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Dissertations / Theses on the topic 'Thermography'
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1
Purslow, Christine. "Dynamic ocular thermography." Thesis, Aston University, 2005. http://publications.aston.ac.uk/14563/.
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The ability to measure ocular surface temperature (OST) with thermal imaging offers potential insight into ocular physiology that has been acknowledged in the literature. The TH7102MX thermo-camera (NEC San-ei, Japan) continuously records dynamic information about OST without sacrificing spatial resolution. Using purpose-designed image analysis software, it was possible to select and quantify the principal components of absolute temperature values and the magnitude plus rate of temperature change that followed blinking. The techniques was examined for repeatability, reproducibility and the effects of extrinsic factors: a suitable experimental protocol was thus developed. The precise source of the measured thermal radiation has previously been subject toe dispute: in this thesis, the results of a study examining the relationships between physical parameters of the anterior eye and OST, confirmed a principal role for the tear film in OST. The dynamic changes in OST were studied in a large group of young subjects: quantifying the post-blink changes in temperature with time also established a role for tear flow dynamics in OST. Using dynamic thermography, the effects of hydrogel contact lens wear on OST were investigated: a model eye for in vivo work, and both neophyte and adapted contact lens wearers for in vivo studies. Significantly greater OST was observed in contact lens wearers, particularly with silicone hydrogel lenses compared to etafilcon A, and tended to be greatest when lenses had been worn continuously. This finding is important to understanding the ocular response to contact lens wear. In a group of normal subjects, dynamic thermography appeared to measure the ocular response to the application of artificial tear drops: this may prove to be a significant research and clinical tool.
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Larsen, Cory A. "Document Flash Thermography." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/1018.
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This thesis presents the application of ash thermography techniques to the analysis of documents. The motivation for this research is to develop the ability to non-destructively reveal covered writings in archaeological artifacts such as the Codex Selden or Egyptian car- tonnage. Current common signal processing techniques are evaluated for their effectiveness in enhancing subsurface writings found within a set of test documents. These processing techniques include: false colorization, contrast stretching, histogram equalization, median altering, Gaussian low-pass altering, layered signal reconstruction and thermal signal reconstruction (TSR), several contrast image definitions, differential absolute contrast (DAC), correlated contrast, derivative images, principal component thermography (PCT), dynamic thermal tomography (DTT), pulse phase thermography (PPT), tying-correlation analysis (FCA), Hough transform thermography (PTHTa), and transmission line matrix tying algorithm (TLMFa). New processing techniques are developed and evaluated against the existing techniques. The ability of ash thermography coupled with processing techniques to reveal subsurface writings and document strikeouts is evaluated. Flash thermography parameters are evaluated to determine most eeffective value for the document. In summary, this thesis reports the following contributions to the existing scientific knowledge: 1. A comprehensive analysis of existing pulsed thermography processing techniques. 2. New pulsed thermography processing techniques that improve upon the results of the existing techniques were developed. 3. A proof-of-concept for detecting subsurface ink writings in documents. 4. Varies the capability of pulsed thermography techniques to detect document strike- outs. 5. Demonstrates the ability to enhance surface writings based on differences in thermal characteristics when optical characteristics do not vary significantly. 6. Demonstrates that pulsed thermography significantly improves upon multi-spectral imaging for subsurface and surface writing enhancement. 7. Provides an evaluation of ash thermography parameters for the most effective document imaging.
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Ziegler, Mathias. "Thermography of semiconductor lasers." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2009. http://dx.doi.org/10.18452/15944.
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Halbleiterlaser stellen mit über 70% Wirkungsgrad einzigartig effiziente Lichtquellen dar. Dennoch ist ihre zuverlässige Nutzung, insbesondere im Bereich hoher Leistungsdichten, von thermischen Limitierungen geprägt. Einen grundlegenden Beitrag zu deren physikalischen Verständnis leistet die Analyse der thermischen Eigenschaften und Degradationsprozesse solcher Bauelemente. In dieser Arbeit wird hierzu die Thermographie als innovative Analysemethode untersucht. Das Plancksche Strahlungsgesetz erlaubt die radiometrische Ermittlung der Temperatur. Die wichtige physikalische Kenngröße Emissivität wird in dieser Arbeit für Halbleiter und Halbleiterlaserstrukturen spektral gemessen und auf fundamentale physikalische Eigenschaften zurückgeführt. Auf dieser Grundlage werden methodische Aspekte der Thermographie diskutiert, welche durch den thermischen Hintergrund und die teilweise Transparenz der Halbleitermaterialien geprägt sind. Die daraus folgenden analytischen Fähigkeiten erlauben unter anderem die orts- und zeitaufgelöste Bestimmung der thermischen Eigenschaften von komplexen Hochleistungslasern unterschiedlichster Bauart. Darüber hinaus ermöglicht die Kenntnis der beteiligten thermischen Zeitkonstanten die Extraktion von lokalen Überhöhungen in der Infrarotemission, deren Zusammenhang zur Degradation der Bauelemente untersucht wird. Eine grundsätzliche Begrenzung der Ausgangsleistung ist durch einen abrupten Degradationsprozess gegeben, welcher maßgeblich durch eine Reabsorption der Laserstrahlung an der Frontfacette verursacht wird. Mithilfe einer kombinierten Thermographie-Nahfeld-Messung wird dieser Prozess orts- und zeitaufgelöst analysiert. Die Erweiterung des Messfensters zu kürzeren Wellenlängen hin erlaubt die Detektion strahlender Übergänge unter Einbeziehung von Defektzentren welche als strahlende Signaturen von graduellen Degradationsprozessen aufzufassen sind.Semiconductor lasers are unequaled efficient light sources, reaching efficiencies of more than 70%. Nevertheless, thermal limits govern their reliable application, in particular in the field of high power densities. The analysis of thermal properties and degradation processes in such devices contributes essentially to the understanding of these limits. This work exploits thermography as an innovative analytical technique for such purpose. Planck''s law allows for a radiometric detection of temperatures. In this work, the important physical parameter emissivity is measured spectrally resolved for both semiconductors and semiconductor laser structures and is related to fundamental physical properties. Based on that, methodological aspects are discussed, which are affected on the one hand by the omnipresent thermal radiation and on the other hand by the partial transparency of the semiconductor materials. The resulting analytical capacities allow, for instance, for the determination of the thermal properties of complex high-power lasers of a wide range of different designs in a spatio-temporally resolved fashion. Furthermore, does the knowledge of the involved thermal time constants allow for an extraction of localized peaks of the infrared emission that is analyzed for its relationship with device degradation. The output power of high-power devices is fundamentally limited by the catastrophic optical damage, an abrupt degradation process that is induced significantly by reabsorption of laser radiation at the front facet. This process is analyzed spatio-temporally resolved with help of a combined thermography and optical near-field technique. Extending the detection range down to shorter wavelengths allows for imaging of radiative transitions that are related to defect centers, which are interpreted as radiative signatures of gradual device degradation processes.
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Monchau, Jean-Pierre. "Mesure d'émissivité pour la thermographie infrarouge appliquée au diagnostic quantitatif des structures." Thesis, Paris Est, 2013. http://www.theses.fr/2013PEST1128/document.
