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Journal articles on the topic 'Thermal NDT methods'
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1
Marinetti, S., L. Finesso, and E. Marsilio. "Matrix factorization methods: Application to thermal NDT/E." NDT & E International 39, no. 8 (December 2006): 611–16. http://dx.doi.org/10.1016/j.ndteint.2006.04.008.
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Dattoma, Vito, Francesco Panella, Alessandra Pirinu, and Andrea Saponaro. "Advanced NDT Methods and Data Processing on Industrial CFRP Components." Applied Sciences 9, no. 3 (January 24, 2019): 393. http://dx.doi.org/10.3390/app9030393.
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In this work, enhanced thermal data processing is developed with experimental procedures, improving visualization algorithm for sub-surface defect detection on industrial composites. These materials are prone to successful infrared nondestructive investigation analyses, since defects are easily characterized by temperature response under thermal pulses with reliable results. Better defect characterization is achieved analyzing data with refined processing and experimental procedures, providing detailed contrasts maps where defects are better distinguished. Thermal data are analyzed for different CFRP specimens with artificial defects and experimental procedures are verified on real structural aeronautical component with internal anomalies due to impact simulation. A better computation method is found to be useful for simultaneous defect detection by means of automatic mapping of absolute contrast, optimized to identify defect boundaries.
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Nowacki, J., and N. Sieczkiewicz. "Prospective NDT methods for assessing the quality of polymer composites under production conditions." Archives of Materials Science and Engineering 2, no. 87 (October 1, 2017): 66–74. http://dx.doi.org/10.5604/01.3001.0010.7447.
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Purpose: Analysis of non-destructive testing systems polymer composite in terms of current solutions in the area of methodology and devices. Analysis of contemporary standards for non-destructive testing of polymer composites established by ASTM. Analysis of Flir ONE camera capabilities in non-destructive testing composite carbon-epoxy composites. Design/methodology/approach: The thermal imaging tests of the carbon-epoxy composite discontinuity were carried out using a thermal imaging camera and Flir One accessory for an iOS phone. The tests were performed on carbon-epoxy composite samples measuring 100x100 mm. In order to simulate the discontinuity in a sample by the Resin Transfer Molding (RTM) method, a 30x30 mm PTFE film was inserted between the reinforcement layers. The thickness of the sample with discontinuity was 2 mm. Water was added to the selected sample sites. Samples were placed on a 50°C heated plate to record thermal images and thermal images combined with visual contours of samples with simulated defects. Area Calculator – SketchAndCalc Icalc, Inc. was used to describe the size and location of the defects. Findings: As a result of the tests, the use of the Flir One thermal imaging device in epoxycarbon composite discontinuity tests has been demonstrated, and a methodology has been proposed to measure geometrical features of defects. Research limitations/implications: The description of welded joint structure and mechanical properties was based on welding toughened steels by using an innovative welding method and a filler that has been proposed. Practical implications: The development of thermal imaging studies of polymer composite discontinuity using the Flir One thermal imaging camera and accessory with iOS opens up the possibility of conducting a basic inspection of composite materials in production plants, and even for simplicity – also in small laboratories. Originality/value: In order to improve the quality of imaging of small items using the Flir One mobile camera, the use of cheap and readily available lenses used in laser optics has been tested positively.
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Plšková, Iveta, Michal Matysík, and Zdeněk Chobola. "Monitoring of Thermal Damage Evolution in Concrete Parts by Acoustic NDT Methods." Key Engineering Materials 808 (June 2019): 159–64. http://dx.doi.org/10.4028/www.scientific.net/kem.808.159.
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The paper presents the results of the experimental work which was focused on the use of the Impact-echo method for testing of concrete specimens damaged by high-temperature. The test specimens were heated to 600 and 800 °C for sixty, one hundred twenty and three hundred minutes. After heating, the samples were continuously cooled to room temperature and tested by Impact-echo method.
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Land, Patrick, Petros Stavroulakis, Richard Crossley, Patrick Bointon, Harvey Brookes, Jon Wright, Svetan Ratchev, and David Branson. "Evaluation of Thermal Roll Formed Thick Composite Panels Using Surface NDT Methods." SAE International Journal of Materials and Manufacturing 11, no. 1 (September 19, 2017): 37–42. http://dx.doi.org/10.4271/05-11-01-0005.
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Kostyleva, Liliya Yu, Oleg V. Loginovskiy, Evgeniya A. Retc, and Igor M. Yachikov. "Possibilities of using mathematical models for thermal nondestructive testing of defects in multilayer bimetallic plates." Bulletin of the South Ural State University. Ser. Computer Technologies, Automatic Control & Radioelectronics 22, no. 1 (January 2022): 53–64. http://dx.doi.org/10.14529/ctcr220104.
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There is an actual task of delamination detection in multilayer bimetallic materials. Various methods of nondestructive testing (NDT) are used to solve it, including the method of transient thermal NDT. This method consists in remote registration, visualization and analysis of thermal (temperature) fields, which depend on thermophysical and geometric characteristics, thermal effect capacity and internal structure features of the object. The internal structure defects cause the appearance of abnormal temperature zones on the object surface. Their analysis allows us to judge the presence of changes in the material as a whole or in individual areas. It is possible to understand whether there is a defect under the anomalous site, and what its parameters are, if there is an adequate mathematical model that theoretically describes the dependence of the measuring results on the properties of the object and the selected technological modes. This model is a significant component of thermal NDT systems. For the same object or process, a certain set of mathematical models can be compiled, differing in the number of factors taken into account, the assumptions made, the completeness and accuracy of the description of the state of the object or the conditions of the process. The set of factors is determined by the purpose of the study, and in order to unambiguously determine the model of the thermal state, it is necessary to describe the characteristics of the object (geometric shape and thermophysical characteristics of the material) and the heat exchange process (characteristics of heat sources, initial and boundary conditions). Aim. To analyze the existing mathematical models for the research object – a multilayer bimetallic plate with delaminations between the outer and inner layers, and to identify common approaches to modeling the processes of thermal NDT of multilayer objects. Materials and methods. The structure of the mathematical model of the thermal state of the object is determined. An analytical review of mathematical models of thermal NDT of multilayer objects is performed. Results. The requirements, assumptions and limitations for a mathematical model of thermal NDT of a multilayer bimetallic plate with delamination defects are formulated. Conclusion. On the basis of the considered approaches to the mathematical modeling of the thermal state of multilayer objects with ideal layers contact and delamination defects, the necessary factors for the development of a model for the transient thermal NDT processes of the studied objects are determined.
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Qu, Zhi, Peng Jiang, and Weixu Zhang. "Development and Application of Infrared Thermography Non-Destructive Testing Techniques." Sensors 20, no. 14 (July 10, 2020): 3851. http://dx.doi.org/10.3390/s20143851.
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Effective testing of defects in various materials is an important guarantee to ensure its safety performance. Compared with traditional non-destructive testing (NDT) methods, infrared thermography is a new NDT technique which has developed rapidly in recent years. Its core technologies include thermal excitation and infrared image processing. In this paper, several main infrared thermography nondestructive testing techniques are reviewed. Through the analysis and comparison of the detection principle, technical characteristics and data processing methods of these testing methods, the development of the infrared thermography nondestructive testing technique is presented. Moreover, the application and development trend are summarized.
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Schmid, Maximilian, Sri Krishna Bhogaraju, E. Liu, and Gordon Elger. "Comparison of Nondestructive Testing Methods for Solder, Sinter, and Adhesive Interconnects in Power and Opto-Electronics." Applied Sciences 10, no. 23 (November 28, 2020): 8516. http://dx.doi.org/10.3390/app10238516.
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Reliability is one of the major requirements for power and opto-electronic devices across all segments. High operation temperature and/or high thermomechanical stress cause defects and degradation of materials and interconnects, which may lead to malfunctions with costly or even life-threatening consequences. To avoid or at least reduce failures, nondestructive testing (NDT) methods are common within development and production of power and opto-electronics. Currently, the dominating NDT methods are X-ray, scanning acoustic microscopy (SAM), and transient thermal analysis (TTA). However, they have different strengths and weaknesses with respect to materials and mechanical designs. This paper compares these NDT methods for different interconnect technologies, i.e., reflow soldering, adhesive, and sintered interconnection. While X-ray provided adequate results for soldered interfaces, inspection of adhesives and sintered interconnects was not possible. With SAM, evaluation of adhesives and sintered interconnects was also feasible, but quality depended strongly on the sample under test. TTA enabled sufficiently detailed results for all the interconnect applications. Automated TTA equipment, as the in-house developed tester used within this investigation, enabled measurement times compatible with SAM and X-ray. In the investigations, all methods revealed their pros and cons, and their selection has to depend on the sample under tests and the required analysis depth and data details. In the paper, guidelines are formulated for an appropriate decision on the NDT method depending on sample and requirements.
