Groupwise non-rigid image registration is a powerful tool to automatically establish correspondences across sets of images. Such correspondences are widely used for constructing statistical models of shape and appearance. As existing techniques usually treat registration as an optimisation problem, a good initialisation is required. Although the standard initialisation---affine transformation---generally works well, it is often inadequate when registering images of complex structures. In this thesis we present a sophisticated system that uses the sparse matches of one or more parts+geometry models as the initialisation. We show that both the model/s and its/their matches can be automatically obtained, and that the matches are able to effectively initialise a groupwise non-rigid registration algorithm, leading to accurate dense correspondences. We also show that the dense mesh models constructed during the groupwise registration process can be used to accurately annotate new images. We demonstrate the efficacy of the proposed system on three datasets of increasing difficulty, and report on a detailed quantitative evaluation of its performance.

Este trabalho descreve a metodologia desenvolvida para fabricação e comissionamento de um novo conceito de máquina para realização de testes de fadiga por ressonância de tubos rígidos em escala real, visando oferecer soluções técnicas para determinados pontos de melhoria encontrados em equipamentos já existentes. O equipamento foi desenvolvido sob os conceitos de análise vibratória, com o auxílio de ferramentas de CAD e método de elementos finitos. A metodologia de projeto do equipamento foi desenvolvida através de projeto conceitual e seleção de conceito, atingindo evolução gradual através de testes experimentais e aplicação contínua de melhorias. Uma vez fabricada a máquina, foi realizado um teste em trecho de duto íntegro, sem costura, com elevado nível de corrosão superficial externa, visando a validação do projeto e o comissionamento da bancada de testes. Este trecho de duto é de aço API 5L X65 com seis metros de comprimento, 219,1 mm de diâmetro externo e 22,2 mm de espessura, com pressão interna de 200 bar, acrescida de deformação com amplitude constante média de ± 750 μm/m no centro do tubo. O critério de falha adotado foi o surgimento de uma trinca na direção circunferencial, passante ao longo da espessura. Durante o teste, foram adquiridos os dados de deformação, aceleração, frequência, pressão interna, temperatura interna e temperatura ambiente. A análise de falha foi realizada na região da fratura para confirmar a ocorrência de fadiga no tubo. O desenvolvimento da bancada e a posterior realização dos ensaios permitiram avaliar a eficiência e a produtividade do equipamento, o qual se mostrou vantajoso frente aos conceitos existentes e apto para a execução de testes em tubos rígidos de forma rápida e satisfatória. / Este trabalho descreve a metodologia desenvolvida para fabricação e comissionamento de um novo conceito de máquina para realização de testes de fadiga por ressonância de tubos rígidos em escala real, visando oferecer soluções técnicas para determinados pontos de melhoria encontrados em equipamentos já existentes. O equipamento foi desenvolvido sob os conceitos de análise vibratória, com o auxílio de ferramentas de CAD e método de elementos finitos. A metodologia de projeto do equipamento foi desenvolvida através de projeto conceitual e seleção de conceito, atingindo evolução gradual através de testes experimentais e aplicação contínua de melhorias. Uma vez fabricada a máquina, foi realizado um teste em trecho de duto íntegro, sem costura, com elevado nível de corrosão superficial externa, visando a validação do projeto e o comissionamento da bancada de testes. Este trecho de duto é de aço API 5L X65 com seis metros de comprimento, 219,1 mm de diâmetro externo e 22,2 mm de espessura, com pressão interna de 200 bar, acrescida de deformação com amplitude constante média de ± 750 μm/m no centro do tubo. O critério de falha adotado foi o surgimento de uma trinca na direção circunferencial, passante ao longo da espessura. Durante o teste, foram adquiridos os dados de deformação, aceleração, frequência, pressão interna, temperatura interna e temperatura ambiente. A análise de falha foi realizada na região da fratura para confirmar a ocorrência de fadiga no tubo. O desenvolvimento da bancada e a posterior realização dos ensaios permitiram avaliar a eficiência e a produtividade do equipamento, o qual se mostrou vantajoso frente aos conceitos existentes e apto para a execução de testes em tubos rígidos de forma rápida e satisfatória.