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La thermographie infrarouge constitue un outil de diagnostic très utile dans le domaine du bâtiment et du génie civil. Cependant un diagnostic quantitatif reste difficile, et l'émissivité des surfaces étudiées joue un rôle important. Le présent travail est une étude sur la mesure d'émissivité pour le diagnostic quantitatif des structures par thermographie. Un des enjeux est de compléter une base de données d'émissivité pour des matériaux du bâtiment et du génie civil ; pour cela il a été nécessaire de développer des appareils de mesure portables. Deux appareils ont été développés au CERTES, utilisant des méthodes indirectes. Ces méthodes consistent à mesurer la réflexion d'un flux infrarouge modulé et nécessite une référence de réflectance connue. Le premier appareil module le flux par modulation lente de température (mesure en 16mn) ; il est adapté aux surfaces diffusantes et hétérogènes comme les bétons bitumineux et les matériaux de construction du bâtiment. L'autre appareil utilise un système d'écran permettant une modulation plus rapide (mesure en quelques secondes). Il est plus polyvalent. Il est aussi plus facilement transportable et permet également d'obtenir une évaluation du caractère plus ou moins spéculaire de la surface. Ces deux appareils couvrent au choix une bande spectrale large (1 à 40µm) pour évaluer les propriétés radiatives des surfaces et une bande étroite (8 à 14µm) adaptée à la sensibilité des caméras infrarouges. Une étude comparative sur les mesures d'émissivité a été entreprise avec le LNE (Laboratoire National de Métrologie et d'Essais). Les échantillons utilisés pour cette étude comparative ont permis de tester les différents dispositifs pour des matériaux ayant des propriétés radiatives très variées. Des mesures ont été effectuées au laboratoire et sur site sur une large gamme de matériaux usuels du bâtiment et du génie civilThermography is a very useful diagnosis tool in buildings and civil engineering structures. However quantitative diagnosis remains difficult, and having accurate values of surface emissivity is an important factor. The present work is a study about emissivity measurement for quantitative diagnosis with thermography. We needed accurate measurement of the emissivity of a number of civil engineering materials, in order to create a database. Thus, it was necessary to develop new portable measurement devices. Two devices using an indirect measurement method were developed at CERTES laboratory. The method uses the measurement of the reflectivity from a modulated IR source and requires calibration with a highly reflective surface. The first device uses a low-frequency, thermal modulation well-adapted to laboratory measurements, whereas the second one is a portable system using a mechanical modulation at a faster frequency, more appropriate to outdoor measurements. Both devices allow measurements in the broad (1—50µm) and narrow (8—14µm) bands. Experiments were performed on a large number of materials commonly used in buildings and civil engineering structures. The final objective of this work is to build a database of emissivity for these materials. A comparison of laboratory and on-site measurements of emissivity values obtained in both spectral bands is presented along with an estimation and an analysis of measurement uncertainties. A comparative study with measurement obtained at LNE (Laboratoire National de Métrologie et d'Essais, French laboratory of metrology) was performed, using a range of materials with widely different radiative properties. An analysis of discrepancies and their possible causes is presented
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Moussa, Wael. "Thermography-Assisted Bearing Condition Monitoring." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31379.
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Abstract
Despite the large amount of research work in condition based maintenance and condition monitoring methods, there is still a need for more reliable and accurate methods.
The clear evidence of that need is the continued dependence on time based maintenance, especially for critical applications such as turbomachinery and airplane engines. The lack of accurate condition monitoring systems could lead to not only the unexpected failures as well as the resulting hazards and repair costs, but also a huge waste of material and time because of unnecessary replacement due to false alarms and unnecessary repair and maintenance.
Temperature change is a phenomenon that accompanies every dynamic activity in the universe. However, it has not been adequately exploited for mechanical system condition monitoring. The reason is the slow response of current temperature monitoring systems compared to other condition monitoring methods such as vibration analysis. Many references inferred that the change in temperature is not sensible until approaching the end of the monitored component life and even the whole system life (Kurfess, et al., 2006; Randall, 2011; Patrick, et al., March 7-14, 2009).
On the other hand, the most commonly used condition monitoring method, i.e., vibration analysis, is not free from pitfalls. Although vibration analysis has shown success in detecting some bearing faults, for other faults like lubrication problems and gradual wear it is much less effective. Also, it does not give a reliable indication of fault severity for many types of bearing faults.
The advancement of thermography as a temperature monitoring tool encourages the reconsideration of temperature monitoring for mechanical system fault detection. In addition to the improved accuracy and responsiveness, it has the advantage of non-contact monitoring which eliminates the need for complex sensor mounting and wiring especially for rotating components.
Therefore, in current studies the thermography-based monitoring method is often used either as a distinct method or as a complementary tool to vibration analysis in an integrated condition monitoring system. The main objectives of this study are hence to:
1. Define heat sources in the rolling element bearings and overview two of the most famous bearing temperature calculation methods.
2. Setup a bearing test rig that is equipped with both vibration and temperature monitoring systems.
3. Develop a temperature calculation analytical model for rolling element bearing that include both friction calculation and heat transfer models. The friction calculated by the model will be compared to that calculated using the pre-defined empirical methods. The heat transfer model is used for bearing temperature calculation that will be compared to the experimental measurement using different temperature monitoring devices.
4. Propose a new in-band signal enhancement technique, based on the synchronous averaging technique, Autonomous Time Synchronous Averaging (ATSA) that does not need an angular position measuring device. The proposed method, in addition to the Spectral Kurtosis based band selection, will be used to enhance the bearing envelope analysis.
5. Propose a new method for classification of the bearing faults based on the fault severity and the strength of impulsiveness in vibration signals. It will be used for planning different types of tests using both temperature and vibration methods.
6. Develop and experimentally test a new technique to stimulate the bearing temperature transient condition. The technique is supported by the results of finite element modeling and is used for bearing temperature condition monitoring when the bearing is already running at thermal equilibrium condition.
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Li, Zheng Ph D. Massachusetts Institute of Technology. "Computational Raman imaging and thermography." Thesis, Massachusetts Institute of Technology, 2021. https://hdl.handle.net/1721.1/130673.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, February, 2021Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 185-201).
Thermography tools that perform accurate temperature measurements with nanoscale resolution are highly desired in our modern society. Although researchers have put extensive efforts in developing nanoscale thermography for more than three decades and a significant amount of achievements have been made in this field, the mainstream thermography tools have not fully met the requirements from the industry and the academia. In this thesis, we present our home-built Raman microscope for Raman imaging and thermography. The performance of this instrument is enhanced by computational approaches. The body of the thesis will be divided into three parts. First, the instrumentation of our setup are introduced. Second, we present the results of Raman imaging with computational super-resolution techniques. Third, this instrument is used as a thermography tool to map the temperature profile of a nanowire device. These results provide insights in combining advanced instrumentation and computational methods in Raman imaging and Raman thermography for the applications in modern nano-technology.
by Zheng Li.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Materials Science and Engineering
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Morgan, P. B. "Ocular thermography in health and disease." Thesis, University of Manchester, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507520.
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There has been interest in ocular temperature for over a century, with the publication of a limited amount of literature over that time. This thesis reports on the development and utilisation of a system for the measurement of ocular surface temperature based on an advanced infrared detector. The development of a suitable protocol for the infrared imaging and temperature measurement of the eye was established. Results from the analysis of the ocular temperature of 98 normal subjects indicated that the temperature at the centre of the cornea was 31.68 ± 0.60°C (mean ± SD), and the mean ocular surface temperature (MOST) was 32.10 ± 0.53°C. This value rose with increasing room and oral temperature (both p< 0.0001) and decreased with corneal thickness (p< 0.05) and age (p< 0.01). Ninety five per cent of the subjects had an inter-ocular difference in MOST within 0.53°C. There was a positive relationship between the variation in temperature across the ocular surface and the distance between the corneal apex and a coronal plane through the limbus (p< 0.001). The effect on eye temperature of changes in the ocular blood, nerve and tear supplies was studied. Three of nine patients (33%) with unilateral inflammatory disease had ocular temperature outside the established normal limits. For the group of patients as a whole, the temperature of the affected eye was warmer than the fellow (32.40 ± 0.81°C compared with 32.10 ± 0.70°C; p< 0.05). In a further study, there was a significant negative relationship between the degree of stenosis of the carotid artery and eye temperature (p< 0.001). In the examination of two patients with Horner's syndrome, one demonstrated a difference in eye temperature (0.61°C) outside normal limits (0.53°C), with the affected eye being warmer.
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Fox, Matthew William. "Thermography approaches for building defect detection." Thesis, University of Plymouth, 2016. http://hdl.handle.net/10026.1/4304.
