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Статті в журналах з теми "Temperature measurement through infrared thermography":
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Calvo-Lobo, Cesar, Marta San-Antolín, Daniel García-García, Ricardo Becerro-de-Bengoa-Vallejo, Marta Elena Losa-Iglesias, Julia Cosín-Matamoros, Israel Casado-Hernández, Eva María Martínez-Jiménez, Victoria Mazoteras-Pardo, and David Rodríguez-Sanz. "Intra- and inter-session reliability and repeatability of an infrared thermography device designed for materials to measure skin temperature of the triceps surae muscle tissue of athletes." PeerJ 11 (March 9, 2023): e15011. http://dx.doi.org/10.7717/peerj.15011.
Анотація:
Background Infrared thermography devices have been commonly applied to measure superficial temperature in structural composites and walls. These tools were cheaper than other thermographic devices used to measure superficial human muscle tissue temperature. In addition, infrared thermography has been previously used to assess skin temperature related to muscle tissue conditions in the triceps surae of athletes. Nevertheless, the reliability and repeatability of an infrared thermography device designed for materials, such as the Manual Infrared Camera PCE-TC 30, have yet to be determined to measure skin temperature of the triceps surae muscle tissue of athletes. Objective The purpose was to determine the procedure’s intra- and inter-session reliability and repeatability to determine skin temperature within the Manual Infrared Camera PCE-TC 30 thermography device in the triceps surae muscle tissue of athletes, which was initially designed to measure the superficial temperature of materials. Methods A total of 34 triceps surae muscles were bilaterally assessed from 17 healthy athletes using the Manual Infrared Camera PCE-TC 30 thermography device to determine intra- (at the same day separated by 1 h) and inter-session (at alternate days separated by 48 h) reliability and repeatability of the skin temperature of the soleus, medial and lateral gastrocnemius muscles. The triceps surae complex weas measured by a region of interest of 1 cm2 through five infrared thermography images for each muscle. Statistical analyses comprised intraclass correlation coefficient (ICC), standard error of measurement (SEM), minimum detectable change (MCD), systematic error of measurement, correlation (r), and Bland-Altman plots completed with linear regression models (R2). Results Intra- and inter-session measurements of the proposed infrared thermography procedure showed excellent reliability (ICC(1,2) = 0.968–0.977), measurement errors (SEM = 0.186–0.232 °C; MDC = 0.515–0.643 °C), correlations (r = 0.885–0.953), and did not present significant systematic error of measurements (P > 0.05). Adequate agreement between each pair of measurement moments was presented by the Bland-Altman plots according to the limits of agreement and non-significant linear regression models (R2 = 0.000–0.019; P > 0.05). Conclusions The proposed procedure to determine skin temperature within the Manual Infrared Camera PCE-TC 30 thermography device presented excellent intra- and inter-session reliability and repeatability in athletes’ triceps surae muscle tissue. Future studies should consider the SEM and MDC of this procedure to measure the skin temperature of soleus, medial, and lateral gastrocnemius muscles to promote triceps surae muscle prevention and recovery in athletes.
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Ushiki, Tomohiko, Ryota Imazawa, Hidetoshi Murakami, Kosuke Shimizu, Tatsuo Sugie, and Takaki Hatae. "Dual two-color method: A new concept of ultra-wide temperature range thermography (200–3600 °C) for ITER divertor infrared thermography." Review of Scientific Instruments 93, no. 8 (August 1, 2022): 084905. http://dx.doi.org/10.1063/5.0089269.
Анотація:
A new temperature measurement method—the dual two-color method—was developed to accurately measure the temperature over an ultra-wide temperature range (200–3600 °C) for ITER divertor infrared thermography. This novel method introduces a third wavelength filter to the conventional two-color method by replacing the shorter single wavelength bandpass filter with a customized dual-bandpass filter having two transmission bands, without having to add a third infrared camera. The dominant wavelength band of the total radiance through the dual-band filter changes automatically as the temperature increases and, consequently, either the shorter or longer wavelength band of the dual-bandpass filter is used to establish the two-color combination at both low and high temperatures. The dual two-color method increased the acceptable measurement error of the two-color radiance ratio for the temperature measurement requirement of the ITER divertor infrared thermography to 9.45% from that of 4.3% when using the conventional two-color method.
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Kolosovas-Machuca, Eleazar S., Mario A. Martínez-Jiménez, José L. Ramírez-GarcíaLuna, Francisco J. González, Amaury J. Pozos-Guillen, Nadia P. Campos-Lara, and Mauricio Pierdant-Perez. "Pain Measurement through Temperature Changes in Children Undergoing Dental Extractions." Pain Research and Management 2016 (2016): 1–5. http://dx.doi.org/10.1155/2016/4372617.
Анотація:
Background and Objective.Pain evaluation in children can be a difficult task, since it possesses sensory and affective components that are often hard to discriminate. Infrared thermography has previously been used as a diagnostic tool for pain detection in animals; therefore, the aim of this study was to assess the presence of temperature changes during dental extractions and to evaluate its correlation with heart rate changes as markers of pain and discomfort.Methods. Thermographic changes in the lacrimal caruncle and heart rate measurements were recorded in healthy children scheduled for dental extraction before and during the procedure and compared. Afterwards, correlation between temperature and heart rate was assessed.Results. We found significant differences in temperature and heart rate before the procedure and during the dental extraction (mean difference 4.07°C,p<0.001, and 18.11 beats per minute,p<0.001) and no evidence of correlation between both measurements.Conclusion. Thermographic changes in the lacrimal caruncle can be detected in patients who undergo dental extractions. These changes appear to be stable throughout time and to possess very little intersubject variation, thus making them a candidate for a surrogate marker of pain and discomfort. Future studies should be performed to confirm this claim.
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López-Fernández, L., S. Lagüela, D. González-Aguilera, and H. Lorenzo. "Thermographic and mobile indoor mapping for the computation of energy losses in buildings." Indoor and Built Environment 26, no. 6 (March 15, 2016): 771–84. http://dx.doi.org/10.1177/1420326x16638912.
Анотація:
A mobile indoor mapping system combined with infrared thermography was used for the acquisition of data needed for the quantification of heat loss through a building envelope by conduction; that is, temperature values and building geometry. The methodology presented orthothermograms to provide measurement of heat loss and thermographic images with geometric information. This way, not only the energy loss through the building envelope is provided, but also thermographic information regarding the existence of thermal pathologies, their location and their impact on the building can also be evaluated.
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Kim, Jeong Guk, Seung Koo Baek, Chang Young Lee, and Sung Cheol Yoon. "Deterioration and Thermographic Analyses of Electrical Units in Diesel Locomotive." Key Engineering Materials 417-418 (October 2009): 729–32. http://dx.doi.org/10.4028/www.scientific.net/kem.417-418.729.
