Thesis (Ph.D.)--University of Wollongong, 2004. / Typescript. Includes bibliographical references.

Thesis (M.Eng.)--University of Wollongong, 2004. / Typescript. Includes bibliographical references: leaf 104-108.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (M.S.)--State University of New York at Binghamton, Department of Physics, Applied Physics and Astronomy, 2009. / Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 126-133).

Thesis (MIng)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Thesis (MScEng)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Very Large Scale Integration (VLSI) of the Rapid Single Flux Quantum (RSFQ) superconducting logic family is researched. Insight into the design methodologies used for large-scale digital systems and related logistics are reviewed. A brief overview of basic RSFQ logic gates with in mind their application in a cell based layout scheme suited for RSFQ is given. A standard cell model is then proposed, incorporating these cells, on which, a library of low temperature superconducting (L TS) cells are laid out. Research is made into computer techniques for storing and manipulating large-scale circuit netlists. On this base, a method of technology mapping Boolean circuits to an RSFQ equivalent is achieved. Placements on-chip are made, optimized for minimum net length, routed and exported to a popular electronic mask format. Finally, the convergent technology fields of solid state cooling and high-temperature superconducting electronics (HTS) are investigated. This leads to a proposal for a low profile, low cost, HTS cryopackaging concept. / AFRIKAANSE OPSOMMING: Grootskaalse integrasie (VLSI) van die "Rapid Single Flux Quantum" (RSFQ) supergeleidende familie van logiese hekke word uiteengesit. Insig in die ontwerpmetodes vir grootskaaIse digitale stelsels en verwante aspekte word ondersoek. 'n Kort oorsig van basiese RSFQ logiese hekke word gegee, met hulle toepassing in 'n uitlegskema wat geskik is vir RSFQ. 'n Standaard sel model, wat bogenoemde selle insluit, word voorgestel en 'n selbiblioteek word uitgele vir lae temperatuur supergeleidende bane. Ondersoek word ingestel na die manipulasie van die beskrywing van elektroniese bane en 'n manier om logiese Boolese baanbeskrywings om te skakel na fisiese RSFQ bane. Die fisiese plasing van selle word bespreek ten einde die verbindingslengte tussen selle te minimeer. Die finale uitleg word omgeskakel na 'n staandaard elektroniese formaat vir baanuitlegte. Die konvergerende tegnologievelde van "soliede toestand" verkoeling en hoe-temperatuur supergeleidende elektroniese bane word bespreek. Ten slotte word 'n nuwe tipe, lae profiel en lae koste kriogeniese verpakking voorgestel.

Made available in DSpace on 2014-06-11T19:23:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-23Bitstream added on 2014-06-13T19:50:09Z : No. of bitstreams: 1 motta_m_me_bauru.pdf: 6420276 bytes, checksum: 433e73718fc23057725e70c7504a674c (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A síntese e as condições de processamento sempre foram temas importantes em Ciências dos Materiais. Com o interesse crescente em componentes miniaturizados, que possuam propriedades especiais, os materiais nanométricos têm se desenvolvido grandemente. Neste trabalho, a otimização do processo de obtenção da cerâmica supercondutora Y'Ba IND. 2''Cu IND. 3''O IND. 7-δ' com estrutura nanoparticulada e a obtenção de elos fracos (weak-links) suficientemente fortes e homogêneos foram estudados. As amostras foram preparadas usando o Método dos Precursores Poliméricos Modificado (MPPM) com variação do agente de quelação (ácido cítrico, ácido tartárico e EDTA) e da atmosfera de tratamento posterior (nitrogênio e oxigênio). O objetivo foi variar as condições de sinterização dos nanopós e produzir que possuíssem partículas com dimensões nanométricas de modo a obter regiões intergranulares com uma distribuição de densidade de corrente crítica estreita e, ao mesmo tempo, não ultrapassar os limites que promovam o crescimento dos grãos. Para estes estudos, foram realizadas caracterizações estruturais e microestruturais através de Espectroscopia no Infravermelho com Transformada de Fourier (FTIR), Difração de Raios X (DRX), Microscopia Eletrônica de Varredura (MEV) e Microscopia Eletrônica de Transmissão (MET), e caracterização magnética por medidas de Magnetização DC e de Susceptibilidade AC. Além dos efeitos provenientes do processamento, estudou-se a inserção de defeitos de forma controlada, substituindo parcialmente o cobre na forma Y'Ba IND. 2''Cu IND. 3''O IND. 7-δ' por M = Zn e Ni, procurando estabelecer a relação entre os defeitos causados pelas substituições (intrínsecos) e as inomogeneidades estruturais devidas ao processamento (extrínsecos) através de mudanças no diagrama de fases da Matéria de Vórtices. / The synthesis and processing conditions to produce materials always were important themes for study in Materials Science. The interest in miniaturized components with special properties like nanostructured materials has been strongly developed in these last years. In this work, the optimization processes to obtain superconducting ceramic Y'Ba IND. 2''Cu IND. 3''O IND. 7-δ' nanoparticles with strong and homogeneous weak-links were studied. The samples were prepared using the Modified Polymeric Precursos Method (MPPM) by the use of different chelating agent (citric acid, tartaric acid and EDTA) and different heat treatment atmosphere (nitrogen and oxygen). Thus, variations in the nanopowder sintering conditions in order to obtain nanometric samples with intergranular region with narrow critical current density distribution without promoting grain growth were also tested. For this, microstructural and structural characterization using Fourier Transform Infrared (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM) were used and magnetic characterization through DC-Magnetization and AC-Susceptibility was also performed. Moreover of the processing effects, it was studied the doping controlled, replacing partially in Y'Ba IND. 2''Cu IND. 3''O IND. 7-δ' by M = Zn e Ni and looking for the relation between effects due substituent (intrinsic) and the structural inhomogeneous due processing (extrinsic) comparing its effects their at vortex matter phase diagram.

