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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.
191

An efficient wavelet representation for large medical image stacks

Forsberg, Daniel January 2007 (has links)
Like the rest of the society modern health care has to deal with the ever increasing information flow. Imaging modalities such as CT, MRI, US, SPECT and PET just keep producing more and more data. Especially CT and MRI and their 3D image stacks cause problems in terms of how to effectively handle these data sets. Usually a PACS is used to manage the information flow. Since a PACS often is implemented with a server-client setup, the management of these large data sets requires an efficient representation of medical image stacks that minimizes the amount of data transmitted between server and client and that efficiently supports the workflow of a practitioner. In this thesis an efficient wavelet representation for large medical image stacks is proposed for the use in a PACS. The representation supports features such as lossless viewing, random access, ROI-viewing, scalable resolution, thick slab viewing and progressive transmission. All of these features are believed to be essential to form an efficient tool for navigation and reconstruction of an image stack. The proposed wavelet representation has also been implemented and found to be better in terms of memory allocation and amount of data transmitted between server and client when compared to prior solutions. Performance tests of the implementation has also shown the proposed wavelet representation to have a good computational performance.
192

Evaluación estructural, superficial y funcional del pavimento de la pista principal aeropuerto de Pisco: Renan Elias Olivera

Guzmán García, Dany Julian, Ulloa Clavijo, Javier Francisco January 2015 (has links)
La presente tesis para optar el grado de Ingeniero Civil se titula “Evaluación estructural, superficial y funcional del pavimento de la pista principal aeropuerto de Pisco: Renán Elías Olivera”. El objetivo de la investigación ha sido explicar los elementos de la evaluación estructural, superficial y funcional del pavimento de la pista principal del Aeropuerto de Pisco “Renán Elías Olivera” para cumplir con la Norma establecida por las FAA. La metodología utilizada es de tipo descriptivo – aplicada y de diseño cualitativo – cuantitativo. La hipótesis general ha comprobado lo siguiente: “existe una relación significativa entre los elementos de la evaluación estructural, superficial y funcional del pavimento de la pista principal del Aeropuerto de Pisco “Renán Elías Olivera” y el cumplimiento con la Norma establecida por las FAA para llegar a ser admitido como aeropuerto alterno del Jorge Chávez. La validación de la Hipótesis ha quedado comprobada y demostrada a través del análisis de los diferentes estratos del suelo, espesores característicos del suelo de fundación por medio de calicatas y las características de la pista asfáltica del Aeropuerto Renán Elías Olivera y el cumplimiento de la Norma establecida por la Federal Aviation Administration (FAA), generando la conclusión general, como resultado de la comprobación de la hipótesis global mediante el siguiente enunciado: “…Se ha podido determinar que la evaluación estructural, superficial y funcional del pavimento de la pista principal aeropuerto de Pisco: Renán Elías Olivera cumple con los requerimientos de la FAA para ser un aeropuerto alterno al Jorge Chávez”. This thesis for the degree of Civil Engineer is entitled "Structural evaluation, functional surface and the floor of the main runway airport in Pisco: Renan Elias Olivera". The aim of the research was to explain the elements of structural, surface and functional assessment of the main runway pavement Airport Pisco "Renan Elias Olivera" to meet the standard set by the FAA. The methodology is descriptive - applied design and qualitative - quantitative. The general assumption has proven that: "there is a significant relationship between structural elements, surface and functional assessment of the main runway pavement Airport Pisco" Renan Elias Olivera "and compliance with the standard set by the FAA become accepted as an alternate airport Jorge Chavez. Validation of the hypothesis has been tested and demonstrated through the analysis of different soil layers, soil thickness characteristic foundation through pits and characteristics of the asphalt airport runway Renan Elias Olivera and compliance with the standard set by the Federal Aviation Administration (FAA), generating the overall conclusion as a result of the verification of the overall hypothesis by the following statement: "... It has been determined that the structural, surface and functional evaluation of pavement from the main runway airport Pisco: Renan Elias Olivera meets the requirements of the FAA to be an alternate airport Jorge Chavez".
193

Extraction, caractérisation et mesure de courbes imparfaites en résolution limitée / Extraction, characterization and measurement of imperfect curves in limited resolution

