Made available in DSpace on 2014-10-09T12:41:22Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:21Z (GMT). No. of bitstreams: 0 / Custo e durabilidade ainda são os maiores impeditivos para a entrada das células a combustível no mercado de dispositivos usados para produção de eletricidade. Assim, o objetivo deste trabalho foi avaliar a durabilidade dos conjuntos eletrodo-membrana-eletrodo (MEAs) produzidos no IPEN pelo método de impressão à tela para uso em células a combustível do tipo PEM. Para tanto, foi necessário desenvolver um protocolo adequado de teste de durabilidade de longa duração, visando obter estimativas da taxa de queda do potencial elétrico da célula a combustível ao longo do tempo e, assim, fazer inferência a respeito do tempo de vida deste dispositivo. Os MEAs testados durante este estudo foram preparados pelo método de impressão à tela com catalisador de Pt/C comercial e membrana Nafion® 115. O aprimoramento do protocolo de teste de durabilidade de longa duração se deu pela escolha dos procedimentos a serem executados e pelo ajuste de alguns parâmetros de operação da célula a combustível, tais como temperatura da célula, fluxo de H2 e fluxo de O2. Para a análise dos dados obtidos com os testes, foram aplicados métodos estatísticos de ajuste de modelos e curvas de polarização. Além disso, amostras da camada catalítica de um dos MEAs utilizados nos testes de durabilidade de longa duração foram analisadas por meio de microscopia eletrônica de transmissão (MET) para serem comparadas com amostras da camada catalítica de um MEA de controle. Para se avaliar o desempenho global da célula a combustível do tipo PEM em operações de longa duração, um dos grandes desafios foi fazer a separação entre as componentes de perda de desempenho que são reversíveis das irreversíveis. As estimativas obtidas para a taxa de queda do potencial elétrico da célula a combustível ao longo do tempo variaram num intervalo de 108,19 a 318,15 μV.h-1. Estes resultados podem ser considerados satisfatórios quando comparados com valores apresentados na literatura. Finalmente, as imagens obtidas por MET mostraram uma tendência de aumento no tamanho médio das partículas Pt em decorrência do tempo de operação dos MEAs, mas que não implicou numa queda significativa do desempenho das células a combustível do tipo PEM testadas. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Submitted by Priscila Monalisa Peruggia (monalisa_peruggia@hotmail.com) on 2018-05-25T15:19:57Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tese versão digital_NARA.pdf: 2811545 bytes, checksum: 00831e5d65c1a3a2ae5ff2bda42167d7 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2018-05-25T15:51:43Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tese versão digital_NARA.pdf: 2811545 bytes, checksum: 00831e5d65c1a3a2ae5ff2bda42167d7 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2018-05-25T15:55:57Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tese versão digital_NARA.pdf: 2811545 bytes, checksum: 00831e5d65c1a3a2ae5ff2bda42167d7 (MD5) / Made available in DSpace on 2018-05-25T15:55:57Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tese versão digital_NARA.pdf: 2811545 bytes, checksum: 00831e5d65c1a3a2ae5ff2bda42167d7 (MD5) Previous issue date: 2018-04-04 / FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas / Brazilian higher education fieldin the last decades has experienced a significant increase in vacancies, number of enrollments, opening of universities, new courses, and restructuring of existing ones. In this expansion scenery new policies were implemented in the schools in order to give more opportunities to young people from low class participating in this education’s level. This study is part of the field of education sciences and public policies and it was proposed to analyze the situation of the young people of popular classes in public higher education in Amazonas, taking into account access policies’ and permanence of the students at Federal University of Amazonas, in Institute of Health and Biotechnology - located in the Middle Solimões (Instituto de Saúde e Biotecnologia - Campus do Médio Solimões). In order to get to know questions related to the access and permanence of these young people who entered the ISB during the period of 2010 - 2016, this study was carried out with 50 students who were enrolled in the six ISB courses, 05 professors and 06 administrative technicians. The process of collecting data was done through the application form and semi-structured interview with the three groups of participants. Methodological approach that guided this study was the model of the four poles of Bruyne, Herman and Schoutheete (1977). The analytical treatment of the data was