Dissertationen zum Thema „Tomographie par absorption des rayons X“
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Shi, Qihan. „Étude multiéchelle des composites par tomographie de rayons X“. Paris, CNAM, 2003. http://www.theses.fr/2003CNAM0490.
In this dissertation, one presents a multiscaled research by the X-ray computerized tomography to characterize the wooden plastic materials and rubbers about their physicochemical and viscoelastic properties, as well as their damage and fracture behaviours. At mesoscopic level, the homogeneous study on phase and the non-destructive control on defects and inclusions demonstrate the powerful capacity of our medical scanner. On the microscopic scale, the phenomena of crystallisation by tension and under the low temperature have been interpreted by the linear coefficient of X-rays attenuation. From macroscopic point of view, the data obtained from various mechanical tests such as fracture, cavitations, relaxation and creep have been compared with tomographic results. Finally, a table is shown to compare the CT with other microscopic method
Cazasnoves, Anthony. „Représentation par maillage adapté pour la reconstruction 3D en tomographie par rayons X“. Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0121/document.
3D X-Ray computed tomography reconstruction is a method commonly used, nowadays, in both medical and non destructive testing fields to reconstruct a 3D object from a set of its 2D projections. The reconstruction space usually is sampled on a regular grid of isotropic voxels, thus inducing an increase in the number of cells used in order to get a satisfactory spatial resolution. This representation hence have a direct impact on the growth in computational cost of each reconstruction iteration and imposes the storage of volumes of considerable memory storage footprints. This dissertation introduces an approach to build an adapted sampling of the object of interest directly from a sparse dataset of projections and prior to any tomographic reconstruction. Instead of the usual voxel lattice, we make use of a tetrahedral mesh that tightly fits the object structure : cells density increases close to its interfaces and decreases in homogeneous regions. To create such a mesh, the first step of this work consists in the detection of edges in the 2D projection images. Segmentation quality being paramount for further stages, we introduce a statistical approach to automatically select crucial parameters of the selected edge detector - Canny's filter. This structural information then is merged within the 3D volume of reconstruction as a pointcloud adequately sampling the 3D interfaces of the studied object. To do so, we perform a direct backprojection of the 2D edge maps to obtain a rough 3D map of the desired interfaces. The points composing the cloud are placed according to this map by automated filtering of the rough map. This automation is attained by statistical approach. The adapted mesh is finally obtained by classical constrained Delaunay tetrahedralization algorithm on this cloud. CT reconstruction is performed on this new sampling by using usual iterative algorithms for which suitable models of projector/backprojector are proposed. Our experiments show that, using a sparse dataset - e.g. 30 projections - our method provides pointclouds tightly sampling the object interfaces. The compression achieved in the number of unknowns to estimate and in memory consumption for volume storage is sizable, vouching for the relevance of this sampling. Produced reconstructions are promising and the quality of meshes sufficient to contemplate their use in simulation applications, such as finite element methods
Mandolini, Tommaso. „Microstructural evolution of polymineralic aggregates deformed under high pressure and temperature : an in-situ and post-mortem study on olivine+serpentine“. Electronic Thesis or Diss., Université de Lille (2022-....), 2022. http://www.theses.fr/2022ULILR047.
At plate tectonic boundaries, the lithosphere is deformed and strain localization occurs up to kilometers-scale, which can manifest in form of shear zones. The strain localization suggests the strength of the lithosphere is locally weakened. The formation of interconnected layers of weaker minerals in the lithosphere is a potential mechanism to achieve such weakening. Serpentinized peridotite is commonly found within and between tectonic plates. It is mainly composed of olivine and serpentine minerals. The latter is generally accepted to be weaker than olivine at geological strain rates. During deformation, strain is thus expected to preferentially partition into serpentine than into olivine. This can lead to the formation of interconnected weak layers (IWL) of serpentine where strain localizes.The present work is based on microstructural investigation to infer the strain accommodation in rocks. Olivine+serpentine aggregates with two compositions (10 and 20 vol.% serpentine) are used as a proxy for partially serpentinized peridotites. The aggregates are experimentally deformed in torsion at high pressures (HP, > 2 GPa) and high temperatures (HT, > 300°C) at an equivalent strain rate of 10-4 s-1. The experiments are coupled with in-situ absorption contrast X-ray tomography. I obtain 2D and 3D information on connectivity and structural layering in the microstructure of the ‘weak' serpentine. Electron microscopy is performed on recovered samples to link the in-situ X-ray tomography observations to the plastic properties of the phases.I first outline experimental and image-data processing procedures specific to in-situ HP experimental deformation. Then, I study the deformation of the aggregates with increasing shear deformation at multiple scales of observations. The main aim is to observe the onset and development of IWL in its microstructure. The relations between the morphology and plastic properties of the phases in the rock are investigated to understand the strain localization in serpentinized peridotite.The main results show the deformation regime in olivine+serpentine aggregates can be described as semi-brittle, with the dominant phase of olivine (‘stronger') mainly displaying brittle deformation, whereas the serpentine (‘weaker') showing a dominant ductile-style deformation. A strain γ of ca. 4-5, serpentine content of ca. 20 vol.%, and initial fraction of large clusters >15 vol.% determine the condition for IWL configuration in the olivine+serpentine aggregates. Conversely, at serpentine content of ca. 10 vol.%, IWL do not occur, independently of strain or initial clusters size distribution of serpentine. This is more consistent with a load-bearing framework (LBF) behavior, where the stronger olivine grains are jammed, and during deformation crush one another, leading to grain size reduction and accommodating much of the deformation in the rock. These findings suggest contents of serpentine >10 vol.% or ca. 20 vol.% define a threshold for crucial changes in the morphology, connectivity, percolation, of the weak serpentine in serpentinized peridotites under shear. This may lead to important changes in deformation behavior and mechanical properties of the rock.In light of these findings, I give some perspectives for strain localization and shear zones initiation in the lithosphere
Wils, Patricia. „Tomographie par rayons X : correction des artefacts liés à la chaîne d'acquisition“. Phd thesis, INSA de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00708545.
Zhang, Tao. „Imagerie multi-résolution par tomographie aux rayons X : application à la tomographie locale en science des matériaux“. Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00876871.
Thibaudeau, Christian. „Développement d'algorithmes de reconstruction statistique appliqués en tomographie rayons-X assistée par ordinateur“. Mémoire, Université de Sherbrooke, 2010. http://savoirs.usherbrooke.ca/handle/11143/1539.
Laloum, David. „Tomographie par rayons X haute résolution : application à l'intégration 3D pour la microélectronique“. Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAY067/document.