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Ba, Abdoulaye, Huu Kien Bui, Gérard Berthiau, Didier Trichet, and Guillaume Wasselynck. "Simulation of induction thermography NDT technique using SIBC." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 39, no. 5 (July 3, 2020): 1071–83. http://dx.doi.org/10.1108/compel-01-2020-0007.
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Purpose This paper aims to present a lightened 3D finite element model (FEM) for coupled electromagnetic thermal simulation of the induction thermography non-destructive testing (NDT) technique to reduce the computation time. Design/methodology/approach The time harmonic electromagnetic problem is expressed in A – ϕ formulation and lightened by using the surface impedance boundary condition (SIBC) applied to both the massive induction coil surface and the surface of conductor workpiece including open cracks. The external circuit is taken into account by using the impressed voltage or the impressed current formulation. The thermal diffusion in the workpiece is solved by using surface electromagnetic power density as thermal source. Findings The accuracy and the usefulness of the method for the design of the induction thermography NDT technique have been shown with acceptable deviation compared with a full FEM model. It is also observed that at high frequency, when the ratio between the local radius of the conductor and the skin depth is high, a very good accuracy can be obtained with the SIBC methods. At lower frequency, the effect of the curvature of the surface becomes significant. In this case, the use of the Mitzner’s impedance can help to correct the error. Originality/value The SIBC can be used for both massive coil and workpieces with open cracks to alleviate 3D FEMs of the coupled electrothermal model. The implementation in matrix form of the coupled electrothermal formulation is given in details. The comparisons with reference analytical solution and full 3D FEM show the accuracy and performance of the method. In the test case presented, the computation time is 6.6 times lower than the classical model.
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Balasubramaniam, Kaleeswaran, Dominika Ziaja, Michał Jurek, Piotr Fiborek, and Paweł Malinowski. "Experimental and Numerical Analysis of Multiple Low-Velocity Impact Damages in a Glass Fibered Composite Structure." Materials 14, no. 23 (November 28, 2021): 7268. http://dx.doi.org/10.3390/ma14237268.
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Glass fiber-reinforced polymer structures (GFRPS) are widely used in civil and mechanical fields due to their light weight and corrosion resistance. However, these structures are prone to damage with very-low-energy impacts. The reliability of such structures is of prime importance before their installation and usage. This study aimed to identify, visualize, localize, and verify multiple barely visible impact damage (BVID) in a GFRPS using a combination of guided waves (GW)-based online structural health monitoring (SHM) and thermal strain-based nondestructive testing (NDT) approaches. Global NDT techniques like the use of a laser Doppler vibrometer (LDV) and digital image correlation (DIC) were used in the experimental analysis. The effectiveness of the experimental LDV-GW process was also checked numerically with the spectral element method (SEM). A threshold-based baseline free SHM approach to effectively localize the damages was proposed along with quick DIC verification of composite structure with thermal loading based on short-pulse heating as an excitation source. This study analyzed combined experimental- and numerical-based SHM-NDT methods in characterizing the multiple BVIDs located in a GFRPS.
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Krstulović-Opara, Lovre, Petra Bagavac, Antun Božanić, and Željko Domazet. "NDT of Composites Based on Active Infrared Thermography and Ultrasound Testing." Journal of Energy - Energija 70, no. 2 (June 30, 2021): 3–6. http://dx.doi.org/10.37798/202170210.
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Composite materials, such as glass and carbon reinforced ones, are characterized by inhomogeneous structure that requires non destructive testing based on uncommon evaluation methods. The presented approach is based on the active infrared thermography, supported by the A-scan ultrasound testing. The heat wave propagation induced by halogen or xenon bulbs, due to the differences in thermal conductivity, reveals material structure and anomalies. In our previous work we have developed several signal processing and depth evaluation methods, but the real engineering approach requires additional approval testing methods such as the A-scan ultrasound is. The A-scan ultrasound, based on the low frequency probe, enables approval of anomalies located by infrared thermography. The active infrared thermography, as a full field method, enables evaluation of the whole scanned area. The A-scan, as a point-wise method, does not provide the image of whole area of interest. By combining these two methods, robust and reliable approach to analysis of composite structure is enabled.
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Zhang, Wei, Qi Ke Li, and Zheng Wei Yang. "Numerical Analysis for Thermal Wave NDT of Debonding Defect of Coating on the Matrix of the Composite Materials." Applied Mechanics and Materials 174-177 (May 2012): 1357–62. http://dx.doi.org/10.4028/www.scientific.net/amm.174-177.1357.
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For the disadvantages of the traditional NDT methods for coating defects, Thermal Wave Nondestructive Testing (TWNDT) technology was used to detect coating debonding defect on composite Materials matrix. Numerical simulation method was used to simulate the heat transfer process of thermal wave in the coating material with defects. The factors influencing the testing sensitivity were in-depth studied, including the debonding defect size and coating thickness. Simulation results show that: TWNDT technology can quickly and efficiently identify the size of the coating debonding defects, while the thickness of the coating is an important factor influencing the inspection sensitivity for the thermal wave detection.
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Tavukçuoğlu, Ayşe. "Non-Destructive Testing for Building Diagnostics and Monitoring: Experience Achieved with Case Studies." MATEC Web of Conferences 149 (2018): 01015. http://dx.doi.org/10.1051/matecconf/201814901015.
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Building inspection on site, in other words in-situ examinations of buildings is a troublesome work that necessitates the use of non-destructive investigation (NDT) techniques. One of the main concerns of non-destructive testing studies is to improve in-situ use of NDT techniques for diagnostic and monitoring studies. The quantitative infrared thermography (QIRT) and ultrasonic pulse velocity (UPV) measurements have distinct importance in that regard. The joint use of QIRT and ultrasonic testing allows in-situ evaluation and monitoring of historical structures and contemporary ones in relation to moisture, thermal, materials and structural failures while the buildings themselves remain intact. For instances, those methods are useful for detection of visible and invisible cracks, thermal bridges and damp zones in building materials, components and functional systems as well as for soundness assessment of materials and thermal performance assessment of building components. In addition, those methods are promising for moisture content analyses in materials and monitoring the success of conservation treatments or interventions in structures. The in-situ NDT studies for diagnostic purposes should start with the mapping of decay forms and scanning of building surfaces with infrared images. Quantitative analyses are shaped for data acquisition on site and at laboratory from representative sound and problem areas in structures or laboratory samples. Laboratory analyses are needed to support in-situ examinations and to establish the reference data for better interpretation of in situ data. Advances in laboratory tests using IRT and ultrasonic testing are guiding for in-situ materials investigations based on measurable parameters. The knowledge and experience on QIRT and ultrasonic testing are promising for the innovative studies on today’s materials technologies, building science and conservation/maintenance practices. Such studies demand a multi-disciplinary approach that leads to bring together knowledge on materials science and building science.
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Li, Sheng Shan, Xiao Yan Tong, Lei Jiang Yao, and Bin Li. "Validity of Several NDT Methods on Low Velocity Impact Damage Evaluation of 2-Dimensional Plain Woven C/SiC Composites." Advanced Materials Research 581-582 (October 2012): 764–67. http://dx.doi.org/10.4028/www.scientific.net/amr.581-582.764.
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An experimental study was carried out to study the low-velocity impact characteristics and the influence of impact energy on the damage of plain woven carbon fiber reinforced silicon carbide composite. Visual, ultrasonic scanning, X-ray, industrial CT and infrared thermal imaging were then utilized respectively for Nondestructive Testing of the test specimens after impact test. The results show that the material damage area increase significantly with the increase of the impact energy. But as the specimen is run through, when the impact energy comes to12J, the damage area decrease. Compare the changing curves of the damage areas obtained by different detection methods, we can find that the changing trends of the damage areas obtained by ultrasonic C-scan and infrared thermal imaging are the same with the impact energies, indicating that the damage of the specimen are more credible by the two methods.
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Li, Xiaoyuan, Xiaowei Ying, Wen Zhu, Wei Liu, Beiping Hou, and Le Zhou. "Nondestructive detection and analysis based on data enhanced thermography." Measurement Science and Technology 33, no. 6 (March 24, 2022): 064006. http://dx.doi.org/10.1088/1361-6501/ac5280.
