Smart charging management for shared autonomous electric vehicle fleets: A Puget Sound case study

Increasingly, experts are forecasting the future of transportation to be shared, autonomous and electric. As shared autonomous electric vehicle (SAEV) fleets roll out to the market, the electricity consumed by the fleet will have significant impacts on energy demand and, in turn, drive variation in energy cost and reliability, especially if the charging is unmanaged. This research proposes a smart charging (SC) framework to identify benefits of active SAEV charging management that strategically shifts electricity demand away from high-priced peak hours or towards renewable generation periods. Time of use (TOU), real time pricing (RTP), and solar generation electricity scenarios are tested using an agent-based simulation to study (1) the impact of battery capacity and charging infrastructure type on SAEV fleet performance and operational costs under SC management; (2) the cost reduction potential of SC considering energy price fluctuation, uncertainty, and seasonal variation; (3) the charging infrastructure requirements; and (4) the system efficiency of powering SAEVs with solar generation. A case study from the Puget Sound region demonstrates the proposed SC algorithm using trip patterns from the regional travel demand model and local energy prices. Results suggest that in the absence of electricity price signals, SAEV charging demand is likely to peak the evening, when regional electricity use patterns already indicate high demand. Under SC management, EVs with larger battery sizes are more responsive to low-electricity cost charging opportunities, and have greater potential to reduce total energy related costs (electricity plus charging infrastructure) for a SAEV fleet, especially under RTP structure.     

The impacts of connected vehicle technology on network-wide traffic operation and fuel consumption under various incident scenarios

ABSTRACT

Incidents are a major source of traffic congestion and can lead to long and unpredictable delays, deteriorating traffic operations and adverse environmental impacts. The emergence of connected vehicles and communication technologies has enabled travelers to use real-time traffic information. The ability to exchange traffic information among vehicles has tremendous potential impacts on network performance especially in the case of non-recurrent congestion. To this end, this paper utilizes a microscopic simulation model of traffic in El Paso, Texas to investigate the impacts of incidents on traffic operation and fuel consumption at different market penetration rates (MPR) of connected vehicles. Several scenarios are implemented and tested to determine the impacts of incidents on network performance in an urban area. The scenarios are defined by changing the duration of incidents and the number of lanes closed. This study also shows how communication technology affects network performance in response to congestion. The results of the study demonstrate the potential effectiveness of connected vehicle technology in improving network performance. For an incident with a duration of 900?s and MPR of 80%, total fuel consumption and total travel time decreased by approximately 20%; 26% was observed in network-wide travel time and fuel consumption at 100% MPR.     

高铁动车组司机连续作业时长的研究

本文在分析动车组司机感知、判断、操作特性的基础上,采用实验心理学测试方法采集司机的各项指标,根据试验测试数据,通过贝叶斯统计学的方法确定合理的高铁动车组司机乘务作业时长,建立乘务作业时长与各项测试指标之间的关系模型。通过算例验证,动车组司机安全可靠度测试等级为良好,并提出相应的改进措施     

Willingness-to-pay for alternative fuel vehicle characteristics: A stated choice study for Germany

In the light of European energy efficiency and clean air regulations, as well as an ambitious electric mobility goal of the German government, we examine consumer preferences for alternative fuel vehicles (AFVs) based on a Germany-wide discrete choice experiment among 711 potential car buyers. We estimate consumers’ willingness-to-pay and compensating variation (CV) for improvements in vehicle attributes, also taking taste differences in the population into account by applying a latent class model with 6 distinct consumer segments. Our results indicate that about 1/3 of the consumers are oriented towards at least one AFV option, with almost half of them being AFV-affine, showing a high probability of choosing AFVs despite their current shortcomings. Our results suggest that German car buyers’ willingness-to-pay for improvements of the various vehicle attributes varies considerably across consumer groups and that the vehicle features have to meet some minimum requirements for considering AFVs. The CV values show that decision-makers in the administration and industry should focus on the most promising consumer group of ‘AFV aficionados’ and their needs. It also shows that some vehicle attribute improvements could increase the demand for AFVs cost-effectively, and that consumers would accept surcharges for some vehicle attributes at a level which could enable their private provision and economic operation (e.g. fast-charging infrastructure). Improvement of other attributes will need governmental subsidies to compensate for insufficient consumer valuation (e.g. battery capacity).     

