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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Caractérisation des écoulements instationnaires 3D par tomographie holographique numérique multidirectionnelle / Characterization of 3D unsteady flows by multidirectional digital holographic tomography

Olchewsky, François 20 November 2017 (has links)
Ces travaux de thèse s'inscrivent dans le cadre du développement métrologique des méthodes optiques appliquées à la mécanique des fluides pour la caractérisation des phénomènes aérodynamiques complexes 2D et 3D. Parmi ces méthodes, l'holographie numérique donne accès à la phase de l'écoulement, grandeur directement reliée à l'intégration de l'indice de réfraction de l'écoulement, la masse volumique étant déduite par la relation de Gladstone-Dale. Si la mesure de la phase est effectuée suivant plusieurs directions de visée, la masse volumique de l'écoulement peut être reconstruite en 3D par tomographie. Après avoir développé l'holographie numérique à la mesure des forts gradients de masse volumique caractéristiques des essais en soufflerie, trois campagnes d'essais ont été effectuées sur des écoulements 3D stationnaires pour comparer les performances de l'holographie numérique par rapport à la strioscopie interférentielle et la Background Oriented Schlieren (BOS) qui donnent accès à la déviation lumineuse, l'intégration de la dérivée de l'indice. L'algorithme de reconstruction 3D développé par l'Onera/DMPE pour la BOS3D, basé sur la minimisation d'un critère des moindres carrés régularisé par Tikhonov par la méthode des gradients conjugués, a été adapté aux mesures de phase. Les reconstructions avec 36 visées ont été comparées aux reconstructions obtenues par strioscopie interférentielle et BOS. Enfin, l'analyse sur le nombre de visées nécessaires à la reconstruction a montré sa dépendance avec la complexité 3D du jet, ce qui a conduit à mettre en oeuvre un banc d'holographie numérique à six visées simultanées pour reconstruire avec succès des jets libres instationnaires. / This PhD work is part of the metrological development of optical methods applied to Fluid Mechanics to characterize 2D and 3D complex aerodynamic phenomenon. One of these techniques is digital holography which measures flow phase, directly linked to the refractive index integration. Gas density is deduced thanks to Gladstone-Dale relationship. If phase measurements are done along several viewpoints, gas density can be rebuilt in 3D by tomography. Firstly, digital holography was developed to measure high density gradients encountered in compressible wind tunnels. Then, three campaigns were made on steady 3D flows to compare performances of digital holography to differential interferometry and Background Oriented Schlieren (BOS) which measure light deviation, integration of the derivative of refractive index. 3D reconstruction algorithm developed by Onera/DMPE for 3DBOS, based on conjugated gradients method of a least squared regularized by Tikhonov minimization criterion, was adapted to phase measurements. Reconstructions with 36 different viewpoints were compared to reconstructions obtained by differential interferometry and BOS. Finally, the analysis of the viewpoint number needed to reconstruction showed its dependency with 3D complexity of the jet, what led to the implementation a digital holographic set-up with six simultaneous viewpoints to rebuild with success unsteady flows.
32

La reconstruction de l'État-Nation en Afghanistan / State and Nation-Building in Afghanistan

Mannani, Haroon 11 July 2014 (has links)
Le résumé en français n'a pas été communiqué par l'auteur. / Le résumé en anglais n'a pas été communiqué par l'auteur.
33

The surgical reconstruction of the anterior column in the management of the tuberculosis of the spine (Chris Hani Baragwanath academic hospital experience: 2012-2015)

