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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
361

Entwicklung einer Temperaturmessmethodik für die aktive Strahlerleistungs- und Strahlerabstandsregelung beim Infrarotschweißen von Kunststoffen

Constantinou, Marios, Gehde, Michael, Fuhrich, René, Schüle, Eduard, Mittler, Christian 07 December 2017 (has links) (PDF)
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.
362

Caractérisation de l'endommagement des composites à matrice polymère par une approche multi-technique non destructive

Harizi, Walid 11 December 2012 (has links)
Cette étude novatrice consiste à mettre en oeuvre dans un même protocole expérimental, trois techniques de caractérisation non destructive en simultané : l’émission acoustique, la thermographie infrarouge et les ultrasons pour la caractérisation de l’endommagement des matériaux Composites à fibres continues et à Matrice Polymère (CMP) à plis croisés [0/90]S. Chaque technique a permis demontrer sa potentialité à révéler l’endommagement dépendant de ses spécificités intrinsèques. L'émission acoustique a été utilisée sous sa forme classique et couplée avec une classification de données obtenue par les k-means et la carte de Kohonen. La thermographie infrarouge a été étudiée selon ses deux formes passive et active, les méthodes ultrasonores ont été exploitées en termes d’amplitude et de vitesse des ondes longitudinales et des ondes de Lamb respectivement. Il a été montré que l’approche multitechnique adoptée dans ce travail est très intéressante pour obtenir un diagnostic complet sur l’état de santé du matériau au repos et sous différents niveaux de chargement mécanique en traction. Il s’est avéré aussi que l’aspect « complémentarité » entre les trois techniques était plus envisageable que celui de la « redondance ». La fusion des données a été utilisée pour avoir une prise de décision fiable, complète et plus crédible sur les différents mécanismes d’endommagement susceptibles d’apparaître dans un matériau CMP. Ceci n’a été possible que pour les deux techniques d’imagerie, le C-scan ultrasonore et la thermographie infrarouge. En conclusion, les résultats montrent que ces trois techniques sont potentiellement capables de qualifier l’état d’endommagement du matériau, mais qu’elles ne le quantifient pas de la même manière / This innovative study consists to implement in the same experimental procedure three non destructive techniques simultaneously: acoustic emission, infrared thermography and ultrasonic waves for the characterization of damage in cross ply Polymer Composite Materials (PCM) [0/90]S. Each technique has demonstrated its potential to reveal the damage that depends on its intrinsic characteristics. Acoustic emission has been used in its classical form and coupled with a data classification obtained by k-means and Kohonen map. Infrared thermography has been studied using both passive and active forms, ultrasonic methods have been used by exploiting amplitude and velocity of longitudinal and Lamb waves respectively. It has been shown that the adopted multi-technique approach is veryinteresting to obtain a full diagnostic of the health state of the material before and after uniaxial mechanical loading. The “complementarity” aspect between the three used techniques is showed more interesting that “redundancy” aspect. The data fusion theory was used to have a reliable, comprehensive and credible decision about the different damage mechanisms may appear in PCM material. This has been possible only for the two imaging techniques, ultrasonic C-scan and infrared thermography. All in all, the results show that these three techniques are potentially able to describe the damage state of the material, but they don’t quantify it with the same manner
363

Méthode d’hétérodynage pour la caractérisation de propriétés thermophysiques par thermographie infrarouge dans une large gamme spatiale et temporelle

