2019 Fiscal Year Final Research Report
Developing the method of measuring thickness and size distribution of mud accumulated on bottom of water by broadband ultrasonic wave
| Project/Area Number |
17K06625
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Civil and environmental engineering
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| Research Institution | National Institute of Technology, Toyota College |
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Principal Investigator |
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Keywords | 超音波 / 底泥 / 粒径分布 |
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| Outline of Final Research Achievements |
The goal of our research during this research period is developing the novel methodology to measure the thickness and characteristics of accumulated bottom sediment in the inland water body. The relationship between the particulate size and the power spectrum of the ultrasonic echo was apparent in a laboratory experiment. The thickness of the sediment, accumulated single layer or double layer, was allowed to measure in a 2% error.
The peak of the power spectrum relies on the sediment particle size to measure the thickness and characteristics of sediment mud in a field, which is the middle size of a water body in a park. This result represents mud particle size estimates from the ultrasonic echo and power spectrum without directly measuring methodology.
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| Free Research Field |
土木環境工学
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| Academic Significance and Societal Importance of the Research Achievements |
従来狭帯域の連続波ではなく，広帯域のパルス波を用いた広範囲のエコー測定で，底質厚の測定と粒径特性を明らかにすることができた。本手法によって底泥質と厚の情報が同時に推定できる可能性を示し，これは浄水場や下水処理場など，水底までの距離が明らかな場所での底泥推定に適用が可能である。
また屋外実験でも底質厚の測定が相対誤差3%以内であることが明らかとなったことから，底泥の媒質ごとの超音波速度が分かれば，水深が分からなくても底泥厚を算出することが確認できた。この基礎実験結果を発展させることにより，超音波により湖沼などの底質厚および粒径特性を安価で短時間に，そして広域で把握する手法の足掛かりができた。
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