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Abstract Machine learning and data fusion methods have played a significant role in the nondestructive testing (NDT) of composite materials in modern industries. Among them, feature extraction thermography models such as principal component thermography have been well studied and applied due to their advantages of dimensionality reduction and discriminative representation. However, current pulse thermal imaging technology can only collect limited images since the tested materials cannot usually be overheated, which also decreases the performance of the feature extraction thermography models. In this paper, an improved denoising convolutional autoencoder with U-net architecture is proposed for data enhancement purposes. Using the developed structure, enhanced images are generated, in which the deep spatial information in the original images is maintained while measurement noises are decreased simultaneously. Using the original and enhanced images together, the NDT performance based on feature extraction thermography is further improved. Finally, the feasibility and effectiveness of the proposed methods are demonstrated by two defect detection experiments on carbon fiber reinforced polymer.
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Солодов, Igor Solodov, Кройцбрук, and Mark Kreutzbruck. "Resonant Defects: A New Approach to Highly-Sensitive Ultrasound-Activated NDT Techniques." NDT World 19, no. 4 (December 15, 2015): 8–12. http://dx.doi.org/10.12737/23496.
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The presence of a defect leads to a local decrease in rigidity for a certain mass of the material and therefore manifests in a particular characteristic frequency of the defect. A frequency match between the driving ultrasonic wave and this characteristic frequency provides a Local Defect Resonance (LDR) and results in efficient energy delivery from the wave into the defect. In this paper, such a selective ultrasonic activation of resonant defects is suggested to enhance nonlinear ultrasonic, optical and thermal defect responses. Multiple case studies demonstrate that the resonant excitation of a defect results in a high local vibration and enhancement of sensitivity in ultrasonic NDT and imaging of defects via laser vibrometry, thermosonics, nonlinearity and shearography readily measurable even for a few mW of ultrasonic power. The LDR-based NDT methods require much lower ultrasonic power to activate the defects that makes it possible to avoid high- power ultrasonic instrumentation.
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Dong, Guanping, Shanwei Sun, Zixi Wang, Nanshou Wu, Pingnan Huang, Hao Feng, and Minqiang Pan. "Application of machine vision-based NDT technology in ceramic surface defect detection – a review." Materials Testing 64, no. 2 (February 1, 2022): 202–19. http://dx.doi.org/10.1515/mt-2021-2012.
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Abstract For its good mechanical, thermal, and chemical property, ceramic materials are widely used in construction, chemical industry, electric power, communication and other fields. However, due to its particularity and complex production process, quality problems usually occur, of which the most common one is surface defects. For ceramic products, the defects are usually small and complicated, and manual methods are difficult to ensure the accuracy and speed of detection. Relevant researchers have proposed a variety of machine vision-based ceramic defect detection methods, but these methods still need to break through in solving the key problems of ceramic surface glaze reflection, complex detection environment, low algorithm efficiency and low real-time performance. To this end, this article reviews the application status of machine vision on ceramic surface defect detection in recent years, summarizes and analyzes the existing non-destructive testing (NDT) technology method, and points out the main factors that affect the development of ceramic surfaces defect detection technology and puts forward the corresponding solutions.
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Guofeng, Jin, Zhang Wei, Shi Jun, Yang Zhengwei, Hu Yu, Huang Zhiyong, and Tian Gan. "Numerical Analysis of Influencing Factors and Capability for Thermal Wave NDT in Liquid Propellant Tank Corrosion Damage Detection." Measurement Science Review 13, no. 4 (August 1, 2013): 214–22. http://dx.doi.org/10.2478/msr-2013-0033.
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Due to the disadvantages of traditional NDT methods for liquid propellant tank corrosion detection, Thermal Wave Nondestructive Testing (ITWNDT) technology was applied. The heat exchange process of thermal wave in corrosion tank was simulated by the numerical method. Parameters of TWNDT as the best detection time (tbest), the maximum surface temperature difference (ΔTmax), and the temperature difference holding time (τΔT>0.1) were discussed as the targets. Based on these parameters, factors influencing the detection results of tank materials, dressed liquid (also considered as the corrosion product), pit characters (depth and size), heat flux and thermal excitation time length (pulsed width), environmental conditions and other factors were analyzed. Simulation results show that ITWNDT can identify the defect depth, size and position rapidly and effectively. Material properties of the tank were influencing the tbest, ΔTmax and τΔT>0.1, while the dressed liquid, thermal excitation parameters and the conditions of environment do not influence the tbest. Pit characters of the depth and size have close relationship with tbest and ΔTmax, therefore, for a tank with certain material and certain liquid dressed in, the pit corrosion damage can be accurately evaluated.
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Montinaro, Nicola, Mario Fustaino, and Antonio Pantano. "Carbon Nanotubes Dispersion Assessment in Nanocomposites by Means of a Pulsed Thermographic Approach." Materials 13, no. 24 (December 11, 2020): 5649. http://dx.doi.org/10.3390/ma13245649.
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The extensive production of polymer composites reinforced by carbon nanotube is limited by the absence of non-destructive evaluation (NDE) methods capable of assessing product quality to guarantee compliance with specifications. It is well known that the level of dispersion of carbon nanotubes (CNTs) in the polymer matrix is the parameter that, much more than others, can influence their enhancement capabilities. Here an active Infrared Thermography Non Destructive Testing(IR-NDT) inspection, joined with pulsed phase thermography (PPT), were applied for the first time to epoxy-CNT composites to evaluate the level of dispersion of the nanoparticles. The PPT approach was tested on three groups of epoxy nanocomposite samples with different levels of dispersion of the nanoparticles. The phasegrams obtained with the presented technique clearly show clusters, or bundles, of CNTs when present, so a comparison with the reference sample is not necessary to evaluate the quality of the dispersion. Therefore, the new NDE approach can be applied to verify that the expected dispersion levels are met in products made from epoxy and Multi-Walled Carbon Nanotubes (MWCNTs). The mechanisms underlying the effects of the dispersion of carbon nanotube on the thermal response of polymer composites have been identified.
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Groz, Marie-Marthe, Emmanuelle Abisset-Chavanne, Anissa Meziane, Alain Sommier, and Christophe Pradère. "Bayesian Inference for 3D Volumetric Heat Sources Reconstruction from Surfacic IR Imaging." Applied Sciences 10, no. 5 (February 28, 2020): 1607. http://dx.doi.org/10.3390/app10051607.
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The domain of non-destructive testing (NDT) or thermal characterization is currently often done by using contactless methods based on the use of an IR camera to monitor the transient temperature response of a system or sample warmed by using any heat source. Though many techniques use optical excitation (flash lamps, lasers, etc.), some techniques use volumetric sources such as acoustic or induction waves. In this paper, we propose a new inverse processing method, which allows for the estimation of 3D fields of heat sources from surface temperature measurements. This method should be associated with volumetric heat source generation. To validate the method, a volumetric source was generated by the Joule effect in a homogeneous PVC sample using an electrical thin cylindrical wire molded in the material. The inverse processing allows us to retrieve the depth of the wire and its geometrical shape and size. This tool could be a new procedure for retrieving 3D defects on NDT.
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Chulkov, A. O., D. A. Nesteruk, B. I. Shagdyrov, and V. P. Vavilov. "Method and Equipment for Infrared and Ultrasonic Thermographic Testing of Large-Sized Complex-Shaped Composite Products." Russian Journal of Nondestructive Testing 57, no. 7 (July 2021): 619–26. http://dx.doi.org/10.1134/s1061830921070044.
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Abstract The robotic equipment for and the technique of combined thermal nondestructive testing (NDT) of large-sized products by zones with subsequent data synthesis are described. The effectiveness of the combination of two methods, infrared and ultrasonic thermographic testing, is shown by the example of the developed complex-shaped reference sample with 18 simulators of production and operational defects. The developed algorithms for the synthesis of test results, including spatial “matching” of a set of thermograms and automated flaw detection and defect characterization with the use of neural networks have illustrated the effectiveness of the proposed approach for practical application.
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Svobodová, Marie, Ladislav Horvath, Jindřich Douda, Jaromír Shejbal, and Eva Svobodová. "Long-Term Thermal Degradation of Mn-V Steel (W. Nr. 1.1133)." Key Engineering Materials 465 (January 2011): 499–502. http://dx.doi.org/10.4028/www.scientific.net/kem.465.499.