Анотація:
The electrical units of diesel electric locomotives, which were used for over 30 years, were characterized for deterioration evaluation through insulation resistance measurement, degradation testing, and infrared thermography method. Especially, an infrared camera and thermocouples were employed for the evaluation. The thermocouples were attached on high-voltage cables connected to traction motors, for in-situ measurement of abnormal heating during test running. After test running, the thermographic images were obtained for the inspection of high-voltage cables using the infrared camera. The thermographic results were quantitatively analyzed, and compared with temperature changes during running. In this investigation, various analysis techniques for the safety characterization of diesel electric locomotives have been introduced, and the analysis results have been used to provide the deterioration or wear information in current locomotive systems.
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Ren, Chao, Libing Bai, Ruilong Shi, Jie Zhang, Xu Zhang, and Cong Chen. "Measurement of current distribution using infrared thermography." Review of Scientific Instruments 94, no. 3 (March 1, 2023): 034713. http://dx.doi.org/10.1063/5.0137203.
Анотація:
Current distribution measurement methods are widely used in medical examinations, predicting faults in semiconductor devices and assessing structural integrity. Several methods for measuring current distribution are available, such as electrode arrays, coils, and magnetic sensors. However, these measurement methods are unable to obtain images of current distribution with high spatial resolution. Therefore, there is a need to develop a non-contact method to measure current distribution that is capable of capturing images with high spatial resolution. In this study, a non-contact current distribution measurement method based on infrared thermography is proposed. The method uses thermal variations to quantify the current amplitude and reconstructs the current direction based on the passivity of the electric field. For quantification of low frequency current amplitude, the experimental results show that the method can provide accurate current measurement results, for example, at the power frequency (50 Hz), in the range of 1.05–3.45 A, its relative error can be improved to ±3.66% when the calibration fitting method is used. For the high-frequency current, an effective estimate of the current amplitude is obtained using the first-order derivative of temperature variation. When applied to the eddy current detection (256 KHz), it achieves a high-resolution image of the current distribution, and the effectiveness of the method is verified through simulation experiments. The experimental results show that the proposed method not only measures the current amplitude accurately but also improves the spatial resolution in acquiring two-dimensional current distribution images.
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Kim, Won Tae, Man Yong Choi, and Jung Hak Park. "NDT Analysis of Metal Materials with Internal Defects Using Active Infrared Thermography Method." Key Engineering Materials 321-323 (October 2006): 835–40. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.835.
Анотація:
This study is aimed to analyze the thermal imaging patterns presented by infrared(IR) thermography at which the metal with internal defects are thermally heated. Through the knowledge of non-destructive testing which infrared thermography can be applied to detect the defects inside the materials, there are two materials experimented; one is stainless steel and the other is cast-iron. Thermally, each material of specimens is heated at the base of the material and kept with constant temperature, The artificial defects in the specimen are formulated. Under the shape and location of the defects, temperature profiles are also measured and validated using the computer simulation. It is concluded that the characteristics of thermal patterns obtained from IR thermography are consistent with those of measurement and computations.
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Harrap, Michael J. M., Natalie Hempel de Ibarra, Heather M. Whitney, and Sean A. Rands. "Reporting of thermography parameters in biology: a systematic review of thermal imaging literature." Royal Society Open Science 5, no. 12 (December 2018): 181281. http://dx.doi.org/10.1098/rsos.181281.
Анотація:
Infrared (IR) thermography, where temperature measurements are made with IR cameras, has proven to be a very useful and widely used tool in biological science. Several thermography parameters are critical to the proper operation of thermal cameras and the accuracy of measurements, and these must usually be provided to the camera. Failure to account for these parameters may lead to less accurate measurements. Furthermore, the failure to provide information of parameter choices in reports may compromise appraisal of accuracy and replicate studies. In this review, we investigate how well biologists report thermography parameters. This is done through a systematic review of biological thermography literature that included articles published between years 2007 and 2017. We found that in primary biological thermography papers, which make some kind of quantitative temperature measurement, 48% fail to report values used for emissivity (an object's capacity to emit thermal radiation relative to a black body radiator), which is the minimum level of reporting that should take place. This finding highlights the need for life scientists to take into account and report key parameter information when carrying out thermography, in the future.
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Wang, Xiaoshuai, Feiyue Hu, Ruimin Yang, and Kaiying Wang. "An Infrared Temperature Correction Method for the Skin Temperature of Pigs in Infrared Images." Agriculture 13, no. 3 (February 21, 2023): 520. http://dx.doi.org/10.3390/agriculture13030520.
Анотація:
Accurately measuring the skin temperature of pigs is essential to large-scale pig farming for health monitoring, as well as disease detection and prevention. Infrared thermography (IRT) is a promising technology for the non-invasive measuring of pig skin temperature. However, the distance and angle of view of measurement greatly affect the accuracy of IRT-measured temperature. To improve the accuracy of the measurement, this study starts with evaluating the effects of four parameters on the measurement of skin temperature: horizontal distance, camera height, pig height, and angle of view between the object and the IRT camera. It follows by proposing a mathematical model describing the relationship between the real skin temperature and the four parameters through means of response surface methodology. A correction algorithm is then developed based on the mathematical model to improve the measuring accuracy. In order to evaluate the performance of the correction algorithm, the measured skin temperatures before and after correction are compared with the actual ones. The comparison was carried out in an experimental pig farm with 25 randomly selected pigs. The results show that the mean relative error before the correction was −4.64% and the mean relative error after the correction was −0.70%. This study demonstrates that the new infrared temperature correction method is effective and can benefit skin temperature monitoring for commercial pig farms.
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Mineo, Simone, and Giovanna Pappalardo. "Rock Emissivity Measurement for Infrared Thermography Engineering Geological Applications." Applied Sciences 11, no. 9 (April 22, 2021): 3773. http://dx.doi.org/10.3390/app11093773.
Анотація:
Infrared thermography is a growing technology in the engineering geological field both for the remote survey of rock masses and as a laboratory tool for the non-destructive characterization of intact rock. In this latter case, its utility can be found either from a qualitative point of view, highlighting thermal contrasts on the rock surface, or from a quantitative point of view, involving the study of the surface temperature variations. Since the surface temperature of an object is proportional to its emissivity, the knowledge of this last value is crucial for the correct calibration of the instrument and for the achievement of reliable thermal outcomes. Although rock emissivity can be measured according to specific procedures, there is not always the time or possibility to carry out such measurements. Therefore, referring to reliable literature values is useful. In this frame, this paper aims at providing reference emissivity values belonging to 15 rock types among sedimentary, igneous and metamorphic categories, which underwent laboratory emissivity estimation by employing a high-sensitivity thermal camera. The results show that rocks can be defined as “emitters”, with emissivity generally ranging from 0.89 to 0.99. Such variability arises from both their intrinsic properties, such as the presence of pores and the different thermal behavior of minerals, and the surface conditions, such as polishing treatments for ornamental stones. The resulting emissivity values are reported and commented on herein for each different studied lithology, thus providing not only a reference dataset for practical use, but also laying the foundation for further scientific studies, also aimed at widening the rock aspects to investigate through IRT.
Дисертації з теми "Temperature measurement through infrared thermography":
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Toullier, Thibaud. "Simultaneous characterization of objects temperature and radiative properties through multispectral infrared thermography." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S038/document.