In this thesis, an original non-destructive 3D characterization technique has been developed : the X-ray tomography hosted in a scanning electron microscope. This instrument is not widely used in the microelectronics field. This computed tomography (CT) system has been used for the high resolution analysis of metallic interconnections such as copper pillars and through silicon vias (TSVs). These components are widely used in the field of 3D integration to make vertical stacks of interconnected chips.The most significant contributions of this thesis are : (1) the enhancement of the analytical capabilities of the instrument. Many studies – simulations and experiments – have been performed in order to determine and improve the 2D and 3D resolutions of this imaging system. It has been shown that the 2D resolution of this instrument can reach 60 nanometers. The quality of the projections and reconstruction has also been improved through the implementation of iterative reconstruction algorithms and various projections alignment methods. (2) The reduction of the scanning time by a factor 3 through the implementation of constrained reconstruction techniques such as the reconstruction method based on the total variation minimization. (3) The application of effective correction algorithms for removing reconstruction artefacts due to the polychromaticity of the X-ray beam. (4) The application of all these reconstruction methods and algorithms on real cases encountered by materials engineers
Arrio, Marie-Anne. „Dichroisme circulaire magnetique d'aimants a base moleculaire par absorption des rayons x“. Paris 11, 1995. http://www.theses.fr/1995PA112140.
Fosso, Philippe. „Etude in-situ de l'endommagement des matériaux composites à matrice organique par tomographie à rayons X“. Châtenay-Malabry, Ecole centrale de Paris, 1992. http://www.theses.fr/1992ECAP0250.
Freud, Nicolas. „Modélisation et simulation de systèmes d'imagerie par rayons X ou gamma“. Lyon, INSA, 2003. http://theses.insa-lyon.fr/publication/2003ISAL0061/these.pdf.
This PhD thesis is devoted to the development of a computer code enabling to simulate in a short time realistic radiological images, taking into account the main physical parameters acting in an X- or gamma-ray imaging chain. In the first part, we carry out a general survey of the state of the art in the field of radiation transport simulation. This study leads us to choose a deterministic approach and to seek specific algorithms, devoted to the simulation of radiological images and, at first, accounting only for the directly transmitted radiation. The proposed solutions, which emphasize execution speed and robustness, are implemented in a code named VXI (Virtual X-ray Imaging). VXI makes it easy to carry out simulations in realistic imaging configurations (polychromatic spectrum, objects with complex geometry. . . The second part of this thesis broaches the simulation of the radiation scattered by the inspected objects. We propose a deterministic method to simulate first-order photon scattering without having recourse to a parallel computing architecture. This method is validated by comparing its results with the ones given by the Monte Carlo code Geant4
Freud, Nicolas Babot Daniel. „Modélisation et simulation de systèmes d'imagerie par rayons X ou gamma“. Villeurbanne : Doc'INSA, 2005. http://docinsa.insa-lyon.fr/these/pont.php?id=freud.
Chap. 2 et 4 rédigés en anglais. En appendice, 1 article rédigé en anglais intitulé "Optimal calibration via virtual X-ray imaging for dual-energy techniques : application to glass wool", issu du Colloque "Six international Conference on quality control by artificial vision" et paru dans la revue "SPIE", vol. 5132, 2003, p. 422-432. Titre provenant de l'écran-titre. Bibliogr. p. 143-155.
Bonnin, Anne. „Étude d'un système portable d'inspection par rayonnement X utilisant les effets combinés d'absorption multi-énergies, de diffusion et diffraction X sur la matière“. Lyon, INSA, 2009. http://theses.insa-lyon.fr/publication/2009ISAL0112/these.pdf.
This thesis is focused on the discrimination between explosives and common materials by X-rays. Three X-ray based methods are described: multi-energy transmission, Compton scattering and diffraction. These three methods are discussed from a theoretical and experimental point of view. The memory consists of four parts. After describing the general context of the study, the physical phenomena and the properties of the involved materials are given. In a second part devoted to transmission, the principle of multi-energy 2D imaging is presented. Then, we develop an approach to dual-energy 3D imaging, which allows a representation of materials in a database of effective density and atomic number. This approach allows to discriminate a numbers of explosives. In the third part, the X-ray diffraction is discussed in order to identify materials by their spectral signature. The semi-crystalline and crystalline materials are recognized, but not amorphous ones. The fourth part focuses on Compton scattering. We tested different methods of acquisition: pinhole, coded masks and a X-rays scanning technique using a pencil beam. These techniques allow to obtain images of objects. The device is placed on the same side of the object, which is particularly interesting in practical field. In summary, we discuss the complementarity of information extracted from these differents techniques to specify the characteristics of a portable system for land analysis
MA, QING. „Etude structurale des verres semiconducteurs as#xte#1##x par absorption et diffusion anormale des rayons x“. Paris 6, 1992. http://www.theses.fr/1992PA066667.
Abbasi, Kévin. „Etude de L'endommagement en fluage de cuivre par tomographie à rayons X et polissages successifs“. Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2013. http://tel.archives-ouvertes.fr/tel-00966919.
Lenoir, Nicolas. „Comportement mécanique et rupture dans les roches argileuses étudiés par micro tomographie à rayons X“. Université Joseph Fourier (Grenoble), 2006. http://www.theses.fr/2006GRE10025.
WITHIN THE FRAMEWORK OF FEASABILITY STUDIES OF UNDERGROUND REPOSITORIES FOR RADIOACTIVE WASTE, THE STUDY OF PERMEABILITY EVOLUTION WITH DAMAGE OF THE HOST LAYER IS CRUCIAL. THE GOALS OF THIS WORK WERE : (i) TO CHARACTERIZE EXPERIMENTALLY THE DAMAGE OF TWO CLAYEY ROCKS (BEAUCAIRE MARL AND EAST SHALE) WITH X-RAY MICRO TOMOGRAPHY, (ii) TO DEVELOPP A HIGH PRESSURE TRIAXIAL SET-UP ADAPTED TO PERMEABILITY MEASUREMENT ON VERY LOW PERMEABILITY ROCKS. A NUMBER OF ORIGINAL TRIAXIAL DEVICES HAVE BEEN REALISED TO CHARACTERIZE DAMAGE OF CLAYEY ROCKS, UNDER DEVIATORIC LOADING, WITH X-RAY MICRO TOMOGRAPHY ON A SYNCHROTRON BEAMLINE AT THE ESRF (GRENOBLE). LOCALIZED DAMAGE AND ITS EVOLUTION HAVE BEEN CHARACTERIZED AT A FINE SCALE (OF ORDER OF TEN MICRONS). DIGITAL IMAGE CORRELATION TECHNIQUES, EXTENDED TO 3D IMAGES, HAVE BEEN USED TO MEASURE INCREMENTAL STRAIN FIELDS FROM TOMOGRAPHIC IMAGES. WE DEMONSTRATED THAT THESE TECHNIQUES ARE VERY USEFUL IN THE STUDY OF THE LOCALIZED DAMAGE OF GEOMATERIALS AND ESPECIALLY FOR THE INITIATION. A HIGH PRESSURE TRIAXIAL DEVICE HAS BEEN REALISED TO MEASURE PERMEABILITY EVOLUTION OF THE EAST SHALE AS A FUNCTION OF APLLIED STRESS (ISOTROPIC AND DEVIATORIC). THE PARTICULARITY OF THIS SET-UP IS THE SMALL SIZE OF THE TEST SPECIMEN (CYLINDER OF 10MM IN DIAMETER AND 20MM IN HEIGHT) WHICH ALLOWS SIGNIFICANT REDUCTION OF TEST DURATION
Abbasi, Kévin. „Etude de L’endommagement en fluage de cuivre par tomographie à rayons X et polissages successifs“. Thesis, Saint-Etienne, EMSE, 2013. http://www.theses.fr/2013EMSE0706/document.