Rahmoun, Somia 04 December 2017 (has links)
Dans le domaine moléculaire, les polymères sont observés et étudiés par microscopie. Les formes obtenues sont souvent imprécises en raison de l'effet de convolution et de diffraction de l'acquisition par microscopie. Par conséquent, le polymère apparait comme une courbe épaisse, bruitée et floue. Pour étudier les caractéristiques d'une chaîne de polymère, une des approches possibles consiste à réduire la forme acquise par microscope à une représentation minimale, soit une courbe. Cette dernière doit représenter au mieux l'objet étudié malgré les différentes difficultés rencontrées telles que la qualité des images ou les imprécisions dues à la discrétisation. De plus, un polymère adopte un mouvement "Reptilien" et peut former des géométries complexes telles que des courbes fermées ou avec boucles. L'objet de cette thèse est donc l'extraction de courbes visant à fournir une représentation minimale des polymères à des fins d'analyse. La méthode que nous proposons comprend deux grandes étapes à savoir : L'extraction des géodésiques et leur fusion. La première étape consiste à calculer un ensemble de géodésiques, chacune parcourant une partie distincte de la forme. Ces morceaux de géodésiques sont fusionnés dans la seconde étape afin de générer la courbe complète. Afin de représenter la reptation, les géodésiques doivent être fusionnées dans un ordre précis. Nous modélisons ce problème par graphes et nous cherchons l'ordre de fusion en parcourant le graphe. La fusion est effectuée selon le chemin optimal minimisant différentes contraintes. / In the molecular field, polymers are observed and studied by microscopy. The shapes obtained are often inaccurate because of the convolution and diffraction effect of microscopy. Therefore, the polymer appears as a thick, noisy and fuzzy curve. In order to study a polymer chain, one of the possible approaches consists in reducing the acquired shape to a minimal representation, ie a curve. This curve must represent the studied object in the best way, despite the various encountered difficulties, such as the quality of the images or inaccuracies due to discretization. In addition, a polymer performs a "Reptilian" movement and can form complex geometries such as closed and looped curves. The object of this thesis is, therefore, the extraction of curves aimed at providing a minimal representation of the polymers for analysis. The proposed method comprises two major steps: geodesics extraction and their fusion. The first step is to compute a set of geodesics, each one traversing a distinct part of the shape. These pieces of geodesics are fused in the second step to generate the complete curve. In order to represent the reptation, the geodesics have to be merged in a precise order. We model this problem by graphs and consider the fusion as a graph traversal problem. The fusion is performed according to the optimal path minimizing various constraints.
194

Étude du disque galactique par marquage chimique de ses populations stellaires / Studying the galactic disc by chemically tagging its stellar populations

Guiglion, Guillaume 10 December 2015 (has links)
L'étude de la composition chimique et de la cinématique des étoiles de la Voie Lactée est essentielle afin de comprendre comment les grandes structures de notre Galaxie se sont formées. Les étoiles de faible masse gardent en mémoire dans leur atmosphère la composition chimique du milieu interstellaire dans lequel elles sont nées, et leur cinématique est essentielle afin de caractériser les différentes populations stellaires. Dans cette thèse, nous étudions le disque galactique, composante majeure de notre Galaxie. Dans le cadre de la mission spatiale Gaia, nous avons développé une procédure automatique de mesure d'abondances chimiques, GAUGUIN, utilisée dans le cadre du Gaia-ESO Survey GES (abondances chimiques d'éléments alpha et du pic du fer pour 10000 étoiles) et du projet AMBRE (abondances de lithium pour 7300 étoiles). GAUGUIN va être intégré au pipeline d'analyse des spectres RVS de Gaia. Nous avons étudié l'évolution des dispersions des vitesses dans le disque galactique en fonction du [Mg/Fe], utilisé comme proxy de l'âge. A partir de 6800 étoiles de GES, nous avons détecté la présence d'étoiles du disque épais cinématiquement froides mais avec des valeurs élevées du rapport [Mg/Fe], donc possiblement âgées. Dans le contexte d'un milieu turbulent, nous discutons la présence de ces étoiles dans le cadre des différents modèles de formation du disque galactique. Nous avons également montré que l'abondance du lithium dans le disque montre une croissance avec la métallicité sur le domaine -1<[M/H]<+0 dex et décroît pour les métallicités super-solaires. Enfin, le disque mince et le disque épais seraient caractérisés par des évolutions chimiques différentes en abondance de lithium. / Studying both the chemical composition and kinematics of Milky Way stars is essential to understand how big structures of our Galaxy are formed. Indeed, low-mass stars retain in their photosphere the chemical composition of the interstellar medium is which they were born. Additionally, the kinematics are essential to characterize stellar populations. In this thesis, we focus on the galactic disc, a major component of the Milky Way. In the context of the Gaia mission, we have developed an automatic procedure GAUGUIN, devoted to deriving chemical abundances. We first applied our method to the Gaia-ESO Survey (GES) data to derive alpha and iron-peak chemical abundances for 10000 stars. We then derived lithium abundances for 7300 stars from the AMBRE project. GAUGUIN is well adapted to massive spectroscopic surveys, both in terms of computation time and accuracy. GAUGUIN will be soon integrated into the RVS DPAC analysis pipeline of the Gaia mission. We studied the velocity dispersions in the galactic disc as a function of the [Mg/Fe] ratio, used as an age proxy. Thanks to 6800 GES stars, we detected thick disc stars with cool kinematics and high [Mg/Fe] ratio, so presumably old. In the generally turbulent context of the primitive galactic disc, this thesis places these results in the framework of the different disc formation and evolution scenarios. We also showed that the lithium abundance in the galactic disc increases as a function of the metallicity in the domain -1<[M/H]+0 dex and decreases at super-solar metallicities. Finally, the thin and the thick discs could be characterized by different lithium abundance evolutions.
195

Turbulence Modelling Of Thick Axisymmetric Wall-Bounded Flows And Axisymmetric Plume

