{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,3]],"date-time":"2026-05-03T03:20:16Z","timestamp":1777778416485,"version":"3.51.4"},"reference-count":73,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2020,10,23]],"date-time":"2020-10-23T00:00:00Z","timestamp":1603411200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"publisher","award":["2019R1F1A1061328"],"award-info":[{"award-number":["2019R1F1A1061328"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This study performed an experimental investigation on pulsed thermography to detect internal defects, the major degradation phenomena in several structures of the secondary systems in nuclear power plants as well as industrial pipelines. The material losses due to wall thinning were simulated by drilling flat-bottomed holes (FBH) on the steel plate. FBH of different sizes in varying depths were considered to evaluate the detection capability of the proposed technique. A short and high energy light pulse was deposited on a sample surface, and an infrared camera was used to analyze the effect of the applied heat flux. The three most established signal processing techniques of thermography, namely thermal signal reconstruction (TSR), pulsed phase thermography (PPT), and principal component thermography (PCT), have been applied to raw thermal images. Then, the performance of each technique was evaluated concerning enhanced defect detectability and signal to noise ratio (SNR). The results revealed that TSR enhanced the defect detectability, detecting the maximum number of defects, PPT provided the highest SNR, especially for the deeper defects, and PCT provided the highest SNR for the shallower defects.<\/jats:p>","DOI":"10.3390\/s20216015","type":"journal-article","created":{"date-parts":[[2020,10,23]],"date-time":"2020-10-23T08:59:28Z","timestamp":1603443568000},"page":"6015","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":50,"title":["Thermographic Inspection of Internal Defects in Steel Structures: Analysis of Signal Processing Techniques in Pulsed Thermography"],"prefix":"10.3390","volume":"20","author":[{"given":"Yoonjae","family":"Chung","sequence":"first","affiliation":[{"name":"Department of Mechanical Engineering, Kongju National University, 1223-24 Cheonan-daero, Seobuk-gu, Cheonan-si 31080, Korea"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1562-9624","authenticated-orcid":false,"given":"Ranjit","family":"Shrestha","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, School of Engineering, Kathmandu University, Dhulikhel, P.O. Box, Kathmandu 6250, Nepal"}]},{"given":"Seungju","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Convergence Mechanical Engineering, Kongju National University, 1223-24 Cheonan-daero, Seobuk-gu, Cheonan-si 31080, Korea"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9547-3868","authenticated-orcid":false,"given":"Wontae","family":"Kim","sequence":"additional","affiliation":[{"name":"Division of Mechanical &amp; Automotive Engineering, Kongju National University, 1223-24 Cheonan-daero, Seobuk-gu, Cheonan-si 31080, Korea"}]}],"member":"1968","published-online":{"date-parts":[[2020,10,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"McGuire, M.F. (2008). Stainless Steels for Design Engineers, ASM International.","DOI":"10.31399\/asm.tb.ssde.9781627082860"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1199","DOI":"10.1016\/j.jcsr.2008.07.011","article-title":"Stainless Steel in Construction: A Review of Research, Applications, Challenges and Opportunities","volume":"64","author":"Baddoo","year":"2008","journal-title":"J. Constr. Steel Res."},{"key":"ref_3","unstructured":"Lister, D.H., and Cook, W.G. (2020, June 02). Nuclear Plant Materials and Corrosion. Available online: https:\/\/www.unene.ca\/essentialcandu\/pdf\/14%20-%20Nuclear%20Plant%20Materials%20and%20Corrosion.pdf."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"65","DOI":"10.1080\/18811248.2011.9711680","article-title":"Evaluation Methods for Corrosion Damage of Components in Cooling Systems of Nuclear Power Plants by Coupling Analysis of Corrosion and Flow Dynamics (V) Flow-Accelerated Corrosion Under Single-and Two-Phase Flow Conditions","volume":"48","author":"Okada","year":"2011","journal-title":"J. Nucl. Sci. Technol."},{"key":"ref_5","unstructured":"(2012). Flow accelerated corrosion in nuclear power plants. Nuclear Power-Practical Aspects, IntechOpen."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"195","DOI":"10.1016\/j.nucengdes.2013.02.018","article-title":"Evaluation Method for Pipe Wall Thinning due to Liquid Droplet Impingement","volume":"264","author":"Naitoh","year":"2013","journal-title":"Nucl. Eng. Des."