Systems-on-chip approach for real-time simulation of wheel–rail contact laws

This paper presents the development of a systems-on-chip approach to speed up the simulation of wheel–rail contact laws, which can be used to reduce the requirement for high-performance computers and enable simulation in real time for the use of hardware-in-loop for experimental studies of the latest vehicle dynamic and control technologies. The wheel–rail contact laws are implemented using a field programmable gate array (FPGA) device with a design that substantially outperforms modern general-purpose PC platforms or fixed architecture digital signal processor devices in terms of processing time, configuration flexibility and cost. In order to utilise the FPGA's parallel-processing capability, the operations in the contact laws algorithms are arranged in a parallel manner and multi-contact patches are tackled simultaneously in the design. The interface between the FPGA device and the host PC is achieved by using a high-throughput and low-latency Ethernet link. The development is based on FASTSIM algorithms, although the design can be adapted and expanded for even more computationally demanding tasks.     

Ranking of factors contributing to higher performance in the ocean transportation industry: a multi-attribute utility theory approach

Ocean transportation has been mainly studied from an economic and strategic point of view. This paper adopts an operations management approach aiming at the identification of the value-adding attributes that characterize the ocean transportation industry. This is achieved by using Johansson et al.'s 1 four value metrics—service, quality, cost, time—which are used for the identification of the contribution that different factors make to the total created value. In this paper, multi-attribute utility theory (MAUT) has been used to measure and compare the value of different processes of various sectors of the ocean transportation industry. The application of MAUT methodology is illustrated with an example from the four sectors of the industry: liner, dry bulk, liquid bulk and specialized. Results suggest that there is strong emphasis placed by ocean transportation companies on quality and that there is differentiating importance put on service and cost by different sectors. Time is seen as the lowest value contributor by all four sectors of the surveyed companies.     

基于遗传算法的盾构隧道管片接头刚度反演研究北大核心CSCD

梁-弹簧模型在管片衬砌结构计算中应用较广泛,目前接头刚度取值方法主要有模型试验法及经验取值法,模型试验法耗时长、成本高昂,而依据经验取值难免存在一定主观性。鉴于此,利用C++编程语言,基于遗传算法开发了盾构隧道管片结构位移反分析程序,首先通过弹性模量值反演算例,得出反演值与理论值误差为1.4%,验证了算法和程序的可行性。利用程序将反演接头刚度值与实际设计案例管片接头刚度值进行对比,反演计算结果表明:正弯矩下管片环向接头转动刚度值反演误差为2.6%,负弯矩下管片环向接头转动刚度值反演误差为4.3%。     

Ranking of factors contributing to higher performance in the ocean transportation industry: a multi-attribute utility theory approach

The North American Free Trade Agreement (NAFTA) signed by Canada, the U.S.A. and Mexico and which came into effect on 1 January 1994, is a significant move towards further integration of the North American economies. This paper examines the likely impact of NAFTA on Canadian ports. Three channels of impact are identified. First, there are direct impacts on trade flows between Canada and its North American trading partners. In this regard we find that ports do not typically handle the types of products that are likely to be affected by NAFTA, and so the direct impacts may be minimal. Second, and more significantly, port catchment areas are likely to undergo substantial changes as they respond to a more competitive environment within the free trade area. Third, the transportation sector has itself been included in NAFTA, and Canadian ports will face increased competition from land based transportation modes. We conclude that ports in Canada must learn to work more consciously as agents of regional economic development.