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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.
531

Représentation réduite de la segmentation et du suivi des images cardiaques pour l’analyse longitudinale de groupe / Reduced representation of segmentation and tracking in cardiac images for group-wise longitudinal analysis

Rohé, Marc-Michel 03 July 2017 (has links)
Cette thèse présente des méthodes d’imagerie pour l’analyse du mouvement cardiaque afin de permettre des statistiques groupées, un diagnostic automatique et une étude longitudinale. Ceci est réalisé en combinant des méthodes d’apprentissage et de modélisation statistique. En premier lieu, une méthode automatique de segmentation du myocarde est définie. Pour ce faire, nous développons une méthode de recalage très rapide basée sur des réseaux neuronaux convolutifs qui sont entrainés à apprendre le recalage cardiaque inter-sujet. Ensuite, nous intégrons cette méthode de recalage dans une pipeline de segmentation multi-atlas. Ensuite, nous améliorons des méthodes de suivi du mouvement cardiaque afin de définir des représentations à faible dimension. Deux méthodes différentes sont développées, l’une s’appuyant sur des sous-espaces barycentriques construits sur des frames de référence de la séquence et une autre basée sur une représentation d’ordre réduit du mouvement avec des transformations polyaffine. Enfin, nous appliquons la représentation précédemment définie au problème du diagnostic et de l’analyse longitudinale. Nous montrons que ces représentations en- codent des caractéristiques pertinentes permettant le diagnostic des patients atteint d’infarct et de Tétralogie de Fallot ainsi que l’analyse de l’évolution dans le temps du mouvement cardiaque des patients atteints de cardiomyopathies ou d’obésité. Ces trois axes forment un cadre pour l’étude du mouvement cardiaque de bout en bout de l’acquisition des images médicales jusqu’à leur analyse automatique afin d’améliorer la prise de décision clinique grâce à un traitement personnalisé assisté par ordinateur. / This thesis presents image-based methods for the analysis of cardiac motion to enable group-wise statistics, automatic diagnosis and longitudinal study. This is achieved by combining advanced medical image processing with machine learning methods and statistical modelling. The first axis of this work is to define an automatic method for the segmentation of the myocardium. We develop a very-fast registration method based on convolutional neural networks that is trained to learn inter-subject heart registration. Then, we embed this registration method into a multi-atlas segmentation pipeline. The second axis of this work is focused on the improvement of cardiac motion tracking methods in order to define relevant low-dimensional representations. Two different methods are developed, one relying on Barycentric Subspaces built on ref- erences frames of the sequence, and another based on a reduced order representation of the motion from polyaffine transformations. Finally, in the last axis, we apply the previously defined representation to the problem of diagnosis and longitudinal analysis. We show that these representations encode relevant features allowing the diagnosis of infarcted patients and Tetralogy of Fallot versus controls and the analysis of the evolution through time of the cardiac motion of patients with either cardiomyopathies or obesity. These three axes form an end to end framework for the study of cardiac motion starting from the acquisition of the medical images to their automatic analysis. Such a framework could be used for diagonis and therapy planning in order to improve the clinical decision making with a more personalised computer-aided medicine.
532

Wirkpaarungssimulation am Beispiel des innermaschinellen Transports von Stückgütern

Troll, Clemens 13 October 2016 (has links)
Gegenstand dieser Arbeit ist die Simulation einer Wirkpaarung am Beispiel des innermaschinellen Transports von Stückgütern. Zur Schonung des Verarbeitungsgutes wird für das intermittierende Fördern ein neuartiger Bewegungsansatz betrachtet. Da sich der mit diesem Ansatz durchgeführte Prozess sehr sensitiv gegenüber den Eingangsparametern verhält, ist es notwendig, diesen zu simulieren, um somit eine stabile und robuste Bewegung zu synthetisieren. Als grundlegender Modellansatz wird die Diskrete Elemente Methode (DEM) gewählt, da diese es ermöglicht, den Kontakt von Starrkörpern realistisch abzubilden. Zur Umsetzung der Simulation wird die Modellbildung mit zwei unterschiedlichen Modellierungsumgebungen realisiert, die sich hinsichtlich der Umsetzung der DEM unterscheiden: Zum Einen mit Hilfe der kommerziellen Software MATLAB/Simulink und zum Anderen mit Hilfe der Open-Source-Software Woo DEM. Im Anschluss werden die damit erzeugten Modelle verifiziert und experimentell validiert, wodurch sich sowohl die Modellgüte als auch die Modelleignung ableitet. Dabei wird besonders auf die prozessentscheidende Rolle der Reibung eingegangen. Abschließend wird mit Hilfe des Vorzugsmodells an Hand zweier Beispiele die Modellanalyse vollzogen. Hierbei wird der neuartige Bewegungsansatz synthetisiert und simulativ hinsichtlich des Prozesserfolges überprüft. Dabei wird insbesondere auf die mit Hilfe des Modells quanitifizierbaren Prozessgrößen eingegangen. / The subject of this thesis deals with the simulation of an active unit demonstrated by the mechanical transport of pieced goods. To protect the processing goods, a novel motion approach for the intermittent transport is researched. Since the process performed with this approach is very sensitive to its input parameters, it is necessary to simulate it, with the aim to synthesize a stable and robust motion. The Discrete Element Method (DEM) is chosen as the basic model approach, because it allows the realistic representation of rigid body contacts. To implement the simulation the modelling is realised with two different modelling environments, which differ in the implementation of the DEM: Firstly, using the commercial software MATLAB/Simulink and secondly with the help of the open-source-software Woo DEM. Following that the generated models are verified and experimentally validated, whereby both the model goodness and the model suitability are derived. Special attention is dedicated to the role of the process relevant friction. Eventually, the model analysis is carried out with the help of two examples using the preferred model. Here, the novel motion approach is synthesized and verified by simulation in terms of process success. In particular it will address process variables, which are quantifiable because of the model.
533

