A nova is a cataclysmic variable star consisting of a white dwarf and a main sequence, subgiant or red giant companion. In a nova explosion, the white dwarf undergoes a thermonuclear runaway on its surface, as a result of build-up of accreted material from its companion. This leads to a large expulsion of matter from the WD surface, as well as a dramatic increase in the optical magnitude of the system. In this thesis, 5GHz C-band e-MERLIN observations of two novae (V959 Mon and V339 Del) and one symbiotic star (AG Pegasi) are presented. V959 Mon is a classical nova which was discovered in June 2012 by the Fermi Large Area Telescope as a gamma-ray source. High resolution e-MERLIN images of V959 Mon were made at six epochs following the June 2012 outburst, between 90 and 615 days after the Fermi discovery. The first four e-MERLIN observations revealed a morphology which was aspherical and expanding in the east-west direction. However, in the last two epochs, V959 Mon's ejecta morphology changed from being elongated east-west to being elongated north-south. Constant velocity models fit to measurements of V959 Mon's angular size at each epoch indicated that the expansion rate of the north-south component was significantly slower than that of the east-west component. The e-MERLIN observations of V339 Del and AG Pegasi were not as well resolved as the observations of V959 Mon, and only limited analysis of their ejecta structure was possible. In order to understand the complicated morphology seen in the e-MERLIN observations of V959 Mon, radio emission models of nova ejecta were constructed, and e-MERLIN observations of them were simulated. When constructing the models, two possible explanations for V959 Mon's morphology were explored. Firstly, the possibility was considered that the elongation observed in V959 Mon's ejecta, which changed over time from east- west to north-south, was spurious, resulting from incomplete sampling of the uv plane by e-MERLIN. To investigate this, an expanding spherical shell of ejecta was simulated, the extent to which its shape was distorted in simulated e-MERLIN images of it was investigated. Secondly, emission from an ejecta model featuring two components - one fast-moving component in the east-west direction, and another, more slow-moving component in the north-south direction - was simulated, in order to determine whether such an ejecta structure could result in the morphology seen in the e-MERLIN observations of V959 Mon. It was found that the spherical, Hubble flow model simulations were a reasonably good fit to V959 Mon's light curve, but could not explain the east-west elongation seen in V959 Mon's ejecta at the early epochs. Simulated observations of the two-component model were morphologically similar to V959 Mon, but produced light curves which were much fainter than V959 Mon's, indicating that a more in-depth analysis of two-component models of nova ejecta is necessary.

Two different aluminium alloys, AA6111 (Al-Mg-Si) and AA7055 (Al-Mg-Zn), were chosen as the aluminium alloys to be welded with DC04, and two welding methods (USW and FSSW) were selected to prepare the welds. Selected pre-welded joints were then annealed at T=400 - 570oC for different times. Kinetics growth data was collected from the microstructure results, and the growth behaviour of the IMC layer was found to fit the parabolic growth law. A grain growth model was built to predict the grain size as a function of annealing time. A double-IMC phase diffusion model was applied, together with grain growth model, to predict the thickness of each phase as a function of annealing time in the diffusion process during heat treatment. In both material combinations and with both welding processes a similar sequence of IMC phase formation was observed during the solid state welding. η-Fe2Al5 was found to be the first IMC phase to nucleate. The IMC islands then spread to form a continuous layer in both material combinations. With longer welding times a second IMC phase, θ-FeAl3, was seen to develop on the aluminium side of the joints. Higher fracture energy was received in the DC04-AA6111 joints than in the DC04-AA7055 joints. Two reasons were claimed according to the microstructure in the two joints. The thicker IMC layers were observed in the DC04-AA7055 joints either before or after heat treatment, due to the faster growth rate of the θ phase. In addition, pores were left in the aluminium side near the interface as a result of the low melting point of AA7055.The modelling results for both the diffusion model and grain growth model fitted very well with the data from the static heat treatment. Grain growth occurred in both phases in the heat treatment significantly, and was found to affect the calculated activation energy by the grain boundary diffusion. At lower temperatures in the phases with a smaller grain size, the grain boundary diffusion had a more significant influence on the growth rate of the IMC phases. The activation energies for the grain boundary diffusion and lattice diffusion were calculated as 240 kJ/mol and 120 kJ/mol for the η phase, and 220 kJ/mol and 110 kJ/mol for the θ phase, respectively. The model was invalid for the growth of the discontinuous IMC layers in USW process. The diffusion model only worked for 1-Dimensional growth of a continuous layer, which was the growth behaviour of the IMC layer during heat treatment. However, due to the highly transient conditions in USW process, the IMC phases were not continuous and uniform even after a welding time of 2 seconds. Therefore, the growth of the island shaped IMC particles in USW was difficult to be predicted, unless the nucleation stage was taken into consideration.

