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It is widely known that glass–epoxy laminates are renowned for their high stiffness, good thermal properties, and economic qualities. For this reason, composite materials find successful applications in various industrial sectors such as aerospace, astronautics, the storage sector, and energy. The aim of this study was to investigate the mechanical and thermal properties of composite materials comprising two different types of epoxy resin and three different hardeners, both at room temperature and under cryogenic conditions. The samples were produced at IZOERG (Gliwice, Poland) using a laboratory hot-hydraulic-press technique. During cyclic loading–unloading tests, degradation up to a strain level of 0.6% was observed both at room temperature (RT) and at 77 K. For a glass-reinforced composite with YDPN resin (EP_1_1), the highest degradation was recorded at 18.84% at RT and 33.63% at 77 K. We have also investigated the temperature dependence of thermal conductivity for all samples in a wide temperature range down to 5 K. The thermal conductivity was found to be low and had a relative difference of up to 20% among the composites. The experimental results indicated that composites under cryogenic conditions exhibited less damage and were stiffer. It was confirmed that the choice of hardener significantly influenced both properties. [ABSTRACT FROM AUTHOR]

A review of defect types in the production of corundum ceramic tiles and conventional methods for testing the integrity of products made from this material has been conducted. The integrity of tiles containing artificial defects was studied using the active thermal testing method with pulsed optical heating. A two-sided thermal testing setup was employed with software processing of the initial thermograms using Parker's method. It was established that the best results for detecting internal defects in 10 mm thick ceramic tiles during thermal stimulation with xenon lamps are achieved by the two-sided thermal testing method with the construction of thermal diffusivity maps. [ABSTRACT FROM AUTHOR]

The types of defects and ways of their formation in the production of tiles from corundum ceramics are considered. The integrity of tiles containing artificial defects has been investigated by the method of active thermal nondestructive testing using optical heating. One- and two-sided thermal testing schemes as well as various methods of software processing of thermograms are applied. It has been established that the best results in detecting internal defects in ceramic tiles with a thickness of 10 mm during thermal stimulation using halogen lamps are obtained by the method of one-sided thermal testing. [ABSTRACT FROM AUTHOR]

The set of operations on diagnosing the changes in the properties of materials due to aging includes accelerated climate tests (ACTs) and pre- and post-ACT performance tests. Along with the use of various methods for diagnosing defects that arise and develop during aging, it is also important to determine changes in the thermophysical, hydrophysical, and other properties of materials subject to long-term operation that are associated with changes in the material structure. In this paper, we present a method for synchronous calculation of changes in thermophysical and hydrophysical properties of materials due to material aging and respective changes to the hygrothermal modes of products under long-term storage and operation. An experimental setup and a method for experimental-analytical determination of the thermophysical properties of materials at variable heating rates, as well as a method of synchronous calculation, are presented. The experimental-analytical determination method was developed using the results of thermal testing of specimens both subjected to ACT and without ACT. The analysis of the test results makes use of the approximation-superposition method to solve the inverse heat conduction problem. [ABSTRACT FROM AUTHOR]

The monitoring unit used in the nuclear magnetic resonance system, as an important unit of the system, faces a high thermal risk during its entire life cycle. This paper ensures the high efficiency and reliability of the thermal design of the product module from the two dimensions of structural design and device derating design. In order to reduce the risk of thermal design of electronic modules and comprehensively verify the effectiveness of thermal design of electronic modules, the design verification is carried out by combining simulation and experiment. In the simulation process, by establishing a thermal simulation model at the circuit board level, the crustal temperature of the core device is numerically calculated, and the index is compared with the thermal design index value and the test value, on the one hand, to verify the correctness of the simulation model. On the other hand, the validity of thermal design is verified. In the testing process, a thermal test platform for product modules is built, and the thermal characteristics test values of the core components of the module under extreme electrical conditions are obtained, and the corresponding conversion methods are used to predict the thermal performance and thermal design margin of the product at different altitudes. The results show that the electronic module can meet the thermal design requirements in terms of structural design and derating design of core components, and can ensure that the product module can work safely and reliably during the entire life cycle of the NMR system.