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Thermography is one technology, which can be used to detect thermally significant defects in buildings and is traditionally performed using a walk-through methodology. Yet because of limitations such as transient climatic changes, there is a key performance gap between image capture and interpretation. There are however new methodologies currently available, which actively address some of these limitations. By better understanding alternative methodologies, the performance gap can be reduced. This thesis contrasts three thermography methodologies (Walk-through, time-lapse and pass-by) to learn how they deal with limitations and address specific building defects and thermal performance issues. For each approach, practical methodologies were developed and used on laboratory experiments (hot plate) and real dwelling case studies. For the real building studies, 133 dwellings located in Devon and Cornwall (South West England) were studied; this sample represents a broad spectrum of construction types and building ages. Experiments testing these three methodologies found individual strengths and weaknesses for each approach. Whilst traditional thermography can detect multiple defects, characterisation is not always easy to achieve due to the effects of transient changes, which are largely ignored under this methodology. Time-lapse thermography allows the observation of transient changes from which more accurate assessment of defect behaviour can be gained. This is due to improved differentiation between environmental conditions (such as cloud cover and clear sky reflections), actual material thermal behaviour and construction defects. However time-lapse thermography is slow, complex and normally only observes one view. Walk-past thermography is a much faster methodology, inspecting up to 50 dwellings per survey session. Yet this methodology misses many potential defects due to low spatial resolutions, single (external only) elevation inspection and ignoring transient climate and material changes. The implications of these results for building surveying practice clearly indicate that for an improved defect characterisation of difficult to interpret defects such as moisture ingress, thermographers should make use of time-lapse thermography. A review of methodology practicalities illustrates how the need for improved characterisation can be balanced against time and resources when deciding upon the most suitable approach. In order to help building managers and thermographers to decide on the most suitable thermography approach, two strategies have been developed. The first combines different thermography methodologies into a phased inspection program, where spatial and temporal resolution increase with each subsequent thermography inspection. The second provides a decision-making framework to help select the most appropriate thermography methodology for a given scenario or defect.
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Zhang, Cheng. "Influence of surface roughness on thermography measurement." Thesis, Högskolan Väst, Avd för automationssystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-6842.
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This university Bachelor's Thesis was performed to explore the influence of surface roughness on the thermography measurement. Thermography is a non-destructive testing method which can be used to detect cracks. However, it is hard to define how the surface roughness influences the emissivity and the result of a thermography measurement, as well as how the angle of the excitation source influences the result. Therefore, this work aims to define how the heating angle and surface roughness influence the thermography measurement, define the relationship between surface roughness and emissivity for the same crack, and define the influence of the angles which composed of the heating source, the direction of crack and the direction of surface roughness on thermography measurement. In this report, the theories of radiation and Signal-to-noise ratio (SNR) were explained, clearly. Also, two kinds of experiments were set up. One is focus on how the heating angle influence the thermography measurement, the other is focus on how the angle of the heating source, in relation to the crack direction and the direction of surface roughness, influence the SNR value. The conclusions of these experiments are that the heating of a crack increases as the angle decreases (from wide side to narrow side) and the angle ofincreases (from horizontal to vertical). Moreover, the SNR value decreases as the surface roughness increases. For the same surface roughness, the SNR value increases with increased crack angle (0°, 45° or 90°) and with decreased sample position angle (horizontal, 45°or vertical). What is more, the higher surface roughness, the larger the influence of the crack angle and the sample position angle. Finally, when the surface is polish, the crack angle and the sample position angle does not have any influence.
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Schuricht, Paul Hans. "Liquid crystal thermography in high speed flows." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310549.
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Gaidos, Eric J. (Eric James). "Remote infrared thermography for boundary layer measurements." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/43129.
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Захарова, Вікторія Миколаївна, Виктория Николаевна Захарова, Viktoriia Mykolaivna Zakharova, and Godwin Nkeokelonye. "Temperature based technologies in thermography and cryomedicine." Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/13936.
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Hamzah, Ab Razak. "The application of transient thermography to defect detection." Thesis, University of Bath, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296326.
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Abdul-Razzak, M. M. "Picture processing and display methods for microwave thermography." Thesis, University of Leeds, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354033.
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Richenderfer, Andrew Jonathan. "Development of MiST-IR : multi-spectral infrared thermography." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/103700.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 91-92).
In this thesis, I present a new diagnostic technique for interrogating boiling heat transfer phenomena. The technique, called Multi-Spectral Infrared Thermography or MiST, builds on previous diagnostic techniques for measuring the 2-D wall temperature distribution or the 2-D phase distribution of the fluid above the surface. These methods make use of infrared thermography, a well developed practice involving the use of a high-speed infrared camera to collect visual data. By analyzing the data with both qualitative and quantitative tools, insights into boiling heat transfer mechanisms can be gained. In addition to the MiST technique, a refined infrared camera calibration model is presented for accurately determining the wall temperature. MiST is a new technique that allows for the simultaneous measurement of both the temperature distribution and the phase distribution. This is in sharp contrast to previous techniques which have only allowed the measurement of one or the other. MiST uses a highly engineered, semi-transparent, thin-film heater to enable the simultaneous measurement of the two properties. The heater separates the two signals, one from the temperature and one from the phase, by taking advantage of two regions of the electromagnetic spectrum. By spectrally separating the two signals, no limitation in resolution or field of view is made. The refined camera calibration model presented builds on previous work, which quantified the radiation captured by the camera and used a coupled radiation and conduction model to back out the complete axial temperature distribution within the heater. The new model refines the older version by taking into account spectrally varying optical properties within the heater. The spectral data is easily acquired with a Fourier transform infrared spectrometer, and fed into the radiation model for enhanced accuracy. The development of MiST presents new opportunities in boiling heat transfer for insight into a complex phenomena. The use of MiST in boiling and condensation experiments will lead to the development of new heat transfer models, and can provide high-resolution data for computational fluid dynamics models. MiST presents the logical progression forward in boiling diagnostic tools as it provides enhanced data acquisition opportunities when compared to it's legacy versions.
by Andrew Jonathan Richenderfer.
S.M.
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Roddis, W. M. Kim. "Concrete bridge deck assessment using thermography and radar." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14943.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1987.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Bibliography: leaves 263-272.
by W. M. Kim Roddis.
M.S.
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Tan, Li Li. "Assessment of dry eyes using ocular surface thermography." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/assessment-of-dry-eyes-using-ocular-surface-thermography(77e912eb-6a15-4ea1-8b2c-7ed9958591ec).html.