},{"key":"ref_7","unstructured":"Onel, Y., Ewert, U., and Willems, P. (2000, January 15\u201321). Radiographic Wall Thickness Measurement of Pipes by a New Tomographic Algorithm. Proceedings of the 15th WCNDT, Roma, Italy."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"736","DOI":"10.1016\/j.ijpvp.2006.07.010","article-title":"The use of Radiography for Thickness Measurement and Corrosion Monitoring in Pipes","volume":"83","author":"Edalati","year":"2006","journal-title":"Int. J. Press. Vessel. Pip."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1216","DOI":"10.1016\/j.proeng.2014.03.112","article-title":"Evaluation of Pipe Wall Thickness Based on Contrast Measurement using Computed Radiography (CR)","volume":"69","author":"Rakvin","year":"2014","journal-title":"Procedia Eng."},{"key":"ref_10","unstructured":"(2008). Remote measurement of pipe wall thinning by microwaves. Advanced Nondestructive Evaluation II: Volume 2, World Scientific."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"106","DOI":"10.1016\/j.ndteint.2010.10.001","article-title":"A High-Efficiency Nondestructive Method for Remote Detection and Quantitative Evaluation of Pipe Wall Thinning using Microwaves","volume":"44","author":"Liu","year":"2011","journal-title":"NDT E Int."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"52","DOI":"10.1016\/j.ndteint.2013.03.007","article-title":"Optimizing the Frequency Range of Microwaves for High-Resolution Evaluation of Wall Thinning Locations in a Long-Distance Metal Pipe","volume":"57","author":"Liu","year":"2013","journal-title":"NDT E Int."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1077","DOI":"10.1063\/1.1781353","article-title":"Estimating the Diameter Thickness of a Pipe using the Primary Wave Velocity of a Hollow Cylindrical Guided Wave","volume":"85","author":"Nishino","year":"2004","journal-title":"Appl. Phys. Lett."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"574","DOI":"10.1016\/j.ultras.2004.12.006","article-title":"Lamb Wave Tomography of Pipe-Like Structures","volume":"43","author":"Leonard","year":"2005","journal-title":"Ultrasonics"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1463","DOI":"10.1016\/j.net.2017.05.002","article-title":"High-Temperature Ultrasonic Thickness Monitoring for Pipe Thinning in a Flow-Accelerated Corrosion Proof Test Facility","volume":"49","author":"Cheong","year":"2017","journal-title":"Nucl. Eng. Technol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"011501","DOI":"10.1115\/1.4038517","article-title":"Experimental Evaluation of Novel Hybrid Microwave\/Ultrasonic Technique to Locate and Characterize Pipe Wall Thinning","volume":"140","author":"Alobaidi","year":"2018","journal-title":"J. Press. Vessel Technol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1016\/j.ndteint.2005.06.005","article-title":"Tubing Thread Inspection by Magnetic Flux Leakage","volume":"39","author":"Jinfeng","year":"2006","journal-title":"NDT E Int."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1134\/S1061830907020088","article-title":"Detection of Gas Pipe Wall Thickness Based on Electromagnetic Flux Leakage","volume":"43","author":"Zhang","year":"2007","journal-title":"Russ. J. Nondestruct. Test."},{"key":"ref_19","unstructured":"Dutta, S.M., and Ghorbel, F.H. (2012). Measurement of Pipe Wall Thickness Using Magnetic Flux Leakage Signals. (8,134,360), U.S. Patent."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Nam, K.W., and Ahn, S.H. (2004). Fracture Behaviors and Acoustic Emission Characteristics of Pipes with Local Wall Thinning. Key Engineering Materials, Trans Tech Publications.","DOI":"10.4028\/www.scientific.net\/KEM.270-273.461"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1195","DOI":"10.3233\/JAE-2010-1238","article-title":"Quantitative Evaluation of Wall Thinning in Pipe Wall using Electromagnetic Acoustic Transducer","volume":"33","author":"Kosaka","year":"2010","journal-title":"Int. J. Appl. Electromagn. Mech."},{"key":"ref_22","unstructured":"Kojima, F., Nguyen, T., and Yamaguchi, H. (2020, June 02). Shape Identification of Pipe-wall Thinning Using Electromagnetic Acoustic Transducer. Available online: https:\/\/aip.scitation.org\/doi\/abs\/10.1063\/1.3591913."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1016\/j.ndteint.2006.07.002","article-title":"Application of Eddy Currents Induced by Permanent Magnets for Pipeline Inspection","volume":"40","author":"Nestleroth","year":"2007","journal-title":"NDT E Int."