Análisis del comportamiento de los suelos blandos aplicando la técnica de inclusiones rígidas por los métodos numérico y analítico

Nieto Flores, Jersson Joel, Tolentino Camarena, Miguel Angel 12 January 2021 (has links)
Los suelos blandos originan diversos problemas en el momento de las construcciones, como en las cimentaciones de distintas edificaciones u otras obras civiles. Estos tipos de suelos necesariamente tienen que ser analizados y tratados correctamente, pues, estos originan problemas a corto y largo plazo. En las décadas posteriores se han desarrollado métodos para mejorar el terreno, uno de estos métodos consiste en la construcción, sobre el suelo blando, de elementos verticales rígidos que se llaman inclusiones rígidas. Cuyo principal meta, es la mejora sobre el suelo blando, bajo bases o cimentaciones de estructuras y malos rellenos, permitiendo el desarrollo de las edificaciones con mayor velocidad y disminuyendo los asentamientos de forma sustancial. Al aplicarse esta técnica sobre el terreno blando, se disminuye el asentamiento vertical, ya que al colocarse una capa de reparto que distribuye toda la carga de la estructura se transfiere todo el peso a las inclusiones, minimizando la carga sobre el terreno blando y por consecuente el asentamiento. Como parte de esta tesis presentaremos dos métodos para estudiar el asentamiento de edificaciones que descansan sobre un suelo blando mejorado con la técnica de inclusiones rígidas. El desarrollo de la solución es completamente analítico, pero los análisis de elementos finitos se utilizan para verificar la validez de algunas suposiciones, como un modelo geométrico simplificado, la distribución de la carga con la profundidad y las condiciones de contorno. El perfil del suelo se divide en secciones horizontales independientes, y el equilibrio de las tensiones y la compatibilidad de las deformaciones se presentan en las direcciones vertical y horizontal. La solución se presenta desarrollando un análisis numérico (Plaxis) comparándolo con el método analítico (Combarte) y se puede implementar fácilmente en una hoja de cálculo. / The soft soils cause various problems at the time of construction, as in the foundations of different buildings or other civil works. These types of soils necessarily have to be analyzed and treated correctly, as these cause short and long term problems. In the last decades methods have been developed for the improvement of the land, one of these methods consists of the introduction or construction in the soft soil of rigid vertical elements that are called inclusions. Its main application is in soils under large landfills or foundations of structures, allowing the construction of buildings with greater speed and decreasing settlements considerably. By applying this technique on the soft ground, vertical settlement is reduced, since by placing a distribution layer that distributes the entire load of the structure, all the weight is transferred to the inclusions, minimizing the load on the soft ground and consequently settlement. As part of this thesis we will present two methods to study the settlement of buildings that rest on a soft soil improved with the technique of rigid inclusions. The development of the solution is completely analytical, but the finite element analyzes are used to verify the validity of some assumptions, such as a simplified geometric model, the distribution of the load with the depth and the boundary conditions. The floor profile is divided into independent horizontal sections, and the balance of the stresses and the compatibility of the deformations are presented in the vertical and horizontal directions. The solution is presented by developing a numerical analysis (Plaxis) comparing it with the analytical method (Combarieu) and can be easily implemented in a spreadsheet. / Tesis
534

Visual Appearances of the Metric Shapes of Three-Dimensional Objects: Variation and Constancy

Yu, Ying January 2020 (has links)
No description available.
535

Elaboración de una base de datos aplicando la técnica del método PCI con un sistema georeferenciado para conocer el estado actual de los pavimentos del distrito de Bellavista-Sullana / Elaboration of a database applying the technique of the PCI Method with a georeferenced system to know the current state of the rigid and flexible pavements of the district of Bellavista, Sullana

