Comparative analysis of the energy consumption and CO2 emissions of 40 electric,plug-in hybrid electric,hybrid electric and internal combustion engine vehicles

This paper analyses the results of the Royal Automobile Clubhallo’s 2011 RAC Future Car Challenge, an annual motoring challenge in which participants seek to consume the least energy possible while driving a 92 km route from Brighton to London in the UK. The results reveal that the vehicle’s power train type has the largest impact on energy consumption and emissions. The traction ratio, defined as the fraction of time spent on the accelerator in relation to the driving time, and the amount of regenerative braking have a significant effect on the individual energy consumption of vehicles. In contrast, the average speed does not have a great effect on a vehicles’ energy consumption in the range 25–70 km/h.     

An energy-efficient scheduling approach to improve the utilization of regenerative energy for metro systems

Regenerative braking is an energy recovery mechanism that converts the kinetic energy during braking into electricity, also known as regenerative energy. In general, most of the regenerative energy is transmitted backward along the pantograph and fed back into the overhead contact line. To reduce the trains’ energy consumption, this paper develops a scheduling approach to coordinate the arrivals and departures of all trains located in the same electricity supply interval so that the energy regenerated from braking trains can be more effectively utilized to accelerate trains. Firstly, we formulate an integer programming model with real-world speed profiles to minimize the trains’ energy consumption with dwell time control. Secondly, we design a genetic algorithm and an allocation algorithm to find a good solution. Finally, we present numerical examples based on the real-life operation data from the Beijing Metro Yizhuang Line in Beijing, China. The results show that the proposed scheduling approach can reduce energy consumption by 6.97% and save about 1,054,388 CNY (or 169,223 USD) each year in comparison with the current timetable. Compared to the cooperative scheduling (CS) approach, the proposed scheduling approach can improve the utilization of regenerative energy by 36.16% and reduce the total energy consumption by 4.28%.     

Optimum routing of battery electric vehicles: Insights using empirical data and microsimulation

This study investigates the energy consumption impact of route selection on battery electric vehicles (BEVs) using empirical second-by-second Global Positioning System (GPS) commute data and traffic micro-simulation data. Drivers typically choose routes that reduce travel time and therefore travel cost. However, BEVs’ limited driving range makes energy efficient route selection of particular concern to BEV drivers. In addition, BEVs’ regenerative braking systems allow for the recovery of energy while braking, which is affected by route choices. State-of-the-art BEV energy consumption models consider a simplified constant regenerative braking energy efficiency or average speed dependent regenerative braking factors. To overcome these limitations, this study adopted a microscopic BEV energy consumption model, which captures the effect of transient behavior on BEV energy consumption and recovery while braking in a congested network. The study found that BEVs and conventional internal combustion engine vehicles (ICEVs) had different fuel/energy-optimized traffic assignments, suggesting that different routings be recommended for electric vehicles. For the specific case study, simulation results indicate that a faster route could actually increase BEV energy consumption, and that significant energy savings were observed when BEVs utilized a longer travel time route because energy is regenerated. Finally, the study found that regenerated energy was greatly affected by facility types and congestion levels and also BEVs’ energy efficiency could be significantly influenced by regenerated energy.     

Energy conservation in urban public transport

Urban public transport energy use is determined largely by the weight of the vehicle, and frequency of intermediate stops, imposing repeated acceleration/steady running/braking cycles, in which much of the kinetic energy is dissipated. Energy consumed for the same capacity and vehicle performance may be reduced by coasting, cutting vehicle weight, and use of regenerative braking, on electrically‐powered systems, to convert the otherwise wasted braking energy into useful form. Particular attention is paid to the last‐named, identifying results of past experience and recent simulations. Practical constraints limiting the amount of energy actually recovered are discussed, including proportion of vehicle weight braked electrically, receptivity of the supply system, stop spacing and number of vehicles operated simultaneously. Reference is also made to battery vehicles and flywheel energy storage.

It is suggested that considerable scope exists in urban electric rail operation for reduced energy consumption, as existing fleets are replaced by lighter weight vehicles, fitted for regenerative braking. Further savings may come from use of inverter equipment. Rate of fleet renewal may be an important factor. Buses are already much more energy efficient, and dramatic gains are unlikely. However, there is some scope for use of flywheel energy storage, and regenerative braking on trolleybuses.     

