Дисертації з теми "Simulation and reconstruction"
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Stevenson, Timothy James. "Simulation of Vehicle-Pedestrian Interaction." Thesis, University of Canterbury. Mechanical Engineering, 2006. http://hdl.handle.net/10092/1180.
Повний текст джерелаEarls, Craig P. "Holographic particle image velocimetry : computational simulation and reconstruction." Thesis, Springfield, Va. : Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA372219.
Повний текст джерела"June 1999". Includes bibliographical references (leaves 77-79). Also available online.
Earls, Craig P. (Craig Paul) 1967. "Holographic particle image velocimetry : computational simulation and reconstruction." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80189.
Повний текст джерелаIncludes bibliographical references (leaves 78-80).
by Craig P. Earls.
S.M.
Nav.E.
Desai, Amresh S. "Array-based GPR SAR simulation and image reconstruction." Master's thesis, University of Cape Town, 2002. http://hdl.handle.net/11427/7397.
Повний текст джерелаSubsurface object detection has mainly been carried out using conventional ground penetrating radar (OPR) techniques, which use a single receiving antenna from which a number of range profiles (known as ""A Scope"" images) are assembled to form a two-dimensional data field (known as a ""B Scope"" image). These OPR systems have difficulties with high clutter level, surface reflections, limited ground penetration and the required fine resolution. The resolution in the across track and along track directions is limited by the physical aperture in these directions. This project aims at developing a SAR imaging technique, which uses a single transmitting/receiving antenna to synthesize a two-dimensional planar aperture. Thus a three-dimensional reflectivity image of a scene is generated. The resolution in the across track and along track directions is achieved via a SAR aperture synthesis technique. The depth/range resolution is achieved via the transmission of narrowband Stepped Frequency Continuous Wave (SFCW) signals.
Huynh, Minh Duc. "Reconstruction Volumique de Résultats de Simulation à Base Chimère." Thesis, Pau, 2012. http://www.theses.fr/2012PAUU3051/document.
Повний текст джерелаComputationnal fluid dynamics is an essential step in gas turbine modelling. Continuous optimization of turbines has led to sophisticated geometries, which raises severe issues for the design of adapted simulation grids. The chimera technique aims at relaxing geometry matching constraints by allowing grids overlap. However, post-processing of simulation results performed over chimera grids raises new issues because usual tools are not tuned for this particular geometricconfigurations. In the framework of the MOSART programme of the world competitiveness cluster Aerospace Valley, we have been working in collaboration with Turbomeca in order to develop a technique for the volumetric reconstruction of chimerasimulation results. We propose an innovative method that allows us to build a collection of non-overlapping grids while preserving the main properties of the former simulation grids and featuring boundary conforming property everywhere.The theorical complexity of our algorithms has proved to be linear in the size of the former grids and leads to computation times of a few seconds for grids of hundreds of thousands of cells. The main impact of this work leads in the possibility of using any post-processing tool, including a large number of OpenSource solutions, for post-processing chimera simulation results, which is a mandatory condition for the wide acceptance of this method by industry actors
Yang, Kuan. "Ancestral Genome Reconstruction in Bacteria." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/28091.
Повний текст джерелаPh. D.
Chang, Ka Kit. "Human model reconstruction from image sequence /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?MECH%202003%20CHANG.
Повний текст джерелаIncludes bibliographical references (leaves 124-134). Also available in electronic version. Access restricted to campus users.
Talukdar, Saifulla. "Ekofisk Chalk: Core Measurements, Stochastic Reconstruction, Network Modeling and Simulation." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-120.
Повний текст джерелаThis dissertation deals with (1) experimental measurements on petrophysical reservoir engineering and morphological properties of Ekofisk chalk, (2) numerical simulation of core flood experiments to analyze and improve relative permeability data, (3) stochastic reconstruction of chalk samples from limited morphological information, (4) extraction of pore space parameters from the reconstructed samples, development of network model using pore space information, and computation of petrophysical and reservoir engineering properties from network model, and (5) development of 2D and 3D idealized fractured reservoir models and verification of the applicability of several widely used conventional upscaling techniques in fractured reservoir simulation.
Experiments have been conducted on eight Ekofisk chalk samples and porosity, absolute permeability, formation factor, and oil-water relative permeability, capillary pressure and resistivity index are measured at laboratory conditions. Mercury porosimetry data and backscatter scanning electron microscope images have also been acquired for the samples.
A numerical simulation technique involving history matching of the production profits is employed to improve the relative permeability curves and to analyze hysteresis of the Ekofisk chalk sample. The technique was found to be a powerful tool to supplement the uncertainties in experimental measurements.
Porosity and correlation statistics obtained from backscatter scanning electron microscope image are used to reconstruct microstructures of chalk and particulate media. The reconstruction technique involves a simulated annealing algorithm, which can be constrained by an arbitrary number of morphological parameters. This flexibility of the algorithm is exploited to successfully reconstruct particulate media and chalk samples using more that one correlation function. A technique based on conditional simulated annealing has been introduced for exact reproduction of vuggy porosity in chalk in the form of foraminifer shells. A hybrid reconstruction technique that initialized the simulated annealing reconstruction with input generated using the Gaussian random field model has also been introduced. The technique was found to accelerate significantly the rate of convergence of the simulated annealing method. This finding is important because the main advantage of the simulated annealing method, namely its ability to impose a variety of reconstruction constraints, is usually compromised by its very slow rate of convergence.