As the electronic industry advances rapidly, the dimensions of the semiconductor products keep on being shrunk and that leads to more stringent requirement on process control and quality assurance. In particular, area array packages like BGA, CSP, flip chips, wafer bumping and wafer-level packaging need to have the 3D quality of some micro-surfaces inspected accurately and efficiently. An example of the micro-surfaces is the solder bumps for direct die-to-die bonding, which are of size as small as 60 to 600 microns in diameter. However, the tiny size and often highly specular and textureless nature of the surfaces make the inspection difficult. In addition, the size of the inspection system is required to be small so as to minimize restraint, on the operation of the various moving parts involved in the manufacturing process. / Experimental results with image data of a variety of objects have positively demonstrated the feasibility of the proposed methodology. / In the mechanism the inspection speed is governed by the number of needed images which also equals the number of spatial shiftings of the grating. This thesis also addresses how the grating, as well as its spatial shifting, can be designed optimally for minimizing this image number for faster inspection speed. An optimal solution to shifting strategy optimization is proposed that is applicable to any pattern on the fringe grating. A design method is also introduced for optimal pattern design, which has higher efficiency than brute-force searching. To reduce image number furthermore, bit-pairing codification mechanism and color-encoded pattern are proposed and verified to be more efficient. / In this thesis, I propose a new methodology for reconstructing micro-surfaces in 3D. The mechanism is based upon the familiar concept of binary structured-light, projection, but adapted, for the purpose of greatly reducing the system size, from the traditional setup of an array of multiple light sources to one with a single light source. The mechanism consists of a single light source in combination with a binary grating for projecting a binary pattern onto the target surface, and of a camera for capturing image of the illuminated scene. By shifting the binary grating in space and in every drifting taking a separate image of the illuminated surface, each position on the illuminated surface will be attached with a string of binary code over the sequence of captured images. With a suitable design of the binary grating, the binary code string can be made unique for each bump surface position, allowing exact correspondence between the binary pattern and image data, and subsequently 3D determination through triangulation. With such a bright-or-dark world for each image position, the issues of image saturation, image noise, and textureless nature of the target surfaces are avoided. / Jun Cheng. / "June 2006." / Adviser: Ronald Chi-kit Chung. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6499. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 107-117). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Submitted by LUTH SILVA RAMOS null (lutherair@yahoo.com.br) on 2017-03-29T19:49:44Z No. of bitstreams: 1 Dissertação Luth Ramos 2017 Final.pdf: 2110056 bytes, checksum: 5f14af4841d2cf0a501f307108e2e0b2 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-03-30T18:14:10Z (GMT) No. of bitstreams: 1 ramos_ls_me_guara.pdf: 2110056 bytes, checksum: 5f14af4841d2cf0a501f307108e2e0b2 (MD5) / Made available in DSpace on 2017-03-30T18:14:10Z (GMT). No. of bitstreams: 1 ramos_ls_me_guara.pdf: 2110056 bytes, checksum: 5f14af4841d2cf0a501f307108e2e0b2 (MD5) Previous issue date: 2017-01-26 / A escassez de combustíveis de origem fóssil tem preocupado setores energéticos e industriais. Outra preocupação eminente são as taxas de emissões de poluentes na atmosfera, causado pelo processo de combustão. Estes processos são responsáveis por grande parte de toda energia primária produzida no