著者

石川 芳男 井上 正史 小宅 康博 山極 芳樹 栗木 恭一

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会誌 (ISSN:00214663)

巻号頁・発行日

vol.41, no.471, pp.205-212, 1993-04-05 (Released:2010-12-16)

参考文献数

9

被引用文献数

1 1

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In coming new space age, we will have frequent trips between the ground and mission orbits by large rockets to realize the large projects such as space stations and solar power satellite systems. In such cases a great deal of rocket effluents should be released in the atomosphere. But, its effects on our environment is still unknown, and therefore various studies on these problems are expected. About such environmental problems, some studies were performed which motivated by so called “ionospheric hole” observed when Skylab-I was launched, May 14, 1973. It was certified by later scientific studies that the phenomenon was caused by the chemical reaction between rocket effluents and ionized particles in the ionosphere, by which the electron density of the ionosphere suddenly decreased to about a half values of that in its normal state in the range of about 1, 000km in radius centering about rocket trajectory and it took about 4 hours to recover. In this study, the results of these fundamental studies are applied to the engineering problem, that is, the numerical simulation of the change in electron density in the ionosphere is carried out in consideration of the diffusion of rocket effluents released along arbitrary trajectory in upper atomosphere and their chemical reactions with the ionospheric constituents.

著者

吉田 洋明 近藤 理良 山口 雄仁 石川 芳男

出版者

一般社団法人 日本機械学会

雑誌

設計工学・システム部門講演会講演論文集

巻号頁・発行日

vol.2003, pp.102-105, 2003

被引用文献数

1 1

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In the present paper, we applied a new optimization method using a stochastic process to the design of the hang glider. As for this problem, not only the hang glider design but also its flight path are optimized at the same time. The method obtains a solution as an expectation (probability average) using stochastic process. The advantages of this method are not to be affected by initial conditions and not to need techniques based on experience. In this optimization problem, the numerical calculation results show that the method has a sufficient performance.

著者

石川 芳男 杉浦 桂 中根 昌克 王丸 哲文

出版者

科学基礎論学会

雑誌

科学基礎論研究 (ISSN:00227668)

巻号頁・発行日

vol.36, no.2, pp.59-66, 2009-03-31 (Released:2017-08-15)

参考文献数

10

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A numerical model (individual-based model) to describe ecosystem dynamics is proposed. The ecosystem is partitioned into the same time and space scale levels and the partitions at different levels are connected through transfer of mass. The partitioned system is expressed as aggregates of three-dimensional cells. Within the cells, nutrient intake, excretion, growth, reproduction, death, and movement of individual organisms are executed in accordance with the model rules. The mass transfer due to metabolic processes of organisms, including energy dissipation (efficiency) is described by difference equations. Movement to neighboring cells occurs through diffusion for substances, and through expansion of habitat range and migration in organisms. This individual-based model was applied to an experimental microecosystem (microcosm) derived from an aquatic ecosystem. This model was demonstrated to be applicable to descriptions from the micro behavior of individuals to macro system formation.