Research in the field of Photonics is in part, directed at the application of light-emitting materials based on silicon platforms. In this work silicon wafers are modified by carbon ion implantation to incorporate silicon carbide, a known light-emitting material. Ion beam synthesis treatments are applied with implant energy of 20 keV, and ion fluences of 3, 5 and 10 × 1016 ions/cm2 at both ambient temperature and high temperature (400 °C). The samples are annealed at 1000 °C, after implantation. The carbon ion implanted silicon is characterized using Raman and Fourier transform infrared spectroscopic techniques, grazing-incidence X-ray diffraction, transmission electron microscopy and electron energy loss spectroscopy. The materials are observed to have a multilayer structure, where the ambient temperature implanted materials have an amorphous silicon layer, and an amorphous silicon layer with carbon-rich, nanoscale inclusions. The high temperature implanted materials have the same layers, with an additional polycrystalline Si layer at the interface between the implanted layer and the target substrate and the amorphous Si layer with SiC inclusions is reduced in thickness compared to the ambient temperature samples. The carbon-rich inclusions are confirmed to be SiC, with no evidence of carbon clusters in the materials observed using Raman spectroscopy. The carbon ion-implanted material is used to fabricate Schottky diodes having a semitransparent gold contact at the implanted surface, and an aluminum contact on the opposite side. The diodes are tested using current-voltage measurements between -12 and +15 V. No reverse breakdown is observed for any of the diodes. The turn-on voltages for the ambient temperature implanted samples are 2.6±0.1 V, 2.8±0.6 V and 3.9±0.1 V for the 3, 5 and 10 × 1016 ions/cm2 samples, respectively. For the high temperature implanted samples, the turn-on voltages are 3.2±0.1 V, 2.7±0.1 V, and 2.9±0.4 V for the implanted samples with same fluences. The diode curves are modeled using the Shockley equation, and estimates are made of the ideality factor of the diodes. These are 188±16, 224.5±5.8, and 185.4±9.2 for the ambient temperature samples, and 163.6±6.3, 124.3±5.3, and 333±12 for the high temperature samples. The high ideality factor is associated with the native oxide layer on the silicon substrate and with the non-uniform, defect-rich implanted region of the carbon ion implanted silicon. Red-orange visible light emission from the diodes is observed with voltage greater than the turn-on voltage applied across the diodes. The luminescence for the ambient temperature samples is attributed to porous silicon, and amorphous silicon. The high temperature implanted samples show luminescence associated with porous silicon, nanocrystalline silicon carbide, and defects in silicon related to ion implantation. The luminescent intensity observed for the ambient temperature samples is higher than for the high temperature samples. The dominant luminescence feature in the carbon ion-implanted silicon material is porous silicon, which is described by quantum confinement of excitons in silicon.

abstract: Amorphous oxide semiconductors are promising new materials for various optoelectronic applications. In this study, improved electrical and optical properties upon thermal and microwave processing of mixed-oxide semiconductors are reported. First, arsenic-doped silicon was used as a model system to understand susceptor-assisted microwave annealing. Mixed oxide semiconductor films of indium zinc oxide (IZO) and indium gallium zinc oxide (IGZO) were deposited by room-temperature RF sputtering on flexible polymer substrates. Thermal annealing in different environments - air, vacuum and oxygen was done. Electrical and optical characterization was carried out before and after annealing. The degree of reversal in the degradation in electrical properties of the thin films upon annealing in oxygen was assessed by subjecting samples to subsequent vacuum anneals. To further increase the conductivity of the IGZO films, Ag layers of various thicknesses were embedded between two IGZO layers. Optical performance of the multilayer structures was improved by susceptor-assisted microwave annealing and furnace-annealing in oxygen environment without compromising on their electrical conductivity. The post-processing of the films in different environments was used to develop an understanding of mechanisms of carrier generation, transport and optical absorption. This study establishes IGZO as a viable transparent conductor, which can be deposited at room-temperature and processed by thermal and microwave annealing to improve electrical and optical performance for applications in flexible electronics and optoelectronics. / Dissertation/Thesis / Ph.D. Materials Science and Engineering 2011

