Design of 2-speed transmission for electric commercial vehicle

As environmental and economic interests increase, the need for eco-friendly vehicle such as an electric vehicle (EV) has increased rapidly. Various research of enhancing EV powertrain efficiency and relibility have been studied. In this study, 2-speed shift gears mechanism is designed by using simpson type planetary gear train. This transmission has two planetary gear unit. Gear position is determinded by which ring gear is fixed. Internal components of the transmission are designed for satisfying the required specification of EV. We analyze gear strength, gear mesh efficiency, and transmission efficiency. By manufacturing the transmission prototype and performing some experiments, we verify the application suitability of this transmission.     

Plug-in HEV with CVT: configuration,control, and its concurrent multi-objective optimization by evolutionary algorithm

Plug-in Hybrid Electric Vehicle (Plug-in HEV) has dramatic improvements in fuel economy and emission reduction. It is most important to decide its optimal configuration, energy management strategy, powertrain sizes, and control logic parameters. For multi-objective optimization, we present a concurrent optimization methodology based on an optimal Plug-in HEV powertrain configuration with continuous variable transmission (CVT). The novelty is using evolutionary algorithm in conjunction with an instantaneous optimal energy management strategy. Simulation results indicate the proposed method can significantly reduce fuel consumption and emissions by simultaneously optimizing the propulsion system parameters as well as the energy control parameters.     

Engine performance powered by a mixture of hydrogen and oxygen fuel obtained from water electrolysis

In this work, the performance of an SI engine powered with both gasoline and HHO as supplement fuel was studied and compared with pure gasoline-fuelled engine. The amount of HHO gas quantities added was 1, 1.5, and 2 LPM. The engine speed was varied from 1350 to 2250 rpm. The performance was found by measuring the engine torque, the brake power, the brake specific fuel consumption and the thermal efficiency, while gas analyzer was used to measure the amounts of nitrogen oxides and carbon dioxide that are emitted from the engine during operation. It was found that the engine performance was best when 2 LPM HHO gas was used with pure gasoline fuel. Further, it was found that, at high amount of HHO gas addition, the nitrogen oxide decreases. Further, the CO level increased when using HHO gas as supplement fuel.     

Accounting for travel time variability in the optimal pricing of cars and buses

A number of studies have shown that in addition to travel time and cost as the common influences on mode, route and departure time choices, travel time variability plays an increasingly important role, especially in the presence of traffic congestion on roads and crowding on public transport. The dominant focus of modelling and implementation of optimal pricing that incorporates trip time variability has been in the context of road pricing for cars. The main objective of this paper is to introduce a non-trivial extension to the existing literature on optimal pricing in a multimodal setting, building in the role of travel time variability as a source of disutility for car and bus users. We estimate the effect of variability in travel time and bus headway on optimal prices (i.e., tolls for cars and fares for buses) and optimal bus capacity (i.e., frequencies and size) accounting for crowding on buses, under a social welfare maximisation framework. Travel time variability is included by adopting the well-known mean–variance model, using an empirical relationship between the mean and standard deviation of travel times. We illustrate our model with an application to a highly congested corridor with cars, buses and walking as travel alternatives in Sydney, Australia. There are three main findings that have immediate policy implications: (i) including travel time variability results in higher optimal car tolls and substantial increases in toll revenue, while optimal bus fares remain almost unchanged; (ii) when bus headways are variable, the inclusion of travel time variability as a source of disutility for users yields higher optimal bus frequencies; and (iii) including both travel time variability and crowding discomfort leads to higher optimal bus sizes.     

Assessing the employment agglomeration and social accessibility impacts of high speed rail in Eastern Australia

There is growing interest in establishing additional evidence, under the umbrella of the wider economy impacts of transport infrastructure projects, to support transport projects in general and public transport projects in particular that struggle to obtain benefit–cost ratios sufficient to gain the support of financial agencies. This paper focuses on one element of wider economy impacts, often referred to as effective economic (employment) density or employment agglomeration impacts, and another, less usually identified, social accessibility impact (SAI) which we refer to as effective social density, which in broad terms provide, correspondingly, evidence of the potential gains in work-related output (often referred to as productivity gains) and potential gains in non-work-related outputs. Both are associated with gains in individual and household benefit attributable to improved accessibility to services linked with populations and particular locations. The SAIs may capture some of the induced benefits in those jurisdictions where these are included routinely in benefit–cost analysis, and the methodology here is most appropriate to those settings where an existing calibrated demand curve may not be available. Using the proposed high speed rail (HSR) project between Sydney and Melbourne as the empirical setting, we identify economic agglomeration and social accessibility benefits for work and non-work related activity respectively. We find the former to be relatively small compared to the significant gains associated with non-work related travel activity, suggesting the greatest benefits associated with HSR, especially for those residents outside of the major metropolitan areas, will be non-work related travel activity.     

