Ce travail porte sur le développement d’une technique de calorimétrie sans contact pour des écoulements diphasiques. Ces derniers sont réalisés sur la forme d’un train gouttes dans des tubes de taille millimétriques dans des supports isopériboliques. L’idée principale est de coupler la Thermographie Infrarouge et les outils microfluidiques pour proposer une technique adapté de mesure. L’utilisation de la microfluidique rend possible l’utilisation de très faibles volumes réactionnels limitant ainsi tout risque lié à la dangerosité des réactions réalisées au sein des gouttes, l’outil Infrarouge permet de suivre ces écoulements avec grande précision. Les résultats de ces travaux de thèse montrent que l’outil est capable d’estimer des propriétés thermo-physiques des écoulements non réactifs. Ainsi, que de caractériser de réactions chimiques en termes d’enthalpie et cinétique. Finalement cette dernière caractérisation a été comparée aux techniques classiques pour mettre en évidence la précision et les avantages de l’outil développé / This work concerns the development of a non-contact calorimeter for two-phase flow characterization. The biphasic flow is performed under a droplet configuration inside millimetric tubings which are inserted into the isoperibolic chip. The main idea is to combine the Infrared Thermography and microfluidic tools to propose a suitable technique for accurate measurements. Microfluidics enables the use of small reaction volumes thus limiting any risk of dangerous reactions inside droplets, the Infrared tool enables to monitor the thermal signature of these flows with high accuracy. The results of this thesis show that this tool is able to estimate the thermophysical properties of non-reactive flows. Also , it is possible to characterize chemical reactions in terms of enthalpy and kinetics . Finally the latter characterization was compared to conventional techniques to demonstrate the benefits and the precision of the tool.

L’un des accidents de dimensionnement d’un réacteur à eau pressurisée est l’Accident de Perte de Réfrigérant Primaire (APRP). L’évènement initiateur d’un tel accident est une brèche sur le circuit primaire du réacteur entrainant une perte d’inventaire en eau, et de ce fait conduit à un assèchement des assemblages combustibles. En conséquence, une augmentation considérable de la température surviendrait à l’intérieur du cœur du réacteur. Ainsi, les gaines de combustible peuvent éventuellement se déformer et des zones dites ballonnées apparaitre. Ces zones vont avoir un fort impact sur l’efficacité du refroidissement du cœur du réacteur. Pour contribuer à l’étude thermohydraulique d’un APRP, la présente thèse a pour but la caractérisation expérimentale des interactions entre un écoulement diphasique de vapeur/gouttes et une zone partiellement bouchée. Afin de reproduire un tel scénario, le banc expérimental thermohydraulique COLIBRI a été conçu. Plusieurs configurations géométriques de la zone ballonnée, caractéristiques d’un APRP, sont analysées (longueur et taux de bouchage associés au ballonnement). Afin de caractériser les échanges thermiques paroi/fluide ainsi que la dynamique des gouttes, des diagnostics optiques et thermiques sont utilisés : l’Anémométrie Phase Doppler (PDA) pour mesurer le diamètre et la vitesse des gouttes, la Fluorescence Induite par Laser (LIF) pour mesurer la température des gouttes et la Thermographie Infrarouge (IR) afin d’estimer le flux de chaleur extrait du tube par l’écoulement. En parallèle, une modélisation du problème a été développée afin d’obtenir une approche théorique de la capacité de refroidissement de l’écoulement diphasique. Le système d’équations décrivant la conservation de la masse, de la quantité de mouvement et de l’énergie permettra d’estimer l’impact respectif des différents mécanismes de transferts thermiques mis en jeu ainsi que l’évolution spatio-temporelle des paramètres thermohydrauliques / During a Loss of Coolant Accident (LOCA) in a Pressurized Water Reactor (PWR), caused by a break or a leakage on the primary circuit, partial or even complete drying of the fuel assemblies may occur. In these conditions, the fuel temperature increases, leading to a significant deformation and rupture of the fuel rod cladding. The cooling flow might be impaired, according to the size and distribution of the deformed zones within the fuel assemblies during the emergency cooling phase (Reflooding phase). To contribute to the thermalhydraulic study of the reflooding phase, this study aims to characterize experimentally the coolability of a representative deformed sub-channel by a steam-droplets flow under LOCA conditions. In order to reproduce such a scenario, the experimental thermal-hydraulic set-up COLIBRI was designed. Several geometrical blockage configurations are analyzed (Blockage ratios and axial lengths). Three measurement techniques are set up to follow the cooling transient phase of each experience: Phase Doppler Anemometry (PDA) in order to obtain both velocity and diameter of droplets, Laser Induced Fluorescence (LIF) to measure the mean droplet temperature and Infrared thermography to estimate the heat flux removed by the two-phase flow. Additionally, a one-dimensional mechanistic model, taking into account of the heat transfers mechanisms in the post-dry out region, is developed in order to analyze the experimental data and identify each one of the wall-to-fluid heat transfers (radiation with vapor and droplets, convection with vapor, evaporation, and droplet impact)