To save money or to save time: Intelligent routing design for plug-in hybrid electric vehicle

Electric vehicles (EVs) are promising alternative to conventional vehicles, due to their low fuel cost and low emissions. As a subset of EVs, plug-in hybrid electric vehicles (PHEVs) backup batteries with combustion engines, and thus have a longer traveling range than battery electric vehicles (BEVs). However, the energy cost of a PHEV is higher than a BEV because the gasoline price is higher than the electricity price. Hence, choosing a route with more charging opportunities may result in less fuel cost than the shortest route. Different with the traditional shortest-path and shortest-time routing methods, we propose a new routing choice with the lowest fuel cost for PHEV drivers. Existing algorithms for gasoline vehicles cannot be applied because they never considered the regenerative braking which may result in negative energy consumption on some road segments. Existing algorithms for BEVs are not competent too because PHEVs have two power sources. Thus, even if along the same route, different options of power source will lead to different energy consumption. This paper proposes a cost-optimal algorithm (COA) to deal with the challenges. The proposed algorithm is evaluated using real-world maps and data. The results show that there is a trade-off between traveling cost and time consumed when driving PHEVs. It is also observed that the average detour rate caused by COA is less than 14%. Significantly, the algorithm averagely saves more than 48% energy cost compared to the shortest-time routing.     

Cutting vehicle emissions with regenerative braking

This paper presents an analysis of vehicle regenerative braking systems as a quick and relatively easy means of achieving higher overall fuel efficiency and lowering carbon emissions. The system involves the installation of an additional electric motor/generator in parallel to the vehicle’s internal combustion engine and is used in conjunction with a DCDC converter and ultracapacitor. The system is used to recapture the energy lost in vehicle braking, significantly reducing a vehicle’s overall energy consumption and lowering vehicle emissions. Experimentally-based evidence is collected and compared for two sample vehicles to deduce the potential fuel and emissions saving.     

Equilibrium holdings distributions in durable asset markets

The stock of durable goods can be represented by its holdings distribution, defined as the joint distribution of age and physical condition of the population of durable goods. This paper derives the holdings distribution which arises under stationary conditions when durable goods deteriorate according to a Markov process. We show that given the scrappage and utilization decisions of consumers, the holdings distribution F(x) is an equilibrium distribution of an associated regenerative Markov process. Using a basic result from the theory of regenerative stochastic processes, we characterize F(x) as the ratio of the expected number of periods the durable's condition is better than x to the expected lifetime of the asset. Using data from the 1977 National Transportation Survey we illustrate these results by estimating a simple two-parameter model of automobile deterioration and comparing the implied distribution of automobile holdings to the actual distribution.     

沥青路面再生过程中混合料路用特性的恢复分析

沥青路面材料的再生利用是道路交通领域固废利用及节能环保的重点项目。随着我国道路通车里程的快速增加和道路等级的不断提高,路面材料再生的质量要求也更为严格。如何达到相应的技术要求是衡量再生沥青混合料(RAP)性能质量的基本条件。在材料再生过程中,根据旧料中沥青的老化程度及矿料级配的变化等提出新料掺配的量化数据,以及专用机械设备的选取和配套作业工艺,是保证RAP用于道路铺筑质量的前提条件。     

On the relationship between airport pricing models

Airport pricing papers can be divided into two approaches. In the traditional approach the demand for airport services depends on airport charges and on congestion costs of both passengers and airlines; the airline market is not formally modeled. In the vertical-structure approach instead, airports provide an input for an airline oligopoly and it is the equilibrium of this downstream market which determines the airports’ demand. We prove, analytically, that the traditional approach to airport pricing is valid if air carriers have no market power, i.e. airlines are atomistic or they behave as price takers (perfect competition) and have constant marginal operational costs. When carriers have market power, this approach may result in a surplus measure that falls short of giving a true measure of social surplus. Furthermore, its use prescribes a traffic level that is, for given capacity, smaller than the socially optimal level. When carriers have market power and consequently both airports and airlines behave strategically, a vertical-structure approach appears a more reasonable approach to airport pricing issues.     