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Assessment and diagnosis of dry eye disease (DED) is a challenging task. The conventional ways of diagnosing DED are problematic due to their invasiveness, poor test reliability and significant test duration. Previously, ocular surface thermography has been shown to be able to detect early inflammation and dry eye. However, its diagnostic ability and ocular temperature metrics that can best diagnose DED are not clear. The objectives of this thesis were manyfold. First, the prevalence of dry eye in Singapore population was investigated as a helpful basis for the rest of the project. A cross-sectional dry eye survey was carried out using McMonnies dry eye questionnaire. Members of the public were interviewed at 46 (out of 62) selected mass rapid transit stations in Singapore and its vicinity. 1004 questionnaires were collected from participants aged 15 - 83 years and various ethnicity. Prevalence of symptomatic dry eye (SDE) was found to be 12.3% (about 0.5 million Singaporeans). Risk factors associated with SDE were found to be age, gender, ethnicity, hypertension and contact lens wear. Smoking was not associated with SDE.The main part of this thesis sought to evaluate the efficacy of ocular thermography in diagnosing DED. A new infrared detector (NEC Thermo Tracer TH 9260) with relatively high resolution was used. Inter-image, inter-occasion and inter-examiner repeatability was first studied on 21 healthy and 15 DED subjects. Ocular surface marking and ocular surface temperature (OST) acquisition was performed with a novel 'diamond' method using a custom-designed OST analysis V2 software. Ten out of the twelve tested OST indices were shown to be highly repeatable for three studied time points: 0 s, 5 s and 10 s. They were temperatures of the geometric center of the cornea (GCC), mean temperature (MOST) of the region of interest (ROI), maximum (MaxT) and minimum (MinT) temperatures of the ROI, extreme temporal (T1) and nasal conjunctiva (T4), mid temporal (CT) and nasal conjunctiva (CN) and temporal (LT) and nasal limbal (LN). Another 62 DED and 63 age- and sex-matched controls were then recruited and the ten static and dynamic OST indices were evaluated. Static measures were study of absolute OST at t = 0 s, 5 s and 10 s after eye opening. Dynamic measures were study of mean change and net change in OST over 10 s of sustained eye opening. Static measures on eight OST indices (GCC, MOST, MinT, MaxT, T4, CT, LT and LN) at t = 0 s, 5 s and 10 s and dynamic measures on two OST indices (T4 at 3 s onward and MaxT at 5 s onward) were found to be valuable in detecting DED. The temperature metrics (static and dynamic) were identified for further investigation. Thereafter, the diagnostic ability of the temperature metrics were evaluated singly and as combinations in terms of their area under the curve (AUC), Youden index and discrimination power. Receiver operating characteristic curves were plotted for each metric. Best detectors for DED were found to be the T4 temperature metrics: particularly T4-5 and T4-10 (i.e. absolute temperature of the extreme nasal conjunctiva at 5 s and 10 s). Values of T4-5 of < 34.8 °C were found to give sensitivity and specificity of 87.1% and 50.8% respectively and values of T4-10 of < 34.6 °C were found to give sensitivity and specificity of 77.6% and 61.9% respectively. The two temperature metrics had highest Youden index as compared to other metrics and were shown to be useful in view of AUC > 70% but of limited performance in view of their discrimination power. Nevertheless, measuring T4-5 and T4-10 was found to be comparable to other conventional methods for DED. T4-10 was better than T4-5 in view of higher AUC and Youden index. None of the tested dynamic metrics was good detector for DED and combining metrics were not able to increase the diagnostic ability. The last part of this thesis was to validate the effectiveness of some common conventional dry eye tests, to study their correlation with T4 temperature metrics and derive the best composite/combined tests for DED. Sixty two DED patients and 82 controls were studied. The conventional clinical tests examined were: symptom evaluation using McMonnies dry eye questionnaire (Mscore) and symptom count (Scount), fluorescein break-up time (FBUT) and corneal epithelial staining (CES), non-invasive break-up time (NIBUT) and tear meniscus height (TMH). Mscore and Scount was the best detectors for DED, followed by FBUT and CES. Discordance between signs and symptoms for DED was further confirmed. Combining CES with T4-10 (series) can be future objective tests for DED. Further research is warranted, particularly to (1) validate the ability of T4-10 as a stand-alone test for DED and (2) work out an algorithm and validate the diagnostic ability of the recommended combined test (CES and T4-10) using newly recruited subjects.
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Selva, Marti Salvador. "Aerial Thermography Inspections in Large-Scale PV Plants." Thesis, Högskolan Dalarna, Energiteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:du-28541.
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In order to successfully compete against the use of fossil fuels to generate electricity, one of the challenges in the photovoltaic (PV) business currently in focus is on the asset management of large PV plants, in which developing control techniques to prognosticate and evaluate the future energy performance will be essential. Infrared thermography inspections can give meaningful support to assess the quality and performance of PV modules. However, the implementation of a cost-effective method to scan and check huge PV plants represents different challenges, such as the cost and time of detecting PV module defects with their classification and exact localization within the solar plant. In this context, it has recently been investigated the potential of a new innovative technology in the PV plants monitoring operations by using drones. The main purpose of this work is to establish a scientific basis for the interpretation of thermographic images taken by drones, in particular, regarding the influence of thermographic irregularities which will negatively influence the performance of PV plants. The drone is employed to monitor PV modules conditions by using special thermography sensors mounted on it in order to scan images. The captured images are then automatically sent to a technical office database for the image processing software. This special software receives, stores and analyses the captured images to detect the specific defect on the PV modules. Then, all information is processed and reported to the final decision-making team to decide about the best solution for the particular degraded PV module, in relation with the requirements from the operation and maintenance (O&M) services. In this particularly study project of the inspected PV plant situated in the UK, which has been carried out by trained personnel at Quintas Energy (QE), the majority of identified faults, which influence the PV module performance (especially the power output significantly), are on a sub-panel level, either individual cells or uneven hot spots. There are also some modules with bypass diode faults as well as a string fault was detected. Such faults must be repaired by the PV module manufacturer, in relation to the manufacturer’s warranties, without any cost at all since the PV modules are indeed still in warranty. It has been concluded that, in comparison with traditional manned systems by using hand-held cameras, the main functionality of using drones is the early fault diagnosis which could reduce corrective maintenance activities, since defects are easily and quickly identified and, then, repaired. This fact could reduce defects to become more serious and, thus, more difficult to be repaired, along with their correspondent production losses and costs. QE has learned by making mistakes during this project study and gained experience of this unmanned aerial vehicles (UAV) technology. Currently, they are in the process of improving this technique and will continue to implement it to all their PV plants since the efficiency of PV systems can be significantly improved by appropriate use of O&M instruments and benefit from innovative monitoring tools, such as the unmanned aerial technology.
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Parvataneni, Rohit. "Principal component thermography for steady thermal perturbation scenarios." Connect to this title online, 2009. http://etd.lib.clemson.edu/documents/1263397875/.
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Cuibus, Lucian <1982>. "Applications of infrared thermography in the food industry." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5559/1/Cuibus_Lucian_Tesi.pdf.
Full textAbstract:
In the last 20-30 years, the implementation of new technologies from the research centres to the food industry process was very fast. The infrared thermography is a tool used in many fields, including agriculture and food science technology, because of it's important qualities like non-destructive method, it is fast, it is accurate, it is repeatable and economical. Almost all the industrial food processors have to use the thermal process to obtain an optimal product respecting the quality and safety standards. The control of temperature of food products during the production, transportation, storage and sales is an essential process in the food industry network. This tool can minimize the human error during the control of heat operation, and reduce the costs with personal.
In this thesis the application of infrared thermography (IRT) was studies for different products that need a thermal process during the food processing. The background of thermography was presented, and also some of its applications in food industry, with the benefits and limits of applicability. The measurement of the temperature of the egg shell during the heat treatment in natural convection and with hot-air treatment was compared with the calculated temperatures obtained by a simplified finite element model made in the past. The complete process shown a good results between calculated and observed temperatures and we can say that this technique can be useful to control the heat treatments for decontamination of egg using the infrared thermography. Other important application of IRT was to determine the evolution of emissivity of potato raw during the freezing process and the control non-destructive control of this process. We can conclude that the IRT can represent a real option for the control of thermal process from the food industry, but more researches on various products are necessary.
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Cuibus, Lucian <1982>. "Applications of infrared thermography in the food industry." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5559/.
Full textAbstract:
In the last 20-30 years, the implementation of new technologies from the research centres to the food industry process was very fast. The infrared thermography is a tool used in many fields, including agriculture and food science technology, because of it's important qualities like non-destructive method, it is fast, it is accurate, it is repeatable and economical. Almost all the industrial food processors have to use the thermal process to obtain an optimal product respecting the quality and safety standards. The control of temperature of food products during the production, transportation, storage and sales is an essential process in the food industry network. This tool can minimize the human error during the control of heat operation, and reduce the costs with personal.
In this thesis the application of infrared thermography (IRT) was studies for different products that need a thermal process during the food processing. The background of thermography was presented, and also some of its applications in food industry, with the benefits and limits of applicability. The measurement of the temperature of the egg shell during the heat treatment in natural convection and with hot-air treatment was compared with the calculated temperatures obtained by a simplified finite element model made in the past. The complete process shown a good results between calculated and observed temperatures and we can say that this technique can be useful to control the heat treatments for decontamination of egg using the infrared thermography. Other important application of IRT was to determine the evolution of emissivity of potato raw during the freezing process and the control non-destructive control of this process. We can conclude that the IRT can represent a real option for the control of thermal process from the food industry, but more researches on various products are necessary.
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Visentini, Roberta. "Étude expérimentale des transferts thermiques en ébullition transitoire." Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0106/document.