Clerjaud, Lilian 23 June 2010 (has links)
De nos jours, l’apport de la miniaturisation a permis d’innombrables progrès scientifiques et techniques : de la microélectronique à la microfluidique et dernièrement les nanotechnologies. Autant de domaines où les enjeux économiques de suivi de qualité ou d’optimisation de production peuvent nécessiter une étape de caractérisation des propriétés intrinsèques des constituants. Parmi ces propriétés, les données thermophysiques permettent notamment de définir la capacité à stocker ou diffuser la chaleur (conductivité, effusivité ou conductivité thermique par exemple). Une manière d’estimer ces propriétés passe par la connaissance du champ de température. Aux échelles microscopiques, seules des mesures de températures sans contact sont plus adaptées. Les travaux de cette thèse rentrent dans cette catégorie en présentant une méthode de caractérisation de propriétés thermophysiques aux échelles microscopiques par le biais de la thermographie infrarouge. En prenant exemple sur les méthodes hétérodynes développées pour la thermoréflectance, nous avons mis au point un stroboscope électronique dédiée à la thermographie infrarouge et permettant de suivre des excitations thermiques locales et périodiques de fréquences caractéristiques de l’ordre du kilohertz avec fréquence d’acquisition caméra de 25 Hz. En couplant cette méthode, que nous qualifierons de méthode d’Hétérodynage, avec une observation microscopique nous pouvons ainsi observer des phénomènes de diffusion longitudinale localisée à la surface d’échantillons diffusifs tels que les métaux et impossible à obtenir avec les applications standard de thermographie infrarouge. A partir de ces données expérimentales, nous montrons sur deux échantillons la manière de remonter à des valeurs de diffusivité dans le plan et dans l'épaisseur. De ces résultats, nous discuterons sur les limitations des estimations notamment dues à l'effet filtre passe bas du temps d'intégration de la caméra prépondérant lorsque l'excitation devient haute fréquence ou à la présence d'une couche émissive (dépôt de spray de peinture noire pour augmenter le contraste thermique) qui peut empêcher la propagation des ondes thermiques de la source au sein du matériau à caractériser dés que la fréquence d'excitation dépasse un seuil dépendant des propriétés thermiques du bicouche étudié. D'une autre manière, nous montrerons que des estimations de diffusivité thermique dans le plan ou transverse peuvent également être possible par une méthode d'hétérodynage en flash périodique. A titre d'applications futures, nous présenterons une première approche académique de modèle de diffusion avec transport sur un disque tournant pour des futures applications d'écoulement en goutes pour la microfluidique, une extension des estimations de diffusivité dans le plan pour obtenir des cartographies en scannant la zone étudiée et des résultats d'hétérodynage en régime périodique transitoire qui pourraient s'assimiler à une réponse de température en échelon. / Nowadays, the contribution of the miniaturization has led to countless advances in science and technology: microelectronics, microfluidics, nanotechnologies... All areas where the economics of quality monitoring and the optimization of production may require a step of characterizing the intrinsic properties of these constituents. Among these porperties, the thermophysical datas can defined the ability to store or distribute the heat (thermal conductivity, effusivity, diffusivity for example). A way to estimate these properties needs the knowledge of the temperature field. At microscale, the measurement temperature without contact is well adapted. The work of this thesis fall into this category by offering a method to characterize the thermophysical properties at microscopic scales by means of infrared thermography. With the help of the heterodyne methods developed for the Thermoreflectance, an electronic stroboscope has been developped. This method is dedied to the infrared thermography and allowing to follow thermal local and periodical excitations with a characteristic frequency around with a frame camera frequency of . By coupling this heterodyne method with microscope lens, it is possible to observe thermal diffusion phenomena longitudinal and transverse localized to the surface of the diffusive sample like metals and impossible to obtain with standard infrared thermography. From experimental data, the values of in-plane or transverse thermal diffusivity are obtained on two samples. Depending of these results, a debate is organized about the limitation of these estimations as the lowpass filter effect of the intregation time of the infrared camera which becomes important with high frequency excitation or the presence of an emissive of thin layer on the surface of the sample (dark spray coating for enhancing the thermal contrast) which can stopped the thermal waves propagation into the layer sample to characterize soon as the excitation frequency exceeds a threshold dependent on the thermal properties of the sample studied. In another way, the estimation of thermal in-plane or transverse diffusivity with an heterodyne method with repeated flash is shown in first results. For future applications, a first academic approach of thermal diffusion model with transport on rotating disk, an extension of the thermal in-plane diffusivity estimation to obtain cartography by scanning the sample area and few heterodyne results in transient periodic regime which are assilimated to a response level were shown.
364