Akinjolire, Akinwande January 2017 (has links)
A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, in partial fulfillment of the requirements for the degree of Master of Medicine in Orthopaedic Surgery Johannesburg, 2017 / Background: The anterolateral approach to the spine for the surgical management of the Tuberculosis of the spine has been described. The surgical technique has evolved since the gold standard published by Hodgson et al. in 1956. The use of a Titanium Mesh Cage and the anterior instrumentation to construct the anterior column after adequate debridement defined the evolution. The aim of the study is to review the results of the patients that underwent this procedure between January 2012 and December 2015. Methods: The study was a retrospective study where 60 patients treated with this technique from 2012 – 2015 were reviewed. Sixty-one percent (61%) of the tested patients were HIV positive and 70.4% of the patients were female in the age group of 31-45 years. The surgical procedure was standardised for all the patients irrespective of their HIV status. The clinical and radiological outcomes measured consisted of the patients’ disability using the Oswestry Disability Index (ODI), the Frankel Neurological grading to measure neurological deficits and the Cobb angle to measure Kyphosis. The diagnosis of Tuberculosis of the Spine was confirmed in all the patients. Results: At a mean follow up period of 21.25 months, the ODI improved from a mean of 95.42% ± 6.57% before surgery to a mean of 8.00% ± 12.15% at the last follow up. There were 58 patients who were unable to walk independently before the surgery (Frankel A or B) but at the last follow up, 52 of the patients had achieved independent ambulation (Frankel D or E). The mean kyphosis was 33.90 ± 12.44 degrees before surgery, and in the immediate post-operative period, the mean kyphosis was 23.69 ± 10.31 degrees, and a mean of 26.27 ± 10.91 degrees was measured at the last follow up. There was a 30.12% correction achieved in the immediate post-operative period and an overall correction of 22.51% at the last follow up reflecting a loss of 7.61% in the kyphosis correction in the period between the immediate post-operative period and the last follow up. Complications were documented in six patients including two deaths unrelated to the procedure. Discussion: The ODI score showed an improvement as the mean value decreased by 87.42%. This is statistically and clinically significant (p=0.001). According to the work of Solberg et al. (2013) in degenerative spine, the threshold for a success is a mean change of 20% in the ODI scoring after lumbar disc surgery. Using this value as a proxy, an improvement of 87.42% is an excellent outcome. Before surgery, fifty-eight patients (96.7%) were non-ambulatory using the Frankel Neurological score. At the last follow up, 53 patients (91.4%) achieved a Frankel score of D or E and independent ambulation. This outcome compares favourably with ones published in the literature. The overall post-operative kyphosis correction achieved was 26.27 degrees (which translated to 22.51% correction) at the last follow up. This reflects a kyphosis correction loss of 7.61% that was not associated with any neurological deterioration and is therefore of no clinical significance. There were six cases of complications including two deaths unrelated to the procedure but the general debilitation of military Tuberculosis and Nosocomial infection. Conclusion: The anterior column reconstruction using the Titanium Mesh Cage and Anterior Instrumentation is safe and effective for the surgical management of the Tuberculosis of the Spine. There were good clinical outcomes as measured by the ODI score and the Frankel Neurological Grading system, and even though there was a loss of Kyphosis correction at the last follow up, this was not associated with a negative neurological outcome. Despite its limitation as a retrospective study, this study demonstrates that the procedure is safe and effective when used as an adjunct to the medical treatment of the Tuberculosis of the Spine. / MT2017
34

3D model reconstruction with noise filtering using boundary edges.

