Thesis (M.S. in materials science and engineering)--Washington State University, August 2009. / Title from PDF title page (viewed on Aug. 7, 2009). "School of Mechanical and Materials Engineering." Includes bibliographical references (p. 44-46).

Thesis (Ph.D.)--University of Delaware, 2009. / Principal faculty advisor: Joseph I. Daniel, Dept. of Economics. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1961. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 41-43).

Post-implant annealing of InP and GaInAs is usually accomplished using thermal cycles of 10-30 minutes duration; this thesis reports the results of a systematic study of an alternative technique, 'rapid thermal annealing' (RTA), in which the implanted material is held at elevated temperatures for less than 180 seconds. Results were obtained using Hall-effect measurements, Rutherford backscattering (RBS), secondary ion mass spectrometry (SIMS), and photoluminescence (PL), amongst other methods. Iron-doped InP, implanted with magnesium, zinc or mercury was subjected to RTA and five different methods of protecting the InP surface were compared: the use of an indium-tin pseudobinary leads to tin incorporation and n-type surface layer formation above 700°C; encapsulating layers of phosphosilicate glass, SiO2, Si3N4 or a novel 'dual' layer of Si3N4/AlK may lead to p-type, semi-insulating or n-type behaviour. This is shown to be due to the indiffusion of silicon from these encapsulants into the implanted substrate; this indiffusion is enhanced by implantation damage. RTA in a phosphine ambient gives the best surface protection at elevated temperatures, but leads to substantial outdiffusion and loss of the implanted dopant. Electrically active p-type layers were successfully obtained from both zinc and mercury implants. GaInAs was implanted with beryllium, magnesium, zinc and mercury and electrically active p-type layers obtained following magnesium implantation; electrical results were, however, dominated by the quality of the starting material and not reproducible. 'Proximity' annealing under a GaAsP or GaAs cover piece gave adequate surface protection for GaInAs at annealing temperatures up to 800°C. The presence of an amorphous layer In InP and GalnAs is shown to be detrimental and the maximum amorphous thickness which can be fully regrown is found to be about 250 nm at 750 °C. It is suggested that solid phase epitaxy of thicker amorphous layers is inhibited by the local nucleation of microcrystallites within the remaining amorphous material and a model describing the regrowth of III-V compounds is presented. Substantial redistribution of the implanted dopant occurs during RTA of InP and GalnAs, the shape of dopant profiles is modified by both the residual damage present within the material and the form of surface protection employed. Several models of acceptor diffusion in iron-doped InP are compared and discussed.