The methods of production of corundum ceramics with specified characteristics are reviewed and possible causes of hidden defects are indicated. Ceramic samples for research were obtained by the method of slip casting and their physical properties were determined. The possibility of diagnosing the integrity of corundum ceramic plates was investigated by the method of active thermal nondestructive testing. Various testing schemes and sources of thermal stimulation of the studied samples were applied. X-ray inspection was used as a reference method and confirmed the characteristics of a defect detected by the thermal method in the test sample. [ABSTRACT FROM AUTHOR]

We describe the results of using thermal imagers of six types, i.e., having different technical characteristics (with a matrix from to and sensitivity from 25 to 110 mK) in various price segments, for active thermal testing (TT) of delaminations with sizes from to mm located at a depth of 3.1 mm in a test sample of polymethylmethacrylate. The effectiveness of thermal testing was determined with the participation of nine thermograph operators. It is demonstrated that acceptable thermal testing results are possible when using thermal imagers and thermal imaging modules of the low-budget segment. [ABSTRACT FROM AUTHOR]

In recent years, thermal testing has been a rapidly developing field of nondestructive testing due to the development of composite materials, testing of which by conventional methods is difficult. Undoubted progress has been made in the development and commercialization of thermal imagers that form the basis of thermal flaw detectors. Starting from earlier reviews, the author tried to summarize the achievements of recent years both in the methodology of testing and processing of temperature information and in the development of modern thermal flaw detectors and their fields of application. The review includes domestic achievements in the field of thermal testing and numerous foreign studies, thanks to which thermal testing is considered as one of the main methods for nondestructive testing of certain classes of materials and structures. [ABSTRACT FROM AUTHOR]

PCMs are attractive for the future generation of buildings, where energy efficiency targets and thermal comfort expectations are increasingly prioritized. Experimental analysis of local thermal processes in these dynamic components and whole-building energy consumption predictions are essential for the proper implementation of PCMs in buildings. This paper discusses the experimental analysis of the thermophysical characteristics of both a latent heat storage material (PCM) and a product containing this PCM. The prototype product under investigation is a panelized PCM technology containing inorganic, salt-hydrate-based PCM. The thermal analysis includes studies of melting and freezing temperatures, enthalpy changes during phase change processes, nucleation intensity, sub-cooling effects, and PCM stability. The PCM's stability is also investigated, as is the ability of PCM products to control local temperatures and peak load transmission times. Two inorganic PCM formulations based on calcium chloride hexahydrate (CaCl2.6H2O) were prepared and tested in laboratory conditions. Material-scale testing results were compared with outcomes from the system-scale analysis, using both laboratory test methods as well as field exposure in test huts. This work demonstrates that PCM technologies used in buildings can effectively control both the magnitude of thermal storage capacity as well as the time of the peak thermal load. It was found that commonly used material-scale testing methods may not always be beneficial in assessing the dynamic thermal performance characteristics of building technologies containing PCMs. [ABSTRACT FROM AUTHOR]

Lithium-ion battery packs used in micro-mobility devices, such as e-bikes and e-scooters can lead to substantial safety hazards should a single cell go into thermal runaway. In this paper we explore the extent and severity of e-mobility battery fires resulting from a single cell thermal runaway failure and evaluate various suppression techniques a user may attempt to implement if they experience a battery fire at home. We tested a household water hose as well as different fire blankets deployed both before the forced thermal runaway event and after initiation. The water hose was unable to supply a sufficient amount of water to extinguish the thermal event, however, the average pack temperature was decreased and the cell-to-cell propagation rate was slowed. Neither fire blanket tested was able to contain the flames or debris ejected from the battery packs and both acted to hold in the heat from the event, increasing the temperature, rather than allowing it to dissipate. In addition, we also demonstrated how various design approaches, such as added thermal insulation between cells, can help prevent cell-to-cell propagation and reduce the severity of a battery pack failure.

We describe the application of active thermal testing using optical heating and ultrasonic stimulation for products manufactured by additive technologies, namely, carbon fiber composites with impact damage and delaminations, construction wall panels with air channels and metal cylinders with continuity defects. The use of the thermal method is most effective in the case of materials characterized by considerable attenuation of ultrasound that prevents the use of standard ultrasound testing. It is advisable to detect discontinuities of small sizes using ultrasonic IR thermography, since in this case local temperature signals arise only in defective zones due to the friction of defect walls, while the temperature of the base material does not change. [ABSTRACT FROM AUTHOR]

