Dissertations / Theses on the topic 'TZM - SiC'

Ces travaux de thèses ont pour objectif de présenter les résultats obtenus sur l'assemblage de deux couples de matériaux métal - céramiques par thermocompression : Inconel®625 / Alumine et TZM / Carbure de silicium. Elle se place dans la continuité des résultats obtenus sur des assemblages similaires, au sein du laboratoire IRCER, en étudiant la faisabilité de liaisons direct et de liaison après préoxydation de la partie métallique. Une partie est dédiée à la compréhension du mécanisme d’oxydation de l’inconel®625 en utilisant une thermobalance à insertion à chaud. A l’aide des cinétiques obtenues, le mécanisme d’oxydation est alors proposé et les conditions de préoxydation pour la partie d’assemblage suivante ont pu être déterminées. Ensuite au cours de ce manuscrit sont rapportés les procédés utilisés et les résultats obtenus après variations de paramètres tels que la température ou le temps de palier de traitement thermique sur les assemblages des deux couples. L'absence de formation d'une interphase pour le couple Inconel®625 / Alumine et la formation d'une interphase complexe pour le couple TZM / Carbure de silicium permette de proposer deux études différentes de liaison céramique- métal. Une partie est également consacrée à la caractérisation de la liaison obtenue, dans chaque cas, afin de déterminer sa tenue et expliquer ses propriétés à l'aide de la microscopie électronique à balayage mais aussi une simulation numérique pour le couple Inconel®625 / Alumine et des tests de tractions pour le couple TZM / Carbure de silicium
This work has for objective to present the results obtained for the ceramic-metal bonding by hot-pressing in two cases: Inconel®625 / Alumina and TZM / Silicon carbide. All the thesis take place according to the last results obtained for similar bonding, in the laboratory IRCER, by studying the feasibility of direct bonding and bonding after pre-oxidising the metal part. A part of this study is then dedicated to the oxidation behaviour of inconel®625 under CO2 using a thermobalance with a sample hot introduction. Using the oxidation kinetics obtained, the reaction mechanism is proposed and the conditions for the metal pre-oxidation determined.Then during the manuscript are presented the processes and the results obtained after variations of parameters such as temperature and the heat treatment time for the two couples of materials. The absence of inter-phase formation in the couple Inconel®625 / Alumina and the formation of a complex inter-phase in the couple TZM / Silicon carbide allow us to propose two studies with different metal-ceramic bonding.A last part is dedicated to the characterization and the understanding of the bonding obtained in each case. To explain the properties of the samples obtained we used scaning electron microscopy but also numerical simulation for the first couple Inconel®625 / Alumina and tensile test for the second couple TZM / Silicon carbide

Over the last few years, TEM has become a powerful technique to study cracks and specially crack tips. However, the number of publications including TEM results has not grown as it was expected. The main reason for this might be difficulties in the sample preparation. In this work we present a novel FIB sample preparation technique which has proved to be an ideal tool for preparing cross sectional samples containing crack tips. The morphology of intergranular stress corrosion cracking (IGSCC) has been investigated in Alloy 600 subjected to constant load and slow strain rate tests in simulated primary circuit pressurized water reactor conditions. Cracks were observed to nucleate at high-angle grain boundaries and propagate to depths of a few tens of micrometer along such boundaries, still in the initiation stage. Electron diffraction, energy dispersive x-ray (EDX) and electron energy loss spectroscopy (EELS) have been used to identify the different corrosion products and precipitates. Elemental mapping was employed to reveal changes in composition in the crack tip area. Major observations at cracks and grain boundaries include: the presence of different oxides in different locations, differences in grain boundary oxides and open crack/free surface oxides. These observations suggest that IGSCC involves oxygen diffusion through a porous oxide region along grain boundaries to the bare metal. This is a novel concept that offers an alternative to previous mechanisms proposed in the literature e.g. H embrittlement, slip-dissolution, etc., for which no supporting evidence has been found.

Silicon carbide is a promising wide bandgap semiconductormaterial for high-temperature, high-power, and high-frequencydevice applications. However, there are still a number offactors that are limiting the device performance. Among them,one of the most important and critical factors is the formationof low resistivity Ohmic contacts and high-temperature stableSchottky diodes on silicon carbide.

In this thesis, different metals (TiW, Ti, TiC, Al, and Ni)and different deposition techniques (sputtering andevaporation) were suggested and investigated for this purpose.Both electrical and material characterizations were performedusing various techniques, such as I-V, C-V, RBS, XRD, XPS,LEED, SEM, AFM, and SIMS.

For the Schottky contacts to n- and p-type 4H-SiC, sputteredTiW Schottky contacts had excellent rectifying behavior afterannealing at 500 ºC in vacuum with a thermally stableideality factor of 1.06 and 1.08 for n- and p-type,respectively. It was also observed that the SBH for p-type SiC(Φ_Bp) strongly depends on the choice the metal with alinear relationship Φ_Bp= 4.51 - 0.58Φ_m, indicating no strong Fermi-level pinning.Finally, the behavior of Schottky diodes was investigated byincorporation of size-selected Au nano-particles in Ti Schottkycontacts on silicon carbide. The reduction of the SBH isexplained by using a simple dipole layer approach, withenhanced electric field at the interface due to the small sizeof the circular patch (Au nano-particles) and large differenceof the barrier height between two metals (Ti and Au) on both n-and p-SiC.

For the Ohmic contacts, titanium carbide (TiC) was used ascontacts to both n- and p-type 4H-SiC epilayers as well as onAl implanted layers. The TiC contacts were epitaxiallydeposited using a co-evaporation method with an e-beam Tisource and a Knudsen cell for C₆₀, in a UHV system at low substrate temperature(500 ºC). In addition, we extensively investigatedsputtered TiW (weight ratio 30:70) as well as evaporated NiOhmic contacts on both n- and p-type epilayers of SiC. The bestOhmic contacts to n-type SiC are annealed Ni (>950ºC)with the specific contact resistance of ≈ 8× 10^-6Ω cm²with doping concentration of 1.1 × 10^-19cm^-3while annealed TiW and TiC contacts are thepreferred contacts to p-type SiC. From long-term reliabilitytests at high temperature (500 ºC or 600 ºC) invacuum and oxidizing (20% O₂/N₂) ambient, TiW contacts with a platinum cappinglayer (Pt/Ti/TiW) had stable specific contact resistances for>300 hours.

Keywords: silicon carbide, Ohmic and Schottky contacts,co-evaporation, current-voltage, capacitance-voltagemeasurement, power devices, nano-particles, Schottky barrierheight lowering, and TLM structures.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Literatura, Florianópolis, 2012
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O presente trabalho focaliza as maneiras como o Diabo é apresentado na literatura brasileira contemporânea especificamente nos contos O hóspede, de Frei Betto, Eu e Bebu na hora neutra da madrugada, de Rubem Braga, Alma, vendo e Belzebu.com, de Luis Fernando Veríssimo, Lênin desce aos infernos, de Paulo Coelho e Nostalgia do amor ausente, de Walmor Santos. Na busca para o alcance do objetivo proposto pesquisou-se as três formas principais como Satã aparece na literatura e na teologia, que são apresentadas nos três primeiros capítulos, a saber: a face de anjo, a face de besta e a face humana. No quarto capítulo é feita a análise dos contos supracitados enfocando com qual das faces propostas na pesquisa o Diabo é apresentado. Verificou-se ainda que este personagem passou por diversas metamorfoses ao longo da história e, apesar de ter perdido o poder de impor o medo, continua sendo importante no meio teológico bem como um dos maiores personagens da literatura de todos os tempos.

