Avec la performance thermique croissante des bâtiments, les codes de simulation utilisés en conception requièrent des données de plus en plus précises sur les matériaux de construction. De plus, l’utilisation de matériaux biosourcés qui sont hygroscopiques (leur teneur en eau s’équilibre avec l’air humide ambiant) est en pleine expansion. Leur conductivité thermique et leur diffusivité massique doivent ainsi être caractérisées précisément. Un facteur essentiel affectant ces propriétés est la microstructure des matériaux. Ce travail de thèse propose de prédire les propriétés macroscopiques d’épicéa et de panneaux de fibres de bois (matériaux hétérogènes et anisotropes) à partir de leur morphologie réelle 3D. Celle-ci est obtenue par micro-tomographie synchrotron aux rayons X, outil très performant pour caractériser la structure interne d’un matériau de façon non destructive. Un traitement d’images permet de segmenter les phases solide et gazeuse. La méthode numérique choisie pour modéliser la diffusion de chaleur et de masse est la méthode Lattice Boltzmann car elle est simple à implémenter et à paralléliser et qu’elle peut facilement traiter des morphologies complexes. Les conductivités thermiques et diffusivités massiques équivalentes sont calculées dans trois directions orthogonales pour chaque matériau. Les résultats mettent en évidence l’influence de la structure interne et la forte anisotropie des matériaux étudiés (rapport 2 entre les directions tangentielle et longitudinale du bois en thermique et 30 en massique). La conductivité thermique transversale du panneau léger est de 0,04 W m−1 K−1. / As thermal performance of buildings is increasing, the simulation codes used during design require more accurate construction material data. Moreover, the use of bio-based materials which are hygroscopic (their moisture content balances with the ambient moist air) is booming. Their thermal conductivity and mass diffusivity must therefore be accurately characterized. A key factor affecting these properties is the microstructure of the materials. This work is dedicated to the prediction of macroscopic properties of spruce and fibreboards (heterogeneous and anisotropic materials) from their real 3D morphology. This is obtained by synchrotron X-ray microtomography, a powerful and nondestructive technique to characterize the internal structure of materials. Image processing allows the segmentation of the solid and gaseous phases. To model heat and mass diffusion, we choose the Lattice Boltzmann method because of its simple numerical development, suitability for parallel computing and easy processing of complex morphologies. The equivalent thermal conductivity and mass diffusivity are calculated in three orthogonal directions for each material. The results highlight the influence of the internal structure and the strong anisotropy of the materials studied (ratio of 2 between tangential and longitudinal directions of wood for heat diffusion and of 30 for mass diffusion). The transverse thermal conductivity of the lightweight board is about 0,04 W m−1 K−1.

A avaliação do risco a contaminação e a escolha de técnicas de remediação de poluentes em aquíferos fraturados depende da quantificação dos fenômenos envolvidos no transporte de solutos. A geometria da fratura, usualmente caracterizada pela abertura, é o principal parâmetro que indiretamente controla o transporte nos aquíferos fraturados. A simplificação mais comum desse problema é assumir que as fraturas são um par de placas planas e paralelas, isto é, com uma abertura constante. No entanto, por causa do limitado número de trabalhos experimentais, não está esclarecida a adequabilidade do uso de uma abertura constante para simular o transporte conservativo em fraturas do Aquífero Serra Geral (ASG), Brasil. O objetivo deste trabalho é avaliar a influência da abertura de uma fratura natural do Aquífero Serra Geral sob o transporte conservativo de solutos. Uma amostra natural de basalto fraturado foi usada em um experimento hidráulico e de transporte de um traçador conservativo (escala de laboratório). O campo de abertura foi medido usando a técnica avançada, de alta resolução e tridimensional, chamada microtomografia computadorizada de raios-X. A concentração de traçador medida foi utilizada para validar uma solução analítica unidimensional da Equação de Advecção-dispersão (ADE). O desemprenho do ajuste da ADE às curvas de passagem experimentais foi avaliado para quatro diferentes tipos de aberturas constantes. Os resultados mostraram que o escoamento de água e o transporte de contaminantes pode ocorrer através de fraturas micrométricas, ocasionando, eventualmente, a contaminação do ASG. A abertura de balanço de massa é a única que pode ser chamada propriamente de \"abertura equivalente\". O uso de aberturas constantes na ADE não permitiu representar completamente o formato das