Orientador: Guilherme Monteiro Tosoni / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-21T22:12:50Z (GMT). No. of bitstreams: 1 Oliveira_MatheusLimade_D.pdf: 24389100 bytes, checksum: b2e18d1167061c00f8285f26e1f8d746 (MD5) Previous issue date: 2013 / Resumo: O objetivo deste estudo foi avaliar a influência da região anatômica e do tamanho do FOV (field of view) nos valores de cinza em imagens de tomografia computadorizada de feixe cônico (TCFC). Soluções homogêneas de fosfato de potássio dibásico (K2HPO4) foram preparadas em sete diferentes concentrações e armazenadas separadamente em tubos de polipropileno. Um phantom de uma cabeça humana teve seis dentes extraídos - um incisivo central um primeiro prémolar e um primeiro molar da maxila e da mandíbula - e substituídos por esses tubos, que foram escaneados separadamente pelos aparelhos NewTom 3G, NewTom 5G e 3D Accuitomo 170, sob diferentes tamanhos de FOV. Em cortes axiais, valores médios de cinza foram obtidos em cinco níveis diferentes dentro de cada tubo de polipropileno e a média foi calculada. Para cada aparelho, análise de regressão linear avaliou a relação entre os valores médios de cinza e a concentração de K2HPO4 em seis regiões anatômicas, sob os diferentes FOVs. Coeficiente de determinação (R2) foi calculado. Nos três aparelhos, a correlação linear entre os valores de cinza e as concentrações de K2HPO4 variou entre as regiões anatômicas e os tamanhos de FOV (0,93 < R2 < 0,99). Desse modo, pode se concluir que a relação entre os valores de cinza em imagens de TCFC e a densidade do objeto não é uniforme por todo o arco dentário e é influenciada pelo tamanho do FOV nos três aparelhos de TCFC testados. A comparação desses valores obtidos em diferentes regiões anatômicas e com diferentes tamanhos de FOV não é confiável / Abstract: The aim of this study was to evaluate the influence of anatomical location and FOV (field of view) size in CBCT numbers. Homogeneous solutions of dipotassium phosphate (K2HPO4) were prepared at seven different concentrations and stored separately in polypropylene tubes. Six teeth were extracted from a human head phantom - the upper and lower central incisors, first premolars and first molars - and replaced by the tubes, which were scanned separately by NewTom 3G, NewTom 5G and 3D Accuitomo 170 under different FOV sizes. In axial sections, CBCT numbers were obtained at five levels within each polypropylene tube, and the average was calculated. For each CBCT unit, linear regression analysis evaluated the relationship between CBCT numbers and the concentration of K2HPO4 in six anatomical regions, under different FOVs. Coefficient of determination (R2) was calculated. Linear correlation between CBCT numbers and concentrations of K2HPO4 ranged between anatomical regions and FOV sizes (0.93 < R2 <0.99). Thus, it can be concluded that the relationship between CBCT numbers and object density is not uniform throughout the dental arch, and is influenced by the FOV size on the three CBCT units tested in this study. The comparison of CBCT numbers from different anatomical regions and with different FOV sizes is unreliable / Doutorado / Radiologia Odontologica / Doutor em Radiologia Odontológica

La fabrication additive est un procédé offrant de nouvelles opportunités aux industriels pour fabriquer des pièces complexes, sans outillage spécifique et en optimisant la matière utilisée.Cette thèse présente les propriétés mécaniques de pièces réalisées par fabrication additive et l’analyse des mécanismes d’endommagement associés, en ayant comme référence les propriétés mécaniques des procédés de fonderie et de corroyage. Ce type d’analyse est indispensable pour l’industrialisation du procédé.Les propriétés en traction et en fatigue, sur des éprouvettes en titane Ti-6Al-4V et en aluminium AlSi7Mg0,6, ont été mesurées. Les effets du procédé de fabrication, de la direction de fabrication, du post-usinage et des post-traitements thermiques ont été comparés. Les propriétés sont au moins au niveau de la fonderie.Ces résultats ont été analysés en corrélation avec les microstructures et les faciès de rupture, afin de dégager des mécanismes d’endommagement. Les critères permettant de mesurer la criticité des défauts ont été définis.Certaines de ces hypothèses ont pu être vérifiées grâce à des essais de traction in situ au micro tomographe. / Additive manufacturing offers new opportunities for industries to manufacture complex parts with no additional tooling and better optimization of the material used.This thesis is about the analysis of the mechanical properties and the damaging mechanisms of parts produced by additive manufacturing, using mechanical properties of casted and wrought parts as reference. This type of analysis is necessary in order to industrialize the process.The tensile and fatigue properties on Titanium Ti-6Al-4V and Aluminium AlSi7Mg0,6 were measured. The effects of the process, the manufacturing direction, the post-machining and the post-heat treatments were compared. Properties are at least at the level of casting.A correlation of these results with microstructures and fracture surfaces was made in order to extract the damaging mechanisms. A method to measure the criticity of the defects in a part was defined. Some of these hypotheses were verified using microtomographic in situ tensile tests.

