Low Thermal Conductivity Materials and Very Low Heat Power: A Demanding Challenge in the Detection of Flaws in Multi-Layer Wooden Cultural Heritage Objects Solved by Pulse-Compression Thermography Technique
An inlay sample with artificial defects was inspected via the pulse-compression thermography (PuCT) technique. The sample belongs to the cultural heritage field, and it was realized by a professional restorer based on his long-time experience, imitating historical art crafting styles. The tesserae c...
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| Format: | Article |
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MDPI AG
2020-06-01
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| Series: | Applied Sciences |
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| Online Access: | https://www.mdpi.com/2076-3417/10/12/4233 |
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| author | Stefano Sfarra Stefano Laureti Gianfranco Gargiulo Hamed Malekmohammadi Mario Andrea Sangiovanni Mauro La Russa Pietro Burrascano Marco Ricci |
| author_facet | Stefano Sfarra Stefano Laureti Gianfranco Gargiulo Hamed Malekmohammadi Mario Andrea Sangiovanni Mauro La Russa Pietro Burrascano Marco Ricci |
| author_sort | Stefano Sfarra |
| collection | DOAJ |
| description | An inlay sample with artificial defects was inspected via the pulse-compression thermography (PuCT) technique. The sample belongs to the cultural heritage field, and it was realized by a professional restorer based on his long-time experience, imitating historical art crafting styles. The tesserae composing the inlay were not treated by any protective paints, so that external thermal stimuli may cause physical/mechanical alterations of the cell walls, with consequent colour changes, cracks, and eventually damage to its surface. To avoid any alteration of the sample, the PuCT technique was used for inspecting the inlay sample as it allows the heating power to be very low, while assuring enough thermal contrast for the defects to be detected after the exploitation of the pulse-compression algorithm. Even if a maximum Δ<i>T</i> slightly exceeding 1 °C was detected during the PuCT test of the inlay sample, it is shown that this is enough for detecting several defects. Further, image processing based on the Hilbert transform increases defect detection and characterization. In addition, a novel normalization technique, i.e., a pixel-by-pixel data normalization with respect to the absorbance estimated by considering a characteristic value of the compression peak, is introduced here for the first time. The proposed normalization enhances the defect detection capability with respect to the standard pixel-by-pixel amplitude visualization. This has been demonstrated for two experimental setups, both exploiting the same LED chips system as heating source but different thermal camera sensors, i.e., one in the mid-infrared spectrum, the other in the far infrared one. Thus, the present work is also the first small-scale test of a future portable system that will include low-power LED chip feed in DC by metal-oxide-semiconductor field-effect transistor (MOSFET) devices, and a handy far-infrared camera. |
| first_indexed | 2024-03-10T19:00:27Z |
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| id | doaj.art-981d74e8c3ae46d2b0fa5b650bd7fdc0 |
| institution | Directory Open Access Journal |
| issn | 2076-3417 |
| language | English |
| last_indexed | 2024-03-10T19:00:27Z |
| publishDate | 2020-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Applied Sciences |
| spelling | doaj.art-981d74e8c3ae46d2b0fa5b650bd7fdc02023-11-20T04:27:43ZengMDPI AGApplied Sciences2076-34172020-06-011012423310.3390/app10124233Low Thermal Conductivity Materials and Very Low Heat Power: A Demanding Challenge in the Detection of Flaws in Multi-Layer Wooden Cultural Heritage Objects Solved by Pulse-Compression Thermography TechniqueStefano Sfarra0Stefano Laureti1Gianfranco Gargiulo2Hamed Malekmohammadi3Mario Andrea Sangiovanni4Mauro La Russa5Pietro Burrascano6Marco Ricci7Department of Industrial and Information Engineering and Economics, University of L’Aquila, 67100 L’Aquila, ItalyDepartment of Informatics, Modeling, Electronics and Systems Engineering, University of Calabria, Via P. Bucci, Arcavacata, 87036 Rende, ItalyIndividual Company of Restoration (Gianfranco Gargiulo), Via Tiberio 7b, I-80073 Capri, ItalyDepartment of Engineering, Polo Scientifico Didattico di Terni, University of Perugia, 05100 Terni, ItalyDepartment of