Currently, along with growth in industrial production, the requirements for product quality testing are also increasing. In the tasks of defectoscopy and defectometry of multilayer materials, the use of thermal nondestructive testing method is promising. At the same time, interpretation of thermal testing data is complicated by a number of factors, which makes the use of traditional methods of data processing ineffective. Therefore, an urgent task is to search for new methods of thermal testing that will automate the diagnostic process and increase information content of obtained results. The purpose of article is to use the advances in deep learning for processing results of active thermal testing of products made of multilayer materials and development of an automated system for thermal defectoscopy and defectometry of such products. The proposed system consists of a heating source, an infrared camera for recording sequences of thermograms and a digital information processing unit. Three neural network modules are used for automated data processing, each of which performs one of the tasks: defects detection and classification, determination of the defect depth and thickness. The software algorithms and user interface for interacting with system are programmed in the NI LabVIEW development environment.Experimental studies on samples made of multilayer fiberglass have shown a significant advantage of the developed system over using traditional methods for analyzing thermal testing data. The defect classification (determining the type) error on the test dataset was 15.7 %. Developed system ensured determination of defect depth with a relative error of 3.2 %, as well as the defect thickness with a relative error of 3.5 %.

PCMs are attractive for the future generation of buildings, where energy efficiency targets and thermal comfort expectations are increasingly prioritized. Experimental analysis of local thermal processes in these dynamic components and whole-building energy consumption predictions are essential for the proper implementation of PCMs in buildings. This paper discusses the experimental analysis of the thermophysical characteristics of both a latent heat storage material (PCM) and a product containing this PCM. The prototype product under investigation is a panelized PCM technology containing inorganic, salt-hydrate-based PCM. The thermal analysis includes studies of melting and freezing temperatures, enthalpy changes during phase change processes, nucleation intensity, sub-cooling effects, and PCM stability. The PCM’s stability is also investigated, as is the ability of PCM products to control local temperatures and peak load transmission times. Two inorganic PCM formulations based on calcium chloride hexahydrate (CaCl2.6H2O) were prepared and tested in laboratory conditions. Material-scale testing results were compared with outcomes from the system-scale analysis, using both laboratory test methods as well as field exposure in test huts. This work demonstrates that PCM technologies used in buildings can effectively control both the magnitude of thermal storage capacity as well as the time of the peak thermal load. It was found that commonly used material-scale testing methods may not always be beneficial in assessing the dynamic thermal performance characteristics of building technologies containing PCMs.

Construction is the part of human activity which is directly linked to urbanization for moving ahead on the path of growth and prosperity. Construction activities in past centuries are now part of our precious heritage. The repair and maintenance of heritage structures are of great importance for present-day researchers. One of the most common damage these century-long constructions faces are in form of surface cracks. In the present study, investigations were performed for a 3D printing-based customized solution for crack repair and maintenance of heritage structures. In this study, polyvinylidene fluoride (PVDF) polymer was reinforced with graphene (Gr) and Mn-doped ZnO nano-particles to prepare a smart composite material for crack repair and restoration. The composite was successfully 3D printed on fused deposition modeling (FDM) based 3D printer after investigating its rheological, thermal, and mechanical properties. The in-house developed composite was tested for smart characteristics to use as a programmable solution for filling cracks. The piezoelectric property and dielectric constant of 3D printed disk-shaped composite (PVDF-Gr-Mn-ZnO) were obtained after DC poling (to be used as stimulus) of the functional prototype. The results of the study suggest that the electro-active nature, volumetric change, and charge storing capacity of the additively manufactured composite may be used practically to acquire the shape of cavity/crack present in the constructed wall and repair the damages that occurred in a heritage site. The photoluminescence (PLS) and atomic force microscopy (AFM) analysis was used to ascertain the properties of the prepared composite. Also, the results obtained from the morphological analysis are reported to support the outcomes of the research. [ABSTRACT FROM AUTHOR]

Objective: Quantitative thermal testing (QTT) is a psychophysical assessment method of small nerve fibers that relies on reference material to assess function. Normal limits for within-subject comparisons of thermal thresholds are scarce, and their association with age, height and sex is not fully elucidated. The aim of this study was to investigate the normal limits for distal-proximal– and contralateral homologous comparisons of thermal thresholds with QTT, and their association with age, sex or height. Methods: Fifty healthy volunteers ages 20–79 participated in the experiment. Cold detection thresholds (CDT), warm detection thresholds (WDT), heat pain thresholds (HPT), and cold pain thresholds (CPT) were measured bilaterally at the thenar eminence, anterior thigh, distal medial leg and foot dorsum. Sample normal limits were calculated as (mean) ± 2 SD. Results: Forty-eight subjects were included in the analysis. CPT was excluded from all analyses due to a large floor-effect. Sample normal limits for side-differences ranged from 1.8 to 7.2 °C for CDT, 2.4–6.8 °C for WDT and 3.2–4.0 °C for HPT, depending on anatomical site. For distal-proximal comparisons, sample normal limits ranged from 4.0 to 8.7 °C for CDT, 6.0–14.0 °C for WDT and 4.2–9.0 °C for HPT, depending on the pairs compared. Age was associated with side-differences for CDT in the thenar eminences (p

