{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,17]],"date-time":"2026-03-17T01:14:38Z","timestamp":1773710078988,"version":"3.50.1"},"reference-count":39,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2021,12,30]],"date-time":"2021-12-30T00:00:00Z","timestamp":1640822400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["52008205"],"award-info":[{"award-number":["52008205"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Natural Science Foundation for College and University in Jiangsu Province","award":["20KJB560013"],"award-info":[{"award-number":["20KJB560013"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Ultrasonic sensors have been extensively used in the nondestructive testing of materials for flaw detection. For polycrystalline materials, however, due to the scattering nature of the material, which results in strong grain noise and attenuation of the ultrasonic signal, accurate detection of flaws is particularly difficult. In this paper, a novel flaw-detection method using a simple ultrasonic sensor is proposed by exploiting time-frequency features of an ultrasonic signal. Since grain scattering mostly happens in the Rayleigh scattering region, it is possible to separate grain-scattered noise from flaw echoes in the frequency domain employing their spectral difference. We start with the spectral modeling of grain noise and flaw echo, and how the two spectra evolve with time is established. Then, a time-adaptive spectrum model for flaw echo is proposed, which serves as a template for the flaw-detection procedure. Next, a specially designed similarity measure is proposed, based on which the similarity between the template spectrum and the spectrum of the signal at each time point is evaluated sequentially, producing a series of matching coefficients termed moving window spectrum similarity (MWSS). The time-delay information of flaws is directly indicated by the peaks of MWSSs. Finally, the performance of the proposed method is validated by both simulated and experimental signals, showing satisfactory accuracy and efficiency.<\/jats:p>","DOI":"10.3390\/s22010268","type":"journal-article","created":{"date-parts":[[2021,12,30]],"date-time":"2021-12-30T23:29:07Z","timestamp":1640906947000},"page":"268","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Flaw Detection in Highly Scattering Materials Using a Simple Ultrasonic Sensor Employing Adaptive Template Matching"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7725-9980","authenticated-orcid":false,"given":"Biao","family":"Wu","sequence":"first","affiliation":[{"name":"College of Civil Engineering, Nanjing Tech University, Nanjing 211816, China"}]},{"given":"Yong","family":"Huang","sequence":"additional","affiliation":[{"name":"Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education, School of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China"},{"name":"Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology, Harbin Institute of Technology, Harbin 150090, China"}]}],"member":"1968","published-online":{"date-parts":[[2021,12,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"608","DOI":"10.1063\/1.1724072","article-title":"Ultrasonic Propagation in Liquids: I. Application of Pulse Technique to Velocity and Absorption Meas-urements at 15 Megacycle","volume":"14","author":"Pellam","year":"1946","journal-title":"J. Chem. Phys."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"207","DOI":"10.1016\/j.sna.2014.05.026","article-title":"Fabrication and characterization of annular-array, high-frequency, ultrasonic transducers based on PZT thick film","volume":"216","author":"Filoux","year":"2014","journal-title":"Sens. Actuators A"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Sha, G., and Lissenden, C.J. (2021). Modeling Magnetostrictive Transducers for Structural Health Monitoring: Ultrasonic Guided Wave Generation and Reception. Sensors, 21.","DOI":"10.3390\/s21237971"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Brenner, K., Ergun, A.S., and Firouzi, K. (2019). Advances in Capacitive Micromachined Ultrasonic Transducers. Micromachines, 10.","DOI":"10.3390\/mi10020152"},{"key":"ref_5","first-page":"800152","article-title":"Advances ign Capacitive Microfmachined Ultrasonic Transynthducetrs","volume":"10","author":"Brenner","year":"2021","journal-title":"Mic Aperture Iomagching Syst."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"494","DOI":"10.1177\/1475921713507100","article-title":"Laser ultrasonic imaging and damage detection for a rotating structure","volume":"12","author":"Park","year":"2013","journal-title":"Struct. Health Monit."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1016\/j.ndteint.2009.10.001","article-title":"Defect detection using ultrasonic arrays: The multi-mode total focusing method","volume":"43","author":"Zhang","year":"2010","journal-title":"NDTE Int."