Etudes sur le diagnostic des systèmes par thermographie infrarouge / Research concerning the systems analyze by infrared thermography

Dragan, Razvan Gabriel 05 December 2014 (has links)
La thèse intitulée Études sur le diagnostic des systèmes par thermographie infrarouge propose des recherche théoriques et expérimentales dans un domaine complexe - le domaine des méthodes d’analyse non-destructive, spécialement la thermographie infrarouge utilisant des diverses sources d’excitation thermique: laser à CO2, lampes photographiques à halogène, sources électriques, micro-ondes et induction électromagnétique. L’analyse par thermographie infrarouge a été appliquée sur des divers systèmes soit du génie civil, soit de l’ingénierie médicale, dans le but de détecter des défauts internes et de surface, micro-fissures, des métaux inglobés, et, en même temps, l’analyse de leur influences dans le processus de transfert thermique. La thèse est structurée en six chapitres dont trois s’occupent de l’introduction, les objectifs de la recherche, les conclusions, les contributions originales et la valorisation des résultats (publies et contrats de recherches), ainsi que le développement futur du sujet de la thèse. Les trois chapitre suivants développent le sujet de la thèse en commençant avec une analyse rigoureuse de la littérature suivie par des études théoriques et expérimentaux sur l’analyse des systèmes par thermographie infrarouge : Le travail contient 181 figures et 12 tableaux à travers lesquels sont mis en évidence les résultats et des informations de haut niveau scientifique. Pendant le stage doctoral ont été réalisées et publies 10 articles dans les volumes des conférences internationales dont pour six le docteur est premier auteur. / The thesis “Research concerning the systems analyze by infrared thermography” proposestheoretical and experimental researches în the very complex domain of non destructiveinspection methods, especially the infrared thermography – CO2 laser excitation, halogen lamps,electric heat sources, microwaves and electromagnetic induction. The thermographic analyzewas applied on materials used în constructions and biomedical engineering, the goal being theinternal and external defect detection, micro cracks, the detection of the embed metallic materialsand also the analysis of their thermal influence in the heat transfer process. The thesis isstructured in six chapters and, among them: three are concerned on introduction, thesisobjectives, conclusions, original contribution and thesis valorization (published papers andresearch grants)/future research directions. The next three develop, consistently, the thesissubject, beginning with critical analyze of the specialized literature that is followed bytheoretical study, and the experimental study of systems by infrared thermography. The PhDthesis contains 181 figures and 12 tables în which are illustrated and highlighted results andinformation with a high scientific degree. During the research program, the author elaborated andpublished 10 papers in the proceedings of different scientific events in Romania and abroad, insix of them being the first author.
365

Efeito da água magnetizada sobre os parâmetros reprodutivos, zootécnicos e temperatura corporal em (Bos taurus indicus) / Effect of Magnetized Water on Reproductive, Zootechnic and Body Temperature Materials (Bos Taurus Indicus)