mundo. Sendo assim, os bicombustíveis tem sido uma alternativa que atende ambas as preocupações. Neste cenário, a atomização também assume uma importante função dentro da combustão de líquidos. O atomizador tem por objetivo desintegrar o combustível líquido em pequenas gotículas, misturando-se com o oxidante na proporção correta e nas condições adequadas, para produzir um processo de combustão eficiente e estável, reduzindo significativamente as formações de fuligens. O objetivo deste trabalho é realizar um estudo teórico de um atomizador do tipo jato-Y, para atomizar misturas de combustíveis com diferentes proporções de QAV-1 + farnesano, QAV-1 + etanol e farnesano + etanol, analisando experimentalmente as propriedades físico-químicas das misturas de combustíveis e teoricamente as características e a qualidade do spray gerado, fazendo uso da equação de Wigg para calcular o MMD (diâmetro médio de gotas). Através das propriedades físico-químicas das misturas de combustíveis é possível analisar possíveis alternativas de combustíveis que podem apresentar características “drop-in” e substitua parcialmente ou definitivamente o QAV-1 (querosene de aviação) atualmente consumido. Qualitativamente o spray gerado possui o MMD entre 30 e 40 µm, podendo variar de acordo com a temperatura de trabalho. Sendo assim o atomizador torna-se favorável para um processo de combustão eficiente. / The scarcity of fossil fuels has worried the energetic and industrials sectors. Concern also exists about emissions and their impact on the environment, which are a byproduct of the petroleum combustion processes. These processes account for much of the primary energy produced in the world. However, biofuels have been an alternative that meets both concerns. In this scenario, the atomization also assumes an important function in the combustion of liquids. The atomizer has goal to disintegrate the liquid fuel in small droplets to have the mixture of fuel/oxidant in the suitable ratio, to produce an efficient and stable combustion process, significantly reducing the formation of soot. The objective of this work is perform a theoretical study of one nozzle of the type Y-jet, to atomize binary mix of fuels with different ratio of jet-A1 + farnesane, jet-A1 + ethanol and farnesane + ethanol, experimentally analyzing the physicochemical properties of the mixtures of fuels and theoretically the characteristics and quality of the formed spray, using the Wigg’s equation to calculate the MMD (Mass Median Diameter). Through of the physicochemical properties of the mixtures of fuels, it’s possible to analyze possible alternatives of fuel that may have “drop-in” characteristics and partially or definitively to replace the currently consumed jet-A1 fuel. Qualitatively the formed spray has the MMD between 30 e 40 µm, however can be varied according with the temperature of work. Furthermore, the nozzle is favorable to an efficient combustion process.

A análise de dados binários é usualmente feita através da regressão logística, mas esse modelo possui limitações. Modificar a função de ligação da regressão permite maior flexibilidade na modelagem e diversas propostas já foram feitas nessa área. No entanto, não se sabe de nenhum pacote estatístico capaz de estimar esses modelos, o que dificulta sua utilização. O presente trabalho propõe uma implementação em R de quatro modelos de regressão binária com função de ligação paramétrica usando tanto a abordagem frequentista como a Bayesiana. / Binary data analysis is usually conducted with logistic regression, but this model has limitations. Modifying the link function allows greater flexibility in modelling and several proposals have been made on the field. However, to date there are no packages capable of estimating these models imposing some difficulties to utilize them. The present work develops an R implementation of four binary regression models with parametric link functions in both frequentist and Bayesian approaches.