Анотація:
L'utilisation de caméras infrarouges bas coûts pour la surveillance long-terme d'infrastructures est prometteuse grâce aux dernières avancées technologiques du domaine. Une mesure précise de la température des surfaces observées in-situ se heurte au manque de connaissance des propriétés radiatives de la scène. L'utilisation d'une instrumentation multi-capteurs permet d'affiner le modèle de mesure afin d'obtenir une estimation plus précise de la température. A contrario, il est montré qu'il est toujours possible d'exploiter des données climatiques en ligne pour pallier un manque de capteur. Des méthodes bayésiennes d'estimation conjointe d'émissivité et de température sont ensuite développées et comparées aux méthodes de la littérature. Un simulateur d'échanges radiatifs diffus de scènes 3D a été implémenté afin de tester ces différentes méthodes. Ce logiciel utilise l'accélération matérielle de la machine pour réduire les temps de calcul. Les résultats numériques obtenus mettent en perspective une utilisation avancée de la thermographie infrarouge multi-spectrale pour la surveillance de structures. Cette estimation conjointe permet alors d'obtenir un estimé de la température par thermographie infrarouge avec une incertitude connueThe latest technological improvements in low-cost infrared cameras have brought new opportunities for long-term infrastructures monitoring. The accurate measurement of surfaces' temperatures is facing the lack of knowledge of radiatives properties of the scene. By using multi-sensors instrumentation, the measurement model can be refined to get a better estimate of the temperature. To overcome a lack of sensors instrumentation, it is shown that online and free available climatic data can be used. Then, Bayesian methods to estimate simultaneously the emissivity and temperature have been developed and compared to literature's methods. A radiative exchange simulator of 3D scenes have been developed to compare those different methods on numerical data. This software uses the hardware acceleration as well as a GPGPU approach to reduce the computation time. As a consequence, obtained numerical results emphasized an advanced use of multi-spectral infrared thermography for the monitoring of structures. This simultaneous estimation enables to have an estimate of the temperature by infrared thermography with a known uncertainty
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Surabhi, Vijaykumar. "Automatic Features Identification with Infrared Thermography in Fever Screening." Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/20558.
Анотація:
The goal of this thesis is to develop an algorithm to process infrared images and achieve automatic identification of moving subjects with fever. The identification is based on two main features: the distinction between the geometry of a human face and other objects in the field of view of the camera, and the temperature of the radiating object. Infrared thermography is a remote sensing technique used to measure temperatures based on emitted infrared radiation. Applications include fever screening in major public places such as airports and hospitals. Current accepted practice of screening requires people to stay in a line and temperature measurements are carried out for one person at a time. However in the case of mass screening of moving people the accuracy of the measurements is still under investigation. An algorithm constituting of image processing to threshold objects based on the temperature, template matching and hypothesis testing is proposed to achieve automatic identification of fever subjects. The algorithm was first tested on training data to obtain a threshold value (used to discriminate between face and non face shapes) corresponding to a false detection rate of 5%, which in turn corresponds to 85% probability of detection using Neyman-Pearson criterion. By testing the algorithm on several simulated and experimental images (which reflect relevant scenarios characterizing crowded places) it is observed that it can be beneficially implemented to introduce automation in the process of detecting moving subjects with fever.
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Bach, Aaron James Edward. "Interchangeability of infrared and conductive devices for the measurement of human skin temperature." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/73089/1/Aaron_Bach_Thesis.pdf.
Анотація:
This thesis is a comparative investigation of the methodology applied to human skin temperature measurement. The findings of this thesis suggest that clinical and significant differences exist between conductive and infrared devices which are commonly employed in the assessment of human skin temperature. These significant differences could potentially influence the interpretation of results, diagnosis and therefore treatment outcomes for health, clinical and exercise science applications.
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Konieczny, Mark J. "Full-Field Strain and Temperature Measurement of Epoxy Resin PR-520 Subjected to Tensile, Compressive, and Torsional Loading at Various Strain Rates." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1556880386878411.
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Grosjean, Alex. "Impact of geometry and shaping of the plasma facing components on hot spot generation in tokamak devices." Electronic Thesis or Diss., Aix-Marseille, 2020. http://www.theses.fr/2020AIXM0556.
Анотація:
Cette thèse s’inscrit en support du projet ITER, sur l’étude du comportement thermique de prototypes de CFP dans des tokamaks supraconducteurs : EAST et WEST. Ces prototypes correspondent à un enchaînement de monoblocs de tungstène le long d’un tube de refroidissement, séparés par des interstices (0.5 mm), qui permet d’extraire la chaleur de ces composants. L’introduction de ces interstices entre monoblocs (toroïdaux) ou entre barres de monoblocs (poloïdaux), implique que le bord poloïdal peut être exposé aux lignes de champ avec une incidence quasi-normale. Un échauffement local très important est attendu sur une fine bande latérale de la surface supérieure de chaque monobloc, qui peut être accentué dans le cas où les composants sont désalignés. Nous proposons dans ce travail d’étudier l’impact de deux géométries (arête vive et chanfrein) de ces composants ainsi que de leurs désalignements sur la génération de points chauds locaux, à l’aide de diagnostics embarqués (TC/FBG), et d’une caméra infrarouge très haute résolution (~0.1 mm/pixel), dont l’émissivité varie en fonction de la longueur d’onde, de la température, et de l’état de surface, qui évolue au contact du plasma, lors des différentes campagnes expérimentales. Les sondes de Langmuir permettront de mesurer la température du plasma, et par conséquent d’estimer les rayons de Larmor des ions, qui pourront jouer un rôle important dans la distribution locale du flux de chaleur autour des bords poloïdaux et toroïdaux. Les travaux menés ici, montrent la cohérence entre les calculs prédictifs et les résultats expérimentaux et appuient la décision d'ITER de biseauter les MBs pour protéger leurs bords d'attaqueThis PhD falls within ITER project support, aiming to study the thermal behavior of ITER-like PFC prototypes in two superconducting tokamaks: EAST (Hefei) and WEST (Cadarache). These prototypes correspond to castellated tungsten monoblocks placed along a cooling tube with small gaps (0.5 mm) between them, called plasma-facing units, to extract the heat from the components. The introduction of gaps between monoblocks (toroidal) and plasma-facing units (poloidal), to relieve the thermomechanical stresses in the divertor, implies that poloidal leading edges may be exposed to near-normal incidence angle. A local overheating is expected in a thin lateral band at the top of each monoblocks, which can be enhanced when the neighboring components are misaligned. In this work, we propose to study the impact of two geometries (sharp and chamfered LEs) of these components, as well as their misalignments on local hot spot generation, by means of embedded diagnostics (TC/FBG), and a submillimeter infrared system (~0.1 mm/pixel), whose emissivity varies with wavelength, and the temperature, but above all, the surface state of the component, which evolves under plasma exposure, during the experimental campaigns. The divertor Langmuir probes measure the plasma temperature, and thus estimate the ion Larmor radius that may play a role in the local heat flux distribution around poloidal and toroidal edges. The results presented in this thesis, confirming the modelling predictions by experimental measurements, support the final decision by ITER to include 0.5 mm toroidal beveling of monoblocks on the vertical divertor targets to protect poloidal leading edges from excessive heat flux
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Constantinou, Marios, Michael Gehde, René Fuhrich, Eduard Schüle, and Christian Mittler. "Entwicklung einer Temperaturmessmethodik für die aktive Strahlerleistungs- und Strahlerabstandsregelung beim Infrarotschweißen von Kunststoffen." Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-231137.