Absolutely permeability, formation factor and mercury-air capillary pressure are computed from simple network models. The input parameters for the network models were extracted from a reconstructed chalk sample. The computed permeability, formation factor and mercury-air capillary pressure correspond well with the experimental data. The predictive power of a network model for chalk is further extended through incorporating important pore-level displacement phenomena and realistic description of pore space geometry and topology. Limited results show that the model may be used to compute absolute and relative permeabilities, capillary pressure, formation factor, resistivity index and saturation exponent. The above findings suggest that the network modeling technique may be used for prediction of petrophysical and reservoir engineering properties of chalk. Further works are necessary and an outline is given with considerable details.
Two 2D, one 3D and a dual-porosity fractured reservoir models have been developed and an imbibition process involving water displacing oil is simulated at various injection rates and with different oil-to-water viscosity ratios using four widely used conventional upscaling techniques. The upscaling techniques are the Kyte & Berry, Pore Volume Weighted, Weighed Relative Permeability, and Stone. The results suggest that the upscaling of fractured reservoirs may be possible using the conventional techniques. Kyte & Berry technique was found to be the most effective in all situations. However, further investigations are necessary using realistic description of fracture length, orientation, connectivity, aperture, spacing, etc.
Paper 3,4 and 5 reprinted with kind persmission of Elsevier Science, Science Direct.
Grandi, Massimiliano <1970>. "Microwave Breast Cancer Imaging: Simulation, Experimental Data, Reconstruction and Classification." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7276/1/GRANDI_MASSIMILIANO_TESI.pdf.
Повний текст джерелаYue, Jinlong. "L'élastographie par résonance magnétique et l'élastographie ultrasonore par ondes de cisaillement supersonic : simulation, comparaison expérimentale et l'application pour la caractérisation du foie." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS483/document.
Повний текст джерелаElastography is an emerging medical imaging modality which permits to measure the mechanical properties of human soft tissue. The measured mechanical properties can serve as potential biomarkers for improving the management of diseases, from early diagnosis, to severity evaluation and therapy response monitoring. Among different approaches, Magnetic Resonance Elastography (MRE) and Supersonic Shear Imaging (SSI) have shown particular interests. The two modalities have been widely investigated for multiple clinical applications. However, each modality is challenged by specific acquisition and reconstruction conditions which may induce intra- and inter-modality measurement biases and hence impede the interchangeability of the two modalities. The first part of my thesis focused on identifying the measurement biases between MRE and SSI. Through a thorough methodological comparison study, we recognized different frequency characteristics of generated shear waves for the two modalities and modality specific reconstruction validity issues as the main sources for the measurement biases between the two modalities. Then through a dedicated simulation study, we established an in silico abaci to identify the favorable range of number of voxels per wavelength which leads to accurate and precise MRE. Moreover, resampling was proven effective to regulate poorly defined number of voxels per wavelength to the favorable range. The overall outcome, which is usually computed from the three acquired motionencoded directions, may further be improved by appropriate weighting strategies that are based on curl of shear displacement field. For SSI, we referred to the quality parameter provided by the manufacturer to reasonably eliminate unreliable results so as to further improve the measurement quality. After establishing the potential measurement biases between MRE and SSI, we incorporated the proposed quality optimization strategies into both modalities in order to perform unbiased experimental comparison studies between the two modalities. First, in vitro studies were carried out on commercial calibrated phantoms as well as home-made polyvinyl alcohol phantoms. Experimental results corroborate well the simulation findings. MRE and SSI measurements agree well witheach other when theory, experiment, and reconstruction biases are minimized. In vivo studies were then performed on the livers of two healthy volunteers. We found that when the liver is quasi-elastic, the quality-guided MRE and SSI measurements agree well with each other and hence are interchangeable. In case of viscoelastic liver tissue, both MRE and SSI measurements are frequency dependent. Thus frequency-specific measurements are essential for cross-validating the measurements of these two modalities
Ruiz, Fernández Guillermo. "3D reconstruction for plastic surgery simulation based on statistical shape models." Doctoral thesis, Universitat Pompeu Fabra, 2018. http://hdl.handle.net/10803/667049.
Повний текст джерелаAquesta tesi ha estat realitzada a Crisalix amb la col·laboració de la Universitat Pompeu Fabra sota el pla de Doctorats Industrials. Crisalix té com a objectiu la millora de la comunicació entre els professionals de la cirurgia plàstica i els pacients, proporcionant una solució a la pregunta que sorgeix més freqüentment durant el procés de planificació d'una operació quirúrgica ``Com em veuré després de la cirurgia?''. La solució proposada per Crisalix està basada en la tecnologia d'imatge 3D. Aquesta tecnologia genera la reconstrucció 3D de la zona del pacient operada, seguit de la possibilitat de crear múltiples simulacions obtenint la representació dels possibles resultats de la cirurgia. Aquesta tesi presenta un sistema capaç de reconstruir cares i pits de pacients de cirurgia plàstica a partir de fotos 2D i escanegis. La reconstrucció en 3D d'un objecte és un problema complicat degut a la presència d'ambigüitats. Els mètodes basats en models estadístics son adequats per mitigar-les. En aquest treball, hem seguit la intuïció de maximitzar l'ús d'informació prèvia, introduint-la al model estadístic per millorar les seves propietats. En primer lloc, explorem els Active Shape Models (ASM) que són un conegut mètode fet servir per alinear contorns d'objectes 2D. No obstant, un cop aplicades les correccions de forma del model estadístic, es difícil de mantenir informació de la que es disposava a priori (per exemple, un petit conjunt de punts donat) inalterada. Proposem una nova projecció ponderada amb un terme de regularització, que permet obtenir formes que compleixen les restriccions de forma imposades i alhora són plausibles en concordança amb el model estadístic. En segon lloc, ampliem la metodologia per aplicar-la als anomenats 3D Morphable Models (3DMM) que són un mètode extensivament utilitzat per fer reconstrucció 3D. No obstant, els mètodes de 3DMM existents presenten algunes limitacions. Alguns estan basats en optimitzacions no lineals, computacionalment costoses i que poden quedar atrapades en mínims locals. Una altra limitació, és que no tots el mètodes proporcionen la resolució adequada per representar amb precisió els detalls de l'anatomia. Donat l'ús mèdic de l'aplicació, la precisió i la robustesa són factors molt importants a tenir en compte. Mostrem com la inicialització i l'ajustament de 3DMM poden ser millorats fent servir la projecció ponderada amb regularització proposada. Finalment, es presenta un sistema capaç de reconstruir models 3D de pacients de cirurgia plàstica a partir de dos possibles tipus de dades: imatges 2D i escaneigs en 3D. El nostre mètode es fa servir en diverses etapes del procés de reconstrucció: alineament de formes en imatge, la inicialització i l'ajustament de 3DMM. Els mètodes desenvolupats han estat integrats a l'entorn de producció de Crisalix provant la seva validesa.
