- 著者
- Yoshiki YAMAGIWA Koki TAO Shoji SATO Kiyotoshi OTSUKA Yoji ISHIKAWA
- 出版者
- THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES
- 雑誌
- TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)
- 巻号頁・発行日
- vol.16, no.2, pp.165-171, 2018 (Released:2018-03-04)
- 参考文献数
- 12
The understanding of cable dynamics is one of the most important issues for the design and construction of a space elevator. We propose a new method for constructing the space elevator by simultaneously deploying cables upward and downward from the main space station maintained in GEO and balancing both cables. The analysis is performed using our originally developed cable dynamics model. The model is a two-dimensional lamped mass model. In the model, the tether is modelled by mass points, which are connected to each other by a spring and a damper, and are pulled out per assumed length. In this study, we first analyze the cable dynamics and stress for assumed deployment conditions of the cables. We then obtain the total impulse necessary to keep the main station in GEO and control the cable speed during deployment so that it does not exceed the maximum stress of the cable. The results are also compared with the preceding method for the same conditions. The initial result shows that with the proposed cable-deployment method, the total propellant mass necessary to control cable dynamics while maintaining the station in GEO can be decreased by about one-third compared with that necessary to raise the main station to higher orbit and to control cable dynamics as in the preceding cable-deployment method.
- 著者
- Satoshi MIKAMI Shoji SATO Yoshifumi HOSHIDE Ryuichi SAKAMOTO Naotoshi OKUDA Kimiaki SAITO
- 出版者
- 日本保健物理学会
- 雑誌
- 保健物理 (ISSN:03676110)
- 巻号頁・発行日
- vol.50, no.3, pp.182-188, 2015 (Released:2016-02-06)
- 参考文献数
- 12
- 被引用文献数
- 13
Intercomparison of in situ gamma spectrometry was organized at a site contaminated by the radioactive fallout that originated from the Fukushima Dai-ichi Nuclear Power Plant accident. This intercomparison was conducted by eight teams from four different institutions, which have contributed to the government-led project to construct distribution maps of radionuclides deposited on the ground soil. The resultant 134Cs and 137Cs inventories evaluated by the participants agreed within 6% of the coefficient of variation, after correction for inhomogeneous distribution of the dose rate in air. The evaluated 40K inventories agreed within 4% of the coefficient of variation. The authors estimated that these results were in good agreement for creating distribution maps of the radionuclide inventory in the ground soil.