carried out in a critical and dialectical perspective from the integration of qualitative and quantitative approaches. This study made possible to have clearness on the impact of the access and permanence of students from popular classes who entered the undergraduate courses of the Institute during 10 years of existence. Data revealed a reality of higher education that receives students from various locations, an expressive participation of young people in the age of 18 to 24 years old. Most of these students are included to the programs and actions that help their staying in the University. Based on the participants’ statements, it was observed that internalization has actually widened the access of young people from popular classes and the aid under the National Program of Student Assistance is indispensable for the permanence of these students in higher education, such as, housing, academic and food. Participants pointed out retention and abandonment as emotional and financial problems caused by distancing of their families from other localities and deficiencies in schooling process from previous levels. In this understanding, it is accepted that the expansion of youth participation in higher education must be followed by political measures that can face challenges due to social inequalities that these students will have to face at when their insertion in the university. In a different situation, the project of democratization of this education’s level in the popular classes becomes impracticable. / O campo da Educação Superior brasileira experimentou, nas últimas décadas, um aumento expressivo no que se refere à oferta de vagas, número de matrículas, abertura de novos cursos, criação de universidades e reestruturação das já existentes. Neste cenário de expansão, muitas regulamentações foram implementadas no interior das instituições de ensino com o fim de ampliar a participação de jovens das camadas populares neste nível de ensino. Este estudo se insere no campo das ciências da educação e políticas públicas e se propõe a analisar a situação do jovem de camadas populares no Ensino Superior público do Amazonas a partir da materialidade das políticas de acesso e de permanência implementadas no âmbito da Universidade Federal do Amazonas e no interior do Instituto de Saúde e Biotecnologia – Campus do Médio Solimões. Para o aprofundamento das questões relacionadas ao acesso e à permanência desses jovens que ingressaram no ISB no período analisado (2010 a 2016), realizou-se um estudo de campo que envolveu 50 discentes matriculados nos seis cursos do ISB, além de 05 docentes e 06 técnicos administrativos. Os dados foram coletados por meio da aplicação de um formulário com os discentes e de entrevista semiestruturada com os três grupos. O caminho metodológico que norteou a abordagem do sistema de análise foi o modelo dos quatro polos das práticas metodológicas de Bruyne, Herman e Schoutheete (1977). O tratamento analítico dos dados foi realizado numa perspectiva crítica e dialética a partir da integração das abordagens qualitativa e quantitativa. O estudo possibilitou o conhecimento de alguns mecanismos que, ao longo desses 10 anos de existência do ISB, incidem diretamente no acesso e na permanência de estudantes de camadas populares que ingressaram nos cursos de graduação do Instituto. Os dados revelaram uma realidade de Ensino Superior que recebe estudantes de várias localidades, apontando para uma expressiva participação de jovens na faixa etária de 18 a 24 anos. Grande parte desses estudantes estão vinculados aos programas e às ações que auxiliam na sua permanência na universidade. Com base nos depoimentos dos grupos participantes, constatou-se que a interiorização ampliou de fato o acesso de jovens das camadas populares e que os auxílios executados no âmbito do Programa Nacional de Assistência Estudantil são indispensáveis à permanência desses alunos no Ensino Superior, sobretudo, o auxílio moradia, acadêmico e Restaurante Universitário. Dentre as principais causas de retenção e abandono dos cursos apontadas pelos grupos, destacou-se: os problemas emocionais e financeiros dos estudantes acarretados pelo distanciamento das famílias dos jovens oriundos de outras localidades e as deficiências no processo de escolarização acumuladas dos níveis anteriores. Nesse entendimento, admite-se que a ampliação da participação do jovem na Educação Superior deve ser acompanhada por medidas políticas que possam fazer frente aos desafios que, por força das desigualdades sociais, esses estudantes terão que enfrentar quando forem inseridos nos meios universitários; caso contrário, o projeto de democratização desse nível de ensino nas camadas populares sofrerá inúmeras e profundas limitações.

Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2016-12-19T19:27:02Z No. of bitstreams: 2 Dissertação - Luis Fernando Miyazaki Namba - 2016.pdf: 8743418 bytes, checksum: a5ea1100c56d418c97d9f60f3f3ef0b5 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-12-26T13:15:10Z (GMT) No. of bitstreams: 2 Dissertação - Luis Fernando Miyazaki Namba - 2016.pdf: 8743418 bytes, checksum: a5ea1100c56d418c97d9f60f3f3ef0b5 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-12-26T13:15:10Z (GMT). No. of bitstreams: 2 Dissertação - Luis Fernando Miyazaki Namba - 2016.pdf: 8743418 bytes, checksum: a5ea1100c56d418c97d9f60f3f3ef0b5 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-11-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This paper presents a methodology of three-phase induction machine in steady state, called Field Propagation Theory (FPT). The FPT is based on the engine division into layers and application of Maxwell’s equations, this methodology is able to consider the magnetic saturation and anisotropy of electrical steel and relate it to the motor equivalent circuit. The FTP has proposed two variations machine equation: The Induced Current Method (ICM) and the Predefined Current Method (PCM) which differ for the mode of obtaining the rotor current. To validate the TPC used two three-phase induction motors. The results of the proposed method were compared to those presented by the Finite Element Method (FEM) and were very promising. / Este trabalho apresenta uma metodologia de análise da máquina de indução trifásica em regime permanente, denominada Teoria de Propagação do Campo (TPC). A TPC é baseada na divisão do motor em camadas e na aplicação das equações de Maxwell. Esta metodologia é capaz de considerar a saturação magnética e a anisotropia do aço elétrico e relacioná-la ao circuito elétrico equivalente do motor. Dentro da TPC foram propostas duas variações de equacionamento da máquina: o Método de Corrente Induzida (MCI) e o Método de Corrente Pré-definida (MCP) que se diferem pela forma de obtenção da corrente presente no rotor. Para a validação da TPC utilizou-se dois motores de indução trifásicos de pequeno porte. Os resultados da metodologia proposta se mostraram muito promissores quando comparados aos apresentados pelo Método dos Elementos Finitos (MEF).

Submitted by Neusa Fagundes (neusa.fagundes@unioeste.br) on 2018-02-27T12:17:38Z No. of bitstreams: 2 Talita_Quadros2017.pdf: 3672889 bytes, checksum: 662c90d816bac4e44956db64813b9097 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-02-27T12:17:38Z (GMT). No. of bitstreams: 2 Talita_Quadros2017.pdf: 3672889 bytes, checksum: 662c90d816bac4e44956db64813b9097 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-08-21 / The present research comes from the need of promoting reflection on an important aspect of the teaching/ learning process of linguistic analysis: the use of elements that delimit positioning. This justification promoted a study on the performance of modals elements in excerpts from texts of elementary and middle school students from a countryside public school in a city from Parana State. It was based on the analysis of the collected material in the databank of the projects Theoretical Application and Reflection in the Classroom: linguistic analysis as a support for the production of texts from students of a public school in the State of Paraná (ART) and Diagnostics and Theoretical Application in Classroom: verification of the performance and evaluation of the teaching of linguistic analysis and textual production of high school students of a public school in the State of Parana (DAT). The basic and qualitative research was subsidized by authors dealing with linguistic modality, such as Castilho and Castilho (1992), Neves (2006), Corbari (2008/2013), Koch (2009) and Sella (2011). This course, based on the definition of study focus, theoretical reference reading, data collection and interpretation of the data collected, motivated to verify in the analyzed excerpts how the modal pair “é + adjetivo” and the verb can indicates points of view that sometimes are linked to the most internal and sometimes to the most external layers of significance. The goal is to interpret the occurrence of these modalities on text excerpts written by students who participated in the aforementioned projects, as well as to verify the degree of producers’ engagement with the expressed content which were expressed through these structures. The layers verification allowed us to evaluate the engagement degree established with the propositional content. This study also allowed us to notice established notions of emphasis and attenuation on the analyzed which leads to articulations that indicate negotiations of points of view. / A presente pesquisa nasce da necessidade de promover reflexão sobre aspecto importante do processo ensino-aprendizagem da análise linguística: o emprego de elementos que demarcam posicionamento. Essa justificativa impulsionou estudo sobre a atuação dos modalizadores em recortes de textos de alunos do ensino