Made available in DSpace on 2016-08-15T20:31:17Z (GMT). No. of bitstreams: 1 JoaoBFSJ_DISSERT.pdf: 848742 bytes, checksum: 5da6694c94e2b15db5ab8ba10f875e9a (MD5) Previous issue date: 2014-02-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study aimed to evaluate the effect of corn particle size on performance, egg quality and sensible heat loss, beyond of the regional differences in surface temperature of naked neck laying hens by infrared thermography. In Mossoró-RN, 60 label Rouge chickens in laying stage were distributed in a completely randomized design, where were fed with diets containing different corn particle size or geometric mean diameter (GMD) of 605 µm, 1030 µm and 2280 µm. Environmental variables were measured in center of the shed: black globe temperature (TG) and air (TA), wind speed (U) and relative humidity (RH). Rectal temperature (RT), respiratory rate (RR) and surface temperature (TS) were measured in each bird once a week. For sensible heat loss, RT, RR and TS, the analysis of variance was performed by least squares method and comparison of means by Tukey's test (p<0.05). The results showed that the GMD 2280 µm increased the feed intake, causing elevation in body temperature and respiratory rate in response to increased metabolic heat production. The hens fed with this same GMD showed lower quality eggshell. The sensible heat transfer was, during the study, a heat dissipation mechanism, where the increase in radiation and TA levels caused significant decrease in heat loss by radiation, but heat loss by convection was high in high TA due to increased wind speed. There are regional differences in the TS, where the legs act as thermal windows / Objetivou-se com este estudo avaliar as diferenças regionais na temperatura superficial através de imagens térmicas e o efeito do ambiente semiárido e do tamanho da partícula do milho no desempenho, qualidade do ovo e perda de calor sensível de poedeiras do pescoço pelado. Em Mossoró-RN, 60 galinhas da linhagem Label Rouge em fase de postura foram distribuídas em um delineamento inteiramente casualizado, onde foram fornecidas rações com diferentes tamanhos da partícula do milho ou diâmetro geométrico médio (DGM) de 605 µm, 1030 µm e 2280 µm. As variáveis ambientais foram aferidas no centro do galpão: temperatura do globo negro (TG) e do ar (TA), velocidade do vento (U) e umidade relativa (UR). A temperatura retal (TR), frequência respiratória (FR) e temperatura superficial (TS) foram aferidas em cada ave uma vez por semana. Para a perda de calor sensível, TR, FR e TS a análise de variância foi realizada pelo método dos quadrados mínimos e a comparação de médias para todas as variáveis pelo teste de Tukey (p<0.05). Os resultados mostraram que o DGM igual a 2280 µm aumentou o consumo de ração, causando elevação na temperatura corporal e frequência respiratória como resposta à maior produção de calor metabólico. As aves alimentadas com este mesmo DGM apresentaram qualidade da casca do ovo inferior. A transferência de calor sensível apresentou-se com um mecanismo de dissipação térmica, onde o aumento nos níveis de radiação e TA causaram diminuição significativa na perda de calor por radiação, mas a convecção foi elevada em alta TA devido ao aumento na movimentação do ar. Houve diferença regional na TS, onde as patas atuaram como janelas térmicas

Un modèle semi-analytique permettant de simuler le transfert thermique conjugué dans un mini/macro canal plan soumis à des sources de chaleur surfaciques localisées sur les faces externes et variantes en fonction du temps, a été présenté et vérifié. Plus le diamètre hydraulique du canal est petit, plus la caractérisation expérimentale interne (mesure des températures et des flux) en régime thermique permanent ou transitoire à l'aide des capteurs internes est délicate. Une méthode non-intrusive permettant d'estimer les conditions internes à partir des mesures de température par thermographie infrarouge sur les faces externes et d'un modèle semi-analytique, a été effectuée. Comme le coefficient de transfert convectif forcé classique perd son sens en régime instationnaire, une approche alternative basée sur une fonction de transfert, valable pour un système linaire et invariant dans le temps a été mise en œuvre. Cette fonction peut être calculée analytiquement (uniquement pour une géométrie simple) ou estimée expérimentalement (géométrie complexe). Grâce au caractère intrinsèque de cette fonction de transfert, deux capteurs virtuels ont été conçus : capteur virtuel de température et détecteur d'encrassement permettent respectivement d'estimer les températures internes et de détecter l'encrassement qui peut avoir lieu dans l'échangeur à partir des mesures de températures