Perchet, Diane. "Modélisation in-silico des voies aériennes : reconstruction morphologique et simulation fonctionnelle." Phd thesis, Université René Descartes - Paris V, 2005. http://tel.archives-ouvertes.fr/tel-00273244.
Повний текст джерелаDans ce contexte, le projet RNTS RMOD a pour objectif de développer un simulateur morpho-fonctionnel des voies respiratoires pour l'aide au diagnostic, au geste médico-chirurgical et à l'administration de médicaments par inhalation.
Contribuant au projet RMOD, la recherche développée dans cette thèse propose une modélisation in-silico de la structure des voies aériennes supérieures (VAS) et proximales (VAP) à partir d'examens tomodensitométriques (TDM). L'investigation morphologique et la simulation fonctionnelle bénéficient alors de géométries 3D réelles, adaptées au patient et spécifiques des pathologies rencontrées.
La modélisation développée fait coopérer des méthodes originales de segmentation, de construction de surface maillée et d'analyse morpho-fonctionnelle.
La segmentation des VAP est obtenue par un schéma diffusif et agrégatif gouverné par un modèle markovien, dont l'initialisation repose sur l'opérateur de coût de connexion sous contrainte topographique. De cette segmentation, l'axe central de l'arbre bronchique est extrait de manière robuste et précise en combinant information de distance, propagation de fronts, et partition conditionnelle locale. Cet axe central est représenté sous forme d'une structure hiérarchique multivaluée synthétisant caractéristiques topologiques et géométriques de l'arbre bronchique. Une surface maillée est ensuite construite en appliquant une procédure de Marching Cubes adaptative, les paramètres des différents filtres mis en jeu étant automatiquement ajustés aux caractéristiques locales du réseau bronchique conditionnellement aux attributs de l'axe central.
La segmentation des VAS repose sur une propagation markovienne exploitant les variations locales de densité. L'initialisation combine morphologie mathématique et information de contour afin de garantir la robustesse à la topologie. Une procédure de type triangulation de Delaunay restreinte à une surface fournit ensuite la représentation maillée des VAS. Il est établi que la topologie et la géométrie des structures complexes composant les VAS sont effectivement préservées.
Pour permettre aux médecins de valider les modèles maillés ainsi construits, un environnement virtuel 3D convivial et interactif a été réalisé. En outre, la morphologie des voies aériennes exo- et endo-luminale est analysée de façon automatique à partir de simulations d'écoulement pour des géométries réelles.
Enfin, une modélisation unifiée des VAP et VAS est obtenue pour la première fois. Elle démontre la pertinence des approches développées. Elle ouvre la voie à la construction de modèles in-silico complets de l'appareil respiratoire ainsi qu'aux études fonctionnelles prenant en compte les paramètres morphologiques susceptibles d'influer localement ou globalement sur la dynamique des écoulements.
Zhao, Qiang. "Multi-model based simulation in the reconstruction of road traffic accident." Thesis, Loughborough University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.500371.
Повний текст джерелаRichard, Sébastien. "Reconstruction géométrique de la cornée par vidéokératographie." Aix-Marseille 3, 2005. http://www.theses.fr/2005AIX30040.
Повний текст джерелаThe goal is to rebuild in 3D the cornea starting from a digital image computed by videokeratography. Image is generated by illuminating a specularly reflective surface with a pattern of light with concentric rings, and captured by a camera video. Until now, algorithms used by videokeratographs are sometimes inaccurate. So we have developed a new methodology based on an ascending-descending analysis process. The ascending phase is based on the simulation of the videokeratography by backward ray tracing, and consists in rebuild the cornea starting from data resulting from a segmentation of the digital image. The result obtained is an approximate but robust solution. The descending phase is based on forward ray tracing, and consists in fitting the approximate model directly on digital image. One will thus obtains an accurate model representative of the patient's cornea
Madec, Morgan. "Conception, Simulation et Realisation d'un processeur optoélectronique pour la reconstruction d'images médicales." Phd thesis, Université Louis Pasteur - Strasbourg I, 2006. http://tel.archives-ouvertes.fr/tel-00166879.
Повний текст джерелаABDULMASSIH, DIOGO SOARES. "RIGID GROUND VEHICLES MODELS FOR COLLISIONS ANALYSIS AND SIMULATION AND ACCIDENTS RECONSTRUCTION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5101@1.