Анотація:
Aufgrund der komplexen Strahler-Werkstoff-Wechselwirkung beim Erwärmen von Kunststoffen mit Infrarotstrahlung ist in vielen Infrarotschweißprozessen eine Rauchentwicklung zu beobachten. Diese tritt oftmals bei ruß- und/oder glasfasergefüllten Kunststoffen auf und resultiert in einem thermisch-oxidativen Werkstoffabbau, welcher zu einer Abnahme der mechanischen und thermischen Verbindungseigenschaften führt. Die Rauchbildung kann zudem lufttechnische Maßnahmen, wie Absaugeinrichtungen, an der Schweißmaschine erforderlich machen.
Der Problematik der Rauchentwicklung beim Infrarotschweißen (IR-Schweißen) von Kunststoffen wird derzeit mit zeitintensiven, empirischen Voruntersuchungen zur Parameterfindung entgegengewirkt. Ziel ist es Strahlerabstands-Erwärmzeit-Kombinationen zu finden, die zu einer ausreichenden Schmelzeerzeugung bei möglichst niedriger thermisch-oxidativer Werkstoffbelastung führen. Ein Ansatz zur Reduzierung des Vorversuchsaufwandes ist die Temperaturmessung der bestrahlten Substratoberfläche, welche unterhalb der Zersetzungstemperatur des bestrahlten Kunststoffs liegen sollte. Derzeitig können jedoch nur ergänzende thermographische und pyrometrische Temperaturmesssysteme eingesetzt werden, welche eine vergleichende Messung der Prozesstemperaturen beim IR-Schweißen ermöglichen und die Prozessstabilität des IR-Schweißprozesses in einem festgelegten Prozessfenster gewährleisten. Eine Messung der tatsächlichen Kunststofftemperaturen ist mit diesen Systemen nicht möglich. Aktuell hat eine Änderung der zu schweißenden Kunststoffe, der Füllstoffe (z. B. Glasfasern) oder ein Schwanken der Füll-und Verstärkungsstoffgehalte der Kunststoffe zur Folge, dass neue Voruntersuchungen zur Prozessparameterfindung des IR-Schweißprozesses notwendig werden.
Aufgrund dessen entwickeln die Professur Kunststoffe an der Technischen Universität Chemnitz und die Firma Eugen Riexinger aus Bad Liebenzell eine Temperaturmessmethodik zur Bestimmung der tatsächlich auftretenden Substrattemperaturen während der Infraroterwärmung von Kunststoffen. Die Methodik soll eine IR-Erwärmung von Kunststoffen auf eine kunststoffabhängige Soll-Temperatur ermöglichen und verhindert so die Rauchbildung während der IR-Erwärmung und damit die thermisch-oxidative Werkstoffschädigung.
Der Beitrag beschreibt die aktuell auftretenden Herausforderungen beim IR-Schweißen von Kunststoffen, die gewählte Herangehensweise an die Entwicklung der Temperaturmessmethodik zur Bestimmung der tatsächlichen Substrattemperatur sowie die Ergebnisse des Entwicklungsprozesses.
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Lacourarie, Fiona. "Caractérisation thermique et lumineuse de diodes électroluminescentes en charge par méthodes locales non intrusives : influence du luminophore." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2015. http://www.theses.fr/2015EMAC0003/document.
Анотація:
Le marché des diodes électroluminescentes (LEDs) de puissance est en perpétuelle croissance depuis une vingtaine d’années. Le marché de l’éclairage évolue car les besoins ont changé : nous souhaitons, par exemple, aujourd’hui réduire la consommation électrique, ou avoir des éclairages plus flexibles (couleur, cycle d’allumage, encombrement, …). Les LEDs de puissance permettent d’apporter des solutions où les autres éclairages font défauts. Une étude comparative est menée entre les LEDs et les autres sources d’éclairages. Une LED de puissance émettant une lumière blanche est constituée d’une puce semi-conductrice, d’un substrat, d’un PAD et d’une optique primaire. Différentes méthodes permettent d’obtenir de la lumière blanche avec des LEDs : plusieurs puces, une puce avec un ou des luminophores, ou la méthode PRS-LED. Le luminophore a un rôle optique important et un rôle thermique non négligeable. Après avoir été excité par la lumière émise de la puce, il réémet de la lumière dans une longueur d’onde supérieure. L’efficacité de ce processus dépend de nombreux paramètres, comme la mise en oeuvre du luminophore ou le type de luminophore utilisé. L’étude et la caractérisation des propriétés optiques et thermiques sont faites pour des LEDs commerciales, composées d’une même puce émettant de la lumière bleue, avec et sans luminophore jaune. Afin de maitriser le maximum de facteurs, nous avons mené une étude et un dimensionnement du circuit imprimé (PCB) sur lequel va être implanté nos LEDs. Dans le but d’évaluer les matériaux constituant les LEDs, des analyses au microscope à balayage électronique et par microsonde ont été menées. Ces travaux ont permis de révéler, notamment, la position de la jonction p-n dans la puce et la composition de la couche de luminophore par deux types différents. De plus, afin d’améliorer notre compréhension, une étude comparative a été menée sur trois luminophores jaunes. Ensuite, les deux types de LEDs, puce nue et puce avec luminophore, ont été testés dans le but d’obtenir le flux lumineux et le rendement des LEDs. La caractérisation optique nous a amené à créer un banc pour obtenir la luminance énergétique spectrale sur une partie minime de la puce. D’autre part, nous nous intéressons à la température de jonction de la puce nue, que nous mesurons par différentes méthodes, dont la thermographie infrarouge. Pour cela, l’émissivité a été estimée pour la puce nue et la puce avec luminophore. Puis nous comparons aussi ces différentes méthodes pour le calcul de la résistance thermique Rth j-PAD entre la jonction et le PAD. Le maillage de fils conducteurs implanté sur la surface de la puce est modélisé électriquement. Cette étude, qui est composée de niveaux progressifs de modélisation, permet de comprendre la répartition du courant électrique qui traverse la jonction, et ainsi d’appréhender la répartition du flux lumineux et de la température au niveau de la surface de la puce. Après, un modèle thermo-optique décrit les phénomènes présents au niveau de la jonction d’une puce nue : la conversion de la puissance électrique en lumière bleue et en chaleur, et les transferts de chaleur. Nous complétons ce premier modèle pour obtenir un modèle d’une puce avec le luminophore. Ce dernier modèle prend en compte la photo-conversion du luminophore avec le calcul de flux lumineux à la sortie du luminophore et le calcul de la chaleur due à la photo-conversion. La résolution de ce modèle nous permet d’obtenir la température de jonction d’une puce avec luminophore. La conservation d’énergie du modèle est aussi vérifiée. Le modèle thermo-optique est appliqué à une cartographie de température de surface afin d’obtenir une cartographie de la température de jonction. Ces cartographies sont regroupées avec les clichés de thermographie infrarouge et de luminance énergétiqueThe high brightness LED market is constantly growing last twenty years. The lighting market is changing as needs have changed: we would like, for example, reduce power consumption, or have more flexible lighting (color, lighting cycle, dimensions ...). High brightness LEDs help provide solutions where others are lighting defects. A comparative study is conducted between the LEDs and other lighting sources.The operation of a high brightness LED emitting white light is explained with the description of each element: chip, substrate, the PAD and optics. Then the different methods of obtaining white light with LEDs are compared: several chips, a chip with one or more phosphors, or PRS-LED method. The phosphor has a significant optical role and an important thermal role. After being excited by the light emitted from the chip, it re-emits light in a greater wavelength. The effectiveness of this process depends on many parameters, such as the implementation of the phosphor, or the type of phosphor used. The study and characterization of optical