1,721,101 research outputs found
NMR relaxometry and IR thermography to study ancient cotton paper bookbinding
No full textDefects related to degradation were observed in an ancient book paperboard cover through nuclear magnetic resonance relaxometry and infrared thermography. Data collected with this combined method allowed identifying areas with moisture content and thermal diffusivity anomalies within the front board, corresponding to the different conservation status of the cellulose-based material. Non-destructive testing analytical procedures provide comprehensive knowledge for preserving precious library archives
A Physics-Informed Neural Network Method for Defect Identification in Polymer Composites Based on Pulsed Thermography †
Full text linkDefect detection in composite materials using active thermography is a well-studied field, and many thermographic data analysis methods have been proposed to facilitate defect visibility enhancement. In this work, we introduce a deep learning method that is constrained by known heat transfer phenomena described by a series of governing equations, also known in the literature as the physics-informed neural network (PINN). The accurate reconstruction of background information based on thermal images facilitates the identification of subsurface defects and reduction in noises caused by an uneven background and heating. The authors illustrate the method’s feasibility through experimental results obtained after pulsed thermography (PT) on a carbon fiber-reinforced polymer (CFRP) specimen
La termografia applicata alla salvaguardia di strutture architettoniche a carattere religioso della provincia dell'Aquila
No full textS. Maria ad Cryptas (L’Aquila): un esempio di diagnostica termografica preventiva per il consolidamento
No full textA numerical-thermal-thermographic NDT evaluation of an ancient marquetry integrated with X-ray and XRF surveys
No full textConservation of artworks is of paramount importance nowadays around the world. Clever conservation by using non-destructive testing techniques is highly appreciated by restorers and art historians. Among these, active infrared thermography needs the use of numerical simulations concerning the heat transfer from the heat source into the target. This, in order to gently heat the precious surface by avoiding any type of damage, such as colour changes and/or shrinkage and warpage effects, therefore, the understanding of the nature of the pigments, as well as the mapping of the support and eventual foreign materials is of primary importance in the survey. It is possible to accomplish these tasks by applying, e.g. X-Ray Fluorescence spectroscopy and radiography (X-Ray), respectively. Here, the latter techniques have been used on an ancient marquetry sample. Consequently, a thermographic inspection was performed, while a thermal-numerical simulation was implemented in ANSYS (R) environment. Numerical simulations were able to visualize some types of defects by calibrating the thermal inspection based on a comparison among defective and sound areas. Results demonstrated how such an integrated method is useful to provide robust information without damage to the work of art under restoration
The use of halogen lamps and pulse-compression thermography for the non-destructive evaluation of a ceramic tile
No full textThis paper shows the application of the pulse-compression thermography for inspecting a ceramic tile containing different defects buried at different depths. The selection of an optimal coded waveform for modulating the on/off state of a halogen lamp systems plays a key role for the fruitful exploitation of such technique. This is thus discussed in detail considering the thermal properties of the inspected sample, which are very similar to that of other masonry materials used in civil engineering applications. The results shows that the proposed methodology is capable of evaluating the inner structure of the tile and to discriminate each defects in terms of its depth from the inspected surface
Thermal contrast computation: il rilievo di difetti simulati subsuperficiali per mezzo della termografia
No full textThree-Dimensional Non-Destructive Inspection Using Novel Infrared-Terahertz Fusion Approaches †
Full text linkThe imaging of structures with a complex material composition and geometry is still a challenge in the field of non-destructive testing (NDT). In this study, a non-invasive imaging technique is proposed for the non-destructive inspection of both cultural heritage and natural fiber composites. The proposed technique combines the surface information provided by infrared thermography (IRT) and the internal structure retrieved with terahertz (THz) time-domain spectroscopy using an unsupervised deep residual fusion network. Experiments show that the fusion results contain more material information than a single modality. In addition, 3D imaging has been achieved using the fusion results on natural fiber composites
Learning Thermographic Models for Optimal Image Processing of Decorated Surfaces
Full text linkThe use of infrared thermography presents unique perspectives in imaging of artifacts to help interrogate their surface and subsurface characteristics, highlight deviations and detect contrast. This research capitalizes on active and passive thermal imagery along with advanced machine learning-based algorithms for pre- and post-processing of acquired scans. Such codes operate efficiently (compress data) to help link the observed temperature variations and the thermophysical parameters of targeted samples. One such processing modality is dictionary learning, which infers a “frame dictionary” to help represent the scans as linear combinations of a small set of features, thus training data to show a sparse representation. This technique (along factorization and component analysis-based methods) was used in current research on ancient polychrome marquetries aimed at detecting aging anomalies. The presented research is unique in terms of the targeted samples and the applied approaches and should provide specific guidance to similar domains
NDT Methods in Artwork Corrosion Monitoring
No full textThe interaction of materials with the atmosphere has recently received increased attention. Although the interaction
between atmosphere chemistry, weathering and pollutants deposition is complex, there is a need for measuring the
surface materials lost through weathering and acid rain by art objects. In fact, data regarding material response to
different conditions can be used to predict long-term trends in degradation as well as to assess deterioration process
parameters. Conventional inspection techniques, such as ultrasonic measurements or X-ray radiography, can be timeconsuming
and/or expensive. In principle, methods to monitor artwork corrosion should have the following features:
non-contact nature, fast and inexpensive operations, good sensitivity. In this paper an investigation on detection and
monitoring of artwork corrosion by infrared thermography and optical techniques is carried out. In IR thermography,
material loss is related to thermal contrast, which is defined as a suitable normalization of temperature differences on the
specimen. Optical techniques basically rely on optical contouring, which leads to a 3D map of the surface. Experimental
results obtained using simple inversion procedure for IR data are compared with optical results
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