Quasisteady theory for the hydrodynamic forces on a circular cylinder undergoing vortex-induced vibration

Vortex-induced vibrations of a rigid circular cylinder were studied by constructing a theory based on a wake oscillator model under quasisteady approximations, thereby evaluating vortex-induced hydrodynamic forces acting on the cylinder. A lock-in limit line representing the boundary for the occurrence of frequency lock-in was also theoretically derived. Hydrodynamic forces in forced oscillation problems estimated by the theory were compared with measured ones. Although some discrepancies were found, particularly in cases with high-frequency oscillations, good agreement was achieved in most cases. Accordingly, we conclude that the present theory captures well real phenomena in the wake downstream of a cylinder subjected to a flow.     

At-sea towing of a Mega-Float unit

A huge floating offshore platform (359m long, 60m wide, and 3m deep) was towed into the Pacific Ocean for a validation experiment for a floating airport. Full-scale measurements of towline tension and the bending strain on the upper-deck were made during towing. The measured bending moment agreed well with numerical calculation without taking the draught and towing speed into consideration.     

Ship inspection support system using a product model

 Recently, the significance of ship inspections has been increasingly recognized because sea pollution and safety problems are occurring more and more frequently. However, current ship inspections rely on the experience of the workers. Therefore, it is difficult to understand, and hence to improve, the state of ship inspections. In this paper, ship inspection is directed into three stages (plan, do, and check), and the configurations of a total system to support ship inspections are discussed. A prototype system for the “plan” and “do” stages is developed. This is realized by organizing the information that relates to inspection, and defining data models for damage and inspection states. Then the proposed system is integrated with a shipbuilding computer integrated manufacturing (CIM) system so that the ship's structural information can be used effectively. In addition, functions to calculate the damage-finding probability, and functions to generate information about damage and the inspection state are introduced. Therefore, in the planning stage, as inspector can execute a virtual ship inspection, and then the damage-finding probability of each hull part and oversight areas are calculated automatically. Further, by carrying this system into an inspection, an inspector can generate damage information and inspection information simply and easily. Some examples of the proposed system are shown at the end of the paper. Received: November 12, 2001 / Accepted: January 30, 2002     

Slamming load on a very large floating structure with shallow draft

The objective of this paper is to estimate the slamming load acting on a pontoon-type very large floating structure with a shallow draft. Experiments were carried out using elastic models with different rigidities in regular waves. The results revealed that the slamming load was strongly influenced by the rigidity of the model. The conditions under which slamming occurs depended on the extent of the bottom emergence and the velocity of the relative wave height at the bow of the model. These results were related to a simple procedure for estimating slamming load.     

基于约束理论的船舶管系加工进度计划系统研究

船舶管系生产是船舶建造的一个重要部分,管系生产的进度情况直接影响着全船的建造计划.该研究结合管加工工厂生产管理中的实际问题,通过引入约束管理理论(TOC),开发了适用于船舶管系生产的进度计划系统.该系统集成了管子制品模型、生产资源模型、生产作业模型以及加工数据库,实现了作业计划和生产进度计划编制的自动化.此外,该文评价了系统在应用中所取得的效果,认为系统在管子生产的进度管理、设备利用率和库存等方面均具有较传统方法更优的表现.     

Erratum to: Development of a Theory of Constraints Based Scheduling System for Ship Piping Production

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Study of a simple sensor for stress history measurements of a structural member using a piezoelectric element

This paper describes a stress sensor using a piezoelectric element which was developed to monitor features of the stress history of a structural member. The sensor is 90 mm long, 60 mm wide, and 25 mm thick. A stress-level meter can turn on and off different colored light-emitting diodes (LED) according to the changes in a stress level. A stress-level cross counter can display the number of cycles which exceeds a specified stress level during a monitoring period. The sensor is bonded onto a structural member using an adhesive agent. In order to see the performance of the prototype sensor, experiments were carried out using a fatigue-testing machine. The sensor was bonded onto a smooth specimen and multiple repeated stresses were applied to that specimen. There were three main findings. (1) The sensor can operate under a stress range from −150 MPa to 150 MPa, and a frequency from 0.05 Hz to 5 Hz. (2) The stress-level meter can turn the lights of the LED on and off accurately under any stress amplitude and frequency. (3) When the stress frequency is 1 Hz or less, the stress-level cross counter can count accurately the number of cycles which exceed the predetermined stress levels. Received: February 25, 2000 / Accepted: April 11, 2000     

日本N700系列高速列车的发展

中日本铁路公司将于明年在东海道新干线上引进新一代的高速列车，这将为铁路建立新的技术标准奠定基础：同时，这也展现了该公司在过去42年里为提高东海道新干线的运输能力做出不懈努力所取得的最新成果。     

基于ITOC的船舶管系生产进度控制系统研究(英文)

Manufacturing of ship piping systems is one of the major production activities in shipbuilding. The schedule of pipe production has an important impact on the master schedule of shipbuilding. In this research, the ITOC concept was introduced to solve the scheduling problems of a piping factory, and an intelligent scheduling system was developed. The system, in which a product model, an operation model, a factory model, and a knowledge database of piping production were integrated, automated the planning process and production scheduling. Details of the above points were discussed. Moreover, an application of the system in a piping factory, which achieved a higher level of performance as measured by tardiness, lead time, and inventory, was demonstrated.     

Efficacy of bus service reorganization utilizing a hub-and-spoke topology and DRT to meet community needs: A case study of Tokigawa town

The purpose of this study is to verify the efficacy of a route/timetable reorganization methodology focused on a hub-and-spoke schedule bus architecture as well as the introduction of demand responsive transport (DRT) in suburban or underpopulated areas in Japan to accommodate local requirements.