Le travail présenté dans cette thèse vise à apporter une compréhension fine des couplages hydromécaniques et plus particulièrement du phénomène d'effondrement capillaire. L'utilisation de matériaux granulaires modèles observés à petites échelles grâce au microtomographe à rayons X constitue le point de départ de cette étude. Les résultats portent dans un premier temps sur la capacité à reproduire et observer le phénomène d'effondrement capillaire à l'échelle de l'éprouvette, appelée aussi échelle macroscopique. Une des premières problématiques importantes de ce projet a donc porté sur la reconstitution d'éprouvettes suffisamment lâches permettant d'observer le phénomène effondrement. Le potentiel d'effondrement, alors mesuré au simple œdomètre sur ces éprouvettes reconstituées, décroit avec la charge mécanique appliquée. En contrôlant le volume d'eau au cours de l'imbibition, les éprouvettes sont sujettes à une succession d'incréments de déformation rapides et ceci quelle que soit la dynamique de mouillage. En parallèle, l'utilisation de la technique d'analyse non destructive par microtomographie aux rayons X nous a permis de quantifier à une échelle mésoscopique (échelle de quelques grains), l'évolution de matériaux granulaires sous chargement hydrique et mécanique. Cela a été possible par l'utilisation de la technique de corrélation d'images numériques (DIC) associée à des outils d'analyse adaptés aux matériaux non saturés. Ces outils révèlent que l'hétérogénéité locale des déformations et des teneurs en eau augmente au cours de l'imbibition principalement à cause de l'effet de la gravité sur la répartition de l'eau dans l'éprouvette. L'hétérogénéité initiale des éprouvettes induite par la méthode de préparation est aussi identifiée. Cependant, malgré la présence de ces hétérogénéités, nous montrons que les mesures réalisées à l'échelle de l'éprouvette restent représentatives du comportement mésoscopique du matériau au cours de l'effondrement / This thesis deals with hydromechanical couplings in soils and more particularly focusing on the capillary collapse phenomenon. Although thoroughly studied at macroscopic scale in fine soils, the mechanisms governing capillary collapse in granular soils have been less observed.At first, the results concern the capacity to reproduce and to observe the phenomenon of capillary collapse at the scale of the specimen, called also the macroscopic scale.Thus, one of the first important objectives of this project concerned the preparation method of the specimens, which have to be loose enough to observe this phenomenon. The collapse potential, determined here by the one-dimensional collapse test, decreases with the mechanical stress. Moreover, when the quantity of water is controlled, incremental strains of specimens arise whatever the imbibition dynamic.To complement existing data, an experimental program was carried out using X-ray computed tomography (X-ray CT), a relevant tool to obtain 3D informations at grain scale. In combination with Volumetric Digital Image Correlation (V-DIC), X-ray CT also makes it possible to get information at a mesoscopic scale, at which the use of continuum mechanics still remains relevant. In this work, both microscopic and mesoscopic analyses have been carried out on a partially saturated sand subjected to gradual controlled imbibition in an oedometric cell.Local heterogeneities of strains and water contents appear during the imbibition, which are principally explained by the effect of gravity and by an inhomogeneity of the initial density.However, in spite of the existence of those localisations, by comparing the analyses at the mesoscopic and at the macroscopic scale, we show that measurements performed at the scale of the specimen are representative of the local behaviour of the material