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This paper summarizes the achieved results of microstructure analysis and mechanical testing of long-term degradation of Mn-V steel (W. Nr. 1.1133, ČSN 41 3123) frequently used in small and middle boiler pressure systems operating under creep conditions. In these systems, non-exchangeable components often limit a safety of their service operation. Therefore in view of the monitoring, non-destructive methods like replica technique, hardness testing and defectoscopy, and probabilistic approach to residual life assessment seems to be the only way how to quantitatively determine a residual life of the boiler pressure system. Achieved results of as-exposed and as-secondary aged Mn-V steel confirmed that besides NDT controlling of sheet welds due to possible cracks, the replica technique (on available component surface) accompanied by hardness measurement on each segment of weldment should be sufficient for residual life assessment of thick-walled components of boiler pressure system operating under creep conditions. Additionally as a very rough estimate, a value of limit hardness of steel for safety operation is estimated at about 150 HV.
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Jie, Jing, Shiqing Dai, Beiping Hou, Miao Zhang, and Le Zhou. "Defect Detection in Composite Products Based on Sparse Moving Window Principal Component Thermography." Advances in Polymer Technology 2020 (February 7, 2020): 1–12. http://dx.doi.org/10.1155/2020/4682689.
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As a nondestructive testing (NDT) technology, pulsed thermography (PT) has been widely used in the defect detection of the composite products due to its efficiency and large detection range. To enhance the distinction between defective and defect-free region and eliminate the influence of the measurement noise and nonuniform background of the thermal image generated by PT, a number of thermographic data analysis approaches have been proposed. However, these traditional methods only consider the correlations among the pixel while leave the time series correlations unmodeled. In this paper, a sparse moving window principal component thermography (SMWPCT) method is proposed to incorporate several thermal images using the moving window strategy. Also, the sparse trick is used to provide clearer and more interpretable results because of the structure sparsity. The effectiveness of the method is verified by the defect detection experiment of carbon fiber-reinforced plastic specimens.
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Chaban, Antonina, Vivi Tornari, Rita Deiana, Michalis Andrianakis, David Giovannacci, and Vincent Detalle. "A Combined Non-Invasive Approach to the Study of A Mosaic Model: First Laboratory Experimental Results." Journal of Imaging 5, no. 6 (June 10, 2019): 58. http://dx.doi.org/10.3390/jimaging5060058.
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This paper presents first laboratory results of a combined approach carried out by the use of three different portable non-invasive electromagnetic methods: Digital holographic speckle pattern interferometry (DHSPI), stimulated infrared thermography (SIRT) and holographic subsurface radar (HSR), proposed for the analysis of a custom-built wall mosaic model. The model reproduces a series of defects (e.g., cracks, voids, detachments), simulating common deteriorated, restored or reshuffled areas in wall mosaics. DHSPI and SIRT, already well known in the field of non-destructive (NDT) methods, are full-field contactless techniques, providing complementary information on the subsurface hidden discontinuities. The use of DHSPI, based on optical imaging and interferometry, provides remote control and visualization of surface micro-deformation after induced thermal stress, while the use of SIRT allows visualization of thermal energy diffusion in the surface upon the induced thermal stress. DHSPI and SIRT data are complemented by the use of HSR, a contact method that provides localized information about the distribution of contrasts in dielectric permittivity and related possible anomalies. The experimental results, made by the combined use of these methods to the identification of the known anomalies in the mosaic model, are presented and discussed here as a contribution in the development of an efficient non-invasive approach to the in-situ subsurface analysis of ancient wall mosaics.
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Buyuksahin, Utku, and Ahmet Kirli. "A New Nondestructive Test Equipment Based on Image Processing and Magnetic Flux Analysis." Advanced Materials Research 445 (January 2012): 131–36. http://dx.doi.org/10.4028/www.scientific.net/amr.445.131.
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Nondestructive testing (NDT) methods has been increased within recent years depending on the needs of industry, parallel to new technological developments. Many studies have focused on thermal imagining, magnetic flux analysis or both, which are used in order to detect the deformation on surface and under the surface. In this study a new technique is suggested to eliminate the perturbations which are distorting effects of one point cameras in terms of perspective. A new integration is also proposed in this research such as using image recognition with magnetic flux analysis. Taking advantage of this integration and the new approach to image processing, both the surface and the inside of a mechanical product can be tested properly.
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Yao, Wenqing, Fuwei Sheng, Xiaoyuan Wei, Lei Zhang, and Yuan Yang. "Propagation characteristics of ultrasonic guided waves in continuously welded rail." Modern Physics Letters B 31, no. 19-21 (July 27, 2017): 1740075. http://dx.doi.org/10.1142/s0217984917400759.
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Rail defects cause numerous railway accidents. Trains are derailed and serious consequences often occur. Compared to traditional bulk wave testing, ultrasonic guided waves (UGWs) can provide larger monitoring ranges and complete coverage of the waveguide cross-section. These advantages are of significant importance for the non-destructive testing (NDT) of the continuously welded rail, and the technique is therefore widely used in high-speed railways. UGWs in continuous welded rail (CWR) and their propagation characteristics have been discussed in this paper. Finite element methods (FEMs) were used to accomplish a vibration modal analysis, which is extended by a subsequent dispersion analysis. Wave structure features were illustrated by displacement profiles. It was concluded that guided waves have the ability to detect defects in the rail via choice of proper mode and frequency. Additionally, thermal conduction that is caused by temperature variation in the rail is added into modeling and simulation. The results indicated that unbalanced thermal distribution may lead to the attenuation of UGWs in the rail.
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Szczepankowski, Andrzej, Radoslaw Przysowa, Jerzy Perczyński, and Artur Kułaszka. "Health and Durability of Protective and Thermal Barrier Coatings Monitored in Service by Visual Inspection." Coatings 12, no. 5 (May 3, 2022): 624. http://dx.doi.org/10.3390/coatings12050624.
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Protective and Thermal Barrier Coatings (TBC) applied on gas-turbine blades gradually degrade due to oxidation, aluminum depletion and impacts of environmental particles. Among various non-destructive coating testing methods (NDT), visual inspection can be undertaken regularly in service, but it provides little quantitative information, and only surface defects can be detected. This work aims at in-service monitoring of turbine blades with multilayer coatings applied by atmospheric plasma spraying (APS) in a few variants. They were validated during a series of accelerated mission tests of a retired military turbofan engine in a test cell together with five other technologies. The fifty-hour rainbow test focused on assessing coating durability. Between engine runs, 12 borescope inspections were conducted to monitor the health of the blades. Finally, the blades were disassembled and examined using computed tomography (CT) and metallographic methods. Throughout the testing, 31 newly-coated blades (66%) withstood the tests, producing results comparable to the reference blades. However, 16 blades suffered intolerable failures observed as increased roughness, gradual loss of the topcoat, spallation and minor foreign object damage. Visual inspection results were generally in agreement with subsequent laboratory tests.
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Drobiec, Łukasz, Rafał Wyczółkowski, and Artur Kisiołek. "Numerical Modelling of Thermal Insulation of Reinforced Concrete Ceilings with Complex Cross-Sections." Applied Sciences 10, no. 8 (April 11, 2020): 2642. http://dx.doi.org/10.3390/app10082642.
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The article describes the results of numerical analyses and traditional calculations of the heat transfer coefficient in ceilings with a complex cross-section, and with materials of varying density built-in inside the cross-section. Prefabricated prestressed reinforced concrete, composite reinforced, and ribbed reinforced concrete ceilings were analyzed. Traditional calculations were carried out in accordance with the EN ISO 6946:2017 standard, while the numerical analyses were carried out in a program based on the finite element method (FEM). It has been shown that calculations can be a good alternative to nondestructive testing (NDT) and laboratory tests, whose use in the case of ceilings with different geometries is limited. The differences between the calculations carried out in accordance with EN ISO 6946:2017, and the results of numerical analyses are 12%–39%. The way the air voids are taken into account has an impact on the calculation results. In the traditional method, an equivalent thermal conductivity coefficient was used, while in the numerical analysis, the coefficient was selected from the program’s material database. Since traditional calculations require simplifications, numerical methods should be considered to give more accurate results.
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Tyralla, Dieter, and Thomas Seefeld. "Thermal Based Process Monitoring for Laser Powder Bed Fusion (LPBF)." Advanced Materials Research 1161 (March 2021): 123–30. http://dx.doi.org/10.4028/www.scientific.net/amr.1161.123.