Повний текст джерелаApresentam-se nesta dissertação os principais modelos para análise e simulação de colisões e reconstituição de acidentes, desenvolvidos especialmente para reproduzir a dinâmica de uma colisão de forma adequada. Esse tipo de tratamento está se tornando uma indispensável ferramenta de auxílio nas perícias judiciais e para uma melhor interpretação de problemas de colisão em geral. Os programas desenvolvidos em MATLAB são baseados na implementação das equações relacionadas à interação entre os veículos, supostos rígidos, que ocorre durante uma colisão e são aplicáveis aos casos de colisões centrais e oblíquas, gerando resultados válidos e compatíveis aqueles obtidos através da teoria de conservação da quantidade de movimento, e com as medições realizadas após os acidentes.
It is shown in this dissertation the main models for collisions analysis and simulation and accidents reconstruction, developed specially to reproduce the collision dynamics by an appropriated approach. This approach are becoming an indispensable tool of help for a better interpretation of collision and forensic problems. The MATLAB programs developed are based on implementation of equations related to rigid vehicles interaction in a collision, and are applicable for the central and oblique collisions, supplying valid and compatible results to those obtained by momentum conservation theory, and accidents experimental data.
Madec, Morgan. "Conception, simulation et réalisation d’un processeur optoélectronique pour la reconstruction d’images médicales." Université Louis Pasteur (Strasbourg) (1971-2008), 2006. https://publication-theses.unistra.fr/public/theses_doctorat/2006/MADEC_Morgan_2006.pdf.
Повний текст джерелаOptical processing can be used to speed up some algorithms of image reconstruction from tomodensitometric data provided by volume exploration systems. This may be of high interest in order to meet the needs of future assisted therapy systems. Two systems are described in this document, corresponding to the two main steps of the above mentioned algorithms: a filtering processor and a backprojection processor. They are first considered under a material point of view. Whatever function it may compute, an optical processor is made up of light sources, displays and cameras. Present state-of-the-art devices highlight a weakness in display performances. Special attention has been focused on ferroelectric liquid crystal spatial light modulators (modelling, simulations, and characterizations of commercial solutions). The potential of optical architectures is compared with electronic solutions, considering computation power and processed image quality. This study has been carried out for both systems first in simulation, with a reliable model of the architecture, and then with an experimental prototype. The optical filtering processor does not give accurate results: the signal to noise ratio on the reconstructed image is about 20 dB in simulation (the model used does not take into account the majority of geometrical distortions) and experimental measurements show strong limitation, especially when considering the problem of image formation with coherent lighting (speckle). On the other hand, results obtained with the optical backprojection processor are most encouraging. The model, more complete and accurate than the filtering processor, as well as the simulations, shows that processed image quality can be virtually equivalent to the one obtained by digital means (signal to noise ratio is over 50 dB) with two order of magnitude speed-up. Results obtained with the experimental prototype are in accordance with simulations and confirm the potential held by the architecture. As an extension, a hybrid processor involving the backprojection processor for the computation of more complex reconstruction algorithms, e. G. ASSR for helical CT-scan, is proposed in the last part of the document
Rajaram, Ramya Zhou Otto. "A stationary digital breast tomosynthesis system design simulation, characterization and image reconstruction /." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2009. http://dc.lib.unc.edu/u?/etd,2541.
Повний текст джерелаTitle from electronic title page (viewed Oct. 5, 2009). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Curriculum of Applied Sciences and Engineering." Discipline: Applied and Materials Sciences; Department/School: Applied and Materials Sciences.
Madec, Morgan Hervé Yannick. "Conception, simulation et réalisation d'un processeur optoélectronique pour la reconstruction d'images médicales." Strasbourg : Université Louis Pasteur, 2007. http://eprints-scd-ulp.u-strasbg.fr:8080/630/01/madec2006.pdf.
Повний текст джерелаMunsch, Marie. "Élaboration d’une méthodologie de reconstruction numérique d’accidents réels piéton." Strasbourg, 2011. https://publication-theses.unistra.fr/public/theses_doctorat/2011/MUNSCH_Marie_2011.pdf.
Повний текст джерелаPedestrians are considered the most vulnerable road users and alone account for 13% of killed in road accidents in France. For several years, to improve pedestrian safety, the first step was to understand the relationship between vehicle design and mechanisms of pedestrian injuries. Mathematical multibody models of pedestrians and vehicles have been developed to simulate the kinematics of the victim during impact with the vehicle. These are the modeling efforts that should lead to the definition of the initial conditions of the head at impact for the simulation of head injury using a finite element modeling. In this context, the objective is to develop a methodology for the reconstruction of real pedestrian accident to determine its kinematics and to simulate the head injury. This last step will ultimately extract head injury criteria more accurate than the criteria currently used. It is thus necessary to define mathematical models of vehicle and pedestrian. An evaluation of different models of multibody neck models and head boundary conditions was performed using a multi-modal analysis. Then the thesis will be on developing an automated method of reconstruction of the pedestrian kinematics with multibody modeling. An application of the developed tool is performed on a database of 8 real accidents of pedestrian vs. Vehicle
Tsang, Kin Ting. "Interactive 3D model reconstruction from images and quasi-dense points /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?COMP%202004%20TSANG.
Повний текст джерелаIncludes bibliographical references (leaves 59-62). Also available in electronic version. Access restricted to campus users.
Hilaire, Estelle. "Simulation et reconstruction 3D à partir de caméra Compton pour l’hadronthérapie : Influence des paramètres d’acquisition." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0104/document.