ANDRADE, I. B. 17 March 2017 (has links)
Submitted by Adriana Martinez (amartinez@unoeste.br) on 2017-06-01T14:42:01Z No. of bitstreams: 1 Isamara.pdf: 1900151 bytes, checksum: bf2306ee5b36c025c99dadb0b3ed1c84 (MD5) / Made available in DSpace on 2017-06-01T14:42:01Z (GMT). No. of bitstreams: 1 Isamara.pdf: 1900151 bytes, checksum: bf2306ee5b36c025c99dadb0b3ed1c84 (MD5) Previous issue date: 2017-03-17 / The objective of this study was to study the influence of magnetized water intake on body weight gain, body morphometry and reproductive system, semen characteristics and body and scrotal area temperatures with digital infrared thermography in young Nellore bulls in extensive management and In confinement. Twenty bulls with initial age of 14 months were used, divided into two groups: Treated - water ingestion treated by magnetic field; And Control - drinking water intake. Four collections were made, 2 in extensive management (14 and 18 months of age) and 2 in confinement (20 and 21 months of age), in which they were measured: climatic factors, rectal temperature, body weight, wither height, Length, width and height of the testicles, semen collection and infrared digital thermography of the eyeball, mufla, flank, ischium and scrotum. It was concluded that the intake of water treated by magnetic field was not efficient in relation to weight gain in pasture and in confinement, as well as for body morphometry and reproductive system. In confinement, there was also no influence of water treated by magnetic field on the quantitative and qualitative characteristics of the semen. Digital infrared thermography proved to be effective for measuring body and scrotal areas, where the grazing group treated with magnetic field water showed higher temperatures for the ocular globe, mufla, flank and ischium. For the scrotal pouch, the pasture, the temperature of the spermatic cord and testis were higher in the treated group; And in confinement, the temperature of the testes and tail of the epididymis were higher in the group with drinking water intake. / Objetivou-se estudar a influência da ingestão da água magnetizada no ganho de peso corpóreo, morfometria corpórea e do aparelho reprodutor, características do sêmen e temperaturas de áreas do corpo e escroto com termografia digital de infravermelho em touros jovens da raça Nelore em manejo extensivo e em confinamento. Foram utilizados 20 touros com idade inicial de 14 meses, divididos em dois grupos: Tratado - ingestão de água tratada por campo magnético; e Controle - ingestão de água potável. Foram realizadas 4 coletas sendo 2 em manejo extensivo (14 e 18 meses de idade) e 2 em confinamento (20 e 21 meses de idade), nas quais foram aferidos: fatores climáticos, temperatura retal, peso corpóreo, altura de cernelha, mensuração do comprimento, largura e altura dos testículos, colheita de sêmen e termografia digital por infravermelho do globo ocular, mufla, flanco, ísquio e escroto. Conclui-se que a ingestão da água tratada por campo magnético não se apresentou eficiente em relação ao ganho de peso a pasto e em confinamento, assim como para morfometria corpórea e do aparelho reprodutor. Em confinamento, também não houve influência da água tratada por campo magnético sobre as características quantitativas e qualitativas do sêmen. A termografia digital por infravermelho se mostrou eficaz para mensuração das áreas do corpo e da bolsa escrotal, onde a pasto o grupo com ingestão de água tratada por campo magnético apresentou temperaturas superiores para globo ocular, mufla, flanco e ísquios. Para bolsa escrotal, a pasto, a temperatura do cordão espermático e testículo foram superiores no grupo tratado; e em confinamento, a temperatura do testículo e cauda dos epidídimos foram superiores no grupo com ingestão de água potável.
366

Os efeitos da terapia manual aplicada na região cervical e torácica sobre a temperatura de músculos mastigatórios e sobre os sinais e sintomas de disfunção temporomandibular: estudo clínico, randomizado, placebo-controlado / The effects of manual therapy applied to the cervical and thoracic region on the temperature of the masticatory muscles and on the signs and symptoms of temporomandibular dysfunction: randomized clinical trial, placebo controlled