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L'ébullition est présente dans la vie de tous les jours et elle a été par conséquent le sujet de beaucoup d'études, mais pour la plupart en régimes stationnaires. Néanmoins, l'intérêt de connaître les caractéristiques de l'ébullition transitoire est aussi important notamment pour la prévention des accidents nucléaires majeurs. C'est justement dans l'optique de mieux comprendre les phénomènes d'ébullition qui se produisent lors d'un RIA (Accident d'Insertion de Réactivité) que cette thèse a été financée par l'IRSN. Le RIA est un accident qui peut résulter d'une défaillance du mécanisme de la grappe contrôlant la réaction nucléaire. La réaction s'emballe pendant quelques dizaines de millisecondes (pulse de puissance) provoquant une augmentation rapide de la température du crayon de combustible et donc l'évaporation du liquide qui l'entoure. Des tests ont été faits par le passé soit sur des crayons de combustibles, soit sur des tubes chauffés ayant les mêmes dimensions qu'un crayon, afin d'améliorer la connaissance de ce phénomène. Par contre, les mesures étaient entachées d'incertitudes importantes, dues à des techniques de mesure non appropriées à des phénomènes si rapides. L'objectif de ce travail a été de concevoir et mettre en place une expérience capable de simuler un RIA à petite échelle, pour mieux comprendre les caractéristiques de l'ébullition lorsque la paroi monte en température très rapidement. De plus, ce dispositif expérimental devait être apte à étudier des montées en température moins violentes pour améliorer la connaissance de l'ébullition transitoire en général. Cette expérience a été conçue à l'Institut de Mécanique des Fluides de Toulouse. Elle est constituée d'une feuille métallique d'acier de 50µm d'épaisseur, formée en demi cylindre (8mm de diamètre et 200mm de longueur) et chauffée par effet Joule. Elle est entourée par du fluide réfrigérant HFE7000, qui permet de travailler en similitude par rapport au cas réel en eau. Le fluide est confiné par un deuxième demi cylindre en verre, ayant 34mm de diamètre. Les expériences peuvent être en vase ou avec écoulement, écoulement qui a été caractérisé par des mesures PIV. Plusieurs débits peuvent donc être employés et le sous-refroidissement du liquide est aussi ajustable. L'emploi d'une alimentation pilotable et très flexible permet d'obtenir des chauffages du métal jusqu'à 2500K/s, mais aussi des montées en température plus faibles, pour tracer des courbes d'ébullition stationnaires ou faiblement transitoires. La température de la paroi est mesurée grâce à une caméra infrarouge, couplée à des visualisations rapides et à des mesures de pression et température dans le liquideBoiling phenomena can be found in the everyday life, thus a lot of studies are devoted to them, especially in steady state conditions. Transient boiling is less known but still interesting as it is involved in the nuclear safety prevention. In this context, the present work was supported by the French Institute of Nuclear Safety (IRSN). In fact, the IRSN wanted to clarify what happens during a Reactivity-initiated Accident (RIA). This accident occurs when the bars that control the nuclear reactions break down and a high power peak is passed from the nuclear fuel bar to the surrounding fluid. The temperature of the nuclear fuel bar wall increases and the fluid vaporises instantaneously. Previous studies on a fuel bar or on a metal tube heated by Joule effect were done in the past in order to understand the rapid boiling phenomena during a RIA. However, the measurements were not really accurate because the measurement techniques were not able to follow rapid phenomena. The main goal of this work was to create an experimental facility able to simulate the RIA boiling conditions but at small scale in order to better understand the boiling characteristics when the heated-wall temperature increases rapidly. Moreover, the experimental set-up was meant to be able to produce less-rapid transients as well, in order to give information on transient boiling in general. The facility was built at the Fluid-Mechanics Institute of Toulouse. The core consists of a metal half-cylinder heated by Joule effect, placed in a half-annulus section. The inner half cylinder is made of a 50 microns thick stainless steel foil. Its diameter is 8mm, and its length 200mm. The outer part is a 34mm internal diameter glass half cylinder. The semi-annular section is filled with a coolant, named HFE7000. The configuration allows to work in similarity conditions. The heated part can be place inside a loop in order to study the flow effect. The fluid temperature influence is taken into account as well. A flexible power supply that can generate a free-shape signal, allows to get to a wall-temperature increase rate up to 2500 K/s but also to obtain lower rates, which permits to study weaker transients and steady state conditions. The thermal measurements are realised by means of an infra-red camera and a high-speed camera is employed in order to see the boiling phenomena at the same time. From the voltage and current measurements the heat flux that is passed to the fluid is known
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Sun, Chih-Chen. "Modeling and characterization of potato quality by active thermography." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3012.
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Omer, Muhammad. "Impingement Cooling: Heat Transfer Measurement by Liquid Crystal Thermography." Thesis, Linköping University, Applied Thermodynamics and Fluid Mechanics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-52859.
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In modern gas turbines parts of combustion chamber and turbine section are under heavy heat load, for example, the rotor inlet temperature is far higher than the melting point of the rotor blade material. These high temperatures causes thermal stresses in the material, therefore it is very important to cool the components for safe operation and to achieve desired component life. But on the other hand the cooling reduces the turbine efficiency, for that reason it is vital to understand and optimize the cooling technique.
In this project Thermochromic Liquid Crystals (TLCs) are used to measure distribution of heat transfer coefficient over a scaled up combustor liner section. TLCs change their color with the variation of temperature in a particular temperature range. The color-temperature change relation of a TLC is sharp and precise; therefore TLCs are used to measure surface temperature by painting the TLC over a test surface. This method is called Liquid Crystal Thermography (LCT). LCT is getting popular in industry due to its high-resolution results, repeatability and ease of use.
Test model in present study consists of two plates, target plate and impingement plate. Cooling of the target plate is achieved by impingement of air coming through holes in the impingement plate. The downstream surface of the impingement plate is then cooled by cross flow and re-impingement of the coolant air.
Heat transfer on the target plate is not uniform; areas under the jet which are called stagnation points have high heat transfer as compare to the areas away from the center of jet. It is almost the same situation for the impingement plate but the location of stagnation point is different. A transient technique is used to measure this non-uniform heat transfer distribution. It is assumed that the plates are semi-infinitely thick and there is no lateral heat transfer in the plates. To fulfill the assumptions a calculated time limit is followed and the test plates are made of Plexiglas which has very low thermal conductivity.
The transient technique requires a step-change in the mainstream temperature of the test section. However, in practical a delayed increase in mainstream temperature is attained. This issue is dealt by applying Duhamel’s theorem on the step-change heat transfer equation. MATLAB is used to get the Hue data of the recorded video frames and calculate the time taken for each pixel to reach a predefined surface temperature. Having all temperatures and time values the heat transfer equation is iteratively solved to get the value of heat transfer coefficient of each and every pixel of the test surface.
In total fifteen tests are conducted with different Reynolds number and different jet-to-target plate distances. It is concluded that for both the target and impingement plates, a high Reynolds number provides better overall heat transfer and increase in jet-to-target distance
decreases the overall heat transfer.
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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.
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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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Niehof, Sjoerd Petrus. "Video thermography: complex regional pain syndrome in the picture." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2007. http://hdl.handle.net/1765/10704.
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Harik, Marc Anthony. "CHARACTERIZATION OF DEFECTS IN METAL SHEETS VIA INFRARED THERMOGRAPHY." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_theses/32.
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Defects in Aluminum, Stainless steel and galvanized steel sheets are studied in reflection mode infrared thermography. The effect of material properties, surface finish, heating intensity, heater emission spectra, pixel size and defect size are studied. Contrast is governed by heat quality, emissivity and defect geometry—which follows a logarithmic trend. The diameter detected via infrared thermography is found to be at least 30% larger than the measured diameter and sub-pixel defects can be detected. The use of gradient and Laplacian of temperature is introduced as a means of increasing defect contrast and mitigating heater variation.
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Hu, Ching Wen. "Fabric integrity evaluation of structural materials using infrared thermography." Thesis, University of South Wales, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395349.
