Impacts of plug-in electric vehicles in the portuguese electrical grid

Powertrain electrification is currently the best alternative to ensure sustainable energy efficient personal mobility, increasing the integration of intermittent Renewable Energy Sources (RES), improving air quality in urban centres, and reducing greenhouse gas emissions from the transport sector and their dependence on fossil energy sources. With the increasing number of Electric Vehicles (EVs) available from automotive manufacturers, one key question that arises is the capability of the electrical grid to feed the increasing energy demand of the EV fleet without major investments. This paper shows that a progressive penetration of EVs, even at a rapid rate, is perfectly possible for vehicles that offer autonomy, energy consumption and charging characteristics that are currently available in the market. This analysis is based on data acquired during a year, using a Plug-in Hybrid Electric Vehicle (PEV) as the only vehicle for a typical, Southern European Portuguese family. The energy consumption of a gasoline and electric vehicle is presented, as well as its impact on the household load pattern. An analysis of the impact on the grid is also presented, considering several penetration rates (100 thousand, 500 thousand and 1 million vehicles). As well as the avoided use of fossil fuel per vehicle and consequent reduction in overall emissions when compared with a conventional vehicle.     

The employee mobility budget: Aligning sustainable transportation with human resource management?

This paper discusses how a particular tool in the employment relationship has become part of a desirable transport future. We examine how and why the employee mobility budget has entered the set of sustainable transport measures in Belgium. In a discourse analysis, we examined 52 articles from newspapers, magazines as well as research reports. The main actors in the debate are identified using an exploratory social network analysis, and we discuss the various definitions of the employee mobility budget, the framing of the problems to be solved (in the first place congestion), and the main conflicts between actors. The results reveal the sustained efforts to put the idea on the agenda and the formation of a coalition of the willing. The fact that the mobility budget concept is highly compatible with the hegemonic discourse on employment relations contributes to its popularity. Finally, the individualisation of employment relations and the decrease in attention for environmental aspects are highlighted as potential threats of the type of sustainable mobility policy studied in this paper.     

Fine-tuning ADAS algorithm parameters for optimizing traffic safety and mobility in connected vehicle environment

Under the Connected Vehicle environment where vehicles and road-side infrastructure can communicate wirelessly, the Advanced Driver Assistance Systems (ADAS) can be adopted as an actuator for achieving traffic safety and mobility optimization at highway facilities. In this regard, the traffic management centers need to identify the optimal ADAS algorithm parameter set that leads to the optimization of the traffic safety and mobility performance, and broadcast the optimal parameter set wirelessly to individual ADAS-equipped vehicles. Once the ADAS-equipped drivers implement the optimal parameter set, they become active agents that work cooperatively to prevent traffic conflicts, and suppress the development of traffic oscillations into heavy traffic jams. Measuring systematic effectiveness of this traffic management requires am analytic capability to capture the quantified impact of the ADAS on individual drivers’ behaviors and the aggregated traffic safety and mobility improvement due to such an impact. To this end, this research proposes a synthetic methodology that incorporates the ADAS-affected driving behavior modeling and state-of-the-art microscopic traffic flow modeling into a virtually simulated environment. Building on such an environment, the optimal ADAS algorithm parameter set is identified through a multi-objective optimization approach that uses the Genetic Algorithm. The developed methodology is tested at a freeway facility under low, medium and high ADAS market penetration rate scenarios. The case study reveals that fine-tuning the ADAS algorithm parameter can significantly improve the throughput and reduce the traffic delay and conflicts at the study site in the medium and high penetration scenarios. In these scenarios, the ADAS algorithm parameter optimization is necessary. Otherwise the ADAS will intensify the behavior heterogeneity among drivers, resulting in little traffic safety improvement and negative mobility impact. In the high penetration rate scenario, the identified optimal ADAS algorithm parameter set can be used to support different control objectives (e.g., safety improvement has priority vs. mobility improvement has priority).     

Observing individual dynamic choices of activity chains from location-based crowdsourced data

The existing efforts on studying human mobility and activity using location-based crowdsourced data mainly focus on obtaining the activity chain pattern in a region at an aggregate level. To observe individual dynamic choices of activity chains, this paper presents a data-driven approach to estimating individual-specific activity chain set and corresponding choice probabilities for a given person over a 24-h period using crowdsourced data from location-based service apps. We detect an individual-specific stochastic activity set using a contextual-parcel data analysis. Based on the time geography theory, we refine a space-time bicone concept to construct an activity-travel space-time-state network from the stochastic activity set. These space-time bicone constraints define a set of potential activity choices to reduce the search space of activity location and duration choices. We construct an activity state transition graph from the space-time-state network and calculate a Markov matrix for activity choice probabilities. Furthermore, we calculate the probabilities of activity chain choices using the Markov matrix. We also visualize individual-specific activity chain set in a space-time-state network to show the dynamic choices of individual daily mobility and activity. We demonstrate the proposed approach through conducting numerical analyses using crowdsourced data from location-based service apps - Foursquare and Twitter to construct individual-specific activity choice sets and corresponding choice probabilities.     

