Osamu Muragishi

Concept of inflatable elements supported by truss structure for reflector application

Abstract A concept of modularized inflatable space structure, which is composed of inflatable elements supported by a truss structure for high-precision reflector missions in relatively near future, is proposed to avoid some difficulties of conventional inflatable concept, such as the lack of inside hard points, and the precisely accurate manufacturing process. Some fundamental characteristics for surface accuracy of inflatable elements are studied, appropriate truss back-up structure is investigated, and the relevant prelimimary test results are described. Some aspects of the application of the concept to space VLBI antenna are also introduced.

A study of a fatigue management system for long LNG carriers using a new fatigue damage sensor

Abstract A pro-active safety management system for ship structures that quantifies the aging effect such as by fatigue and corrosion on the ships structural integrity is proposed as a new approach to the ships structural surveys that have conventionally been made according to a more passive management system. Some of the authors have developed a compact fatigue damage sensor that can detect accumulated fatigue damage in welded structures by attachment to the member and inspection after a certain period. The authors have applied this sensor to the hull structures of an LNG carrier for experimental purposes, ascertained its long-term durability under the severe environment to which the ship was exposed and obtained quantitative data on the accumulated fatigue damage. In this paper, the authors propose a fatigue management system using this sensor called the Hull Aging Management System and propose it as a pro-active safety management system for LNG carrier hull structural aging and introduce a method to improve the accuracy of accumulated fatigue damage detection by using this sensor.

Two-phase flow behavior in a spiral tube under microgravity

Abstract Experiments were performed to observe the flow patterns and the behavior of a two-phase (liquid/gas) flow in a spiral tube under microgravity. The liquids used were ethyl alcohol and R113. The microgravity environment was performed using a 10-m-class drop tower, which can maintain a gravity level of 10 −2 g for about 1 s. Photographs of the flow behavior were taken by a micro CCD camera and transmitted to a video cassette recorder. Preliminary models to explain the observed flow pattern map are evolved.