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Yu, Jimmy Kalok. "Using infrared thermography to measure the maturity of concrete." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14321.
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Pierce, James. "Defect Detection in Additive Manufacturing Utilizing Long Pulse Thermography." Scholar Commons, 2018. http://scholarcommons.usf.edu/etd/7219.
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Additive Manufacturing (AM), over the years, has seen a tremendous amount of research for improving the manufacturability of materials into final products. The main advantages of additive manufacturing are the minimizing of waste material as it is an additive process. As well as the ability to create custom low-volume products without the need for creation of expensive tooling or programming before manufacturing begins. Because of these advantages, however, AM is susceptible to unique challenges in the quality side of manufacturing. These challenges include minimizing and detecting defects during the build. The focus of this research looks at the capability of using Pulse Thermography (PT), a nondestructive testing method, with longer than typical pulse length on additively manufactured parts for surface and sub-surface defect detection as well as thermal property determination based on a known void depth.
The first and second part of this research will look at a range of pulse lengths greater than 100ms to determine if the previously defined assumption is necessary for accurate defect detection. The significance of increasing the pulse length is to have the ability to increase the overall energy input into the part without having to increase the power. Allowing for the capability of defect detection for both shallow and deeper defects with the same overall setup. One-dimensional simulations r using Forward Time Center Space (FTCS) approximation, show that the assumption of an instantaneous pulse is relative, and defects can be accurately calculated within a range of pulse lengths. Based on the simulations, experimentation was conducted to determine the capability of calculating sub-surface defect depths with a longer pulse on a FDM printed ABS part with 100% in fill. The defect depths will range from 0.3mm to 1.8mm and the widths of the defects used for depth calculation will be 8x8mm. Results of the experiments show that even with FDM printed parts defect depths were accurately calculated up to a depth of 1.2mm.
The third aspect of this research looks at the infrared reflections emitting off the surface during the longer pulse. With a longer pulse length, there is more time for the infrared camera to collect thermograms of the surface during the pulse. It was noticed during sub-surface defect detection that the infrared reflections paint a picture of the surface characteristics of the part. Characteristics that include surface imperfections not intended in the original build parameters such as under extrusions and cracks. Defects as small as 150μm with a thermal pixel resolution 75μm are detected.
The third and final aspect of this research looks at the ability to use PT with a longer pulse to determine thermal properties of a binder jetted additively manufactured part as well as packing factors that may be otherwise be unknown. When a product is binder jetted a chemical binder is added to the powder layer by layer until a product is formed.
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Hedayati, Vahid Peyman. "Automatic defect detection and depth estimation using pulsed thermography." Master's thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/25638.
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L’évaluation non-destructive (END) est une branche de la science qui s’intéresse à l’uniformité, la qualité et la conformité des matériaux et les composants qu’ils servent à construire. Les techniques de END visent à repérer et à mesurer les caractéristiques principales des matériaux sans en affecter ou à en détruire la structure ou la fonctionnalité. L’END permet d’observer les propriétés internes des pièces et de détecter les défauts sous leur surface. Cette approche est devenue graduellement une technologie importante pour garantir la sécurité et la fiabilité de plusieurs composantes de système en design, en fabrication et en développement de produits. La thermographie infrarouge est une approche d’END sans contact rapide qui utilise des caméras thermiques. Elle permet de détecter l’énergie thermique émise par les objets et à en afficher la distribution en température de la surface du spécimen sous observation. Dans ce projet, notre objectif est d’exploiter la thermographie infrarouge pour détecter les défauts sous la surface des objets. Plus spécialement, nous nous intéressons à la localisation des défauts et à l’estimation de leur profondeur sous la surface. Le manuscrit présente une investigation de différentes méthodes de localisation de défauts et de mesure de leur profondeur des défauts sous la surface pour différentes catégories de matériaux.Non-Destructive Testing (NDT) is an aspect of science concerning on uniformity, quality and serviceability of materials and their components. NDT techniques attempt to inspect and measure significant features of materials without changing or destroying their structure or functionality. NDT makes it possible to observe the internal properties of parts and detect the undersurface defects. NDT has progressively become an important technology to assure safety and reliability of many system components in the design, manufacturing and development areas. Infrared thermography is essentially a fast non-contact NDT inspection method that uses thermographic cameras. This technique detects the infrared energy emitted from objects and displays the corresponding temperature distributions on the specimen. In this project, we aim to use infrared thermography for detecting subsurface defects. Localizing the defects and estimating their depths are the important problems to be addressed in our research project. The manuscript investigates different methods related to these challenges.
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Shrestha, Survesh Bahadur. "Defect Detection on Rail Base Area Using Infrared Thermography." OpenSIUC, 2020. https://opensiuc.lib.siu.edu/theses/2758.
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This research aims to investigate the application of infrared thermography (IRT) as a method of nondestructive evaluation (NDE) for the detection of defects in the rail base area. Rails have to withstand harsh conditions during their application. Therefore, defects can develop in the base area of rails due to stresses such as bending, shear, contact, and thermal stresses, fatigue, and corrosion. Such defects can cause catastrophic failures in the rails, ultimately leading to train derailments. Rail base defects due to fatigue and corrosion are difficult to detect and currently there are no reliable or practical non-destructive evaluation (NDE) methods for finding these types of defects in the revenue service. Transportation Technology Center, Inc. (TTCI) had previously conducted a research on the capability of flash IRT to detect defects in rail base area based on simulation approach. The research covered in this thesis is the continuation of the same project.In this research, three rail samples were prepared with each containing a notched-edge, side-drilled holes (SDHs), and bottom-drilled holes (BDHs). Two steel sample blocks containing BDHs and SDHs of different sizes and depths were also prepared. Preliminary IRT trials were conducted on the steel samples to obtain an optimal IRT setup configuration. The initial inspections for one of the steel samples were outsourced to Thermal Wave Imaging (TWI) where they employed Thermographic Signal Reconstruction (TSR) technique to enhance the resulting images. Additional inspections of the steel samples were performed in the Southern Illinois University-Carbondale (SIUC) facility. In case of the rail samples, the SDHs and the notched-edge reflectors could not be detected in any of the experimental trials performed in this research. In addition, two more rail samples containing BDHs were prepared to investigate the detection capabilities for three different surface conditions: painted, unpainted, and rusted. The painted surface provided a best-case scenario for inspections while the other conditions offered further insight on correlating the application to industry-like cases.A 1300 W halogen lamp was employed as the heat source for providing continuous thermal excitation for various durations. Post-processing and analysis of the resulting thermal images was performed within the acquisition software using built-in analysis tools such as temperature probes, Region of Interest (ROI) based intensity profiles, and smoothing filters. The minimum defect diameter to depth (aspect) ratio detected in preliminary trials for the steel sample blocks were 1.0 at a diameter of 4.7625 mm (0.1875 in) and 1.5 at a diameter of 3.175 mm (0.125 in). For the inspection of painted rail sample, the longest exposure times (10 sec) provided the best detection capabilities in all sets of trials. The three holes having aspect ratio greater or equal to 1.0 were indicated in the thermal response of the painted and rusted samples while only the two holes having aspect ratio greater or equal to 1.5 were indicated in the unaltered sample. Indications of reflectors were identified through qualitative graphical analysis of pixel intensity distributions obtained along a bending line profile. The results obtained from the painted sample provided a baseline for analyzing the results from the unpainted and rusted rail samples. This provided an insight on the limitations and requirements for future development. The primary takeaway is the need for an optimized heat source. Poor contrast in the resulting image for the unpainted and rusted rail samples is experienced due to both noise and lack of penetration of the heat energy. This could have been due to decreased emissivity values. Moreover, the excitation method employed in this research does not comply with current industry standards for track clearances. Therefore, exploration of alternative excitation methods is recommended.
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Bangalore, Gurudutt S. "Nondestructive evaluation of FRP composite members using infrared thermography." Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2419.
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Thesis (M.S.)--West Virginia University, 2002.Title from document title page. Document formatted into pages; contains viii, 101 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 98-101).