Power law creep damage is one of the most intriguing unsolved phenomena of materials science. Models based on continuum mechanics generally predict a much higher strain to failure, as well as a much longer creep lifetime than experimentally observed values. This thesis highlights two aspects of this problematic by analyzing creep damage in copper using in situ synchrotron tomography and 3D reconstruction of the damaged polycrystal structure by serial sectioning.Damage in terms of the area fraction of voids was first identified in slices of tomographic reconstructions of creep deformed copper. The local and global evolution of cavities area fraction was checked against the Cocks and Ashby model and it was found that the model overestimates creep lifetime and underestimates damage development. The importance of the initial damage heterogeneity and the role of damage localization are also emphasized. It was found that the amplitude of the largest damage fluctuation increases parabolically as a function of cavity’s mean area fraction.An improved serial sectioning method based on surface profilometry was developed, which allows the accurate measurement of the removed local material thickness. The 3D reconstructions enabled identifying the creep voids and the grains of the polycrystal. It was shown that with the exception of the void shape, the relationship between void location at a given grain boundary and crystallographic orientation of the neighbor grains is similar in samples deformed by different creep mechanisms. The relative population of creep voids is higher at simple grain boundaries than at triple junctions. Voids found at a triple boundary, however, are larger
Saur, Hugo. „Étude des microstructures par tomographie à rayons X : application aux roches clastiques à grain fin“. Electronic Thesis or Diss., Pau, 2022. http://www.theses.fr/2022PAUU3005.
The study of the microstructure of rocks is essential for our contemporary and future challenges in energy, engineering and construction. Furthermore, this study allows us to characterize the geological deformation processes that led to the current state of geological formations. Fine-grained clastic rocks, commonly called "shales", represent about two-thirds of all sedimentary rocks. 3D data concerning silt-sized grains or clasts embedded in the porous clay-rich matrix of this type of rock are relatively scarce despite the fact that these data are crucial to understand the anisotropic properties of these rocks at the macroscale but also to evaluate the deformation state of the rock matrix. A better understanding of the microstructure of these rocks would allow us to predict their mechanical or physical properties, which are essential for applications in the energy sector, among others. X-ray computed tomography (XCT) is a non-destructive technique providing a 3D image of the microstructure of any object. A direct geometric characterization of the constituents of fine-grained clastic rocks is possible with this technique. Based on XCT images, this thesis aims first to develop methodological aspects to study the 3D shape fabric of silt particles and their spatial distribution. The moments of inertia of segmented grains from 3D digital images are used for this development. We then present applications on fine-grained rocks with a sedimentary fabric and on deformed fine-grained rocks with a tectonic fabric. The first application part of the thesis focuses on the same lithologic unit having experienced different amounts of deformation. Samples from the South Pyrenean Basin and samples from a historical outcrop in the Central Appalachians were collected. We provide new data on the evolution of the 3D shape of grains and pores at the micrometer scale and their arrangement in the rock matrix with respect to the deformation intensity. The obtained data allow discussing the deformation mechanisms at the grain scale of the different mineralogical phases. However, the limited size of the imaged samples by means of XCT (≤ 2 mm diameter) raises the question of the representativeness of these analyses. On the South Pyrenean site, some samples are studied in more detail to evaluate the homogeneity of the results. We show that the XCT data complement the indirect petrophysical measurements by providing access to localized sub-fabrics that are integrated in a bulk measurement of the rock fabric. The limits are reached when the characteristic length of the deformation structures are on the order of the sample size imaged by XCT. In the second application part, samples from turbiditic systems of the South Pyrenean basin are analyzed. These systems, when deformed in compressive tectonic settings, record the same amount of shortening differently expressed in the various siliciclastic matrices. The results obtained from the shape data of the clasts are compared to our bulk magnetic fabric measurements and show a good consistency. The methodology presented in this work can be extended to other types of porous and granular media for a better understanding of the influence of fabric anisotropy on their macroscopic properties and mechanical behavior
Petit, Clémence. „Etude des propriétés mécaniques de matériaux cellulaires par la tomographie aux rayons X et par modélisation par éléments finis“. Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0130/document.
Cellular materials are highly porous systems for which two scales are mainly important: the mesostructure and the microstructure. The mesostructure corresponds to the architecture of the materials: distribution of solid phase “walls” and macroporosity and can be characterized by X-ray tomographic low resolution images. The link between the architecture of the materials and the mechanical properties has been frequently studied. The microstructure refers to the characteristics of the solid phase. Its microstructural features (presence of a secondary phase or of defects due to the sintering) can have a strong influence on the macroscopic properties. The aim of this work is to link the morphological and microstructural features of metallic and ceramic based cellular materials and their mechanical properties thanks to X-ray tomography and finite element modelling. A new method combining X-ray tomography at different resolutions, image processing and creation of finite element modelling enabled to take into account some microstuctural features of the cellular samples. Four different cellular materials were studied as model materials: aluminium foam fabricated by a liquid state process, cobalt periodic structures made by additive manufacturing, β-TCP porous samples fabricated by conventional sacrificial template processing route and hydroxyapatite/β-TCP composites made by additive manufacturing (robocasting). The metal based materials were provided by colleagues while the ceramic based porous materials were fabricated in the frame of the current study. For each type (metals or ceramics), a stochastic and a regular structure have been compared. For implementing the multiscale method developed in this work, the samples were firstly scanned in a so called “local” tomography mode, in which the specimen is placed close to the X-ray source. This allowed to reconstruct only the small irradiated part of the sample and to obtain a magnified image of a subregion. These images enable to observe some details which are not visible in lower resolution. Different image processing steps were performed to generate low resolution images including microstructural features imaged at high resolution. This was done by a series of thresholding and scaling of the high resolution images. The result of these processing steps was an image of the initial sample. Then, in situ mechanical tests were performed in the tomograph to follow the deformation of the sample at low resolution. The above mentioned initial images were used to produce finite element meshes. Special Java programs were adapted to create finite element input files from initial images and meshes. The initial images containing information about the solid phase, the images from the mechanical tests and the finite element models were combined to explain the mechanical behaviour of the sample by linking the experimental damage locations in the sample and the simulated stress concentration sites
Kawerk, Elie. „Dynamique subfemtoseconde de molécules isolées par diffusion inélastique résonante de rayons X“. Paris 6, 2013. http://www.theses.fr/2013PA066237.
