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Crack propagation and branching are modeled using nonlocal peridynamic theory. One major advantage of this nonlocal theory based analysis tool is the unifying approach towards material behavior modeling- irrespective of whether the crack is formed in the material or not. No separate damage law is needed for crack initiation and propagation. This theory overcomes the weaknesses of existing continuum mechanics based numerical tools (e.g. FEM, XFEM etc.) for identifying fracture modes and does not require any simplifying assumptions. Cracks grow autonomously and not necessarily along a prescribed path. However, in some special situations such as in case of ductile fracture, the damage evolution and failure depend on parameters characterizing the local stress state instead of peridynamic damage modeling technique developed for brittle fracture. For brittle fracture modeling the bond is simply broken when the failure criterion is satisfied. This simulation helps us to design more reliable modeling tool for crack propagation and branching in both brittle and ductile materials. Peridynamic analysis has been found to be very demanding computationally, particularly for real-world structures (e.g. vehicles, aircrafts, etc.). It also requires a very expensive visualization process. The goal of this paper is to bring awareness to researchers the impact of this cutting-edge simulation tool for a better understanding of the cracked material response. A computer code has been developed to implement the peridynamic theory based modeling tool for two-dimensional analysis. A good agreement between our predictions and previously published results is observed. Some interesting new results that have not been reported earlier by others are also obtained and presented in this paper. The final objective of this investigation is to increase the mechanics knowledge of self-similar and self-affine cracks.

This thesis describes the modeling and manufacture of bimorph mirrors as well as an example of their application. A general review of adaptive optics is provided, paying particular attention to those technologies which would allow adaptive optics to be employed in non-astronomical situations. The first stage of the theoretical analysis of the bimorph mirror involves developing a mechanical model of the laminated structure. This is carried out using standard thin plate laminate theory; this results in expressions for the overall sensitivity of a bimorph mirror. The mechanical model also leads to an equation describing the response of the surface of the mirror to a given applied voltage. An analytical solution is developed, and its implementation described. Using this analytical solution, the performance of a bimorph mirror under various operating conditions is analysed. Particular attention is paid to the case of correcting phase fluctuations that have a Kolmogorov spectrum. The process of manufacturing bimorph mirrors is described in some detail, and results of this procedure are presented. Results from various bimorph mirrors are analysed, and the comparisons with the theory are presented. A possible use of bimorph mirrors in laser scanner systems is described. A simple demonstration system is described, and results from its operation are presented. A detailed design for a laser printer using adaptive optics is presented, along with the associated deformable mirror requirements.