curvas de passagem porque o campo de velocidade não é uniforme e intrinsicamente bidimensional. Portanto, na simulação do transporte deve-se incorporar a heterogeneidade da abertura da fratura. / The contamination risk assessment and the choice of suitable cleanup techniques for pollutants in fractured rock depends on the quantification of the transport phenomena. Fracture geometry often described by the apertures is the major parameter that controls indirectly solute transport in fractured rock. The simplest approach is describing fractures as a pair of smooth parallel plates with constant aperture. However, there is a lack of information about the suitability for using a constant aperture for the conservative solute transport prediction in a single fracture of Serra Geral Aquifer (SGA), Brazil. The aim of this work is to evaluate the effect of aperture variability in a natural single rough-walled fracture of Serra Geral Aquifer on conservative solute transport. A natural core of fractured basalt was used for a hydraulic and tracer tests (laboratory scale). The aperture field was measured using the advanced, high-resolution and tridimensional technique X-ray computed tomography. The measured tracer concentration was validated by means of an analytical solution of the Advection-dispersion Equation (ADE). The ADE fit performance was measured against experimental breakthrough curves for four distinct kind of constant apertures. It was found that water flow and solute transport can take place through micrometric fractures, eventually leading the SGA contamination. Results show that the mass balance aperture is the only appropriate \"equivalent aperture\" for describing solute transport in a single rough-walled fracture. The results showed that ADE is not appropriate for modeling the complete behavior of experimental breakthrough curves because of the dimensional non-uniform velocity field. Therefore, the aperture heterogeneity must be considered in solute transport simulation.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / O objetivo principal desse trabalho foi utilizar métodos não destrutivos (END), como a microtomografia com Raio X e técnicas de obtenção e processamento de imagens, para obtenção da porosidade do concreto. Foram utilizados dois métodos. Em um método as imagens foram obtidas por meio de microtomografia por Raio X e no outro foi utilizado um escâner comercial para obtenção das imagens. Essas imagens foram processadas por meio de técnicas de processamento de pixel e morfologia matemática. Os resultados obtidos para a porosidade foram comparados com resultado obtido por meio do método proposto pela NBR 9778 (2005) (Absorção de água, índice de vazios e massa específica em argamassa e concreto endurecido). As imagens microtomográficas das amostras de concreto foram obtidas num sistema Skyscan 1172 com 256 tons de cinza, ajustadas em contraste, binarizadas e filtradas. No outro método foi utilizado um Escâner Comercial com resolução de 2400 dpi para adquirir as imagens, sendo também utilizadas técnicas de processamento de pixel e morfologia matemática para processá-las. Os resultados dos valores da porosidade mostraram compatibilidade entre os dois métodos apresentados e o método proposto pela NBR 9778 (2005). Observou-se que os resultados obtidos por microtomografia foram mais confiáveis, mas o método utilizando o escâner comercial se apresentou como um método aceitável por seus resultados e principalmente por seu baixo custo e facilidade de operação. / The main goal of this research was to use non-destructive methods (ND), like the X Ray microtomography and techniques to acquire and process images, to obtain the concrete porosity. There were presented two methods. In one of the methods the images were acquired through X Ray microtomography and in the other method there were used the commercial scanner to acquire the images. Those images were processed using techniques of pixel processing and mathematical morphology. The results to the porosity were compared with the result obtained through the method proposed by NBR 9778 (2005) (Absorção de água, índice de vazios e massa específica em argamassa e concreto endurecido). The microtomographed images of the concrete samples were obtained using a Skyskan 1172 system with 256 gray levels, adjusted in contrast, binarized and filtered. In the other method there were used a commercial scanner with 2400 dpi of resolution to acquire the images, being also used techniques of pixel processing and mathematical morphology to process them. The results have shown compatibility between the two presented methods and the method presented by NBR 9778 (2005). It was observed that the results obtained by microtomography were more reliable, but the method using the scanner is presented as an acceptable method for their results and especially for its low cost and ease of operation.

