今年も残りあとわずかというところでまた素晴らしいニュースが参りました。非破壊検査に関する学術論文誌NDT&E International誌に今年２報目のアクセプトです。
A journal paper entitled 'Investigation of the Effect of a Bend on Pipe Inspection Using Microwave NDT' was accepted by NDT&E International on December 7th, and available online at https://doi.org/10.1016/j.ndteint.2019.102208
論文の内容は、配管の内部にマイクロ波を伝播させることで配管内壁面の広域一括探傷を行う技術に関し、配管の曲がり部の影響を定量的に評価した、というものです。理論解析、数値解析、そして検証実験の結果、曲率半径比がある一定値以上であれば影響は小さく、また局所的である（広域的な評価においては従来の知見が適用できる）ということを明らかにした、という報告です。以前の研究でなんかそうなるような気がするなー/そうなってほしいなーとは思っていたのですが、まさかここまできれいにまとめられるとは思っていませんでした。
The authors of this paper are Guanren Chen, Takuya Katagiri, Haicheng Song, Noritaka Yusa and Hidetoshi Hashizume. The first author Guanren Chen will cook something using the bread machine in the lab 303 for celebration.
One thing I'd like to share here is that Prof. Yusa may have the ability of predicting the future. On December 7th, 23:41, Prof. Yusa firstly posted an announcement that 'the student who have a paper accepted will make something using the bread maker in 303'. And just less than three hours later, the acceptance letter from NDT&E International was sent to me. All facts lead to one conclusion, Prof. Yusa is a prophet and able to predict the future things. Probably his post was the deterministic factor for the paper acceptance.
Abstract
This study investigated the effect of a bend on microwave NDT (non-destructive testing) applied for rapid pipe inspections. The factors affecting the mode conversion of microwaves due to a bend were deducted theoretically and verified through numerical simulation. Both theoretical and numerical results revealed that the mode conversion at a bend was actually determined by the frequency normalized by the cut-off frequency of an arbitrary mode (f/fc), the ratio of the curvature radius to the inner diameter of the pipe (r/D) and the bend angle (α). Subsequent experimental evaluations were performed using four groups of pipes with different inner diameters and five different bends. The effect of a bend was quantitatively evaluated by comparing the reflection signals from pipe wall thinning in a straight pipe with those in a bent pipe. The results showed that the presence of a bend led to a decrease in the reflection signal behind the bend, and the extent of decrease also depended on r/D and α of the bend. Furthermore, the length or the depth of the pipe wall thinning did not noticeably affect the decrease in reflection signal, when the bend’s dimensions were certain.