The method of one-sided active thermal nondestructive testing based on the analysis of radiation temperatures was used to study the possibility of monitoring surface oxidation of zirconium. At various stages and temperatures of heating in the infrared wavelength range, the emissivity of the oxidized surface of zirconium samples obtained at different annealing temperatures was estimated. It is shown that there is a fundamental possibility of remotely monitoring the oxidation process of zirconium alloys used in the nuclear industry for the manufacture of fuel elements operating in the core of nuclear reactors. [ABSTRACT FROM AUTHOR]

Burning mouth syndrome (BMS) is a chronic orofacial pain condition that mainly affects postmenopausal women. BMS type I patients report little to no spontaneous pain in the morning and increases in pain through the day, peaking in the afternoon. Quantitative sensory testing (QST) findings from BMS type 1 patients are inconsistent as they fail to capture this temporal variation. We examined how QST in BMS type 1 (n = 18) compared to healthy participants (n = 33) was affected by time of day. QST of the face and forearm included warmth detection threshold (WDT), cold detection threshold (CDT), and heat pain thresholds (HPT), ratings of suprathreshold heat, and pressure pain thresholds (PPT), and was performed twice: once in the morning and once in the afternoon. Compared to healthy participants, BMS patients had higher pain sensitivity to phasic heat stimuli at most temperatures (35°C U = 126.5, p = 0.0006, 39°C U = 186.5, p = 0.0386, 41°C U = 187.5, p = 0.0412, 43°C U = 171, p = 0.0167, 45°C U = 168.5, p = 0.0146) on the forearm, but no differences in pain thresholds (HPT and PPT) regardless of time of day or body area tested. BMS patients had higher WDT (U = 123, p = 0.0172), and lower CDT (U = 98, p = 0.0021) of the forearm and lower WDT of the face (U = 55, p = 0.0494). The differences in forearm WDT (U = 71.5, p = 0.0113) and CDT (U = 70, p = 0.0096) were most pronounced in the morning. In summary, BMS type I patients had increased pain sensitivity on the forearm, but no differences in pain thresholds on the face or forearm. Patients also showed altered thermal sensitivity, which depended on body area tested (heightened in the orofacial region but blunted on the forearm), and was more pronounced in the morning plausibly due to hypervigilance. [ABSTRACT FROM AUTHOR]

Burning mouth syndrome (BMS) is a chronic orofacial pain condition that mainly affects postmenopausal women. BMS type I patients report little to no spontaneous pain in the morning and increases in pain through the day, peaking in the afternoon. Quantitative sensory testing (QST) findings from BMS type 1 patients are inconsistent as they fail to capture this temporal variation. We examined how QST in BMS type 1 (n = 18) compared to healthy participants (n = 33) was affected by time of day. QST of the face and forearm included warmth detection threshold (WDT), cold detection threshold (CDT), and heat pain thresholds (HPT), ratings of suprathreshold heat, and pressure pain thresholds (PPT), and was performed twice: once in the morning and once in the afternoon. Compared to healthy participants, BMS patients had higher pain sensitivity to phasic heat stimuli at most temperatures (35°C U = 126.5, p = 0.0006, 39°C U = 186.5, p = 0.0386, 41°C U = 187.5, p = 0.0412, 43°C U = 171, p = 0.0167, 45°C U = 168.5, p = 0.0146) on the forearm, but no differences in pain thresholds (HPT and PPT) regardless of time of day or body area tested. BMS patients had higher WDT (U = 123, p = 0.0172), and lower CDT (U = 98, p = 0.0021) of the forearm and lower WDT of the face (U = 55, p = 0.0494). The differences in forearm WDT (U = 71.5, p = 0.0113) and CDT (U = 70, p = 0.0096) were most pronounced in the morning. In summary, BMS type I patients had increased pain sensitivity on the forearm, but no differences in pain thresholds on the face or forearm. Patients also showed altered thermal sensitivity, which depended on body area tested (heightened in the orofacial region but blunted on the forearm), and was more pronounced in the morning plausibly due to hypervigilance.