fundamental e médio, de escola pública do campo de uma cidade do Estado do Paraná. Partiu-se da análise de material coletado no banco de dados dos projetos Aplicação e Reflexão Teórica na Sala de Aula: análise linguística como suporte para a produção de textos de alunos de uma escola pública do Estado do Paraná (ART) e Diagnósticos e Aplicação Teórica em Sala de Aula: verificação do rendimento e avaliação do ensino de análise linguística e produção textual de alunos do ensino médio de uma escola pública do Estado do Paraná (DAT). A pesquisa básica e de cunho qualitativo foi subsidiada por autores que tratam da modalização linguística, como Castilho e Castilho (1992), Neves (2006), Corbari (2008/2013), Koch (2009) e Sella (2011). Esse percurso, pautado em definição de foco de estudo, leitura de referencial teórico, coleta de dados e interpretação dos dados coletados, motivou verificar nos recortes analisados como os modalizadores par é + adjetivo e verbo poder indicam pontos de vista ora vinculados a camadas mais internas, ora a camadas mais externas da significação. Objetivou-se interpretar ocorrências dos modalizadores em tela em recortes de textos de estudantes participantes dos projetos supracitados, além de verificar o grau de engajamento dos produtores com o conteúdo enunciado, expresso por meio de tais estruturas. A verificação dessas camadas proporcionou avaliar o grau de engajamento estabelecido com o conteúdo proposicional. Este estudo permitiu observar que os modalizadores em análise estabelecem noções de ênfase e de atenuação, o que aponta para articulações que indicam negociações de ponto de vista.

Esta dissertação visa analisar a representação do relacionamento entre os intelectuais de esquerda e as camadas populares na obra cinematográfica Quase dois irmãos (Lúcia Murat, 2005). O filme representa, a partir de uma narrativa dramática, aspectos fundamentais das relações entre a classe média e as camadas populares. Através de três espaços temporais, década de 1950, 1970 e anos 2000, o contato entre a classe média e o morro carioca, são representadas as perspectivas dos intelectuais de esquerda referente a aproximação com o povo entre décadas de 1950 e 1970. O golpe militar de 1964 interromperia o momento de construção de projeto cultural de revolução social engendrado pelos intelectuais de esquerda, acirrando as tensões existentes entre os dois ethos sociais. Esta pesquisa busca compreender como essa construção ficcional, enquanto criação artística da diretora Lucia Murat, sedimenta na forma cinematográfica determinada compreensão do mundo, conectada à memória da ditadura militar de setores da esquerda brasileira. Configura-se uma fonte documental importante pela experiência histórica que está condensada em sua narrativa, assim como em sua estrutura estética que ratifica os movimentos históricos de permanência e cisão expostos no filme e possibilita reflexões sobre relações e problemas sociais e raciais no Brasil. / This dissertation aims to analyze the representation of the relationship between the left intellectuals and the popular strata in the cinematographic \"Almost brothers\" (Lúcia Murat, 2005). The film represents, from a dramatic narrative, fundamental aspects of the relationships between the middle class and the popular strata. Through three timelines, the 1950, 1970 and 2000 years, the contact between the middle class and the carioca Hill, are represented the perspectives of left-wing intellectuals for rapprochement with the people between 1950 and 1970 decades. The military coup of 1964 would interrupt the moment of construction of cultural project of social revolution engendered by leftist intellectuals, intensify existing tensions between the two social ethos. This research seeks to understand how this fictional construct, while artistic creation of director Lucia Murat, forms a sediment in cinematic form determined understanding of the world, connected to the memory of the military dictatorship of sectors of the brazilian left. Configures a document source important for historical experience that is condensed into your narrative, as well as in your aesthetic structure that ratifies the historical movements of permanence and spin-off exposed in the film and provides reflections on relationships and problems racial and social in Brazil.

The paper is concerned with the Nitsche mortaring in the framework of domain decomposition where non-matching meshes and weak continuity of the finite element approximation at the interface are admitted. The approach is applied to singularly perturbed reaction-diffusion problems in 2D. Non-matching meshes of triangles being anisotropic in the boundary layers are applied. Some properties as well as error estimates of the Nitsche mortar finite element schemes are proved. In particular, using a suitable degree of anisotropy of triangles in the boundary layers of a rectangle, we derive convergence rates as known for the conforming finite element method in presence of regular solutions. Numerical examples illustrate the approach and the results.