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Laser powder bed fusion (LPBF) is a frequently used manufacturing process due to its advantages in lightweight construction, design possibilities and functionalization of geometry. However, the printed parts will often have to undergo time and cost expensive non-destructive testing by sophisticated methods like X-CT. Thus, there is a strong demand to identify suitable online process monitoring techniques that allow to reduce or substitute post-process NDT effort. The temperature field reacts sensitively to deviations during processing, thus online temperature monitoring is a promising approach. In the present work a spatially resolved temperature measurement, based on 2-channel-pyrometry, is used for process monitoring in LPBF. The camera system is coaxially integrated into the beam guidance of the LPBF system. The coaxial observation enables a lateral resolution better than 10 μm over the whole build-up area of 250 x 250 mm2. Single tracks were welded with different parameters and observed by the camera system to identify thermal indicators. Metallographic cross-sections of the tracks were compared with the melt pool width measured by the online observation system. The deviation was ca. 3 %. In addition, cubes of 10 mm by 10 mm by 10 mm are built up. The melt pool area is identified as useful indicator for the process behavior and for the first time the assessment of part density is demonstrated in LPBF during process by the help of a thermal monitoring system.
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Zielińska, Monika, and Magdalena Rucka. "Non-destructive Testing of Wooden Elements." IOP Conference Series: Materials Science and Engineering 1203, no. 3 (November 1, 2021): 032058. http://dx.doi.org/10.1088/1757-899x/1203/3/032058.
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Abstract Examining the condition of wooden elements is crucial from the perspective of proper structure performance. If the deterioration in the internal wood condition, which displays no symptoms visible from the outside, is detected, the further spread of the deterioration can be prevented. Test results often point to the necessity of conducting repairs and, renovations, replacing the structure of wooden beams, or even substituting a significant part of the structure. To achieve acceptable results, test methods should take into account the anisotropic nature of wood, which includes the shape of annual rings, as well as the location of the core in crosssection. To adopt methods based on physical effects, profound knowledge of wood physics is needed, particularly of interdependence. Apart from simple tests such as a visual inspection or tapping that are used to determine near-surface defects, non-destructive testing (NDT) plays an important role in the process. This paper presents the methods of non-destructive testing of wooden elements. These methods include tests conducted with ground penetrating radar (GPR), thermal techniques, microwaves, acoustic emission, ultrasonic tomography, and X-ray tomography. The paper summarises the use of non-destructive methods, indicating their advantages, disadvantages as well as some limitations.
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Dychtoń, Kamil, Andrzej Gradzik, Łukasz Kolek, and Krzysztof Raga. "Evaluation of Thermal Damage Impact on Microstructure and Properties of Carburized AISI 9310 Gear Steel Grade by Destructive and Non-Destructive Testing Methods." Materials 14, no. 18 (September 14, 2021): 5276. http://dx.doi.org/10.3390/ma14185276.
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Advanced aircraft gearboxes operate under high mechanical loads. Currently, aircraft gears are manufactured from chromium–nickel–molybdenum steel grades such as AISI 9310 or Pyrowear 53. The major causes of gear failure are wear and fatigue cracking. As the crack initiation occurs predominantly on the component surface, the gears are routinely subjected to surface hardening processes such as low-pressure carburizing and case hardening. The gears are manufactured in a multiple operation process, in which teeth grinding is a crucial step. Selection of improper grinding conditions can lead to local heat concentration and creation of grinding burns, which are small areas where microstructure and properties changes are induced by high temperature generated during grinding. Their presence can lead to significant reduction of gear durability. Therefore destructive and non-destructive (NDT) quality-control methods such as chemical etching or magnetic Barkhausen noise (MBN) measurements are applied to detect the grinding burns. In the area of a grinding burn, effects related to the over-tempering or re-hardening of the carburized case may occur. In this paper, the results of the studies on the characterization of microstructure changes caused by local heating performed to simulate grinding burns are presented. The areas with the over-tempering and re-hardening effects typical for grinding burns were formed by laser surface heating of carburized AISI 9310 steel. Analyses of the microstructure, residual stresses, retained austenite content, and non-destructive testing by the MBN method were performed. The correlation between the MBN value and the properties of the modified surface layer was identified. It was also found that the re-hardened areas had similar characteristics of changes in the Barkhausen noise intensity, despite the significant differences in the width of the overheated zone, which depended on the laser-heating process conditions.
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Fenn, R., and J. C. Watson. "Remote edge detection of subcutaneous stiffeners." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 219, no. 8 (August 1, 2005): 579–85. http://dx.doi.org/10.1243/095440505x32490.
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Construction of narrow-gap double skin components requires, at some stage, blind welding from one side. During construction, due to thermal distortion, the hidden stiffeners (spacers or stringers) may move sufficiently far from their designated locations that assembly welds, made from one side, could miss the stringers completely. Thus, a real-time sensor capable of identifying and accurately locating spacer edges beneath the outer skin is required. Outer skin magnetic properties and plate/spacer separation seriously influence the capabilities of the best candidate detecting methods. Initial trials were undertaken using a non-destructive testing (NDT) eddy current method to detect beneath aluminium plate. Probe design and construction concentrated on air-cored absolute coils, on which finite element analysis (FEA) was used to predict electrical response. When the refined detector system was tested on magnetic material (mild steel), it was found to be preferable if a static magnetic field was applied to the plate component. Applied magnetism had a profound effect on coil field penetration and hence detectability (maximum plate thickness rose swiftly from 3mm, unmagnetized, to over 12mm, magnetized). As a sensor, the eddy current detector was shown to be capable of finding subcutaneous edges in both aluminium and mild steel fabrications. What has been developed is a sensor simply requiring computer-controlled movement to allow completely automatic hidden edge finding.
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Cruz-Gómez, Alejandro, A. Alondra Castro Campillo, Zamira A. Ávila-Valle, Livia León-Paniagua, Marcia Ramírez-Sánchez, and José Ramírez-Pulido. "Rejection of the monotypic status of Peromyscus furvus (Rodentia: Cricetidae), with consequences for its species group." Therya 12, no. 2 (May 30, 2021): 347–67. http://dx.doi.org/10.12933/therya-21-1122.
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Previous studies using Cytochrome-b or ND3-ND4 mitochondrial gene have yielded intriguing evidence about the phylogenetic relationships among populations of Peromyscus furvus; however, those studies each based on phylogenies for a single type of genes, yielded conflicting topologies. In addition, analyses with traditional morphometrics have revealed differences in skull size among certain populations of the species. Therefore, in order to reassess the systematic and taxonomic status of P. furvus, we incorporated a suite of genetic and morphometric characters and employed cladistic analyses. Herein, we present results mostly derived from our genetic analyses (results from the phylogenetic examination of skull size and shape will appear later). Phylogenetic analyses were conducted using four mitochondrial genes (Cytb and ND3-ND4L-ND4) with the respective data analyzed separately or combined, followed by an analysis with genetic and morphometric data (size and shape characters). Most phylogenetic constructions were made with parsimonious methods, but probabilistic methods also were used in the analyses with the genes separated by type. Similar topologies were recovered from all analyses of the Cytb gene and from all parsimony analyses of the NADH genes; however, conflicting topologies were obtained with the probabilistic methods for the NADH genes. Additionally, to better understand the genetic variation in each type of gene, analyses for genetic divergence were conducted within and among genetic groups and haplotype networks were constructed. All the topologies obtained using genetic data questioned the monotypic status of P. furvus, as two additional clades were identified that seemingly correspond to unrecognized entities. The first of these, P. latirostris, occurs in the northern region and could be considered as either a species or subspecies. An unknown Peromyscus species nova that occurs to the south is considered as a valid species. Further, P. furvus s. s. becomes a polytypic species by recognizing at least two subspecies (P. f. angustirostris and P. f. furvus). Phylogenetic analyses also rejected membership of P. melanocarpus and P. ochraventer within the furvus species group. Instead, P. melanocarpus showed a greater affinity to P. mexicanus totontepecus, whereas, P. ochraventer either joined to the clade containing P. melanocarpus and P. m. tototepecus or to Megadontomys cryophilus in a sister clade. Finally, Osgoodomys banderanus (subgenus Haplomylomys) always remained basally positioned and segregated from all members of the subgenus Peromyscus.