Abstract : This paper focuses on the ways that the Devil is presented in contemporary brazilian literature specifically tales O hóspede, of Frei Betto, Eu e Bebu na hora neutra da madrugada, of Rubem Braga, Alma, vendo and Belzebu.com, of Luis Fernando Veríssimo, Lênin desce aos infernos, of Paulo Coelho and Nostalgia do amor ausente, of Walmor Santos. In seeking to achieve the proposed objective was investigated three main ways as Satan appears in literature and theology, which are presented in the first three chapters, namely: the angel face, the face of the beast and the human face. In the fourth chapter the analysis is made of the afore mentioned tales focusing on which of the proposed faces in the research presented is the Devil. It was also found that,this,character,has.gone,through several metamorphoses throughout history and despite having lost the power to impose fear, remains important amid theological as well as one of the greatest literary characters of all times

SiC is a material currently under consideration to be used in future generations of fission and fusion reactors where it will be subjected to high temperatures and significant fluxes of energetic neutrons. The work reported in this thesis aims to answer some outstanding issues of the behaviour of SiC at high temperature during irradiation by high-energy neutrons in combination with a build-up of helium (from both transmutation reactions and by direct implantation). These processes have been simulated by in-situ ion-irradiation / TEM at the MIAMI and JANNuS facilities. This thesis contains the results of experiments which investigated the nucleation and growth of helium bubbles in SiC and the behaviour of these helium bubbles under high energy heavy ion-irradiation. Our conclusions are that helium bubbles in SiC are extremely stable at high temperatures and during high-energy ion-irradiation. However, we have discovered that there is a significant effect on the bubbles attributable to either electron beam irradiation alone or the synergistic effect of the electron beam and ionirradiation which causes helium bubbles to shrink.

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Esta disserta??o tem como principal objetivo examinar aquele que pode ser considerado o termo fundamental da sem?ntica tomista: o conceito de exist?ncia. O Aquinate, em sua Teologia natural, utiliza os termos Deus e Exist?ncia como estritamente sin?nimos. Desse modo, cabe evidenciar os aspectos mais importantes de sua reflex?o metaf?sica, a fim de chegar ao conceito de Deus como A Exist?ncia (Ipsum esse subsistens). S?o Tom?s, para atingir esse resultado, deve demonstrar que, se todos os entes acess?veis ? percep??o humana existem por outro (ab alio), ent?o deve haver pelo menos um ser que exista por si (ens a se). ? este ser que responde pela causa primeira de tudo o mais que se possa afirmar, com verdade, que exista, no sentido forte do termo.

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Many discussions about the role of the school are on the agenda, in an increasingly complex society. Sociologists, educators, anthropologists, researchers of different areas seek that role. The objective of this dissertation is to contribute what we can consider the central role for the physics teaching, citizenship training. We have elaborated a didactic proposal to increase the interest of high school students on issues of social relevance and, throughout it, to promote the formation of attitudes of social responsibility, enhancing the formation of a more politically and socially active citizen. For the preparation of the proposal, studies were made on education for citizenship and on attitudes change, using as its main theoretical foundation the researches on the Science, Technology and Society curricular emphasis. The teaching of Nuclear Physics was integrated to our proposal, due to its pedagogical potential for the discussion of social, political and economic subjects related to scientific concepts and associated technologies. The educational proposal we have produced was applied on a high school class of a private school at Natal-RN. It was composed from the controversial issue involving the installation of nuclear power plants in Brazilian northeast. The methodology of role playing, in which students assumed social roles and produced specific subsidies for a public hearing and a later referendum, both simulated. In the analysis of the implementation of the proposal, we highlighted the difficulties but also the possibilities and the relevance of exercising skills such as reasoning, finding information, and arguing about of social problems. The results of the research showed the possibility of meaningful learning on Nuclear Physics contents, through this social, political, economic, scientific and technological contextualization using a controversial and real issue together with mechanisms that trigger for greater popular participation, as public hearing. It has also been identified changes in attitude by some students about issues related to Nuclear Physics. We hope, through this dissertation, to contribute to the formation of future citizens as well as to the initiative of teachers-researchers with pedagogical aims similar to those in the present work
Muitas discuss?es sobre o papel da escola est?o em pauta, em uma sociedade cada vez mais complexa. Soci?logos, educadores, antrop?logos, pesquisadores de diferentes ?reas procuram estabelecer esse papel. O objetivo desta disserta??o ? contribuir com o que se pode considerar o papel central para o ensino da F?sica: a forma??o para cidadania. Foi elaborada uma proposta de interven??o visando a despertar o interesse de alunos do Ensino M?dio para quest?es de relev?ncia social e, por meio dela, estimular posturas e atitudes de responsabilidade social, potencializando a forma??o de um cidad?o mais ativo pol?tica e socialmente. Nessa perspectiva, foram feitos estudos sobre forma??o para a cidadania e sobre mudan?as de atitude, utilizando como principal referencial te?rico a ?nfase curricular Ci?ncia, Tecnologia e Sociedade. O ensino da F?sica Nuclear foi integrado a essa proposta, em fun??o de seu potencial pedag?gico na discuss?o de quest?es sociais, pol?ticas e econ?micas, articulada com conceitos cient?ficos e tecnologias associadas. A proposta de ensino foi aplicada em uma turma de Ensino M?dio de escola particular da cidade de Natal-RN e fez uso da quest?o controversa que envolve a implanta??o das usinas nucleares no Nordeste. A metodologia de jogo de pap?is propiciou aos alunos assumirem personagens sociais espec?ficos e constru?rem conhecimentos para dar subs?dios ? realiza??o de uma audi?ncia p?blica e, posteriormente, de um plebiscito, ambos simulados. Na an?lise da implementa??o da proposta, ressaltam-se as dificuldades, mas tamb?m as possibilidades e a relev?ncia do exerc?cio de habilidades como as de argumenta??o, busca de informa??es, e discuss?o de problemas sociais. Os resultados da pesquisa mostraram a possibilidade de aprendizado significativo de conte?dos da F?sica Nuclear, por meio da atividade, que constituiu um exemplo de ensino de F?sica com contextualiza??o social, pol?tica, econ?mica, cient?fica e tecnol?gica, utilizando, no caso, uma quest?o controversa real associada a mecanismos que despertam para maior participa??o popular, como a audi?ncia p?blica. Identificam-se tamb?m mudan?as de postura por parte de alguns alunos em rela??o a assuntos referentes ? F?sica Nuclear. Espera-se, com a disserta??o, contribuir para a forma??o de futuros cidad?os bem como com a iniciativa de outros professores-pesquisadores que apresentem objetivos de ensino similares aos assumidos no trabalho

All Mobile Network Operators (MNOs) as well as international carriers are moving voice services from the legacy Public Switched Telephone Network (PSTN) to Voice over IP (VoIP). The benefit is that VoIP traffic can be easily rerouted at any moment, thus giving companies a variety of options as traffic can be rerouted to any carrier of choice leading to different Quality of Service (QoS) levels (and thus agreements) as well as different prices to choose from. With a fierce competition for the telecom companies involved in the voice traffic hubbing business, this new landscape offers not only opportunities but also opens the system to vulnerabilities. The stakes are actually quite high: If harm can be done to one of these international carriers, other companies will route away their traffic. The result will be significant financial damages for the company as well as a serious harm to its reputation. The aim of this paper is to raise awareness that internationalcarriers and in particular their VoIP traffic can be exposed to debilitating attacks to harm these systems that are critical for our everyday life. The experimentation in this project demonstrates with a hands-on example how a major carrier can be hacked and rendered useless. In particular, we craft a framework for testing the security of interconnects between MNOs and international carriers. The central point of the paper will be to demonstrate how easy it can be to attack major carriers in the market: using common open source tools without having any information in advance. Moreover, the goal is to understand how the market functions, how interconnects between companies are built, where the weaknesses are, and which solutions can thwart those threats and secure these systems.

