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摘要：適切な緑地環境の維持管理には，植生に対する環境ストレスの非破壊検出法の開発が急務な技術的課題である。本研究では， 気泡運動モデルを用いて AE(Acoustic Emission)法により検出した植物起源弾性波の周波数特性評価を試みた結果を報告する。水 ストレス条件下では，植物体道管部に発生する気液二相流起源の弾性波が検出される。検討の結果，検出された AE 波の周波数特性 は，Rayleigh-Plesset 方程式より評価された周波数範囲と類似していることが明らかになった。このことから，AE 法により検出さ れた弾性波は，水ストレス条件を定量評価できるものと考えられる。 キーワード：弾性波，AE 法，気泡運動モデル，気液二相流 SUZUKI, Tetsuya, UENO, Yuki and SHIMAMOTO, Yuma: Quantitative evaluation of detected elastic waves generated from plant using bubble motion model Abstract: The optimum management of re-vegetation fields, non-destructive testing method for evaluation of environmental stress of plant is now in urgent demand. In this study, characteristics evaluation of frequency of detected acoustic emission waves generated from plants is going to be performed, applying bubble motion model. In water stressed conditions, elastic waves are emitted from gas-liquid flow in plant vessel. The characteristic of frequency of detected elastic waves by AE is similar to the analytical results by using the Rayleigh-Plesset equation. Thus, the water stress condition in plant is quantitatively evaluated by AE.

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Steel sheet pile materials are primarily used for canal structure construction for irrigation and drainage of agricultural fields in Japan. Recently, accelerated corrosion of steel materials and buckling phenomena in pitting corrosion parts have been detected in in-service steel sheet pile canals. In this study, we focus on the buckling phenomenon of in-service steel sheet pile canals, which is detected by non-contact monitoring using digital image analysis. The buckling phenomenon index is evaluated as the inclination angle of the steel sheet pile due to deformation. As a digital image analysis, Hough transform is applied, which is a figure detection method in digital images, to detect a straight line that describes the distance and angle parameters. The angle parameter corresponds to the inclination angle index of in-service steel sheet pile with a buckling phenomenon. As a result, the maximum difference between the analyzed angles by Hough transform and the measured angles is evaluated as 0.9° after the image rotation correction. The relation of the analyzed angles by Hough transform and the measured angles of the buckling phenomenon is correlated. Therefore, the degradation of steel sheet pile canals is quantitatively evaluated by using digital image analysis with unmanned aerial vehicle monitoring. This study’s significance is non-contact and simple measurement by using a digital image which can reduce a working time and perform quick diagnosis in extensive areas.