No description available.

Consider the problem of designing the path of a camera in 3D. As we may identify each camera position with a member of the Euclidean motions, SE(3), the problem may be recast mathematically as constructing interpolating curves on the (non-Euclidean) space SE(3). There exist many ways to formulate this problem, and indeed many solutions. In this thesis we shall examine solutions based on simple geometric constructions, with the goal of discovering well behaved and computable solutions. In affine spaces there exist elegant solutions to the problem of curve design, which are collectively known as the techniques of Computer Aided Geometric Design (CAGD). The approach of this thesis will be the generalization of these methods and an examination of computation on matrix Lie groups. In particular, the Lie groups SO(3) and SE(3) will be examined in some detail.

We develop efficient techniques for the non-rigid registration of medical images by using representations that adapt to the anatomy found in such images. Images of anatomical structures typically have uniform intensity interiors and smooth boundaries. We create methods to represent such regions compactly using tetrahedra. Unlike voxel-based representations, tetrahedra can accurately describe the expected smooth surfaces of medical objects. Furthermore, the interior of such objects can be represented using a small number of tetrahedra. Rather than describing a medical object using tens of thousands of voxels, our representations generally contain only a few thousand elements. Tetrahedra facilitate the creation of efficient non-rigid registration algorithms based on finite element methods (FEM). We create a fast, FEM-based method to non-rigidly register segmented anatomical structures from two subjects. Using our compact tetrahedral representations, this method generally requires less than one minute of processing time on a desktop PC. We also create a novel method for the non-rigid registration of gray scale images. To facilitate a fast method, we create a tetrahedral representation of a displacement field that automatically adapts to both the anatomy in an image and to the displacement field. The resulting algorithm has a computational cost that is dominated by the number of nodes in the mesh (about 10,000), rather than the number of voxels in an image (nearly 10,000,000). For many non-rigid registration problems, we can find a transformation from one image to another in five minutes. This speed is important as it allows use of the algorithm during surgery. We apply our algorithms to find correlations between the shape of anatomical structures and the presence of schizophrenia. We show that a study based on our representations outperforms studies based on other representations. We also use the results of our non-rigid registration algorithm as the basis of a segmentation algorithm. That algorithm also outperforms other methods in our tests, producing smoother segmentations and more accurately reproducing manual segmentations.

This thesis examines the design and implementation of an extensible objectoriented physics engine framework. The design and implementation consolidates concepts from the wide literature in the field and clearly documents the procedures and methods. Two primary dynamic behaviors are explored: rigid body dynamics and articulated dynamics. A generalized collision response model is built for rigid bodies and articulated structures which can be adapted to other types of behaviors. The framework is designed around the use of interfaces for modularity and easy extensibility. It supports both a standalone physics engine and a supplement to a distributed immersive rendering environment. We present our results as a number of scenarios that demonstrate the viability of the framework. These scenarios include rigid bodies and articulated structures in free-fall, collision with dynamic and static bodies, resting contact, and friction. We show that we can effectively combine different dynamics into one cohesive structure. We also explain how we can efficiently extend current behaviors to develop new ones, such as altering rigid bodies to produce different collision responses or flocking behavior. Additionally, we demonstrate these scenarios in both the standalone and the immersive environment.