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1007\/s10921-012-0137-9","article-title":"Pulsed Eddy Current Testing of Carbon Steel Pipes\u2019 Wall-Thinning through Insulation and Cladding","volume":"31","author":"Cheng","year":"2012","journal-title":"J. Nondestruct. Eval."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1016\/j.ndteint.2015.06.002","article-title":"Quantitative Non-Destructive Evaluation of Wall Thinning Defect in Double-Layer Pipe of Nuclear Power Plants using Pulsed ECT Method","volume":"75","author":"Xie","year":"2015","journal-title":"NDT E Int."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1016\/S1350-4495(02)00140-8","article-title":"Infrared Detectors: An Overview","volume":"43","author":"Rogalski","year":"2002","journal-title":"Infrared Phys. Technol."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Williams, T. (2009). Thermal Imaging Cameras: Characteristics and Performance, CRC Press.","DOI":"10.1201\/9781420071863"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Czichos, H. (2013). Handbook of Technical Diagnostics: Fundamentals and Application to Structures and Systems, Springer Science & Business Media.","DOI":"10.1007\/978-3-642-25850-3"},{"key":"ref_29","first-page":"1060","article-title":"Introduction to NDT by Active Infrared Thermography","volume":"60","author":"Maldague","year":"2002","journal-title":"Mater. Eval."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1111","DOI":"10.1007\/s12206-016-0215-5","article-title":"Quantification of Defects Depth in Glass Fiber Reinforced Plastic Plate by Infrared Lock-in Thermography","volume":"30","author":"Ranjit","year":"2016","journal-title":"J. Mech. Sci. Technol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"24","DOI":"10.1016\/j.infrared.2018.05.001","article-title":"Evaluation of Coating Thickness by Thermal Wave Imaging: A Comparative Study of Pulsed and Lock-in Infrared thermography\u2013Part II: Experimental Investigation","volume":"92","author":"Ranjit","year":"2018","journal-title":"Infrared Phys. Technol."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"12305","DOI":"10.3390\/s140712305","article-title":"Infrared Thermography for Temperature Measurement and Non-Destructive Testing","volume":"14","author":"Usamentiaga","year":"2014","journal-title":"Sensors"},{"key":"ref_33","unstructured":"Maldague, X.P. (2001). Nondestructive Testing Handbook. 3. Infrared and Thermal Testing, American Society for Nondestructive Testing."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1016\/j.infrared.2013.03.006","article-title":"Infrared Thermography for Condition monitoring\u2013A Review","volume":"60","author":"Bagavathiappan","year":"2013","journal-title":"Infrared Phys. Technol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"2255","DOI":"10.1007\/s12541-015-0290-z","article-title":"Investigation of Lock-in Infrared Thermography for Evaluation of Subsurface Defects Size and Depth","volume":"16","author":"Ranjit","year":"2015","journal-title":"Int. J. Precis. Eng. Manuf."},{"key":"ref_36","unstructured":"Maldague, X. (2001). Theory and Practice of Infrared Technology for Nondestructive Testing, John Wiley & Sons."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"52","DOI":"10.1016\/j.ndteint.2014.04.002","article-title":"Modelling and Evaluation of Pulsed and Pulse Phase Thermography through Application of Composite and Metallic Case Studies","volume":"66","author":"Waugh","year":"2014","journal-title":"NDT E Int."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"3962","DOI":"10.1063\/1.351366","article-title":"Thermal Wave Imaging with Phase Sensitive Modulated Thermography","volume":"71","author":"Busse","year":"1992","journal-title":"J. Appl. Phys."},{"key":"ref_39","unstructured":"Gleiter, A., Spiessberger, C., and Busse, G. (2020, June 02). Phase Angle Thermography for Depth Resolved Defect Characterization. Available online: https:\/\/aip.scitation.org\/doi\/abs\/10.1063\/1.3114300."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"693","DOI":"10.1016\/S0035-3159(98)80047-0","article-title":"Lock-in Thermography for Nondestructive Evaluation of Materials","volume":"37","author":"Wu","year":"1998","journal-title":"Rev. G\u00e9n\u00e9rale Therm."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"191","DOI":"10.1016\/j.infrared.2012.01.001","article-title":"Quantification of Defects in Composites and Rubber Materials using Active Thermography","volume":"55","author":"Lahiri","year":"2012","journal-title":"Infrared Phys. Technol."},{"key":"ref_42","first-page":"239","article-title":"Theoretical and Practical Aspects of the Thermal Nondestructive Testing of Bonded Structures","volume":"5","author":"Vavilov","year":"1982","journal-title":"Acad. Press Res. Tech. Nondestruct. Test."