sur les faces externes / A semi-analytical model allowing to simulate the transient conjugate heat transfer in mini/macro plane channel subject to a heat source(s) localized on the external face(s), was presented and verified. The developed model takes into account advection-diffusion in the fluid and conduction in the solid. As the hydraulic diameter of the channel becomes small, the internal experimental characterization (measurement of temperature and heat flux) using internal sensors become tricky because internal sensors located may compromise the structural integrity of the whole system. A non-intrusive method for estimating the internal conditions from infrared temperature measurements on the external faces using the semi-analytical model was performed. Since the classic convective heat transfer coefficient loses its meaning in transient state, an alternative approach based on a transfer function, valid for Linear Time-Invariant (LTI) systems, was highlighted. This function can be calculated analytically only for a simple geometry. For complex geometries it can be estimated experimentally. Thanks to intrinsic character of this function, two characterization methods were designed. The first to estimate the temperature at a point from a measurement at another point in the system (virtual temperature sensor). The second method concerns the detection of fouling layers that may appear in the heat exchanger from temperature measurements on the external faces

O estímulo vibratório gerado pela utilização das plataformas vibratórias tem sido aplicado como método eficaz para promover desempenho esportivo e também na reabilitação de pacientes com diversificadas disfunções. Acredita-se que a vibração de corpo inteiro (VCI) é capaz de diminuir os déficits de ativação muscular voluntária através de reflexos de estiramento neuromuscular, tornando-se um meio eficaz e de fácil aplicabilidade para pacientes com maiores incapacitações. Resultados controversos na literatura, com relação aos benefícios dos estímulos vibratórios, tornam a escolha dos parâmetros do equipamento (frequência, amplitude, tempo de exposição e modo de vibração) um desafio na obtenção dos melhores resultados. Assim, o objetivo desta tese visa a avaliação dos efeitos fisiológicos agudos da vibração de corpo inteiro (sensibilidade cutânea tátil e dolorosa, equilíbrio, temperatura superficial da pele, transmissibilidade da vibração) e a construção de um mapa de percepção corporal da VCI. Foram utilizados diferentes parâmetros e marcas desses equipamentos. Para investigar cada variável, quatro diferentes estudos foram realizados separadamente. O primeiro estudo investigou os efeitos da VCI na sensibilidade cutânea vibratória medidos a 30 Hz (corpúsculos de Meissner) e 200Hz (corpúsculos de Pacini) e de toque-pressão dos pés de 20 sujeitos normais e o tempo de duração dos efeitos da vibração nesses receptores. Como principais resultados, foram constatadas que as descargas aferentes dos mecanorreceptores de adaptação rápida foram fortemente afetadas pela vibração assim como a sensibilidade de toquepressão. Após 10 min de exposição à VCI o tempo de recuperação para a sensibilidade voltar aos limiares basais nos pés foi entre 2 e 3 h. Para continuar elucidando os efeitos agudos pós-exercício com vibração, um segundo estudo foi realizado avaliando variáveis fisiológicas em quatro diferentes frequências de exposição de VCI (30, 35, 40, 44 Hz). Foram avaliadas pressão arterial, frequências cardíaca e respiratória, temperatura axilar e a temperatura cutânea através de termografia por infravermelho dos membros inferiores dos 24 participantes avaliados. Por fim, o equilibro desses indivíduos foi avaliado através das análises dos deslocamentos, da velocidade e da área do centro de pressão (COP), em uma plataforma de força. Os dados do segundo estudo mostraram que, para as frequências de 40 e 44 Hz do equipamento, houve uma alteração significativa para as variáveis velocidade e comprimento ântero-posterior do centro de pressão. Além disso, durante a vibração e 10 min após, a temperatura dos membros inferiores foi reduzida, provavelmente em virtude da vasoconstrição gerada. Na investigação da sensibilidade dolorosa um terceiro estudo foi proposto, tendo em vista que as vias dos mecanorreceptores de sensibilidade cutânea tátil diferem daqueles relacionados com a sensibilidade dolorosa. Um modelo de dor crônica com ratos Wistar foi realizado e os animais foram tratados com VCI, esteira e a combinação de esteira com VCI. Como principais resultados deste estudo, os grupos tratados com VCI mostraram redução significativa da sensibilidade de toque-pressão após todas as sessões em comparação aos demais grupos. Efeitos analgésicos através do tempo de latência medidos com o hot plate foram encontrados após o terceiro dia de tratamento com 5 min de exposição por dia à VCI, nos primeiros 5 dias e 10 min nos 5 dias subsequentes. Como finalização das variáveis de interesse, o último estudo combinou dados quantitativos advindos da acelerometria (com medições na cabeça, quadril e tíbia) com dados qualitativos através da escala de