Повний текст джерелаHadrontherapy is a cancer treatment method which uses ions (proton or carbon) instead of X-rays. Interactions between the beam and the patient produce secondary radiation. It has been shown that there is a correlation between the emission position of some of these particles and the Bragg peak position. Among these particles, prompt-gamma are produced by excited nuclear fragments and current work aims to design SPECT systems able to image the emission position the radiation in real time, with a millimetric precision, despite the low data statistic. Although it is not currently possible, the goal is to monitor the deposited dose. The Compton camera is a SPECT system that proposed for imaging such particles, because it offers a good energy resolution and the possibility of a 3D imaging. However, in practice the acquisition is affected by noise from other secondary particles and the reconstruction algorithms are more complex and not totally completed, but the developments are well advanced. In this thesis, we developed a complete process from the simulation of irradiation of a phantom by a proton beam up to the tomographic reconstruction of images obtained from data acquired by the Compton camera. We studied different reconstruction methods (analytical and iterative), and we have developed an iterative method able to consider the measurement uncertainties on energy. Finally we developed methods to detect the end-of-range of the reconstructed prompt-gamma distributions
Amrani, Morade. "Modélisation et simulation d'objets déformables." Lyon 1, 2002. http://www.theses.fr/2002LYO10256.
Повний текст джерелаYureidini, Ahmed. "Robust blood vessel reconstruction for interactive medical simulations." Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10044/document.
Повний текст джерелаIn the context of interactive simulation, the lack of patient specific geometrical models remains one of the major limitations of simulators. Current commercial simulators proposed no or a limited number of cases. However, a vast literature on the subject has been introduced in the past twenty years. Nevertheless, the proposed methods are not adapted to an interactive context, especially when dealing with vascular networks. In this work, we address the problem of blood vessel segmentation and reconstruction from 3DRA patient data. To this end, we propose two novel algorithms for segmentation and reconstruction. First, the vessel tree is built by tracking the vessel centerline. Our dedicated tracking process also extracts points on the vessel surface in a robust way. Second, those points are fitted by an implicit surface (a blobby model) that is iteratively refined. Tracking and reconstruction results are reported on synthetic and patient data. Simulations within an interventional tool navigation context showed that the resulting geometrical model complies with interactive simulation requirements : fast collision detection and prediction, topology information, smoothness and availability of differential quantities for contact response computation
Khellaf, Feriel. "List-mode proton CT reconstruction." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI074.
Повний текст джерелаProton therapy is used for cancer treatment to achieve better dose conformity by exploiting the energy-loss properties of protons. Proton treatment planning systems require knowledge of the stopping-power map of the patient’s anatomy to compute the absorbed dose. In clinical practice, this map is generated through a conversion from X-ray computed tomography (CT) Hounsfield units to proton stopping power relative to water (RSP). This calibration generates uncertainties as photon and proton physics are different, which leads to the use of safety margins and the reduction of dose conformity. In order to reduce uncertainties, proton CT (pCT) was proposed as a planning imaging modality since the reconstructed quantity is directly the RSP. In addition to energy loss, protons also undergo multiple Coulomb scattering (MCS) inducing non-linear paths, thus making the pCT reconstruction problem different from that of X-ray CT. The objective of this thesis is to improve image quality of pCT list-mode reconstruction. The use of a most likely path (MLP) formalism for protons to account for the effects of MCS has improved the spatial resolution in pCT. This formalism assumes a homogeneous medium. The first contribution of this thesis is a study on proton paths in heteregeneous media: the accuracy of the MLP was evaluated against a Monte Carlo generated path in different heterogeneous configurations. Results in terms of spatial, angular, and energy distributions were analyzed to assess the impact on reconstruction. The second contribution is a 2D directional ramp filter used for pCT data reconstruction. An intermediate between a filtered backprojection and a backproject-filter approach was proposed, based on the extension of the usual ramp filter to two dimensions, in order to preserve the MLP spatial information. An expression for a band-limited 2D version of the ramp filter was derived and tested on simulated pCT list-mode data. Then, a comparison of direct reconstruction algorithms in terms of spatial resolution and RSP accuracy was conducted. Five algorithms, including the 2D directional ramp, were tested to reconstruct different simulated phantoms. Results were compared between reconstruction from data acquired using idealized or realistic trackers. Finally, the last contribution is a deconvolution method using the information on the MLP uncertainty in order to improve spatial resolution of pCT images
CARVALHO, FABIO VINICIUS MOURA DE. "FLEXIBLE VEHICLES MODELS FOR THE ANALYSIS AND SIMULATION OF COLLISIONS AND ACCIDENT RECONSTRUCTION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5134@1.
Повний текст джерелаA procedure for the simulation of flexible ground vehicles collisions is presented, which uses the conditions at the instant just before the impact as input variables and the evolution of the dynamic variables during the collision as output. Various simulations are presented and compared to similar cases found in the literature, what validates the proposed models. The algorithm was implemented using Simulink/Matlab software and used the same structure of the other programs under development in this area, in order to integrate it to graphic pre-processors and post-processors available in SVDV program - Simulation and Visualization of Vehicle Dynamics.
Wang, Junjie. "Numerical simulation of corneal refractive surgery based on improved reconstruction of corneal surface." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3000347/.
Повний текст джерелаAllan, Gregory W. (Gregory William). "Simulation and testing of wavefront reconstruction algorithms for the deformable mirror (DeMi) cubesat." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120381.
Повний текст джерелаThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 93-98).