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Vidas, Stephen G. "Handheld 3D thermography using range sensing and computer vision." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/68030/1/Stephen_Vidas_Thesis.pdf.
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This thesis developed a method for real-time and handheld 3D temperature mapping using a combination of off-the-shelf devices and efficient computer algorithms. It contributes a new sensing and data processing framework to the science of 3D thermography, unlocking its potential for application areas such as building energy auditing and industrial monitoring.
New techniques for the precise calibration of multi-sensor configurations were developed, along with several algorithms that ensure both accurate and comprehensive surface temperature estimates can be made for rich 3D models as they are generated by a non-expert user.
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Rauf, Abdul. "Thermal reconstruction techniques for the inspection of laminated composites." Thesis, University of Strathclyde, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291991.
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Estrada, Catalina. "Infrared Thermography to Evaluate Guastavino Vaulting at the West Side Market." Kent State University Honors College / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1368186834.
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Kang, Jihun. "Quantifying cognitive workload and defining training time requirements using thermography." Diss., Mississippi State : Mississippi State University, 2008. http://library.msstate.edu/etd/show.asp?etd=etd-10132008-113238.
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Fike, Gregory Michael. "Using Infrared Thermography to Image the Drying of Polymer Surfaces." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4808.
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During the drying of a surface, the liquid evaporation acts to keep the temperature relatively constant, due to evaporative cooling. As the drying nears completion the liquid film begins to break, exposing areas that are no longer cooled through evaporation, which begin to heat. Although this heating can be measured with an Infrared (IR) camera, the sensitivity is often not sufficient to recognize the point at which the film breaks. Complicating the measurement is the changing emissivity that commonly occurs as objects dry.
The sensitivity and emissivity issues can be addressed by analyzing the temperature in the area of interest and computing the coefficient of variance (COV) of the temperature. This technique is compared to temperature and standard deviation measurements made with an IR camera and the COV technique is shown to be superior for determining when the liquid film breaks. The film breakage point is found to vary with temperature and material roughness in two industrially significant applications: the drying of wood flakes and the drying of polymer films.
Film breakage in wood flakes is related to detrimental finished quality problems and also to emission problems. The rate at which an adhesive dries affects the roughness of the polymer film and subsequently, the bond strength. The COV technique is used to predict the roughness of the finished polymer film. Use of the COV technique allows the drying of a liquid film to be visualized in a way that has been previously unreported.
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Berglind, Henrik Oförstörande provning. "Nondestructive detection of glue deficiency in laminated wood using thermography /." Luleå, 2003. http://epubl.luth.se/1402-1544/2003/02.
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Poey, S. M. "Infrared thermography of the anterior eye during contact lens wear." Thesis, University of Manchester, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494480.
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Grimler, Henrik. "Investigating Urea Vaporization in a Controlled Environment Using Infrared Thermography." Thesis, KTH, Skolan för kemivetenskap (CHE), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-174360.
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As the emission legislation becomes more stringent, higher demands are put on the aftertreatment system in trucks. For dealing with nitrous oxides, AdBlue® (urea–water solution) is injected into the exhausts which evaporates and reduces nitrous oxides to nitrogen. At low exhaust temperatures, it is more difficult to evaporate the injected AdBlue® as the exhausts contain less energy. The injected solution may instead form a wall film. In this wall film, side reactions can occur which leads to the formation of deposits. This thesis aims at understanding how and when wall films and deposits are formed. To achieve this, a test rig that allowed visual and infrared observations of the process and variation of governing properties was designed and built. The results show that thicker plates can sustain higher dosages than thinner plates since the temperature drop and film area are smaller for the thicker plate. It was also observed that at plate temperatures >340 °C, the water in the impacting spray evaporated, leaving a urea dust in the gas phase. It is also clear that deposits form faster at higher gas temperatures (> 350 °C) compared to at lower temperatures (200–250 °C). The deposits form at the edge of the wall film in a region with a temperature higher than in the middle of the wall film. At lower temperatures, a wall film that spreads out over a very large area is formed and after a longer time period, deposits form at obstacles and at the wall film edge. Experiments for 2 h at lower temperatures left approximately the same amount of deposits as experiments for 30 min at higher temperatures.När lagkraven blir strängare sätts högre krav på efterbehandlingssystemet i lastbilar. För att få bort nitrösa gaser injiceras AdBlue® (urea–vattenlösning) in i avgaserna vilken förångas och reducerar de nitrösa gaserna till ofarligt kväve. Vid låga avgastemperaturer är det svårare att förånga den injicerade AdBlue®–lösningen då avgaserna innehåller mindre energi. Den injicerade lösningen kan istället bilda en väggfilm. I denna väggfilm kan sidoreaktioner ske vilket leder till bildning av utfällningar. Detta examensarbete syftar till att öka förståelsen för hur och när väggfilmer och utfällningar bildas. För att uppnå detta designades och byggdes en testrigg i vilken visuella och infraröda observationer kan göras och influerande parametrar varieras. Resultaten visar att tjockare plåtar kan utstå högre doseringar jämfört med tunnare plåtar, eftersom lägre temperaturminskning och film area uppmätts för den tjockare plåten. Det sågs också att vid plåttemperaturer >340 °C så förångades vattnet i AdBlue®-lösningen först och efterlämnade ett ureadamm i gasfasen. Det konstaterades också att utfällningar bildas snabbare vid högre gastemperaturer (> 350 °C) jämfört med vid lägre temperaturer (200–250 °C). Utfällningarna bildas vid kanten av väggfilmen i en region som har en temperatur som är högre än den i mitten av väggfilmen. Vid lägre temperaturer bildas en väggfilm som sprider ut sig över en stor area och med tiden bildas utfällningar vid hinder och vid filmkanten. Experiment under 2 h vid låg gastemperatur gav jämförbara mängder utfällningar som experiment under 30 min vid högre temperatur.
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Susa, Mirela. "Numerical Modeling of Pulse Thermography Experiments for Defect Characterisation Purposes." Thesis, Université Laval, 2009. http://www.theses.ulaval.ca/2009/26251/26251.pdf.
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Bharara, Manish. "Liquid crystal thermography in neuropathic assessment of the diabetic foot." Thesis, Bournemouth University, 2007. http://eprints.bournemouth.ac.uk/10470/.
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Primary aetiologic factors of diabetic foot disease include peripheral neuropathy and peripheral vascular disease. Assessment of circulation, neuropathy, and foot pressure is employed routinely to determine the risk of foot ulceration in the patient with diabetes mellitus. Routine neuropathic evaluation includes assessment of sensory loss in the plantar skin of the foot using both the Semmes Weinstein monofilament and the biothesiometer. Progressive degeneration of sensory nerve pathways is thought to affect thermoreceptors and mechanoreceptors. However, thermological measurements of the foot to assess responses to thermal stimuli and cutaneous thermal discrimination threshold are relatively uncommon. Recent improvements in liquid crystal technology (LCT) including insensitivity to pressure, faster response times, lower cost and fast image acquisition offer potential for routine thermographic assessment of the diabetic foot. The present study was designed to evaluate if an association exists between abnormal plantar thermal images and sensory loss under conditions of normal loading. The system comprises a robust measurement platform, thermochromic liquid crystal polyester sheet (TLC), instrumentation and analysis software. In vitro calibration was performed to characterise three physical forms of TLC on the basis of linearity, hysteresis, pressure sensitivity and response time. An in vivo pilot evaluation study of the system was performed using three sub-groups (i) neuropathic diabetic (n=30), (ii) non neuropathic diabetic (n=30) and (iii) a healthy control group (n=30). The principal results of this study indicate raised plantar temperatures for the diabetic groups at baseline and post stress relative to the control group. Furthermore, poor recovery response to thermal stimulus in the neuropathic diabetic group suggests degeneration of thermoreceptors. Thus by assessing the thermal parameters at the same sites as that of sensory testing, the new LCT based approach appears capable of providing an alternative confirmation of clinical neuropathy and offers potential as an improved method compared to existing techniques.