Borg. Sessenta e cinco adultosjovens foram avaliados e este estudo propôs um método para escolher os diversificados parâmetros da plataforma vibratória, para alcançar os efeitos desejados na reabilitação ou desempenho esportivo. Este estudo mostrou que os índices de percepção de severidade medidos através da escala de Borg corresponderam com os dados quantitativos da acelerometria e assim os parâmetros do equipamento podem ser escolhidos com base na sensação subjetiva proveniente da escala de Borg. Os níveis de desconforto no equipamento podem estar relacionados com a frequência de ressonância das diferentes partes do corpo. Futuros estudos devem considerar aplicações clínicas da plataforma vibratória em pacientes com dor crônica musculoesquelética utilizando o modelo para escolha dos parâmetros do equipamento proposto nesta tese. / The vibratory stimuli generated by the use of vibrating platforms have been used as an effective method to promote sports performance and also in the rehabilitation of patients with several dysfunctions. It is believed that the whole body vibration (WBV) is able to decrease the deficits in voluntary muscle activation by neuromuscular stretch reflexes making it an efficient and easy exercise method applied to patients with greater disabilities. Controversial results in the literature regarding the benefits of the vibratory stimuli make the choice of the equipment parameters (frequency, amplitude, time of exposure and vibration mode) a challenge in getting the best results. The goal of this dissertation involves the evaluation of the acute physiological effects of whole body vibration (skin tactile and pain sensitivity, balance, skin temperature and vibration transmissibility) and the construction of a WBV perception body map. Parameters settings and different brands of these devices were used. To investigate each variable, four different studies were conducted separately. The first study investigated the effects of WBV on fast adapting mechanoreceptors measured at 30 Hz (Meissner corpuscles) and 200Hz (Pacinian corpuscles) and touch-pressure sensitivity from the right foot of 20 health subjects and the duration of the vibration effects on these receptors. The main results show that the afferent discharges of the fast adapting mechanoreceptors are strongly affected by vibration and sensitivity of touch-pressure was also impaired. After a single 10 minutes exposure to WBV, the time required to recover baseline tactile sensitivity on the feet was between 2 and 3 hours. To further elucidate the acute postexercise vibration effects, a second study was conducted assessing physiological variables at four different WBV frequencies (31, 35, 40, 44 Hz). Blood pressure, heart and respiratory rates, skin temperature and balance were measured. Skin temperature was measured by an infrared thermography of the lower limbs of 24 subjects. Balance was accessed with a force plate through the analysis of the center of pressure (COP) velocity, area and displacements variables. The results from this study show that for 40 and 44 Hz of the device’s frequencies, a significant decrease in balance was found for the center of pressure variables velocity and anterior-posterior displacement. Also, during WBV exposition and 10 minutes post vibration, the temperature of the lower limbs was reduced, probably due to vasoconstriction. To investigate the variable "pain", a third study was proposed, considering that the pathways and receptors of the cutaneous touch-pressure and vibration sensitivity differ from those related to pain sensitivity, the C and A fibers. A chronic pain model was applied in male Wistar rats and the animals were treated with WBV exercise (vibration platform), a low intensity exercise (treadmill) and a combined treatment involving both. The main results show that the groups treated with WBV showed a significant reduction in sensitivity to touchpressure after every session compared to the other groups. Analgesic effects through the time latency measured by the hot plate were found after the third treatment day with 5 min of exposure to WBV during the first 5 days and 10 min next 5 days. As completion of the fourth variable of interest, the last study by deriving quantitative data from accelerometry (with measurements on the head, hip and tibia) was combined with qualitative data arising from the Borg scale. Sixty five health young adults were measured and the study proposes a method for choosing the parameters settings of the vibrating platform, to achieve the desired goals in rehabilitation or sports performance. Discomfort perception ratings measured by the Borg scale corresponded well with the measured acceleration magnitudes and so the parameters settings of the device can be chosen based on the subjective sensation from the Borg scale. The level of discomfort ratings might be related to the frequency resonance phenomena of body parts. Future clinical applications with vibration platform in patients with muscle-skeletal chronic pain should be considered applying the model for choosing the parameter settings of the device proposed in this dissertation.