瀑布沟水电站地下厂房顶拱层开挖与爆破震动控制

特大型地下厂房顶拱层开挖和爆破震动控制,涉及整个工程项目的工期、成本及施工安全,所以一直是施工中的最关键工序。文章介绍了瀑布沟水电站在高地应力复杂地质条件下,特大型地下厂房顶拱层开挖与爆破震动控制的施工经验,可供同类工程借鉴。     

The key principles of optimal train control—Part 2: Existence of an optimal strategy,the local energy minimization principle,uniqueness, computational techniques

We discuss the problem of finding an energy-efficient driving strategy for a train journey on an undulating track with steep grades subject to a maximum prescribed journey time. In Part 1 of this paper we reviewed the state-of-the-art and established the key principles of optimal train control for a general model with continuous control. We assumed only that the tractive and braking control forces were bounded by non-increasing speed-dependent magnitude constraints and that the rate of energy dissipation from frictional resistance was given by a non-negative strictly convex function of speed. Partial cost recovery from regenerative braking was allowed. Our aim was to minimize the mechanical energy required to drive the train. We examined the characteristic optimal control modes, studied allowable control transitions and established the existence of optimal switching points. We found algebraic formulae for the adjoint variables in terms of speed on track with piecewise-constant gradient and drew phase plots of the associated optimal evolutionary lines for the state and adjoint variables. In Part 2 we will establish integral forms of the necessary conditions for optimal switching, find general bounds on the positions of the optimal switching points, justify an extended local energy minimization principle and show how these ideas can be used to calculate the optimal strategy. We prove that an optimal strategy always exists and use a perturbation analysis to show that the optimal strategy is unique. Finally we discuss computation of optimal switching points in two realistic examples with steep grades and describe the optimal control strategies and corresponding speed profiles for a complete journey with several different allowed journey times. In practice the strategies described here have been shown to reduce the costs of energy used by as much as 20%.     

电动自行车用氢燃料电池动力系统研究

论文研究开发了一种"电电"互混的电动自行车用氢燃料电池动力系统,旨在通过将燃料电池与一种具备瞬间大电流放电能力的储能设备连接,使得电动自行车用氢燃料电池动力系统在具备长航时、快速充装特性的同时,具备良好的爬坡与加速性能。文章提供了该电动自行车用氢燃料电池动力控制方法、电动自行车用氢燃料电池动力控制装置及包括该电动自行车用氢燃料电池动力控制装置的电动自行车用氢燃料电池动力系统,解决相关技术中存在的燃料电池的动态响应能力弱过载能力差的问题。     

A review of EVs charging: From the perspective of energy optimization,optimization approaches,and charging techniques

Introduction of electric vehicles (EVs) or plug-in electric vehicles (PEVs) in the road transportation can significantly reduce the carbon emission. Hence, the demand of EVs is likely to increase in the near future. Large penetration of EVs will also ultimately result into high loads on the existing power grids. The controlled charging of EVs can have a significant impact on the power grid load, voltage, frequency, and power losses. In this paper, we have provided a comprehensive review of various energy optimization approaches used for EVs charging. Energy optimization approaches used for EVs not only enhance the battery life but also contribute in regulating the voltage and frequency. During EVs charging, various objective functions such as supporting the renewable energy sources, minimization of the peak load, energy cost, and maximization of the aggregator profit have also been studied from optimization perspectives. The controlled and an optimized EVs charging enhances the performance of EVs batteries and conserves the energy in the system by minimizing the load and power losses. The different EVs charging approaches such as centralized and distributed suited for different objective functions have also been studied and compared with respect to various optimization approaches.     

