Assessing the impact of cornering losses on the energy consumption of electric city buses

In view of the increasing electrification of public city transport, an accurate energy consumption prediction for Battery Electric Buses (BEBs) is essential. Conventional prediction algorithms do not consider energy losses that occur during turning of the vehicle. This is especially relevant for electric city buses, which have a limited battery capacity and often drive curvy routes.In this paper, the additional energy consumption during steering of a BEB is modeled, measured, and assessed. A nonlinear steady-state cornering model is developed to establish the additional energy losses during cornering. The model includes large steer angles, load transfer, and a Magic Formula tire model. Model results show that both cornering resistance and tire scrub of the rear tires cause additional energy losses during cornering, depending on the corner radius and vehicle velocity.The energy consumption model is validated with full scale vehicle tests and shows an average deviation of 0.8 kW compared to the measurements. Analysis of recorded real-world bus routes reveals that on average these effects constitute 3.1% of the total powertrain energy. The effect is even more significant for routes crossing city centers, reaching values up to 5.8%. In these cases, cornering losses can be significant and should not be neglected in an accurate energy consumption prediction.     

某公务船抗碰撞性能研究

公务船在领海和专属经济区执行维权执法任务时,存在较高的与其他船舶发生主动或被动碰撞的风险。为了准确评估公务船的耐撞性能,本文以某公务船为例,考虑多种计算工况,对目标船的耐撞性能进行动态响应计算,获得了机舱及首部区域的结构损伤、应力、能量吸收等动态结构响应,并计算获得被撞船达到临界状态时的极限撞击速度。研究成果可为公务船的防撞结构设计提供参考。     

Cost benefit analysis of three different urban bus drive systems using real driving data

One of the CIVITAS-ELAN project measures in Ljubljana, Slovenia, was the introduction of alternative city bus propulsion systems (CNG, hydraulic hybrid buses) into the public transport and comparison of their performance in terms of costs and benefits with conventional (diesel) buses. A cost-benefit analysis was conducted to provide a model for identifying the most attractive alternative, with aim of aiding the decision making process for future rational up-scaling of the alternative propulsion technologies in PT fleet in Ljubljana. This paper focuses on presenting the key findings of this CBA, using real driving data, while demonstrating the sensitivity/variance of different parameters of a CBA, as well as the differentiation between uncertainties of parameters in an ex-ante analysis versus an ex-post analysis.     

Organizational adoption behavior of CO2-saving power train technologies: An empirical study on the German heavy-duty vehicles market

This study analyzes the preference structure of buyer groups that influences their willingness to select CO₂-saving power train technologies for medium-duty and heavy-duty vehicles (HDV). Based on the Technology–Organization–Environment framework for organizational adoption decision making and organizational buying criteria a theoretical construct was developed. Variables were validated in exploratory preliminary research and subsequently tested based on factor analysis using 27 survey items in a quantitative web-based study among 177 organizations operating HDV in Germany. Knowledge, experience, use and purchase consideration concerning alternative power train technologies and further measures to reduce fuel consumption were additionally queried. Based on a multiple linear regression analysis, key findings show that at the current stage of market maturity environmental attitude and corporate social responsibility exert the strongest significant influence on willingness to select CO₂-saving power train technologies. A hierarchical cluster analysis revealed six customer groups in order to yield behavioral market segmentation. Hereby it is shown that the performed transportation tasks do not determine the preference structures. Early adopting organizations are larger than average and driven by non-economic aspects as image or corporate social responsibility, whereas the mass market awaits lower purchasing prices. Crossing this chasm will be a major challenge for policymaker and manufacturers.     