The absorption of an X-ray photon by a molecular system leads to the promotion of an electron occupying a core level to highly unoccupied virtual orbitals. Following the absorption, the system could evolve following different paths : an electronic path (ex :X-ray fluorescence, Auger decay), and a nuclear path (ex :molecular dissociation). In the first part of this thesis, we present a combined experimental and theoretical study of the X-ray absorption spectra around the chlorine L edge of the molecules C2H3Cl and iso-C2H2Cl2 in gas phase. The spectra of the two molecules were simulated numerically using a Configuration Interaction method (CI) taking into account the spin-orbit coupling. The numerical simulations are in good agreement with the experimental measurements, suggesting new assignements of the major observed spectal bands. The calculations extended to the cis and trans isomers of dichloroethylene, compared to C2H3Cl and iso-C2H2Cl2 show that the evolution of the spectral profile results from an increasing electronegativity scale of the radicals which seems to respect the following order : C2H2Cl/cis/trans/iso-C2H3. In the second part of this thesis, we have studied the Resonant Inelastic X-ray Scattering (RIXS-K) spectra around the chlorine K edge of iso-C2H2Cl2 in gas phase. The following work enabled us to determine the nature of the core excited electronic states involved in the scattering, and to bring out particularly, some electronic transitions of weak intensity which are hardly observed with the use of traditional spectroscopies (X-ray absorption). We have also shown an evolution of the K emission spectra with the incoming photon energy. The evolution of the spectral profile of the K lines highlights the existence of nuclear dynamics occurring in the 1A’ state (elongation of the C-Cl bond) on a femtosecond timescale
Cendre, Emmanuelle. „Tomographie à haute résolution par rayons X : application à l'étude de la perte osseuse chez le sujet âgé“. Lyon, INSA, 1998. http://www.theses.fr/1998ISAL0055.
This thesis concerns the study of age-related bone loss mechanisms. The aim is to determine if a high resolution computed tomography (HRCT) system with 150μm resolution is sufficient to-predict non invasively mechanical properties in ewe lumbar vertebrae and in human cancellous bone (vertebrae and os calcis). A first HRCT system allowed to obtain two-dimensional slices with 150 μm resolution. We built a second HRCT system with an adjustable resolution between 200 and 8 μm. Specific segmentation methods were developed in order to extract structural and connectivity parameters. Moreover, bone architecture was characterized by textural parameters. In a first time, we developed on animal model different techniques to evaluate the cancellous bone's quality: its density (physical density and density evaluated by dual x-ray absorptiometry), its structure (estimated by histomorphometry and HRCT) and its mechanical properties. On human os calcis, ultrasonic measures were also performed. The HRCT system (resolution 150 ~rn) was evaluated by referring to the standard histomorphometric technique. The results obtained enabled us to derive significant correlations for most of the measured parameters. Moreover, the strong correlations obtained between HRCT structural parameters and mechanical properties are of the same magnitude as those determined from histomorphometry, but with the remarkable advantage that HRCT is a non invasive method. On the os calcis, significant correlations were equally obtained between compressive properties and the measures of ultrasound attenuation or apparent density. In conclusion, the resolution (150 μm) of our HRCT system enabled the mechanical properties of human cancellous bone to be partly predicted. This type of resolution allows us to consider the possibility of perfecting an in vivo HRCT system on peripheral bone. Further studies are necessary to confirm whether HRCT and ultrasound measurements on the os calcis could help to estimate vertebral rnechanical properties and to predict the vertebral fracture risk
Barbusse, Danielle. „Contribution à la caractérisation des matériaux : étude des couches minces, multicouches et superréseaux III-V et II-VI par double diffraction des rayons X (composition, qualité, contraintes) : étude structurale par absorption X au seuil K d'une série de complexes du cobalt et du fer, XANES et EXAFS de laboratoire“. Montpellier 2, 1991. http://www.theses.fr/1991MON20189.
Wang, Han. „Méthodes de reconstruction d'images à partir d'un faible nombre de projections en tomographie par rayons x“. Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00680100.
Quinto, Michele Arcangelo. „Méthode de reconstruction adaptive en tomographie par rayons X : optimisation sur architectures parallèles de type GPU“. Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENT109/document.
Tomography reconstruction from projections data is an inverse problem widely used inthe medical imaging field. With sufficiently large number of projections over the requiredangle, the FBP (filtered backprojection) algorithms allow fast and accurate reconstructions.However in the cases of limited views (lose dose imaging) and/or limited angle (specificconstrains of the setup), the data available for inversion are not complete, the problembecomes more ill-conditioned, and the results show significant artifacts. In these situations,an alternative approach of reconstruction, based on a discrete model of the problem,consists in using an iterative algorithm or a statistical modelisation of the problem to computean estimate of the unknown object. These methods are classicaly based on a volumediscretization into a set of voxels and provide 3D maps of densities. Computation time andmemory storage are their main disadvantages. Moreover, whatever the application, thevolumes are segmented for a quantitative analysis. Numerous methods of segmentationwith different interpretations of the contours and various minimized energy functionalare offered, and the results can depend on their use.This thesis presents a novel approach of tomographic reconstruction simultaneouslyto segmentation of the different materials of the object. The process of reconstruction isno more based on a regular grid of pixels (resp. voxel) but on a mesh composed of nonregular triangles (resp. tetraedra) adapted to the shape of the studied object. After aninitialization step, the method runs into three main steps: reconstruction, segmentationand adaptation of the mesh, that iteratively alternate until convergence. Iterative algorithmsof reconstruction used in a conventionnal way have been adapted and optimizedto be performed on irregular grids of triangular or tetraedric elements. For segmentation,two methods, one based on a parametric approach (snake) and the other on a geometricapproach (level set) have been implemented to consider mono and multi materials objects.The adaptation of the mesh to the content of the estimated image is based on the previoussegmented contours that makes the mesh progressively coarse from the edges to thelimits of the domain of reconstruction. At the end of the process, the result is a classicaltomographic image in gray levels, but whose representation by an adaptive mesh toits content provide a correspoonding segmentation. The results show that the methodprovides reliable reconstruction and leads to drastically decrease the memory storage. Inthis context, the operators of projection have been implemented on parallel archituecturecalled GPU. A first 2D version shows the feasability of the full process, and an optimizedversion of the 3D operators provides more efficent compoutations
Duvauchelle, Philippe. „Tomographie par diffusion Rayleigh et Compton avec un rayonnement synchroton : application à la pathologie cérébrale“. Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE19003.