A necessidade de redução de custos de produção torna o caster mais vantajoso que o processo de placas, porém a aplicação dos produtos obtidos via vazamento contínuo é limitada pelas condições microestruturais. A alta taxa de resfriamento no processo de vazamento, que pode ultrapassar 300 °C/s, resulta em uma condição de supersaturação dos elementos em solução sólida. Quando as chapas são recozidas, ocorre precipitação na forma de dispersóides que atrasam a recristalização. Quando o material obtido via caster segue o processo convencional de placas laminadas a quente, com recozimento intermediário e têmpera obtida por reduções pré-definidas, o resultado é uma chapa com aspecto superficial e desempenho na estampagem prejudicados pela granulação grosseira. Para otimizar o processo é necessário aprimorar o conhecimento dos fenômenos de encruamento, recuperação, recristalização e crescimento de grãos além de relacioná-los aos processos industriais. A prática usual de processo para o material de caster consiste em um tratamento térmico de homogeneização para precipitar os elementos em solução sólida e melhorar a distribuição dos precipitados para que existam núcleos viáveis para a recristalização. O processo de homogeneização agrega um elevado custo na produção de chapas e pode ser substituído em determinadas aplicações por um tratamento de recristalização parcial que evita o crescimento de grãos. Para o presente trabalho, as amostras foram retiradas de rolos caster brutos de fusão e de placas laminadas a quente, nas ligas AA1200 e AA3003. As bobinas foram laminadas a frio até 0,88 mm e as amostras sofreram tratamentos térmicos em temperaturas entre 150 e 500 °C, com intervalos de 50 °C. O intervalo entre 200 e 450 °C foi melhor detalhado e os tratamentos térmicos foram feitos a cada 10 °C. Todos os tratamentos tiveram duração de 1 hora. Após tratamentos, foram feitas medidas de condutividade elétrica e dureza, ensaios de tração, Erichsen, análises químicas e caracterização microestrutural. O decréscimo das propriedades mecânicas em função do aumento da temperatura do tratamento térmico mostra o efeito da recuperação e recristalização nas amostras de chapas. A evolução das propriedades em função da temperatura é diferente quando se compara caster e placa, devido principalmente à taxa de resfriamento durante o vazamento do caster que mantém os elementos em solução sólida. A diferença é muito mais acentuada na liga AA3003, devido à baixa solubilidade sólida do manganês no alumínio, que precipita durante o tratamento térmico e atrasa a recristalização. Com a evolução das propriedades mecânicas em função da temperatura foi possível determinar a faixa ideal de tratamento térmico para a obtenção das têmperas objetivadas. / The necessity of reducing productions costs makes the continuous casting more advantageous than plates process, however, the application of the products obtained through continuous casting is limited by microstructural conditions. The high rate of cooling in the continuous casting, which can exceed 300 °C/s, results in a condition of supersaturation of the elements in solid solution. When the plates are annealed, precipitation occurs in the form of dispersoids that delays the recrystallization. When the continuous casting material follows the conventional process of hot-rolled plates, with intermediate annealing and hardness achieved by pre-defined reductions, the result is a plate with superficial appearance and performance in drawing hampered by the coarse graining. To optimize the process is necessary to improve the knowledge of the phenomena of cold working, recovery, recrystallization and grain growth in addition to relate them to industrial processes. The practice of process for continuous casting material consists in homogenization heat treatment to precipitate elements in solid solution and improve the distribution of precipitates in order to provide viable nuclei for the recrystallization. The process of homogenization adds a high cost in the production of plates and can be replaced in certain applications for treatment of partial recrystallization that prevents the grain growth. For this paper, the samples were taken from continuous casting rolls as cast and hot-rolled plates, in the alloys AA1200 and AA3003. The coils were cold-rolled up to 0.88 mm and the samples have undergone thermal treatment at temperatures between 150 and 500 °C, with intervals of 50 °C. The interval between 200 and 450 °C was better detailed and heat treatments were performed every 10 °C. All treatments had duration of 1 hour. After treatment, measures of electrical conductivity and hardness were made, besides traction tests, Erichsen, chemical analysis and microstructural characterization. The decrease of mechanical properties as a function of increasing heat treatment temperature shows the effect of recovery and recrystallization in samples of hot-rolled plates. The development of properties depending on the temperature is different when continuous casting and hot-rolled plates are compared, mainly due to the rate of cooling during the casting that keeps the elements in solid solution. The difference is more pronounced in the alloy AA3003, due to the low solid solubility of manganese in aluminum, which precipitates during the heat treatment and delays the recrystallization. With the evolution of mechanical properties according to the temperature, it was possible to determine the optimal range of heat treatment to obtain the desired hardness.

The output from a ruby laser was homogenized, and used to laser anneal the active layer of GaA1As double heterostructure wafers in an attempt to improve the radiative efficiency of the active layer. At anneal energies exceeding the estimated threshold for melting of the active layer, the radiative efficiency was reduced by a factor of two. Subsequently, semiconductor laser diodes fabricated from laser annealed heterostructures performed much worse than those fabricated from unannealed heterostructures. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Estimativas das tensões de barras e das perdas de potência em alimentadores primários de distribuição são sempre necessárias. Entretanto, o número de medições que são disponíveis para fazer isso é muito pequeno. Normalmente, são feitas medições apenas na saída da subestação e nas barras onde estão conectados consumidores especiais. Nas outras barras, que são a grande parte do sistema, só se têm informações sobre a potência nominal dos transformadores ali instalados. Neste trabalho, propõe-se um método de estimação de estado de alimentadores de distribuição, ou seja, de determinação dos valores aproximados das tensões de barras e das perdas técnicas totais. Para isso, realiza-se um ajuste das cargas comuns (exceto as cargas especiais) mediante estimação de fatores de potência e fatores de utilização. Para cada ponto de medição disponível (P, Q, V e I), calcula-se um fator de potência e um fator de utilização que será atribuído às cargas a jusante daquele ponto. O cálculo desses fatores de potência e de utilização é feito utilizando-se um algoritmo simulated annealing, as medidas disponíveis e os valores dos transformadores de distribuição instalados nas barras. O método foi aplicado aos alimentadores-teste do IEEE de 13, 34, 37 e 123 barras e a validação é feita a partir da comparação dos valores obtidos com os valores conhecidos dos resultados desses alimentadores.