January 2004 (has links)
Lau Tak Fu. / Thesis submitted in: October 2003. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 93-98). / Abstracts in English and Chinese. / Chapter 1 - --- Introduction --- p.9 / Chapter 1.1 --- Scope of the work --- p.9 / Chapter 1.2 --- Main contribution --- p.11 / Chapter 1.3 --- Outline of the thesis --- p.12 / Chapter 2 - --- Background --- p.14 / Chapter 2.1 --- Three dimensional models from images --- p.14 / Chapter 2.2 --- Un-calibrated 3D reconstruction --- p.14 / Chapter 2.3 --- Self calibrated 3D reconstruction --- p.16 / Chapter 2.4 --- Initial model formation using image based --- p.18 / Chapter 2.5 --- Volumes from Silhouettes --- p.19 / Chapter 3 - --- Initial model reconstruct the problem with mismatch noise --- p.22 / Chapter 3.1 --- Perspective Camera Model --- p.24 / Chapter 3.2 --- "Intrinsic parameters, Extrinsic parameters and camera motion" --- p.25 / Chapter 3.2.1 --- Intrinsic parameters --- p.25 / Chapter 3.2.2 --- Extrinsic parameter and camera motion --- p.27 / Chapter 3.3 --- Lowe's method --- p.29 / Chapter 3.4 --- Interleave bundle adjustment for structure and motion recovery from multiple images --- p.32 / Chapter 3.5 --- Feature points mismatch analysis --- p.38 / Chapter 4 - --- Feature selection by using look forward silhouette clipping --- p.43 / Chapter 4.1 --- Introduction to silhouette clipping --- p.43 / Chapter 4.2 --- Silhouette clipping for 3D model --- p.45 / Chapter 4.3 --- Implementation --- p.52 / Chapter 4.3.1 --- Silhouette extraction program --- p.52 / Chapter 4.3.2 --- Feature filter for alternative bundle adjustment algorithm --- p.59 / Chapter 5 - --- Experimental data --- p.61 / Chapter 5.1 --- Simulation --- p.61 / Chapter 5.1.1 --- Input of simulation --- p.61 / Chapter 5.1.2 --- Output of the simulation --- p.66 / Chapter 5.1.2.1 --- Radius distribution --- p.66 / Chapter 5.1.2.2 --- 3D model output --- p.74 / Chapter 5.1.2.3 --- VRML plotting --- p.80 / Chapter 5.2 --- Real Image testing --- p.82 / Chapter 5.2.1 --- Toy house on a turntable test --- p.82 / Chapter 5.2.2 --- Other tests on turntable --- p.86 / Chapter 6 - --- Conclusion and discussion --- p.89
35

3D coarse-to-fine reconstruction from multiple image sequences.

January 2004 (has links)
Ip Che Yin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 119-127). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.1 / Chapter 1.2 --- Previous Work --- p.2 / Chapter 1.2.1 --- Reconstruction for Architecture Scene --- p.2 / Chapter 1.2.2 --- Super-resolution --- p.4 / Chapter 1.2.3 --- Coarse-to-Fine Approach --- p.4 / Chapter 1.3 --- Proposed solution --- p.6 / Chapter 1.4 --- Contribution --- p.6 / Chapter 1.5 --- Publications --- p.7 / Chapter 1.6 --- Layout of the thesis --- p.7 / Chapter 2 --- Background Techniques --- p.8 / Chapter 2.1 --- Interest Point Detectors --- p.8 / Chapter 2.1.1 --- Scale-space --- p.9 / Chapter 2.1.2 --- Harris Corner detectors --- p.10 / Chapter 2.1.3 --- Other Kinds of Interest Point Detectors --- p.17 / Chapter 2.1.4 --- Summary --- p.18 / Chapter 2.2 --- Steerable filters --- p.19 / Chapter 2.2.1 --- Orientation estimation --- p.20 / Chapter 2.3 --- Point Descriptors --- p.22 / Chapter 2.3.1 --- Image derivatives under illumination change --- p.23 / Chapter 2.3.2 --- Image derivatives under geometric scale change --- p.24 / Chapter 2.3.3 --- An example of a point descriptor --- p.25 / Chapter 2.3.4 --- Other examples --- p.25 / Chapter 2.4 --- Feature Tracking Techniques --- p.26 / Chapter 2.4.1 --- Kanade-Lucas-Tomasi (KLT) Tracker --- p.26 / Chapter 2.4.2 --- Guided Tracking Algorithm --- p.28 / Chapter 2.5 --- RANSAC --- p.29 / Chapter 2.6 --- Structure-from-motion (SFM) Algorithm --- p.31 / Chapter 2.6.1 --- Factorization methods --- p.33 / Chapter 2.6.2 --- Epipolar Geometry --- p.39 / Chapter 2.6.3 --- Bundle Adjustment --- p.47 / Chapter 2.6.4 --- Summary --- p.50 / Chapter 3 --- Hierarchical Registration of 3D Models --- p.52 / Chapter 3.1 --- Overview --- p.53 / Chapter 3.1.1 --- The Arrangement of Image Sequences --- p.53 / Chapter 3.1.2 --- The Framework --- p.54 / Chapter 3.2 3 --- D Model Reconstruction for Each Sequence --- p.57 / Chapter 3.3 --- Multi-scale Image Matching --- p.59 / Chapter 3.3.1 --- Scale-space interest point detection --- p.61 / Chapter 3.3.2 --- Point descriptor --- p.61 / Chapter 3.3.3 --- Point-to-point matching --- p.63 / Chapter 3.3.4 --- Image transformation estimation --- p.64 / Chapter 3.3.5 --- Multi-level image matching --- p.66 / Chapter 3.4 --- Linkage Establishment --- p.68 / Chapter 3.5 --- 3D Model Registration --- p.70 / Chapter 3.6 --- VRML Modelling --- p.73 / Chapter 4 --- Experiment --- p.74 / Chapter 4.1 --- Synthetic Experiments --- p.74 / Chapter 4.1.1 --- Study on Rematching Algorithm --- p.74 / Chapter 4.1.2 --- Comparison between Affine and Metric transforma- tions for 3D Registration --- p.80 / Chapter 4.2 --- Real Scene Experiments --- p.86 / Chapter 5 --- Conclusion --- p.112 / Chapter 5.1 --- Future Work --- p.114 / Chapter A --- Camera Parameters --- p.116 / Chapter A.1 --- Intrinsic Parameters --- p.116 / Chapter A.2 --- Extrinsic Parameters --- p.117 / Bibliography --- p.127
36