The search for exoplanets has discovered thousands of worlds orbiting stars other than our own. To learn more about these worlds, it is necessary to directly image them and study their atmospheric spectra. Especially of interest are Earth-like planets, but they are typically outshined by their host stars by a factor of 10₁₀, meaning high-contrast imaging is required to see them. Coronagraphs are typically used to block the starlight to achieve high contrast, but atmospheric, thermal, and mechanical aberrations can cause spurious speckles of starlight to contaminate the image. Use of space telescopes removes atmospheric aberrations, but other sources still remain. In order to achieve the optical performance necessary for high-contrast imaging, adaptive optics (AO) techniques in space are needed. High actuator count deformable mirrors (DMs) used in an AO system enable the required contrasts across sufficient fields of view, but typically have high size, weight, and power requirements, and can be complex to implement. New technologies such as Micro-electromechanical Systems (MEMS) DMs can potentially alleviate these problems. MEMS DMs also have applications in high-energy lasers, optical communications, and imaging systems. However, MEMS DMs have not been sufficiently tested in an orbital environment. While environmental tests can be performed on the ground, on-orbit operation in vacuum with exposure to radiation for extended periods cannot be sufficiently simulated. If MEMS DMs are to gain acceptance for use in future space missions, interactions with other system components must be studied, and support systems suitable for operating the DM in the space environment with constrained size, power, and computation resources must be developed. This thesis discusses the Deformable Mirror Demonstration Mission (DeMi), which aims to address these needs. Specifically, we develop and demonstrate wavefront sensing approaches suitable for demonstrating and characterizing a MEMS DM on a small satellite platform.
by Gregory W. Allan.
S.M.
Papadopoulos, Konstantinos. "Knowledge production through the process of digital reconstruction : simulation of Greek neolithic space." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/366597/.
Повний текст джерелаLin, Yixin. "A Local Surface Reconstruction Algorithm for Surface Tension Simulation in Smoothed Particle Hydrodynamics." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613752656589083.
Повний текст джерелаAtkin, Ryan Justin. "Simulation of the ATLAS ITk strip endcap modules for testbeam reconstruction and analysis." Master's thesis, Faculty of Science, 2019. http://hdl.handle.net/11427/31148.
Повний текст джерелаWestling, Fredrik Anders. "Pruning of Tree Crops through 3D Reconstruction and Light Simulation using Mobile LiDAR." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/27427.
Повний текст джерелаChandramouli, Pranav. "Turbulent complex flows reconstruction via data assimilation in large eddy models." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1S035/document.
Повний текст джерелаData assimilation as a tool for fluid mechanics has grown exponentially over the last few decades. The ability to combine accurate but partial measurements with a complete dynamical model is invaluable and has numerous applications to fields ranging from aerodynamics, geophysics, and internal ventilation. However, its utility remains limited due to the restrictive requirements for performing data assimilation in the form of computing power, memory, and prior information. This thesis attempts at redressing various limitations of the assimilation procedure in order to facilitate its wider use in fluid mechanics. A major roadblock for data assimilation is the computational cost which is restrictive for all but the simplest of flows. Following along the lines of Joseph Smagorinsky, turbulence modelling through large-eddy simulation is incorporated in to the assimilation procedure to significantly reduce computing power and time required. The requirement for prior volumetric information for assimilation is tackled using a novel reconstruction methodology developed and assessed in this thesis. The snapshot optimisation algorithm reconstructs 3D fields from 2D cross- planar observations by exploiting directional homogeneity. The method and its variants work well with synthetic and experimental data-sets providing accurate reconstructions. The reconstruction methodology also provides the means to estimate the background covariance matrix which is essential for an efficient assimilation algorithm. All the ingredients are combined to perform variational data assimilation of a turbulent wake flow around a cylinder successfully at a transitional Reynolds number. The assimilation algorithm is validated with synthetic volumetric observation and assessed on 2D cross-planar observations emulating experimental data
Walck, Guillaume. "Reconstruction 3D automatique d'objets inconnus en vue d'actions de saisie et manipulation." Paris 6, 2010. http://www.theses.fr/2010PA066251.
Повний текст джерелаROSSI, MARCO. "DEEP LEARNING APPLICATIONS TO PARTICLE PHYSICS: FROM MONTE CARLO SIMULATION ACCELERATION TO PROTODUNE RECONSTRUCTION." Doctoral thesis, Università degli Studi di Milano, 2023. https://hdl.handle.net/2434/951789.
Повний текст джерелаBonfort, Thomas. "Reconstruction de Surfaces Réfléchissantes à partir d'Images." Phd thesis, Grenoble INPG, 2006. http://tel.archives-ouvertes.fr/tel-00083540.
Повний текст джерелаTarsha, Kurdi Fayez. "Extraction et reconstruction de bâtiments en 3D à partir de relevés lidar aéroportés." Université Louis Pasteur (Strasbourg) (1971-2008), 2008. https://publication-theses.unistra.fr/public/theses_doctorat/2008/TARSHA_KURDI_Fayez_2008.pdf.
