Effects of coolant channels on large-scale Polymer Electrolyte Fuel Cells (PEFCS)

Fully coupled simulations of two-phase transport in Polymer Electrolyte Fuel Cells (PEFCs) and heat transfer in coolant channels are performed in order to investigate the effects of cooling channel configuration on the distributions of temperature and water within PEFCs. When a practical coolant flow rate is applied to large-scale cells for automotive applications, a significant coolant temperature rise is expected from the coolant inlet to the outlet, particularly under high current density operations, creating a significant cell temperature gradient along the flow direction as well. Consequently, a two-phase water profile resulting from evaporation-condensation processes inside PEFCs is also strongly influenced by the cell temperature gradient from the hot coolant inlet toward the cold coolant outlet regions, demonstrating that both temperature and liquid saturation strongly depend on the thermal gradient along the coolant flow path.     

Finite element analysis of rotary blanking: Effects of punch geometries on cutting area and stress distribution

It is essential to develop efficient and cost-effective production methods to achieve or maintain international competitiveness. An innovative production method, such as rotary blanking, enables manufacturers to both reduce expenses and economize production time. However, there are not enough numerical analyses for this process. In this paper, numerical simulations of rotary blanking were performed. After comparing the cutting planes generated by conventional and rotary blanking experimental tests, the cutting areas of two punch geometries were analyzed. The influence of punch geometry on part quality was then investigated through simulations. The procedure for die stress analysis was established and stress distributions of the worksheet and the tools were analyzed.     

论香港地下空间开发的规划、立法与发展经验

 海滨城市香港山多平地少,土地是极为稀少的资源,但山岭地貌和坚硬晶质火成岩岩体很适合开发地下洞室和隧道。20世纪70年代、80年代起,就开始考虑发展地下空间,以满足都市发展的需求。为此,政府开始有计划地进行工程可行性研究,并进行相关的立法工作,为规范地下空间的开发,建立了一套完整的地下空间开发体系。结合工程实例,就香港地下空间开发的研究、规划、开发、管理和立法作简要介绍。     

Judicial Interpretations of Federal Consistency under the Coastal Zone Management Act

The federal consistency provision of the Coastal Zone Management Act (1972) created a new form of interaction between federal and state governments. The implementation of this provision has significant ramifications for coastal management and intergovernmental cooperation in the United States. Past studies have focused on the provision's implementation patterns among U.S. coastal states and federal-state disputes mediated by the Secretary of Commerce. This supplemental article examines judicial interpretations of the federal consistency provision over the past two decades in relation to major issues deliberated by Congress at the time of enactment. Recent changes in the provision, as well as those unresolved issues likely to resurface in future litigation, are also discussed. Seemingly, coastal land use authority and offshore energy exploration remain the most contentious issues surrounding the federal consistency provision.     

The use of GIS and relational database management systems to improve the scheduling operations of paratransit

The scheduling operations of many paratransit agencies in the United States are undertaken manually. Those customers who are eligible to travel call in their requests the day before the trip is needed. As the trip requests are received, they are entered into a list of unscheduled trips. In order to schedule these trips, the scheduler must first determine the number of drivers and shuttle buses that are available as well as the time of availability of each. The scheduler must then try to match the rides that are in “similar” areas around the “same” time to place together on the driver's schedule. As new trip requests are made, the schedulers must adjust the trips that are already scheduled to try and schedule as many trips as possible in the most efficient way.

By developing a system that would improve the scheduling system operations of, in this case, DART (Delaware Administration for Regional Transit) First State Paratransit, customers can expect to receive better service that will improve their ability to travel throughout the community. Some devices that could also improve the operations of paratransit agencies are described in this paper, such as satellite‐based Global Positioning System (GPS), radio communication systems, mobile computers, radio frequency‐based data communication systems, internet web pages, automated paratransit information systems, and card‐based data storage and transfer media. However, because paratransit systems are difficult to operate cost‐efficiently, the optimum and most cost‐efficient device must be selected. The system chosen for DART First State Paratransit includes the use of a relational database management system (RDMS) and a transportation Geographic Information System (GIS). RDMS keeps track of the database information as well as the scheduled trips and the GIS is ideal for analyzing both geographic and temporal data. This system is shown to be superior to the manual system.     

Introducing change to transportation and energy systems: the case of alcohol fuels

This paper describes the application of optimization techniques to the problems of garage location and bus routing. The technique employed involves the decomposition of a garage location and bus routing model into two submodels. Solutions for the garage location and bus routing submodels are combined iteratively to find an optimal solution for the overall optimization model. Significant cost savings realizable for the Transit Authority of River City (Louisville, Kentucky) were calculated by implementing the results.     

Short‐term traffic forecasting: Overview of objectives and methods

In the last two decades, the growing need for short‐term prediction of traffic parameters embedded in a real‐time intelligent transportation systems environment has led to the development of a vast number of forecasting algorithms. Despite this, there is still not a clear view about the various requirements involved in modelling. This field of research was examined by disaggregating the process of developing short‐term traffic forecasting algorithms into three essential clusters: the determination of the scope, the conceptual process of specifying the output and the process of modelling, which includes several decisions concerning the selection of the proper methodological approach, the type of input and output data used, and the quality of the data. A critical discussion clarifies several interactions between the above and results in a logical flow that can be used as a framework for developing short‐term traffic forecasting models.     

Vehicular pollution prediction modelling: a review of highway dispersion models

Air quality modelling plays an important role in formulating air pollution control and management strategies by providing guidelines for better and more efficient air quality planning. Several line source models, mostly Gaussian‐based, have been suggested to predict pollutant concentrations near highways/roads. These models, despite several assumptions and limitations, are used throughout the world, including in India, to carry out air pollution prediction analysis due to vehicular traffic near roads/highways. These models are being continuously upgraded and modified based on field experiments, and numerical and physical modelling results. An effort has been made in the present paper to review briefly the philosophy and basic features of most of the commonly used highway dispersion models. The paper also discusses various theories and techniques that led to the development and modification of these models along with the statistical analysis tools to evaluate the performance of these models. An attempt has also been made to summarize briefly the various line source models currently used in India and to highlight the difficulties being faced while using them in an Indian context.     

Rail policy and performance in Australia

This paper presents a brief review of rail policy and the performance of the rail system in Australia, and draws some comparisons with the rail systems of Western Europe. Australian railways present a somewhat paradoxical mixture of booming traffic with severe financial problems, poor productivity and — in some cases — outdated equipment. The competitive environment they face varies from state to state both in the freedom accorded to road competition and the degree to which the railways themselves are permitted to take decisions on a commercial basis. Whilst some railways in Australia — notably Westrail — have virtually completed the transition from a government department to a commercial enterprise, others have only just begun.