La compréhension des phénomènes se déroulant lors de l’impact d’une goutte sur une paroi chaude est essentielle à l’optimisation des systèmes de refroidissement par sprays. Lorsque la température de paroi est élevée, un film de vapeur se forme quasi-instantanément entre la goutte et la paroi chaude. Ce film modifie le comportement hydrodynamique des gouttes et réduit considérablement les échanges de chaleur et de masse par rapport à un impact mouillant. La modélisation de ces phénomènes est complexe en raison des nombreux couplages entre les transferts de chaleur et de masse et la dynamique d’impact de la goutte. Pour aborder ce sujet, des techniques de mesure optiques ont été développées spécifiquement. L’imagerie de fluorescence induite par plan laser à deux couleurs permet de caractériser la distribution de la température à l’intérieur des gouttes. Des images du champ de température, résolues à la fois spatialement et temporellement, sont rendues possible grâce à l’utilisation d’un nouveau couple de colorants fluorescents conservant une grande sensibilité à la température quand ils sont excités par un laser pulsé nanoseconde d’une énergie de plusieurs centaines de mJ. En parallèle, la thermographie infrarouge a été utilisée pour déterminer la température de la surface d’impact en saphir. Pour cela, cette dernière est recouverte d’une couche de quelques centaines de nanomètres de TiAlN, émissif dans l’IR alors que le saphir est transparent. Les images haute cadence sont analysées par un modèle d’inversion, prenant en compte la conduction thermique dans le saphir, afin d’estimer la densité de flux thermique au niveau de la surface d’impact. L’épaisseur du film de vapeur est également déduite de ces mesures sous l’hypothèse, justifiée a posteriori, d’une conduction thermique prépondérante dans le film de vapeur. Une étude de l’impact de gouttes d’eau est réalisée en faisant varier la vitesse d’impact et la température des gouttes avant impact, ainsi que la température de paroi. Dans la plupart des cas, la chaleur extraite à la paroi est comparable à celle transférée au liquide pour l’échauffer. Lorsque la température de paroi se rapproche et dépasse la température de Leidenfrost, les transferts de chaleur deviennent de plus en plus sensibles au nombre de Weber, et de moins en moins dépendant de la température de paroi. L’épaisseur du film de vapeur est affectée par des instabilités, dont les caractéristiques (longueur d’onde, amplitude) sont étudiées à partir des images IR. Finalement, un modèle 1D semi empirique est proposé pour décrire l’échauffement des gouttes et la croissance du film de vapeur. La pression exercée par la goutte sur le film de vapeur se dissipe très vite à l’impact, si bien que la croissance du film de vapeur est gouvernée par la conduction de la chaleur vers la goutte et non par la dynamique de l’impact / The understanding of phenomena occurring at the impact of a droplet onto a hot wall is crucial for the optimization of spray cooling systems. When the temperature of the wall is high, a vapor layer appears quasi-instantaneously between the droplet and le wall. This film of vapor modifies the hydrodynamic behavior of the droplet and highly reduce the heat and mass transfers in comparison with a wetting impact. Modelling these phenomena is complex because of the numerous coupling between the heat and mass transfers and the fluids dynamic. To get some insights into this phenomenon, optical diagnostic techniques have been developed. Two color planar laser induced fluorescence imaging allows characterizing the distribution of the temperature inside the droplet. Images of the temperature fields, resolved both spatially and temporally, are recorded thanks to the use of a couple of fluorescent dyes keeping a high temperature sensitivity even when they are excited by a nanosecond pulsed laser with and an energy of hundreds m J. In parallel, the infrared thermography is used to determine the temperature of the impinged surface made of sapphire. For that, this surface is coated with a thin film (about 300 nanometers) of TiAlN, highly emissive in the IR domain as opposed to the sapphire which is transparent in it. High frame rate image sequences are analyzed thanks to an analytical inversion model, taking into account the thermal conduction in the sapphire, in order to estimate the heat flux density at the impact surface. The thickness of the vapor layer was also deduced from this measurements thanks to the hypothesis of a dominant thermal conduction in the vapor layer. A study of water drop impact was performed with different impact speeds, wall temperatures and different drop injection temperatures. In most of the cases, the heat flux extracted from the wall in close to the flux transferred to the liquid phase of the droplet. When the wall temperature approaches or exceeds the Leidenfrost temperature, the transfers become more sensitive to the Weber number and less sensitive to the wall temperature. The vapor layer thickness is affected by instabilities whose caracteristics (wavelengths, amplitude) were investigated from the IR images. Eventually, a 1-Dsemi-empirical model is given for describing the heating of the liquid part of the droplet and the growth of vapor layer. The effect of the pressure exerted by the droplet onto the vapor film rapidly decreases during the impact process, so that the growth of the vapor film is only driven by the heat transferred by conduction to the droplet and not by dynamical parameters such as the impact velocity

Les industriels du secteur aéronautique sont, de plus en plus, à la recherche de procédés de fabrication à forte valeur ajoutée sans modifier les paramètres d’infusabilité de la résine lorsque l’on change de tissu. Nous avons donc mis en œuvre le procédé d’infusion de résine liquide sur des composites carbone/époxyde de forte épaisseur (e>4 mm) en modifiant les cycles de polymérisation, les matériaux utilisés et les séquences d’empilement. Tous les tissus sont en carbone et la résine utilisée est la résine commerciale RTM6. Les structures aéronautiques sont sollicitées, en service, de différentes façons. Elles peuvent être accidentellement impactées par des engins de maintenance, des outils, de la grêle ou toute autre forme d’impact. Le problème pour les industriels est de pouvoir détecter l’endommagement créé et de comprendre les mécanismes mis en jeu lors de l’impact mais aussi leur évolution pendant un cyclage en fatigue. Nos travaux se sont donc inscrits dans cet objectif et différentes méthodes ont été mises en œuvre : détection de défauts d’impact et suivi en temps réel par thermographie infrarouge, détection de l’indentation résiduelle par numérisation par projection de franges. Parallèlement, le phénomène d’impact a aussi été traité par une étude statistique par plan d’expérience et une modélisation avancée a été créée avec l’utilisation de surfaces cohésives. / Aeronautical manufacturers are looking for the best manufacturing process giving high benefits. Moreover, it has to be implemented easily with change of woven fabrics. So, we realize thick carbon/epoxy composites (t>4 mm) by modifying cure cycles, woven fabrics and lay-up sequences. Concerning the constituent materials of the composites, woven fabrics are carbon made and the resin is the commercial product named RTM6. Aeronautical structures can be unfortunately stressed, in service, with different solicitations: holding, engine impact, falling objects impacts or other way. The main problem for industrials is to be able to detect the created damage, to understand the phenomena dealing with it and the damage evolution during fatigue cycles. By following this direction, different methods are developed: impact damage defects detection and evolution monitored with infrared thermography, impact residual depth measurement by fringes projection digitalization. At the same time, a statistical study made by design of experiments is completed. A numerical impact modeling is also developed by using cohesive surfaces.

