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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.
91

Strategy for construction of polymerized volume data sets

Aragonda, Prathyusha 12 April 2006 (has links)
This thesis develops a strategy for polymerized volume data set construction. Given a volume data set defined over a regular three-dimensional grid, a polymerized volume data set (PVDS) can be defined as follows: edges between adjacent vertices of the grid are labeled 1 (active) or 0 (inactive) to indicate the likelihood that an edge is contained in (or spans the boundary of) a common underlying object, adding information not in the original volume data set. This edge labeling “polymerizes” adjacent voxels (those sharing a common active edge) into connected components, facilitating segmentation of embedded objects in the volume data set. Polymerization of the volume data set also aids real-time data compression, geometric modeling of the embedded objects, and their visualization. To construct a polymerized volume data set, an adjacency class within the grid system is selected. Edges belonging to this adjacency class are labeled as interior, exterior, or boundary edges using discriminant functions whose functional forms are derived for three local adjacency classes. The discriminant function parameter values are determined by supervised learning. Training sets are derived from an initial segmentation on a homogeneous sample of the volume data set, using an existing segmentation method. The strategy of constructing polymerized volume data sets is initially tested on synthetic data sets which resemble neuronal volume data obtained by three-dimensional microscopy. The strategy is then illustrated on volume data sets of mouse brain microstructure at a neuronal level of detail. Visualization and validation of the resulting PVDS is shown in both cases. Finally the procedures of polymerized volume data set construction are generalized to apply to any Bravais lattice over the regular 3D orthogonal grid. Further development of this latter topic is left to future work.
92

Control of Double Inverted Pendulum First Approach

DABRETAU, Teerapong, DAREINI, Ali January 2015 (has links)
An Inverted double pendulum is a combination of two individual pendulums which represents an example of a nonlinear and unstable dynamic system and it is also a good example of a physical system which can exhibit chaotic behavior.This document contains a first analysis of the model and the control of this system. Also presented is the installation of the electrical materials needed to control the system contain instrumenting the motor, current measurement system, motor shaft angle sensor, vision systemand MYRIO which is an embedded hardware device created by National Instruments will be used for data acquisition and control the system
93

PERFORMANCE ANALYSIS OF SRCP IMAGE BASED SOUND SOURCE DETECTION ALGORITHMS

Nalavolu, Praveen Reddy 01 January 2010 (has links)
Steered Response Power based algorithms are widely used for finding sound source location using microphone array systems. SRCP-PHAT is one such algorithm that has a robust performance under noisy and reverberant conditions. The algorithm creates a likelihood function over the field of view. This thesis employs image processing methods on SRCP-PHAT images, to exploit the difference in power levels and pixel patterns to discriminate between sound source and background pixels. Hough Transform based ellipse detection is used to identify the sound source locations by finding the centers of elliptical edge pixel regions typical of source patterns. Monte Carlo simulations of an eight microphone perimeter array with single and multiple sound sources are used to simulate the test environment and area under receiver operating characteristic (ROCA) curve is used to analyze the algorithm performance. Performance was compared to a simpler algorithm involving Canny edge detection and image averaging and an algorithms based simply on the magnitude of local maxima in the SRCP image. Analysis shows that Canny edge detection based method performed better in the presence of coherent noise sources.
94

Multiscale methods in signal processing for adaptive optics

Maji, Suman Kumar 14 November 2013 (has links) (PDF)
In this thesis, we introduce a new approach to wavefront phase reconstruction in Adaptive Optics (AO) from the low-resolution gradient measurements provided by a wavefront sensor, using a non-linear approach derived from the Microcanonical Multiscale Formalism (MMF). MMF comes from established concepts in statistical physics, it is naturally suited to the study of multiscale properties of complex natural signals, mainly due to the precise numerical estimate of geometrically localized critical exponents, called the singularity exponents. These exponents quantify the degree of predictability, locally, at each point of the signal domain, and they provide information on the dynamics of the associated system. We show that multiresolution analysis carried out on the singularity exponents of a high-resolution turbulent phase (obtained by model or from data) allows a propagation along the scales of the gradients in low-resolution (obtained from the wavefront sensor), to a higher resolution. We compare our results with those obtained by linear approaches, which allows us to offer an innovative approach to wavefront phase reconstruction in Adaptive Optics.
95