L’objectif de cette thèse est de réaliser un agent de contraste vasculaire pour tomodensitométrie utilisable en préclinique. En collaboration avec le laboratoire de biogalénique de Strasbourg, ce travail a permis d’obtenir des nano-émulsions iodées produites par diffusion spontanée de surfactif et des nanoparticules iodées produites par ”émulsion - diffusion de solvant”, comme agent de contraste vasculaire. Ces émulsions et particules polymériques présentent en effet, un temps de rémanence vasculaire de plusieurs heures, un pouvoir contrastant suffisant pour un usage en tomodensitométrie (compris entre 170 et 400 HU), la possibilité de les administrer par intraveineuse et une stabilité de plusieurs mois. Les nano-émulsions, notamment celles produites à partir de Lipiodol®, sont les plus prometteuses comme agents de contraste vasculaire de par leur forte radiopacité (475 ± 30 HU) et leur rémanence vasculaire (T1/2 of 4.1 ± 1.10 h). Les nanoparticules iodées à base de PCL présentent un pouvoir contrastant inférieur (168 ± 13 HU) mais elles sont connus pour leur capacité à modifier la libération du principe actif encapsulé. De ce fait même si les agents de contraste de nature lipidique ou ceux inorganiques sont plus performant, elles restent intéressantes pour une visualisation rapide de la distribution du principe actif dans l’organisme. Cette thèse par ailleurs, apporte plusieurs éléments pour la compréhension de la formulation des nano-émulsions obtenues par diffusion spontanée de surfactif et celle des nanoparticules produites par ”émulsion - diffusion de solvant”. Concernant les nano-émulsions, l’influence de l’iodation des huiles et du surfactif a été étudiée autant sur le plan pharmacotechnique que ceux toxicologique et pharmacocinétique. Concernant les nanoparticules à base de PCL, nous avons montré que l’impact du type d’huile et de l’iodation, des polymères PCL et PCL-mPEG et de diverses méthodes de concentration sur la formulation / The aim of this thesis is to formulate a blood pool contrast agent for preclinical X-ray imaging application. In collaboration with the galenic laboratory of Strasbourg, this work has allowed to obtain iodinated nano-emulsions produced by spontaneous diffusion of surfactant and nano-particles produced by iodine ”emulsion - solvent diffusion” as blood pool contrast agent. These emulsions and polymer particles present indeed a vascular persistence of several hours, a sufficient contrast to be use in computed tomography (between 170 and 400 HU), the ability to be administered intravenous and stability of several months. Nano-emulsions, including those produced from Lipiodol®, are the most promising as blood pool contrast media by their high radiopacity (475 ± 30 HU) and vascular persistence (T1/2 of 4.1 ± 1.10 h). Iodinated nano-particles of PCL have a lower X-ray attenuation (168 ± 13 HU), but they are known for their control release of the encapsulated substances. Therefore even if inorganic or lipidic contrast agents show a better contrast, they remain attractive for rapid visualization of the co-encapsulated substance distribution in the body. This thesis also introduced several features for understanding the formulation of nano-emulsions obtained by spontaneous diffusion of surfactant and the nano-particles produced by ”emulsion - solvent diffusion.”