Made available in DSpace on 2014-06-11T19:33:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-01-27Bitstream added on 2014-06-13T19:44:22Z : No. of bitstreams: 1 magnajunior_jp_dr_prud.pdf: 3558640 bytes, checksum: fe0b1f329eb24d9ac82adc5a8e9815c8 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O avanço das técnicas de posicionamento, sobretudo do posicionamento por satélites artificiais, impulsionou os processos de atualização da estrutura geodésica fundamental em diversos países. No Brasil, a mais recente mudança foi a adoção do SIRGAS2000 em fevereiro de 2005, se tornando o terceiro referencial adotado oficialmente pelo Sistema Geodésico Brasileiro. A mudança de referencial faz com que produtos cartográficos possam ter suas coordenadas associadas a diferentes referenciais e/ou realizações. Portanto, tornam-se necessários processos de transformação de coordenadas entre sistemas e/ou realizações, que possam modelar as distorções existentes nas materializações e garantir a integridade dos dados. A evolução das técnicas de posicionamento e a atualização dos sistemas de referência são processos dinâmicos, portanto, os métodos para mudança de coordenadas são uma necessidade atual e constante. Nesta pesquisa é apresentado um método para transformação de coordenadas tridimensionais entre realizações de referenciais geodésicos com modelagem de distorções baseado em Thin-Plate Splines (TPS). Pretende-se explorar a capacidade da técnica TPS em modelar dados provenientes de uma transformação linear, juntamente com distorções de natureza... / The advances in the positioning techniques, especially in the satellite positioning, drove the updating process in the fundamental geodesic network in several countries. In Brazil, the most recent change was the adoption of the SIRGAS2000 in February, 2005, as the third official referential adopted by the Brazilian Geodetic System. The change of reference system let cartographic products with his coordinates associated to different reference systems and/or frames. So, processes of coordinates change between reference systems and/or frames are necessary, which are able to model the distortion in the reference frames and guarantee the data integrity. The evolution of the positioning techniques and the updating of reference frames are dynamic processes, so, the methods of coordinates change are an actual and continuous necessity. In this research a method is presented for transformation of threedimensional coordinates between reference frames with modeling of distortions based on Thin-Plate Splines (TPS). It is explored the capacity of the TPS in modeling data originated from a linear transformation, together... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:22:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-07-29Bitstream added on 2014-06-13T19:27:43Z : No. of bitstreams: 1 anjos_ds_me_prud.pdf: 1639941 bytes, checksum: 0860c4a946325bd5e941068ec7106d5e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A representação do relevo ou terreno é uma componente fundamental no processo cartográfico e dentre essas representações as que têm por objetivo analisar as diferentes curvaturas de uma vertente, ou seja, classificar as vertentes de um determinado terreno em retilíneas, côncavas ou convexas tem apresentado grande aplicabilidade em áreas como a agricultura, a construção civil, o estudo de microbacias entre outros. Assim, o desenvolvimento de algoritmos que classifiquem essas formas do relevo pode contribuir muito para a produção de informações relevantes à tomada de decisões em diversas áreas do conhecimento. Alguns algoritmos com esse intuito foram anteriormente desenvolvidos, porém apresentam claras necessidades de melhoria por classificarem apenas áreas pré-estabelecidas, não podendo ser utilizados para outras regiões. Visando sanar a necessidade de implementações mais completas este trabalho apresenta a metodologia utilizada na elaboração de um algoritmo para classificação de vertentes através de ferramentas matemáticas até então pouco utilizadas nas Ciências Cartográficas: a Thin Plate Spline (TPS) que será utilizada para adensar os dados de vertentes do município de Presidente Prudente, gerando Modelos Numérico de Terreno (MNTs) sob os quais a curvatura é calculada, e a Inferência Fuzzy que é uma ferramenta utilizada para discriminar classes que por diversas razões não possuem limites rígidos entre si, como é o caso das vertentes a serem analisadas, e, portanto, estará integrada a um produto final que será parte do estudo, isto é, um sistema que forneça modelos de classificação das vertentes em: retilíneas, côncavas e convexas e que possa ser comparada ao mapa geomorfólogico existente. / The relief or terrain representation is an essential component in the cartographic process. Representations which aim at classifying relief profiles of a certain terrain as rectilinear, concave and convex have reached great applicability in areas such as agriculture, civil construction, watershed studies, among others. Therefore, algorithms that classify these forms of relief can much contribute to the production of relevant information to the decision make in several areas of knowledge. The simplest algorithm, based on curvature value only is clearly not sufficient, but the literature brings fairly little in relation to a more adequate methodology. Attempting to contribute in the sense to aggregate more information and intelligence into this kind of classification so to achieve a more complete implementation, this work presents a methodology using two mathematical tools of little use so far in the Cartographic Science: 1) Thin Plate Spline (TPS) used to densify the existing data, for the Numerical Terrain Models on which the curvature shall be calculated and, 2) Fuzzy Inference used to discriminate classes that for several reasons do not possesses well defined boundaries, as is the curvature profile case. The validation used known and previously chosen data from Presidente Prudente so that a comparison with existing morphological map was possible.

Orientador: Paulo de Oliveira Camargo / Coorientador: Maurício Galo / Banca: João Carlos Chaves / Banca: Messias Meneguette Júnior / Banca: Sônia Maria Alves Costa / Banca: Silvio Jacks dos Anjos Garnés / Resumo: O avanço das técnicas de posicionamento, sobretudo do posicionamento por satélites artificiais, impulsionou os processos de atualização da estrutura geodésica fundamental em diversos países. No Brasil, a mais recente mudança foi a adoção do SIRGAS2000 em fevereiro de 2005, se tornando o terceiro referencial adotado oficialmente pelo Sistema Geodésico Brasileiro. A mudança de referencial faz com que produtos cartográficos possam ter suas coordenadas associadas a diferentes referenciais e/ou realizações. Portanto, tornam-se necessários processos de transformação de coordenadas entre sistemas e/ou realizações, que possam modelar as distorções existentes nas materializações e garantir a integridade dos dados. A evolução das técnicas de posicionamento e a atualização dos sistemas de referência são processos dinâmicos, portanto, os métodos para mudança de coordenadas são uma necessidade atual e constante. Nesta pesquisa é apresentado um método para transformação de coordenadas tridimensionais entre realizações de referenciais geodésicos com modelagem de distorções baseado em Thin-Plate Splines (TPS). Pretende-se explorar a capacidade da técnica TPS em modelar dados provenientes de uma transformação linear, juntamente com distorções de natureza... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The advances in the positioning techniques, especially in the satellite positioning, drove the updating process in the fundamental geodesic network in several countries. In Brazil, the most recent change was the adoption of the SIRGAS2000 in February, 2005, as the third official referential adopted by the Brazilian Geodetic System. The change of reference system let cartographic products with his coordinates associated to different reference systems and/or frames. So, processes of coordinates change between reference systems and/or frames are necessary, which are able to model the distortion in the reference frames and guarantee the data integrity. The evolution of the positioning techniques and the updating of reference frames are dynamic processes, so, the methods of coordinates change are an actual and continuous necessity. In this research a method is presented for transformation of threedimensional coordinates between reference frames with modeling of distortions based on Thin-Plate Splines (TPS). It is explored the capacity of the TPS in modeling data originated from a linear transformation, together... (Complete abstract click electronic access below) / Doutor

