TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, SPACE TECHNOLOGY JAPAN
Online ISSN : 1347-3840
ISSN-L : 1347-3840
Volume 1
Displaying 1-2 of 2 articles from this issue
  • Toshiaki Iwata, Yoichi Motomura, Kazuo Machida
    Article type: Technical Paper
    Subject area: Space System and Technology
    2003 Volume 1 Pages 1-8
    Published: 2003
    Released on J-STAGE: April 17, 2003
    JOURNAL FREE ACCESS
    A knowledge-based satellite malfunction diagnosis method that shows much promise for future applications is introduced. There are two approaches for diagnosing satellites: the sensor-based approach and knowledge-based approach. The former approach starts from the detection of sensor signals, and infers the malfunction. In contrast, the latter approach starts from the background of the malfunction origin, compares the forecasted satellite state with the observed state, and infers the malfunction. In this study, we propose a new knowledge-based approach that utilizes a database of past malfunction data. First, we compiled 95 malfunction cases related to 54 satellites. Then, the malfunctions were categorized according to the phenomenon, cause, and background among others. Next, we analyzed the categories and found specific properties. We then used a model construction algorithm, Quinlan's C5.0, for the decision tree. Finally, the construction of Bayesian networks is helpful as they execute probabilistic reasoning for malfunction prediction.
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  • Hiroshi Katsurayama, Kimiya Komurasaki, Ai Momozawa, Yoshihiro Arakawa
    Article type: Technical Paper
    Subject area: Aerospace Propulsion
    2003 Volume 1 Pages 9-16
    Published: 2003
    Released on J-STAGE: October 09, 2003
    JOURNAL FREE ACCESS
    Supplementary material
    A preliminary feasibility study of a laser ramjet SSTO has been conducted using engine cycle analysis. Although a large amount of laser energy is lost due to chemically frozen flow at high altitudes, the laser ramjet SSTO was found to be feasible with 100 MW laser power for 100 kg vehicle mass and 1 m2 vehicle cross-section area. Obtained momentum coupling coefficient, Cm, was validated by means of CFD. As a result, the engine cycle analysis was under-estimating Cm. This would be because of the strong unsteady energy input in the actual heating process and the spatially localized pressure on the afterbody.
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