L'industrie nucléaire publique et militaire génère une quantité importante d'effluents liquides radioactifs qu'il faut traiter avant leur rejet dans l'environnement. Des procédés de décontamination alternatifs aux techniques industrielles (évaporation, traitement chimique) sont en cours de développement, comme par exemple le traitement en colonne ou le couplage filtration/sorption. Une partie des recherches associées à ces techniques de décontamination porte sur l'élaboration et la mise en forme de sorbants spécifiques. Dans ce contexte, les objectifs de cette thèse étaient d'une part d'étudier la synthèse en milieu CO2 supercritique (SC) de films de TiO2 déposés sur des supports macroporeux et d'autre part d'évaluer leur potentiel d'extraction dans ces procédés alternatifs. Une méthode de synthèse reproductible a été mise au point, basée sur la décomposition thermique de l'isopropoxyde de titane en milieu CO2 SC entre 150°C et 350°C. Dès 150°C, cette méthode permet la réalisation de films de TiO2 nanostructurés et adhérents sur des supports macroporeux en céramique (mousses, supports tubulaires en alumine α). L'effet de la température de synthèse de ces matériaux sur leurs caractéristiques physico-chimiques et leurs propriétés de sorption a été étudié sur des poudres de TiO2 élaborées dans les mêmes conditions que les films supportés. Les meilleures performances de sorption ont été observées pour la poudre obtenue à 150°C, du fait de sa plus grande densité de sites de surface par rapport aux poudres élaborée à 250°C et 350°C. Cette température de synthèse (150°C) a donc été sélectionnée pour l'étude détaillée des sorbants composites (TiO2/supports) afin d'évaluer leurs performances de sorption dans les procédés de traitement en continu. Les essais de sorption en colonne ont montré qu'une mousse en alumine macroporeuse (Φpore=400µm) revêtue de TiO2 est adaptée pour traiter des effluents en mode dynamique à fort débit. La taille des macropores et la hauteur de colonne sont des paramètres importants à maitriser. Pour le traitement par filtration/sorption, les membranes de TiO2 présentent une bonne résistance mécanique et sont capables d'extraire le strontium en mode dynamique. D'autre part dans le cas du strontium, les sorbants composites (TiO2/mousse ou TiO2/support tubulaire) sont régénérables à 100% à l'aide d'une solution aqueuse acidifiée (pH=3). / Public and military nuclear industry generates a significant amount of radioactive liquid waste which must be treated before being released into the environment. Decontamination methods alternative to the industrial techniques (evaporation, chemical treatment) are being developed, such as column treatments or coupled filtration/sorption processes. Current researches mainly focus on the development and shaping of specific sorbents. In this context, the objectives of this thesis were first to study the synthesis of TiO2 layers on macroporous ceramic supports in supercritical (SC) CO2 and then to evaluate their potential for radionuclide extraction in these alternative processes. A robust synthesis method has been developed, based on the thermal decomposition of titanium isopropoxide in SC CO2 in the temperature range between 150°C and 350°C. Nanostructured TiO2 films were formed on the macroporous supports (ceramic foams, tubular α-alumina supports) with good adhesion, already at 150°C. The effect of the synthesis temperature on sorbents physico-chemical characteristics and sorption properties has been studied with TiO2 powders prepared under the same conditions as the supported films. The best sorption performance were observed for the powder prepared at 150°C, owing to its higher density of surface sites in comparison with powders prepared at either 250°C or 350°C. Consequently, this synthesis temperature (150°C) was selected for a detailed study of the composite sorbents (TiO2/support), in order to assess their sorption performance in continuous treatment processes. The sorption experiments have shown that a column of alumina macroporous foam (Φpore = 400μm) coated with TiO2 was suitable for processing effluents in dynamic mode with high throughputs. Both macropore sizes and column height were revealed as important parameters to be controlled. For the coupled filtration/sorption treatment, TiO2 membranes exhibit good mechanical strength and are able to extract strontium. On the other hand in the case of strontium, composite sorbents (TiO2/foam or TiO2/tubular support) can be fully regenerated by using an acidic aqueous solution (pH = 3).