Conjuntos de dados com respostas multivariadas aparecem frequentemente em pesquisas em que os dados são provenientes de questionários. Exemplos mais comuns são pesquisas de opinião, mais especificamente, pesquisas de marketing em que a preferência do consumidor em potencial é avaliado: pelo produto, marca, preço, praça, promoção e etc. Um tipo pesquisa de opinião que ganha grande destaque no Brasil de dois em dois anos são as pesquisas eleitorais de intenção de votos. Nós introduzimos nesta tese uma classe de modelos de regressão multivariados com funções de ligação assimétricas para o ajuste de conjuntos de dados com respostas multivariadas binárias. As funções de ligação consideradas são bastante flexíveis e robustas, contemplando funções de ligação simétricas como casos particulares. Devido a complexidade do modelo, nós discutimos a sua identificabilidade. A abordagem Bayesiana foi considerada e alguns algoritmos de Monte Carlo via Cadeia de Markov (MCMC) foram desenvolvidos. Nós descrevemos algumas ferramentas de seleção de modelos, os quais incluem o Critério de Informação da Deviance (DIC), a Pseudo-Verossimilhança Marginal e o Pseudo-Fator de Bayes. Adicionalmente, um estudo de simulação foi desenvolvido com dois objetivos; i) verificar a qualidade dos algoritmos desenvolvidos e ii) verificar a importância da escolha da função de ligação . No final da tese uma aplicação em um conjunto de dados real é considerada com o objetivo de ilustrar as metodologias e técnicas apresentadas. / Data sets with multivariate responses often appear in surveys where the data came from questionnaires. Opinion poll, sometimes simply referred to as a poll, are common examples of studies in which the responses are multivariate. One type poll that gain great prominence in Brazil in election years, is the survey of vote intent. However, despite the higher visibility of prognostic studies of election, opnion polls is a tool widely used to detect trends and positions of different social segments on various topics, be they political, social or governmental. We introduce in this work a class of multivariate regression models with asymmetric link functions to fit data sets with multivariate binary responses. The link functions here considered are quite flexible and robust, contemplating symmetrical link functions as special cases. Due to the complexity of the model, we discuss its identifiability. The Bayesian approach was considered and some Monte Carlo Markov Chain (MCMC) algorithms have been developed. Simulation studies have been developed with two objectives: i) verify the quality of the algorithms developed and ii) to verify the importance of choosing the link function. At the end of this work an application in a real data set is considered in order to illustrate the methodologies and techniques presented.

A inferência Bayesiana está cada vez mais dependente de algoritmos de simulação estocástica, e sua eficiência está diretamente relacionada à eficiência do algoritmo considerado. Uma prática bastante utilizada é a introdução de variáveis auxiliares para obtenção de formas conhecidas para as distribuições {\\it a posteriori} condicionais completas, as quais facilitam a implementação do amostrador de Gibbs. No entanto, a introdução dessas variáveis pode produzir algoritmos onde os valores simulados são fortemente correlacionados, fato esse que prejudica a convergência. O agrupamento das quantidades desconhecidas em blocos, de tal maneira que seja viável a simulação conjunta destas quantidades, é uma alternativa para redução da autocorrelação, e portanto, ajuda a melhorar a eficiência do procedimento de simulação. Neste trabalho, apresentamos propostas de simulação em blocos no contexto de modelos de regressão binária com o uso de variáveis auxiliares. Três classes de funções de ligação são consideradas: probito, logito e probito-assimétrico. Para as duas primeiras apresentamos e implementamos as propostas de atualização conjunta feitas por Holmes e Held (2006). Para a ligação probito-assimétrico propomos quatro diferentes maneiras de construir os blocos, e comparamos estes algoritmos através de duas medidas de eficiência (distância média Euclidiana entre atualizações e tamanho efetivo da amostra). Concluímos que os algoritmos propostos são mais eficientes que o convencional (sem blocos), sendo que um deles proporcionou ganho superior a 160\\% no tamanho efetivo da amostra. Além disso, discutimos uma etapa bastante importante da modelagem, denominada