El Hage, Yasmin 12 December 2016 (has links)
Submitted by Nadir Basilio (nadirsb@uninove.br) on 2018-07-16T21:50:43Z No. of bitstreams: 1 Yasmin El Hage.pdf: 1970287 bytes, checksum: a115ee670601d955883a00022faa7af9 (MD5) / Made available in DSpace on 2018-07-16T21:50:43Z (GMT). No. of bitstreams: 1 Yasmin El Hage.pdf: 1970287 bytes, checksum: a115ee670601d955883a00022faa7af9 (MD5) Previous issue date: 2016-12-12 / Introduction: Temporomandibular dysfunction (TMD) is a complex multifactorial dysfunction commonly associated with other conditions such as cervical spine disorders. Although there is evidence of the correlation between a TMD and neck dysfunctions, treatment approaches address local and direct. Since TMD etiology is multidimensional, the present study hypothetize that a cervical and thoracic approach could reduce the signs and symptoms of TMD. Purpose: To evaluate the effects of a manual therapy protocol applied to the cervical and thoracic region on the signs and symptoms of TMD, as well as the temperature of the temporomandibular joint (TMJ), masticatory and cervical muscles. Methods: 30 subjects with a diagnosis of TMD according to RDC/TMD classified as severe or moderate, according to the Fonseca’s Anamnestic Index (FAI) were randomized into two groups: experimental (miofacial release and joint mobilization) and placebo ultrassound. The interventions were performed twice a week, 8 sessions total. Volunteers were assessed for TMD severity by FAI; Pain in TMJ and masticatory muscles, using a Numerical Pain Scale (END); Mandibular range of motion (ROM), through pachymetry; Level of pain and craniofacial dysfunction, according to the Craniofacial Pain and Dysfunction Index (CF-IDD); Cervical dysfunction level, according to Neck Disorders Index (NDI); Regarding the surface temperature of the TMJ and the anterior temporal muscles, masseter and upper trapezius, under pre and post intervention conditions, and under a 30 days follow-up. The study was approved by the Ethics and Research Committee of Universidade Nove de Julho and is registered in Clinical Trials under the number NCT02822469.Statistical analysis: Data distribution was normal. ANOVA was performed followed by Tukey's multiple comparison for group versus time interaction. The category changes between the moments and the groups were analyzed following a contingency table using the proportional comparison test for each category. The level of significance of 5% was considered. Results: Of the 186 volunteers screened, only 28 complete the study. No statistically significant difference was found between groups for any of the variables studied. Conclusion: The proposed treatment protocol applied to the thoracic and cervical region did not alter pain, ROM, TMD severity, cervical dysfunction level and superficial temperature of the TMJ and the masseter, anterior temporal and upper trapezius muscles in patients with severe and/or moderate TMD. / Introdução: Disfunção temporomandibular (DTM) é uma disfunção complexa e multifatorial comumente associada à outras condições como desordens da coluna cervical. Apesar de haver evidências da correlação entre a DTM e disfunções cervicais, as propostas de tratamento incluem abordagem local e direta. Uma vez que a etiologia da DTM é multidimensional, o presente estudo hipotetiza que uma abordagem cervical e torácica poderia reduzir os sinais e sintomas de DTM. Objetivo: Avaliar os efeitos de um protocolo de terapia manual aplicado sobre a região cervical e torácica sobre os sinais e sintomas da DTM, bem como sobre a temperatura da articulação temporomandibular (ATM), músculos mastigatórios e cervicais. Metodologia: 30 sujeitos com diagnóstico de DTM conforme o RDC/TMD, classificada como grave ou moderada, de acordo com o Índice Anamnésico de Fonseca (IAF) foram randomizados em 2 grupos: experimental (liberação miofascial e mobilização articular) e ultrassom placebo. As intervenções foram aplicadas 2 vezes por semana, totalizando 8 sessões. Os sujeitos foram avaliados quanto à gravidade da DTM, pelo IAF; dor na ATM e nos músculos mastigatórios, utilizando a escala numérica de dor (END); amplitude de movimento mandibular (ADM), por meio da paquimetria; nível de dor e disfunção craniofacial, de acordo com o Índice de Dor e Disfunção Craniofacial (IDD-CF); nível de disfunção do cervical, conforme o Índice de Disfunção Cervical (NDI); e quanto a temperatura da superfície da ATM e dos músculos temporal anterior, masseter e trapézio superior, nas condições pré intervenção, pós intervenção e follow-up após 30 dias do término do protocolo. O estudo foi aprovado pelo comitê de ética e cadastrado no clinical trials sob o número NCT02822469. Análise estatística: Os dados apresentaram distribuição normal e foram analisados utilizando a ANOVA seguido de comparação múltipla de Tukey para a interação grupo versus momento. As mudanças de categorias entre os momentos e os grupos foram analisadas seguindo uma tabela de contingência por meio do teste de comparação de proporções para cada categoria. Considerou-se o nível de significância de 5%. Resultados: Dos 186 voluntários triados, apenas 28 completaram o estudo. Não foi encontrada diferença estatisticamente significante entre os grupos para nenhuma das variáveis estudadas. Conclusão: O protocolo de tratamento proposto, aplicado sobre a região torácica e cervical não alterou a dor, ADM, gravidade da DTM, nível de disfunção cervical e temperatura superficial da ATM e dos músculos masseter, temporal anterior e trapézio superior em pacientes com DTM grave e moderada.
367