Multi-criteria analysis of optimal signal plans using microscopic traffic models

Increasing concerns on environment and natural resources, coupled with increasing demand for transport, put lots of pressure for improved efficiency and performance on transport systems worldwide. New technology nowadays enables fast innovation in transport, but it is the policy for deployment and operation with a systems perspective that often determines success. Smart traffic management has played important roles for continuous development of traffic systems especially in urban areas. There is, however, still lack of effort in current traffic management and planning practice prioritizing policy goals in environment and energy. This paper presents an application of a model-based framework to quantify environmental impacts and fuel efficiency of road traffic, and to evaluate optimal signal plans with respect not only to traffic mobility performance but also other important measures for sustainability. Microscopic traffic simulator is integrated with micro-scale emission model for estimation of emissions and fuel consumption at high resolution. A stochastic optimization engine is implemented to facilitate optimal signal planning for different policy goals, including delay, stop-and-goes, fuel economy etc. In order to enhance the validity of the modeling framework, both traffic and emission models are fine-tuned using data collected in a Chinese city. In addition, two microscopic traffic models are applied, and lead to consistent results for signal optimization. Two control schemes, fixed time and vehicle actuated, are optimized while multiple performance indexes are analyzed and compared for corresponding objectives. Solutions, representing compromise between different policies, are also obtained in the case study by optimizing an integrated performance index.     

The Role of Tradable Credit Schemes in Road Traffic Congestion Management

Abstract

Road traffic congestion is not yet reflected in current market prices within the sector and has given rise to a number of instruments to mitigate the resulting negative impacts. The focus of this paper is the tradable credit scheme — an incentive-based economic measure — in order to address traffic congestion. The research questions are (1) whether the state-of-the-art in the literature suggests that tradable credit schemes could be feasibly introduced to mitigate congestion, and (2) whether a tradable credit scheme could have advantages over other instruments. A brief outline of congestion mitigation approaches is provided first to position this type of economic instrument with respect to other measures. The broad issues in the design of a tradable credit scheme are then presented. Most research to date has focused on the use of tradable credits to manage related pollution, but it is clear there is potential to design a scheme for traffic congestion management. To date this is a novel review of tradable credit schemes that has focused specifically on their role in road traffic congestion management.     

A fuel tankering model applied to a domestic airline network

This paper presents a linear programming model designed to determine the optimum fuel loading quantities along a route network for a Brazilian domestic airline. Assuming that there are no volume purchase or storage capacity restrictions on each station, the analysis is carried out for one aircraft on one day of its schedule. Results are extrapolated for a monthly and yearly basis. Through the proposed model, it is seen that such a fuel tankering technique leads to a 5% economical saving, but produces a 1% additional fuel burn. A discussion on the environmental impact for this procedure is also proposed. Copyright © 2011 John Wiley & Sons, Ltd.     

城市110KV户内变电站声场数值模拟

摘要：城市户内变压器运转时会产生噪声,严重时会影响到周围居民的正常工作和生活。文章简单阐述了变压器噪声产生和传播机理。并以南昌市某户内变电站为例,使用声振软件Va One,基于统计能量方法,对经过吸声材料处理后的户内变声场进行仿真模拟。模拟结果表明：经过添加特殊吸声材料处理后的户内变电站,在大门外,仿真数据与实测值吻合良好;在大门内、外,声压级差值仿真结果与预期效果能够符合。     

长三角集装箱公路运输与水陆联运比较

以苏州经由洋山港进出口的集装箱货物运输为例,通过计算集装箱运输成本、CO2排放量和交通流量等3个指标,分析了集装箱公路运输和水陆联运的优劣。研究表明:苏州至洋山港集装箱水陆联运的成本优势不明显,但对环境保护和城市交通方面起到很大的作用,对长三角水水中转意义重大。     

天然气汽车的应用

由于汽车尾气排放对环境造成的污染日益严重,以及石油资源逐渐减少,很多国家都在大力发展新能源汽车。天然气汽车与燃油汽车相比,能大大地减少污染物排放,具有良好的环保性、经济性及安全性,在国内外有着成熟而广泛的应用,是改善城市大气环境快捷有效途径。因此,为减少对石油的依赖以及机动车尾气造成的大气污染,推广天然气汽车的力度还需进一步加大,在尽可能短的时间内培养出一个比较成熟的天然气汽车市场,为实现可持续发展提供保证。