Deploying the advanced public transportation systems (APTS) technologies in Los Angeles: A summary and analysis

This paper first introduces the key players involved in the deployment of Intelligent Transportation Systems (ITS) technologies in the Los Angeles metropolitan area. The paper then reports the local deployment status of major Advanced Public Transportation Systems (APTS) projects, with a particular emphasis placed on the burgeoning Los Angeles Smart Shuttle Demonstration Project. In addition, the paper analyzes some technical, political, financial and other issues centering around the deployment of APTS technologies in the Los Angeles metropolitan area.     

Regulatory policy and economies of scale in the U.S. intercity bus industry

After nearly a half century of federal and state regulation, the U.S. intercity bus industry is the subject of proposals which would drastically reduce the extent of governmental control over fare setting, service abandonment, and market entry. An essential requirement for understanding how these regulatory changes might affect the industry is knowing the extent to which economies of scale are present in the provision of intercity bus services. This paper reports on the analysis of economies of scale for both Class I firms and for Class II and III firms. The results show nearly constant returns to scale beyond very low output levels but very strong dependence on the mix of charter and regular-route service provided.     

Not All Transfers Are Created Equal: Towards a Framework Relating Transfer Connectivity to Travel Behaviour

Abstract

Walking from origins to transit stops, transferring between transit lines and walking from transit stops to destinations—all add to the burden of transit travel, sometimes to a very large degree. Transfers in particular can be stressful and/or time‐consuming for travellers, discouraging transit use. As such, transit facilities that reduce the burdens of walking, waiting and transferring can substantially increase transit system efficacy and use. In this paper, we argue that transit planning research on transit stops and stations, and transit planning practice frequently lack a clear conceptual framework relating transit waits and transfers with what we know about travel behaviour. Therefore, we draw on the concepts of transfer penalties and value of time in the travel behaviour/economics literature to develop a framework that situates transfer penalties within the total travel generalized costs of a transit trip. For example, value of time is important in relating actual time of waiting and walking to the perceived time of travel. We also draw on research to classify factors most important to users’ perspectives and travel behaviour—transfer costs, time scheduling and five transfer facility attributes: (1) access, (2) connection and reliability, (3) information, (4) amenities, and (5) security and safety. Using this framework, we seek to explicitly relate improvements of transfer stops/stations with components of transfer penalties and changes in travel behaviour (through a reduction in transfer penalties). We conclude that the employment of such a framework can help practitioners better apply the most effective improvements to transit stops and transfer facilities.     

On the time dependence of survivability of ROPAX ships

The time dependence of survivability of ROPAX vessels, when sustaining side collision damage in waves, is investigated herein by use of numerical simulations of ship motion and flooding. Conducted research confirms that ROPAX ships characteristically capsize fast, when sustaining damage leading to capsizing. A probabilistic analysis of the survive time after collision damage reveals that even for the most generic damage conditions assumed, the survival time in the case of capsizing remains short, which is characteristic of this type of ship design, disposing the typically large undivided deck to be subject to flooding in higher waves. In a case study, the unconditional survivability in waves, corresponding to survival s-factor of SOLAS regulations, is alternatively assessed with numerical simulations. The estimated survivability proves to be time independent in terms of practical implications. Observed deviations between current SOLAS formulation and simulations, suggest the employment of comprehensive simulation methods when more reliable estimations and assessments of survivability are required.     

Accessible pre-design calculation tool to support the definition of EV components

The new freedoms in design that electric powertrains offer lead to a wide variety of configurations to consider when developing an electric vehicle (EV) from scratch. Furthermore, the strong relation of the battery size with vehicle weight, range and performances leads to a set of interrelated dependencies that can result in many design loops to fulfil the vehicle targets, market constraints and regulations simultaneously. The paper presents a pre-design tool to assist the electric vehicle development process by representing the different constraints and the possible feasible solutions in a single plot with the need of a small amount of inputs accesible to assess at pre-design phase. As a result, the tool depicts a set of feasible vehicle configurations that could fulfil the targets easing the interaction and loops among different expertise areas. To better assist selection, it also provides a sensitivity analysis of the performances to selected inputs and the user can introduce a cost function depending on vehicle weight and battery size. The tool is based on the vehicle longitudinal dynamics equations and equations that model the market and regulations constraints. It is aimed at providing an overview of the main specifications for component selection avoiding detailed vehicle modelling in the early pre-design phase at which the vehicle characteristics and even powertrain architecture are unknown. Finally, the tool results quality is evaluated by further developing one of its solutions for passenger car in four different vehicle configurations with the simulation software vemSim and AVL Cruise. The results of the simulations are compared to the solution of the pre-design tool to evaluate the level of fidelity and the deviations in the final result that can appear depending on the final architecture, components characteristics and control strategy.     

