Pedram Seyed Kamran, Fateri Sina, Gan Lu, Haig Alex, Thornicroft Keith
Center of Electronic System Research (CESR), Brunel University, Kingston Lane, Uxbridge, Middlesex UB8 3PH, UK; TWI Ltd, Granta Park, Great Abington, Cambridge CB21 6AL, UK.
TWI Ltd, Granta Park, Great Abington, Cambridge CB21 6AL, UK.
Ultrasonics. 2018 Feb;83:48-59. doi: 10.1016/j.ultras.2017.08.002. Epub 2017 Aug 24.
Ultrasonic guided wave (UGW) systems are broadly used in several branches of industry where the structural integrity is of concern. In those systems, signal interpretation can often be challenging due to the multi-modal and dispersive propagation of UGWs. This results in degradation of the signals in terms of signal-to-noise ratio (SNR) and spatial resolution. This paper employs the split-spectrum processing (SSP) technique in order to enhance the SNR and spatial resolution of UGW signals using the optimized filter bank parameters in real time scenario for pipe inspection. SSP technique has already been developed for other applications such as conventional ultrasonic testing for SNR enhancement. In this work, an investigation is provided to clarify the sensitivity of SSP performance to the filter bank parameter values for UGWs such as processing bandwidth, filter bandwidth, filter separation and a number of filters. As a result, the optimum values are estimated to significantly improve the SNR and spatial resolution of UGWs. The proposed method is synthetically and experimentally compared with conventional approaches employing different SSP recombination algorithms. The Polarity Thresholding (PT) and PT with Minimization (PTM) algorithms were found to be the best recombination algorithms. They substantially improved the SNR up to 36.9dB and 38.9dB respectively. The outcome of the work presented in this paper paves the way to enhance the reliability of UGW inspections.
超声导波（UGW）系统广泛应用于多个关注结构完整性的工业领域。在这些系统中，由于UGW的多模态和色散传播，信号解释往往具有挑战性。这导致信号在信噪比（SNR）和空间分辨率方面下降。本文采用分裂谱处理（SSP）技术，以便在管道检测的实时场景中使用优化的滤波器组参数来提高UGW信号的SNR和空间分辨率。SSP技术已经为其他应用开发，如用于提高SNR的传统超声检测。在这项工作中，进行了一项研究，以阐明SSP性能对UGW的滤波器组参数值的敏感性，如处理带宽、滤波器带宽、滤波器间距和滤波器数量。结果，估计出最佳值以显著提高UGW的SNR和空间分辨率。将所提出的方法与采用不同SSP重组算法的传统方法进行了综合和实验比较。发现极性阈值（PT）和带最小化的PT（PTM）算法是最佳的重组算法。它们分别将SNR大幅提高到36.9dB和38.9dB。本文所呈现的工作成果为提高UGW检测的可靠性铺平了道路。