Philosophiae Doctor - PhD / In this thesis, regioregularpoly( 3-hexylthiophene) (rr-P3HT) polymer was used as a light absorption and electron donating material, while the C60 fullerene and its derivative [6,6]-phenyl C61-butyric acid methyl ester (PCBM) were used as electron acceptor materials. The effect of solvent to control the degree of mixing of the polymer and fullerene components, as well as the domain size and charge transport properties of the blends were investigated in detail using P3HT:C60 films. The photo-physical, structural and electrical transport properties of the polymer blends were carried out according to their ratios. A distinctive photoluminescence (PL) quenching effect was observed indicating a photo-induced electron transfer. In this thesis, the effect of solvents on the crystallization and interchain interaction of P3HT and C60 fullerene films were studied using XRD, UV-vis, PL, Raman and FTIR spectroscopy. The polymer blends formed with non-aromatic solvents exhibited an improved crystallinity and polymer morphology than that formed with aromatic solvents. An improved ordering was demonstrated in the polymer films spin coated from non-aromatic solvents. This indicates that the limited solubility of rr P3HT in a marginal solvent such as non-aromatic solvents can offer a strategy to obtain highly ordered crystal structures and lead directly to optimal morphologies on the films. / South Africa

Todo início de período letivo, gestores de instituições de ensino se deparam com um típico problema: montar as grades horárias das turmas, segundo as demandas de aulas de suas disciplinas e considerando as restrições de disponibilidade horária de todos os envolvidos. Conhecido na literatura como School Timetabling Problem (STP), este típico problema de otimização combinatória é reconhecidamente complexo por conta do seu elevado número de variáveis e restrições. Devido à dependência das regras do sistema educacional de cada país, o STP pode ter inúmeras variantes, cada uma com o seu próprio conjunto de particularidades. Este trabalho se propõe a oferecer um modelo para o STP considerando o sistema educacional brasileiro, visando alocar não apenas professores, mas também determinando que disciplina cada professor deve ministrar e alocando os locais de aula. O modelo proposto, baseado na meta-heurística simulated annealing, foi concebido para que cada instituição de ensino usuária tenha liberdade para definir a penalidade de cada tipo possível de inconformidade ou restrição, de modo que o algoritmo empregado possa encontrar uma solução com o menor custo possível. / Every beginning of term, educational institution managers face a typical problem: planning the classes' timetable, according to their lesson demands for each subject, considering, furthermore, the schedule constrains of all actors. Known as school timetabling problem (STP), this typical combinatorial optimization problem is remarkably complex due to the high number of variables and constraints. Owing to the rules of each country's educational system, STP can have uncountable variants, each one with their own set of features. This dissertation searches to offer a model to STP considering the Brazilian Educational System, focusing on allocating not only the teachers but also determining which subject each teacher should teach and allocating classrooms, laboratories and the like. The propesed model, based on the metaheuristic simulated annealing, was conceived so that each educational institution using this model has the freedom to define which penalty will be applied to each possible kind of noncomformity and constraint, in order for the applied algorithm to find a solution at the lowest cost as possible.

Quantum annealing is expected to be a powerful generic algorithm for solving hard combinatorial optimization problems faster than classical computers. Finding the solution to a combinatorial optimization problem is equivalent to finding the ground state of an Ising Hamiltonian. In today's quantum annealers the spins of the Ising Hamiltonian are mapped to superconducting qubits. On the other hand, dissipation processes degrade the success probability of finding the solution. In this thesis we set out to explore a newly proposed architecture for a noise-resilient quantum annealer that instead maps the Ising spins to continuous variable quantum states of light encoded in the field quadratures of a two-photon pumped Kerr- nonlinear resonator based on the proposal by Puri et al. (2017). In this thesis we study the Wigner negativity for this newly proposed architecture and evaluate its performance based on the negativity of the Wigner function. We do this by determining an experimental value to when the presence of losses become too detrimental, such that the Wigner function of the quantum state during the evolution within the anneal becomes positive for all times. Furthermore, we also demonstrate the capabilities of this continuous variable quantum annealer by simulating and finding the best solution of a small instance of the NP-complete subset sum problem and of the number partitioning problem.