Resumo: A representação do relevo ou terreno é uma componente fundamental no processo cartográfico e dentre essas representações as que têm por objetivo analisar as diferentes curvaturas de uma vertente, ou seja, classificar as vertentes de um determinado terreno em retilíneas, côncavas ou convexas tem apresentado grande aplicabilidade em áreas como a agricultura, a construção civil, o estudo de microbacias entre outros. Assim, o desenvolvimento de algoritmos que classifiquem essas formas do relevo pode contribuir muito para a produção de informações relevantes à tomada de decisões em diversas áreas do conhecimento. Alguns algoritmos com esse intuito foram anteriormente desenvolvidos, porém apresentam claras necessidades de melhoria por classificarem apenas áreas pré-estabelecidas, não podendo ser utilizados para outras regiões. Visando sanar a necessidade de implementações mais completas este trabalho apresenta a metodologia utilizada na elaboração de um algoritmo para classificação de vertentes através de ferramentas matemáticas até então pouco utilizadas nas Ciências Cartográficas: a Thin Plate Spline (TPS) que será utilizada para adensar os dados de vertentes do município de Presidente Prudente, gerando Modelos Numérico de Terreno (MNTs) sob os quais a curvatura é calculada, e a Inferência Fuzzy que é uma ferramenta utilizada para discriminar classes que por diversas razões não possuem limites rígidos entre si, como é o caso das vertentes a serem analisadas, e, portanto, estará integrada a um produto final que será parte do estudo, isto é, um sistema que forneça modelos de classificação das vertentes em: retilíneas, côncavas e convexas e que possa ser comparada ao mapa geomorfólogico existente. / Abstract: The relief or terrain representation is an essential component in the cartographic process. Representations which aim at classifying relief profiles of a certain terrain as rectilinear, concave and convex have reached great applicability in areas such as agriculture, civil construction, watershed studies, among others. Therefore, algorithms that classify these forms of relief can much contribute to the production of relevant information to the decision make in several areas of knowledge. The simplest algorithm, based on curvature value only is clearly not sufficient, but the literature brings fairly little in relation to a more adequate methodology. Attempting to contribute in the sense to aggregate more information and intelligence into this kind of classification so to achieve a more complete implementation, this work presents a methodology using two mathematical tools of little use so far in the Cartographic Science: 1) Thin Plate Spline (TPS) used to densify the existing data, for the Numerical Terrain Models on which the curvature shall be calculated and, 2) Fuzzy Inference used to discriminate classes that for several reasons do not possesses well defined boundaries, as is the curvature profile case. The validation used known and previously chosen data from Presidente Prudente so that a comparison with existing morphological map was possible. / Orientador: Messias Meneguette Júnior / Coorientador: João Osvaldo Rodrigues Nunes / Banca: Nilton Nobuhiro Imai / Banca: Ricardo Luis Barbosa / Mestre