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This work aimed to develop a thematic approach within a CTS (Science-Technology-Society) focus to physics teaching, dealing with the issue of "Electric Energy Production". The CTS focused teaching approaches scientific knowledge in the technological and social context of the learner and relates it to their everyday experiences, leading them to reflect on historical, ethical, political and socioeconomic aspects, and thus providing skills and values that help them to take responsible decisions and attitudes. In our case, the proposal was applied in a public school in the city of Angra dos Reis, in the State of Rio de Janeiro, to be evaluated and reworked according to the needs verified. The theme was chosen to be worked in this place, because the city houses the only nuclear power plant in Brazil, being a subject of extreme importance for the population and that allows the CTS approach with emphasis on the reality of the students. However, the approach was not restricted to the nuclear power plant, but involved all means of producing electric energy, such as hydroelectric, thermoelectric, with its variations of fuels, wave power plant, solar power plants and wind power plants, so that the general theme Production Of Electric Energy was divided into three sub-themes: Hydroelectric Plants, Other Modes of Energy Production and Nuclear Plants. The objective of this approach, besides teaching physical concepts involved in the processes of electric energy production, is also to make students aware of the risks, consequences and benefits of each mode of production, to have them reflect and evaluate the most to be able to actively participate in decision-making processes involving such issues. The final product of this work is a didactic sequence with varied didactic methods and resources, to serve as a guide for other teachers who wish to adopt the proposal. The text presents a brief history of science education in Brazil, its peculiarities and needs that justify the proposal and also presents the CTS movement and its main characteristics, that guide this work. The methodology adopted was the Action-research, which allowed the readjustment of the proposal throughout its application. The results were very promising and showed that the teaching of physics with a CTS approach, practiced through a thematic approach focused on students' reality, can be a means to promote a quality scientific education and to train citizens able to understand the world and the Society in which they live.
Este trabalho teve como objetivo desenvolver uma proposta de abordagem tem?tica com enfoque CTS (Ci?ncia-Tecnologia-Sociedade) para o ensino de f?sica, abordando o tema ?Produ??o de Energia El?trica?. O ensino com enfoque CTS aborda os conhecimentos cient?ficos no contexto tecnol?gico e social do educando e o relaciona com suas experi?ncias cotidianas, levando-o a refletir sobre aspectos hist?ricos, ?ticos, pol?ticos e socioecon?micos, fornecendo assim habilidades e valores que o auxiliem na tomada de decis?es respons?veis e atitudes. No nosso caso, a proposta foi aplicada em uma escola p?blica da cidade de Angra dos Reis, no Rio de Janeiro, para que fosse avaliada e reelaborada de acordo com as necessidades verificadas. O tema foi escolhido para ser trabalhado neste local, pois a cidade abriga a ?nica usina nuclear do Brasil, sendo um assunto de extrema import?ncia para a popula??o e que possibilita o enfoque CTS com ?nfase na realidade dos alunos. Por?m, a abordagem n?o ficou restrita ? usina nuclear, mas envolveu todos os meios de produ??o de energia el?trica, tais como hidrel?tricas, termoel?tricas e suas varia??es de combust?veis, usina de ondas, usinas solares e usinas e?licas, de modo que o tema geral Produ??o de Energia El?trica foi dividido em tr?s subtemas: Usinas Hidrel?tricas, Outros Modos de Produ??o de Energia e Usinas Nucleares. O objetivo desta abordagem, al?m de ensinar conceitos f?sicos que envolvem os processos de produ??o de energia el?trica, ?, tamb?m, conscientizar os alunos dos riscos, consequ?ncias e benef?cios de cada modo de produ??o, lev?-los a refletir e avaliar quais os modos mais vantajosos, para que estejam aptos a opinar e participar ativamente de processos decis?rios envolvendo tais quest?es. O produto final deste trabalho ? uma sequ?ncia did?tica com m?todos e recursos did?ticos variados, para servir como guia para outros professores que desejem adotar a proposta. O texto apresenta um breve hist?rico do ensino de ci?ncias no Brasil, suas peculiaridades e necessidades que justificam a proposta e apresenta tamb?m o movimento CTS e suas principais caracter?sticas, que norteiam este trabalho. A metodologia adotada foi a pesquisa-a??o, o que permitiu a readequa??o da proposta ao longo de sua aplica??o. Os resultados foram muito promissores e mostraram que o ensino de f?sica com enfoque CTS, praticado atrav?s de uma abordagem tem?tica voltada para a realidade dos alunos, pode ser um meio de promover uma educa??o cient?fica de qualidade e formar cidad?os aptos a compreender o mundo e a sociedade em que vivem.

Dans le contexte du stockage profond des déchets radioactifs, il est important d'identifier l’hystérésis de saturation de la roche hôte, l'argilite du Callovo-Oxfordien, et sa capacité de scellement (en particulier, la porosité et la distribution de taille des pores). Tout d'abord, six cycles différents d'humidité relative sont destinés à évaluer l’hystérésis de saturation, qui n'est pas observée dans les cycles de faible amplitude. D'autre part, une nouvelle méthode est proposée pour la mesure de la porosité, qui utilise l'injection d'un gaz pour évaluer le volume des pores. Par rapport à la porosité par adsorption d'eau, l’injection de gaz fournit des porosités supérieures d’environ 5%. L'injection de gaz est également utilisée pour quantifier les isothermes de sorption-désorption, qui sont sensiblement différentes de celles obtenues par la méthode gravimétrique, avec un volume poreux accessible au gaz plus élevé pour une humidité relative <43%. Enfin, par Microscopie Electronique à Balayage couplée à un Faisceau Ionique Focalisé (FIB/MEB), on reconstruit le réseau poreux 3D de l'argilite à partir de séries d'images 2D espacées de 10nm : la porosité et la distribution de taille des pores sont quantifiés jusqu’à 20nm, ainsi que l’orientation et l'anisotropie. Avec une résolution plus élevée (jusqu’à moins de 1nm), la Microscopie Electronique à Transmission (MET) montre une grande quantité de pores de l’ordre de quelques nm, situés entre les agrégats d'argile
In the context of deep underground storage of radioactive nuclear waste, it is important to identify the saturation hysteresis of the host rock, i.e. of Callovo-Oxfordian (COx) claystone, and its porosity and pore size distribution. Firstly, six different cycles of relative humidity are applied for saturation hysteresis, which is not observed in the cycles with low magnitude. Secondly, a new method is proposed for measuring porosity, which uses injection of gas to evaluate the pore volume. In contrast to porosity given by water adsorption, the gas injection method provides larger porosity values of around 5%. The gas injection method is also used to quantify the sorption-desorption isotherms of COx claystone, which are significantly different from those obtained by the gravimetric method, with a bigger pore volume accessible to gas in relative humidities < 43%. Finally, by Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM), we obtain 2D image stacks and 3D reconstructed pore volumes, by which porosity and pore size distribution are quantified down to 20nm, as well as pore orientation and anisotropy. At a higher resolution (below 1nm), Transmission Electron Microscopy (TEM) imaging reveals significant amounts of smaller pores (of a few nm) between clay aggregates

