IEC列车通信网络

国际电工委员会（ＩＥＣ）和国际铁路联盟（ＵＩＣ）为铁路车辆之间和车辆内互相联接的可编程设备制定了一项标准——《列车通信网络》（ＴＣＮ），其目的是有利于铁路运用部门、装配厂和设备供应商实现世界范围的车辆间的相互操作和插入式设备的联接。文章介绍了ＴＣＮ的体系结构，包括绞线式列车总线（ＷＴＢ）和多功能车辆总线（ＭＶＢ）的功能、技术参数、公共协议及网络管理，并对ＴＣＮ原型的开发、试验验证情况和标准草案工作进程作了简要的说明。     

柴油机气缸盖机械变形和应力的精确三维分析

本文在分析了国内外大量气缸盖结构分析算例特点的基础上,对16V240ZJ柴油机气缸盖的机械应力用三维有限元法在微机上进行了比较全面细致的计算,在计算模型中,对气缸盖各部分结构都不作替代简化;在边界条件的处理方面,计入了气缸套的弹性,并与刚性支承边界条件计算结果进行了比较,计算求得的位移和应力分布规律与实测完全一致,最大位移误差6.5％,最大压应力误差7.4％。     

Benthic megafauna communities under the influence of the South Atlantic Central Water intrusion onto the Brazilian SE shelf: A comparison between an upwelling and a non-upwelling ecosystem

The structure and dynamics of the benthic invertebrate megafauna of the Southeastern Brazilian shelf were studied over a 2-year period. Two regions presenting different oceanographic conditions, Ubatuba-SP and Cabo Frio-RJ were compared in terms of biomass, density of organisms and species richness. Two to three 30-min tows were undertaken at each of the stations, located at 40 and 100 m isobath, in a normal transect offshore of both regions. Faunal distributional patterns correlated with water mass dynamics, depth and sediment parameters. In the Cabo Frio region, subjected to a Ekman-driven seasonal coastal upwelling, the impact of the South Atlantic Central Water (SACW) on the inner shelf leads to a change in the benthic communities, with a high dominance of top carnivores such as the crab Portunus spinicarpus and the sea-star Astropecten brasiliensis, which accounted for the larger part of the total biomass. Distinct species associations were found in each of the two regions and the total biomass at Cabo Frio inner shelf was almost twice that of Ubatuba during the 2002 summer, when a marked upwelling was verified. The relationship between megabenthic biomass and input of organic matter to the sea floor during upwelling events is discussed.     

Prediction of ship brittle fracture casualty rates by a probabilistic method

It has been proposed that grade A should be replaced with a tougher steel for ship construction. This recommendation is not supported by casualty statistics. Brittle fractures have decreased from once every 10 ship years at the time of the Liberty ships, to once every 100 ship years in the 1950s, and now stand at around once every 10,000 ship years. The authors have developed a probabilistic fracture mechanics approach indexed to the Charpy 27 Joule temperature, T_27J. This is used here to analyse the Liberty ship failures. Comparison with a databank of T_27J values for grade A steel spanning 1920 to 1995 suggests that the Liberty ship steel was unusually brittle. The probability analysis shows good agreement between predicted and observed fracture casualty rates for the Liberty ships and helps explain why brittle fractures are now uncommon in grade A steel ships.     

MANTO — a research project of telecommunication applications for the future information society

The impact of new technologies has been mostly under-estimated in the past and, as a result, the transitions from one era to another have occurred more or less by chance. The MANTO research project is intended to avoid mischances. So it indicates potential developments in the telecommunications sector and, in particular, investigates their effects upon transport and settlement and also upon society, the economy and the environment. Nevertheless, MANTO does not merely take a look at the future, like the Greek oracle from whom it takes its name; by means of concrete recommendations, MANTO is intended to provide persons in responsible positions with a tool with which they can consciously organise that future. Risky developments are to be precluded in advance while desirable consequences are to be promoted. Explanation of the used term: MANTO was the daughter of the famous prophet Teiresios of Theben and a seer herself too. As a (German) abbreviation MANTO also stands for: human being (Mensch), offer (Angebot) and needs (Nachfrage) for transportation and telecommunication (Transport und Telekommunikation), considering economy and ecology (Oekonomie und Oekologie).     

Educational technology: Enhancing port training

Continued improvements in educational technologies using CD-ROM and the Internet can enhance student learning in both a face-to-face mode and delivery at a distance. This paper considers the development and use of enhanced educational technologies for port training and education, both within the classroom and at a distance.     

Estimation of capacity utilization in world shipping

The surplus of tonnage which has characterized the shipping industry for over a decade has severely affected profitability and investment opportunities in the industry. This has prompted various schemes to reduce the surplus. A proper assessment of the size of the surplus is an essential requirement for sound policy measures. This paper, which focuses on the tanker sector, examines selected methods used to compute surplus tanker tonnage and proposes other methods. It observes that methods currently used give estimates of surplus tonnage which are basically identical to those obtained by using alternative methods. It concludes that while from 1984 the surplus tanker tonnage has been declining, from 1986 the decline has been rather small and the volume of the surplus is likely to stabilize in the next few years at more or less current levels. However, the paper points out conceptual and practical problems of determining the appropriate base periods or base operating conditions upon which surplus tonnage may be computed.     

The Bathside Bay story

In this article the author considers whether an opportunity to develop harbour facilities at a strategically located site in Harwich Harbour on the east coast of England may have been missed in the 1960s and 1970s. The complications of divided ownership and powers to develop the site are explained; and successive attempts to obtain Government approval for harbour development under section 9 of the Harbours Act 1964 (since repealed) are described. The effective operation of that control in this case, influenced at one stage by political considerations, is questioned.     

电气化铁路传动技术100年的发展(二)

在直流电气化铁路上,一开始就较好地掌握了传动技术,但在交流电气化铁路上,几十年来传动技术要求供电电源的频率低于地方电网的频率.进一步发展传动技术时只有使用电力电子技术才可减小受电网支配的影响.今天用GTO和IGBT电力电子元件和微机控制技术,能在所有供电电网下使用交流传动技术.