To create a digital model of the surface of some object from a setof points, representing positions on the surface of this object, requiresinformation about the relationship between the points. This informa-tion is not immediatly accessible. Thus, for creating such a model itis necessary to establish relationsships between the points of the set.In addition, it should be possible to render the resulting modelas efficiently as possible. Modern graphics cards offer to send vertexinformations as triangle strips; by using triangle strips the informationabout the triangles can be compressed.This work is about a method for retrieving information about therelations between points in an unstructered spatial point set and trans-forming this information into triangle strips. It is based on the convexlayers of a planar point set and an algorithm for triangulating theannuli of the convex layers, which uses the Rotating Calipers.

The requirement for reduced jet noise in order to meet stringent noise legislation (civil aviation), and low infra-red observability and the use of unconventional exhaust nozzle configurations to improve aircraft survivability and performance (military aviation) is driving research to develop a better understanding of jet development and mixing mechanisms. One option open to the engineer is the use of small-scale model testing to investigate jets flows and provide valuable data for the validation of numerical models. Although more economical than large/full scale testing, additional factors that influence jet development may be present which would not be present at full scale and whose influence needs to be fully understood in order to allow small scale–large scale read-across. One such factor is the nozzle exit boundary layer. Although considerable data exist on the influence of nozzle exit boundary layers on low speed jet flows, current information on high speed jet flows is limited. It was, therefore, the aim of this thesis to extend the current understanding of nozzle exit boundary layers and their influence on the jet development for high speed jet flows through a combination of experimental and computational techniques. A combination of pneumatic probe measurements and Laser Doppler Anemometry (LDA) was used to investigate nozzle inlet and exit boundary layers of simple conical nozzles and the influence of adding a parallel extension piece. The measurements showed that the rapid acceleration of the boundary layer within the nozzle significantly reduced its momentum thickness Reynolds number and changed the state of the boundary layer from turbulent to laminar-like. The addition of a parallel extension to the nozzle exit returned the boundary layer to a fully turbulent state. A low Reynolds number RANS CFD approach was used to investigate the flow within the nozzle. Simulations using the Launder-Sharma low Reynolds number k–ε model revealed that the magnitude of the acceleration within the conical nozzles resulted in the boundary layer beginning to relaminarise. Full relaminarisation was not achieved due to the short axial distance over which the acceleration was sustained. The addition of a parallel extension provided a relaxation region in which the boundary layer could recover from the acceleration to become fully turbulent. Measurements of the jet plume originating from nozzles with laminar-like and turbulent boundary layers showed little influence of the boundary layer shape and thickness on shear layer spreading and jet centreline development.

Vertical-cavity surface-emitting lasers (VCSELs) are complex multi-layer structures whose operating characteristics are highly sensitive to variations in layer thickness and composition. They contain an active region of one or more quantum wells sandwiched between highly reflecting mirrors. Non-destructive optical characterisation techniques including reflectance spectroscopy, spectroscopic ellipsometry and photomodulated reflectance have been used to examine these structures and various components of them. In addition, the relatively novel technique of photomodulated spectroscopic ellipsometry has been examined in comparison with photomodulated reflectance in the characterisation of bulk, multi-layer and quantum well material. The distributed Bragg reflectors of VCSELs provide the high reflectance required over a selected wavelength range. Optical measurements were used to determine important information concerning layer thicknesses and compositions, which were confirmed with X-ray diffraction and transmission electron microscopy. The techniques were also used to provide important information concerning growth and uniformity, which could be readily applied for feedback to growers or for device fabrication. Novel reflectance and photomodulated reflectance measurements made on a range of laser structures designed to operate over a range of wavelengths from 650 nm to 1 ?m were used to examine the characteristics of the reflectors and the active region of the lasers. The cavity mode observed clearly indicates the lasing wavelength, and the interaction of the cavity and quantum well has been interpreted using new lineshapes. The cavity mode and quantum well resonance observed in photomodulated reflectance has been shown to provide a clear indication of where devices can be fabricated successfully from non-uniform material. The identification of the cavity and quantum well features has also enabled important information concerning the changes in structure and therefore in device performance with temperature and pressure. Measurements have also been able to provide important information to explain the variation in performance of some devices.