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"104907","DOI":"10.1063\/1.2732443","article-title":"The Effect of Size on the Quantitative Estimation of Defect Depth in Steel Structures using Lock-in Thermography","volume":"101","author":"Wallbrink","year":"2007","journal-title":"J. Appl. Phys."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"119","DOI":"10.1016\/j.ndteint.2007.08.006","article-title":"Quantitative Determination of a Subsurface Defect of Reference Specimen by Lock-in Infrared Thermography","volume":"41","author":"Choi","year":"2008","journal-title":"NDT E Int."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"104","DOI":"10.1016\/j.ndteint.2011.09.002","article-title":"Research on the Quantitative Analysis of Subsurface Defects for Non-Destructive Testing by Lock-in Thermography","volume":"45","author":"Junyan","year":"2012","journal-title":"NDT E Int."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1080\/17686733.2015.1013663","article-title":"Defect Depth Quantification using Lock-in Thermography","volume":"12","author":"Delanthabettu","year":"2015","journal-title":"Quant. InfraRed Thermogr. J."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"676","DOI":"10.1016\/j.infrared.2016.04.033","article-title":"Application of Thermal Wave Imaging and Phase Shifting Method for Defect Detection in Stainless Steel","volume":"76","author":"Shrestha","year":"2016","journal-title":"Infrared Phys. Technol."},{"key":"ref_48","doi-asserted-by":"crossref","unstructured":"Maldague, X.P., Shiryaev, V.V., Boisvert, E., and Vavilov, V.P. (1995, January 19\u201321). Transient Thermal Nondestructive Testing (NDT) of Defects in Aluminum Panels. Proceedings of the Thermosense XVII: An International Conference on Thermal Sensing and Imaging Diagnostic Applications, Orlando, FL, USA.","DOI":"10.1117\/12.204860"},{"key":"ref_49","unstructured":"Deemer, C. (2020, June 02). Front-Flash Thermal Imaging Characterization of Continuous Fiber Ceramic Composites, Available online: https:\/\/www.osti.gov\/biblio\/10924."},{"key":"ref_50","unstructured":"(2007). Active infrared thermography techniques for the nondestructive testing of materials. Ultrasonic and Advanced Methods for Nondestructive Testing and Material Characterization, World Scientific."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"363","DOI":"10.1016\/j.infrared.2012.02.004","article-title":"Reconstruction of Size and Depth of Simulated Defects in Austenitic Steel Plate using Pulsed Infrared Thermography","volume":"55","author":"Oliferuk","year":"2012","journal-title":"Infrared Phys. Technol."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"2694","DOI":"10.1063\/1.362662","article-title":"Pulse Phase Infrared Thermography","volume":"79","author":"Maldague","year":"1996","journal-title":"J. Appl. Phys."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1016\/S1350-4495(02)00138-X","article-title":"Advances in Pulsed Phase Thermography","volume":"43","author":"Maldague","year":"2002","journal-title":"Infrared Phys. Technol."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"1337","DOI":"10.1117\/1.1566969","article-title":"Reconstruction and Enhancement of Active Thermographic Image Sequences","volume":"42","author":"Shepard","year":"2003","journal-title":"Opt. Eng."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"521","DOI":"10.1016\/S0263-8223(02)00161-7","article-title":"Principal Component Thermography for Flaw Contrast Enhancement and Flaw Depth Characterisation in Composite Structures","volume":"58","author":"Rajic","year":"2002","journal-title":"Compos. Struct."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"333","DOI":"10.1080\/10589751003660434","article-title":"Wall Thinning Defect Estimation using Pulsed IR Thermography in Transmission Mode","volume":"25","author":"Vageswar","year":"2010","journal-title":"Nondestr. Test. Eval."},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1016\/j.ndteint.2012.02.008","article-title":"Depth Prediction of Non-Air Interface Defect using Pulsed Thermography","volume":"48","author":"Zeng","year":"2012","journal-title":"NDT E Int."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"501","DOI":"10.1016\/j.ndteint.2008.05.007","article-title":"Matched Excitation Energy Comparison of the Pulse and Lock-in Thermography NDE Techniques","volume":"41","author":"Pickering","year":"2008","journal-title":"NDT E Int."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"275","DOI":"10.1016\/j.infrared.2013.05.009","article-title":"Quantitative Evaluation of Optical Lock-in and Pulsed Thermography for Aluminum Foam Material","volume":"60","author":"Duan","year":"2013","journal-title":"Infrared Phys. Technol."