Analysis of train derailment after hitting the pier of tongling yangtze river bridge combined road with railwayEI北大核心

Research purposes: Precise prediction for mechanical behavior of the bridge under ship collision force is important to assess the analysis of train derailment after hitting the pier. This paper focuses on the Tongling Yangtze River Bridge Combined Road with Railway for ship collision simulation, uses the nonlinear finite element software of ANSYS/LS-DYNA to simulate the ship's bow section of 10000 t and 5000 t class hitting bridge tower column at front and axle to 20° of side in highest navigable water level, conventional navigable water level and the minimum navigable water level. Curves of collision force-period at different working conditions are summarized. On this basis, when the impact load affects as input loads, the displacement and acceleration response can be used by finite element analysis under the collision and study the dynamic response of the bridge caused by a train derailment risk. Research conclusions: (1) The impact force of the bridge is largest when a laden ship is hitting the pier at the highest navigable water level. In the most unfavorable condition, the collision have lardge impact on bridge structure and derailment risk of trains. (2) The transverse acceleration of the girder on the top of 2# pier can reach to 0.922 m/s2, but it does not exceed acceleration excitation limit (1 m/s2) when 3# piers are hitted by the 10000 t ship at the peak load of collision, so the probability of train derailment is minimal. (3) Based on the probability formula of the derailment by simplifying risk criteria, the derailment probability of train is 9×10-5~1.5×10-4 during the ship-bridge collision. (4) The research results can provide the reference for train traffic safety on railway bridge caused by ship collisions.     

A network equilibrium approach for modelling activity-travel pattern scheduling problems in multi-modal transit networks with uncertainty

An understanding of the interaction between individuals’ activities and travel choice behaviour plays an important role in long-term transit service planning. In this paper, an activity-based network equilibrium model for scheduling daily activity-travel patterns (DATPs) in multi-modal transit networks under uncertainty is presented. In the proposed model, the DATP choice problem is transformed into a static traffic assignment problem by constructing a new super-network platform. With the use of the new super-network platform, individuals’ activity and travel choices such as time and space coordination, activity location, activity sequence and duration, and route/mode choices, can be simultaneously considered. In order to capture the stochastic characteristics of different activities, activity utilities are assumed in this study to be time-dependent and stochastic in relation to the activity types. A concept of DATP budget utility is proposed for modelling the uncertainty of activity utility. An efficient solution algorithm without prior enumeration of DATPs is developed for solving the DATP scheduling problem in multi-modal transit networks. Numerical examples are used to illustrate the application of the proposed model and the solution algorithm.     

Dynamic system‐optimal traffic assignment for a city using the continuum modeling approach

This paper presents a continuum dynamic traffic assignment model for a city in which the total cost of the traffic system is minimized: the travelers in the system are organized to choose the route to their destinations that minimizes the total cost of the system. Combined with the objective function, which defines the total cost and constraints such as certain physical and boundary conditions, a continuum model can be formulated as an optimization scheme with a feasible region in the function space. To obtain an admissible locally optimal solution to this problem, we first reformulate the optimization in discrete form and then introduce a heuristic method to solve it. This method converges rapidly with attractive computational cost. Numerical examples are used to demonstrate the effectiveness of the method. Copyright © 2013 John Wiley & Sons, Ltd.     

A review of shipboard large-scale energy storage systems北大核心CSCD

储能系统是船舶中的重要设备,可为各类船舶负荷提供能源。随着电力推进技术的成熟,全电船舶已成为未来船舶设计的主要方向。在此背景下,储能系统将由主要为辅助负荷供能逐步发展到为多类型船舶负荷供能,特别是作为船舶动力系统的重要组成部分与各类船舶主/辅机配合,在满足船舶各类负荷需求的前提下提高船舶的经济/环保特性。功能角色的转变加速了大规模储能系统接入船舶,带来了储能系统的状态估计、能量管理、优化规划等一系列问题。首先,对目前的储能技术进行分类;然后,介绍典型全电船舶的分类方法并指出储能系统的应用场景;最后,提出大容量储能系统接入船舶后带来的若干亟待解决的技术问题,即船舶储能系统分布式控制、船舶储能系统适应性规划与优化,以及船舶储能系统状态评估。所做研究可为未来大规模储能系统在电力化船舶上的应用研究提供参考方向。     

Optimize combustion of compressed natural gas engine by improving in-cylinder flows

In order to solve the problem of slow flame propagation in a spark-ignition engine fueled with compressed natural gas (CNG), the influence of in-cylinder flows on combustion process was investigated in CA6SE3-21E4N CNG-engine by means of numerical simulation and experiment. The status of in-cylinder flows from intake to expansion stroke was described by computational fluid dynamic tool, which revealed that the in-cylinder flows were one of the main reasons of slow burning rate. Therefore, a special-shaped combustion chamber called Cross was used to improve the in-cylinder flows. The results showed that peak turbulent kinetic energy of Cross was 43.9% higher than that of original combustion chamber called Cylinder during the late compression period at 1450 rpm 100% load. The combustion parameters, brake specific fuel consumption (BSFC) and regulated emissions were obtained by means of experiment. At 1450rpm 25%, 50%, 75% and 100% load conditions, the ignition delay of Cross was longer than that of Cylinder, moreover, the Cross produced averagely 5.75°CA shorter combustion duration. The BSFC of Cross was on an average of 4.3% reduction at 1450 rpm as well as the HC and CO emissions were reduced whereas the NOx emissions were significantly increased.