Borissenko, Elena. „Étude structurale par diffraction, absorption des rayons X et simulations Monte-Carlo de matériaux zéolithiques“. Thesis, Nancy 1, 2008. http://www.theses.fr/2008NAN10074/document.
The organic-inorganic composites with zeolite as host matrix are mostly studied to produce performing materials for non-linear optics, optoelectronics, optical/magnetic memories. The performances of these new materials are driven by the coupling between the guest and host properties, in particular, by the molecularframework, molecular-cation interactions. Actually, only few accurate crystallographic structures of such composite are available in literature, so the guest-host interactions are still little known. In this work, I’m interested in the crystallographic structures of two composites: temperature induced spin crossover Co2+(bpy)3-zeolite X and dmpNA-mordenite that have to produce the Second Harmonic Generation signal. In the case of magnetic composite, I have particularly studied the composite precursor, zeolite Na,Co-X, in the different hydration states in order to follow an insight on structural modifications induced by water molecules desorption. Because of desorder, the structural studies are difficult. Nevertheless, the complementarities of the experimental (X-ray Diffraction and Absorption) and simulations (Monte-Carlo) approaches were fruitful to obtain the accurate partially/completely hydrated and dehydrated structures. These structures clearly show the cell volume contraction and cation migrations over dehydration that where caused by the strong cobalt –framework interactions. The crystal structure of dmpNA-mordenite has been determined from high resolution synchrotron powder diffraction and showed that zeolite straight channels are completely loaded with dmpNA molecules with a moderate tilt angle relative to the channel axe which is favourable to frequency doubling signal
Borissenko, Elena Souhassou Mohamed Porcher Florence. „Étude structurale par diffraction, absorption des rayons X et simulations Monte-Carlo de matériaux zéolithiques“. S. l. : Nancy 1, 2008. http://www.scd.uhp-nancy.fr/docnum/SCD_T_2008_0074_BORISSENKO.pdf.
Cai, Caifang. „Tomographie par rayons X multi-énergétiques pour l’analyse de la structure interne de l'objet appliquée dans l’imagerie médicale“. Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112244.
Multi-Energy Computed Tomography (MECT) makes it possible to get multiple fractions of basis materials without segmentation. In medical application, one is the soft-tissue equivalent water fraction and the other is the hard-matter equivalent bone fraction. Practical MECT measurements are usually obtained with polychromatic X-ray beams. Existing reconstruction approaches based on linear forward models without counting the beam polychromaticity fail to estimate the correct decomposition fractions and result in Beam-Hardening Artifacts (BHA). The existing BHA correction approaches either need to refer to calibration measurements or suffer from the noise amplification caused by the negative-log pre-processing and the water and bone separation problem. To overcome these problems, statistical DECT reconstruction approaches based on non-linear forward models counting the beam polychromaticity show great potential for giving accurate fraction images.This work proposes a full-spectral Bayesian reconstruction approach which allows the reconstruction of high quality fraction images from ordinary polychromatic measurements. This approach is based on a Gaussian noise model with unknown variance assigned directly to the projections without taking negative-log. Referring to Bayesian inferences, the decomposition fractions and observation variance are estimated by using the joint Maximum A Posteriori (MAP) estimation method. Subject to an adaptive prior model assigned to the variance, the joint estimation problem is then simplified into a single estimation problem. It transforms the joint MAP estimation problem into a minimization problem with a non-quadratic cost function. To solve it, the use of a monotone Conjugate Gradient (CG) algorithm with suboptimal descent steps is proposed.The performances of the proposed approach are analyzed with both simulated and experimental data. The results show that the proposed Bayesian approach is robust to noise and materials. It is also necessary to have the accurate spectrum information about the source-detector system. When dealing with experimental data, the spectrum can be predicted by a Monte Carlo simulator. For a variety of materials, less than 5% estimation errors are observed on their average decomposition fractions.The proposed approach is a statistical reconstruction approach based on a non-linear forward model counting the full beam polychromaticity and applied directly to the projections without taking negative-log. Compared to the approaches based on linear forward models and the BHA correction approaches, it has advantages in noise robustness and reconstruction accuracy
Li, Jia. „Simulation par éléments finis de la propagation de fissures de fatigue dans les matériaux polycristallins imagés par tomographie aux rayons X“. Thesis, Paris, ENMP, 2015. http://www.theses.fr/2015ENMP0079/document.
The short fatigue crack propagation in polycrystal materials depends strongly on microstructure. Although numerous studies of characterisation and of simulation, the prediction of the short fatigue crack propagation remains a challenge.In order to understand the mechanisms of short fatigue crack propagation, an in-situ characterisation by X-ray tomography was carried out at ESRF, using two techniques of tomography. Diffraction Contrast Tomography (DCT) that is a non-destructive method can be used to obtain 3D morphology and grain orientations in an undeformed state of polycrystal materials. Couple with Phase Contrast Tomography (PCT), it allows to characterise the short fatigue crack propagation at different loading stages. Access to this information, it is possible to simulate the short fatigue crack propagation using a 3D reel microstructural mesh reconstructed from the tomographic images.In this work, the elastic anisotropic behaviour in a 3D microstructural mesh is performed. The elastic strain tensors averaged in grains are also compared to the experimental measurements. Then, a new numerical approach is proposed to simulate crack propagation. From a crystal plasticity FE simulation, the crack growth direction is determined by a post processing. Next, the crack is propagated through remeshing. This approach is firstly applied to the single crystals, then to the polycrystal mesh reconstructed from the tomographic images. The grain boundary effects and the crack growth rate are also analysed. By comparing between simulation and experimental crack, the damage indicator is discussed at the end
Longuetaud, Fleur Anne. „Detection et analyse non destructives de caractéristiques internes de billons d'Epicéa commun (Picea abies (L. ) Karst. ) par tomographie à rayons X“. Paris, ENGR, 2005. http://www.theses.fr/2005ENGR0014.