Orientador: Osvair Vidal Trevisan / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-27T00:58:52Z (GMT). No. of bitstreams: 1 VidalVargas_JanethAlina_D.pdf: 6980631 bytes, checksum: 2e858ba97bc5f6f4bb3b1a075776555f (MD5) Previous issue date: 2015 / Resumo: O conhecimento dos fenômenos físicos envolvidos no transporte de fluidos no meio poroso é muito importante para o projeto e o sucesso dos processos de recuperação melhorada de petróleo. O deslocamento miscível é um dos métodos mais eficientes de recuperação melhorada de petróleo. O parâmetro mais relevante na eficiência do deslocamento miscível é a dispersão, que controla a evolução da zona de mistura dos dois fluidos e a propagação do fluido injetado. Neste trabalho é desenvolvido e avaliado um modelo matemático para o deslocamento miscível 1-D em meios heterogêneos. O modelo, referido como modelo de concentração total (MCT) é desenvolvido com base na equação de convecção-dispersão (ECD) considerando a interação entre a rocha e os fluidos. Os parâmetros fenomenológicos envolvidos no MCT são o coeficiente de dispersão, o coeficiente de transferência de massa, a porosidade efetiva do meio poroso no momento de deslocamento e a fração de soluto que é depositada ou retirada do meio poroso. Estes parâmetros podem ser determinados por meio de ajustes multiparâmétricos do modelo aos dados obtidos em laboratório. Para avaliar a aplicação do modelo MCT foram realizados dois experimentos A e B, cada um formado por 4 e 5 testes de deslocamento respectivamente. Os testes de deslocamento utilizaram duas salmouras e foram realizados empregando-se uma rocha carbonática. A evolução das concentrações ao longo do meio poroso foi medida por Tomografia Computadorizada de Raios-X (TC). A grande quantidade de dados dos perfis de concentração determinados a partir das imagens da TC do Experimento A foi analisada e ajustada utilizando-se o modelo MCT por meio do método metaheurístico de recozimento simulado (Simulated Annealing, SA). O procedimento de ajuste global, considerando todas as curvas do histórico de concentração, foi utilizado para a determinação dos parâmetros governantes dos fenômenos envolvidos. A quantidade de dados utilizados e a robustez do método permitiu um ajuste muito bom do modelo aos dados experimentais. Determinou-se um coeficiente de dispersão de aproximadamente 0,01cm2/s para vazão de 1 cm3/min e 0,05 cm2/s para vazão de 5 cm3/min. Foram avaliados também os parâmetros de transferência de massa e interação do fluido com o meio poroso. O Experimento B foi realizado com a finalidade de comprovar a deposição de soluto enquanto o fluido se deslocava através da amostra de rocha. No modelo MCT, este fenômeno foi quantificado por meio do parâmetro fr. Os perfis de concentração do Experimento B foram medidos na entrada, ao longo da amostra (rocha) e na saída. A partir desses perfis, foi realizado um balanço de massa para avaliar a fração de deposição de soluto (fr) formulada e determinada a partir do MCT. Os valores de fr obtidos foram de 0,2 a 0,4, que são valores coerentes com os resultados obtidos com o modelo MCT / Abstract: The knowledge of the physical phenomena involved in fluid transport in porous medium is very important for the design and successful execution of oil enhanced recovery processes. Miscible displacement is one of the most efficient recovery methods. Dispersion is a key phenomenon in miscible displacement. It controls the evolution of the mixing zone of both fluids and the propagation of injected fluid. The present study focuses on the development and evaluation of a mathematical model for the 1-D miscible and active displacement in an intrinsically heterogeneous porous media. The model, referred to as total concentration model (TCM), is developed based on the convection-dispersion equation (CDE) considering the interaction between rock and fluids. The phenomenological parameters involved in TCM are the dispersion coefficient, the mass transfer coefficient, the effective porosity of the porous medium at the time of the displacement and the amount of solute that is deposited or removed from the porous medium. These parameters may be better determined through multiparametric matching of the