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Conselho Nacional de Pesquisa e Desenvolvimento Cient?fico e Tecnol?gico - CNPq
This study is based on the premise that a school?s physical space is constructed socially, asi-de from having the constitution of a dynamic place in constant transformation for teaching and learning, and in thus, takes on a dimension that symbolizes the meanings that it produ-ces. We identified agents of action in the school environment, these being students as well as teachers and other staff members. Therefore, the objective of this study is to investigate the relations produced in the school environment by high school students and teachers, as well as how the ripple effects of these relations play out in the school?s physical and social space. Our hypothesis is : that in comparison with the initial years of basic education, the last years lack investment in the diversity of materials for student learning. The physical space, being one of these possible materials, when it?s not mediated by teaching, becomes the stage for different attitudes about the school. When ideas and perspectives about the school don?t find room for dialogue, this relation can emerge in the care/neglect of the space, while at the same time interfering with development and coexistence among students and teachers. To conduct this research, we developed intervention research utilizing Cultural-Historical Psychology as a theoretical and methodological basis.We conducted this research with high school students and teachers attending night school, at a public school in a city of the state of S?o Paulo). Bi-weekly meetings were held with students, in which main activities inclu-ded the interpretation of images and the creation of artistic works such as drawings, pain-tings, and graffiti, fostering discussion about the meanings that they attribute to the school environment, aiming to transform the space. The research results show the prevalent use of physical and psychological tools as instruments of control, articulated by teachers and ad-ministrators. Regarding the students, we see graffiti as a psychological instrument that aims to transgress the rules imposed on them. We also identified the characteristics of mediations that predominate in the school, such as pragmatic order in contrast with the aesthetic expe-rience, which can foster dialogue about different ways of bringing meaning to the school environment and the pedagogical activities. Lastly, we recognize the important role played by participants when they develop their imaginations in the articulation of diverse positions and experiences, which allow for the conciliation of different meanings that inhabit the very same place.
Este estudo assume o pressuposto de que o espa?o f?sico da escola ? constru?do, al?m de se constituir como lugar din?mico em constante transforma??o para o ensino e a aprendi-zagem, assume-se, assim, uma dimens?o simb?lica pelas significa??es que produz. Identi-ficamos como agentes das a??es sobre o espa?o escolar tanto alunos quanto professores e demais funcion?rios. Assim, o objetivo desta pesquisa ? investigar as rela??es produzidas no ambiente escolar por alunos e professores do Ensino M?dio, bem como essas rela??es repercutem no espa?o f?sico e social da escola. Tem-se por hip?tese que, em compara??o com as s?ries iniciais da educa??o b?sica, as s?ries finais carecem de investimento na di-versidade de materiais para a aprendizagem do aluno. O espa?o f?sico, sendo uma dessas poss?veis materialidades, quando n?o mediado para o ensino, passa a ser palco para diferen-tes posicionamentos frente ? escola. Quando ideias e perspectivas a respeito da escola n?o encontram di?logo, esta rela??o pode transparecer no cuidado/descuidado com o espa?o ao mesmo tempo em que interfere no desenvolvimento e na conviv?ncia tanto de alunos quanto de professores. Para a realiza??o deste estudo, desenvolvemos uma pesquisa-interven??o com estudantes e professores do 1? ano do Ensino M?dio do per?odo noturno, de uma escola estadual do interior de S?o Paulo, utilizando-se como aporte te?rico-metodol?gico a Psi-cologia Hist?rico-Cultural. Foram realizados encontros quinzenais com os alunos em que se teve como atividades principais a leitura de imagens e a produ??o de natureza art?stica, como desenhos, pinturas, grafites, dentre outros de modo a favorecer a discuss?o a respeito dos sentidos que atribuem ao espa?o escolar, visando sua transforma??o. Como resultado da pesquisa, constatamos o uso predominante de instrumentos f?sicos e psicol?gicos como parte do controle feito por parte dos professores e pela gest?o e, por parte dos alunos, perce-bemos a picha??o como instrumento psicol?gico que visa a transgress?o de regras impostas. Identificamos tamb?m a qualidade das media??es que predominam na escola como a de ordem pragm?tica em contraposi??o com a experi?ncia est?tica, que pode favorecer o di?lo-go de diferentes maneiras de significar o espa?o escolar e a atividade pedag?gica. Por fim, reconhecemos o importante papel desenvolvido pela imagina??o na articula??o de posicio-namentos e experi?ncias diversas, o que possibilita a concilia??o de significa??es diferentes a respeito de um mesmo lugar.