and thermal properties are made for commercial LEDs, composed of a single chip emitting blue light with and without yellow phosphor. To master the maximum factors, we conducted a study and design of the printed circuit board (PCB) on which will be implanted our LEDs. In order to evaluate the materials constituting the LEDs, analyzes made at scanning electron microscope, and by microprobe were conducted. This work has revealed in particular the position of the p-n junction in the chip, and the composition of the phosphor layer of two different types. Moreover, to improve our understanding, a comparative study will be conducted on three yellow phosphors. Then the two types of LEDs, bare chip and chip with phosphor, were tested in order to obtain the luminous flux and efficiency of LEDs. The optical characterization has led us to create a bench for spectral radiance over a small portion of the chip. Furthermore, we are interested in the junction temperature of the bare chip, which we measure by various methods, including infrared thermography. For this, the emissivity was estimated for the bare chip and the chip with phosphor. Then we also compare these different methods to calculate the thermal resistance Rth j-PAD between the junction and the PAD. The mesh of conductive wires, implanted on the surface of the chip, is electrically modeled. The study, which is composed of three progressive levels of modeling, provides an understanding of distribution of the electric current through the junction, and thus to understand the distribution of the light flow and temperature at the surface of the chip. Afterwards, an optical-thermal model describes the phenomena present at the junction of a bare chip: converting electrical power into blue light and heat, and heat transfer. We complete this first model for a model of a chip with the phosphor. This model takes into account the photo-conversion of the phosphor with the calculation of the luminous flux at the output of the phosphor and the calculation of the heat due to the photo-conversion. The resolution of this model allows us to obtain the junction temperature of a chip with phosphor. The model of energy conservation is also verified. The optical-thermal model is applied to a surface temperature mapping in order to obtain a mapping of the junction temperature. These maps are combined with pictures of infrared thermography and radiance
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Landfried, Romaric. "Contribution à l'étude de la transition décharge luminescente / arc électrique dans l'air et dans l'argon au voisinage de la pression atmosphérique." Phd thesis, Supélec, 2011. http://tel.archives-ouvertes.fr/tel-00789385.
Анотація:
Dans ce travail, nous proposons une approche essentiellement expérimentale. Dans une première partie, nous exposons les résultats obtenus par imagerie rapide et mesures électriques corrélées dans le temps, concernant l'étude de la transition entre des électrodes de cuivre dans l'air et l'argon, et entre des électrodes de tungstène dans l'argon pour des pressions comprises entre 100 mbar et 1 bar. Dans aucun cas une transition à l'arc n'est observée sans constriction quasi-totale de la colonne positive. Dans le cas d'électrodes en tungstène dans l'argon, la vitesse d'extension de la zone filamentaire depuis l'anode vers la cathode a été vue dépendante de la pression et de l'intensité. La durée d'une transition spontanée a été linéairement corrélée à la distance inter-électrode, suggérant un mécanisme propagatif à vitesse constante dans la colonne. Plus la pression est élevée, plus la durée totale des transitions est longue ; par ailleurs, à pression constante, cette durée de transition spontanée décroît à intensité croissante, pour tendre vers une durée limite, correspondant à la durée constante de changement de structure de la zone cathodique. Dans une seconde partie, nous nous intéressons à l'échauffement de surfaces d'anodes et de cathodes en cuivre dans l'air et dans l'argon soumises à des arcs électrique pour plusieurs gammes de courant (de 30 à 120 A). Deux méthodes de mesures sont utilisées. Enfin, nous utilisons les mesures de températures de surface pour proposer deux modèles simples de bilan de puissance à la surface des électrodes (flux de chaleur). L'un considère uniquement le chauffage dû au spot d'arc et l'autre le chauffage supplémentaire de la colonne d'arc.
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Stewart, Mairi. "Non-invasive measurement of stress and pain in cattle using infrared thermography : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Palmerston North, New Zealand." 2008. http://hdl.handle.net/10179/750.
Анотація:
The aim of this thesis was to validate the use of infrared thermography (IRT) to non-invasively measure stress and/or pain in cattle. The main approach was to measure changes in heat emitted from superficial capillaries around the eye (referred to as eye temperature) in response to various aversive husbandry procedures used routinely on farms. In addition, various exogenous challenges were given to investigate the role of the hypothalamic-pituitary-adrenal (HPA) axis and the autonomic nervous system (ANS) in regulating the eye temperature response. No evidence was found to support the hypothesis that an increase in eye temperature was due to HPA activity in cattle. A rapid drop in eye temperature occurred immediately after disbudding, an electric prod, startling and shouting. It is suggested that this was caused by the redirection of blood from the capillary beds via sympathetically-mediated vasoconstriction. Therefore, the role of the ANS was tested by measuring eye temperature, heart rate variability (HRV) and plasma catecholamine responses simultaneously. Somatic pain from disbudding and initial responses to surgical castration included a synchronised drop in eye temperature, increases in catecholamines and changes in HRV indicative of increased sympathetic activity. The role of the sympathetic nervous system was further confirmed by a drop in eye temperature that occurred following an epinephrine challenge. In contrast, deeper visceral pain from castration caused a more marked increase in eye temperature and changes in HRV indicative of increased parasympathetic tone. The underlying mechanism driving the increase in eye temperature is unknown; however, it is possible that it may be caused by vasodilation due to increased parasympathetic activity. These differences in ANS responses to different procedures, detected by IRT and HRV, may be due to the nature of the pain and the relative fear associated with the procedure. In summary, this research showed that during stress or pain, the heat emitted from superficial capillaries around the eye changes as blood flow is regulated under ANS control and these changes can be quantified using IRT. A combination of IRT and HRV is a non-invasive way to measure ANS activity and assess acute welfare impacts of husbandry practices in cattle. Further research using pharmacological inhibition and stimulation of the ANS activity would be beneficial to fully understand the underlying regulatory mechanisms of the eye temperature and HRV responses in cattle and other species during stress and/or pain. The full capability of IRT and HRV for detection of disease and emotional states and the effects of different intensities of pain, individual traits and previous experience also deserve attention.
Частини книг з теми "Temperature measurement through infrared thermography":
1
Barreira, Eva, and Ricardo M. S. F. Almeida. "Measurement of Surface Temperature Using Different Devices." In Infrared Thermography for Building Moisture Inspection, 7–28. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-75386-7_2.