análise de resíduos. Nesta parte adaptamos e implementamos os resíduos propostos para a ligação probito para os modelos logístico e probito-assimétrico. Finalmente, utilizamos os resíduos propostos para verificar a presença de observações discrepantes em um conjunto de dados simulados. / The Bayesian inference is getting more and more dependent of stochastic simulation algorithms, and its efficiency is directly related with the efficiency of the considered algorithm. The introduction of auxiliary variables is a technique widely used for attainment of the full conditional distributions, which facilitate the implementation of the Gibbs sampling. However, the introduction of these auxiliary variables can produce algorithms with simulated values highly correlated, this fact harms the convergence. The grouping of the unknow quantities in blocks, in such way that the joint simulation of this quantities is possible, is an alternative for reduction of the autocorrelation, and therefore, improves the efficiency of the simulation procedure. In this work, we present proposals of simulation using the Gibbs block sampler in the context of binary response regression models using auxiliary variables. Three class of links are considered: probit, logit and skew-probit. For the two first we present and implement the scheme of joint update proposed by Holmes and Held (2006). For the skew-probit, we consider four different ways to construct the blocks, and compare these algorithms through two measures of efficiency (the average Euclidean update distance between interactions and effective sample size). We conclude that the considered algorithms are more efficient than the conventional (without blocks), where one of these leading to around 160\\% improvement in the effective sample size. Moreover, we discuss one important stage of the modelling, called residual analysis. In this part we adapt and implement residuals considered in the probit model for the logistic and skew-probit models. For a simulated data set we detect the presence of outlier used the residuals proposed here for the different models.

O presente trabalho procura investigar alguns dos processos colisionais de átomos de Rydberg ultrafrios. Utilizando uma armadilha magneto-óptica (MOT), foi possível aprisionar átomos de 85Rb, um elemento alcalino metálico, numa região da ordem de lmn a temperaturas da ordem de poucas centenas de ?K, regime chamado de \"ultrafrio\" na literatura. Os átomos de 85Rb são então excitados para estados de alto número quântico principal, também chamados de estados de Rydberg, através de um laser pulsado. Nesses estados, os átomos apresentam propriedades exageradas devido ao tamanho da órbita do elétron de valência, sendo uma delas os potenciais de longo-alcance. Em nossos experimentos, após a excitação, são detectados átomos em estados vizinhos ao originalmente excitado, evidenciando a existência de transições. Como esses estados são muito próximos em energia, a presença de potenciais de longo alcance pode fazer a energia de um par de átomos de Rydberg no seu estado inicial ficar ressonante com a energia do mesmo par numa combinação de outros estados, tornando então possível transições para esses estados. Nosso estudo visa quantificar de certa forma essas observações, assim como estimar a importância do movimento desses átomos nas transições observadas. / This dissertation seeks to address some of the characteristics of collisional processes in ultracold Rydberg atoms. With a Maqneto-Optical Trap (MOT), we trapped a sample of 85Rb, an alkaline metal element, in a region of about lmm at a temperature of a few hundreds of ?K, known in the literature as the \"ultracold\" regime. The 85Rb atoms are then excited to high principal quantum number states, also known as Rydberg states, with a pulsed laser. In these states, the atoms present exaggerated properties due to the large valence electron orbit, such as long-range potentials in our experiments, after excitation, we have detected atoms in neighboring states to the originally excited state, an evidence of atomic transitions. Since these states have similar energy, the presence of long-range potentials can make the energy of a pair of atoms in the initial state be resonant with the energy of the same pair in a combination of different states, making it possible to have transitions to these nearby states. Our work tries to quantify these observations, as well as to gauge the role of atomic movement in these transitions.