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Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
The North Para?ba River Estuary, located in the eastern portion of the Para?ba State, Northeast Brazil, on coordinates 34?50 00 -34?57 30 S and 6?55 00 -7?7 30 W, constitutes a fluvio-marine plain formed by the North Para?ba River and its tributaries Sanhau?, Paroeira, Mandacaru, Tiriri, Tambi?, Ribeira and Guia. This estuary comprises an area of about 260 km2. Increasing human demands on the estuary area and inadequate environment managing have generated conflicts. The present work main purpose is to evaluate the geodynamic evolution of the North Para?ba River Estuary in the period from 1969 to 2001, using digital image processing techniques, thematic digital cartography and multitemporal data integration, combined to geological-geophysical field surveys. The SUDENE cartographic database, converted to digital format were, used to obtain occupation and topographic maps from 1969 and to generate a Digital Elevation Model (DEM). Digital Landsat 7 ETM+ and Spot HRVIR-PAN satellite images interpretation allowed the environmental characterization of the estuary. The most important digital processing results were achieved color composites RGB 5-4-3, 5-3-1, 5-2-NDWI and band ratio 7/4-5/3-4/2, 5/7-3/1-5/4). In addition the fusion image technique RGBI was used by the inclusion of the Spot HRVRI and Landsat 7 ETM+ panchromatic band on I layer with RGB triplets 5-4-3, 5-3-1 and 5/7-3/1-5/4. The DEM and digital images integration allowed the identification of seven geomorphological units: coastal tableland, flowing tray, tide plain, fluvial terrace, submerged dune, beach plain and beach). Both Side Scan Sonar and Echosound were used to analyse underwater surface and bedforms of the estuarine channel, sand predominance (fine to very fine) and 2D dune features 5 m wide and 0.5 m height. This investigation characterized the estuary as an environment dominated by regimen of average flow. The channel depth varies between 1 m and 11 m, being this last quota reached in the area of Porto de Cabedelo. The chanel estuary is relatively shallow, with erosion evidences mainly on its superior portion, attested by sand banks exposed during the low tide. Multitemporal digital maps from 1969 and 2001 integration were obtained through geoprocessing techniques, resulting the geodynamic evolution of the estuary based on landuse, DEM geomorphology and bathymetric maps
O Estu?rio do Rio Para?ba do Norte, localizado na por??o oriental do Estado da Para?ba, Nordeste do Brasil, entre as coordenadas 34?50 00 S a 34?57 30 S e 6?55 00 W e 7?7 30 W, constitui uma plan?cie fl?vio-marinha formada pelo rio Para?ba do Norte e seus afluentes Sanhau?, Paroeira, Mandacaru, Tiriri, Tambi?, Ribeira e Guia, envolvendo uma ?rea de aproximadamente 260 Km2. A crescente press?o populacional sobre o estu?rio vem gerando conflitos e um manejo inadequado deste ambiente. O presente trabalho teve como objetivo principal avaliar a evolu??o geodin?mica do Estu?rio do Rio Para?ba do Norte, no per?odo de 1969 a 2001, por meio do processamento digital de imagens de sensoriamento remoto, da cartografia tem?tica digital e da integra??o de dados georreferenciados multitemporais, combinados a uma base geol?gica-geof?sica obtida em levantamentos de campo. A partir das cartas da SUDENE foram obtidos os mapas digitais de uso e ocupa??o do solo de 1969 e o topogr?fico, sendo este ?ltimo utilizado na gera??o do MDT. O processamento digital das imagens dos sat?lites Landsat 7 ETM+ e Spot HRVIR-PAN possibilitou a gera??o de produtos imagens utilizados como base na identifica??o e caracteriza??o geoambiental do estu?rio no per?odo atual (composi??es coloridas das bandas 5-4-3, 5-3-1, 5-2-NDWI e das raz?es das bandas 7/4-5/3-4/2, 5/7-3/1-5/4 combinadas em RGB). A t?cnica de fus?o de imagens RGBI foi utilizada com a inclus?o da banda pancrom?tica do Spot HRVIR e do Landsat 7 ETM+ na camada I nos trios de bandas em RGB 5-4-3, 5-3-1 e 5/7-3/1-5/4. A integra??o do MDT com as imagens digitais possibilitou a identifica??o de sete unidades geomorf?logicas no estu?rio (tabuleiro costeiro, vertente, plan?cie de mar?, terra?o fluvial, dunas subaquosas, plan?cie praial e praia). O Sonar de Varredura Lateral (Side Scan Sonar) e o Ecobat?metro, associados ?s coletas de sedimentos de fundo forneceram informa??es sobre as condi??es atuais da superf?cie de fundo do canal estuarino, revelando o predom?nio de areias (areia fina a muito fina) e fei??es dunares 2D com largura de 5m e altura de 0.5 m, em m?dia, caracterizando o estu?rio como um ambiente dominado por regime de fluxo m?dio. A profundidade varia de 1 m a 11 m, sendo esta ?ltima cota alcan?ada nas proximidades do Porto de Cabedelo. De maneira geral o estu?rio ? relativamente raso, com evid?ncias de assoreamento principalmente na sua por??o superior, comprovado pela presen?a de dunas subaquosas expostas durante a mar? baixa. Por meio de t?cnicas de Geoprocessamento foi poss?vel integrar os dados de 1969 com os de 2001, resultando na gera??o dos mapas digitais multitemporais uso e ocupa??o do solo, MDT, gemorfol?gico e batim?trico, representativos da evolu??o geodin?mica do estu?rio

Il lavoro tratta l’applicazione di un progetto di Certificazione del Sistema di Gestione della Qualità di un’innovativa linea di Business nel settore delle macchine per il confezionamento delle bevande. Questo lavoro è stato preparato durante un periodo di Stage della durata di sei mesi effettuato presso SACMI IMOLA S.C. (Imola, BOLOGNA) a seguito della necessità, riscontrata dal management, di allineare il sistema gestione qualità della nuova linea di business alla normativa ISO 9001:2008, come per le altre linee di business dell’azienda. Tutto questo mediante l’implementazione di un sistema di Business Process Management (BPM) e di tutti i sistemi informatici ad esso collegati. La tesi si struttura in tre parti. Nella prima parte, attraverso un’indagine della letteratura di riferimento, si sono indagati l’evoluzione storica, la struttura attuale e i possibili scenari evolutivi inerenti il concetto di qualità, il sistema gestione qualità e la normativa di riferimento. La seconda parte è dedicata all’approfondimento delle tematiche del BPM, i cui principi hanno guidato l’intervento effettuato. La ricerca è stata condotta allo scopo di evidenziare le radici e gli elementi innovativi che contraddistinguono questo approccio di “management”, descrivere gli aspetti che ne hanno determinato la diffusione e l’evoluzione ed evidenziare, inoltre, il collegamento tra l’approccio per processi che sta alla base di questa filosofia di management e lo stesso approccio previsto nella normativa ISO 9001:2008 e, più specificatamente nella cosiddetta Vision 2000. Tale sezione si conclude con la formalizzazione delle metodologia e degli strumenti effettivamente utilizzati per la gestione del progetto. La terza ed ultima parte del lavoro consiste nella descrizione del caso. Vengono presentate le varie fasi dell’implementazione del progetto, dall’analisi dell’attuale situazione alla costruzione dell’infrastruttura informatica per l’attuazione del BPM ottenuta attraverso l’applicazione dei “criteri di progettazione” trattati dalla letteratura di riferimento, passando per la mappatura dei processi attualmente in vigore e per l’analisi delle performance del processo attuale, misurate attraverso indicatori sviluppati “ad hoc”. Il lavoro è arricchito dall’analisi di un’innovativa metodologia per la creazione di un sistema di gestione integrato delle certificazioni (ISO 9001, ISO 14001, OHSAS 18001) fondato sull’infrastruttura informatica creata.

Cette thèse vise à développer des méthodologies originales et appropriées pour modéliser la propagation des ondes EM dans des tunnels de forme quelconque et à proposer des méthodologies pour optimiser les spécifications, la conception et le positionnement des antennes en tunnel. Nous avons proposé une méthode originale d’analyse modale full-wave pour traiter le cas de la propagation des ondes EM dans des structures de grandes dimensions électriques ou en milieux confinés de forme quelconque tels que les tunnels. Cette méthode consiste en une approche modale qui s’appuie sur l’algorithme 2,5D TLM et l’algorithme Matrix Pencil pour la discrimination des modes dans des structures à pertes dans lesquelles la densité modale est élevée et les modes se superposent. Nous avons considéré de nouvelles conditions aux limites appelées SIBC (Surface Impedance Boundary Condition) pour les guides d’ondes diélectriques à pertes. Afin de pouvoir analyser les cas généraux et plusieurs configurations de tunnel réalistes, nous avons proposé une nouvelle nomenclature des modes. En effet, la nomenclature des modes existante n’est plus applicable en raison des effets de dépolarisation des modes dans certains cas réalistes. Une nouvelle méthodologie pour la détermination des spécifications et des positions des antennes en milieux confinés ou guidés a ensuite été développée. Cette méthodologie repose sur la combinaison d’une analyse modale et de techniques d’optimisation afin d’ajuster le poids des différents modes dans le tunnel. Cette approche est utilisée dans le cas des antennes adaptatives mais elle n’a jamais été appliquée au cas de la propagation multi modes en tunnel
This thesis aims to develop original and appropriate methodologies to model the propagation of EM waves in tunnels of any shape and to propose methodologies to optimize the specification, design and positioning of the antenna in the tunnel. We proposed a novel method for full-wave modal analysis to treat the case of EM wave propagation in structures of large electric dimensions or confined environments of any shape such as tunnels. This method is a modal approach which is based on the 2.5D TLM algorithm and Matrix Pencil algorithm for the discrimination of modes in lossy structures in which the modal density is high and the modes overlap. We considered new boundary conditions called SIBC (Surface Impedance Boundary Condition) for dielectric waveguides with losses. To analyze the general case and several realistic tunnel configurations, we proposed a new classification of modes. Indeed, the classification of existing methods is no longer applicable due to depolarization effects in some realistic cases. A new methodology for determining the specifications and positions of antennas in confined or guided structures was then developed. This methodology is based on a combination of modal analysis and optimization techniques to adjust the weights of the different modes in the tunnel. This approach is used in the case of adaptive antennas, but it has never been applied to the case of multipath propagation modes in the tunnel