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Müller, W., H. Piazena, A. R. Thomsen, and Peter Vaupel. "Thermography and Thermometry in wIRA-Hyperthermia." In Water-filtered Infrared A (wIRA) Irradiation, 55–67. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92880-3_4.
Анотація:
AbstractContact-free temperature determination is based on the measurements of electromagnetic radiation. The corresponding physical laws are related to the properties of black bodies. This background allows for the development of thermometric and thermographic systems for remote temperature measurements. Precise absolute temperature data, required in hyperthermia, do not only depend on the technical quality of the systems (hardware and software) and their calibration, but also depend on accurate determination of the emissivity of human skin. Pyrometers are restricted to temperature measurements within a small area (measurement spot), while thermographic cameras allow measurements across a relatively large region on the target area in real time. The subdivision of the IR image into spatially separated pixels allows access to temperature data of small areas on the skin and thus combines thermometry and thermography. Quality assurance standards of the European Society of Hyperthermic Oncology for water-filtered IR-A-hyperthermia (wIRA-HT) are met, except for the accuracy of the absolute temperature. Since the relation between the temperatures at the skin surface and in deeper tissue layers, considering irradiation and heating time, in wIRA-HT can be assessed, the temperature needed for efficient thermal treatment of superficial tumors within superficial tissue layers can therefore be achieved in a controlled manner.
3
Jones, J. P., S. P. Brookes, M. T. Whittaker, R. J. Lancaster, and B. Ward. "Assessment of Infrared Thermography for Cyclic High-Temperature Measurement and Control." In Evaluation of Existing and New Sensor Technologies for Fatigue, Fracture and Mechanical Testing, 186–206. 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959: ASTM International, 2015. http://dx.doi.org/10.1520/stp158420140080.
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Thomsen, A. R., M. R. Saalmann, N. H. Nicolay, A. L. Grosu, and Peter Vaupel. "Temperature Profiles and Oxygenation Status in Human Skin and Subcutis Upon Thermography-Controlled wIRA-Hyperthermia." In Water-filtered Infrared A (wIRA) Irradiation, 69–80. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92880-3_5.
Анотація:
AbstractEfficacy of wIRA immediately followed by hypofractionated radiation in the treatment of locally recurrent breast cancer and other superficial tumors is documented. A prerequisite for the additive and synergistic radiosensitizing properties of hyperthermia is the assessment of resulting temperatures of tumors and normal tissues. To assess the role of hyperthermia in reversing tumor hypoxia through its effects on local blood flow, oxygen profiles in skin, subcutis, and superficial tumors have been additionally assessed during mild hyperthermia (39–43 °C).Upon wIRA-exposure, skin surface temperatures increased from 35 to 41.6 °C within 5–12 min. Maximum temperatures of 42 °C were found in subepidermal regions, with a steady decline in deeper layers reaching 40.1 °C at a depth of 20 mm. Heating was accompanied by increases in tissue oxygen tensions. Effective hyperthermia levels (≥ 39 °C) were established in depths up to 25 mm. Following wIRA exposure, tissue temperatures returned to pretreatment levels within a few minutes, with the decay time depending on tissue depths, while pO2 values remained on therapeutical levels for 30–60 min postheat, outlasting the period needed for subsequent radiotherapy. Monitoring in the upper dermis layer of skin and recurrent breast cancers confirmed the improved O2 status during wIRA exposure and outlasted the time needed for subsequent radiotherapy.
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Elfner, Maximilian, Hans-Jörg Bauer, and Achmed Schulz. "Surface Temperature Measurement on Complex Topology by Infrared Thermography." In The Art of Measuring in the Thermal Sciences, 241–65. CRC Press, 2020. http://dx.doi.org/10.1201/9780429201622-13.
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Dey, Nilanjan, Amira S. Ashour, and Afnan S. Althoupety. "Thermal Imaging in Medical Science." In Computer Vision, 1109–32. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-5204-8.ch046.
Анотація:
Thermal imaging is a non-destructive, non-contact and rapid system. It reports temperature through measuring infrared radiation emanated by an object/ material surface. Automated thermal imaging system involves thermal camera equipped with infrared detectors, signal processing unit and image acquisition system supported by computer. It is elaborated in wide domains applications. Extensive focus is directed to the thermal imaging in the medical domain especially breast cancer detection. This chapter provided the main concept and the different applications of thermal imaging. It explores and analyses several works in the light of studding the thermograph. It is an effective screening tool for breast cancer prediction. Studies justify that thermography can be considered a complementary tool to detect breast diseases. The current chapter reviews many usages and limitations of thermography in biomedical field. Extensive recommendations for future directions are summarized to provide a structured vision of breast thermography.
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Ricci, Gisele Dela, Larissa José Parazzi, Flavia Santos, Rafael Teixeira de Sousa, and Késia Oliveira da Silva Miranda. "USE OF INFRARED THERMOGRAPHY IN POULTRY AS A NON-INVASIVE METHOD OF HEALTH ASSESSMENT." In Ciências Agrárias: tecnologia, sustentabilidade e inovação - Volume 1, 251–64. Editora Científica Digital, 2024. http://dx.doi.org/10.37885/240115464.
Анотація:
Intensive broiler chicken production is characterized by the restricted space that limits the expression of natural behaviors and hinders the thermal comfort of the animals. To maintain the competitiveness of poultry production, it is necessary to adapt the facilities and management to overcome the harmful effects of critical environmental factors, such as high temperatures and relative humidity of the air. Seeking to evaluate the facilities and their interference in the health and comfort of animals through practical and fast methods, the use of infrared thermography is used. Thermography is a non-invasive method that allows accurate analysis of body temperature. The objective of this review was to demonstrate the importance of using thermography in poultry farming in quick interventions aiming to guarantee animal welfare and adequate production economy. Studies show that in poultry farming, the use of thermographic cameras is efficient to measure the surface temperature of birds, with the surface temperature also correlated with the surface temperatures of the facilities and inside the incubator itself. It is concluded that the use of non-invasive methods of heat stress detection is necessary for quick interference to prevent animals from remaining in thermal discomfort, reducing their quality of life and productivity. It has been proven that the evaluation by means of a thermographic camera for broilers is efficient, as it allows the diagnosis of diseases, heat stress, allowing quick intervention.
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Haddad, Denise Sabbagh, Marcos Leal Brioschi, and Emiko Saito Arita. "Thermal Evaluation of Myogenous Temporomandibular Disorders and Myofascial Trigger Points in the Masticatory Muscles." In Oral Healthcare and Technologies, 329–50. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-1903-4.ch008.
Анотація:
It is known that the myofascial trigger points (MTP) and myogenous temporomandibular disorders (TMDs) cause regional sympathetic hyperactivity in local temperature due to the cutaneous vasomotor activity and, for detection of functional changes, thermography is used as a complementary diagnostic imaging method. This chapter intends to study two masticatory muscles, masseter and anterior temporalis, in measurement of the cutaneous temperature of volunteers with and without myogenous TMD and MTP. Results: The temperature levels measured at both muscles regions in myogenous TMD volunteers were significantly lower than those measured in controls. Infrared imaging indicated differences between referred and local pain in MTPs of 0.5ºC. Conclusions: Infrared imaging measurements seem to indicate that it can be used as an aid in complimentary diagnosing of TMDs and MTPs in masticatory muscles.