Regularized wave equation migration for imaging and data reconstruction

Kaplan, Sam Teich 11 1900 (has links)
The reflection seismic experiment results in a measurement(reflection seismic data) of the seismic wavefield. The linear Born approximation to the seismic wavefield leads to a forward modelling operator that we use to approximate reflection seismic data in terms of a scattering potential. We consider approximations to the scattering potential using two methods: the adjoint of the forward modelling operator (migration), and regularized numerical inversion using the forward and adjoint operators. We implement two parameterizations of the forward modelling and migration operators: source-receiver and shot-profile. For both parameterizations, we find requisite Green's function using the split-step approximation. We first develop the forward modelling operator, and then find the adjoint (migration) operator by recognizing a Fredholm integral equation of the first kind. The resulting numerical system is generally under-determined, requiring prior information to find a solution. In source-receiver migration, the parameterization of the scattering potential is understood using the migration imaging condition, and this encourages us to apply sparse prior models to the scattering potential. To that end, we use both a Cauchy prior and a mixed Cauchy-Gaussian prior, finding better resolved estimates of the scattering potential than are given by the adjoint. In shot-profile migration, the parameterization of the scattering potential has its redundancy in multiple active energy sources (i.e. shots). We find that a smallest model regularized inverse representation of the scattering potential gives a more resolved picture of the earth, as compared to the simpler adjoint representation. The shot-profile parameterization allows us to introduce a joint inversion to further improve the estimate of the scattering potential. Moreover, it allows us to introduce a novel data reconstruction algorithm so that limited data can be interpolated/extrapolated. The linearized operators are expensive, encouraging their parallel implementation. For the source-receiver parameterization of the scattering potential this parallelization is non-trivial. Seismic data is typically corrupted by various types of noise. Sparse coding can be used to suppress noise prior to migration. It is a method that stems from information theory and that we apply to noise suppression in seismic data. / Geophysics
37