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Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES
The object of study and analysis of this research are the articles published in the Thematic Working Group Inclusion and Difference proceedings Inclusion and Difference of the Brazilian Congress of Sports Sciences, between 2003 and 2013. The general objective is to identify the epistemological bases present in the production of knowledge in Physical Education, from the annals of the mentioned Thematic Working Group, and how these bases respond to the issue of inclusion of students with disabilities. For this purpose, we present how to constitute the relationship between the characterization of the research, the main issues addressed and the inclusion perspectives found in each approach. Using an analytical tool in consonance with the paradigmatic matrix, that points out the technical, methodological, theoretical and epistemological levels. This methodological procedure made it possible to realize, in the 31 articles analyzed, that 90% used the Phenomenological-Hermeneutic approach and 10% used the Critical-Dialectic approach, and has not identified any article used the Empirical-Analytical approach. We found that each level of the instrument used for analysis of the articles made evident the predominance of the approach taken, in other words, in the articles in which the Phenomenological-Hermeneutic approach was predominant, it was observed that the discussion is focused on understanding the phenomena and where these have as a base. In the articles using the Critical-Dialectic approach we note that the discussion was taking as a basis the issues of social context and its alternative processing. Given the limitations found in this research, both personal and time to deepen some debate, it is necessary that further research be done in order to expand and advance the contributions in the knowledge production of physical education, and exclusion / inclusion, pointing out the various conflicts that implies in this context.
Esta pesquisa tem como fonte de estudo e an?lise os artigos publicados nos anais do Grupo de Trabalho Tem?tico Inclus?o e Diferen?a do Congresso Brasileiro de Ci?ncias do Esporte (CONBRACE), entre os anos de 2003 e 2013. O objetivo geral ? identificar as bases epistemol?gicas presentes na produ??o do conhecimento em Educa??o F?sica, a partir dos anais do citado Grupo de Trabalho Tem?tico (GTT), e como estas bases respondem ? quest?o da inclus?o de alunos com defici?ncia. Com este intuito, apresentamos como se instituem as rela??es entre a caracteriza??o da pesquisa, as principais tem?ticas abordadas e as perspectivas de inclus?o em cada abordagem encontrada. Utilizando um instrumento de an?lise em conson?ncia com a matriz paradigm?tica, que aponta os n?veis t?cnico, metodol?gico, te?rico e epistemol?gico. Este procedimento metodol?gico possibilitou perceber nos 31 artigos analisados, que 90% utilizaram a abordagem Fenomenol?gica-Hermen?utica e 10% a abordagem Cr?tico-Dial?tica, sendo que n?o foi identificado nenhum artigo que utilizou a abordagem Emp?rico-Anal?tica. Verificamos que cada n?vel do instrumento utilizado para an?lise dos artigos deixou evidenciada a predomin?ncia da abordagem adotada, ou seja, nos artigos em que a abordagem Fenomenol?gica-Hermen?utica foi predominante, foi poss?vel observar que a discuss?o ? centrada na compreens?o dos fen?menos e onde estes t?m como base. Nos artigos em que utilizaram a abordagem Cr?tico-Dial?tica, constatamos que a discuss?o tomava como base as quest?es do contexto social e as alternativas de transforma??o deste. Diante das limita??es encontradas nesta pesquisa, tanto pessoais quanto de tempo para aprofundar alguns debates, se faz necess?rio que outras pesquisas sejam feitas na perspectiva de ampliar e avan?ar nas contribui??es da produ??o do conhecimento da Educa??o F?sica, da exclus?o/inclus?o apontando os diversos conflitos que implicam neste contexto.

This thesis deals with a field of information modeling and its relation to systems architecture. It is divided into two notional parts -- theoretical (first and second chapter) and practical (third and fourth chapter). First chapter explains the meaning of the term 'information model', compares it to the term 'data model' and then introduce its practical use in an enterprise modeling. It also defines the term of 'systems architecture' in its broad meaning and reduces it to three narrow meaning -- enterprise architecture, information architecture and information systems architecture, while it explains their relation to the information modeling. Finally this chapter provides the base for information model implementation methodology created later in the practical part of this thesis. Second chapter introduces architecture framework called TM Forum Frameworx specialized for a telecommunication services provider. It consists of three standards for business process, information and application architecture. The second one defines specific information model which is described partly in the second chapter and partly in the appendix B of this thesis. Third chapter describes the first of two contributions of this thesis - the information model implementation methodology. This methodology is applicable to any implementation of an information model. Three sections of this chapter contains diagrams and description of three phases of the methodology - pre-implementation phase, implementation phase and post-implementation phase. In the end of the chapter there is a table containing outputs of every single activity performed during all the phases. Fourth and last chapter then describes and evaluates real implementation of the information model from TM Forum Frameworx in the systems architecture department of an enterprise providing telecommunication services. This implementation based on the created methodology and its successful results then became the second contribution of this thesis.