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Ellingson, W. A., S. A. Rothermel, and J. F. Simpson. "Nondestructive Characterization of Ceramic Composites Used as Combustor Liners in Advanced Gas Turbines." Journal of Engineering for Gas Turbines and Power 118, no. 3 (July 1, 1996): 486–90. http://dx.doi.org/10.1115/1.2816672.
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Nondestructive characterization (NDC) methods, which can provide full-field information about components prior to and during use, are critical to the reliable application of continuous fiber ceramic matrix composites in high-firing-temperature (>1350°C) gas turbines. [For combustor liners, although they are nonmechanical load-bearing components, both thermal characteristics and mechanical integrity are vitally important.] NDC methods being developed to provide necessary information include x-ray computed tomography (mainly for through-wall density and delamination detection), infrared-based thermal diffusivity imaging, and single-wall through-transmission x-ray imaging (mainly for fiber content and alignment detection). Correlation of the data obtained from NDC methods with subscale combustor liner tests have shown positive results at thermal cycling temperatures from 700°C to 1177°C.
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Opsal, Jon, and Allan Rosencwaig. "Physics of Thermal Wave NDE of Semiconductor Materials and Devices." MRS Bulletin 13, no. 4 (April 1988): 28–33. http://dx.doi.org/10.1557/s0883769400065866.
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Thermal wave physics is playing an ever increasing role in the on-line characterization of semiconductor materials and devices. This is especially true for thermal wave methods that employ laser beams for both the generation and detection of thermal waves. For the modulated reflectance method discussed here, the pump and probe beams are focused on the same spot. They therefore achieve the noncontact advantage of optical methods in addition to the optimum condition for high spatial resolution, a necessary condition for thermal wave measurements on product wafers.When a material is excited with an intensity-modulated laser beam or pump, a thermal wave is generated in the material and in the air above the sample. The material within this heated region will undergo a thermal expansion which can be detected with a probe beam interferometer or by deflecting the probe beam from the thermoelastic deformation of the surface. Since the complex refractive index of most materials depends on temperature, a modulated temperature will also induce a corresponding modulation in the refractive index and consequently a modulation on a probe beam passing anywhere near the thermal wave. A probe beam directed along the heated surface of the sample, for example, will be deflected as it passes through the heated region above the surface. This mirage effect can also be observed within the sample by directing a transmitting probe through the heated region beneath the surface. Likewise, using a probe beam directed onto the sample surface one can observe a modulation in reflection, transmission, or scattering. A related noncontact method is the photothermal measurement of infrared radiation emitted from the material's heated region. Note that with all these detection methods, thermal wave measurements can be, and most often are, done in air and at room temperature.
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Pan, Yang, Luyao Long, Daitao Zhang, Tingting Yuan, Shujuan Cui, Peng Yang, Quanyi Wang, and Simei Ren. "Potential False-Negative Nucleic Acid Testing Results for Severe Acute Respiratory Syndrome Coronavirus 2 from Thermal Inactivation of Samples with Low Viral Loads." Clinical Chemistry 66, no. 6 (May 15, 2020): 794–801. http://dx.doi.org/10.1093/clinchem/hvaa091.
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Abstract Background Coronavirus disease-2019 (COVID-19) has spread widely throughout the world since the end of 2019. Nucleic acid testing (NAT) has played an important role in patient diagnosis and management of COVID-19. In some circumstances, thermal inactivation at 56°C has been recommended to inactivate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) before NAT. However, this procedure could theoretically disrupt nucleic acid integrity of this single-stranded RNA virus and cause false negatives in real-time polymerase chain reaction (RT-PCR) tests. Methods We investigated whether thermal inactivation could affect the results of viral NAT. We examined the effects of thermal inactivation on the quantitative RT-PCR results of SARS-CoV-2, particularly with regard to the rates of false-negative results for specimens carrying low viral loads. We additionally investigated the effects of different specimen types, sample preservation times, and a chemical inactivation approach on NAT. Results Our study showed increased Ct values in specimens from diagnosed COVID-19 patients in RT-PCR tests after thermal incubation. Moreover, about half of the weak-positive samples (7 of 15 samples, 46.7%) were RT-PCR negative after heat inactivation in at least one parallel testing. The use of guanidinium-based lysis for preservation of these specimens had a smaller impact on RT-PCR results with fewer false negatives (2 of 15 samples, 13.3%) and significantly less increase in Ct values than heat inactivation. Conclusion Thermal inactivation adversely affected the efficiency of RT-PCR for SARS-CoV-2 detection. Given the limited applicability associated with chemical inactivators, other approaches to ensure the overall protection of laboratory personnel need consideration.
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Srinivas, V. Karthik, and A. K. Lakshminarayanan. "On the Local Constitutive Behavior of Friction Stir Welded AISI 304 Stainless Steel Joints." Materials Science Forum 979 (March 2020): 107–13. http://dx.doi.org/10.4028/www.scientific.net/msf.979.107.
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The uniaxial tensile test is often used to determine the mechanical properties of a material like its yield strength and elastic limit. However, some of the recent advances in imaging Non Destructive Evaluation (NDE) modalities offer experimental tools which, apart from determining the conventional properties, also make it possible to visualise and map the dynamic strain evolution during monotonic loading and correlate it with the micro mechanisms of deformation. Infrared thermal imaging (IRT) and digital image correlation (DIC) are two such advanced NDE methods which are being widely used in experimental mechanics. Infrared thermal imaging maps the thermal gradient including the dynamic thermal transients that may occur during the tensile testing and is based on the detection of infrared radiation. Digital image correlation, a non-contact optical method based on grey value correlation before and after deformation, maps the magnitude of deformation on the surface of the object under load. In this investigation, the global and local properties of a friction stir welded joint of 304 Austenitic Stainless steel through the simultaneous application of thermal imaging and digital image correlation. By characterising the various stages of tensile deformation, this study enabled correlation of the thermal and strain evolutions and to provide deeper insights into the micro-mechanisms of the associated deformation phenomenon.
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Qin, Shaoyong, Jinghong Song, Wuxiao Wang, Bingchu Mei, Weiwei Li, and Yuanming Xia. "Study in Optical and Mechanical Properties of Nd3+, Y3+: SrF2 Transparent Ceramics Prepared by Hot-Pressing and Hot-Forming Techniques." Crystals 9, no. 12 (November 26, 2019): 619. http://dx.doi.org/10.3390/cryst9120619.
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Nd3+, Y3+: SrF2 transparent ceramics were successfully synthesized by two methods: hot-forming and hot-pressing techniques. The mechanical properties and optical properties of the hot-formed Nd3+, Y3+: SrF2 transparent ceramics were much better than that of single crystal. On the other hand, the transmittance of the hot-formed transparent ceramics with different deformation rate reached up to 90% at 1054 nm, which is superior to the hot-pressed ceramics. Furthermore, the fracture toughness of hot-formed Nd3+, Y3+: SrF2 transparent ceramics with the deformation rate of 51% reached up to 0.70 MPa m1/2, which is nearly 1.5 times higher than that of as-grown single crystal. The full width at half maximum (FWHM) of the hot-formed ceramic is larger than that of the single crystal at 1053 nm under continuous-wave (CW) laser operation. The thermal conductivity of Nd3+, Y3+: SrF2 single crystal and hot-formed ceramics were also discussed.
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Meng, Dewei, Shibin Lin, and Hoda Azari. "Reducing Thermal Reflections for Infrared Thermography Applications on Tunnel Liners with Reflective Finishes." Transportation Research Record: Journal of the Transportation Research Board 2672, no. 41 (June 20, 2018): 145–55. http://dx.doi.org/10.1177/0361198118780711.
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Infrared thermography (IRT) has been employed as a non-destructive evaluation (NDE) method to detect delaminations in bridge decks by ASTM standards since 2003. Compared to other NDE methods, IRT is fast in data acquisition and processing. In addition to applications on bridge decks, IRT can be employed to detect defects in other structures such as roadway pavements and tunnel liners. Recent IRT applications on tunnel liners with reflective finishes such as ceramic tiles show that the IRT results can be severely contaminated by infrared reflections of the vehicles and the illuminating systems in the tunnels. In this study, an algorithm is developed to mitigate the contamination caused by the thermal reflections in the IRT results. The reflection is reduced by combining thermal data from multiple thermographs. Perspective projection is employed to map thermal data to the same coordinates if the thermographs are taken with an infrared camera moving in the space. The algorithm is proved to be successful by the results from the lab experiments and field tests. The algorithm can work with IRT data collected by vehicle-mounted infrared cameras to achieve high-speed IRT for tunnel liners with reflective finishes.