A avaliação do risco a contaminação e a escolha de técnicas de remediação de poluentes em aquíferos fraturados depende da quantificação dos fenômenos envolvidos no transporte de solutos. A geometria da fratura, usualmente caracterizada pela abertura, é o principal parâmetro que indiretamente controla o transporte nos aquíferos fraturados. A simplificação mais comum desse problema é assumir que as fraturas são um par de placas planas e paralelas, isto é, com uma abertura constante. No entanto, por causa do limitado número de trabalhos experimentais, não está esclarecida a adequabilidade do uso de uma abertura constante para simular o transporte conservativo em fraturas do Aquífero Serra Geral (ASG), Brasil. O objetivo deste trabalho é avaliar a influência da abertura de uma fratura natural do Aquífero Serra Geral sob o transporte conservativo de solutos. Uma amostra natural de basalto fraturado foi usada em um experimento hidráulico e de transporte de um traçador conservativo (escala de laboratório). O campo de abertura foi medido usando a técnica avançada, de alta resolução e tridimensional, chamada microtomografia computadorizada de raios-X. A concentração de traçador medida foi utilizada para validar uma solução analítica unidimensional da Equação de Advecção-dispersão (ADE). O desemprenho do ajuste da ADE às curvas de passagem experimentais foi avaliado para quatro diferentes tipos de aberturas constantes. Os resultados mostraram que o escoamento de água e o transporte de contaminantes pode ocorrer através de fraturas micrométricas, ocasionando, eventualmente, a contaminação do ASG. A abertura de balanço de massa é a única que pode ser chamada propriamente de \"abertura equivalente\". O uso de aberturas constantes na ADE não permitiu representar completamente o formato das curvas de passagem porque o campo de velocidade não é uniforme e intrinsicamente bidimensional. Portanto, na simulação do transporte deve-se incorporar a heterogeneidade da abertura da fratura. / The contamination risk assessment and the choice of suitable cleanup techniques for pollutants in fractured rock depends on the quantification of the transport phenomena. Fracture geometry often described by the apertures is the major parameter that controls indirectly solute transport in fractured rock. The simplest approach is describing fractures as a pair of smooth parallel plates with constant aperture. However, there is a lack of information about the suitability for using a constant aperture for the conservative solute transport prediction in a single fracture of Serra Geral Aquifer (SGA), Brazil. The aim of this work is to evaluate the effect of aperture variability in a natural single rough-walled fracture of Serra Geral Aquifer on conservative solute transport. A natural core of fractured basalt was used for a hydraulic and tracer tests (laboratory scale). The aperture field was measured using the advanced, high-resolution and tridimensional technique X-ray computed tomography. The measured tracer concentration was validated by means of an analytical solution of the Advection-dispersion Equation (ADE). The ADE fit performance was measured against experimental breakthrough curves for four distinct kind of constant apertures. It was found that water flow and solute transport can take place through micrometric fractures, eventually leading the SGA contamination. Results show that the mass balance aperture is the only appropriate \"equivalent aperture\" for describing solute transport in a single rough-walled fracture. The results showed that ADE is not appropriate for modeling the complete behavior of experimental breakthrough curves because of the dimensional non-uniform velocity field. Therefore, the aperture heterogeneity must be considered in solute transport simulation.