Domputerized tomography allows a direct access to internal characteristics of scanned logs on the basis of density and moisture content variations. The objective of this work is to assess the feasibility of an automatic detection of internal characteristics with the final aim of conducting scientific analyses. The database is constituted by CT images of 24 spruces (Picea abies (L. ) Karst. ) obtained with a medical CT scanner. Studied trees are representative of several social status and are coming from four stands located in North-Eastern France, themselves are representative of several age, density and fertility classes. The automatic processing developed are the following : - pith detection in logs dealing with the problem of knot presence and ring eccentricity. The accuracy of the localisation was less than one mm; - detection of the sapwood/heartwood limit in logs dealing with the problem of knot presence (main source of difficulty). The error on the diameter was 1. 8mm which corresponds to a relative error of 1. 3% ; - detection of the whorls location and comparison with an optical method ; - detection of individualised knots. This process allows to count knots and to locate them in a log (longitudinal position and azimuth); however, the validation of the method and extraction of branch diameter and inclination are still to be developed. An application of this work was a variability analysis of the sapwood content in the trunk: at the within-tree level, the sapwood width was found to be constant under the living crown; at the between-tree level, a strong correlation was found with the amount of living branches. A great number of analyses are possible from our work …
Tonin, Guillaume. „Caractérisation operando des accumulateurs Li/S par tomographie d’absorption et diffraction des rayons X, vers une meilleure compréhension des mécanismes électrochimiques“. Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAI036/document.
The main objective was to identify the degradations phenomena and the limiting processes occurring while cycling Li/S accumulators to therefore put in relation the electrode morphology, the cell design, the electrochemical performances and the degradations phenomena. A new design of operando cell has been developed to be suitable with ESRF experiments. Operando Absorption and X-ray Diffraction tomography technics were performed. Thanks to both technics, the morphological changes and transport limitation kinetics along the 3D positive electrode have been evidenced. In addition, the lithium electrode/electrolyte interface has been characterized and heterogeneous stripping/plating has been evidenced, leading to low electrochemical performances while cycling
Perrenot, Béatrice. „Reconstruction tomographique 3D de stents coronaires avec prise en compte du mouvement en angiographie rotationnelle cardiaque par rayons X“. Lyon, INSA, 2008. http://theses.insa-lyon.fr/publication/2008ISAL0022/these.pdf.
When atherosclerotlc coronary lesions are suspected, current clinical routine relies on X-ray imaging to explore the coronary artery tree. A guidewire carrying a balloon and a stent is conducted through the lesion. The stent position is confirmed by Iwo bal loon radiopaque markerballs and deployed by balloon inflation. The correct sten! deployment can not be checked precisely from the 2D projection images available on current vascular equipment. Lndeed, the sten! which is a sm ali 3D complex mesh with low contras! properties is hardly visible in a number of cases. The physician needs an effective tool to precisely analyse the stent shape in the vessel. We propose to use a set of 2D cone beam projection images acquired und er different points of view to reconstruct 3D images of the stents. Ln this context, the tomographie problem is challenging because of cardiac and respiratory motions. We proposed a formalism to correct motion in X-ray rotational sequences, basis on the motion knowledge of the pair of markerballs in the projection images. We introduce a virtual geometry of acquisition in which the markerballs become motionless. Then, the 3D images are reconstructed with the conventional Feldkamp (FDK) adapted to this new geometry using ali the available images. This work has been assessed on synthetic data and experimental data from the porcine madel. A clinical study is in progress to evaluate our method on human data in Hopital Louis Pradel
Fraczkiewicz, Alexandra. „Développement de la tomographie par rayons X en synchrotron pour l'industrie : application à l'analyse de défaillance en intégration 3D“. Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAY088/document.
This PhD thesis aims at developing new characterization techniques for 3D integration in microelectronics. More specifically, the focus is set on recent ESRF (European Synchrotron Radiation Facility) beamlines, both for 3D imaging by tomography and for strain measurements by Bragg diffraction.3D integration aims at reducing the global microelectronics devices footprint and connections length, by stacking the dies on top of one another instead of setting them one to another. This new geometry however requires new connections, such as copper pillars (CuP) and copper pads, used in hybrid bonding. The monitoring of their fabrication process requires their imaging in three dimensions, and the measure of the strain inside them. Those measurements must be conducted on large areas (100 µm2), with high resolution (500 nm for strain and 100 nm for imaging). Moreover, given the industrial context of this study, the characterization methods must be as routine and automatic as possible.To answer those needs, several techniques have been developed in this work.Two 3D imaging techniques have been made compatible with the requirements of 3D integration characterization. A Slice and View procedure has been implemented inside a single beam PFIB, leading to large volumes 3D automated imaging. The tomography workflow accessible on the ID6A beamline of the ESRF has been adapted, in order to limit the human intervention and beam times. This leads to possible statistical measurements on this beamline.Strain measurements have been conducted on the ID01 beamline of the ESRF, on silicon and copper stacks meant for direct and hybrid bonding. They allowed for simultenous local strain measurements in two independent layers of silicon, and textit{in situ} measurements in copper.In this work, we show the possibilities of synchrotron based techniques (here, tomography and Bragg diffraction) for the chacracterization of 3D integration devices. We show that, provided some adjustments, these techniques can be used routinely for the microelectronics field
Jouet, Emmanuel. „Mise au point et qualification d'une technique de mesure du taux de présence local par tomographie à rayons X“. Phd thesis, Grenoble INPG, 2001. http://www.theses.fr/2001INPG0088.
MAJID, MUSTAPHA. „Etude structurale des verres de chalcogenures se#1#-#xte#x par absorption des rayons x, et etude du systeme ternaire se-te-sn“. Paris 11, 1996. http://www.theses.fr/1996PA112453.
BRIOIS, VALERIE. „Etude cinetique de l'hydrolyse forcee du sulfate de cerium(iv) suivie par absorption et diffusion centrale des rayons x“. Paris 6, 1991. http://www.theses.fr/1991PA066049.
CHABAUD, SAMUEL. „Structures electroniques du systeme li xmo 2 (m = co, ni) etudiees par diffusion compton et absorption des rayons x“. Paris 6, 2001. http://www.theses.fr/2001PA066045.
Falvard, Simon. „Application de la microtomographie par rayons X à l'étude des dépôts de tsunamis“. Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22686/document.