Granular media continue to be among the most manipulated materials found in various industries. Particle interactions in granular flow has fundamental importance in analyzing the performance of a wide range of key engineering applications such as hoppers, tumblers, and mixers etc. In spite of such ubiquitous presence, till date, our understanding of the granular flow is very limited. This restricts our ability to design efficient and optimal granular processing equipment. Additionally, the existing design abilities are also constrained by the number of particles to be analyzed, where, a typical industrial application involves millions of particles. This motivated the current research where investigations on the above limitations are pursued from three different angles: experimental, theoretical, and simulation. More specifically, this work aims to study particle-wall interaction and developing a computationally efficient cellular automata simulation framework for industrial granular applications. Towards this end, the current research is divided into two part: (I) energy dissipation during particle-wall interaction (II) cellular automata modeling. In part I, detailed experiments are performed on various sphere-thin plate combinations to measure the coefficient of restitution (COR) which is a measure of energy dissipation and it is one of the most important input parameters in any granular simulation. Alternatively, the energy dissipation measure also used to evaluate the elastic impact performance of superelastic Nitinol 60 material. Explicit finite element simulations are performed to gain detail understanding of the contact process and underlying parameters such as contact forces, stress-strain fields, and energy dissipation modes. A parametric study reveals a critical value of plate thickness above which the effect of plate thickness on the energy dissipation can be eliminated in the equipment design. It is found that the existing analytical expressions has limited applicability in predicting the above experimental and numerical results. Therefore, a new theoretical model for the coefficient of restitution is proposed which combines the effect of plastic deformation and plate thickness (i.e. flexural vibrations). In part II, in order to advance the existing granular flow modeling capabilities for the industry (dry and slurry flows) a cellular automata (CA) modeling framework is developed which can supplement the physically rigorous but computationally demanding discrete element method (DEM). These include a three-dimensional model which takes into account particle friction and spin during collision processing, which provides the ability to handle flows beyond solely the kinetic regime, and a multiphase framework which combines computational fluid dynamics (CFD) with CA to model multi-million particle count applications such as particle-laden flows and slurry flows.

The performance of thin-plate structural systems is known to be greatly influenced by the effect of buckling and post-buckling behaviour. The main factors, which affect the buckling, and post-bucking characteristics and consequently the ultimate performance of thin plate structural components, are noted to be structural geometry, material properties, loading and boundary conditions and geometric imperfections. Present day knowledge and understanding of the buckling and post-buckling behaviour of thin plate structures is at a fairly sophisticated level due to the intensive research that has been carried out over the years in this field of study. This is particularly true for the case of compressive loading whereby the collapse and unloading failure mechanics of thin plate structures has been well documented for this case. The same is not true for the case of shear loading and although much work has been carried out there is a lack of knowledge and in-depth understanding of shear post-ultimate conditions which essentially defines the initiation and progressive development of the plastic failure mechanisms of thin plate structural system. This thesis makes a contribution to the area of study by taking advantage of the developments in recent years of computational technology and computing power to develop finite element modelling strategies and solution procedures using the commercially available FE package PATRAN/NASTRAN to describe in detail the post-buckled shear failure of thin plate structural systems. The work of this thesis provides an in-depth understanding of the complex post-buckled failure mechanics associated with thin-plate structures subjected to in-plane shear displacement and combined shear and compression loading. Simply supported in-plane normal stress free and straight edge boundaries are employed to examine the shear performance as well as the failure mechanisms of thin and stocky web plates. Finite element modelling strategies are developed, which are able to describe the complete loading history from the onset of initial buckling through the nonlinear elastic post-buckling to initial material yielding and its further propagation throughout the structure leading to the development of an appropriate failure mechanism that causes final plastic collapse and subsequent load drop-off. The post-buckled failure response of the thin plate structures is determined with due consideration being given to the effects of geometric and material nonlinearities. The effect of stiffeners on structural performance is detailed for single and multiple asymmetrical and symmetrically attached stiffeners. The degrading influence on the structural performance of cut-outs as well as the considerable redeeming effect due to reinforcements attached at the cut-out boundaries is highlighted in this thesis. The work of the thesis covers the in-plane shear displacement loading of thin web plates, thin web plates with transverse stiffeners, web plates with cut-outs, web plates with stiffened cut-outs and the interactive shear and compressive loading of transversely stiffened web structures. The in-plane shear displacement loading of these structures using the multipoint constraint loading strategy in the finite element modelling procedures has shown to be highly successful in being able to provide an in-depth understanding of the failure mechanics of these structures to a level not to be found in the existing literature.

Positron emission tomography (PET) is a non-invasive imaging technique which utilizes positron-emitting radiopharmaceuticals (PERs) to characterize biological processes in tissues of interest. A PET scanner is usually composed of multiple scintillation crystal detectors placed in a ring so as to capture coincident photons from a position annihilation. These detectors require a crystal lookup table (CLUT) to map the detector response to the crystal of interaction. These CLUTs must be accurate, lest events get mapped to the wrong crystal of interaction degrading the final image quality. This work describes an automated algorithm, for CLUT generation, focused around Gaussian Mixture Models (GMM) with Thin Plate Splines (TPS). The algorithm was tested with flood image data collected from 16 detectors. The method maintained at least 99.8% accuracy across all tests. This method is considerably faster than manual techniques and can be adapted to different detector configurations. / February 2016