Submitted by Maykon Nascimento (maykon.albani@hotmail.com) on 2015-10-19T19:19:50Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Modelo matematico e meta heuristica simulated annealing para elaboração de roteiros turísticos com base no tourist trip design problem.pdf: 2271247 bytes, checksum: faaad9e85f6978197ce7c7b03933a2ca (MD5) / Approved for entry into archive by Elizabete Silva (elizabete.silva@ufes.br) on 2015-11-03T19:59:38Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Modelo matematico e meta heuristica simulated annealing para elaboração de roteiros turísticos com base no tourist trip design problem.pdf: 2271247 bytes, checksum: faaad9e85f6978197ce7c7b03933a2ca (MD5) / Made available in DSpace on 2015-11-03T19:59:38Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Modelo matematico e meta heuristica simulated annealing para elaboração de roteiros turísticos com base no tourist trip design problem.pdf: 2271247 bytes, checksum: faaad9e85f6978197ce7c7b03933a2ca (MD5) Previous issue date: 2015 / O turismo é um importante setor para economia mundial e vem crescendo consistentemente nos últimos anos. Porém, um fator determinante para escolha do destino de um turista é a existência de pontos de interesse que ele deseja visitar na região e, para tanto, as informações dos pontos de interesse de uma região devem estar disponíveis. Dada às limitações de tempo do turista, não é possível para ele visitar todos os atrativos e, por essa razão, se faz necessário a criação de roteiros turísticos. Muito embora existam diversos pacotes de viagens com destinos predefinidos, contemplando locais mais populares, nos últimos anos tem crescido a procura por soluções que criem roteiros personalizados voltados às necessidades de cada turista. Para suprir essa nova demanda, Van Oudheusden e Vansteenwegen (2007) propuseram o Tourist Trip Design Problem (TTDP) e sugeriram o uso do Orienteering Problem (OP) e suas extensões para resolução do TTDP. Esta dissertação tem por objetivo o desenvolvimento de um modelo matemático e de uma meta-heurística Simulated Annealing (SA) para resolução do TTDP. O objetivo considerado consiste em gerar roteiros que maximizem a soma das notas atribuídas aos atrativos em função do grau de interesse do turista, levando em conta o período que ele tem disponível na localidade e o horário que cada atrativo está disponível para ser visitado. / Tourism is an important sector for the world economy and has been growing steadily over recent years. However, a decisive factor for the choice of a tourist destination is the existence of points of interest in the region he wants to visit and, therefore, the information from points of interest in a region should be available. Given the tourist time constraints, it is not possible for him to visit all the attractions and, therefore, it is necessary the creation of tourist routes. Although there are several packages with predefined destinations contemplating most popular locations in recent years has increased the demand for solutions that create custom tours for the needs of each tourist. To meet this new demand Van Oudheusden and Vansteenwegen (2007) proposed the Tourist Trip Design Problem (TTDP) and they suggested that the use of the Orienteering Problem (OP) and its extensions is the best approach to the TTDP. This thesis proposes the development of a mathematical model and a Simulated Annealing (SA) metaheuristic to solve the TTDP. The objective considered is to generate routes that maximize the sum of scores awarded to the attractions based on the degree of interest of the tourist taking into account the time that he has in the locality and the time that each attraction is available to be visited.