Повний текст джерелаIn order to construct automatically a 3D city model from lidar data, two steps are essential. The first one is the automatic segmentation of the point cloud into three mean classes (terrain, vegetation and buildings). Once the buildings are detected, the automatic building construction can start. The proposed approach achieves automatically the segmentation task into two stages. The first one is the segmentation of the Digital Surface Model (DSM) into two classes which are terrain and off-terrain. For this purpose, a local thresholding is applied through a convolution operator. This operation allows to separate the two classes even in rugged topography areas. The second step is the automatic building detection from the off-terrain class. At this stage, the DSM and the point cloud are used together in order to take advantage of each one. For automatic modelling of buildings, the proposed approach consists of three phases: buildings facade modelling by detection and segmentation of building outline polygons, construction of 2D roof model starting from the automatic detection of roof planes and finally, the total 3D building model is calculated by analysing the mutual relationships between adjacent roof planes. The technique RANSAC (Random Sample Consensus) has been extended and applied to detect automatically the roof planes. Finally the detection of roof planes, borders and nodes allows to construct the 3D building model
Bidal, Samuel. "Reconstruction tridimensionnelle d'éléments anatomiques et génération automatique de maillage éléments finis optimisés." Phd thesis, Université de la Méditerranée - Aix-Marseille II, 2003. http://tel.archives-ouvertes.fr/tel-00545018.
Повний текст джерелаYang, Guanyu. "Environnement de simulation pour l'évaluation des algorithmes de reconstruction 3D en angiographie rotationnelle R-X." Rennes 1, 2008. http://www.theses.fr/2008REN1S173.
Повний текст джерелаWe propose a simulation environment for the evaluation of 3D coronary tree reconstruction algorithms in rotational angiography. It includes the construction of a 3D dynamic model of the coronary tree from a dynamic sequence of volumes acquired on a multi-slice computed tomography angiography system (volumes reconstructed every 10% of the cardiac cycle), the modelling of the rotational angiography acquisition system to simulate different acquisition and gating strategies and the calculation of radiographic projections of the 3D model of coronary tree throughout several cardiac cycles
Bouchard-Gilanton, Véronique. "Modélisation et correction de l'effet Compton dans la reconstruction d'images tomoscintigraphiques." Grenoble 1, 1997. http://www.theses.fr/1997GRE10003.
Повний текст джерелаCalvez, Steven. "Development of reconstruction tools and sensitivity of the SuperNEMO demonstrator." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS285/document.
Повний текст джерелаSuperNEMO is an experiment looking for the neutrinoless double beta decay in an effort to unveil the Majorana nature of the neutrino. The first module, called the demonstrator, is under construction and commissioning in the Laboratoire Souterrain de Modane. Its unique design combines tracking and calorimetry techniques. The demonstrator can study 7 kg of ⁸²Se, shaped in thin source foils. These source foils are surrounded by a wire chamber, thus allowing a 3-dimensional reconstruction of the charged particles tracks. The individual particles energies are then measured by a segmented calorimeter, composed of plastic scintillators coupled with photomultipliers. A magnetic field can be applied to the tracking volume in order to identify the charge of the particles. SuperNEMO is thus able to perform a full reconstruction of the events kinematics and to identify the nature of the particles involved: electrons, positrons, α particles or γ particles. In practice, the particle and event reconstruction relies on a variety of algorithms, implemented in the dedicated SuperNEMO simulation and reconstruction software. The γ reconstruction is particularly challenging since γ particles do not leave tracks in the wire chamber and are only detected by the calorimeter, sometimes multiple times. Several γ reconstruction approaches were explored during this thesis. This work lead to the creation of a new algorithm optimizing the γ reconstruction efficiency and improving the γ energy reconstruction. Other programs allowing the particle identification and performing the topological measurements relevant to an event were also developed. The value of the magnetic field was optimized for the 0νββ decay search, based on Monte-Carlo simulations. The magnetic shieldings performances and their impact on the shape of the magnetic field were estimated with measurements performed on small scale magnetic coils. The SuperNEMO demonstrator is able to measure its own background contamination thanks to dedicated analysis channels. At the end of the first 2.5 years data taking phase, the main backgrounds target activities should be measured accurately. The ⁸²Se 2νββ half-life should be known with a 0.3 % total uncertainty. Unlike other double beta decay experiments relying solely on the two electrons energy sum, SuperNEMO has access to the full events kinematics and thus to more topological information. A multivariate analysis based on Boosted Decision Trees was shown to guarantee at least a 10 % increase of the sensitivity of the 0νββ decay search. After 2.5 years, and if no excess of 0νββ events is observed, the SuperNEMO demonstrator should be able to set a limit on the 0νββ half-life of T > 5.85 10²⁴ y, translating into a limit on the effective Majorana neutrino mass mββ < 0.2 − 0.55 eV. Extrapolating this result to the full-scale SuperNEMO experiment, i.e. 500 kg.y, the sensitivity would be raised to T > 10²⁶ y or mββ < 40 − 110 meV
Haouchine, Nazim. "Image-guided simulation for augmented reality during hepatic surgery." Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10009/document.
Повний текст джерелаThe main objective of this thesis is to provide surgeons with tools for pre and intra-operative decision support during minimally invasive hepatic surgery. These interventions are usually based on laparoscopic techniques or, more recently, flexible endoscopy. During such operations, the surgeon tries to remove a significant number of liver tumors while preserving the functional role of the liver. This involves defining an optimal hepatectomy, i.e. ensuring that the volume of post-operative liver is at least at 55% of the original liver and the preserving at hepatic vasculature. Although intervention planning can now be considered on the basis of preoperative patient-specific, significant movements of the liver and its deformations during surgery data make this very difficult to use planning in practice. The work proposed in this thesis aims to provide augmented reality tools to be used in intra-operative conditions in order to visualize the position of tumors and hepatic vascular networks at any time
Soiné, Jérôme Roger Dennis [Verfasser], and Ulrich S. [Akademischer Betreuer] Schwarz. "Reconstruction and Simulation of Cellular Traction Forces / Jérôme Roger Dennis Soiné ; Betreuer: Ulrich S. Schwarz." Heidelberg : Universitätsbibliothek Heidelberg, 2014. http://d-nb.info/1179924827/34.