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. [ABSTRACT FROM AUTHOR]

• An experiment is designed to verify the thermal characteristics of the 1D-CFC tile. • A finite element method is adopted to validate the parameters of the 1D-CFC material. An important aspect of the Comprehensive Research Facility for Fusion Technology (CRAFT) project is to conduct research on neutral beam injection based on accelerated negative ions, which is one of the main auxiliary heating methods. To evaluate beam characteristics, a diagnostic calorimeter based on a unidirectional carbon fiber-carbon matrix (CFC) composite has been developed in the negative ion source test facility. The CFC calorimeter can diagnose key features of a particle beam, including its divergence and uniformity. The CFC calorimeter has been developed by a worldwide research team of neutral beam injection (NBI) due to its high spatial resolution, which is determined by the thermal properties of CFC materials. This paper aims to verify the thermal properties of CFC materials from TianCe Technology Co., Ltd. by comparing data acquired by infrared (IR) camera with simulations. Experimental and simulation results show that the CFC material provided by the company satisfies the requirements of experiment. [ABSTRACT FROM AUTHOR]

NASA is the mission lead for the James Webb Space Telescope (JWST), the next of the "Great Observatories," scheduled for launch in 2021. NASA is directly responsible for the integration and test (I&T) program that culminated in an end-to-end cryo vacuum optical test of the flight telescope and instrument module in Chamber A at NASA Johnson Space Center. Historic Chamber A is the largest thermal vacuum chamber at Johnson Space Center and one of the largest space simulation chambers in the world. Chamber A has undergone a major modernization effort to support the deep cryogenic, vacuum and cleanliness requirements for testing the JWST. This paper describes the upgrades to the Chamber A facility: Thermal Shrouds, Helium Refrigeration, Liquid Nitrogen System, High Vacuum System, Clean Airflow System, and Utilities. [ABSTRACT FROM AUTHOR]

Flaw detection of tubular refractory products was carried out by the method of thermal testing. It is shown that the method of two-way active thermal testing is applicable for detecting production defects of ceramic rollers. Defects such as cracks and holes, as well as some surface inhomogeneities were found in the studied samples. [ABSTRACT FROM AUTHOR]

Thanks to its good strength/mass ratio, a glass fibre reinforced plastic (GFRP) composite is a common material widely used in aviation, power production, automotive and other industries. In its turn, active infrared (IR) nondestructive testing (NDT) is a common inspection technique for detecting and characterizing structural defects in GFRP. Materials to be tested are typically subjected to optical heating which is supposed to occur on the material surface. However, GFRP composite is semi-transparent for optical radiation of both visual and IR spectral bands. Correspondingly, the inspection process represents a certain combination of both optical and thermal phenomena. Therefore, the known characterization algorithms based on pure heat diffusion cannot be applied to semi-transparent materials. In this study, the phenomenon of GFRP semi-transparency has been investigated numerically and experimentally in application to thermal NDT. Both Xenon flash tubes and a laser have been used for thermal stimulation of opaque and semi-transparent test objects. It has been shown that the penetration of optical heating radiation into composite reduces detectability of shallower defects, and the signal-to-noise ratio can be enhanced by applying the technique of thermographic signal reconstruction (TSR). In the inspection of the semi-transparent GFRP composite, the most efficient has been the laser heating followed by the TSR data processing. The perspectives of defect characterization of semi-transparent materials by using laser heating are discussed. A neural network has been used as a candidate tool for evaluating defect depth in composite materials, but its training should be performed in identical with testing conditions. [ABSTRACT FROM AUTHOR]

A complex technique for thermal characterization of small-sized defects such as discontinuities in intricately shaped composite structures is presented. The complex defect characterization technique is based on revealing and identifying internal defects as sources of heat due to extraneous stimulation sources. The use of this complex technique makes it possible to identify types of defects that remain virtually unnoticed with the existing methods, for example, defects of small sizes, closed cracks, microcracks, etc. and determine their location in the material. It is shown that the error in determining the depth of defects in the material by the proposed integrated technique is better than 10–15%, a figure that is quite acceptable for practical usage. [ABSTRACT FROM AUTHOR]