I got the decision letter before leaving the lab in the evening of Oct. 25th. I was surprised the revised manuscript was accepted so quickly after resubmission although it was minor revision.
It is important to quantitatively evaluate the detectability of microwave NDT. Dr. Chen (works in China now) studied the probability of detection on full circumferential pipe wall thinning using microwaves. However, the local wall thinning with arbitrary circumferential angle is more common in reality and should be considered to prompt the practical application of proposed method.
This study investigated the influence of both the wall thinning size (including axial length, depth and circumferential angle) and its location on the detection. The probability of detection analysis was conducted to probabilistically evaluate the detectability of microwave NDT to wall thinning with arbitrary size and location. The details are as follows:
Title: Integration of Multiple Wall Thinning Parameters into the Probability of Detection Analysis for Long-Range Pipe Inspection Using Microwaves
Abstract: A three-dimensional probability of detection (POD) model integrating the depth, circumferential angle, and location of pipe wall thinning (PWT) was proposed for the probabilistic analysis of long-range pipe inspection using microwaves. Microwaves in TM01 mode were used to detect PWT with different sizes and locations (up to 13.5 m). The microwave signals reflected from the PWT were measured and processed, and their amplitudes were extracted and treated as the signal response. The results showed that the signal response was rarely influenced by the axial length of the PWT, while its natural logarithm was proportional to the natural logarithm of the PWT depth and circumferential angle. In addition, the signal response decreased exponentially with the PWT location. Subsequently, a multivariate regression model was established, and the related coefficients were estimated using the maximum likelihood method. The POD calculated from the regression model suggests that a small PWT at a far distance (e.g., 36.0 m) can be reliably detected using microwaves. Compared with a two-dimensional POD model that considers only the PWT cross-section area as the size parameter, the proposed POD model clearly shows that the POD is more dependent on the circumferential angle than on the depth of the PWT.