Morphological and statistical techniques for the analysis of 3D images

Meinhardt Llopis, Enric 03 March 2011 (has links)
Aquesta tesi proposa una estructura de dades per emmagatzemar imatges tridimensionals. L'estructura da dades té forma d'arbre i codifica les components connexes dels conjunts de nivell de la imatge. Aquesta estructura és la eina bàsica per moltes aplicacions proposades: operadors morfològics tridimensionals, visualització d'imatges mèdiques, anàlisi d'histogrames de color, seguiment d'objectes en vídeo i detecció de vores. Motivada pel problema de la completació de vores, la tesi conté un estudi de com l'eliminació de soroll mitjançant variació total anisòtropa es pot fer servir per calcular conjunts de Cheeger en mètriques anisòtropes. Aquests conjunts de Cheeger anisòtrops es poden utilitzar per trobar òptims globals d'alguns funcionals per completar vores. També estan relacionats amb certs invariants afins que s'utilitzen en reconeixement d'objectes, i en la tesi s'explicita aquesta relació. / This thesis proposes a tree data structure to encode the connected components of level sets of 3D images. This data structure is applied as a main tool in several proposed applications: 3D morphological operators, medical image visualization, analysis of color histograms, object tracking in videos and edge detection. Motivated by the problem of edge linking, the thesis contains also an study of anisotropic total variation denoising as a tool for computing anisotropic Cheeger sets. These anisotropic Cheeger sets can be used to find global optima of a class of edge linking functionals. They are also related to some affine invariant descriptors which are used in object recognition, and this relationship is laid out explicitly.
96

Nova abordagem para o processamento e análise de imagens topográficas da córnea humana / Nova Abordagem para o Processamento e Análise de Imagens Topográficas da Córnea Humana.

Guilherme Vaz Torres 12 May 2006 (has links)
O presente trabalho trata-se do desenvolvimento de um programa para de análise de imagens de topografia corneana de sistemas comerciais, para ser implementado no topógrafo corneano para Lâmpada de Fenda, em desenvolvimento no Laboratório de Instrumentação Oftálmica - EESC/USP e no Laboratório de Física Oftálmica - FMRP/USP. O programa foi desenvolvido em C++, utilizando a plataforma Windows, e fornece mapas axiais de topografia corneana. O programa foi testado em esferas de calibração e em olhos humanos, apresentando um fator de correlação de 0,9998 para as medidas em esferas e um erro inerente estimado em 3%. Os mapas de topografias axiais em olhos humanos foram comparados com os mapas gerados por sistemas comerciais e o padrão visual de forma e relevo estão em concordância. / This work is about a software for the analisys of corneal topography images provided by commercial available systems to be implemented in a corneal topographer for slit lamps under evelopment at Laboratório de Instrumentação Oftálmica . EESC/USP e no Laboratório de Física Oftálmica . FRMP/USP. The software was developed in Borland C++ Builder for Windows and provides the corneal topography axial maps. The software has been tested in calibration spheres and in human eyes, presenting a correlation factor of 0,9998 for the measurements performed in the spheres and an inherent error of 3%. The axial topographic maps form the exams performe in human eyes have been compared to the axial maps provided by the commercial available system and the visual pattern as well as the relief are in accordance.
97

Um novo algoritmo de granulometria com aplicação em caracterização de nanoestruturas de silício. / A new correlation-based granulometry algorithm with application in characterizing porous silicon nanomaterials.

Ricardo Hitoshi Maruta 14 October 2011 (has links)
Granulometria é o processo usado para medir objetos de diferentes tamanhos em imagens de material granular. Frequentemente algoritmos baseados em morfologia matemática ou detecção de arestas são utilizados para esta finalidade. Propomos uma nova abordagem para a granulometria utilizando correlações cruzadas com círculos de tamanhos diferentes. Esta técnica é primeiramente adequada para a detecção de objetos de formato circular, mas pode ser estendido para outras formas utilizando outros núcleos (kernels) de correlação. Experimentos mostram que o novo algoritmo é robusto ao ruído e pode detectar objetos com pouco contraste e/ou com sobreposição parcial. Este trabalho também apresenta características quantitativas estruturais da camada de silício poroso, obtidas aplicando o algoritmo proposto em imagens de microscopia eletrônica de varredura (MEV). O novo algoritmo, que chamamos Granul, calcula as áreas e frequências dos poros. Processamentos adicionais utilizando outros algoritmos classificam os poros em circulares ou quadrados. Relacionamos os resultados quantitativos obtidos com o processo de fabricação e discutimos o mecanismo de formação do poro quadrado no silício. O novo algoritmo mostrou-se confiável no processamento de imagens de MEV e é uma ferramenta promissora para controle no processo de formação dos poros. / Granulometry is the process of measuring the size distribution of objects in an image of granular material. Usually, algorithms based on mathematical morphology or edge detection are used for this task. We propose a entirely new approach for the granulometry using the cross correlations with circles of different sizes. This technique is primarily adequate for detecting circular shaped objects, but it can be extended to other shapes using other correlation kernels. Experiments show that the new algorithm is greatly robust to noise and can detect even faint objects and/or objects with partial superposition. This paper also reports the quantitative structural characteristics of the porous silicon layer based on the proposed algorithm applied to Scanning Electron Microscopy (SEM) images. The new algorithm, that we call Granul, computes the size distribution of pores and classifies the pores in circular or square ones. We relate these quantitative results to the fabrication process and discuss the square porous silicon formation mechanism. The new algorithm shows to be reliable in SEM images processing and is a promising tool to control the pores formation process.
98