Os bisfosfonatos (BF) são amplamente utilizados no tratamento de doenças osteolíticas como metástases ósseas e osteoporose. A osteonecrose dos maxilares associada ao uso de BF (OMAB) é caracterizada pela presença de osso exposto ou que pode ser sondado através de uma fístula que persiste por mais de oito semanas em pacientes com história de terapia de BF e sem história de radioterapia na região de cabeça e pescoço e/ou sem doença metastática nos maxilares. A incidência de OMAB aumenta com a potência, duração do tratamento e dose de BF recebida. Até o presente momento, a fisiopatologia da OMAB não está clara, dificultando a prevenção e o tratamento. O objetivo deste estudo foi avaliar o efeito da administração de altas doses Ácido Zoledrônico (AZ) por período prolongado no osso esponjoso da mandíbula e da metáfise proximal do fêmur de ratos Wistar. Para relacionar as descobertas à fisiopatologia da OMAB, o regime de administração de BF de um modelo animal relevante desta lesão foi reproduzido. Seis animais receberam AZ (0,6 mg / kg) e seis receberam solução salina no mesmo volume (Controles). Os compostos foram administrados por via intraperitoneal em cinco doses a cada 28 dias. A eutanásia dos animais ocorreu após 150 dias de início da terapia. As hemimandíbulas e fêmures direitos foram escaneados usando Micro-tomografia computadorizada (Micro-CT) de alta resolução (14 m). Para a primeira análise realizada neste estudo, os dados morfométricos do osso esponjoso foram calculados na região do segundo e primeiro molar na mandíbula e na metáfise do fêmur usando CTAnalyzer (Bruker, Bélgica). Para a segunda análise, cinco amostras de hemimandíbulas de cada grupo foram cortadas em lâminas histológicas (5 m) e coradas com Hematoxilina e Eosina. Para comparar os parâmetros morfométricos na Micro-CT e histologia, as imagens de Micro-CT foram espacialmente alinhadas à histologia. Os dados morfométricos do osso alveolar foram calculados usando o software CTAnalyzer (Bruker, Bélgica) na região entre as raízes mesial e distal do primeiro molar. A densidade da área vascular (área vascular/área total; VA/TA) e os dados histomorfométricos ósseos foram estimados usando Axiovision na mesma região (entre as raízes mesial e distal do primeiro molar). Foi adotada significância estatística de 5% ( = 0,05). Os animais tratados com AZ apresentaram aumento significativo na porcentagem de volume ósseo (p <0,05) com trabéculas mais espessas, osso mais compacto com menor separação trabecular na mandíbula e no fêmur. Na mandíbula, o aumento da densidade óssea e diminuição da separação trabecular foram fortemente correlacionados com a diminuição da área vascular observada no grupo AZ (p <0,05). Em conclusão, o tratamento de longa duração com altas doses de AZ foi significativamente associado ao aumento na densidade óssea e à diminuição dos espaços medulares, canais nutritivos e vasculatura do osso alveolar. A análise com Micro-CT revelou alterações semelhantes na estrutura óssea tanto na mandíbula quanto no fêmur do grupo AZ. / Bisphosphonates (BFs) are widely used in the treatment of osteolytic diseases such as bone metastases and osteoporosis. The osteonecrosis of the jaws related to BF (ONB) is characterized by the presence of exposed bone or bone that can be probed through a fistula that persists for more than eight weeks in patients with a history of BF therapy and without history of head and neck radiotherapy and / or without metastatic disease in the jaws. The incidence of ONB increases with potency, duration of treatment and dose of BF received. Thus far, the pathophysiology of ONB is unclear, hampering prevention and treatment. The aim of this study was to objectively assess the effect of long-term high-dose Zoledronic Acid (ZA) on cancellous bone in the jaw and femur of Wistar rats. In order to link our findings to the physiopathology of ONB, the therapeutic regiment of a relevant ONB animal model was reproduced. Twelve Wistar rats were randomly divided in two groups: six received Zoledronic acid (ZA; 0.6 mg / kg) and six (Controls) received saline solution in the same volume. The compounds were administrated intraperitoneally in five doses each 28 days. The rats were killed after 150 days of the therapy onset. Mandibles and femurs were scanned using a high-resolution (14m) micro-computerized tomography (Micro-CT). For the first analysis carried in this study, cancellous bone morphometric data were calculates in the region of the second and first molar in the mandible and in the proximal femur using CTAnalyzer (Bruker, Belgium). For the second analysis five samples were cut into histological slices (5m) and stained with Hematoxylin and Eosin. In order to compare the same morphological structures in Micro-CT and histology, the Micro-CT images were aligned to histology. Alveolar bone morphometric data (Micro-CT) was calculated using CTAnalyzer (Bruker, Belgium) in the region between the mesial and distal roots of the first molar. Blood vessels density and bone histomorphometric data were calculated using Axiovision (Carl Zeiss, Germany) in the same region used for Micro-CT evaluation. Statistical significance of 5% (=0.05) was adopted. ZA treated rats presented significant increase in the percentage of bone volume (p<0.05) with thicker trabeculae and more compact bone with smaller marrow spaces in the mandible and femur. In the mandible, the increase in bone density and decrease of marrow spaces size was strongly correlated with the decrease in the vascular area noticed in the ZA group (p<0.05). In conclusion, long-term high-dose ZA treatment was significant associated with the increase of bone density and the diminution of medullary spaces and nutritive canals size as well as decrease in vascularity of the alveolar bone. Micro-CT investigation showed similar changes in bone structure in the mandible and femur in the ZA group.

