あと少しで今年度も半分終わりかと少し憂鬱になっていた９月下旬、嬉しい知らせが参りました。Xu先生が筆頭著者＆責任著者としてNDT&E International誌に投稿していた論文の受理通知です。Xu先生はこちらに１年間滞在し、学生指導も含めて非常に大きな貢献をしてくれました。現在はAnhui University of Technologyに戻ってしまっておりますが、このような形でXu先生との1年が形になったことは非常に嬉しく思うところです。今後も色々と一緒にできることを願っております。
論文の概要は以下。
Title: Probabilistic detection assessment based on one-dimensional signal distribution in eddy current testing under low signal-to-noise ratio (信号の1次元分布に基づく低信号対雑音比条件での渦電流探傷信号の確率論的なきず検出性評価)
Abstract: This study proposes a novel approach for evaluating the probability of detection (POD) by considering the spatial distribution characteristics of measured signals, with a particular focus on its application in eddy current testing (ECT) under a low signal-to-noise ratio (SNR) situation. To simulate such a situation, eighteen welded austenitic stainless-steel plates were prepared, and seventy-three artificial slits were introduced parallel to their weld beads to simulate weld cracks. ECT signals were collected from the samples using a uniform eddy current probe. Experimental results revealed that evaluating flaw presence solely based on the maximum amplitude of measured signals, as employed in the conventional â-a approach, was quite misleading. In contrast, the proposed approach, which quantifies deviations in the one-dimensional spatial distributions of signals inspired by the Gini coefficient used in economics to assess income inequality, provided fewer false positives and false negatives. A multi-parameter POD model was then developed, formulating POD as a function of both the length and depth of a slit using these deviations, namely the Gini values. Decision thresholds, which are critical for POD estimation, were determined from the maximum signal features of the seven slit-free samples. The results demonstrate that the proposed Gini-based approach enables a simpler POD analysis while reducing false detections and mitigating the challenge of setting a proper decision threshold under a low SNR situation, in contrast to the conventional amplitude-based method.