The study of tsunami deposits is a relatively young science, and even if substantial progress has been made (especially during the last three decades) the techniques available at present day do not allow exhaustive studies of the deposits, weither poor conservation of the deposits, which is a common problem, is to blame, or because of limitations of the techniques themselves. Their spatial resolution often appears to be insufficient for fine deposits (sand size fractions and finer) because of their working principle (lack of three dimensional visualisation of structures on thin sections for instance) or because of the sampling techniques they depend on. This work allowed exploring the applications of an analytic technique, X-ray computed microtomography, which had to this day never used before for the study of tsunami deposits. Three distinct case studies have been made: deposits from the 1755 Lisbon tsunami on the western coast of Spain (Andalusia), deposits from the 1996 tsunami triggered in Karymskoye Lake, and a potential mid-Holocene tsunami deposit at Ninety Mile Beach, western Australia. Problematic linked to sampling techniques and raw data processing and exploitation are addressed. Chosen solutions are exposed. The results are compared to those obtained using techniques whose relevance and usefulness have been proven in previous studies. This technique proves to be extremely useful for structural (deposits inner organisation), textural (grain size distribution, sedimentary fabrics and flow dynamics), and composition (bioclasts and heavy minerals abundances) analyses. Crossing structural and textural analysis of the 1755 Lisbon tsunami deposit unravels deposition modes which go against the usually admitted scenario and offers a new point of view on tsunami deposits
Medeiros, Soares Marcio. „Croissance, structure et magnétisme dans les systèmes à décalage d'échange FM/AFM : approche fondamentale par la physique des surfaces“. Thesis, Grenoble, 2011. http://www.theses.fr/2011GRENY022/document.
Our aim is to study the interaction of antiferromagnetic and ferromagnetic materials with well-defined interface by combining structural, electronic and magnetic techniques using synchrotron light. Our interest is guided by the exchange bias effect in thin ferromagnetic films with perpendicular magnetic anisotropy. The main systems studied in this work were ultra-thin layers of chemically-ordered alloys of FePt and MnPt on Pt(001) and of Fe/Ag(001), eventually coupled to CoO. Our strategy was to find an appropriate surface and, for each coupled bilayer, study the individual growth of each element, alloy or oxide. By controlling a variety of parameters, such as surface structure, cleanliness, deposition rate and temperature, we have got a good understanding of the growth process. The coupled systems obtained were studied in situ by grazing incidence X-ray diffraction and ex situ by magneto-optic Kerr effect, X-ray magnetic circular dichroism and X-ray absorption spectroscopy. The relation between the exchange coupling, which manifests itself by an increase in coercivity and a bias field, and the structural characteristics was discussed for the MnPt/FePt and CoO/Fe interfaces.Keywords: exchange bias, chemically ordered alloy, MnPt, FePt, Fe/Ag(001), surface X-ray diffraction, X-ray absorption, MOKE, synchrotron
Longuetaud, Fleur. „Détection et analyse non destructive de caractéristiques internes de billons d'Epicéa commun (Picea abies (L.) Karst.) par tomographie à rayons X“. Phd thesis, ENGREF (AgroParisTech), 2005. http://pastel.archives-ouvertes.fr/pastel-00001796.
Soares, Marcio. „Croissance, structure et magnétisme dans les systèmes à décalage d'échange FM/AFM : approche fondamentale par la physique des surfaces“. Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00603754.
Roisnel, Thierry. „Etude par spectroscopie d'absorption de rayons X de quelques composés d'intercalation graphitique d'halogénures métalliques“. Phd thesis, Université Sciences et Technologies - Bordeaux I, 1988. http://tel.archives-ouvertes.fr/tel-00621239.
Mirea, Iulia. „Analyse de la microstructure 3D du tissu cardiaque humain à l’aide de la micro-tomographie à rayons X par contraste de phase“. Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI076/document.
Cardiovascular diseases remain one of the most serious health problems, motivating research to deepen our understanding of the myocardial function. To succeed, there is a need to get detailed information about the spatial arrangement of the cardiac tissue components. Currently, our understanding of the cardiac microarcInstitut de Technologie de Harbin - Chineecture is limited by the lack of 3D descriptions of the cardiac tissue at the microscopic scale. This thesis investigates the 3D cardiac tissue microstructure using X-Ray µ-CT phase contrast imaging available at the ESRF. For the first time, 9 human cardiac left ventricle (LV) wall samples are imaged at an isotropic resolution (3.5 µm) and analysed. We focus on the description of the cardiac extracellular matrix (CEM) that is one of the main components of the tissue. The CEM includes: the endomysium that surrounds and separates individual myocytes and capillaries, the perimysium that surrounds groups of myocytes and the epimysium that surrounds the entire heart muscle. Each reconstructed sample is about 30 Gb which represents a large amount of data to process and display. To succeed, we developed an automatic image processing algorithm to binarise each sample by selecting the CEM. We extract statistical features of the ECM, mainly the thickness of the cleavage planes (CP) and the inter-CP distances. The results show that the local 3D arrangement of the CP differs according to their location in the LV (posterior, anterior, septal) and their distance from the apex (more complex). The thickness of the CP extracted from all the samples roughly ranges from 24 µm to 59 µm and the inter-CP distances from 70 µm to 280 µm with significant local variations of the standard deviation. Those new quantitative markers of the ECM of the human cardiac are of main interest for a better understanding of the heart function
Philippe, Julien. „Développement d'une presse portative pour les études in et ex situ sous conditions extrêmes de pression, température et déformation“. Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066008.
High pressures are essential in several scientific field. This will be the case in this thesis with the development of a new device enabling new possibilities tomography and deformation under high pressure and high temperature. It brings the possibility of further scientific studies in the various disciplines that are Earth science, mechanical chemistry, physics of materials and liquids physics
Bouterf, Amine. „Comportement mécanique de la plaque de plâtre étudié par tomographie et essais mécaniques in-situ“. Thesis, Cachan, Ecole normale supérieure, 2014. http://www.theses.fr/2014DENS0010/document.