ABSTRACT A water-soluble rigid-rod polyelectrolyte sPBI-PS(Li+) could be doped with LiI and cast as a freestanding film from aqueous solution showing a room-temperature in-plane DC conductivity (s|| ) of 8.3¢®10-3 S/cm. However, the cast film assumed an anisotropic microstructure due to preferential orientation of the rigid-rod backbone leading to an out-of-the plane DC conductivity (s^) which was three orders smaller than those of the s||, and severely limited its applications as a solid polyelectrolyte for thin-film battery. In addition to synthesizing rigid-rod polyelectrolyte sPBI-PS(Li+) for comparison, this study used 2-sulfo-terephthalic acid and isophthalic acid in ratios of 15¡G1, 25¡G1, or 50¡G1 for copolycondensation reaction making the rigid-rod backbone of sPBI-PS(Li+) become articulated. Further reaction with 1,3-propanesultone pendants, the rigid-rod polyelectrolyte was changed into a new water-soluble articulated rigid-rod polyelectrolyte A-sPBI-PS(Li+). Various analyses were applied to ascertain chemical structure, purities, thermal properties and molecular weight of synthesized monomers and polymers. Freestanding films of sPBI-PS(Li+) and A-sPBI-PS(Li+) were cast from aqueous solutions doped with LiI, LiBF4, or LiCF3SO3 for various concentrations up to 5 wt.%. Thin-film room-temperature s|| of sPBI-PS(Li+) could be 3.15´10-3 S/cm, and of A-sPBI-PS(Li+) could be 2.76´10-3 S/cm. X-ray scattering and electron microscopic results suggested that the sPBI-PS(Li+) cast film was in-plane isotropic but out-of-the plane anisotropic, and the A-sPBI-PS(Li+) cast film was three-dimensionally isotropic.

A water-soluble rigid-rod polyelectrolyte sPBI-PS(Li+) could be doped with LiI and cast as a freestanding film from aqueous solution showing a room-temperature in-plane DC conductivity (

ABSTRACT sPBI is a heterocyclic aromatic polymer assuming a para- catenated backbone yielding a rod-like configuration. Because of its rigidity, this rod-like molecule displays superior mechanical tenacity, thermo-oxidative stability, and solvent resistance. It is also the precursor of rigid-rod solid polyelectrolyte exhibiting high solubility and superior ionic conductivity. Isotropic solution were prepared by dissolving sPBI in distilled methanesulfonic acid containing 0.0, 0.989, 4.76, 9.09, 15.0, 20.0, 23.1 wt. % lithium ion of dopants of LiCF3SO3 or LiN(CF3SO2)2. The room-temperature DC conductivity of sPBI cast film doped with 15.0 wt. % LiN(CF3SO2)2 parallel (

It is known in the literature on Automated Highway Systems that information flow can significantly affect the propagation of errors in spacing in a collection of vehicles. This thesis investigates this issue further for a homogeneous collection of vehicles. Specifically, we consider the effect of information flow on the propagation of errors in spacing and velocity in a collection of vehicles trying to maintain a rigid formation. The motion of each vehicle is modeled using a Linear Time Invariant (LTI) system. We consider undirected and connected information flow graphs, and assume that that each vehicle can communicate with a maximum of q(n) vehicles, where q(n) may vary with the size n of the collection. The feedback controller of each vehicle takes into account the aggregate errors in position and velocity of the vehicles, with which it is in direct communication. The controller is chosen in such a way that the resulting closed loop system is a Type-2 system. This implies that the loop transfer function must have at least two poles at the origin. We then show that if the loop transfer function has three or more poles at the origin, and if the size of the formation is sufficiently large, then the motion of the collection is unstable. Suppose l is the number of poles of the transfer function relating the position of a vehicle with the control input at the origin of the complex plane, and if the number (q(n)l+1)/(nl) -> 0 as n -> (Infinity), then we show that there is a low frequency sinusoidal disturbance with unity maximum amplitude acting on each vehicle such that the maximum errors in spacing response increase at least as much as O (square_root(n^l/(q(n)^(l+1)) ) consequence of the results presented in this paper is that the maximum of the error in spacing and velocity of any vehicle can be made insensitive to the size of the collection only if there is at least one vehicle in the collection that communicates with at least O(square_root(n)) other vehicles in the collection.