Nole Dávila, Kelly Margot, Sotomayor Solano, Yordan Luis 06 April 2021 (has links)
La presente tesis tiene por finalidad elaborar una base de datos en el Software Qgis, aplicando la técnica del Método PCI con un sistema georreferenciado para conocer el estado actual de los pavimentos rígidos y flexibles del distrito de Bellavista, Sullana. En primer lugar, se zonifica el área de análisis según el tipo de pavimento que presentan las vías y se realiza la clasificación de las calles y transversales donde es aplicable el Método PCI (Pavement condition Index). Seguido de la obtención de las cantidades de unidades de muestra por secciones (avenidas, calles o transversales), para posteriormente realizar el inventario de fallas en una hoja de registro y obtener el índice de condición de las unidades de muestra, y más adelante determinar la condición de toda la calle. Con la información recolectada en campo, y después de haber realizado el levantamiento topográfico de las secciones analizadas que es determinante para elaborar la base de datos en el software, se lleva a cabo el seguimiento a las fallas para determinar sus coordenadas UTM utilizando un GPS navegador. Una vez obtenida el detalle de las fallas y sus respectivas coordenadas se procede a realizar los trabajos de gabinete donde se modela en el Software Qgis el mapa catastro y se insertan las coordenadas de cada falla evaluada. Por lo que, el estudio se centra en crear una base de datos con los índices de condición de las vías que componen el distrito de Bellavista. Finalmente, a través de la base de datos se puede generar una herramienta útil y eficaz para la Municipalidad de Bellavista, ya que actualmente no cuenta con información suficiente para realizar el control y monitoreo de los pavimentos. / The purpose of this thesis is to elaborate a database in the Qgis Software, applying the PCI Method technique with a georeferenced system to know the current state of rigid and flexible pavements in the Bellavista district, Sullana. In the first place, the analysis area is zoned according to the type of pavement that the roads present and the classification of the streets and cross-sections where the PCI Method (Pavement condition Index) is applicable is carried out. Followed by obtaining the quantities of sample units by sections (avenues, streets or cross-sections), to later carry out the inventory of failures in a record sheet and obtain the condition index of the sample units, and later determine the condition of the entire street. With the information collected in the field, and after having carried out the topographic survey of the analyzed sections, which is decisive for preparing the database in the software, the faults are tracked to determine their UTM coordinates using a GPS navigator. . Once the details of the faults and their respective coordinates have been obtained, the cabinet work is carried out where the cadastre map is modeled in the Qgis Software and the coordinates of each evaluated fault are inserted. Therefore, the study focuses on creating a database with the condition indices of the roads that make up the Bellavista district. Finally, through the database, a useful and effective tool can be generated for the Municipality of Bellavista, since it currently does not have enough information to carry out the control and monitoring of the pavements. / Tesis
536

Compliant robotic arms for inherently safe physical human-robot interaction

She, Yu January 2018 (has links)
No description available.
537

Optimizing Slab Thickness and Joint Spacing for Long-Life Concrete Pavement in Ohio

ALJhayyish, Anwer K. 04 June 2019 (has links)
No description available.
538

Dynamic Amplification Factor Proposal for Seismic Resistant Design of Tall Buildings with Rigid Core Structural System

Quezada, Eder, Serrano, Yaneth, Huaco, Guillermo 01 January 2021 (has links)
El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Currently, there is an increase in the demand for tall buildings in the city of Lima. This research proposes to reduce the dynamic amplification factor through the seismic design of tall buildings based on the requirements of Peruvian code considering that they are regular in plan and height. Minimum base shear values according to the comparison of static seismic shear and dynamic shear from the spectral modal analysis were reviewed for cases of buildings larger than 120 m. The study of 28 reinforced concrete buildings was proposed, with different heights - varying from 24 to 36 floors, with different floor configurations, as well as the arrangement of the walls considering as a rigid core structural system. Additionally, the characteristics of the materials, the loads and combinations were defined. The responses of these buildings were determined by the response spectrum analysis (RSA) and then compared with those obtained by the lineal response history analysis (LRHA), for the last analysis, five Peruvian seismic records were used and scaled to 0.45 g. The seismic responses of the LRHA procedure were taken as a benchmark. The result of this study is the analysis and proposal of the C/R factor for high-rise buildings, as well as obtaining the base shear and drift verification. Minimum base shear values can be reduced for high or long-term buildings, being regular in plan and height. / Revisión por pares
539

Assessment of Reduced Fidelity Modeling of a Maneuvering Hypersonic Vehicle

Dreyer, Emily Rose 29 September 2021 (has links)
No description available.
540

The Pseudo-Rigid-Body Model for Dynamic Predictions of Macro and Micro Compliant Mechanisms

Lyon, Scott Marvin 15 April 2003 (has links) (PDF)
This work discusses the dynamic predictions of compliant mechanisms using the Pseudo-Rigid-Body model (PRBM). In order to improve the number of mechanisms that can be modeled, this research develops and identifies several key concepts in the behavior of beam segments where both ends are fixed to a rigid body (fixed-fixed flexible segments). A model is presented, and several examples are discussed. The dynamic behavior of several compliant segments is predicted using the PRBM and the results are compared to finite element analysis and experimental results. Details are presented as to the transient behavior of a typical uniform rectangular cross section beam. The results of this study are extended and applied to compliant planar mechanisms. It is shown by comparison with finite element analysis and experimental results that the PRBM is a good model of the physical system's dynamic behavior. The method is also demonstrated for use with compliant microelectromechanical (MEMS) systems.

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