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Haddad, Denise Sabbagh, Marcos Leal Brioschi, and Emiko Saito Arita. "Thermal Evaluation of Myogenous Temporomandibular Disorders and Myofascial Trigger Points in the Masticatory Muscles." In Innovative Research in Thermal Imaging for Biology and Medicine, 119–40. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-2072-6.ch006.
Анотація:
It is known that the myofascial trigger points (MTP) and myogenous temporomandibular disorders (TMDs) cause regional sympathetic hyperactivity in local temperature due to the cutaneous vasomotor activity and, for detection of functional changes, thermography is used as an complementary diagnostic imaging method. This chapter intends to study two masticatory muscles, masseter and anterior temporalis, in measurement of the cutaneous temperature of volunteers with and without myogenous TMD and MTP. Results: The temperature levels measured at both muscles regions in myogenous TMD volunteers were significantly lower than those measured in controls. Infrared imaging indicated differences between referred and local pain in MTPs of 0.5ºC. Conclusions: Infrared imaging measurements seem to indicate that it can be used as an aid in complimentary diagnosing of TMDs and MTPs in masticatory muscles.
10
Stoynova, Anna, Irina Aleksandrova, and Anatoliy Aleksandrov. "Remote Nondestructive Thermal Control of Elastic Abrasive Cutting." In Tribology [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.103115.
Анотація:
High temperatures during abrasive cutting lead to increased harmful gas emissions released into the environment, intensified cut-off wheel wear, microstructural changes in the machined material, and occurrence of thermal flaws. Temperature measurement in abrasive cutting is difficult due to the small size of the heated area (only tenths of mm2), high temperatures (above 1000°C), continuous change of the conditions within one cut-off cycle, large temperature gradient (more than 200°C), high cutting speed (above 50 m/s) and high mechanical load. The infrared thermography (IRT) application for thermal control of elastic abrasive cutting have been studied. The performed thermal measurements have been verified with the results obtained from the temperature models of workpiece, cut-off wheel, and cut piece depending on the conditions in elastic abrasive cutting of two structural steels C45 and 42Cr4. The parameters of effective abrasive cutting have been determined by applying multi-objective optimization.
Тези доповідей конференцій з теми "Temperature measurement through infrared thermography":
1
Lehtiniemi, R., C. M. Fager, and J. Rantala. "True temperature measurement of electronics through infrared transparent materials." In 1998 Quantitative InfraRed Thermography. QIRT Council, 1998. http://dx.doi.org/10.21611/qirt.1998.028.
2
van Haren, F. G. A. M., L. Kadic, and J. J. Driessen. "Evaluation of the success of sciatic nerve blockade by skin temperature measurement through infrared thermography." In 2014 Quantitative InfraRed Thermography. QIRT Council, 2014. http://dx.doi.org/10.21611/qirt.2014.022.
3
Baczkowski, Lény, Franck Vouzelaud, Dominique Carisetti, Nicolas Sarazin, Jean-Claude Clément, Jean-Claude Jacquet, Christophe Gaquiére, Benoit Lambert, and Laurent Brunel. "IR Thermography for Temperature Measurements and Fault Location on AlGaN/GaN HEMTs and MMICs." In ISTFA 2015. ASM International, 2015. http://dx.doi.org/10.31399/asm.cp.istfa2015p0253.
Анотація:
Abstract This paper shows a specific approach based on infrared (IR) thermography to face the challenging aspects of thermal measurement, mapping, and failure analysis on AlGaN/GaN high electron-mobility transistors (HEMTs) and MMICs. In the first part of this paper, IR thermography is used for the temperature measurement. Results are compared with 3D thermal simulations (ANSYS) to validate the thermal model of an 8x125pm AIGaN/GaN HEMT on SiC substrate. Measurements at different baseplate temperature are also performed to highlight the non-linearity of the thermal properties of materials. Then, correlations between the junction temperature and the life time are also discussed. In the second part, IR thermography is used for hot spot detection. The interest of the system for defect localization on AIGaN/GaN HEMT technology is presented through two case studies: a high temperature operating life test and a temperature humidity bias test.
4
Prakash, Raghu V. "Studies on Fatigue Damage Progression in Post-Impacted CFRP Composite Through Passive Thermography and Stiffness Measurement." In ASME 2022 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/imece2022-95102.
Анотація:
Abstract Reinforced polymer composite materials are widely used in several areas of aerospace, other civilian structures, in view of tailor-suiting to the design requirements. During service, barely visible damages are induced due to accidental tool drops, hail storms and bird strikes, and they can propagate due to fatigue cycles applied during a mission. The damage progression can result in loss of load carrying capacity and ultimate failure. Damage progression due to fatigue in composites has been an important aspect of study as it can result in loss of load carrying capacity and ultimate failure. In this study, the stiffness degradation in a quasi-isotropic carbon fiber polymer composite specimen subjected to FALSTAFF (Fighter Aircraft Loading Standard for Fatigue) spectrum was assessed, after it has been subjected to a drop-impact. Fatigue test was carried out post-impact till specimen failure, which meant testing over several days. The unloading stiffness of the specimen was estimated from the load versus displacement data that was recorded after every block of FALSTAFF loading. It is observed that the stiffness of the specimen degrades with the progression of damage. An Infrared thermal imaging camera (TIM 160 from MicroEpsilon, Germany) was used in passive mode to monitor the temperature changes in the specimen during fatigue cycling. In view of the long duration of fatigue test spanning several days and IR camera cooling requirements, the test was periodically interrupted after certain blocks of FALSTAFF loading. Temperature data during fatigue cycling was compared with stiffness degradation to understand the fatigue damage progression in specimens. The first derivative of temperature response data was found to have a reasonable correlation with the first derivative of stiffness.
5
Sinofsky, Edward. "Internal biological tissue temperature measurements using zirconium fluoride IR fibers." In International Laser Science Conference. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/ils.1986.fb4.
Анотація:
The availability of zirconium fluoride fibers with improved midinfrared transmission has extended the range of remote thermography. One application is measurement of the internal temperature of biological tissue during and after exposure to laser energy. Such measurements are important for verification and calibration of predictive thermal models allowing rational selection of such parameters as power, wavelength, pulse duration, and total fluence. This technique may also help to determine when vaporization will occur with a minimum zone of thermal injury. The infrared signal can be sensed by circuitry to terminate the exposure automatically when the selected tissue temperature is reached. This scheme should be more accurate than visual interpretation of the degree of blanching. We report predictions of the signal level as a function of tissue temperature for detection through the fiber by a thermoelectrically cooled lead selenide photodetector. We also explore the resolution limits in space, time, and temperature, and compare our measured values with results of modeling calculations performed at USCI.
6
Ekkad, Srinath V., Shichuan Ou, and Richard B. Rivir. "A Transient Infrared Thermography Method for Simultaneous Film Cooling Effectiveness and Heat Transfer Coefficient Measurements From a Single Test." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-54236.