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1634","DOI":"10.1109\/TUFFC.2019.2925974","article-title":"Sizing Subwavelength Defects with Ultrasonic Imagery: An Assessment of Su-per-Resolution Imaging on Simulated Rough Defect","volume":"66","author":"Elliott","year":"2019","journal-title":"IEEE Trans. Ultrason. Ferroelect. Freq. Contr."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s10921-020-00743-9","article-title":"Noise Reduction for Improvement of Ultrasonic Monitoring Using Coda Wave Interferometry on a Real Bridge","volume":"40","author":"Wang","year":"2021","journal-title":"J. Nondestruct. Eval."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Chakraborty, J., Katunin, A., and Klikowicz, P. (2019). Early crack detection of reinforced concrete structure using embedded sensors. Sensors, 19.","DOI":"10.3390\/s19183879"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Wang, X., Chakraborty, J., and Bassil, A. (2020). Detection of Multiple Cracks in Four-Point Bending Tests Using the Coda Wave Interferometry Method. Sensors, 20.","DOI":"10.3390\/s20071986"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"095013","DOI":"10.1088\/1361-665X\/ac1304","article-title":"A feasibility study on monitoring of weld fatigue crack growth based on coda wave interferometry (CWI)","volume":"30","author":"Zhou","year":"2021","journal-title":"Smart Mater. Struct."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1016\/0041-624X(82)90003-8","article-title":"Flaw to gain echo enhancement by split spectrum processing","volume":"20","author":"Newhouse","year":"1982","journal-title":"Ultrasonics"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1109\/58.484470","article-title":"Nonlinear clutter suppression using split spectrum processing and optimal detection, IEEE Trans","volume":"43","author":"Gustafsson","year":"1996","journal-title":"Ultrason. Ferroelect. Freq. Contr."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"56","DOI":"10.1016\/j.ultras.2007.09.003","article-title":"Normalized split-spectrum: A detection approach","volume":"48","author":"Bosch","year":"2008","journal-title":"Ultrasonics"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"76","DOI":"10.1016\/j.ndteint.2016.10.005","article-title":"A Bayesian Approach for Sparse Flaw Detection from Noisy Signals for Ultrasonic NDT","volume":"85","author":"Wu","year":"2017","journal-title":"NDT E Int."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1063","DOI":"10.1016\/j.ultras.2006.05.101","article-title":"Noise reduction in ultrasonic NDT using undecimated wavelet transforms","volume":"44","author":"Pardo","year":"2006","journal-title":"Ultrasonics"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"752","DOI":"10.1016\/j.ultras.2009.05.010","article-title":"Signal-to-noise ratio enhancement based on wavelet filtering in ultrasonic testing","volume":"49","author":"Matz","year":"2009","journal-title":"Ultra-Sonics"},{"key":"ref_19","first-page":"1519","article-title":"; Continuous Wavelet Transform Analysis for the Enhancement of Signal-to-noise Ratio in Coarse Grain Austenitic Stainless Steel","volume":"72","author":"Sharma","year":"2014","journal-title":"Mater. Eval."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Tiwari, K.A., Raisutis, R., and Samaitis, V. (2017). Hybrid Signal Processing Technique to Improve the Defect Estimation in Ultrasonic Non-Destructive Testing of Composite Structures. Sensors, 17.","DOI":"10.3390\/s17122858"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"676","DOI":"10.1016\/j.ultras.2013.09.004","article-title":"Ultrasonic flaw detection using threshold modified S-transform","volume":"54","author":"Benammar","year":"2014","journal-title":"Ultrasonics"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1134\/S1061830918020080","article-title":"Ultrasonic Flaw Echoes Detection Based on Generalized S-Transform","volume":"54","author":"Zeng","year":"2018","journal-title":"Russ. J. Nondestr. Test."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"2963","DOI":"10.1121\/1.2982414","article-title":"Signal denoising and ultrasonic flaw detection via overcomplete and sparse representations","volume":"124","author":"Zhang","year":"2008","journal-title":"J. Acoust. Soc. Am."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"347","DOI":"10.1177\/1475921716665252","article-title":"Guided-wave signal processing by the sparse Bayesian learning approach employing Gabor pulse model","volume":"16","author":"Wu","year":"2017","journal-title":"Struct. Health Monit."