Thermométries ultrasonore et infrarouge pour le contrôle de la protection myocardique / Ultrasonic and infrared thermometries for the control of myocardial protection

Engrand, Céline H. 30 November 2016 (has links)
Le succès de la chirurgie cardiaque dépend essentiellement de la préservation des tissus durant l'opération. Afin d'optimiser cette dernière, une protection myocardique est appliquée à travers la perfusion d'une cardioplégie hypothermique lui permettant de tolérer l'ischémie provoquée par l'absence de vascularisation. Malgré ces progrès techniques et les connaissances accumulées, la chirurgie cardiaque reste une chirurgie à risque dont les complications sont parfois de nature inconnue. Il n'existe pourtant pas de suivi opérationnel de la protection myocardique et les seules indications disponibles pour le chirurgien sont l'arrêt contractile du cœur en début de cardioplégie ou l'apparition de fibrillations cardiaques dénonçant une inefficacité à long terme de la cardioplégie. Parmi les paramètres de mesure pouvant contribuer à la surveillance du myocarde sous cardioplégie, le suivi du changement de température induit par celle-ci pourrait devenir un indicateur pertinent. L'objectif de ce travail de thèse est donc de mettre en place un dispositif de suivi thermique du cœur permettant d'évaluer concrètement la diffusion et l'efficacité de perfusion cardioplégique durant la chirurgie cardiovasculaire.Parmi les méthodes de suivi thermique non invasives implantables en salle d'opération, la thermométrie par ultrasons (TUS) et la thermographie par infrarouges (TIR) ont retenu notre attention. Dans un premier temps, une méthode directe de thermométrie par ultrasons basée sur le principe "d'écho tracking" est expérimentée via un capteur ultrasonore $2,25 MHz mono-élément sur une gamme de température de 10 à 30°C. Cependant la caractérisation du muscle cardiaque par ultrasons et les expérimentations menées en laboratoire ont mis en avant la complexité du milieu nécessitant une calibration préalable, difficile à mettre en place en conditions opératoires. La technique présente tout de même une précision de mesure satisfaisante pour une variation de température inférieure à 10°C. Un modèle d'ajustement est alors proposé afin d'identifier la tendance de réchauffement interne du cœur à partir de la température de surface mesurable via une caméra thermique à infrarouge et par l'estimation volumique du milieu par ultrasons. Le modèle est validé dans un premier temps par simulation par éléments finis et dans un second temps durant des expérimentations sur fantômes et cœur in-vitro.Au final, le dispositif multi-physique TIR et TUS est expérimenté sur modèle in-vivo lors d'opérations, durant lesquelles des sessions de refroidissement par cardioplégie hypothermique sont effectuées. L'étude se conclut sur des premiers résultats de suivi thermique satisfaisants où les températures surfaciques acquises par TIR et l'estimation de l'épaisseur des parois ventriculaires par ultrasons permettent d'obtenir efficacement la tendance de réchauffement du myocarde. Le dispositif multi-physique a également démontré la possibilité d'appliquer une calibration directe de la thermométrie ultrasonore. Cette étude de faisabilité a démontré la possibilité d'un monitoring thermique du cœur de manière non invasive et applicable en temps réel. Ce dispositif pourrait être, après adaptation spécifique, implémenté durant les interventions cardio-vasculaire et fournir un indicateur précieux aux chirurgiens quant à l'efficacité de la protection myocardique. / The success of cardiac surgery essentially depends on tissue preservation. To optimize this latter, a myocardial protection is applied thanks to a hypothermic cardioplegia that confers a marked protective effect to the heart under ischemia. Despite these technical developments, cardiac surgery still presents risks and complications are sometimes of an unknown nature. However, no operational real-time monitoring of myocardial tissue exists. Among the metrics that could be analyzed, the temperature change measurement may be a relevant indicator. The objective of the present thesis is therefore to establish a thermal monitoring system of the heart in a way to evaluate the quality of the cardioplegia perfusion during cardiovascular surgery.Among the non-invasive thermal monitoring methods implantable in the operating room, the ultrasonic thermometry and infrared thermography caught our attention. In the first stages of the study, a direct method of ultrasonic thermometry based on the echo tracking is performed on in-vitro samples with 2.25 MHz ultrasonic sensor in a temperature range between 10 to 30°C. The ultrasonic characterization of the heart muscle and the laboratory experiments brought to the forth an environmental complexity requiring prior calibration that may be difficult to implement in operational conditions. However, the technique has a satisfactory measurement accuracy for temperature variations of less than 10°C.An adjustment model is then proposed to identify the in-depth warming trend of the heart thanks to the surface temperature measurement performed by thermal infrared camera and the medium thickness estimated by ultrasound. The model is validated by finite element simulations and experiments realized on ghosts and in-vitro heart samples.Finally, the device is experimented on in-vivo animal models while hypothermic cardioplegia were conducted. Conclusive results were obtained on the heart thermal monitoring. In particular, the surface temperatures acquired by infrared thermography and the thickness estimation of the ventricular walls by ultrasound allowed an estimation of the myocardial-warming trend.This feasibility study has demonstrated the possibility of heart thermal monitoring, noninvasively and appropriate in real time. After specific adaptation, this device could be implemented during cardiovascular interventions and provide a valuable indicator for the surgeons about the efficacy of myocardial protection.
368