model to the data obtained in the laboratory. In order to evaluate the application of the TCM model, two sets of experiments (A and B), totaling 9 tests, were carried out. The tests were conducted with two brines displaced in carbonate rock samples. The concentration evolution along the porous medium was measured by X-Ray Computed Tomography (CT). The vast amount of data from the concentration profiles determined from the CT images from set A was analyzed and matched to the TCM model through the simulated annealing metaheuristic method (Simulated Annealing, SA). The global matching procedure, considering all curves in the concentration history, was used to determine the governing parameters for the involved phenomena. The amount of data used and the robustness of the method allowed a very good matching of the model to the experimental data. A dispersion coefficient of 0.01cm2/s for a 1 cm3/min flow rate; and 0.05 cm2/s for a 5 cm3/min flow rate was determined. The parameters of mass transfer and of the fluid interaction with the rock porous structure were also evaluated. Experiment B was carried out in order to double check solute deposition while flowing through the rock sample. In the TCM model, the phenomenon was quantified by the fr parameter. The concentration profiles of Experiment B were measured at the input, along the rock sample and at the output. From these profiles a mass balance was carried out to evaluate the fraction of solute deposited (fr) during the experiment. The determined values for fr were 0.2 to 0.4, figures that are consistent with the results obtained with the TCM matching procedure / Doutorado / Reservatórios e Gestão / Doutora em Ciências e Engenharia de Petróleo

Rentgenová počítačová tomografie je metoda sloužící ke 3D zobrazování vnitřní struktury objektů. Mikrostruktura objektů ukrývá důležité informace, které mohou být použity k jejich charakterizaci. Tato práce podává spojení mezi datasety získanými pomocí rentgenové počítačové mikrotomografie a oblastí statistického zpracování dat. Výstupem metody, pak bude klasifikace vzorků na základě informací o jejich mikrostruktuře. Z výsledků klasifikace vzorků, pak můžeme vyvodit různé hypotézy týkající se původu vzorků. Tato práce by mimo jiné mohla sloužit jako takový nový vhled do problematiky kombinace dat různého původu, pomocí metod statistické analýzy.

At present, the medical industry rapidly develops new imaging techniques and improves the imaging methods. Simultaneously also are developed new methods for processing data acquired by these methods. Especially in the past few years has become very used method of registration data, which leads to image transformations of the same scene so that the condition as possible. The work deals with the method of processing data that provides detailed information to individual structures, developments of individual structures over time, allows to simultaneously displayanatomical and physiological information or preprocessing data for further processing.

The aim of the thesis is to design and implement a simulator of image reconstruction during x-ray computed tomography fluoroscopy. Apart from quantitative evaluation of particular imaging process parameters influence, the intended program application will lie in optimization of these parameter values. Introductory part is focused on brief theoretical description of x-ray computed tomography imaging process. Emphasis is placed on fluoroscopy-specific approaches, particularly the division of scanned projections into chosen amount of sectors as well as fluoroscopic imaging process evaluation methods. The subsequent part deals with program implementation and its limitations and sketches the possible working framework. Moreover, one of the chapters is devoted to optimization of imaging process parameters measurement. The final part aims at impact analysis of particular process parameters as well as fluoroscopic imaging process optimization approaches. The thesis consists also of a didactic simulator enabling real-time intervention simulation with manual instrument manipulation. Since both simulators are intended for teaching purposes, the thesis is supplemented with a laboratory exercise draft.