Nitric oxide (NO) is an important biological molecule within the body, which over production of this molecule in response to different stimulations can cause various inflammatory diseases. Over production of this molecule is caused by the induction of the inducible nitric oxide synthase (iNOS) enzyme. This enzyme uses L-arginine as a substrate and therefore the presence and transport of this amino acid into the cells can be a key factor in regulating NO over production. Different signalling mechanisms have been implicated in the regulation of this pathway and one of which involves the Mitogen Activated Protein Kinases (MAPK). This family of proteins respond to inflammatory conditions and may mediate effects induced by inflammatory mediators. Of the MAPKs, the role of the c-Jun-N-terminal kinase (JNK) pathway in the induction of iNOS is still controversial. JNK and its downstream target, the transcription factor Activator Protein-1 (AP-1), have shown contradictory effects on iNOS induction leading to controversies over their role in regulating iNOS expression in different cell systems or with various stimuli. The studies described in this thesis have determined the role of JNK/AP-1 on iNOS expression, NO production, L-arginine uptake and also on the transporters responsible for L-arginine transport into the cells. The studies were carried out in two different cell types: rat aortic smooth muscle cells (RASMCs) and J774 macrophages which are both critically associated with the over production of NO in vascular inflammatory disease states. The first approach was to block the expression of the inducible L-arginine-NO pathway using SP600125 and JNK Inhibitor VIII which are both pharmacological inhibitors of JNK. The results from these studies showed that the pharmacological intervention was without effect in RASMCs, but inhibited iNOS, NO and L-arginine transport in J774 macrophages. In contrast, the molecular approach employed using two dominant negative constructs of AP-1 (TAM-67 and a-Fos) revealed a different profile of effects in RASMCs, where a-Fos caused an induction in iNOS and NO while TAM-67 had an inhibitory effect on iNOS, NO, L-arginine transport and CAT-2B mRNA expression. The latter was unaffected in RASMCs but suppressed in J774 macrophages by SP600125. Examination of JNK isoforms expression showed the presence of JNK1 and 2 in both cell systems. Moreover, stimulation with LPS/IFN- or LPS alone resulted in JNK phosphorylation which did not reveal any difference between smooth muscle cells and macrophages. In contrast, expression and activation of AP-1 subunits revealed differences between the two cell systems. Activation of cells with LPS and IFN- (RASMCs) or LPS alone (J774 macrophages) resulted in changes in the activated status of the different AP-1 subunit which was different for the two cell systems. In both cell types c-Jun, JunD and Fra-1 were increased and in macrophages, FosB activity was also enhanced. Inhibition of JNK with SP600125 caused down-regulation in c-Jun in both cell types. Interestingly this down-regulation was in parallel with increases in the subunits JunB, JunD, c-Fos and Fra-1 in RASMCs or JunB and Fra-1 in J774 macrophages. Since, SP600125 was able to exert inhibitory effects in the latter cell type but not in RASMCs, it is possible that the compensatory up-regulation of certain AP-1 subunits in the smooth muscle cells may compensate for c-Jun inhibition thereby preventing suppression of iNOS expression. This notion clearly needs to be confirmed but it is potentially likely that hetero-dimers formed between JunB, JunD, c-Fos and Fra-1 could sustain gene transcription in the absence of c-Jun. The precise dimer required has not been addressed but unlikely to exclusively involve JunB and Fra-1 as these are up-regulated in macrophages but did not sustain iNOS, NO or induced L-arginine transport in the presence of SP600125. To further support the argument above, the dominant negatives caused varied effects on the activation of the different subunits. a-Fos down-regulated c-Jun, c-Fos, FosB, Fra-1 whereas TAM-67 reduced c-Jun and c-Fos but marginally induced Fra-1 activity. Associated with these changes was an up-regulation of iNOS-NO by a-Fos and inhibition by TAM-67. Taken together, the data proposes a complex mechanism(s) that regulate the expression of the inducible L-arginine-NO pathway in different cell systems and the complexity may reflect diverse intracellular changes that may be different in each cell type and not always be apparent using one experimental approach especially where this is pharmacological. Moreover, these findings strongly suggest exercising caution when interpreting pure pharmacological findings in cell-based systems particularly where these are inconsistent or contradictory.

The majority of UK’s intermediate level radioactive waste is currently stored in 316L and 304L austenitic stainless steel containers in interim storage facilities for permanent disposal until a geological disposal facility has become available. The structural integrity of stainless steel canisters is required to persevere against environmental degradation for up to 500 years to assure a safe storage and disposal scheme. Hitherto existing severe localised corrosion observances on real waste storage containers after 10 years of exposure to an ambient atmosphere in an in-land warehouse in Culham at Oxfordshire, however, questioned the likelihood occurrence of stress corrosion cracking that may harm the canister’s functionality during long-term storage. The more corrosion resistant duplex stainless steel grade 2205, therefore, has been started to be manufactured as a replacement for the austenitic grades. Over decades, the threshold stress corrosion cracking temperature of austenitic stainless steels has been believed to be 50-60°C, but lab- and field-based research has shown that 304L and 316L may suffer from atmospheric stress corrosion cracking at ambient temperatures. Such an issue has not been reported to occur for the 2205 duplex steel, and its atmospheric stress corrosion cracking behaviour at low temperatures (40-50°C) has been sparsely studied which requires detailed investigations in this respect. Low temperature atmospheric stress corrosion cracking investigations on 2205 duplex stainless steel formed the framework of this PhD thesis with respect to the waste storage context. Long-term surface magnesium chloride deposition exposures at 50°C and 30% relative humidity for up to 15 months exhibited the occurrence of stress corrosion cracks, showing stress corrosion susceptibility of 2205 duplex stainless steel at 50°C.The amount of cold work increased the cracking susceptibility, with bending deformation being the most critical type of deformation mode among tensile and rolling type of cold work. The orientation of the microstructure deformation direction, i.e. whether the deformation occurred in transverse or rolling direction, played vital role in corrosion and cracking behaviour, as such that bending in transverse direction showed almost 3-times larger corrosion and stress corrosion cracking propensity. Welding simulation treatments by ageing processes at 750°C and 475°C exhibited substantial influences on the corrosion properties. It was shown that sensitisation ageing at 750°C can render the material enhanced susceptible to stress corrosion cracking at even low chloride deposition densities of ≤145 µm/cm². However, it could be shown that short-term heat treatments at 475°C can decrease corrosion and stress corrosion cracking susceptibility which may be used to improve the materials performance. Mechanistic understanding of stress corrosion cracking phenomena in light of a comprehensive microstructure characterisation was the main focus of this thesis.

碩士
國立清華大學
核子工程與科學研究所
101
Silicon carbides (SiC) are considered as one of the promising candidates for structural and core materials used in fusion reactor and high temperature gas-cooled reactor (HTGR) due to its high thermal stability, and good resistance to irradiation and chemical attack. Single crystal 3C-SiC with less intrinsic defects was used to precisely characterize the radiation-induced defects in 3C-SiC. In addition, there are limited discussions related to radiation effect of SA-Tyrannohex fiber-bonded composite at high temperatures. Therefore, in this study, single crystal 3C-SiC thin film and SA-Tyrannohex SiC fiber-bonded composite were irradiated at 1000℃ to 1350℃ with 7MeV Si3+ ion to simulate the neutron irradiation in reactors. The microstructure of the irradiated SiC was examined by using high resolution transmission electron microscope (HRTEM) and spherical aberration corrected scanning TEM (Cs-corrected STEM). In irradiated single crystal 3C-SiC, high resolution images showed that the planar defects were extrinsic stacking faulted loop with changing atomic sequences and intrinsic stacking faulted loop, i.e. vacancy loop. The atomic configurations were confirmed by STEM annular bright field image. However, no void has been found in single crystal 3C-SiC due to formation of vacancy loops, vacancies releasing from surface, or too small to be visible (<1 nm). In addition, dislocation loops, voids, and edge dislocations in SA-Tyrannohex SiC fiber-bonded composite after irradiation were investigated. This SiC composite are able to suppress void growth and lower the void density after high-temperature irradiation due to its small grain size (~300 nm). Besides, larger voids (with diameter 10-40 nm) formed in alumina with preferred orientation after irradiation perhaps resulting in degradation of strength of the SA-Tyrannohex SiC fiber-bonded composite.