Cooling Strategy Influence on Temperature in ETD Center

Edinger, Oskar January 2021 (has links)
Striving for increased productivity while maintaining hole quality and high process robustness when drilling requires knowledge about the working principles of heat generation, mechanics and a proper cutting fluid that aids in cooling, lubricating and evacuating chips from the cutting zone. If the heat generated in the tool-workpiece and tool-chip interfaces does not exit the cutting zone adequately through the chips, the workpiece material or the redistribution of coolant the hole quality can be impacted negatively and breakdowns may occur which reduces overall productivity. During product testing, a sudden type of drill failure was observed when machining 316L stainless steel. When modifying the coolant design this was avoided which led to the assumption that the failure was caused by a large amount of heat being generated due to poor conductivity in the material combined with insuffcient cooling. However, this theory couldn't be investigated because of a lack of an existing method. To evaluate, three modifications of the CoroDrill 870 with dimensions Ø16mm and length 3xD were designed using Siemens NX 12 to observe whether coolant design choices have a significant impact on heat generation when drilling. To examine this a testing methodology was developed which utilizes IR-thermography and a combination of type K and J thermocouples inserted into the workpiece and onto the back surface, which measures its temperature in the cutting zone. Several tests were conducted with the developed setup to gather a larger data set to reduce impact from random error and to perform further analysis. Although the experiment setup is promising due to being simple and applicable to different materials there are large sources of variation associated with the placement of thermocouples. The results indicate some difference in registered temperature between the modifications however it is diffcult to draw conclusions based on the relatively few trustworthy measurements made. / För att förbättra produktiviteten vid borrning utan att kompromissa på hålkvalité och processäkerhet krävs bakomliggande kunskaper inom områden som, värmebildning, skärförlopp, och kylvätska vilket kyler, smörjer, och transporterar spånor från skärzonen. Om värmen som bildas i ytorna mellan verktyg-ämne och verktyg-spåna inte lämnar skärzonen på ett tillförlitligt sätt genom spånor, ämnet eller genom kylvätskans cirkulation kan hålkvalitén påverkas eller haverier kan orsakas vilket minskar produktivitet. Under en testning som genomfördes där 316L rostfritt stål borrades upptäcktes en ny typ av abrupt brott. När borrens kyllösning modiferades kunde detta fel undvikas varpå man drog slutsatsen att haveriet var en konsekvens av den stora temperaturgradient som bildas då materialets värmeledningsförmåga är relativt dålig. Dessvärre kunde denna teori inte prövas då det saknades en befintlig testmetodik. För att undersöka detta utvecklades tre modifikationer av CoroDrill 870 med dimension Ø16mm och längd 3xD i Siemens NX 12 i syfte att observera huruvida en signifikant temperaturskillnad skulle uppstå. För att utreda detta skapades en testuppställning som kombinerar IR-termografi med termoelement av typ K och typ J, fästa i ämnet respektive påämnets baksida vilket mäter materialets temperatur i skärzon. Ett flertal tester genomfördes med denna uppställning för att samla en större mängd data för fortsatt analys samt för att minska inverkan av slumpmässiga fel.Även om metoden är lovande då den är relativt enkel och tillämpbar på olika material så finns det stora potentiella källor till variation kopplade till mänsklig faktor och placering av termoelement. Resultatet som analyserats antyder att det finns en viss temperaturskillnad mellan modifikationerna men för att göra välgrundade slutsatser skulle fler mätningar behöva genomföras.
369