Fatores críticos no controle de um sistema elétrico, sem dúvida alguma, são os desafios de manter-se toda a sua estrutura física em plenas condições de operação. A infra-estrutura passiva, materiais e acessórios, devem manter suas propriedades elétricas e mecânicas, minimizados aos impactos da descaracterização por excedentes de correntes elétricas circulantes. Um dos elementos passivos nas redes de distribuição de energia elétrica é motivo deste estudo, sendo o condutor de corrente elétrica, por meio de fios de cobre eletrolíticos – ETP C110 têmpera meio-duro, seção circular, 101% IACS. As condições operacionais dos fios de cobre instalados numa rede estão sujeitos a intensidade da corrente elétrica de trabalho em períodos e eventos diversos; as correntes podem variar desde a mínima corrente de carga, carga média, carga pesada, sobrecarga ou sobrecorrentes por curto circuitos; todos esses eventos são relacionados a difusidade térmica do material, sendo relacionado para cada um deles uma temperatura obtida. No total foram investigadas 6 amostras, sendo 5 delas denotando um evento de intensidade de corrente elétrica, objetivando apontar os resultados das análises realizadas sobre os efeitos da temperatura imposta pela corrente elétrica circulante em fios. As amostras, originadas de produto, “material base” foram caracterizados, em fio de cobre nu rígido de diâmetro de 4,515 mm (≈16,00 mm²), utilizando-se dispositivo gerador de corrente elétrica, produziu-se intensidade da mesma para cada espécime; cinco amostras foram caracterizadas, sendo respectivamente, em 143 Amper (capacidade nominal do fio), 214.5 Amper, 286 Amper, 400 Amper e 700 Amper; cada qual denotando um evento com duração de tempo específica, sendo efetuado o monitoramento do gradiente de temperatura, individualmente, obtendo-se como resultado estruturas de material recristalizado, bem como produtos com recozimento severo. Inicialmente foi investigada a composição química percentual do material encruado pelo processo de trefilação do cobre puro ETP, e também a tração unidirecional e obtenção da estrutura metalográfica de todas as amostras, bem como a resistividade/condutibilidade de ambas. / Critical factor in the control of an electrical system, undoubtedly, are the provocation in maintain it all your physical structure in total operation conditions. Static infrastructure, materials and complement, must to maintain it’s electrical and mechanicals proprieties reduced at impacts loss characteristic for excess of electrical current. One of those statics elements in the electrical power distribution system it’s reason this work, being conductor of electrical current, through de electrolytic copper wire – ETP C110 hardness half-hard, cross-section, 101% IACS. Operations conditions of the copper wire installed in network are subjects to intensity of electrical current in cycle and several events; the currents can alter it from current minim, middle, absolute, overload or short circuit; all those events it’s connected to thermal diffusity of material, being connected to each and all a temperature have achieved. In total was investigated six samples, being five indicating an event of intensity of electrical current, intending obtain results of the analyses made with effects of temperature achieved by electrical current in wires. The samples, made of “base material” were characterized, in copper wire, without isolation, hardness half-hard, diameter 4.515mm (≈16,00 mm²), using it electrical current generator device, makes to circulate intensity of electrical current for each sample; five sample was characterized, being respectively, 143 Amper (nominal capacity of product), 214.5 Amper, 286 Amper, 400 Amper e 700 Amper; every one denoting an event with specific duration, being made the monitoring temperature rate of change, individually, obtaining as resulted structure of recrystallized material, and too severe annealing. Previously was investigated the percentage chemical composition of hardened material by drawing process of pure copper ETP, and too unidirectional tensile strength and metallography of all sample, and too the resistivity/conductivity in every one.