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Lutterschmidt, William I., and Victor H. Hutchison. "The critical thermal maximum: history and critique." Canadian Journal of Zoology 75, no. 10 (October 1, 1997): 1561–74. http://dx.doi.org/10.1139/z97-783.
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We reviewed 725 papers published since Cowles and Bogert's paper on thermal tolerance (R.B. Cowles and C.M. Bogert. 1944. Bull. Am. Mus. Nat. Hist. 83: 261–296) to create a data base of studies that used critical thermal maximum or lethal-temperature methods. We found data from 388 of these papers to provide a historical and taxonomic review of various methodologies used in measuring tolerance of high temperature. We conducted this literature review of previous studies to (i) describe the history of the study of thermal tolerance and show the chronological trends in the use of lethal temperature and critical thermal maximum methods, (ii) illustrate the diversity of taxa used in thermal-tolerance studies, (iii) summarize the diversity of protocols (i.e., end points, heating rates, acclimations, etc.) used for determining thermal tolerance, (iv) provide physiological reasons why the onset of spasms is more meaningful biologically than the loss of righting response, and (v) discuss the difficulties in using data from studies in which widely divergent methods were used and the importance of obtaining comparative thermal-tolerance data for comparative physiology. The adoption of the onset of spasms as a standard end point would allow for valid comparisons of data from different studies and among taxa, an important consideration for current investigations of comparative physiology that use the comparative phylogenetic method.
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Qi, Xiaoding, Masood Soorie, Zainovia Lockman, and Judith L. MacManus-Driscoll. "Rapid Growth of Nd2−xCexCuO4 Thick Films as a Buffer for the Growth of Rare-earth Barium Cuprate–coated Conductors." Journal of Materials Research 17, no. 1 (January 2002): 1–4. http://dx.doi.org/10.1557/jmr.2002.0001.
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Nd2−xCexCuO4 (x = 0 to 0.15) thick films were grown directly on LaAlO3 substrates and surface-oxidized Ni tapes by fast liquid-phase processing methods. The films had a smooth surface and a very good biaxial texture, with the full width at halfmaximum equal to 0.8° and 5° on LaAlO3 substrates and surface-oxidized Ni tapes, respectively. Films of thickness of 5–15 μmm were grown at rates in excess of 2 μm/min. Nd2−xCexCuO4 has a good lattice and thermal-expansion match to rare-earth Ba2Cu3O7−δ (REBCO), minimum reaction with the high-temperature CuO:BaO solutions, and is nonpoisoning to superconductivity. It is an ideal buffer for liquidphase expitaxy processing of REBCO thick films.
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Iglesias, Isabel, José A. Huidobro, Belén F. Alfonso, Camino Trobajo, Aránzazu Espina, Rafael Mendoza, and José R. García. "Kinetic Analysis of the Thermal Decomposition of Iron(III) Phosphates: Fe(NH3)2PO4 and Fe(ND3)2PO4." International Journal of Molecular Sciences 21, no. 3 (January 25, 2020): 781. http://dx.doi.org/10.3390/ijms21030781.
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The hydrothermal synthesis and both the chemical and structural characterization of a diamin iron phosphate are reported. A new synthetic route, by using n-butylammonium dihydrogen phosphate as a precursor, leads to the largest crystals described thus far for this compound. Its crystal structure is determined from single-crystal X-ray diffraction data. It crystallizes in the orthorhombic system (Pnma space group, a = 10.1116(2) Å, b = 6.3652(1) Å, c = 7.5691(1) Å, Z = 4) at room temperature and, below 220 K, changes towards the monoclinic system P21/n, space group. The in situ powder X-ray thermo-diffraction monitoring for the compound, between room temperature and 1100 K, is also included. Thermal analysis shows that the solid is stable up to ca. 440 K. The kinetic analysis of thermal decomposition (hydrogenated and deuterated forms) is performed by using the isoconversional methods of Vyazovkin and a modified version of Friedman. Similar values for the kinetic parameters are achieved by both methods and they are checked by comparing experimental and calculated conversion curves.
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Romanishkin, I. D., D. V. Pominova, P. V. Grachev, V. I. Makarov, A. S. Vanetsev, E. O. Orlovskaya, A. E. Baranchikov, et al. "NONINVASIVE ESTIMATION OF THE LOCAL TEMPERATURE OF BIOTISSUES HEATING UNDER THE ACTION OF LASER IRRADIATION FROM THE LUMINESCENCE SPECTRA OF Nd3+ IONS." Biomedical Photonics 7, no. 2 (June 25, 2018): 25–36. http://dx.doi.org/10.24931/2413-9432-2018-7-2-25-36.
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Laser hyperthermia is one of the promising methods for treatment of oncological diseases. For routine clinical use of hyperthermia, it is necessary to control the uniformity and localization of heat within the tumor. Local heating can be achieved by using special thermal agents, such as nanoparticles doped with rare-earth ions. Measurement of the temperature of the thermal agents will allow timely regulation of the applied laser radiation excitation power and optimization of the hyperthermia process.The paper presents the results of a study on the non-invasive determination of the YPO4 nanoparticles doped with Nd3+ temperature with sensitivity of 0.2% °С-1 in 30-60°С temperature range. The temperature of the nanoparticles was calculated from the Nd3+ luminescence spectra in the 800-1000 nm range under excitation into 4F5/2 energy state by 805 nm laser. A calibration procedure for recalculating the ratio of the luminescence intensities from the Stark sublevels of the 4F3/2 Nd3+ state into the values of the real NP temperature in accordance with the Boltzmann distribution is given. An algorithm for calculating luminescence intensities for individual Stark components is proposed. After calculating the intensities corresponding to each individual Stark component, all the intensities related to the transition from the upper and lower Stark sublevels of the 4F3/2 state are summed, and then their ratio is calculated. The resulting ratio is normalized to the value of the ratio at room temperature and, in accordance with the calibration dependence, is recalculated into the NP heating temperature. It was demonstrated that the investigated 1%Nd3+:YPO4 nanoparticles can be used as "primary” thermometers that do not require additional recalibration to evaluate the temperature in the range used for hyperthermia.
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Chatterjea, Devavani, Luisa Paredes, Tijana Martinov, Evelyn Balsells, Juliann Allen, Akilah Sykes, and Alyssa Ashbaugh. "TNF-alpha neutralizing antibody blocks thermal sensitivity induced by compound 48/80-provoked mast cell degranulation." F1000Research 2 (August 21, 2013): 178. http://dx.doi.org/10.12688/f1000research.2-178.v1.
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Background: Neuro-inflammatory circuits in the tissue regulate the complex pathophysiology of pain. Protective nociceptive pain serves as an early warning system against noxious environmental stimuli. Tissue-resident mast cells orchestrate the increased thermal sensitivity following injection of basic secretagogue compound 48/80 in the hind paw tissues of ND4 mice. Here we investigated the effects of pre-treatment with TNF-α neutralizing antibody on compound 48/80-provoked thermal hyperalgesia. Methods: We treated ND4 Swiss male mice with intravenous anti-TNF-α antibody or vehicle 30 minutes prior to bilateral, intra-plantar compound 48/80 administration and measured changes in the timing of hind paw withdrawal observed subsequent to mice being placed on a 51oC hotplate. We also assessed changes in tissue swelling, TNF-α gene expression and protein abundance, mast cell degranulation, and neutrophil influx in the hind paw tissue. Findings: We found that TNF-α neutralization significantly blocked thermal hyperalgesia, and reduced early tissue swelling. TNF-α neutralization had no significant effect on mast cell degranulation or neutrophil influx into the tissue, however. Moreover, no changes in TNF-α protein or mRNA levels were detected within 3 hours of administration of compound 48/80. Interpretation: The neutralizing antibodies likely target pre-formed TNF-α including that stored in the granules of tissue-resident mast cells. Pre-formed TNF-α, released upon degranulation, has immediate effects on nociceptive signaling prior to the induction of neutrophil influx. These direct effects on nociceptors are abrogated by TNF-α blockade resulting in compromised nociceptive withdrawal responses to acute, harmful environmental stimuli.
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Schulz, Uwe, Wolfgang A. Kaysser, Markus Sips, and Peter Kaul. "Impedance spectroscopy of thermal barrier coatings as non-destructive evaluation tool for failure detection." International Journal of Materials Research 96, no. 7 (July 1, 2005): 725–30. http://dx.doi.org/10.1515/ijmr-2005-0127.