abstract: The discovery of the superconductor MgB2 led to the increase of research activity for more compounds adopting the AlB2 structure type and containing superconductive properties. The prominent successor compounds were the silicide systems, AeAlSi (Ae=Sr, Ba, Ca). Presented here is an extension of this investigation to the germanides, SrAlGe and BaAlGe. The ternary structures were synthesized through arc-melting elemental stoichiometric mixtures and structurally characterized by x-ray powder diffraction. Both crystallize as the hexagonal SrPtSb structure type, a variant of the AlB2 structure type. The low temperature region was measured on a Vibrating Sample Magnetometer (VSM) and both present the onset of superconductivity below 7K. These compounds are susceptible to hydrogen absorption and the new polyanionic hydrides, SrAlGeH and BaAlGeH, structural and dynamic properties are presented. The hydrides were synthesized via two distinct methods. One method is the reaction of SrH2 (BaH2) with elemental mixture of the Al and Ge under pressurized hydrogen and the other is a hydrogenation of the SrAlGe and BaAlGe. Both crystallize in the trigonal SrAlSiH structure type, as determined from Rietveld analysis on powder neutron diffraction measurements. The hydrogen is coordinated by both the active metal and aluminum atoms, providing a unique environment for studying metal-hydrogen interactions. When exposed to air, both the hydrides and alloys transform from a crystalline grey to an amorphous yellow powder accompanied by a dramatic volume increase. Infrared spectroscopy shows the disappearance of the bands associated with the Al-H bond and the appearance of Ge-H and O-H bands. This indicates the material reacts with atmospheric water. / Dissertation/Thesis / M.S. Chemistry 2011

Neste trabalho descrevemos a concepção e o desenvolvimento de uma página na Internet sobre o tema da supercondutividade, bem como o uso e avaliação da página como instrumento de ensino em uma turma de terceiro ano do Ensino Médio do Colégio Frederico Jorge Logemann em Horizontina/RS. Para esse desenvolvimento, foram necessários alguns recursos de hipermídia e a página representa o produto educacional da dissertação. A implementação do tema deu-se à luz de epistemologias contemporâneas que problematizam visões ingênuas sobre a natureza da ciência. Para tanto, destacam-se as epistemologias de Popper (1993), Kuhn (1978), Lakatos (1989) e Laudan (1977) devido à sua relevância no ensino de física, com ênfase na principal convergência existente entre essas visões de ciência: a oposição ao empirismo-indutivismo. Como referencial teórico psicológico, utilizamos a psicologia sócio-histórica de Vygotsky para uma maior compreensão do processo ensino-aprendizagem envolvido no presente projeto. Avaliamos a implementação do projeto a partir de instrumentos que tornaram evidentes a aprendizagem significativa dos alunos sobre o tema. A metodologia utilizada durante as aulas, em que o assunto foi abordado, foi basicamente pautada na utilização da página desenvolvida para essa finalidade, bem como na realização de atividades experimentais, por parte dos alunos, para que pudessem visualizar a parte prática envolvida na montagem do experimento e os resultados encontrados. A partir das animações disponíveis no material didático, a idéia foi promover compreensão do fenômeno e suas conseqüências. A página elaborada e fundamentada em epistemologias contemporâneas mostrou-se um material didático capaz de envolver o estudante em discussões relevantes sobre as propriedades dos materiais supercondutores, suas aplicações, bem como sobre o aspecto epistemológico abordado, percebidos através das opiniões emitidas pelos alunos durante as aulas, pelo interesse demonstrado no decorrer do processo e pelo seu desempenho em testes de conhecimento. / In this work we describe the conception and development of a webpage about superconductivity, as well as its implementation in a third high school grade of Frederico Jorge Logemann school., in Horizontina/RS. In order to make this development were needed some hypermedia resources and the webpage represents the educational product of this dissertation. The implementation of the theme is the result of contemporary epistemologies that question naive views about the nature of science. Thus, we consider the epistemologies of Popper (1993), Kuhn (1978), Lakatos (1978) and Laudan (1977) because of their relevance in Physics teachings, emphasizing the principal convergence that exists among these theories: the opposition to the empiricism-inductive theory. As a theoretical psychological framework, we used the social-historical psychology of Vygotsky to a better comprehension of the learning-teaching process involved in this work. We have evaluated the implementation of the project from instruments that make evident the students’ meaningful learning about the theme. The metodology used during the classes, which approached the subject, was based, basically, on the utilization of the webpage developed to this end, as well as on the achievement of experimental activities, by the students, in order to see the practical part involved in the experiment assembling and the results that were found in it. From the animations that were available in the didactic materials, the idea was to promote the comprehension of the phenomenon and its consequences. The webpage that was made and based on the contemporary epistemologies appeared unveiled a didactic material that is able to involve the student in relevant discussions about the properties of the superconductor materials, their applications, as well as about the epistemological aspect that was approached, all this data was realized throw the students’ oppinion during the classes, by their interest showed during the process and by their performance in knowledge tests.