Dewan, Anupam 03 1900 (has links) (PDF)
No description available.
196

Conception d'un dispositif de pesage innovant pour véhicule en mouvement et fabrication de transducteurs en couches épaisses / Designing of an innovative wheigh-in-motion device and manufacturing of thick-film transducers

Coudouel, Denis 24 October 2013 (has links)
Cette thèse de doctorat porte sur l'étude et la réalisation d'une plateforme de pesage dynamique pour véhicule roulant basée sur un concept d'intégration de la charge. Ce concept est mis en œuvre en vue de pouvoir minimiser la taille et l'encombrement de ce type de dispositif tout en effectuant des pesées présentant des caractéristiques métrologiques acceptables. Nous démontrons tout d'abord au travers de la réalisation d'un prototype et de plusieurs campagnes d'essais, la faisabilité de la méthode utilisée. Nous évaluons dans un deuxième temps les performances présentées par le prototype lors du pesage de véhicules légers roulant jusqu'à des vitesses de 35km/h. Une étude est ensuite menée sur les jauges de déformation piézorésistives et les jauges piézoélectriques réalisées en couches épaisses grâce à des techniques de sérigraphie. Nous caractérisons ces transducteurs avec pour objectif leur utilisation dans des dispositifs de pesage en remplacement des jauges de déformation classiques à filaments métalliques. / This PhD thesis is devoted to the study and implementation of a weigh-in-motion platform for vehicle based on a concept of integration of load. This concept is used to minimize the size of this kind of device while performing weighings with acceptable results. First, we show thanks to a protoype and several test campagns, the feasability of the method used. In a second time, we evaluate the performances of the prototype in terms of precision and repeatability with the dynamic weighing of vehicles at speeds up to 35km/h. A study is finally conducted on thick-film piezoresitive strain gauges and piezoelectric gauges manufacturing by a screen-printing process with cermet and polymer pastes. We characterize these tranducers with the goal of used them as an alternative of conventional foil strain gauges.
197

Teplotní stárnutí bezolovnatých nízkoteplotních spojů / Thermal aging of lead-free low-temperature joints

Jansa, Vojtěch January 2018 (has links)
The aim of this masterś thesis is to investigate properties of lead-free low-temperature solders after termal aging. The theoretical part is focused on various types of lead - free solders, pastes used for the manufacture of electrical circuits by thick-film technology and methods of testing the properties of the soldered joints. The practical part deals with the design and production of test substrates for testing the solder joints formed between the SMD component and the ceramic substrate. Two solder bismuth-containing solder was selected for testing, the SAC solder was selected as the reference. After aging with temperature cycling from -30 ° C to 115 ° C, the data obtained by testing the mechanical strength of the solder joint by the shear test is evaluated.
198

Využití uhlíkových nanotrubic pro realizaci elektrod tlustovrstvých senzorů / Carbon nanotubes utilization for fabrication of thick-film sensors electrodes

Polický, Jiří January 2010 (has links)
This work covers an area of heavy metals detection by miniaturized thick film sensors. Working electrode of these sensors was fabricated using thick film paste that was prepared as a nanocomposition of carbon nanotubes powder, suitable vehicle and a thinner. The response of fabricated electrodes to cadmium and lead ions was measured using differential pulse voltammetry in an acetate buffer solution using a three electrode sytem. The results were compared with the carbon electrode made from special commercial thick film polymer paste. Finally the possibility of working electrode surface activation with nitric acid and heavy metals on real biological sample detection is described here.
199

Nekonvenční aplikace hybridních integrovaných obvodů / Non conventional applications of HIC´s

Klíma, Martin January 2011 (has links)
This thesis deals with non-conventional applications in the area of thick film technology, especially with indication of the temperature by thermodynamic sensors. The work summarizes thermodynamic sensors theory and also contains production data of the universal thermodynamic sensor realized on ceramic substrate, including measurement of its parameters and heat radiation.
200

Deformačně napěťová analýza a hodnocení mezních stavů částí tlustostěnného potrubí v oblasti creepu. / Stress - strain analysis and creep assessment of the thick-walled tubular structures.

Zouhar, Michal January 2009 (has links)
This thesis deals with the stress-strain analysis of thick-walled pipe parts. The dimension series (characterized by the D/d ratio) of three components are solved, then a direct tube, a torus with constant wall thickness (arcus) and a torus with variable wall thickness (bend). At first, the internal pressure amount, when a fully plastic state for these components is created, is solved. The amount of the limit pressure is determined analytically, numerically and by appropriate normative relations. The results and stress diagrams of individual solutions are mutually compared. Furthermore, these components are solved in the creep and are exposed to the maximum allowable normative internal pressure for 200,000 hours according to the standard – the operating time of components. The place of the maximum equivalent creep strain and the place of the maximum equivalent stress is examined. In these places the principal stresses are depicted depending on the D/d ratio. The results and stress diagrams of individual dimension series are mutually compared. From the available literary sources the condition of the limit state reach is chosen, according to which the evaluation of the limit state reach for individual components is carried out.

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