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Jama, Bandile, Jasson Gryzagoridis, and Graham Wilson. "Aspects of thermography for non-destructive testing in mechanical maintenance." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2579.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2017.Infrared thermography (IRT) is a non-contacting, non-destructive testing (NDT) technique that provides relatively fast results from inspections; for example, in the detection of defects in engineering components and in systems' condition monitoring. This study examines the use and possible effectiveness of infrared thermography for the detection of faults and defects in just a few aspects that one encounters in the vast mechanical maintenance arena. The study discusses three aspects of infrared thermography, namely internal leaks inspections using passive infrared thermography, pulse thermography and induction thermography both active IRT NDT techniques for the detection of subsurface and surface defects. The promising results that were obtained by performing an experiment in the laboratory using a model fluid handling pipe network, with three isolation valves connected in parallel, encouraged performing inspections in an operating power plant, where it was suspected that there were leaks from safety and drain isolation valves. In both situations, the results were obtained in a short period of time and indicated that passive infrared thermography can detect internal leaks in pipe networks. Pulsed thermography is an active non-contacting non-destructive testing technique used to detect subsurface defects in monolithic materials and delamination's in composites. In the particular experiment that was performed pulse thermography was benchmarked with the conventional technique of ultrasound testing. PVC, stainless steel and mild steel specimens manufactured with flat bottom holes (as models of subsurface defects) were subjected to pulse thermography. The time duration to detect the presence of a defect represented by a temperature contrast or a hot spot on the specimen's surface was approximately a couple of seconds following the thermal excitation. No further characterization of the defect was possible with the technique. In contrast when using the ultrasound testing technique to test the specimens, it took considerable time to detect the defects, however, data in terms of size and depth beneath the surface became available thus enabling their full characterization.
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Roberts, Matthew Thomas. "Induction Infrared Thermography for Non-Destructive Evaluation of Alloy Sensitization." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/90668.
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The sensitization of stainless steel describes the process by which a high-carbon steel alloy is heated above a certain threshold (either naturally or artificially) followed by a cooling period during which chromium (one of the elements most responsible for providing stainless steel with its corrosion-inhibiting properties) forms new compounds with the carbon present in the steel. With the chromium being taken from the parent material to form these compounds, the corrosion-resistant properties are compromised, which can lead to corrosion, cracking, and broader failure. Currently, the accepted techniques used to test for the presence of sensitization are qualitative and/or destructive in nature. Attempts have been made to non-destructively detect and characterize sensitization through various means, but all with mixed results. With the use of these high-carbon alloys in a range of industries, a comprehensive, in-place process is desirable.
This thesis will focus specifically on non-destructive evaluation of sensitization seen as a result of welding steel plates using induction infrared thermography (IIRT). This process uses an induction coil to generate heat within a sample whose resulting heat signature can then be detected with an infrared (IR) camera and analyzed. Previous IIRT experimental results have shown higher levels of heating in the HAZ when sensitization is present as it modifies the original microstructure of the material. New IIRT experiments have been conducted on both welded and unwelded 440C alloy samples to establish quantitative data on the heating profiles. These results (in conjunction with the appropriate experimental parameters) were then used to create a numerical model to replicate them. Despite some limitations in populating the model with accurate parameters, the results obtained were in good agreement with the experiments and provide a foundation for future work. Future work will focus on establishing a predictive tool that can detect and quantify the level of sensitization in an arbitrary steel sample in the field.Master of Science
The sensitization of stainless steel describes the process by which a high-carbon steel alloy is heated above a certain threshold (either naturally or artificially) followed by a cooling period during which chromium (one of the elements most responsible for providing stainless steel with its corrosion-inhibiting properties) forms new compounds with the carbon present in the steel. With the chromium being taken from the parent material to form these compounds, the corrosion-resistant properties are compromised, which can lead to corrosion, cracking, and broader failure. Currently, the accepted techniques used to test for the presence of sensitization are qualitative and/or destructive in nature. Attempts have been made to non-destructively detect and characterize sensitization through various means, but all with mixed results. With the use of these high-carbon alloys in a range of industries, a comprehensive, in-place process is desirable. This thesis will focus specifically on non-destructive evaluation of sensitization seen as a result of welding steel plates using induction infrared thermography (IIRT). This process uses an induction coil to generate heat within a sample whose resulting heat signature can then be detected with an infrared (IR) camera and analyzed. Previous IIRT experimental results have shown higher levels of heating in the HAZ when sensitization is present as it modifies the original microstructure of the material. New IIRT experiments have been conducted on both welded and unwelded 440C alloy samples to establish quantitative data on the heating profiles. These results (in conjunction with the appropriate experimental parameters) were then used to create a numerical model to replicate them. Despite some limitations in populating the model with accurate parameters, the results obtained were in good agreement with the experiments and provide a foundation for future work. Future work will focus on establishing a predictive tool that can detect and quantify the level of sensitization in an arbitrary steel sample in the field.
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Miceli, Marybeth. "Assessment of Infrared Thermography for NDE of FRP Bridge Decks." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/36320.
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Statistics released in the fall 1989 showed that 238,357 (41%) of the nation's 577,710 bridges are either structurally deficient or functionally obsolete. New materials, such as fiber reinforced polymeric composites (FRP), are being suggested for use in bridge systems to solve some of the current problems. These materials are thought to be less affected by corrosive environmental conditions than conventional civil engineering materials. Therefore they may require less maintenance and provide longer life spans. More specifically, glass fiber reinforced vinyl ester matrix composites are considered possible replacements for deteriorating conventional bridge decks due to their durability, decreased weight, and relative affordability.
In order to facilitate rapid acceptance of FRP structural components into the world of civil structural engineering, effective and efficient NDE techniques must be explored and documented in these situations.
This thesis will discuss the use of Infrared Thermography (IRT) as a means of detecting debonds and voids caused by conditions encountered both in fabrication and in the field. As forced convective hot air is applied within the bridge deck, debonds between bridge deck components near the riding surface appear cold while imperfections near the bottom of the deck give rise to concentrations of heat. These variations in thermal propagation patterns are observed by the infrared camera and indicate possible structural deficiencies.
Results of experimentation and thermal analyses from laboratory studies of a model bridge deck and some from in situ full-scale investigations are presented.Master of Science
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Agarwal, Kevin. "Infrared Thermography for In-pile Imaging of Nuclear Fuel Cracking." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555343437656063.
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Sargent, Gerald R. "The use of thermography in clinical Thoracolumbar disease in Dachshunds." Thesis, Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/1059.
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Zhang, Ying. "Thermal diffusivity evaluation for carbon-carbon composites using infrared thermography /." Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1456294291&sid=1&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Thesis (Ph. D.)--Southern Illinois University Carbondale, 2007."Department of Mechanical Engineering and Energy Processes." Includes bibliographical references (leaves 95-102). Also available online.
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Bainbridge, Bradley Glenn. "OPTIMIZATION OF TRANSIENT THERMOGRAPHY INSPECTION OF CARBON FIBER REINFORED PLASTICS." OpenSIUC, 2010. https://opensiuc.lib.siu.edu/theses/300.
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Infrared thermography was used to evaluate Carbon Fiber Reinforced Panels (CFRP) and optimize the inspection process so that a set of guidelines can be established in order to be efficient and effective. It has been shown in previous work that when a material is heated up the heat will diffuse through the material at a constant rate. However, if there is a defect in the material, such as a delamination, this defect will act like an insulator. When this happens the heat cannot penetrate as quickly as the rest of the material so the surface above the defect shows up hotter than the rest of the material. An operator looks for inconsistent temperatures in the sample to determine the quality of the piece. Samples with simulated defects were made and modeled using a finite element program. Heat will be applied to the models and the temperature profiles analyzed. Along with changing the heat and time, different post-processing techniques were used to improve the method in determining defects in the sample. Once this has been optimized, actual CFRP with the same simulated defects was experimentally tested using the conditions from the analytical model. The analytical and experimental data was compared to insure that the testing process has been optimized. A standardized process was developed for evaluating the CFRPs using infrared thermography.