Atualmente, pode-se observar que a Lei de Moore vem estagnando. A freqüência de operação já não cresce da mesma forma, e a potência consumida aumenta drasticamente em processadores de propósito geral. Ao mesmo tempo, sistemas embarcados vêm se tornando cada vez mais heterogêneos, caracterizados por uma grande quantidade de modelos computacionais diferentes, sendo executados em um mesmo dispositivo. Desta maneira, como novas tecnologias que irão substituir totalmente ou parcialmente o silício estão surgindo, novas soluções arquiteturais são necessárias. Apesar de sistemas reconfiguráveis já terem demonstrado serem candidatos em potencial para os problemas supracitados, ganhos significativos de desempenho são alcançados apenas em programas que manipulam dados massivamente, não representando a realidade dos sistemas atuais. Ademais, o seu uso em alta escala ainda está limitado à utilização de ferramentas ou compiladores que, claramente, não mantêm a compatibilidade de software e a reutilização do código binário já existente. Baseando-se nestes fatos, a presente tese propõe uma nova técnica para, utilizando um sistema reconfigurável, otimizar tanto programas orientados a dados como aqueles orientados a controle, sem a necessidade de modificação do código fonte ou binário. Para isto, um algoritmo de Tradução Binária, que trabalha em paralelo ao processador, foi desenvolvido. O mecanismo proposto é responsável pela transformação de seqüências de instruções, em tempo de execução, para serem executadas em uma unidade funcional reconfigurável de granularidade grossa, suportando execução especulativa. Desta maneira, é possível aproveitar as vantagens do uso da lógica combinacional para aumentar o desempenho e reduzir o gasto de energia, mantendo a compatibilidade binária em um processo totalmente transparente. Três diferentes estudos de caso foram feitos: os processadores Java e MIPS R3000 – representando o campo de sistemas embarcados – e o conjunto de ferramentas Simplescalar, que simula um processador superescalar baseado no MIPS R10000 – representando o mercado de processadores de propósito geral. / As Moore’s law is losing steam, one already sees the phenomenon of clock frequency reduction caused by the excessive power dissipation in general purpose processors. At the same time, embedded systems are getting more heterogeneous, characterized by a high diversity of computational models coexisting in a single device. Therefore, as innovative technologies that will completely or partially replace silicon are arising, new architectural alternatives are necessary. Although reconfigurable computing has already shown to be a potential solution for such problems, significant speedups are achieved just in very specific dataflow oriented software, not representing the reality of nowadays systems. Moreover, its wide spread use is still withheld by the need of special tools and compilers, which clearly preclude software portability and reuse of legacy code. Based on all these facts, this thesis presents a new technique using reconfigurable systems to optimize both control and dataflow oriented software without the need of any modification in the source or binary codes. For that, a Binary Translation algorithm has been developed, which works in parallel to the processor. The proposed mechanism is responsible for transforming sequences of instructions at runtime to be executed on a dynamic coarse-grain reconfigurable array, supporting speculative execution. This way, it is possible to take advantage of using pure combinational logic to speed up the execution, maintaining full binary compatibility in a totally transparent process. Three different case studies were evaluated: a Java Processor and a MIPS R3000 – representing the embedded systems field – and the Simplescalar Toolset, a widely used toolset that simulates a superscalar architecture based on the MIPS R10000 processor – representing the general-purpose market.

This thesis describes Monte-Carlo computer simulations of binary alloys, with comparisons between small angle neutron scattering (SANS) data, and numerically integrated solutions to the Cahn-Hilliard-Cook (CHC) equation. Elementary theories for droplet growth are also compared with computer simulated data. Monte-Carlo dynamical algorithms are investigated in detail, with special regard for universal dynamical times. The computer simulated systems are Fourier transformed to yield partial structure functions which are compared with SANS data for the binary Iron-Chromium system. A relation between real time and simulation time is found. Cluster statistics are measured in the simulated systems, and compared to droplet formation in the Copper-Cobalt system. Some scattering data for the complex steel PE16 is also discussed. The characterisation of domain size and its growth with time are investigated, and scaling laws fitted to real and simulated data. The simple scaling law of Lifshitz and Slyozov is found to be inadequate, and corrections such as those suggested by Huse, are necessary. Scaling behaviour is studied for the low-concentration nucleation regime and the high-concentration spinodal-decomposition regime. The need for multi-scaling is also considered. The effect of noise and fluctuations in the simulations is considered in the MonteCarlo model, a cellular-automaton (CA) model and in the Cahn-Billiard-Cook equation. The Cook noise term in the CHC equation is found to be important for correct growth scaling properties.