日本指出信号系统发展的另一途径

当欧洲正朝着ERTMS 3级缓慢前进的时候，东日本铁路（JR East）已经测试了与其相当的ATACS，正朝配备这个先进的信号系统快步前进。基于无线的移动闭塞信号系统的好处已经论证多年了，但直到现在才证明了要提供一个强有力的安全系统从技术需要上广泛实现基于无线的移动闭塞信号系统。     

Short sleep duration,sleep disorders,and traffic accidents

Sleepiness is an important factor in traffic accidents caused by human error. The purpose of this paper is to review a number of studies conducted over the years regarding the effect of the lack of sleep on the incidence of traffic accidents as well as the individual effects of various sleep disorders on accidents. In addition, we discuss recent advances in methods of detecting sleepiness and strategies for preventing traffic accident by using these methods.     

Dispersion of spilled oil by a cavitating jet at sea

This article presents the possibility of using a high-speed water jet for the dispersion of spilled oil at sea. Laboratory experiments showed that a high-speed water jet is very effective in dispersing heavy oil. Two methods were examined and compared using freshwater. The first method was to disperse an oil layer on the water surface using a cavitating jet ejected upward at an angle of 45°. A target plate was placed at the interface of the water and oil layer to enhance the collapse of cavitating bubbles. The second method was to eject a high-speed water jet vertically downward from the air. A guide plate with a guide hole was placed under the oil layer with no target plate as such. The second method showed an improved dispersion ability and thus its effectiveness was examined using an oil layer on seawater. The dispersion of oil was better in seawater than in freshwater, probably because seawater contains natural surfactants.     

Onboard monitoring of fatigue damage rates in the hull girder

Most new advanced ships have extensive data collection systems to be used for continuous monitoring of engine and hull performance, for voyage performance evaluation etc. Such systems could be expanded to include also procedures for stress monitoring and for decision support, where the most critical wave-induced ship extreme responses and fatigue damage accumulation can be estimated for hypothetical changes in ship course and speed in the automatically estimated wave environment.The aim of this paper is to outline a calculation procedure for fatigue damage rate prediction in hull girders taking into account whipping stresses. It is conceptually shown how such a method, which integrates onboard estimation of sea states, can be used to deduce decision support with respect to the accumulated fatigue damage in the hull girder.The paper firstly presents a set of measured full-scale wave-induced stress ranges in a container ship, where the associated fatigue damage rates calculated from a combination of the rain-flow counting method and the Palmgren-Miner damage rule are compared with damage predictions obtained from a computationally much faster frequency fatigue analysis using a spectral method. This analysis verifies the applied multi-modal spectral analysis procedure for fatigue estimation for cases where hull girder flexibility plays a role.To obtain an automated prediction method for the fatigue damage rates it is in the second part of the paper shown how a combination of the full-scale onboard acceleration and stress measurements can be used to calculate sea state parameters. These calculated environmental data are verified by a comparison to hindcast data.In the third part of the paper the full-scale fatigue stress ranges are compared to results from an analytical design oriented calculation procedure for flexible ship hulls in short-term estimated sea states.Altogether, it is conceptually shown that by a combination of the onboard estimated sea state parameters with the described analytical fatigue damage prediction procedure a method can be established for real-time onboard decision support which includes estimates of fatigue damage rates.     

Development of a computer-aided process planning system based on a knowledge base

 Process planning for a hull structure defines the assembly sequence of the hull block. Although this activity is very important because the working strategy defines the production costs, to date it has been done manually. To raise the efficiency of this process, we developed a practical computer-aided process planning system. It has been developed using deliverables obtained from advanced computer integrated manufacturing system (CIM; ACIM) for shipbuilding projects sponsored by the Ship and Ocean Foundation (SOF). The system has a knowledge base which contains the know-how of skilled designers as well as design practices, and allows the assembly sequence of hull parts and intermediate products to be defined automatically. The system has been integrated with the shipyard CAD system MATES, and put to practical use. Received: August 19, 2002 / Accepted: November 25, 2002 Address correspondence to: Y. Sasaki (yuuichi_sasaki@mhi.co.jp) Updated from the Japanese original, which won the 2002 SNAJ prize (J Soc Nav Archit Jpn 2001;189:309–315)     

A new weather-routing system that accounts for ship stability based on a real-coded genetic algorithm

The operation schedule of an oceangoing vessel can be influenced by wave or wind disturbances, and is therefore weather routed. The weather-routing problem is considered to be a multimodal function problem. Therefore, in the present research, the real-coded genetic algorithm technique (an evolutionary calculation technique) is applied to globally search for the optimum route. Additionally, to avoid maritime accidents due to parametric rolling, this route optimization method takes into account the risk of parametric rolling as one of its objective functions. Numerical verification is carried out for three kinds of objective functions with different weight ratios between fuel efficiency and ship safety in parametric rolling. As a result, it is numerically confirmed that the relation between economics and ship safety is a trade-off, and the safer route is not necessarily the most economical. Considering its robustness, the proposed method appears to be a powerful practical tool by choosing the most appropriate weights for economics and ship safety.