Lightweight plasterboard is a product composed of a "plaster foam" core whose porosity can reach 75% lined with two sheets of paper. To optimize the compromise between thermal resistance and mechanical strength, it is important to understand and characterize the mechanical behavior of the plasterboard. In the present work, specific methodologies for digital image correlation and identification of the mechanical behavior in highly nonlinear regimes (damage, collapse of porosity, macroscopic cracking ...) have been developed and implemented. A first set of mechanical properties, crucial for handling and placarding, concerns the bending strength. Three and four points bending tests were performed until failure. Digital image correlation was used to follow the kinematic of the test. The behavior of the plasterboard has been identified through a homogenized continuum description based on plate kinematic where the progressive degradation of bending stiffness is described through a damage law. A specific procedure for identification is presented where experimental imperfections and symmetry breakdown are tolerated and accounted for. The analysis shows that the mechanical behavior of the plasterbaord in bending test is controlled primarily by the mechanical properties of the paper lining and the quality of gypsum / paper interface. The failure mechanism in bending test was also identified through in-situ tests performed inside the tomograph. A second category of mechanical properties relates to a normative test “Nail pull test”. Through tests conducted inside the tomograph and the analysis of the kinematics by digital volume correlation, the different key stages of the failure mechanism have been identified. The compaction of the core by the collapse of porosity in compression has been recognized as the limiting factor. In order to better understand the compaction mechanism in-situ spherical indentation tests were performed on foamed samples prepared from the board core. The results from the in-situ experiment show that a compacted zone develops under the indenter, displaying a very sharp boundary with the undamaged material that behaves elastically. To meet the need for estimating accurately the state of multiaxial strain that characterizes this transition, a new methodology is presented. It is an integrated digital volume correlation based on a library of fields adapted to the spherical indentation test and computed from commercial finite element software. Coupling in-situ mechanical tests, digital volume correlation and numerical simulations on the one hand, and integration a priori known information in the identification process on the other hand allowed us to identify a local failure criterion. The behavior of porous plaster was also characterized via homogeneous triaxial tests, by following different loading paths. The triaxial behavior of foamed plaster has been identified. The results are in agreement with those obtained via the identification procedure conducted on the spherical indentation tests
Gassoumi, Mohamed. „Caractérisations, défauts et contraintes internes induites lors du procédé de mise en forme des matériaux composites a matrice thermoplastique par thermoestampage“. Thesis, Nantes, 2018. http://www.theses.fr/2018NANT4094/document.
During their thermo-stamping, prepregs made of thermoplastic polymer matrices and woven fabrics are subjected to large deformation including in-plane and transverse shear, the last deformation mechanism being related to inter-ply friction. Once shaped, prepregs can still deform due to residual stresses induced by their cooling and/or hygrometric variations. In this work, we focused on these two aspects. Firstly, prepregs made of polyamide reinforced by layers of woven fabrics (glass fibre bundles) were subjected to bias extension at high temperatures. The fibrous structure deformed specimens was analysed with X-ray microtomography, allowing fiber bundles deformation mechanism to be emphasized.Some of them are not taken into account in current rheological model developed for prepregs. In addition, using a dedicated apparatus, we performed transverse shear tests to analyse inter-ply friction within prepregs. Experimental results underline the influence of the normal stress, the shear strain rate and the temperature on the interplay friction coefficient. A friction model based on the Hersey number is then fitted. Secondly, we measure the curvatures of deformed prepregs was to estimate, via the modified laminated theory, residual stresses and their variation with temperature and relative humidity
Bergamaschi, Antoine. „Développements méthodologiques et logiciels pour l’imagerie X multimodale par balayage sur la ligne de lumière Nanoscopium“. Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS054/document.
The subject of this thesis is the methodological and software development of tools for processing very large multimodal and tomographic datasets produced on Nanoscopium beamline in the SOLEIL synchrotron. Scanning hard X-ray imaging allows simultaneous acquisition of multimodal information, i.e. of images in which each pixel contains several types of data. Combining these scanning techniques with the FLYSCAN infrastructure, developed for fast data acquisition at Synchrotron SOLEIL, permits to perform multimodal tomographic imaging and tomographic reconstruction during routine user experiments. A main challenge of such imaging techniques is the online processing of the important amount of generated multimodal data. The main outcome of this thesis work is the MMX-I software which is dedicated to processing large 2D/3D multimodal dataset. This software includes an original algorithm for continuous reading of large data volumes, several reduction functions, two phase reconstruction algorithms (integration in Fourier space and iterative technics) and tomographic reconstruction technics (filtered back projection and iterative technics). Every implemented method as well as application allowing to validate the new developments and few evolution perspectives are presented in this thesis manuscript
Davidoiu, Valentina. „Approches non linéaire en imagerie de phase par rayons X dans le domaine de Fresnel“. Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00952854.
Ramos, Aline. „Nucléation et croissance cristallines dans un verre SiO-AlO-LiO étude par microscopie électronique à haute résolution et absorption des rayons X /“. Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37617884b.
Chakchouk, Moez. „Reconstruction tridimensionnelle de vaisseaux sanguins à partir d'un nombre restreints de projections par rayons X issues d'un système d'angiographie multi-vues“. Paris 5, 2009. http://www.theses.fr/2009PA05S008.
In this thesis, we propose a 3D vascular reconstruction method from a limited number of projections acquired by a rotational angiography system. This method consists mainly in generalizing a markov model introduced to resolve the reconstruction problem from two angiography images obtained from a biplane acquisition system. This generalization consists in modifying the data-attachment term in order to consider that projections are obtained from a rotational angiography system. This data-attachment term handles then the case where more than two available projections that are not necessarily acquired from orthogonal viewing angles. The 3D vessel reconstruction is obtained by using the maximum a posteriori (MAP) criterion. This criterion is optimized by applying the simulated annealing iterative algorithm. As for iterative tomographic reconstruction algorithms, our proposed 3D vessel reconstruction method from a limited number of projections, involves a forward projection step. This step consists in computing, at each algorithm's iteration, the projection of the obtained reconstruction solution in order to calculate the data-attachment error. The quality of the forward projection step and particularly the precision of the required estimates have a great impact on the reconstruction algorithm convergence. To improve the volume forward projection computation, we propose to use the adaptive kernel density estimation framework. This new approach has the advantage to be independent to the volume sampling. It takes also into account the acquisition geometry by dealing with both parallel and cone beam projection geometries. Furthermore, the typical case of fixed bandwidth kernel estimate provides a new formalism for computing forward projection of volumes represented with basis functions
Pinson, Sébastien. „Matériaux architecturés pour refroidissement par transpiration : application aux chambres de combustion“. Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI089/document.
In order to cool aero-engine combustion chambers as efficiently as possible, there is today a special interest given to transpiration cooling technology. The cooling air flows through a porous liner in which a large amount of heat can be exchanged by convection. The air injection could then take benefit of the pore distribution to form a more homogeneous protective boundary layer.Partially sintered metallic materials are potential candidates to form these porous liners. The present work focuses on internal heat transfers. It aims to develop a methodology capable of highlighting the most adapted partially sintered architectures to this kind of application.During transpiration cooling, flows and heat transfers are governed by some effective material properties which depends on the porous architecture: the effective solid phase thermal conductivity, the volumetric heat transfer coefficient and the permeability properties. Thanks to experimental works and numerical studies on samples digitized by X-ray tomography, simple relationships are first developed between the effective material properties of partially sintered materials and their architectural parameters. The porosity, the specific surface area and the powder type are selected to predict the effective properties.These relationships are finally integrated into a heat transfer model predicting the thermal performance of a design at working engine conditions. A multi-objective optimization and an analysis of the optimal designs highlight some architectures as being potentially interesting for transpiration cooling. Materials with a low porosity and made of large irregular powders seem to ensure the best trade-off among the different criteria taken into consideration