Анотація:
In film cooling situations, there is a need to determine both local adiabatic wall temperature and heat transfer coefficient to fully assess the local heat flux into the surface. Typical film cooling situations are termed three temperature problems where the complex interaction between the jets and mainstream dictates the surface temperature. The coolant temperature is much cooler than the mainstream resulting in a mixed temperature in the film region downstream of injection. An infrared thermography technique using a transient surface temperature acquisition is described which determines both the heat transfer coefficient and film effectiveness (non-dimensional adiabatic wall temperature) from a single test. Hot mainstream and cooler air injected through discrete holes are imposed suddenly on an ambient temperature surface and the wall temperature response is captured using infrared thermography. The wall temperature and the known mainstream and coolant temperatures are used to determine the two unknowns (heat transfer coefficient and film effectiveness) at every point on the test surface. The advantage of this technique over existing techniques is the ability to obtain the information using a single transient test. Transient liquid crystal techniques have been one of the standard techniques for determining h and η for turbine film cooling for several years. Liquid crystal techniques do not account for non uniform initial model temperatures while the transient IR technique measures the entire initial model distribution. The transient liquid crystal technique is very sensitive to the angle of illumination and view while the IR technique is not. The IR technique is more robust in being able to take measurements over a wider temperature range which improves the accuracy of h and η. The IR requires less intensive calibration than liquid crystal techniques. Results are presented for film cooling downstream of a single hole on a turbine blade leading edge model.
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Cruz, Carlos A., Fernando Raffan, Christopher Cadou, and Andre´ W. Marshall. "Characterizing Slot Film Cooling Through Detailed Experiments." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-15899.
Анотація:
With the ever increasing operating temperatures of gas turbine engines, the surface cooling of hot section components remains a primary consideration in propulsion system design. At the same time, numerical tools are being used more extensively for hot-section flow-path design. Recognizing the need for detailed data to help develop and validate these numerical tools, the present study focuses on characterizing near-wall mixing and heat transfer in a canonical 2D slot film cooling configuration. The lack of comprehensive and detailed experimental film cooling data under realistic temperature and blowing ratio conditions has led the authors to develop and implement a unique experimental facility that will allow measuring velocity and temperature profiles as well as surface temperatures and heat transfer at the wall under adiabatic and isothermal conditions. This hot wind tunnel facility provides optical access for Laser Doppler Velocimetry (LDV) near the wall and wall surface temperature distribution with infrared (IR) thermography. In addition to these non-intrusive diagnostics, the gas-phase temperature is measured with a minimally intrusive micro-thermocouple probe with fast response time and high frequency sampling. The performance of selected film cooling effectiveness scaling laws is analyzed. The thermal and momentum mixing of the film described in terms of temperature and velocity profiles and associated statistics. These detailed measurements are hoped to provide guidance and validation for CFD model developers.
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Natarajan, Shweta, Bobby G. Watkins, Vinod Adivarahan, Asif Khan, and Samuel Graham. "Thermal Characterization of Discrete Device Layers in AlxGa1−xN Based Ultraviolet Light Emitting Diodes." In ASME 2012 Third International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/mnhmt2012-75146.
Анотація:
The temperature rise in LEDs is an important parameter that must be determined for both thermal management and device lifetime/reliability assessment. Commonly used indirect methods of measuring the device temperature either estimate the multiple quantum well (MQW) temperature based on measuring temperature dependent device characteristics (e.g., forward voltage and electroluminescence methods), or they measure the average temperature across the device structure using optical methods such as infrared (IR) thermography and thermoreflectance. However, none give true insight into the vertical distribution of temperature in these structures. In this study, Raman spectroscopy is applied for the first time to operating UV LEDs to give the temperature rise in discrete layers within the LED device structure, going from the growth substrate to layers adjacent to theMQWs. Comparisons are made with IR themography to contrast with this depth sensitive measurement technique. It was observed that the peak temperatures in the device were much higher than the temperatures indicated by IR while the averaged temperatures through the structure compared favorably. Additional comparisons to electroluminescence measurements were also made which compared favorably with the peak temperatures found by Raman Spectroscopy.
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Laveau, Benoit, Reza S. Abhari, Michael E. Crawford, and Ewald Lutum. "High Resolution Heat Transfer Measurements on the Stator Endwall of an Axial Turbine." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26105.
Анотація:
In order to continue increasing the efficiency of gas turbines, an important effort is made on the thermal management of the turbine stage. In particular understanding and accurately estimating the thermal loads in a vane passage is of primary interest to engine designers looking to optimize the cooling requirements and ensure the integrity of the components. This paper focuses on the measurement of endwall heat transfer in a vane passage with a 3D airfoil shape and cylindrical endwalls. It also presents a comparison with predictions performed using an in-house developed RANS solver featuring a specific treatment of the numerical smoothing using a flow adaptive scheme. The measurements have been performed in a steady state axial turbine facility on a novel platform developed for heat transfer measurements and integrated to the nozzle guide vane row of the turbine. A quasi-isothermal boundary condition is used to obtain both the heat transfer coefficient and the adiabatic wall temperature within a single measurement day. The surface temperature is measured using infrared thermography through small view ports. The infrared camera is mounted on a robot-arm with six degrees of freedom to provide high resolution surface temperature and a full coverage of the vane passage. The paper presents results from experiments with two different flow conditions obtained by varying the mass flow through the turbine: measurements at the design point (ReCax = 7,2.105) and at a reduced mass flow rate (ReCax = 5,2.105). The heat transfer quantities, namely the heat transfer coefficient and the adiabatic wall temperature, are derived from measurements at 14 different isothermal temperatures. The experimental data are supplemented with numerical predictions that are deduced from a set of adiabatic and diabatic simulations. In addition, the predicted flow field in the passage is used to highlight the link between the heat transfer patterns measured and the vortical structures present in the passage.
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Naveira-Cotta, Carolina P., Helcio R. B. Orlande, Renato M. Cotta, and Jeziel S. Nunes. "Integral Transforms, Bayesian Inference, and Infrared Thermography in the Simultaneous Identification of Variable Thermal Conductivity and Diffusivity in Heterogeneous Media." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22511.
Анотація:
This work deals with the simultaneous estimation of spatially variable thermal conductivity and diffusivity for one-dimensional heat conduction in heterogeneous media. The direct problem solution is analytically obtained via integral transforms and the related eigenvalue problem is solved by the Generalized Integral Transform Technique (GITT). The inverse problem is handled by Bayesian inference through a Markov Chain Monte Carlo (MCMC) method. Instead of seeking the function estimation in the form of a sequence of local values for the thermal properties, an alternative approach is utilized here, which is based on the eigenfunction expansion of the thermal conductivity and diffusivity themselves. Then, the unknown parameters become the corresponding expansion coefficients. In addition, the inverse analysis is performed on the transformed temperature field, instead of employing the actual local temperature measurements, thus promoting a significant data reduction through the integral transformation of the experimental measurements. A demonstration experiment is built involving a partially heated thin bakelite plate. Temperature measurements obtained via infrared thermography are used in the inverse analysis.