The goal of this research project was to develop a new implant annealing process using silane overpressure to maintain crystal integrity. After ion implantation the surface of the SiC wafer is damaged due to high energy of the implant ions. In addition the doping activation is very low. To overcome these problems a new implant annealing process was developed to rectify the surface damage and increase the dopant activation. SiC implant annealing was performed in the silicon carbide (SiC) chemical vapor deposition (CVD) reactor in the Emerging Materials Research Laboratory (EMRL) at Mississippi State University. A process was developed to eliminate surface step bunching, which is evident in argon annealed crystals. The process gas used in the new technique was silane (3 % SiH4 in 97% UHP Ar). The anneal run time was 30 minutes with argon flow rate at 6 slm and silane flow rate at 6 sccm. SiC material (n and p type epitaxial layers) and devices (JBS Diodes and LDMOSFET?s) were annealed using the silane over pressure developed during this research. The process results were characterized using tools such as optical micrograph, capacitance-voltage (C-V), Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). These characterization tools were mainly used to determine the surface roughness of the SiC crystal and the dopant activation after annealing. As compared to an Ar anneal, the SiC material and devices annealed in the silane ambient had a better surface. An empirical process chemistry model was developed to support the experimental results. The model developed showed that the partial pressure of Si is greater than the vapor pressure of SiC in the substrate. Thus it is believed that the partial pressure of Si suppressed any Si out-diffusion from the SiC substrate, thereby maintaining the crystal surface integrity. The model also provided silane flow rates for higher temperature anneals which may be necessary to fully activate other ion species.

No description available.

Orientador: Romero Lázaro, Rubén Augusto / Banca: Marcos Julio Rider Flores / Banca: Eduardo Nobuhiro Asada / Resumo: Os problemas de corte ótimo são considerados como clássicos dentro da pesquisa operacional, dado sua grande área de aplicação na industria e sua alta complexidade matemática e computacional. Um dos problemas mais conhecidos desta classe é o chamado Cutting Stock Problem, o qual permite dividir uma placa em varias peças de diversos tamanhos, com a finalidade de obter a configuração que maximize a área da placa que está sendo utilizada. Dado o nível de dificuldade e a grande quantidade de aplicações deste problemas em diversas áreas, existe muito interesse em criar novos procedimentos eficientes para resolver este tipo de problemas. Nesta dissertação, é apresentado o estado da arte dos diversos problemas de corte bidimensional de peças retangulares em uma única placa, em varias placas e em rolos, considerando a possibilidade de rotacionar as peças em um ângulo de 90 e com restrições de corte tipo não-guilhotinado. Além disso, são descritas as abordagens matemáticas aplicadas pelos diversos pesquisadores dedicados a resolver estes problemas. Este trabalho está focado em resolver exclusivamente o Cutting Stock Problem com e sem rotação de peças. Portanto, é proposto um tipo de codificação binária com vista a ser aplicada neste tipo de problema e resolvê-lo mediante o uso do algoritmo heurístico Bottom-Left, em conjunto com a metaheurística Simulated Annealing. Finalmente, para comprovar a eficiência da metodologia apresentada, foram utilizados alguns casos de estudo da literatura especializada, com diferentes níveis de complexidade. Para cada caso, são apresentados os resultados obtidos e é realizada uma comparação dos métodos de solução propostos para resolver o Cutting Stock Problem com e sem rotação de peças. / Abstract: The problems of optimal cutting are considered as classic within the operational research, given their large area of application in industry and their high computational and mathematic complexity. One of the most well-known of this kind of problem is called the Cutting Stock Problem, which allows to divide a plate in several pieces of various sizes, in order to obtain the configuration that maximizes the area of the plate being used. Given the level of difficulty and the large number of applications of this problem in several areas, there is interest in creating new efficient procedures for solving this kind of problem. In this dissertation, it is presented the state of the art of the two-dimensional cutting problems of rectangular pieces on a single plate, in several plates and rollers, considering the possibility of rotating the pieces at an angle of 90 in which the cuts are restricted to non-guillotined type. Furthermore, the mathematical approaches applied by different researchers dedicated to solving these problems are described. This work is focused exclusively on solving the Cutting Stock Problem with and without rotating pieces. Therefore, a kind of binary encoding in order to be applied to this kind of problem and to solving it through the use of the Bottom-Left heuristic algorithm in conjunction with Simulated Annealing are proposed. Finally, to prove the efficiency of the presented methodology, some study cases from the specialized literature were used, with different levels of complexity. For each case, the results are presented and a comparison of the proposed solution methods for solving the Cutting Stock Problem with and without rotating pieces is performed. / Mestre