In the first part of the thesis, an extensive discussion on the research activity concerning the extended bidimensional defects within the 3C-SiC will be exposed. These defects are, in fact, one of the main causes that hinders the use of 3C-SiC heteroepitaxies grown on Si substrates. TEM investigations together with molecular dynamics simulations have been used to trace the structure of the main two-dimensional defects affecting the heteroepitaxial layers in 3C-SiC, with particular reference to Inverted Domain Boundaries (IDBs) and Stacking Faults (SFs). In this work Domain boundaries (DBs) generated during the growth of 3C-SiC on (001) Si and their interaction with stacking faults (SFs) will be studied. Direct Scanning Transmission Electron Microscopy (STEM) images will exhibit that DBs are inverted domain boundaries otherwise called antiphase boundary (IDBs or APB). The atomic arrangement of this IDB is different from the expected boundaries described in the literature, nevertheless, it has a highly coherent nature. The IDBs propagate in a complex way through the crystal. A close relationship will be identified between the IDBs lying on the (111) plane and the SFs, which appear to be coupled. Furthermore, it will be observed that the Partial dislocations surrounding the SFs possess an unconventional lying plane, i.e. [112], [123], [134]. Molecular dynamics simulations demonstrate the stability of the directions [110] as well as [112] direction, while the directions [123] and [134] of the partial dislocations (PDs) evolve towards [112] and [110]. The unusual directions will be identified by experimental investigation as they obey to rules of minimization of the strain energy, in partial dislocations. A structural characterization and distribution of SFs was performed by μ-Raman spectroscopy and room-temperature μ-photoluminescence. Two kinds of SFs, 4H-like and 6H-like, will be identified near the substrate interface. Each kind of SFs shows a characteristic photoluminescence emission of the 4H-SiC and 6H-SiC located at 393 and 425 nm, respectively. 4H-like and 6H-like SFs show different distribution along film thickness. The reported results were discussed in relation with the experimental data and theoretical models present in the literature. Investigations related to the temperature influence on the homo-epitaxial growth process of 3C-SiC will be presented. Different morphological analyses indicate that the growth temperature and the growth rate play a fundamental role in the stacking faults density. In details, X-ray diffraction and micro-Raman analysis show the strict relationship between growth temperature, crystal quality, and doping incorporation in the homo-epitaxial chemical vapor deposition CVD growth process of a 3C-SiC wafer. Furthermore, photoluminescence spectra show a considerable reduction of point defects during homo-epitaxy at high temperatures. Furthermore, properties of cubic silicon carbide (3C-SiC) grown epitaxially on a patterned silicon substrate composed by squared inverted silicon pyramids (ISP) will be shown. This compliant substrate prevents the stacking faults, usually found at the SiC/Si interface, to reach the surface. We investigated the effect of the size of the inverted pyramid on the epilayer quality. We noted that anti-phase boundaries (APBs) develop between adjacent faces of the pyramid and that the SiC/Si interfaces have the same polarity on both pyramid faces. Structure of the heterointerface will be investigated. Moreover, due to the merging of APB in the vertex of the pyramid, voids buried on the epilayer form. We will demonstrate that careful control of the growth parameters allows to modify the height of the void and the density of APBs, improving SiC epitaxy quality. It will be discussed the use of a buffer layer between the epitaxial layer and the substrate in order to reduce the defectiveness and improve the overall quality of the SiC epi-film. In particular, we find that the morphology and the quality of the epi-film depends on the carbonization temperature and the concentration of Ge in close proximity of the Si1-xGex/SiC interface. Ge segregation at the interface influences the film quality, and in particular a [Ge]>12% in close proximity to the interface leads to the formation of poly-crystals, while close to 10% induces a mirror like morphology. Moreover, by finely tuning the Ge concentration and carbonization temperature, crystal quality higher than that observed for SiC grown on bare silicon will be achieved. In chapter 3 we will study the crystal defectiveness subsequent to ion implantation and annealing by using various techniques including photoluminescence (PL), Raman spectroscopy and transmission electron microscopy (TEM). The aim of this work is to test the effectiveness of double step annealing to reduce the density of point defects generated during the annealing of a P implanted 4HSiC epitaxial layer. The outcome evidences that neither the first 1 hour isochronal annealing at 1650 - 1700 - 1750 °C, nor the second one at 1500 °C for times between 4 hour and 14 hour are able to recover a satisfactory crystallinity of the sample. Prismatic interstitial-type dislocation loops have been found as the dominant extended defect. Their average size are typically 1–20 nm in diameter and reside on the {0001} and {11-20} plane, consistent with Frank type dislocation behavior. Conventional annealing do not allow lattice relaxation towards low energy configurations. Anisotropic-next-nearest-neighbor Ising model demonstrated that evolution towards prismatic dislocation loops is highly energetic. Indeed, Raman E2(TO) mode displayed large in plane stress values up to 172 Mpa. This work will also describes the development of a new method for ion implantation induced crystal damage recovery using multiple XeCl (308 nm) laser pulses with a duration of 30 ns. Experimental activity was carried on single phosphorus (P) as well as double phosphorus and aluminum (Al) implanted 4H-SiC epitaxial layers. Samples will be characterized through μ-Raman spectroscopy, Photoluminescence (PL) and Transmission Electron Microscopy (TEM) and results were compared with those coming from P implanted thermally annealed samples at 1650–1700–1750 °C for 1 h as well as P and Al implanted samples annealed at 1650 °C for 30 min. The activity outcome shows that laser annealing allows to achieve full crystal recovery in the energy density range between 0.50 and 0.60 J/cm2. Moreover, laser treated crystal exhibits an almost stress-free lattice with respect to thermally annealed samples that are characterized by high point and extended defects concentration. Implanted area was almost preserved, except for some surface oxidation processes due to oxygen leakage inside the testing chamber. To work around surface erosion phenomena it will be proposed the practicability of coating systems designed to minimize the surface degradation of SiC following laser annealing process. This strategy based on a graphitic coating plays a key role along the annealing in a thermal nonequilibrium regime to obtain a high dopant activation. Thanks to its 3800 °C melting temperature and high absorption coefficient, graphite is, in fact, the best candidate to fully absorb laser radiation, allowing a heat diffusive regime along the underlying layers. Characterization will be performed by means of μ-Raman accurate analysis which allows to highlight the high crystalline quality and the absence of stress phenomena inside the crystal. A detailed portrait of the damage thresholds will be reported with particular emphasis on the thicknesses used to minimize sample erosion and, at the same time, ensure high activation of the implanted dopant. Circular Transfer Length Method (CTLM) measurements tests were carried out and will prove remarkable P activation on irradiated site. The 90 nm graphite coated sample will reveal at 0.5 J/cm2 activation values equal to 6.59·1019 ±1.95 e/cm3 which correspond to approximately 66% of P implanted activation. This is slightly higher than the value coming from the thermally annealed sample extracted from literature (around 62%). The results of this experimental activity give way to laser annealing process viability for damage recovery and dopant activation inside the implanted area. Starting from the state of the art about the formation of extended defects in ion implanted 4H-SiC homo-epitaxial wafers following high temperature post-implantation annealing, the improvement of the laser annealing technique is proposed as a turning point of post-implantation thermal processes. The study provided within this work has, therefore, as its main ambition to provide an accurate characterization of defects in SiC films and their behavior as a function of growth as well as in doping processes. The objective therefore concerns the removal of the relevant drawbacks in the development and the viability of reliable and efficient electronics devices.

Thesis (M.S.)--State University of New York at Buffalo, 2006.
Title from PDF title page (viewed on Mar. 15, 2007) Available through UMI ProQuest Digital Dissertations. Thesis adviser: Wobschall, Darold. Includes bibliographical references.

Thesis (M.S.)--State University of New York at Buffalo, 2008.
Title from PDF title page (viewed on Feb. 12, 2009) Available through UMI ProQuest Digital Dissertations. Thesis adviser: Munoz, Carlos A. Includes bibliographical references.

Thèse (M.Sc.)--Université Laval, 1997.
Sur la p. de t., les symboles "TM" pour enregistrer, est mentionné dans le titre à la suite de Heme-Assist, sous-forme d'exposant. Bibliogr.: f. 104-110. Publ. aussi en version électronique.