Možnosti energetických úspor v bytovém domě Merhautova / Possibilities of energy savings in the residential house Merhautova

Bartek, Čeněk January 2018 (has links)
The diploma thesis is about the reduction of the energy intensity of the existing residential house Merhautova. The design documentation is focused on the thermal insulation of the living area, the replacement of windows and doors according to the variant of the design, accessible entrance to the house, loggia on the south side of the building and the replacement of the roofing. At the beginning of the diploma thesis the experimental part of the thermography was performed. Images of the existing object by the thermal camera were taken and building survey for the design documentation of the current state of the building was performed. Within the theoretical calculations the energy performance certificate was processed in options of the entering the thermal bridges. The energy performance certificate with thermal bridges calculated according to the details was compared with the energy performance certificate with estimated thermal bridges. A comparison of two options of the replacement of windows and doors was made in realation of the energy intesity of the building. A preliminary budget of these two options was also calculated with regard to the expected simple return on investment due to the heat saving.
370

Snižování tření mazaných kontaktů změnou tepelné vodivosti materiálů / Improving friction of lubricated contacts by modifying thermal conductivity

Šnevajs, Matěj January 2019 (has links)
This thesis deals with an experimental study regarding the effects of the thermal conductivity of contact bodies on the friction, lubricant film thickness and temperature distribution in EHL contact. The thesis focuses on the configuration of the ball on disc contact. The contact body materials are characterized by a wide range of thermal properties. New contact pairs are proposed and used in the study in order to make the contact bodies’ thermal properties dependent on the behaviour of EHL contact. The colorimetric interferometry method is used to measure the lubricant film thickness and the infrared thermography method is used to observe the temperature distribution in EHL contact. The author presents the assumed mechanism of heat transfer within EHL contact on the basis of different heat transfer mechanisms. The same conditions – such as the Hertz pressure, mean entrainment speed, sliding speed and ambient temperature – are induced for all the contact pair combinations. That is why the differences in the results are attributed to the different thermal phenomena in the contact, caused by the thermal properties of the contact bodies. In the case of contact bodies with a reduced heat dissipation capability, a reduction of the friction coefficient of up to 50 % is observed, which is attributed to an increase in the lubricant temperature, resulting in a decrease in its viscosity. This is confirmed by the infrared thermography method, whereby a significantly higher lubricant temperature is observed in the case of a combination of contact materials with a lower heat dissipation capability.

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