Effects of built environment on walking at the neighbourhood scale. A new role for street networks by modelling their configurational accessibility?

The hypothesis of this paper is that some features of the built environment, particularly those concerned with the accessibility of the street network, could be associated with the proportion of pedestrians on all trips (modal split) found in different parts of a city. Quantitative analysis (bi-variate correlation and a multiple regression model) was used to establish the association between variables. The study area covered a substantial part of the metropolitan area in Madrid, Spain. Results showed a consistent influence of five particular indexes in the multi-variate model. Not surprisingly for this kind of research, four of them described density and mix of land uses. But perhaps more interestingly, the first one was a measure of the accessibility of the public space network, a less prominent variable in literature to date. This variable is called herein configurational accessibility, calculated using Space Syntax, an urban morphology theory. The relevance of configurational accessibility is probably related to its surprising ability to synthesize global and perceived properties of street networks at the same time. The findings introduce the idea that the configuration of the urban grid can influence the proportion of pedestrians (as a part of total trips in any transport mode) who choose to walk on single-journey trips. The discussion links with the current debate about walkability indexes and the need of empirical support for the chosen variables and also with transport planning. Because the relevance of the street network’s role is not so easy to grasp, inputs from configurational theory and the pedestrian potential underlying this fact are also discussed at the end of the paper.     

Viewpoints of adults with and without Autism Spectrum Disorders on public transport

BackgroundPublic transport is low cost, allows for independence, and facilitates engagement and participation for non-drivers. However, the viewpoints of individuals with cognitive disabilities are rarely considered. In Australia, the prevalence of Autism Spectrum Disorders (ASD) is approximately 1% and increasing. Many individuals with ASD do not possess a driver’s licence, indicating that access to public transport is crucial for their independence. However, at present, there is no research on the opinions of adults with ASD on public transport.AimTo identify the viewpoints of adults with ASD regarding the barriers and facilitators of public transport usage and their transportation preferences, and to contrast these against the viewpoints of neurotypical adults.MethodsQ method was used to identify the viewpoints of both participant groups on public transport. Participants consisted of 55 adults with a diagnosis of ASD and a contrast group of 57 neurotypical adults. Both groups completed a Q sort task which took place in either Perth or Melbourne, Australia.ResultsThe most prominent viewpoint indicated that both groups preferred to use public transport over driving and believed that it supported their independence. This viewpoint also indicated that both groups preferred to use electronic ticketing when using public transport. Interestingly, the second most prominent viewpoint indicated that both groups preferred to drive themselves by private car rather than use public transport.DiscussionIt appears that the viewpoints of adults with and without ASD regarding public transportation were largely similar. However, questions arose about whether the preference for public transport in the ASD group may be more a result of difficulties obtaining a driving licence than a deliberate choice. The only barrier specified by adults with ASD related to crowding on public transport. Safety and convenience in relation to location and timing of services were barriers reported by neurotypical adults.     

沥青路面设计与施工中弯沉指标初探

在路基、路面工程验收中常常发现:同一碾压层在相同碾压条件下通过弯沉指标总比通过压实指标容易得多,两种指标同是用于检验路基、路面的碾压质量的,对此差异的产生进行了分析和讨论。     

社会偏好视野下旅游出行服务链定价博弈模型

为综合分析社会偏好理论视野下的服务链定价策略博弈问题,本文构建了服务提供商和出行即服务(Mobility as a Service, MaaS)平台组成的旅游出行服务链联盟。基于社会偏好理论建立不平等厌恶决策模式、利他决策模式和社会福利综合决策模式下的Stackelberg博弈模型,与分散决策和合作决策两种服务链基本决策模式下的博弈结果进行比较。探究MaaS环境下考虑决策者社会偏好特征的旅游出行服务产品的定价策略及服务链收益,并通过数值分析验证了模型的有效性。结果表明,决策权的分散导致旅游出行服务产品的销售价格和服务链整体最优收益降低。不平等厌恶决策模式下,产品的最优销售价格不受影响,服务链整体利润不变;利他决策模式下,服务链整体最优收益不断上升;社会福利综合决策模式下,各最优决策变量受服务提供商利他偏好的影响更大。关注服务链决策者的不平等厌恶偏好并实施利他行为,可以提高旅游出行服务产品的需求和总体收益,有利于旅游出行服务链的协调运营状态,实现交旅融合发展。     

双馈系统中双PWM变换器的热设计

大功率电能变换器的损耗和散热问题必须认真考虑,本文结合双馈系统中的双PWM变换器介绍了热设计的基本理论和相关计算,对类似系统有一定的参考价值。