车体下部噪声的吸声降噪对策

降低高速列车产生的噪声,必须降低车体下部噪声。本文对用吸声板降低车体下部噪声的措施作了介绍,对吸声材料的性能进行了评价,对贴附在实际列车上的吸声板的最佳面积进行了阐述。     

高速列车机车车辆的牵引性能

在采用感应电动机作为牵引电动机时,牵引与电制动特性不仅取决于感应电动机的参数,还取决于逆变器的性能。由于逆变器无法将直流转换为一个理想的交流值,必须考虑谐波的产生以及类似问题。分析认为高速列车最显著的变化是彻底减小了运行阻力。500系新干线列车的运行阻力约是0系的一半。最新的新干线列车以300km·h-1速度运行,却比0系新干线列车甚至其他国家的高速列车耗能少。     

日本铁路隧道病害和运维管理现状及对我国隧道运维技术发展的建议

日本铁路隧道（包括城市轨道交通）经过100余年的发展，产生了隧道老龄化严重、剥落掉块、开裂、劣化以及渗漏水等病害。通过调研日本铁路隧道建设情况、性能要求、病害类型与原因，得出日本铁路隧道约40%的病害与设计施工有关，27%的病害与运行环境有关，23%的病害与所用材料有关，10%的病害与外力变化有关。介绍日本铁路隧道维护管理体系（隧道检查、健康诊断、措施对策、记录存档）、自动检测技术和智能化技术等新技术的发展应用及存在的问题（相同条件下同类隧道的运维无法统一；自动化检测技术因成本过高或未达到标准要求，只能作为辅助检查手段服务于部分隧道；很多信息因保密无法实现资源共享；运维技术人员、隧道专业人才不足及人才老龄化严重等）。指出这些问题不仅阻碍了运维技术的高质量发展，也影响了整个运维成本和质量。针对我国隧道运维技术的发展，提出以降低隧道设施的全生命周期成本与延长服役寿命为目标，构建基于结构性能与成本的“预测型”运维体系，建议发展一体化运维技术、研发快速维修加固技术、开发智慧运维管理系统等，通过多学科融合交叉，构建系统性的运维管理体系。     

Collapse strength of hatch cover of bulk carrier subjected to lateral pressure load

A series of elastoplastic large deflection FEM analyses has been performed on hatch covers of bulk carriers subjected to lateral load. Two types of hatch covers are considered which are the folding type and the side-sliding type. For the folding-type cover, one size is considered which is for Handy size bulk carrier, whilst for the side-sliding-type cover, two sizes are considered which are for Panamax and Cape size bulk carriers. For each type, two hatch covers are selected which are designed in accordance with the old ICLL rule and new IACS rule, respectively. Calculated collapse strengths are compared with individual design loads, and a strength assessment is performed. On the basis of collapse behaviour observed in FEM analyses, a simple method is proposed to evaluate the collapse strength of a hatch cover subjected to lateral load. It is confirmed that the collapse strength is accurately predicted by the proposed method.     

Analysis of the accident of the MVNakhodka. Part 2. Estimation of structural strength

In the early morning of January 2, 1997, a Russian tanker, the MVNakhodka, broke in two in the Sea of Japan. The fore part of the vessel drifted and was stranded on the coast of Japan, and the aft part sank. The coast of Japan was seriously polluted by spilled heavy oil. Following this disaster, the Japanese Government established a Committee for the Investigation of the Causes of the Casualty of theNakhodka. This paper deals with the structural strength of MVNakhodka at the time of the accident. First the structural characteristics of theNakhodka are described, and the reduction in thickness of the structural members are estimated based on the data measured on the fore part of the vessel which drifted ashose. Then the ultimate longitudinal strength of the hull girder at the time of the accident is evaluated by applying Smith's method, and the possibility of break-up collapse due to excess loads is discussed. The mechanism of fracture at the bottom plate is also discussed based on the observed fracture surfuce of the cross section. Finally an FEM (finite element method) simulation of the break-up of the hull girder is performed. It is shown that buckling/plastic collapse took place at the deck plate near Fr.153, which was followed by the successive buckling collapse of the side shell plate of the hull girder. Right after the collapse of the deck structure, the bottom plate fractured just in front of the transverse bulkhead at Fr.153. This article is based on an article that appeared in Japanese in the Journal of the Society of Naval Architects of Japan, vol. 183 (1998).     

深切缅怀王梦恕院士

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