O estímulo vibratório gerado pela utilização das plataformas vibratórias tem sido aplicado como método eficaz para promover desempenho esportivo e também na reabilitação de pacientes com diversificadas disfunções. Acredita-se que a vibração de corpo inteiro (VCI) é capaz de diminuir os déficits de ativação muscular voluntária através de reflexos de estiramento neuromuscular, tornando-se um meio eficaz e de fácil aplicabilidade para pacientes com maiores incapacitações. Resultados controversos na literatura, com relação aos benefícios dos estímulos vibratórios, tornam a escolha dos parâmetros do equipamento (frequência, amplitude, tempo de exposição e modo de vibração) um desafio na obtenção dos melhores resultados. Assim, o objetivo desta tese visa a avaliação dos efeitos fisiológicos agudos da vibração de corpo inteiro (sensibilidade cutânea tátil e dolorosa, equilíbrio, temperatura superficial da pele, transmissibilidade da vibração) e a construção de um mapa de percepção corporal da VCI. Foram utilizados diferentes parâmetros e marcas desses equipamentos. Para investigar cada variável, quatro diferentes estudos foram realizados separadamente. O primeiro estudo investigou os efeitos da VCI na sensibilidade cutânea vibratória medidos a 30 Hz (corpúsculos de Meissner) e 200Hz (corpúsculos de Pacini) e de toque-pressão dos pés de 20 sujeitos normais e o tempo de duração dos efeitos da vibração nesses receptores. Como principais resultados, foram constatadas que as descargas aferentes dos mecanorreceptores de adaptação rápida foram fortemente afetadas pela vibração assim como a sensibilidade de toquepressão. Após 10 min de exposição à VCI o tempo de recuperação para a sensibilidade voltar aos limiares basais nos pés foi entre 2 e 3 h. Para continuar elucidando os efeitos agudos pós-exercício com vibração, um segundo estudo foi realizado avaliando variáveis fisiológicas em quatro diferentes frequências de exposição de VCI (30, 35, 40, 44 Hz). Foram avaliadas pressão arterial, frequências cardíaca e respiratória, temperatura axilar e a temperatura cutânea através de termografia por infravermelho dos membros inferiores dos 24 participantes avaliados. Por fim, o equilibro desses indivíduos foi avaliado através das análises dos deslocamentos, da velocidade e da área do centro de pressão (COP), em uma plataforma de força. Os dados do segundo estudo mostraram que, para as frequências de 40 e 44 Hz do equipamento, houve uma alteração significativa para as variáveis velocidade e comprimento ântero-posterior do centro de pressão. Além disso, durante a vibração e 10 min após, a temperatura dos membros inferiores foi reduzida, provavelmente em virtude da vasoconstrição gerada. Na investigação da sensibilidade dolorosa um terceiro estudo foi proposto, tendo em vista que as vias dos mecanorreceptores de sensibilidade cutânea tátil diferem daqueles relacionados com a sensibilidade dolorosa. Um modelo de dor crônica com ratos Wistar foi realizado e os animais foram tratados com VCI, esteira e a combinação de esteira com VCI. Como principais resultados deste estudo, os grupos tratados com VCI mostraram redução significativa da sensibilidade de toque-pressão após todas as sessões em comparação aos demais grupos. Efeitos analgésicos através do tempo de latência medidos com o hot plate foram encontrados após o terceiro dia de tratamento com 5 min de exposição por dia à VCI, nos primeiros 5 dias e 10 min nos 5 dias subsequentes. Como finalização das variáveis de interesse, o último estudo combinou dados quantitativos advindos da acelerometria (com medições na cabeça, quadril e tíbia) com dados qualitativos através da escala de Borg. Sessenta e cinco adultosjovens foram avaliados e este estudo propôs um método para escolher os diversificados parâmetros da plataforma vibratória, para alcançar os efeitos desejados na reabilitação ou desempenho esportivo. Este estudo mostrou que os índices de percepção de severidade medidos através da escala de Borg corresponderam com os dados quantitativos da acelerometria e assim os parâmetros do equipamento podem ser escolhidos com base na sensação subjetiva proveniente da escala de Borg. Os níveis de desconforto no equipamento podem estar relacionados com a frequência de ressonância das diferentes partes do corpo. Futuros estudos devem considerar aplicações clínicas da plataforma vibratória em pacientes com dor crônica