著者

井上 裕策 岩井原 瑞穂

出版者

九州大学

雑誌

九州大学大学院総合理工学研究科報告 (ISSN:03881717)

巻号頁・発行日

vol.17, no.3, pp.381-388, 1995

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This paper proposes a method of representing relations implicitly using binary decision diagrams (BDD), which are data structures to represent logic functions compactly, and are widely used in computer-aided design (CAD)area We consider utilization of BDD for query processing in deductive databases. In this paper, we show two methods, called linear encoding and logarithmic encoding, to represent relations implicitly using BDDs. We compared the performances of these encodings with the traditional evaluation based on hash joins, and the proposed methods are faster than the hash-join-based methods over transitive closure queries on linear graphs and dense random graphs.

著者

上広 勝信 饒 燕飛 福田 研二

出版者

九州大学

雑誌

九州大学大学院総合理工学研究科報告 (ISSN:03881717)

巻号頁・発行日

vol.17, no.2, pp.245-252, 1995

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An analytical model is proposed to study regional instabilities in parallel boiling channels with the voidreactivity feedback. The model takes into consideration the effect of interaction between channels with different void fraction change by modeling the diffusion of neutrons. Linear stability analysis in the frequency domain is performed to investigate dominant factors of unstable oscillation mode. In the case of 2 channels, two stability boundaries are found to exist on the stability map, one for the in-phase and the other for the out-of-phase mode instabilities respectively. It is found that the interaction between channels affects the out-of-phase mode instability. For a certain range of the void-reactivity coefficient, the void-reactivity feedback loop is found to be unstable in a certain region on the stability map, which has an effect on the stability of the in-phase mode stability.

著者

中川 清 福田 研二 藤本 登

出版者

九州大学

雑誌

九州大学大学院総合理工学研究科報告 (ISSN:03881717)

巻号頁・発行日

vol.19, no.3, pp.309-315, 1997

被引用文献数

1

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This study has been carried out to probe into the availability of using solar power generation as a substitutive power system for the fossil fuel in Japan. The available space the solar cell array could be installed is 10% for the plottage of major buildings, 0.5~2% for the flat land and a certain percentage for the appended facilities for road, etc. The generation capacity of the solar cell is assumed to be 100 W/m2 at peak time (the average value is 1/10).The generating power calculated from the conditions above is about 250GWp and nearly 75% of that is from the building plottage, and the available space for array installation is close to 0.66% of the gross land area. Also, based on the above estimate, the generating power is expected 286 billion kWh a year, which is about 30% of the total power generated (964 billion kWh in 1994), that is about 5% of the total power consumed (5.9trillion kWh in l994).

出版者

九州大学

雑誌

九州大学大学院総合理工学研究科報告 (ISSN:03881717)

巻号頁・発行日

vol.19, no.2, pp.227-294, 1997