Reconstruction of Protein Backbone with the £\-arbon Coordinates

Wang, Jen-hui 28 August 2007 (has links)
Given an amino acid sequence with the £\-carbon 3D coordinates on its backbone, the all-atom protein backbone reconstruction problem (PBRP) is to rebuild the 3D coordinates of all atoms (N, C and O atoms) on the backbone. In this thesis, we propose a method for solving PBRP based on the homology modeling. First, we extract all consecutive 4-residue fragments from all protein structures in PDB. Each fragment is identified by its second, third and fourth residues. Thus, the fragments are classified into 8000 residue groups. In each residue group, the fragments with similar structures are clustered together. And one typical fragment is used to represent one cluster. These typical fragments form our fragment library. Then, we find out possible candidates in the fragment library to reconstruct the backbone of the target protein. To test the performance of our method, we use two testing sets of target proteins, one was proposed by Maupetit et al. [20] and the other is a subset extracted from CASP7. We compare the experimental results of our method with three previous works MaxSprout, Adcock¡¦s method, and SABBAC proposed by Maupetit et al.. The reconstruction accuracy of our method is comparable to these previous works. And the solution of our method is more stable than the previous works in most target proteins. The time efficiency of our method is also satisfactory.
38

The Acropolis at Babylon: A Reconstruction during the Late 6th Century B.C.

Parkoff, Justin 1981- 14 March 2013 (has links)
This thesis reconstructs the royal Acropolis at Babylon and selected adjacent areas as they likely appeared during the late 6th century B.C. Today, all that remains of Babylon is scant archaeological ruins of building foundations. It is difficult to appreciate that the site had been home to even a provincial town, much less one of the most magnificent capital cities the Middle East has ever known. Through the use of archaeological reports and iconography, the author analyzed the architecture to determine the most probable appearance of Babylon’s lost monuments. The product of this research reconstructed the massive palatial complexes and their defensive enclosures in the form of a three-dimensional digitized AutoCAD model. This interpretation postulates the most accurate portrayal of the Babylonian Acropolis during the height of its occupation. By examining the fortifying architecture, this study offers a unique perspective into the defensive nature of the Babylonian mindset and through it shows how Babylon came to be considered one of the marvels of its time.
39

H.M.S. Pallas: historical reconstruction of an 18th-century Royal Navy frigate

Flynn, Peter Erik 16 August 2006 (has links)
A 1998 joint survey undertaken by the Institute of Nautical Archaeology and Portuguese authorities located and identified the sunken remains of the Royal Navy frigate HMS Pallas (1757-1783) off of the Azorean island of São Jorge. Physical remains are so limited as to suggest that excavation would likely yield little new information. However, much documentary evidence has been preserved in Admiralty archives. Contemporary treatises about 18th-century British ship construction focus on glossaries of terms, scantling lists and design theory, and include only short sections on frigates insofar as they apply to those topics. They rarely address specific construction aspects. Most current works address individual aspects of ship construction for the period, but provide little significant detail about the frigate as a ship type. All of these works are useful and reliable, however none attempt to combine the ship with the crew, or pursue the complete history of one ship. As the flagship of a prototypical class, intended to address French superiority in cruiser design, it is reasonable to expect that a history of Pallas would exist with some analysis of how successfully these new frigates fulfilled the Royal Navy’s perceived need. However, to date there has been no attempt to consolidate the evidence of her 26-year career. This study provides a comprehensive history of a single ship from perceived need and conceived solution through design and construction. The ship’s logbooks and additional primary sources made it possible to accurately document and analyze Pallas’ activities, maintenance, modifications, and ultimately to draw conclusions about the overall effectiveness of the frigate type. I began with basic background information to establish the perceived need for a new frigate type, followed by an examination of the conceived design solution. A partial set of admiralty drafts served as a foundation from which to develop a more complete set of construction plans, a spar plan, and rigging plans. Comprehensive research into life aboard Royal Navy warships of the period provided a social context within which to examine the service history of Pallas. Finally, a review of the maintenance record and the events leading up to her sinking enabled an informed assessment of how well HMS Pallas fulfilled the perceived need for which she was developed.
40

Crime and order in San Antonio during the Civil War and Reconstruction

Perrin, Teresa Thomas, January 2001 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI Company.

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