musculoesquelética utilizando o modelo para escolha dos parâmetros do equipamento proposto nesta tese. / The vibratory stimuli generated by the use of vibrating platforms have been used as an effective method to promote sports performance and also in the rehabilitation of patients with several dysfunctions. It is believed that the whole body vibration (WBV) is able to decrease the deficits in voluntary muscle activation by neuromuscular stretch reflexes making it an efficient and easy exercise method applied to patients with greater disabilities. Controversial results in the literature regarding the benefits of the vibratory stimuli make the choice of the equipment parameters (frequency, amplitude, time of exposure and vibration mode) a challenge in getting the best results. The goal of this dissertation involves the evaluation of the acute physiological effects of whole body vibration (skin tactile and pain sensitivity, balance, skin temperature and vibration transmissibility) and the construction of a WBV perception body map. Parameters settings and different brands of these devices were used. To investigate each variable, four different studies were conducted separately. The first study investigated the effects of WBV on fast adapting mechanoreceptors measured at 30 Hz (Meissner corpuscles) and 200Hz (Pacinian corpuscles) and touch-pressure sensitivity from the right foot of 20 health subjects and the duration of the vibration effects on these receptors. The main results show that the afferent discharges of the fast adapting mechanoreceptors are strongly affected by vibration and sensitivity of touch-pressure was also impaired. After a single 10 minutes exposure to WBV, the time required to recover baseline tactile sensitivity on the feet was between 2 and 3 hours. To further elucidate the acute postexercise vibration effects, a second study was conducted assessing physiological variables at four different WBV frequencies (31, 35, 40, 44 Hz). Blood pressure, heart and respiratory rates, skin temperature and balance were measured. Skin temperature was measured by an infrared thermography of the lower limbs of 24 subjects. Balance was accessed with a force plate through the analysis of the center of pressure (COP) velocity, area and displacements variables. The results from this study show that for 40 and 44 Hz of the device’s frequencies, a significant decrease in balance was found for the center of pressure variables velocity and anterior-posterior displacement. Also, during WBV exposition and 10 minutes post vibration, the temperature of the lower limbs was reduced, probably due to vasoconstriction. To investigate the variable "pain", a third study was proposed, considering that the pathways and receptors of the cutaneous touch-pressure and vibration sensitivity differ from those related to pain sensitivity, the C and A fibers. A chronic pain model was applied in male Wistar rats and the animals were treated with WBV exercise (vibration platform), a low intensity exercise (treadmill) and a combined treatment involving both. The main results show that the groups treated with WBV showed a significant reduction in sensitivity to touchpressure after every session compared to the other groups. Analgesic effects through the time latency measured by the hot plate were found after the third treatment day with 5 min of exposure to WBV during the first 5 days and 10 min next 5 days. As completion of the fourth variable of interest, the last study by deriving quantitative data from accelerometry (with measurements on the head, hip and tibia) was combined with qualitative data arising from the Borg scale. Sixty five health young adults were measured and the study proposes a method for choosing the parameters settings of the vibrating platform, to achieve the desired goals in rehabilitation or sports performance. Discomfort perception ratings measured by the Borg scale corresponded well with the measured acceleration magnitudes and so the parameters settings of the device can be chosen based on the subjective sensation from the Borg scale. The level of discomfort ratings might be related to the frequency resonance phenomena of body parts. Future clinical applications with vibration platform in patients with muscle-skeletal chronic pain should be considered applying the model for choosing the parameter settings of the device proposed in this dissertation.