Made available in DSpace on 2014-06-11T19:32:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-08-15Bitstream added on 2014-06-13T20:23:37Z : No. of bitstreams: 1 almeida_hl_dr_rcla.pdf: 806140 bytes, checksum: 7940276ecd62a931d89c15464ccc97db (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A zona de cisalhamento Itapetim (ZCI) desenvolveu foliação e lineação nos diferentes tipos de rochas, milonitos a ultramilonitos. Muitos dos tipos de microestruturas observadas na ZCI preservam evidências de condições metamórficas de alto grau e baixo grau de temperatura. O padrão das orientações preferenciais dos eixos [c] de quartzo, obtida a partir de agregados policristalinos deformados, mostra dois diferentes tipos de simetrias, guirlandas do tipo I e simples. A análise da textura sugere partição da deformação com cisalhamento coaxial e não coaxial na ZCI. Um veio de quartzo mineralizado em ouro encaixado em rocha ultramilonítica, constitui a zona de precipitação hidrotermal. O veio é bandado por segmentos de turmalina, o qual inclui agregados de grãos de quartzo maciço entre as bandas. Os grãos de quartzo mostram contatos poligonais e restritos limites intumescentes. O último sugere recristalização dinâmica por migração de limite de grão e os grãos poligonais (microestrutra em espuma) são melhor explicados por annealing. Os padrões de eixos [c] de quartzo obtido no veio aurífero é idêntico ao observado nos ultramilonitos da ZCI. Este padrão é interpretado como uma textura preservada formada durante o cisalhamento não coaxial. A estrutura bandada é interpretada como o resultado de variações da pressão de fluidos e a formação microfraturas, associadas a eventos de crack-seal. Mecanismos de crack-seal foram ativos antes ou durante a deformação da ZCI. As feições microestruturais suportam evidências para a última possibilidade. / The Itapetim shear zone(ISZ) developed both foliation and lineation in the different rock types, from mylonites to ultramylonites. Most of the microstructure types observed in the ISZ preserve evidence of high temperature metamorphic conditions. The quartz [c]-axis, of deformed polycrystalline aggregates, show two distinct symmetries, type I crossed girdles and single girdles. The geometrical analysis of texture, suggest non-coaxial shear for deformation in ISZ. A gold mineralized quartz vein hosted in ultramylonitic rocks, constitutes the hydrothermal precipitation zone. The vein is banded by tourmiline segments, which include massive quartz grains aggregates between the bands. The quartz grains show polygonal contacts and minor intumescent limits. These latter suggest grain boundary migration recrystallization and the polygonal grains seem to be best explained by the annealing after stopping the shear deformation. The quartz [c]-axis obtained in the auriferous vein shows the same single girdle pattern observed in the ultramylonites of the ISZ. This pattern is interpreted as a preserved texture formed during the shear deformation. The banded structure is interpreted as the result of variations of the fluid pressure and the formation of microfractures, associated the crack-seal events. Crack-seal mechanisms can have been active previous or during the deformation of the IZS. The microstructurals features supports evidences for the last possibility.

Fatores críticos no controle de um sistema elétrico, sem dúvida alguma, são os desafios de manter-se toda a sua estrutura física em plenas condições de operação. A infra-estrutura passiva, materiais e acessórios, devem manter suas propriedades elétricas e mecânicas, minimizados aos impactos da descaracterização por excedentes de correntes elétricas circulantes. Um dos elementos passivos nas redes de distribuição de energia elétrica é motivo deste estudo, sendo o condutor de corrente elétrica, por meio de fios de cobre eletrolíticos – ETP C110 têmpera meio-duro, seção circular, 101% IACS. As condições operacionais dos fios de cobre instalados numa rede estão sujeitos a intensidade da corrente elétrica de trabalho em períodos e eventos diversos; as correntes podem variar desde a mínima corrente de carga, carga média, carga pesada, sobrecarga ou sobrecorrentes por curto circuitos; todos esses eventos são relacionados a difusidade térmica do material, sendo relacionado para cada um deles uma temperatura obtida. No total foram investigadas 6 amostras, sendo 5 delas denotando um evento de intensidade de corrente elétrica, objetivando apontar os resultados das análises realizadas sobre os efeitos da temperatura imposta pela corrente elétrica circulante em fios. As amostras, originadas de produto, “material base” foram caracterizados, em fio de cobre nu rígido de diâmetro de 4,515 mm (≈16,00 mm²), utilizando-se dispositivo gerador de corrente elétrica, produziu-se intensidade da mesma para cada espécime; cinco amostras foram caracterizadas, sendo respectivamente, em 143 Amper (capacidade nominal do fio), 214.5 Amper, 286 Amper, 400 Amper e 700 Amper; cada qual denotando um evento com duração de tempo específica, sendo efetuado o monitoramento do gradiente de temperatura, individualmente, obtendo-se como resultado estruturas de material recristalizado, bem como produtos com recozimento severo. Inicialmente foi investigada