on cycling for transport in a general context (as opposed to bikeshare), nor allowed for multi-modal trips. The influence of trip- and personal-characteristics on whether cycling replaces car-driving have yet to be considered. The present study aimed to address these research gaps. An on-line cross-sectional survey was completed by 1525 Australians who cycle for transport at least once per week. For the most recent trip completed (at least partly) by bicycle participants provided trip distance, and percentage travelled by car, public transport (PT), and walking. They also provided the percentage travelled by each mode for the same trip before taking up transport cycling; and a hypothetical future trip when riding is not possible. Compared to the same trip before, fifty percent of recent trips reduced car use, and around 1/3 eliminated a 100%-car trip. Reduced car use was significantly less likely for trips under 7.5 km, commuting, females, respondents under 55, and regular cyclists. Reduced car use was less likely for respondents who started riding because it is flexible, and more likely for those who started riding to avoid parking. Car-use was reduced by an average of 6.2 km per trip, and each bicycle-km cycled replaced 0.5 car-km. Participants report that since taking up cycling, even when they cannot use their bike, they use cars less and use PT more compared to before they took up cycling. Results suggest that previous studies underestimated the extent to which transport cycling replaces car travel, and highlights trip types and population groups to target with cycling promotion strategies. Information about the per-trip and per-bicycle-km replacement of car, PT and walking may be used for more accurate estimation of the benefits of transport cycling than has hitherto been possible.     

Low carbon maritime transport: How speed,size and slenderness amounts to substantial capital energy substitution

Three responses that reduce energy consumption and CO₂ emissions in maritime transport are slower speeds, larger vessels and slender hull designs. We use crude oil carriers as our illustrative example; these represent nearly a quarter of international sea cargo movements. We estimate the potential and costs in these which can all be described as capital substituting for energy and emissions. At different degrees of flexibility and time scales: speed reductions are feasible immediately when there are vessels available, though more capital will be tied up in cargo. Deployment of larger and more slender vessels to a greater extent requires fleet renovation, and also investments in ports and infrastructure. A novel finding in our analysis is that if bunker costs rise as a result of emission costs (fees, quotas), then this may depress speeds and emissions more than if they result from higher oil prices. The reason is that for higher oil prices, more capital tied up in cargo may give cargo owners an interest in speeding up, partly counteracting the impulse from fuel costs that tends to slow vessels down. Emission costs, in contrast, do not raise cargo values.     

铁路网重空车流径路整体优化模型

基于我国铁路车流径路呈树形结构的特点,将分车种的空车调配纳入车流径路的优化体系,同时在满足点线能力限制的前提下,以重空车流整体走行费用最小为目标,构建了车流运行径路的优化模型,并在此基础上,考虑到空车调配过程中的车种代用因素,对模型进行扩展,描述了铁路网重空车流的分配方案．最后,以我国东北部分区域路网为案例背景,通过优化求解,获得了满意的车流径路方案和空车调配轮廓方案,从而验证了模型的合理性和有效性．     

英汉说明文体中省略与替代之比较

省略和替代是语法篇章结构中衔接语篇的两种常用的连句方式。本文以12段英汉说明文段落为语料着重分析了省略和替代在篇章衔接中的使用频率和表现差异。     

Forecasting telecommuting

Transportation planners increasingly recognize telecommuting as an important trend. But while they often advocate telecommuting as a transportation demand management strategy, transportation planners have made little progress toward incorporating telecommuting into transportation forecasts, at least partly because of the limited data available. In this paper we explore four alternative methodologies for forecasting telecommuting and discuss the kinds of data that must be collected before these methodologies can be applied. The first approach is trend extrapolation, using curves of technological substitution. Sufficient data are currently available to produce forecasts, albeit highly uncertain forecasts, using this approach. However, even with better data this approach does not address underlying factors and trends that will affect the future of telecommuting. As a result, we explore three additional approaches that should produce more reliable forecasts but which require new data and knowledge about telecommuting: analyzing the characteristics of telecommuters in contrast to nontelecommuters, analyzing factors affecting the individual choice to telecommute, and incorporating telecommuting into traditional transportation forecasting models.     

