An Operational Research Approach to Shipping

This paper shows how the Operational Research approach can be used in the shipping industry to obtain effective savings. The approach is by way of a recent study to determine an optimal drydock policy in which the principal criterion was to minimize the total cost of operation. Additional areas, indicating the range of studies carried out in the marine field, are also mentioned.     

基于半导体开关的100kV脉冲功率系统

介绍了一种基于脉冲功率晶闸管的100 kV高压脉冲功率系统,详细说明了系统整体设计方案,同时描述了关键电路的设计原理及系统布局时所要注意的关键点。试验证明,该系统可靠性高、实用性强。     

Car availability change in England and Wales 1971–1981

The aggregate dynamics of car ownership have overshadowed the dynamics of car ownership and availability at the personal and household level. These dynamics have only recently been investigated in more depth. This paper contributes to this work by probing a special data source, theLongitudinal Study (LS) produced by the Office of Population Censuses and Surveys, for the changes in household car availability.The paper describes the LS and explains its special format, as a Census-based ~1% sample of the population of England and Wales.The analysis focuses on the car availability dynamics of a number of groups defined by changes in their life cycle position. Special attention is given to those households where the LS member remains a dependent child throughout the study period.The results show that all studied household types increase and decrease their car holdings, but that there are patterns in this process, which vary from group to group. In particular, the size of the previous car fleet has a different influence on the current fleet size from life cycle group to life cycle group.The paper argues in its conclusion to incorporate these differentials into the further work on car ownership and car ownership change.The work reported here was performed, while the author was a staff member of the Centre for Transport Studies, Imperial College, London.     

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近年来，一些大城市通过修建大量的道路来缓解交通拥堵的压力，但这种做法却导致更多的车辆使用道路，从而加剧了交通拥堵，造成空气质量下降，资源浪费严重。为解决这些问题，一些城市已经开始或者计划构建以轨道交通主体，轻轨交通或者其他交通方式为补充的交通体系，以增强路网的流动性和可达性。本文从城市流动性和可持续发展的角度，对已有的和新型的轻型交通系统做综述。旨在为交通规划人员进行可持续发展交通运输系统的规划等工作提供参考。     

MODULATION OF A δ－AND C－FIBER EVOKED RESPONSES OF NOCICEPTIVE NEURONS IN THE SUPERFICIAL AND THE DEEPER DORSAL HORN OF THE ME

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NOVEL PHOSPHORYLATION SITES OF EUKARYOTIC INITIATION FACTOR－4E AND EVIDENCE THAT PHOSPHORYLATION STABILIZES INTERACTIONS OF T

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OPIOIDS MODULATE NMDA－EVOKED RESPONSES OF NEURONS IN THE SUPERFICIAL AND THE DEEPER DORSAL HORN OF THE MEDULLA

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Experimental investigations on the damping effect due to passengers on flexural vibrations of railway vehicle carbody and basic studies on the mimicry of the effect with simple substitutions

The effect of passengers on a railway vehicle is usually considered as additional mass in designing a carbody. However, previous studies by means of stationary excitation tests or running tests using actual vehicles indicate that passengers behave not as mass but as damping. In this paper, the authors examined the passengers' damping effect under controlled excitation conditions on a roller rig through a series of excitation tests using a commuter-type vehicle. Large and multi-modal reductions of flexural vibrations of the carbody were observed when passengers existed. Influences of the number of passengers, distributions and postures of passengers were investigated. The authors also tried to mimic the damping effect by passengers using flexible tanks filled with fluids. Three kinds of fluids which have different viscosities have been tested. As a result of the excitation tests, good vibration reduction effects were observed by applying those tanks, and it has been found that the flexible tanks filled with fluids bring about vibration reduction effect (including multi-modal reduction) which is equal to or rather better than the case of similar mass of passengers in the carbody; the difference of viscosity gave little affect on the damping abilities. From these measurement results, a possibility of realising effective damping devices against flexural vibrations of railway vehicle carbodies representing passengers damping effect, in a simple, economical and environmental friendly way, has been demonstrated.     

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钢结构桥梁形式多样,优点突出,在世界各地应用广泛,为了推进中国钢结构桥梁的建设,促进中国钢结构桥梁抗火防灾研究领域的全面发展,加快钢结构桥梁抗火防灾技术的研究,加强钢结构桥梁抵抗火灾的能力,提升管理部门应对钢结构桥梁遭遇火灾时的应急水平,对钢结构桥梁抗火防灾的研究现状与亟待解决的问题进行了总结。研究了国内外钢结构桥梁火灾发生时的场景以及钢结构桥梁遭遇火灾时的破坏形态,分析了钢结构桥梁火灾发生时的特点,强调了油罐车火灾对钢结构桥梁安全性能的严重威胁,给出了钢结构桥梁抗火防灾的关键技术。继而,对其抗火研究存在的问题进行了梳理,包括钢结构桥梁所用材料的高温特性,复杂环境下钢结构桥梁截面的传热机制、钢-混凝土组合梁界面间的高温作用机理、钢结构桥梁火灾行为的数值模拟与智能预测技术、火灾全过程中钢结构桥梁的试验与测试方法、火灾高温下钢结构桥梁的力学行为以及钢结构桥梁抗火研究的工程应用等七大方面给出了钢结构桥梁抗火研究亟待解决的问题和更高的目标。以期对钢结构桥梁抗火防灾方向的技术研究提供全新的视角和基础资料。     

Shape optimization of a torsion beam axle for improving vehicle handling performance

In this study, shape optimization was conducted for a vehicle’s rear suspension torsion beam to improve its dynamic handling performance. To determine the design variables affecting the vehicle roll characteristics, a sensitivity analysis was conducted using the result of a Taguchi experiment with 6 factors in 8 runs. The upper and lower-flange lengths and web thickness of the torsion beam section, as well as the vertical height difference between the inner and outer of torsion beams, were determined as design variables through sensitivity analysis of the opposite wheel travel test for optimization of the torsion beam axle. The Box–Behnken experimental design with 4 factors and 27 runs was performed using the selected design variables and by performing opposite wheel travel analysis according to the experimental design, and the response surface functions of the roll stiffness, roll steer coefficient, roll center height, and mass of the torsion beam were generated. Using these response functions, shape optimization was conducted for the torsion beam of the rear suspension system. Dynamic performance analysis was performed by applying the optimized H-shaped torsion beam to the rear suspension of the vehicle dynamics model, and it was validated that the dynamic response performance of the optimized vehicle was improved.