Informatics, Modeling, Electronics and Systems Engineering, University of Calabria, Via P. Bucci, Arcavacata, 87036 Rende, ItalyDepartment of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci, Arcavacata, 87036 Rende, ItalyDepartment of Engineering, Polo Scientifico Didattico di Terni, University of Perugia, 05100 Terni, ItalyDepartment of Informatics, Modeling, Electronics and Systems Engineering, University of Calabria, Via P. Bucci, Arcavacata, 87036 Rende, ItalyAn inlay sample with artificial defects was inspected via the pulse-compression thermography (PuCT) technique. The sample belongs to the cultural heritage field, and it was realized by a professional restorer based on his long-time experience, imitating historical art crafting styles. The tesserae composing the inlay were not treated by any protective paints, so that external thermal stimuli may cause physical/mechanical alterations of the cell walls, with consequent colour changes, cracks, and eventually damage to its surface. To avoid any alteration of the sample, the PuCT technique was used for inspecting the inlay sample as it allows the heating power to be very low, while assuring enough thermal contrast for the defects to be detected after the exploitation of the pulse-compression algorithm. Even if a maximum Δ<i>T</i> slightly exceeding 1 °C was detected during the PuCT test of the inlay sample, it is shown that this is enough for detecting several defects. Further, image processing based on the Hilbert transform increases defect detection and characterization. In addition, a novel normalization technique, i.e., a pixel-by-pixel data normalization with respect to the absorbance estimated by considering a characteristic value of the compression peak, is introduced here for the first time. The proposed normalization enhances the defect detection capability with respect to the standard pixel-by-pixel amplitude visualization. This has been demonstrated for two experimental setups, both exploiting the same LED chips system as heating source but different thermal camera sensors, i.e., one in the mid-infrared spectrum, the other in the far infrared one. Thus, the present work is also the first small-scale test of a future portable system that will include low-power LED chip feed in DC by metal-oxide-semiconductor field-effect transistor (MOSFET) devices, and a handy far-infrared camera.https://www.mdpi.com/2076-3417/10/12/4233pulse-compression thermographyinlayLED chipsdefectsdata processinglow power heat sources |
| spellingShingle | Stefano Sfarra Stefano Laureti Gianfranco Gargiulo Hamed Malekmohammadi Mario Andrea Sangiovanni Mauro La Russa Pietro Burrascano Marco Ricci Low Thermal Conductivity Materials and Very Low Heat Power: A Demanding Challenge in the Detection of Flaws in Multi-Layer Wooden Cultural Heritage Objects Solved by Pulse-Compression Thermography Technique Applied Sciences pulse-compression thermography inlay LED chips defects data processing low power heat sources |
| title | Low Thermal Conductivity Materials and Very Low Heat Power: A Demanding Challenge in the Detection of Flaws in Multi-Layer Wooden Cultural Heritage Objects Solved by Pulse-Compression Thermography Technique |
| title_full | Low Thermal Conductivity Materials and Very Low Heat Power: A Demanding Challenge in the Detection of Flaws in Multi-Layer Wooden Cultural Heritage Objects Solved by Pulse-Compression Thermography Technique |
| title_fullStr | Low Thermal Conductivity Materials and Very Low Heat Power: A Demanding Challenge in the Detection of Flaws in Multi-Layer Wooden Cultural Heritage Objects Solved by Pulse-Compression Thermography Technique |
| title_full_unstemmed | Low Thermal Conductivity Materials and Very Low Heat Power: A Demanding Challenge in the Detection of Flaws in Multi-Layer Wooden Cultural Heritage Objects Solved by Pulse-Compression Thermography Technique |
| title_short | Low Thermal Conductivity Materials and Very Low Heat Power: A Demanding Challenge in the Detection of Flaws in Multi-Layer Wooden Cultural Heritage Objects Solved by Pulse-Compression Thermography Technique |
| title_sort | low thermal conductivity materials and very low heat power a demanding challenge in the detection of flaws in multi layer wooden cultural heritage objects solved by pulse compression thermography technique |
| topic | pulse-compression thermography inlay LED chips defects data processing low power heat sources |
| url | https://www.mdpi.com/2076-3417/10/12/4233 |
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