MARINFLOC舱底污水处理系统性能分析

油水分离器处理船舶舱底含油污水存在缺陷，Marinfloc Bilge Water Cleaning System可以解决这一问题。本文分析了Marinfloe Bilge Water Cleaning System处理含油舱底污水的机理，介绍了系统的构成和工作性能，对日常维护保养和常见故障排除提出了解决的措施。并预言这种系统将会取代现有的油水分离器。     

物流业发展要素的替代弹性

为提升物流产业发展要素的替代组合效能,从技术进步偏向性视角入手,研究了物流产业劳动力要素与资本要素间的要素替代弹性。基于可变替代弹性（Variable Elasticity of Substitution, VES）生产函数的要素替代演变模型,识别出物流发展要素的替代弹性和发展过程中的偏向性和替代组合效应。结果表明,物流业的要素替代弹性与本行业增长率呈显著正相关性,资本要素对劳动力要素具有较强的替代性;替代弹性能反映出劳动力价格要素的偏态特征;资本优势推动着物流产业的不断更迭进步,有助于提高物流资源的整合;资本要素、劳动力要素和科学技术要素限制了物流业的创新发展效能;物流产业发展要素替代性促进了物流业专业化进程;资本要素对物流业的发展推动作用较大。研究认为,把握资本要素的替代弹性效应,是形成物流贸易市场高质量发展的关键所在。     

Measuring the performance of airport resilience to severe weather events

The increased severe weather events in recent years as a result of global climate change has created a substantial challenge for aviation system operation. Although transportation engineers and planners have attempted to improve system resilience through the adaptation of new technologies and the implementation of various strategies to achieve effective risk management, it remains unclear how resilience performance (measured by the speed of recovery) of airports varies in different severe weather events and what factors may explain such variations. This paper addresses these fundamental questions using the aviation system in China as an example. A resilience metric, which reflects the speed of recovery (bounce back) from a shock, was developed to measure the performance of airport resilience under various severe weather conditions. In addition, an empirical econometric analysis was conducted based on a dataset that includes both detailed aviation performance and weather conditions for the period of October 2016 – September 2017. The research findings show that airport resilience to severe weather events does vary substantially based on factors, such as weather conditions, airport capacity, and the level of modal substitution. In particular, the recovery time of air services in central and south China tends to be relatively longer in thunderstorms than other weather conditions. The study also confirms that modal substitution is a very effective resilience tactic of the transportation system as the recovery speed of air service was found to be faster by 22.9% if an alternative mode, such as high-speed rail (HSR) service was also available in the city.     

柴油-天然气双燃料发动机的性能研究

在高压共轨电控柴油发动机的基础上,研发了柴油-天然气双燃料发动机。该发动机在原机电控系统保持不变的情况下,增加了一套双燃料电控系统,使其可以在纯柴油和柴油天然气双燃料两种模式下工作。在柴油天然气双燃料模式下,以少量的柴油引燃适量的天然气进行混合燃烧,达到与原机相同的功率及扭矩输出,天然气对柴油的平均替代率达85%以上,提高了该发动机的经济性。     

Discretionary activity time allocation of individuals between in-home and out-of-home and between weekdays and weekends

This paper formulates a model for the allocation of total weekly discretionary time of individuals between in-home and out- of-home locations and between weekdays and the weekend. The model formulation takes the form of a continuous utility-maximizing resource allocation problem. The formulation is applied to an empirical analysis using data drawn from a 1985 time-use survey conducted in the Netherlands. This survey gathered time-use information from individuals over a period of one week and also collected detailed household-personal socio-demographic data. The empirical analysis uses household socio-demographics, individual socio-demographics, and work-related characteristics as the explanatory variables. Among the explanatory variables, age of the individual and work duration during the weekdays appear to be the most important determinants of discretionary time allocation.