The study of internal structure of materials has always been an essential issue in a variety of application fields, from the medical radiology to the materials science. X-ray computed microtomography (with both conventional and synchrotron radiation sources) has a great potential for these purposes because its three-dimensional and non destructive nature as well as the fact that it does not require any sample preparation and it allows to study samples under stress or after consecutive treatments. The recent developments of new X-ray sources with innovative imaging techniques, as well as novel high resolution detectors, allow moving forward the maximum achievable resolution of this technique to a few micrometers or even less. This contributed to increase its application in biomedical purposes, but also to raise the need for quantitative analysis of the reconstructed data. Indeed in most of the cases a quantitative characterization of the samples microstructures is needed to better understand their physical and chemical behavior, the effects of manufacturing process or the response to stress. Dedicated software packages have been developed to perform a geometrical and morphological characterization of the samples texture and to evaluate some typical parameters commonly used to classify porous media such as porosity, cell size distribution, connectivity and anisotropy. In this work two case studies have been considered for the application of a quantitative analysis approach to microtomography datasets: the first concerns the characterization of bone ingrowth within tissue engineering scaffolds, while the second is related to the extraction of morphological descriptors for the architecture of human skull bones. It will be shown how suitable image processing and analysis techniques are able to effectively quantify significant parameters such as the trabecular thickness of the skull bones as well as the porosity and the degree of connectivity of bone tissue engineering scaffolds. Similar quantitative analysis methods applied to microtomography images have to be considered as an effective methodology for a comprehensive characterization of other biomedical samples.

The use of Computerised microtomography (CμT) in biomedical research is well established, with most applications developed at synchrotron facilities. The possibility to non-invasively monitor morphological changes in biological samples, makes it an attractive technique in biomedicine. However, high absorbed doses and long examination times are a disadvantage that limits the possibilities of performing longitudinal examinations. The aim of this work was to optimise CmT using conventional X-ray tubes for applications in non-destructive material testing and for skeleton research in small animals (rat). A calculational model of the imaging system was developed and used to optimise the relation between image quality, expressed as the signal-to-noise ratio (SNR) in detecting a contrasting detail, and imaging time in material testing. The model was modified to optimise the relation between the SNR in detecting a trabecular detail in cancelleous bone and the mean absorbed dose in spongiosa and skin for (rat) tibia and femur. Gastrectomized Sprague-Dawley rats were used to initiate osteoporotic changes. In order to detect differences in between gastrectomized rats and controls, spatial resolutions of 150 mm or better were needed. The minimum absorbed doses in femur spongiosa at SNR = 5 were 1mGy - 700 mGy at spatial resolutions from 100 mm to10 mm. In femur skin, the corresponding minimum absorbed doses were 2 mGy - 2000 mGy. Corresponding values for tibia were 0.3 mGy - 300 mGy for both spongiosa and skin (spatial resolution of 100 mm to10 mm). Taking 0.5 Gy as the tolerance limit for the spongiosa dose, longitudinal studies with six repeated examinations will be possible at a spatial resolution of 25 mm in femur and 17 examinations in tibia.

No description available.