LNG燃料动力船在广西内河推广应用的思考

文章分析了液化天然气(LNG)在航运业推广应用的必要性和以LNG作为船舶动力燃料的主要危险特性,介绍了国内外LNG燃料动力船改造应用的基本情况及难点,提出了广西内河现有船舶进行LNG动力改造面临的主要问题与对策,为LNG燃料动力船在广西内河的推广应用提供参考。     

Market power and its determinants in the Chinese airline industry

This paper first measures the degree of Chinese airlines’ market power by using Lerner index, and then investigates its determinants. Our empirical results show that a certain degree of market power exists in the Chinese airline industry. Of the three dominant carriers, Air China exhibits the strongest market power whereas China Eastern Airlines the weakest, with China Southern Airlines being in the middle. Furthermore, the extent of market power varies significantly among regional markets, with China’s northeast region as the strongest, followed by the eastern and western regions, and the central area as the weakest. We also find a hub-premium effect similar to the result found in the US airline market. Our analysis shows that the existence of high-speed rail and low-cost carriers, income level, population size, seasonality, and number of competing airlines are the main determinants of competition in the Chinese airline market.     

桂闽两省区高速公路隧道电力系统应用对比探悉

文章阐述了广西与福建两省区高速公路隧道供配电系统设计的一些特点，并对两种设计方式的技术应用进行了一系列的对比，分析了各自的优劣，以期为今后隧道供配电方案的应用和选择提供参考。     

The key principles of optimal train control—Part 1: Formulation of the model,strategies of optimal type,evolutionary lines,location of optimal switching points

We discuss the problem of finding an energy-efficient driving strategy for a train journey on an undulating track with steep grades subject to a maximum prescribed journey time. We review the state-of-the-art and establish the key principles of optimal train control for a general model with continuous control. The model with discrete control is not considered. We assume only that the tractive and braking control forces are bounded by non-increasing speed-dependent magnitude constraints and that the rate of energy dissipation from frictional resistance is given by a non-negative strictly convex function of speed. Partial cost recovery from regenerative braking is allowed. The cost of the strategy is the mechanical energy required to drive the train. Minimising the mechanical energy is an effective way of reducing the fuel or electrical energy used by the traction system. The paper is presented in two parts. In Part 1 we discuss formulation of the model, determine the characteristic optimal control modes, study allowable control transitions, establish the existence of optimal switching points and consider optimal strategies with speed limits. We find algebraic formulae for the adjoint variables in terms of speed on track with piecewise-constant gradient and draw phase plots of the associated optimal evolutionary lines for the state and adjoint variables. In Part 2 we will establish important integral forms of the necessary conditions for optimal switching, find general bounds on the positions of the optimal switching points, justify the local energy minimization principle and show how these ideas are used to calculate optimal switching points. We will prove that an optimal strategy always exists and use a perturbation analysis to show the strategy is unique. Finally we will discuss computational techniques in realistic examples with steep gradients and describe typical optimal strategies for a complete journey.     

Energy-efficient metro train rescheduling with uncertain time-variant passenger demands: An approximate dynamic programming approach

In a heavily congested metro line, unexpected disturbances often occur to cause the delay of the traveling passengers, infeasibility of the current timetable and reduction of the operational efficiency. Due to the uncertain and dynamic characteristics of passenger demands, the commonly used method to recover from disturbances in practice is to change the timetable and rolling stock manually based on the experiences and professional judgements. In this paper, we develop a stochastic programming model for metro train rescheduling problem in order to jointly reduce the time delay of affected passengers, their total traveling time and operational costs of trains. To capture the complexity of passenger traveling characteristics, the arriving ratio of passengers at each station is modeled as a non-homogeneous poisson distribution, in which the intensity function is treated as time-varying origin-to-destination passenger demand matrices. By considering the number of on-board passengers, the total energy usage is modeled as the difference between the tractive energy consumption and the regenerative energy. Then, we design an approximate dynamic programming based algorithm to solve the proposed model, which can obtain a high-quality solution in a short time. Finally, numerical examples with real-world data sets are implemented to verify the effectiveness and robustness of the proposed approaches.     

电磁感应加热在管道管口焊接预热中的应用

为适应大口径长距离管道优质高效建设的需要,采用电力半导体元件研制成功大口径管道管口中频预热设备并投入西气东输工程应用。实现了可控硅中频电源的风冷化、小型化及与自制的多功能移动电站的动力匹配;电磁感应加热器采用有断点开合结构及无断点技术,操作简便,性能可靠。克服了施工现场气候环境因素及管墩等障碍的影响,提高了管口预热综合效率,填补了国内现代感应技术在长输管道施工中应用的空白。     

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.