Advanced permanent magnet motor drive modeling for automotive application under matlab/simulink environment

This paper proposes an advanced permanent magnet (PM) motor drive modeling for dynamic analysis of automotive control systems with PM motor drives. To enhance the reusability of the proposed PM motor drive model, each component is modeled in an object-oriented manner according to the physical partitioning of a real drive system, and userfriendly and well-organized interfaces are also proposed. These characteristics enable this model to be used as a kind of a programming library. A multi-level modeling strategy is also proposed, which helps make a compromise between model accuracy and simulation speed without structural modification of the system model. The model and modeling strategy developed allow for a comprehensive analysis of each component and dynamic analysis of the total system. System simulation results show the practical effectiveness of the proposed modeling strategy.     

Evaluation of low-temperature diesel combustion regimes with n-Heptane fuel in a constant-volume chamber

The concept of Low Temperature Combustion (LTC) has been advancing rapidly because it may reduce emissions of NOx and soot simultaneously. Various LTC regimes that yield specific emissions have been investigated by a great number of experiments. To accelerate the evaluation of the spray combustion characteristics of LTC, to identify the soot formation threshold in LTC, and to implement the LTC concept in real diesel engines, LTC is modeled and simulated. However, since the physics of LTC is rather complex, it has been a challenge to precisely compute LTC regimes by applying the available diesel combustion models and considering all spatial and temporal characteristics as well as local properties of LTC. In this paper, LTC regimes in a constant-volume chamber with n-Heptane fuel were simulated using the ECFM3Z model implemented in a commercial STAR-CD code. The simulations were performed for different ambient gas O₂ concentrations, ambient gas temperatures and injection pressures. The simulation results showed very good agreement with available experimental data, including similar trends in autoignition and flame evolution. In the selected range of ambient temperatures and O₂ concentrations, soot and NOx emissions were simultaneously reduced.     

GPS资料获取的四川地区应变率演化状态

为了研究汶川5·12地震事件对青藏高原东南缘及四川盆地的应力再分配作用及该区域现今的地震危险性,使用1997-2015年共计355个GPS站点观测资料获取了该区域1997-2008、2009-2011、2011-2013、2013-2015年共计4期独立的速度场,基于规则格网和张力样条插值方法计算了上述速度结果对应的面膨胀率、垂直轴旋转率及最大剪应变率.以2008年汶川Ms8.0级地震为主要节点,以芦山2013年Ms7.0级地震、康定2014年Ms6.3级地震为参考节点,分析了应变率场的时空演化过程及其与地震事件的潜在关联性.研究结果显示:随着汶川震后的时间推移,沿龙门山断裂的3种应变率分布均有减弱趋势,但至今仍未恢复至震前状态,说明该区域的震后回弹受下地壳黏弹性流变物质的弛豫影响较为显著;安宁河-则木河断裂及周边的面压缩率在汶川地震之后有增强趋势,该趋势可能与区域的地震危险性有所关联;安宁河-则木河断裂带及鲜水河断裂北段是未来一段时间该研究区域内应该持续关注的主要地震危险区.      

The implications of increased competition among ports for port policy and management

The increased competition faced by ports is more focused than previously on the performance of logistics systems of which the individual terminals in ports are critical hubs. The changes in competitive conditions raise issues about appropriate public port policies and strategies of port managements. This paper argucs that the port industry should (and is) moving in the direction of more harmonized policies based on economic principles. Port policies based on cost recovery from users of port facilities and services need to be adopted as the international standard. The competitive environment favours considerable local autonomy. Port management, in addition to possible direct responsibility for terminal management, needs to focus on activities with economies of scale or scope. Such activities, which span the requirements of terminals and may even warrant inter-port cooperation, enhance the services available for many port users.