Impact of road gradient on energy consumption of electric vehicles

We investigate the impact of road gradient on the electricity consumption of electric vehicles (EVs) by combining long-term GPS tracking data with digital elevation map (DEM) data for roads in Aichi prefecture, Japan. Eight regression models are constructed and analysed to compare the differences between linear and logarithmic forms of trip energy consumption, differences between considering the road gradient or not, and differences between considering the fixed effects of EVs or not. By categorizing gradients and assigning a percentage of the trip distance to each category, a significantly better model of electricity consumption can be achieved. The results of this study are a novel contribution toward understanding the challenges and benefits associated with downgrade braking on energy regeneration.     

Increased energy efficiency in short sea shipping through decreased time in port

According to a range of assessments, there exists a large cost-effective potential to increase energy efficiency in shipping through reduced speed at sea enabled by shorter time in port. This means that the energy needed can be reduced whilst maintaining the same transport service. However, the fact that a large cost-effective potential has been identified that is not being harnessed by decision-makers in practice suggests that there is more to this potential to understand. In this paper, the possibilities for increasing energy efficiency by reducing waiting time in port are explored and problematised through a case study of a short sea bulk shipping company transporting dry bulk goods mainly in the North and Baltic seas. Operational data from two ships in the company’s fleet for one year showed that the ships spent more than 40% of their time in ports and that half of the time in port was not productive. The two most important reasons for the large share of unproductive time were that ports were closed on nights and weekends and that ships arrived too early before the stevedores were ready to load or unload the cargo. Reducing all of the unproductive time may be difficult, but the results also show that even a conservative estimate of one to four hours of reduced time per port call would lead to a reduction in energy use of 2–8%. From in-depth interviews with employees of the shipping company, ports and ship agencies, a complex picture is painted when attempting to understand how this potential arises. Aspects such as a lack of effective ship-shore-port communication, little time for ship operators, an absence of means for accurately predicting energy use of voyages as a function of speed, perceived risk of arriving too late, and relationships with third-party technical management may all play a role.     

Interface design considerations for an in-vehicle eco-driving assistance system

This high-fidelity driving simulator study used a paired comparison design to investigate the effectiveness of 12 potential eco-driving interfaces. Previous work has demonstrated fuel economy improvements through the provision of in-vehicle eco-driving guidance using a visual or haptic interface. This study uses an eco-driving assistance system that advises the driver of the most fuel efficient accelerator pedal angle, in real time. Assistance was provided to drivers through a visual dashboard display, a multimodal visual dashboard and auditory tone combination, or a haptic accelerator pedal. The style of advice delivery was varied within each modality. The effectiveness of the eco-driving guidance was assessed via subjective feedback, and objectively through the pedal angle error between system-requested and participant-selected accelerator pedal angle. Comparisons amongst the six haptic systems suggest that drivers are guided best by a force feedback system, where a driver experiences a step change in force applied against their foot when they accelerate inefficiently. Subjective impressions also identified this system as more effective than a stiffness feedback system involving a more gradual change in pedal feedback. For interfaces with a visual component, drivers produced smaller pedal errors with an in-vehicle visual display containing second order information on the required rate of change of pedal angle, in addition to current fuel economy information. This was supported by subjective feedback. The presence of complementary audio alerts improved eco-driving performance and reduced visual distraction from the roadway. The results of this study can inform the further development of an in-vehicle assistance system that supports ‘green’ driving.     

Regional climate impact of aerosols emitted by transportation modes and potential effects of policies on demand and emissions

The transportation system is one of the main sectors with significant climate impact. In the U.S. it is the second main emitter of carbon dioxide. Its impact in terms of emission of carbon dioxide is well recognized. But a number of aerosol species have a non-negligible impact. The radiative forcing due to these species needs to be quantified. A radiative transfer code is used. Remote sensing data is retrieved to characterize different regions. The radiative forcing efficiency for black carbon are 396 ± 200 W/m²/AOD for the ground mode and 531 ± 190 W/m²/AOD for the air transportation, under clear sky conditions. The radiative forcing due to contrail is 0.14 ± 0.06 W/m² per percent coverage. Based on the forcing from the different species emitted by each mode of transportation, policies may be envisioned. These policies may affect demand and emissions of different modes of transportation. Demand and fleet models are used to quantify these interdependencies. Depending on the fuel price of each mode, mode shifts and overall demand reduction occur, and more fuel efficient vehicles are introduced in the fleet at a faster rate. With the introduction of more fuel efficient vehicles, the effect of fuel price on demand is attenuated. An increase in fuel price of 50 cents per gallon, scaled based on the radiative forcing of each mode, results in up to 5% reduction in emissions and 6% reduction in radiative forcing. With technologies, significant reduction in climate impact may be achieved.     

The trade‐off between efficiency,effectiveness, and social feasibility of regulating road transport externalities

This paper discusses the tension between the theory and practice of the regulation of road transport externalities from the viewpoint of the trade‐off between efficiency, effectiveness and the social feasibility of regulation. Various possible types of regulatory instruments, subdivided into ‘direct’ demand management, ‘indirect’ demand management and ‘supply side’ oriented policies, are evaluated qualitatively according to these criteria. Attention is then directed towards the trade‐off between efficiency, effectiveness and feasibility within the field of ‘direct’ demand regulation of road transport.     

Energy savings in light rail through the optimization of heating and ventilation

This paper discusses the potential for energy savings in heating and ventilation of light rail vehicles. We present the results of a detailed monitoring campaign on one articulated tram in Ghent, Belgium. The results give insight in the energy use for heating and ventilation in light rail as a function of ambient weather conditions. After several months of monitoring, changes in the HV strategy were implemented and the monitoring was continued. Based on this monitoring data, an energy-use model was constructed for HV both before and after the heating and ventilation strategy changes. These models then served as input for a Monte Carlo simulation, providing average energy savings over 1 year as a result of the optimized heating and ventilation strategy.     

国外员工缺勤行为研究的三种分析范式：一个归纳性述评

员工缺勤问题一直备受社会科学共同体关注,早期的研究以工业心理学和组织行为学为主导视角,后逐渐扩展到社会学和经济学领域。梳理已有的研究文献,关于员工缺勤行为的分析范式可以分为三大类：“个体一动机”、“社会一文化”和“经济一效用”,每种分析范式都以自己独特的“思想方法”观察和分析了现实生活中的员工缺勤行为,综合来看,缺勤行为应是由个人、社会和经济力量联合驱动或影响的。WANGLi’,LIUXin2     

隧道三台阶七步法的工效研究

铁路大断面隧道三台阶七步开挖法目前已经在黄土、强风化岩层等Ⅳ、Ⅴ级软弱围岩隧道施工中普遍采用。但由于湿喷设备、施工工艺衔接等诸多原因,隧道施工工效低下。因此研究开发了松土器、三喷头湿喷机械手等设备,不断优化了三台阶七步开挖法施工工艺,显著地提高了施工效能,其研究成果在沪昆客专云南段大坪地隧道出口得到成功应用。     

盾构施工组织因素与掘进效率关系的研讨——以石家庄地铁1号线06标段为例

为了提高施工效率,缩短工期,通过对施工组织因素的提前预控和施工过程中的重点管控,盾构始发施工比原工期策划提前了3个月,通过优化施工组织减少了盾构投入。本文以石家庄地铁1号线06标段为例,重点分析盾构施工组织因素与施工效率的关系。