Un système microfluidique à onde élastique de surface a été développé dans le but de réaliser une réaction d'amplification de brins d'ADN par PCR. Nous avons principalement étudié la température et l'uniformité de l'échauffement des gouttes irradiées par des ondes de type Rayleigh. Ces dernières sont générées à la surface d'un substrat piézoélectrique de Niobate de Lithium (LiNbO3). Nous avons pensé un système consommant le moins d'énergie électrique possible pour atteindre les températures désirées et permettant une meilleure uniformité de la température des gouttes. Pour cela, un dispositif à transducteur enterré a été réalisé sous une couche isolante de silice. Les gouttes sont ainsi directement posées sur le transducteur ce qui limite les pertes et améliore la répartition de la chaleur au sein des gouttes. Nous avons ensuite vérifié que les réactifs de la PCR ne sont pas affectés par les ondes de Rayleigh ce qui laisse présager que la PCR peut être réalisée à l'aide d'un système d'échauffement par ondes de Rayleigh. Par ailleurs, le déplacement de goutte sur ce type de substrat de LiNbO3 est important pour des applications de type laboratoire sur puce. Ce substrat ayant des propriétés hydrophiles, des revêtements ont été développés afin de minimiser la force nécessaire à l'actionnement des gouttes. Dans ces travaux, nous proposons un nouveau type de couche à base de copolymère P(VDF-TrFe) dont la fabrication est simplement réalisée par dissolution et étalement par spin-coating. Nous avons montré que ce type de couche n'affecte que très peu la propagation des ondes de Rayleigh et les propriétés hydrophobes sont équivalentes à d'autres revêtements / In this work, a microfluidic system based on surface acoustic wave has been developed in order to achieve the amplification of DNA strands by temperature cycling (PCR). We studied mainly the temperature and the heat uniformity of microdroplets irradiated by Rayleigh waves. These waves are generated at the surface of a lithium niobate substrate. We propose a system allowing better temperature uniformity within microdroplets with an optimal energy consumption. For this, a device with buried transducer has been developed under an insulating layer (Silice). The droplets are then placed directly on the transducer which limits losses and improves the distribution of heat within the microdroplets. We then verified that the PCR reagents are not affected by the Rayleigh waves which suggests that PCR can be performed using a heating system by Rayleigh waves. Moreover, the move of microdroplets on this kind of LiNbO3 substrate is important for lab on chip applications. This substrate having hydrophilic properties, some coatings have been developed to minimize the required force to actuate the microdroplets. In this work, we developed a new hydrophobic layer based on copolymer P(VDF-TrFe) whose production is simply made by dissolving and spreading by spin-coating. We have shown that this kind of layer is compatible with Rayleigh waves and that the hydrophobic properties are equivalent to other coatings

Les impacts de gouttes sur paroi chaude sont présents dans de multiples domaines, tels que l'injection de diesel sous forme de spray dans des moteurs à combustions internes, ou le traitement thermiques de l'acier dans le domaine de la sidérurgie. L'étude de l'interactions goutte/paroi permet de mieux comprendre les phénomènes thermiques mis en jeu, et ainsi d'aboutir à des économies d'énergies et d'eau. De nombreux travaux portent sur cette thématique, mais ils présentent des résultats divergents et uniquement basés sur l'étude de la paroi chaude. Cette thèse a pour but d'apporter des mesures expérimentales sur les caractéristiques inconnues en étudiant les gouttes. Pour cela, un dispositif expérimental a été mis au point afin de mener à bien l'ensemble des mesures souhaitées. Les diverses techniques de mesures de température utilisées sont présentées, et une attention plus particulière a été portée sur le développement de la technique de fluorescence induite par plan laser qui permet d'accéder au champ de température des gouttes durant leur impact. Cette méthode, combinée à une technique de thermographie par caméra infrarouge couplée à un modèle de conduction inverse, permet d'extraire les paramètres concernant l'aspect thermique, et de déterminer de nouvelles caractéristiques inédites, telles que l'échauffement des gouttes, l'évaporation relative de celles-ci ou encore l'efficacité de refroidissement. Les parts respectives jouées par la chaleur sensible et l'évaporation des gouttes sont tirées de cette dernière. Enfin, l'aspect dynamique est également abordé aboutissant au développement d'une technique d'ombroscopie rapide. Cette dernière a permis, grâce à la combinaison de mesures de diamètres précises et d'une fréquence d'acquisition élevée, d'extraire les paramètres dynamiques de l'impact tels que la vitesse et taille des gouttes, ou d'autres paramètres relatif au type d'impact rencontrés à l'aide d'un algorithme de suivi de particules développé durant la thèse / The droplet impact onto a heated wall interaction can be found in mutiples fields, such as internal combustion engines or the steel industry, specially in the thermal treatment of the steel where high energy dissipation rate is required. The study of this interaction should grant a better understanding of this phenomena, and thus, allow the enhancement of these processes and reduce the energy and water consumption. Several studies have already been carried out on this subjet but a great majority of them, whose results present great divergence, only consider the heated wall, neglecting the outgoing of the droplet. This thesis put the emphasis on the liquid phase where currently no data exist to our knowledge, with the help of multiples experimental technics that have been developped. A general experimental setup has been made in order to make all the wanted measurements. The measurement techniques used in this study are first presented, to begin with the planar laser induced fluorescence, which allow us to know the droplet temperature during the impact. Used with an infrared thermography technique coupled with an inverse conduction model, it is possible to extract some important parameter regarding the thermal aspect, such as the droplet heating, the relative evaporation ratio or the cooling efficiency. This latter can be written as the sum of the two major contributions of the cooling: the sensible heat and the evaporation of the droplet. Finally, a high speed shadow imagery technique is presented. It has been developped in order to study the dynamic aspect of the droplet impact. This technique can determine several dynamic parameters such as the droplet speed and diameter, or other parameter regarding the type of impact encountered