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"655","DOI":"10.1016\/j.ndteint.2011.06.008","article-title":"A Comparison of the Pulsed, Lock-in and Frequency Modulated Thermography Nondestructive Evaluation Techniques","volume":"44","author":"Chatterjee","year":"2011","journal-title":"NDT E Int."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"559","DOI":"10.1016\/S0963-8695(02)00029-4","article-title":"Comparison between Thermographic Techniques for Frescoes NDT","volume":"35","author":"Carlomagno","year":"2002","journal-title":"NDT E Int."},{"key":"ref_62","first-page":"45","article-title":"Modelling of Pulse Thermography for Defect Detection in Aluminium Structures: Assessment on Reflection and Transmission Measurement","volume":"13","author":"Shrestha","year":"2017","journal-title":"World J. Model. Simul."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"124","DOI":"10.1016\/j.infrared.2017.04.016","article-title":"Evaluation of Coating Thickness by Thermal Wave Imaging: A Comparative Study of Pulsed and Lock-in Infrared thermography\u2013Part I: Simulation","volume":"83","author":"Shrestha","year":"2017","journal-title":"Infrared Phys. Technol."},{"key":"ref_64","unstructured":"Carslaw, H.S., and Jaeger, J.C. (1959). Conduction of Heat in Solid, Clarendon Press. [2nd ed.]."},{"key":"ref_65","first-page":"101","article-title":"On Signal Transforms Applied to Pulsed Thermography","volume":"9","author":"Galmiche","year":"2006","journal-title":"Recent Res. Dev. Appl. Phys."},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"167","DOI":"10.3166\/qirt.7.167-187","article-title":"Improvement of the Detection of Defects by Pulse Thermography Thanks to the TSR Approach in the Case of a Smart Composite Repair Patch","volume":"7","author":"Balageas","year":"2010","journal-title":"Quant. InfraRed Thermogr. J."},{"key":"ref_67","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1016\/j.ndteint.2017.05.003","article-title":"Characterization of Defects of Pulsed Thermography Inspections by Orthogonal Polynomial Decomposition","volume":"91","year":"2017","journal-title":"NDT E Int."},{"key":"ref_68","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.bbe.2014.07.002","article-title":"The Thermographic Signal Reconstruction Method: A Powerful Tool for the Enhancement of Transient Thermographic Images","volume":"35","author":"Balageas","year":"2015","journal-title":"Biocybern. Biomed. Eng."},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"93","DOI":"10.1016\/j.ndteint.2018.07.004","article-title":"Image Processing Based Quantitative Damage Evaluation in Composites with Long Pulse Thermography","volume":"99","author":"Wang","year":"2018","journal-title":"NDT E Int."},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"47","DOI":"10.3166\/qirt.1.47-70","article-title":"Pulsed Phase Thermography Reviewed","volume":"1","author":"Maldague","year":"2004","journal-title":"Quant. Infrared Thermogr. J."},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"58","DOI":"10.1016\/j.infrared.2016.09.012","article-title":"Comparison of Three Thermographic Post Processing Methods for the Assessment of a Repaired Aluminum Plate with Composite Patch","volume":"79","author":"Daryabor","year":"2016","journal-title":"Infrared Phys. Technol."},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"78","DOI":"10.1016\/j.infrared.2018.08.027","article-title":"Non-Destructive Testing and Evaluation of Materials using Active Thermography and Enhancement of Signal to Noise Ratio through Data Fusion","volume":"94","author":"Shrestha","year":"2018","journal-title":"Infrared Phys. Technol."},{"key":"ref_73","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1016\/j.infrared.2018.11.008","article-title":"Wavelet Transform Applied to Lock-in Thermographic Data for Detection of Inclusions in Composite Structures: Simulation and Experimental Studies","volume":"96","author":"Shrestha","year":"2019","journal-title":"Infrared Phys. Technol."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/21\/6015\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T10:26:45Z","timestamp":1760178405000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/21\/6015"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,10,23]]},"references-count":73,"journal-issue":{"issue":"21","published-online":{"date-parts":[[2020,11]]}},"alternative-id":["s20216015"],"URL":"https:\/\/doi.org\/10.3390\/s20216015","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,10,23]]}}}