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1235","DOI":"10.1177\/1475921718790212","article-title":"Sparse recovery of multiple dispersive guided-wave modes for defect localization using a Bayesian approach","volume":"18","author":"Wu","year":"2019","journal-title":"Struct. Health Monit."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"711","DOI":"10.1121\/1.1909401","article-title":"Ultrasonic Attenuation Caused by Scattering in Polycrystalline Metals","volume":"37","author":"Papadakis","year":"1965","journal-title":"J. Acoust. Soe. Am."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Goebbels, K., Hirsekorn, S., and Willems, H. (1984, January 14\u201316). The use of ultrasound in the determination of microstructure A review. Proceedings of the IEEE Ultrasonics Symposium, Dallas, TX, USA.","DOI":"10.1109\/ULTSYM.1984.198421"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"3165","DOI":"10.1121\/1.417126","article-title":"Spectral analysis for ultrasonic nondestructive evaluation applications using autoregressive, Prony, and multiple signal classification methods","volume":"100","author":"Saniie","year":"1996","journal-title":"J. Acoust. Soc. Am."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"400","DOI":"10.1121\/1.396944","article-title":"Statistical evaluation of backscattered ultrasonic grain signals","volume":"84","author":"Saniie","year":"1988","journal-title":"J. Acoust. Soc. Am."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"365","DOI":"10.1109\/58.19177","article-title":"Analysis of homomorphic processing for ultrasonic grain signal characterizations","volume":"36","author":"Saniie","year":"1989","journal-title":"IEEE Trans. Ultrason. Ferroelect. Freq. Contr."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"717","DOI":"10.1016\/j.ultras.2005.05.001","article-title":"A methodology for structural health monitoring with diffuse ultrasonic waves in the presence of temper-ature variations","volume":"43","author":"Lu","year":"2005","journal-title":"Ultrasonics"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"517","DOI":"10.1016\/j.ultras.2009.11.002","article-title":"Efficient temperature compensation strategies for guided wave structural health monitoring","volume":"50","author":"Croxford","year":"2010","journal-title":"Ultrasonics"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"851","DOI":"10.1109\/TUFFC.2018.2813278","article-title":"Dynamic time warping temperature compensation for guided wave structural health monitoring","volume":"65","author":"Douglass","year":"2018","journal-title":"IEEE Trans. Ultrason. Ferroelect. Freq. Contr."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"508","DOI":"10.1177\/1475921718759272","article-title":"Compensation of phase response changes in ultrasonic transducers caused by temperature variations","volume":"18","author":"Herdovics","year":"2019","journal-title":"Struct. Health Monit."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"399","DOI":"10.1016\/S0301-5629(00)00349-5","article-title":"An adaptive template-matching method and its application to the boundary detection of brachial artery ultrasound scans","volume":"27","author":"Fan","year":"2001","journal-title":"Ultrasound. Med. Biol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"380","DOI":"10.1016\/j.infrared.2012.01.006","article-title":"; Infrared point target detection with improved template matching","volume":"55","author":"Liu","year":"2012","journal-title":"Infrared. Phys. Techn."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1351","DOI":"10.1109\/TPAMI.2005.181","article-title":"Iterative Kernel Principal Component Analysis for Image Modeling","volume":"27","author":"Kim","year":"2005","journal-title":"IEEE Trans. Pattern Anal. Mach. Intell."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"31","DOI":"10.1016\/S0041-624X(96)00084-4","article-title":"Studies of split spectrum processing, optimal detection, and maximum likelihood amplitude estimation using a simple clutter model","volume":"35","author":"Gustafsson","year":"1997","journal-title":"Ultrasonics"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"291","DOI":"10.1016\/S0041-624X(01)00061-0","article-title":"Combining phase and energy detection with mathematical morphology in dual time-frequency representation leads to improved SSP noise robustness","volume":"39","author":"Cudel","year":"2001","journal-title":"Ultrasonics"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/1\/268\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:56:13Z","timestamp":1760169373000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/1\/268"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,12,30]]},"references-count":39,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2022,1]]}},"alternative-id":["s22010268"],"URL":"https:\/\/doi.org\/10.3390\/s22010268","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,12,30]]}}}