Dans un contexte industriel, la tomographie 3D par rayons X vise à imager virtuellement une pièce afin d'en contrôler l'intérieur. Le volume virtuel de la pièce est obtenu par un algorithme de reconstruction, prenant en entrées les projections de rayons X qui ont été envoyés à travers la pièce. Beaucoup d'incertitudes résident dans ces projections à cause de phénomènes non contrôlés tels que la diffusion et le durcissement de faisceau, causes d'artefacts dans les reconstructions conventionnelles par rétroprojection filtrée. Afin de compenser ces incertitudes, les méthodes de reconstruction dites itératives tentent de faire correspondre la reconstruction à un modèle a priori, ce qui, combiné à l'information apportée par les projections, permet d'améliorer la qualité de reconstruction. Dans ce contexte, cette thèse propose de nouvelles méthodes de reconstruction itératives pour le contrôle de pièces produites par le groupe SAFRAN. Compte tenu de nombreuses opérations de projection et de rétroprojection modélisant le processus d'acquisition, les méthodes de reconstruction itératives peuvent être accélérées grâce au calcul parallèle haute performance sur processeur graphique (GPU). Dans cette thèse, les implémentations sur GPU de plusieurs paires de projecteur-rétroprojecteur sont décrites. En particulier, une nouvelle implémentation pour la paire duale dite à empreinte séparable est proposée. Beaucoup de pièces produites par SAFRAN pouvant être vues comme des volumes constants par morceaux, un modèle a priori de Gauss-Markov-Potts est introduit, à partir duquel est déduit un algorithme de reconstruction et de segmentation conjointes. Cet algorithme repose sur une approche bayésienne permettant d'expliquer le rôle de chacun des paramètres. Le caractère polychromatique des rayons X par lequel s'expliquent la diffusion et le durcissement de faisceau est pris en compte par l'introduction d'un modèle direct séparant les incertitudes sur les projections. Allié à un modèle de Gauss-Markov-Potts sur le volume, il est montré expérimentalement que ce nouveau modèle direct apporte un gain en précision et en robustesse. Enfin, l'estimation des incertitudes sur la reconstruction est traitée via l'approche bayésienne variationnelle. Pour obtenir cette estimation en un temps de calcul raisonnable, il est montré qu'il est nécessaire d'utiliser une paire duale de projecteur-rétroprojecteur. / In industry, 3D X-ray Computed Tomography aims at virtually imaging a volume in order to inspect its interior. The virtual volume is obtained thanks to a reconstruction algorithm based on projections of X-rays sent through the industrial part to inspect. In order to compensate uncertainties in the projections such as scattering or beam-hardening, which are cause of many artifacts in conventional filtered backprojection methods, iterative reconstruction methods bring further information by enforcing a prior model on the volume to reconstruct, and actually enhance the reconstruction quality. In this context, this thesis proposes new iterative reconstruction methods for the inspection of aeronautical parts made by SAFRAN group. In order to alleviate the computational cost due to repeated projection and backprojection operations which model the acquisition process, iterative reconstruction methods can take benefit from the use of high-parallel computing on Graphical Processor Unit (GPU). In this thesis, the implementation on GPU of several pairs of projector and backprojector is detailed. In particular, a new GPU implementation of the matched Separable Footprint pair is proposed. Since many of SAFRAN's industrial parts are piecewise-constant volumes, a Gauss-Markov-Potts prior model is introduced, from which a joint reconstruction and segmentation algorithm is derived. This algorithm is based on a Bayesian approach which enables to explain the role of each parameter. The actual polychromacy of X-rays, which is responsible for scattering and beam-hardening, is taken into account by proposing an error-splitting forward model. Combined with Gauss-Markov-Potts prior on the volume, this new forward model is experimentally shown to bring more accuracy and robustness. At last, the estimation of the uncertainties on the reconstruction is investigated by variational Bayesian approach. In order to have a reasonable computation time, it is highlighted that the use of a matched pair of projector and backprojector is necessary.

The importance of aggregate structure and air voids distribution for asphalt mixture rutting and cracking performance has been well established on the basis of experience and is well documented in the literature. Past and current investigations are limited to assessment of performance based on macroscopic behavior due to the difficulty associated with the quantitative measurement and analysis of the internal structure of asphalt mixtures. Lately, technical advances in X-ray Computed Tomography (CT) and image processing and analysis has made possible to bring the attention also to the internal structure of asphalt mixtures. SPT results from asphalt field cores, including dynamic modulus (before and after loading) and microstrain accumulation (flow number), exhibited significant variability; most likely, induced by irregularities in the core shape. The analysis of aggregate structure and air voids distribution performed trough X-ray CT, clearly identified segregation in the asphalt mixture as a key factor that induced variability in SPT results. / QC 20120320