1996 Fiscal Year Final Research Report Summary
A New Measuring method for effluence gas flux into atmosphere with a laser
| Project/Area Number |
07650496
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
計測・制御工学
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| Research Institution | Okayama University |
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Principal Investigator |
KOGA Ryuji Okayama University, Faculty of Engineering, Professor, 工学部, 教授 (20027147)
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| Co-Investigator(Kenkyū-buntansha) |
KAGAWA Naoki Fukuyama Unversity, Faculty of Engineering, Lecturer, 工学部, 講師 (80258300)
MING Wang Okayama University, Graduate School of Natural Science and Technologies, Assista, 大学院・自然科学研究科, 助手 (60253019)
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| Project Period (FY) |
1995 – 1996
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| Keywords | scintillation / methane gas / infrared absorption spectrum / effluence / DSP / atmospheric concentration flux / lead-salt diode laser / temporal resolution |
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| Research Abstract |
Propagation of laser beam in open atmosphere is heavily suffered from the fluctuation of atmospheric constituent, density and temperature. Quantity of methane gas penetrating through the ground surface is governed by the production rate under the ground as well as by the chemica activity at the ground surface.
This group measured temporal variation of absorption for for the 7 micron meter band laserbeam using a lead-salt diode laser. They there found that the spectra of the absorption signal below 1 Hz correspond to atmosheric methane density, and that beyond 10Hz to the scintillation. In other words, one can measure methane density independent from the scintillation if the absorption line is spectrally scanned within a few milli-seconds. A test equipment was build and outdoor measurement was conducted.
The equipment fully utilize the DSP (Digital Signal Processor) LSI,which allows the systm temporal resolution as short as 4 milli-seconds to spectrally scan a methane absorption line. A clear spectrum of methane was actually measured being not smeared by scintillation, which would not be able to achieve with a scheme that employ a long temporal integration.
This results assures the possibility to further develop an apparatus to measure gas effluence flux into open atmosphere.
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