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Abstract Since thermal barrier coatings (TBCs) for turbine blades suffer from bond coat oxidation and sintering of the ceramic top coat during service, quantification of TBC degradation by non destructive evaluation methods (NDE) is essential. IN617 substrates with standard NiCoCrAlY/PYSZ EBPVD TBCs were annealed at 1100 °C and measured by impedance spectroscopy. Parameters such as phase angle, total impedance, real and imaginary part were analyzed. To clearly separate bond coat oxidation from aging of the zirconia, freestanding ceramic top coats and ceramic free samples were analyzed as well. A straight correlation between the changes in the impedance spectra and the measured thickness of the thermally grown oxide was found.
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Song, Liang, Shanjun Liu, and Wenwen Li. "Quantitative Inversion of Fixed Carbon Content in Coal Gangue by Thermal Infrared Spectral Data." Energies 12, no. 9 (May 1, 2019): 1659. http://dx.doi.org/10.3390/en12091659.
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Fixed carbon content is an important factor in measuring the carbon content of gangue, which is important for monitoring the spontaneous combustion of gangue and reusing coal gangue resources. Although traditional measurement methods of fixed carbon content, such as chemical tests, can achieve high accuracy, meeting the actual needs of mines via these tests is difficult because the measurement process is time consuming and costly and requires professional input. In this paper, we obtained the thermal infrared spectrum of coal gangue and developed a new spectral index to achieve the automated quantification of fixed carbon content. Thermal infrared spectroscopy analyses of 42 gangue and three coal samples were performed using a Turbo FT thermal infrared spectrometer. Then, the ratio index (RI), difference index (DI) and normalized difference index (NDI) were defined based on the spectral characteristics. The correlation coefficient between the spectral index and the thermal infrared spectrum was calculated, and a regression model was established by selecting the optimal spectral DI. The model prediction results were verified by a ten times 5-fold cross-validation method. The results showed that the mean error of the proposed method is 5.00%, and the root mean square error is 6.70. For comparison, the fixed carbon content was further predicted by another four methods, according to the spectral depth H, spectral area A, the random forest and support vector machine algorithms. The predicted accuracy calculated by the proposed method was the best among the five methods. Therefore, this model can be applied to predict the fixed carbon content of coal gangue in coal mines and can help guide mine safety and environmental protection, and it presents the advantages of being economic, rapid and efficient.
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Yazdani, Nur, Eyosias Beneberu, and Mina Riad. "Nondestructive Evaluation of FRP-Concrete Interface Bond due to Surface Defects." Advances in Civil Engineering 2019 (January 3, 2019): 1–10. http://dx.doi.org/10.1155/2019/2563079.
Full textAbstract:
Carbon fiber-reinforced polymer (CFRP) laminates have been successfully used as externally bonded reinforcements for retrofitting, strengthening, and confinement of concrete structures. The adequacy of the CFRP-concrete bonding largely depends on the bond quality and integrity. The bond quality may be compromised during the CFRP installation process due to various factors. In this study, the effect of four such construction-related factors was assessed through nondestructive evaluation (NDE) methods, and quantification of the levels of CFRP debonding was achieved. The factors were surface cleanliness, surface wetness, upward vs. downward application, and surface voids. A common unidirectional CFRP was applied to small-scale concrete samples with factorial combinations. Ground-penetrating radar and thermography NDE methods were applied to detect possible disbonds at CFRP-concrete interfaces. Thermography was found to clearly detect all four factors, while the GPR was only effective for detecting the surface voids only. The thermal images overpredicted the amount of debonded CFRP areas by about 25%, possibly due to scaling errors between the thermograph and the sample surface. The maximum debonded CFRP area in any sample was about two percent of the total CFRP area. This is a negligible amount of debonding, showing that the factors considered are unlikely to significantly affect the laminate performance or any CFRP contribution to the concrete member strength or confinement.
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Zhong, Kai. "Laser Performance of Neodymium- and Erbium-Doped GYSGG Crystals." Crystals 9, no. 4 (April 24, 2019): 220. http://dx.doi.org/10.3390/cryst9040220.
Full textAbstract:
Garnet crystals possess many properties that are desirable in laser host materials, e.g., they are suitable for diode laser (LD) pumping, stable, hard, optically isotropic, and have good thermal conductivity, permitting laser operation at high average power levels. Recently, a new garnet material, GYSGG, was developed by replacing some of the yttrium ions (Y3+) with gadolinium ions (Gd3+) in YSGG, demonstrating great potential as a laser host material. GYSGG crystals doped with trivalent neodymium ion (Nd3+) and erbium ions (Er3+) were successfully grown for laser generation in the near- and mid-infrared range, with some of the laser performances reaching the level of mature laser gain media. This paper gives an overview of the achievements made in Nd3+- and Er3+-doped GYSGG lasers at different wavelength ranges. Additionally, full descriptions on Q-switching, mode-locking and wavelength-selecting methods for Nd:GYSGG, and the mechanisms of power scaling by co-doping sensitizers and deactivators in Er:GYSGG, are given. It is expected that this review will help researchers from related areas to quickly gain an understanding of these laser materials and promotes their commercialization and applications.
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Mishra, A. P., H. Purwar, Rajendra K. Jain, and S. K. Gupta. "Microwave Synthesis, Spectral, Thermal and Antimicrobial Studies of Some Co(II), Ni(II) and Cu(II) Complexes Containing 2-Aminothiazole Moiety." E-Journal of Chemistry 9, no. 4 (2012): 1655–66. http://dx.doi.org/10.1155/2012/106460.
Full textAbstract:
Some new Schiff base metal complexes of Co(II), Ni(II) and Cu(II) derived from 4-chlorobenzylidene-2-aminothiazole (CAT) and 2-nitrobenzylidene-2-aminothiazole (NAT) have been synthesized by conventional as well as microwave methods. These compounds have been characterized by elemental analysis, FT-IR, FAB-mass, molar conductance, electronic spectra, ESR, magnetic susceptibility, thermal, electrical conductivity and XRD analysis. The complexes are coloured and stable in air. Analytical data revealed that all the complexes exhibited 1:2 (metal:ligand) ratio with coordination number 4 or 6. FAB-mass and thermal data show degradation pattern of the complexes. The thermal behavior of metal complexes shows that the hydrated complexes loses water molecules of hydration in the first step; followed by decomposition of ligand molecules in the subsequent steps. The crystal system, lattice parameter, unit cell volume and number of molecules in unit cell in the lattice of complexes have been determined by XRD analysis. XRD patterns indicate crystalline nature for the complexes. The solid state electrical conductivity of the metal complexes has also been measured. Solid state electrical conductivity studies reflect semiconducting nature of the complexes. The Schiff base and metal complexes show a good activity against the Gram-positive bacteria;Staphylococcus aureusand Gram-negative bacteria;Escherichia coliand fungiAspergillus nigerandCandida albicans.
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Dutheil, Frédéric, Elodie Chaplais, Audrey Vilmant, Denise Lanoir, Daniel Courteix, Pascale Duche, Armand Abergel, et al. "Effects of a short residential thermal spa program to prevent work-related stress/burnout on stress biomarkers: the ThermStress proof of concept study." Journal of International Medical Research 47, no. 10 (September 11, 2019): 5130–45. http://dx.doi.org/10.1177/0300060519859119.
Full textAbstract:
Objective Work-related stress is a public health issue. Stress has multiple physical and psychological consequences, the most serious of which are increased mortality and cardiovascular morbidity. The ThermStress protocol was designed to offer a short residential thermal spa program for work-related stress prevention that is compatible with a professional context. Methods Participants will be 56 male and female workers aged 18 years or above. All participants will undergo a 6-day residential spa program comprising psychological intervention, physical activity, thermal spa treatment, health education, eating disorder therapy and a follow-up. On six occasions, participants’ heart rate variability, cardiac remodelling and function, electrodermal activity, blood markers, anthropometry and body composition, psychology and quality of life will be measured using questionnaires and bone parameters. Results This study protocol reports the planned and ongoing research for this intervention. Discussion The ThermStress protocol has been approved by an institutional ethics committee (ANSM: 2016 A02082 49). It is expected that this proof of concept study will highlight the effect of a short-term specific residential thermal spa program on the prevention of occupational burnout and work-related stress. The findings will be disseminated at several research conferences and in published articles in peer-reviewed journals. Trial Registration: ClinicalTrials.gov (NCT 03536624, 24/05/2018)