Cette thèse s’intéresse à la conception de nouveaux matériaux compositesferroélectriques/diélectriques aux propriétés accordables en tension. Des granules diélectriques(MgO, TiO2) obtenues par atomisation sont dispersées dans une matrice ferroélectrique (Ba1-xSrxTiO3). Le mélange est ensuite densifié par Spark Plasma Sintering (SPS). Une approcheoriginale est développée afin de déterminer les paramètres reliant la microstructure aux propriétésphysiques pour chacune des étapes de la boucle d’optimisation élaboration - caractérisation -modélisation. La stratégie adoptée s’appuie sur i) l’utilisation des propriétés spécifiques du frittageSPS qui offre une gestion précise des interfaces entre les différents composés. Cette méthode nonconventionnellea permis l’élaboration de composites ferroélectriques architecturés, constituésd’inclusions diélectriques de géométries contrôlées ; ii) les potentialités offertes par lamicrotomographie X comme moyen de description de la microstructure 3D des matériauxcomposites aux étapes clés de leur conception. Couplée à de puissants outils de traitements desimages elle permet d’extraire les éléments pertinents guidant l’optimisation et la compréhension despropriétés finales ; iii) le développement d’un modèle numérique 3D de l’accordabilité appliquédirectement à la géométrie réelle des matériaux extraite des images de microtomographie. Cetteétape est essentielle pour comprendre l’origine de la redistribution du champ électrique entre lesphases. Les résultats numériques obtenus sont directement confrontés aux mesuresexpérimentales. / This thesis is focused on the conception of new tunable ferroelectric/dielectric compositematerials. Dielectric granules (MgO, TiO2) obtained by spray-drying are dispersed in a ferroelectricmatrix (Ba1-xSrxTiO3). Mixing powder is then densified by Spark Plasma Sintering (SPS). An originalapproach is developed in order to determine parameters linking the microstructure to the physicalproperties for each step of the elaboration - characterization - modelling optimization procedure.The adopted strategy is based on i) specific SPS properties which provide an accurate control of theinterfaces between each components; ii) potentialities offered by X-ray microtomography to describethe internal 3D microstructure of the composite materials during the key steps of their elaboration.Associated with powerful image processing tools, it allows to obtain relevant elements guiding theoptimization and understanding of the final properties; iii) the development of a 3D numerical modelof tunability applied directly to the real geometry which has been extracted from 3Dmicrotomography images. This step is essential to understand the origin of the redistribution of theelectric field between the different phases. Numerical results are directly compared to experimentalmeasurements.

A microtomografia computadorizada (uCT) é uma técnica de ensaio não destrutivo, frequentemente utilizada no estudo da estrutura interna de ossos, com uma resolução espacial da ordem de mícrons. Neste trabalho, seis pares de amostras ósseas (fêmur de rato) foram estudados através da uCT. Os ensaios foram conduzidos na presença ou não de filtros de alumínio (espessura de 0,25; 0,50 e 0,75 mm), utilizando-se três níveis de resolução (33,3; 15,0 e 9,5 um). Os parâmetros de arquitetura óssea BS (área óssea da amostra), BV (volume ósseo da amostra), TS (área superficial da amostra), TV (volume da amostra), BV/TV (razão entre o volume ósseo e o volume da amostra), BS/BV (razão entre a área óssea da amostra e o volume ósseo da amostra), Tb.N (densidade trabecular), Tb.Th (espaçamento entre as trabéculas), Tb.Sp (separação trabecular), conectividade e anisotropia foram determinados através das análises em duas (2D) e/ou três (3D) dimensões. A comparação entre os valores dos parâmetros obtidos através dessas análises foi realizada através do teste t pareado e da correlação de Pearson. Com base nos resultados, foi possível determinar a influência da resolução da imagem na qualidade dos parâmetros da arquitetura óssea obtidos através das análises 2D e/ou 3D. Os dados mostram que a presença de filtro de alumínio também afeta a qualidade desses parâmetros. Assim, os melhores resultados são obtidos com resolução máxima e filtro de alumínio com espessura de 0,25 ou 0,50 mm. / X-Ray Computed Microtomography (uCT) is a nondestructive technique used to study the internal structure of bones with a spatial resolution of the order of microns. In this study, six pairs of bone samples (femur mouse) were studied by uCT. The tests were conducted in the absence or presence of aluminum filters (thickness of 0.25, 0.50 and 0.75 mm), using three different resolution levels: 33.3, 15.0 and 9.5 um. The bone architecture parameters BS (surface area of the trabecular bone), BV (bone volume of the sample), TS (surface area of the sample), TV (sample volume), BV/TV (bone volume fraction), BS/BV (ratio bone surface and volume), Tb.N (trabecular density), Tb.Th (trabecular spacing), Tb.Sp (trabecular separation), connectivity and anisotropy were determined by 2D and/or 3D analysis. The comparison between the values of the parameters obtained in these analysis was performed using the t test and Pearson correlation. Based on the results it was possible to determine the influence of image resolution on the quality of the bone architecture parameters obtained in the 2D and/or 3D analysis. The data also show that the presence of aluminum filter affects the quality of these parameters. Thus, the best results are obtained with maximum resolution and aluminum filter with a thickness of 0.25 or 0.50 mm.