Caractérisation et prédiction probabiliste des variations brusques et importantes de la production éolienne / Characterization and probabilistic forecasting of wind power production ramps

Bossavy, Arthur 06 December 2012 (has links)
L'énergie éolienne est aujourd'hui la source d'énergie renouvelable en plus forte expansion. Le caractère variable et partiellement contrôlable de sa production complexifie la gestion du système électrique. L'utilisation dans divers processus de décision, de prédictions du niveau de production à des horizons de 2-3 jours, permet une meilleure intégration de cette ressource. Certaines situations donnent néanmoins lieu à des performances de prédiction insatisfaisantes. Des erreurs dans la prédiction de l'instant d'apparition de variations brusques et importantes de la production, peuvent être responsables d'importants déséquilibres énergétiques, et avoir un impact négatif sur la gestion du système électrique. L'objectif de cette thèse est de proposer des approches permettant d'une part de caractériser ces variations, et d'autre part de prédire et d'estimer l'incertitude dans l'instant de leur apparition. Dans un premier temps, nous étudions différentes formes de caractérisation de ces variations. Nous proposons un modèle de rupture permettant de représenter le caractère aléatoire dans la proximité des ruptures d'un signal, tout en tenant compte des aspects borné et non-stationnaire du processus de production. A partir de simulations issues de ce modèle, nous réalisons une étude paramétrique destinée à évaluer et comparer les performances de différents filtres et approches multi-échelles de détection. Dans un deuxième temps, nous proposons une approche de prédiction probabiliste de l'instant d'apparition d'une rupture, reposant sur l'utilisation de prévisions météorologiques ensemblistes. Leur conversion en puissance fournit différents scénarii de la production, à partir desquels sont agrégées les prédictions de l'instant d'apparition d'une rupture. L'incertitude associée est représentée à l'aide d'intervalles de confiance temporels et de probabilités estimées conditionnellement. Nous évaluons la fiabilité et la finesse de ces estimations sur la base de mesures de production provenant de différentes fermes éoliennes. / Today, wind energy is the fastest growing renewable energy source. The variable and partially controllable nature of wind power production causes difficulties in the management of power systems. Forecasts of wind power production 2-3 days ahead can facilitate its integration. Though, particular situations result in unsatisfactory prediction accuracy. Errors in forecasting the timing of large and sharp variations of wind power can result in large energy imbalances, with a negative impact on the management of a power system. The objective of this thesis is to propose approaches to characterize such variations, to forecast their timing, and to estimate the associated uncertainty. First, we study different alternatives in the characterization of wind power variations. We propose an edge model to represent the random nature of edge occurrence, along with representing appropriately the bounded and non-stationary aspects of the wind power production process. From simulations, we make a parametric study to evaluate and compare the performances of different filters and multi-scale edge detection approaches. Then, we propose a probabilistic forecasting approach of edge occurrence and timing, based on numerical weather prediction ensembles. Their conversion into power provides an ensemble of wind power scenarios from which the different forecast timings of an edge are combined. The associated uncertainty is represented through temporal confidence intervals with conditionally estimated probabilities of occurrence. We evaluate the reliability and resolution of those estimations based on power measurements from various real world case studies.
99

Automatická optická inspekce / Automatic Optical Inspection

Vápeník, Radovan January 2009 (has links)
This work deals with the technical possibilities for automated optical inspection and the arrangements for monitoring the implementation of established elements. There are used methods of detection elements, including advanced algorithm processing. With the described methods was created program and each method was tested. The aim was on the clear description of the problem, the optimal design and processing program with objective results with the lowest number of false detection.
100

Detekce charakteristických bodů obličeje v telerentgenovén snímku / Detection of characteristic facial features in tele-X-ray image

Hruška, Martin January 2011 (has links)
Description cephalometric images and the characteristic points on the skull for cephalometric analysis. Theoretical analysis of digital image editing and image before the actual detection. The range of possible methods for determining the characteristic points on the face. Experimental verification of edge detectors, Hu moments with neural networks and Haar wavelets with Viola-Jones detector.

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