Повний текст джерелаSoiné, Jérôme [Verfasser], and Ulrich S. [Akademischer Betreuer] Schwarz. "Reconstruction and Simulation of Cellular Traction Forces / Jérôme Roger Dennis Soiné ; Betreuer: Ulrich S. Schwarz." Heidelberg : Universitätsbibliothek Heidelberg, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:16-heidok-168694.
Повний текст джерелаDelestre, Olivier. "Simulation du ruissellement d'eau de pluie sur des surfaces agricoles." Phd thesis, Université d'Orléans, 2010. http://tel.archives-ouvertes.fr/tel-00587197.
Повний текст джерелаWeber, Loriane. "Iterative tomographic X-Ray phase reconstruction." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI085/document.
Повний текст джерелаPhase contrast imaging has been of growing interest in the biomedical field, since it provides an enhanced contrast compared to attenuation-based imaging. Actually, the phase shift of the incoming X-ray beam induced by an object can be up to three orders of magnitude higher than its attenuation, particularly for soft tissues in the imaging energy range. Phase contrast can be, among others existing techniques, achieved by letting a coherent X-ray beam freely propagate after the sample. In this case, the obtained and recorded signals can be modeled as Fresnel diffraction patterns. The challenge of quantitative phase imaging is to retrieve, from these diffraction patterns, both the attenuation and the phase information of the imaged object, quantities that are non-linearly entangled in the recorded signal. In this work we consider developments and applications of X-ray phase micro and nano-CT. First, we investigated the reconstruction of seeded bone scaffolds using sed multiple distance phase acquisitions. Phase retrieval is here performed using the mixed approach, based on a linearization of the contrast model, and followed by filtered-back projection. We implemented an automatic version of the phase reconstruction process, to allow for the reconstruction of large sets of samples. The method was applied to bone scaffold data in order to study the influence of different bone cells cultures on bone formation. Then, human bone samples were imaged using phase nano-CT, and the potential of phase nano-imaging to analyze the morphology of the lacuno-canalicular network is shown. We applied existing tools to further characterize the mineralization and the collagen orientation of these samples. Phase retrieval, however, is an ill-posed inverse problem. A general reconstruction method does not exist. Existing methods are either sensitive to low frequency noise, or put stringent requirements on the imaged object. Therefore, we considered the joint inverse problem of combining both phase retrieval and tomographic reconstruction. We proposed an innovative algorithm for this problem, which combines phase retrieval and tomographic reconstruction into a single iterative regularized loop, where a linear phase contrast model is coupled with an algebraic tomographic reconstruction algorithm. This algorithm is applied to numerical simulated data
Huet, Pauline. "Modélisation, simulation et quantification de lésions athéromateuses en tomographie par émission de positons." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112132/document.
Повний текст джерелаCardiovascular disease is the leading cause of death in western countries. New strategies and tools for diagnosis and therapeutic monitoring need to be developed to manage patients with atherosclerosis, which is one major cause of cardiovascular disease. Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) is a powerful imaging technique that can detect at early stages plaques prone to rupture. Yet, Partial Volume Effect (PVE), due to the small lesion dimensions (around 1 mm) with respect to the scanner spatial resolution (around 6 mm full width at half maximum), and statistical variations considerably challenge the precise characterization of plaques from PET images. An original model of atheromatous lesion parameterized by its dimensions and activity concentration, was developed. Thirty six Monte Carlo simulations of FDG-PET acquisitions were produced. Based on the simulations, we showed that the number of iterations in iterative reconstructions, the post filtering of reconstructed images and the quantification method in the Volume Of Interests (VOI) varied sharply in an analysis of the dedicated literature. Changes in one of these parameters only could induce variations by a factor of 1.5 to 4 in the quantitative index. Overall, inflammation remained largely underestimated (> 50% of the real uptake). We demonstrated that modeling the detector response could reduce the bias by 10% of its value in comparison to a standard OSEM recontruction and for an identical level of noise. In reconstructed images, we showed that the measured values depended not only on the real uptake but also on the lesion dimensions because of PVE. A minimum contrast of 4 with respect to blood activity was required for the lesion to be observable. Without PVE correction, the measured values exhibited a correlation with activity concentration but were much more correlated with the total uptake in the lesion. Applying a PVE correction leads to an activity estimate that was less sensitive to the geometry of the lesion. The corrected values were more correlated to the activity concentration and less correlated to the total activity. In conclusion, we showed that the total activity in inflammatory lesions could be assessed in FDG-PET images. This estimate did not require PVE correction. Tracer concentration estimates are largely biased due to PVE, and the bias can be reduced by measuring the maximum voxel in the lesion in images reconstructed with at least 80 iterations and by modeling the detector response. Explicit PVE correction is recommended to detect metabolic changes independent of geometric changes. An accurate estimation of plaque uptake will however require the intrinsic spatial resolution of PET scanners to be improved
Bondeau, Christine. "Etude d'images perturbées par la turbulence atmosphérique : simulation et restauration." Dijon, 1999. http://www.theses.fr/1999DIJOS076.
Повний текст джерелаSuggs, Jeremy F. (Jeremy Floyd) 1976. "Simulation of anterior cruciate ligament injury and reconstruction using a 3D finite element knee joint model." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/89369.
Повний текст джерелаPETRETTO, GUIDO. "Density functional simulation of chalcogen doped silicon nanowires." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2012. http://hdl.handle.net/10281/28938.
Повний текст джерела