a composição química percentual do material encruado pelo processo de trefilação do cobre puro ETP, e também a tração unidirecional e obtenção da estrutura metalográfica de todas as amostras, bem como a resistividade/condutibilidade de ambas. / Critical factor in the control of an electrical system, undoubtedly, are the provocation in maintain it all your physical structure in total operation conditions. Static infrastructure, materials and complement, must to maintain it’s electrical and mechanicals proprieties reduced at impacts loss characteristic for excess of electrical current. One of those statics elements in the electrical power distribution system it’s reason this work, being conductor of electrical current, through de electrolytic copper wire – ETP C110 hardness half-hard, cross-section, 101% IACS. Operations conditions of the copper wire installed in network are subjects to intensity of electrical current in cycle and several events; the currents can alter it from current minim, middle, absolute, overload or short circuit; all those events it’s connected to thermal diffusity of material, being connected to each and all a temperature have achieved. In total was investigated six samples, being five indicating an event of intensity of electrical current, intending obtain results of the analyses made with effects of temperature achieved by electrical current in wires. The samples, made of “base material” were characterized, in copper wire, without isolation, hardness half-hard, diameter 4.515mm (≈16,00 mm²), using it electrical current generator device, makes to circulate intensity of electrical current for each sample; five sample was characterized, being respectively, 143 Amper (nominal capacity of product), 214.5 Amper, 286 Amper, 400 Amper e 700 Amper; every one denoting an event with specific duration, being made the monitoring temperature rate of change, individually, obtaining as resulted structure of recrystallized material, and too severe annealing. Previously was investigated the percentage chemical composition of hardened material by drawing process of pure copper ETP, and too unidirectional tensile strength and metallography of all sample, and too the resistivity/conductivity in every one.

Made available in DSpace on 2016-12-08T17:19:37Z (GMT). No. of bitstreams: 1 Resumo.pdf: 10956 bytes, checksum: b3ab8ff2ededda1434fbc70325d132f4 (MD5) Previous issue date: 2010-12-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Semi-processed electrical steels require annealing after processing in the motors manufactures to improve motors efficiency by reducing losses and increasing permeability. Annealing in fully processed electrical steel is performed to relax the residual stress and promote recovery or recrystallization of distorted parts. Commercial samples from different steels with different chemical compositions were selected to evaluate the influence of final annealing heat treatment temperature and dew point on the magnetic properties, the carbon content and grain size increase. Were performed with annealing atmosphere without steam and with dew point of 5, 10, 20 and 25°C at temperatures of 760 and 790°C. Magnetic losses, relative permeability, carbon content, grain size and mechanical properties measurements were made in addition to the evaluation of the microstructure to determine this influence. It was observed in the semi-processed steel with 300 ppm carbon content, which with dew point increase the carbon content reduce the grain size increase and improve magnetic properties. In the other steels studied, reducing the dew point improved the magnetic properties, but the atmosphere without steam has improved only fully processed steel with 2% silicon. It was found that in fully processed steels the best results were obtained with annealing temperature of 790°C. / Aços elétricos semiprocessados necessitam de recozimento após a sua manufatura para melhorar o rendimento dos motores com a redução das perdas magnéticas e aumento da permeabilidade. os aços totalmente processados o recozimento é realizado para relaxar as tensões residuais e promover a recuperação ou recristalização das partes deformadas. Amostras comerciais de diferentes aços com variadas composições químicas foram selecionadas para avaliar a influência do ponto de orvalho e temperatura de recozimento final nas propriedades magnéticas, no teor de carbono e no aumento do tamanho de grão. Foram realizados recozimentos com atmosfera sem vapor e com ponto de orvalho de 5, 10, 20 e 25°C, nas temperaturas de 760 e 790°C. Medições de perdas magnéticas, permeabilidade, teor de carbono, tamanho de grão e propriedades mecânicas, além da avaliação da microestrutura, foram efetuados para determinar esta influência. Foi verificado no aço com 300 ppm de carbono, que com aumento do ponto de orvalho reduziu o teor de carbono, aumentou o tamanho de grão e melhorou as propriedades magnéticas. Nos demais aços estudados, a redução do ponto de orvalho melhorou as propriedades magnéticas, porém com ausência de umidade somente houve melhora no aço totalmente processado com 2% de silício. Foi verificado ainda que nos aços totalmente processados os melhores resultados foram obtidos com a temperatura de recozimento de 790°C.