基于耦合度模型的铁路发展需求性分析

目前我国存在地区经济与铁路发展水平不协调,以及不同地区整体发展水平不均衡的情况,在制定铁路发展方针时,应根据各地区铁路发展的需求程度,对有限的新建铁路投资进行合理分配。基于容量耦合理论提出了耦合度模型,得以计算铁路系统与地区经济系统的综合发展水平和耦合协调度,据此确定地区的铁路发展需求度,从而建立一种定量评估各地区对铁路新建里程相对需求量的方法。对"十二五"期间铁路发展规划的分析表明,大部分省份铁路规划新建里程与基于耦合度模型计算的铁路相对需求量基本一致;对一部分欠发达地区,铁路规划新建里程与基于耦合度模型计算的铁路相对需求量差距较大。     

时间维度下上海市共享单车骑行模式研究

基于上海市摩拜单车一个星期的骑行数据，从时间角度深入挖掘骑行数据背后隐藏的行为模式和规律. 统计结果显示，工作日和周末的骑行行为存在显著差异，工作日呈现两个明显骑行高峰时段，周末的骑行分布则比较均匀. 在区分工作日和周末的基础上，根据骑行行为对每日的骑行者进行分类，每组骑行者均表现出独特的骑行开始时间和骑行时长. 基于周中的一天与骑行开始时间，以及周中的一天与骑行时长这两个组合分别计算赫希曼指数 (HHI)，证实共享单车骑行高度的时间规律性；周中的一天与骑行开始时间组合的HHI值具有更大的标准差，显示了共享单车的灵活性. 对共享单车骑行模式的探究，能够在一定程度上促进城市交通系统的持续改善，吸引更多出行者使用绿色交通方式.     

Technical standardization of ITS and Asian initiatives for intelligent mobility

User-centric intelligent mobility businesses emerge and prosper in Asian metropolitan areas by utilizing the progress if information and communication technology (ICT). Under the rise of private lead initiatives on intelligent transport systems (ITS), the roles of public sectors are still large. Public sectors should precisely identify the extensive ITS services by considering the regional conditions and deploy them by collaboration between the public and private. Public sectors also are strongly encouraged to identify the benefits acquired by development and compliance of the international technical standards. Furthermore, in order to maximize the potential capacity of ICT, improvements of social infrastructures are required by the public sectors together with private businesses. With the realization of the collaboration works, Asian regions are well deserved to take the lead in future ITS initiatives.     

Understanding cyclists’ perceptions,keys for a successful bicycle promotion

Many variables that influence bicycle use beyond time and cost have been included in models of various types. However, psycho-social factors that make the bicycle eligible as a modal alternative have not been identified properly. These factors are related to intention, attitudes and perceptions, and their identification can contribute to obtain the keys for a successful bicycle policy. Here, an in-depth investigation of cyclists’ perceptions is attempted using a large university survey designed and collected ad hoc, and then applying exploratory and confirmatory factor analyses. After identifying fourteen factors, a structural equations model was estimated to find structure and relationships among variables and to understand users’ intentions to use the bike. Four (latent) variables are identified, namely convenience, pro-bike, physical determinants and exogenous restrictions. The main conclusion is that convenience (flexible, efficient) and exogenous restrictions (danger, vandalism, facilities) are the most important elements to understand the attitudes towards the bicycle.     

The attraction of countryside sites

The distribution of car trips to countryside sites, though primarily dependent upon accessibility, is also a function of the site attraction. This paper describes an attempt to assess attraction in numerical terms drawing upon techniques used by the geographer and the transportation planner. It is based on a behavioural model in which excursion rates and travel times of visitors to countryside sites were obtained by questionnaire surveys in the West Midlands region.

A method is established for determining sequentially the relative attraction of pairs of sites through plotting excursion rate ratios and the respective travel time ratios for common visitor origins; therefrom, for a travel time ratio of unity, the relative excursion rates can be found. Further investigation suggested that site extensiveness contributes to attraction in proportion to the square root of the area. Relative intrinsic attractiveness—essentially land form and mantle—can be determined using a points scoring system. These two components when combined with the accessibility component enables a site distribution factor to be obtained.

The application of distribution factors is demonstrated in relation to an existing attractor system and one origin zone; the effects of the introdction of a new site into this system is postulated; both cases above having real life parallels. Agreement between observed and synthesized excursion rates was within the range ±10 to 20 percent.     

Missing the tide? Workplace cultural differences as a barrier to seafarer mobility in the U.S. workboat and sail training sectors

ABSTRACT

While previous research details the psychological and social benefits of sail training programs for amateur ‘trainees,’ much less is known about the value and transferability of sail training work experience in terms of professional development for seafaring careers. This article reviews the current state of scientific knowledge on sail training and presents the findings of a qualitative study of maritime recruiter perceptions at 10 U.S. flag workboat companies. Results suggest that the maritime industry may benefit from an improved understanding of the role that sail training programs and the sail training community can play in training and inspiring the next generation of motivated and professional seafarers. Workboat recruiters see positive and negative aspects of sail training experience and perceive cultural divides within the maritime industry that may affect a seafarers’ job mobility, whether or not such divides actually exist.