18,721 research outputs found
Conversores CC-CC com elevada taxa de conversão estática
Full text linkTese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Elétrica, Florianópolis, 2014.Nesse trabalho é introduzida uma nova família de Conversores CC-CC com elevada taxa de conversão estática. Tais conversores tem origem a partir dos Conversores CC-CC básicos convencionais (Buck, Boost, Buck-Boost, Zeta, Cúk e Sepic), no qual inserindo a célula básica de comutação proposta no trabalho, é possível tornar esses conversores convencionais em conversores com elevada taxa de conversão estática, gerando os Conversores Propostos. A célula de comutação responsável por gerar a família de Conversores Propostos possui apenas semicondutores passivos, o que é uma vantagem para essas topologias. Além disso, a família de Conversores Propostos possui a vantagem de ser simétrica, isso possibilita a reflexão dos componentes superiores, gerando os componentes inferiores das novas estruturas. Essa reflexão é uma característica importante nas topologias propostas, pois reduz os esforços de tensão em seus interruptores. Seguindo a nomenclatura básica, os conversores propostos são chamados de: Duplo Buck Quadrático, Duplo Boost Quadrático, Duplo Buck-Boost Quadrático, Duplo Zeta Quadrático, Duplo Cúk Quadrático e Duplo Sepic Quadrático. Dos sete Conversores Propostos no trabalho, somente um não é originado pela célula básica de comutação. Este Conversor é chamado de Duplo Buck Quadrático Básico, e foi importante para consolidar os estudos dos Conversores CC-CC com elevada taxa de conversão estática. Algumas análises como etapas de operação em condução contínua, ganho estático e característica externa são apresentadas para todos os conversores propostos. Para provar as análises teóricas, os resultados experimentais em malha aberta são apresentados para o Conversor Duplo Buck Quadrático Básico, e em malha aberta, malha fechada e malha fechada com desequilíbrio de carga para o Conversor Duplo Boost Quadrático.<br
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
Synthesis and characterization of C-60-anchored multiarmed polymers with well-defined structures
No full text
Improving interoperability in distributed and physical union catalogues through co-ordination of cataloguing and indexing policies : report for work package B of the JISC CC-interop project
Full text linkThis report addresses section 7.2.4 (Guidelines and Strategy for Cataloguing and Indexing Standards) of the CC-interop project plan and fulfills deliverable B3 of work
package B
Molecular modification on dye-sensitized solar cells by phosphonate self-assembled monolayers
No full text[[abstract]]Molecular modification by phosphonic acids forms phosphonate dipole layers on TiO2 and influences photoelectrochemical characteristics of DSSCs. V-oc is dipole-related and eta is dominated by V-oc. A phosphonic acid with a negative dipole moment shifts the TiO2 E-CB closer to the vacuum level and causes a larger V-oc. A higher E-CB increases the E-F gradient and results in a larger J(sc). APPA has the largest negative dipole moment, so the APPA-modified DSSC shows the largest V-oc and J(sc), and the highest eta. The dark currents of modified DSSCs are not just dipole-related. They are dominated mainly by the electron tunneling effect. A shorter phosphonate dipole layer offers a smaller tunneling barrier and makes reverse electron injection easier. So the CEPA- and APPA-modified DSSCs show smaller charge transfer impedances at the TiO2/dye/electrolyte interfaces and larger dark currents than the other four modified DSSCs. Although the TFBPA dipole layer is not the longest, the TFBPA-modified DSSC exhibits the largest impedance and smallest dark current because the charge recombinations at the interface and reverse injection of electrons are suppressed by the strong electron-withdrawing property.[[note]]SC
Course Syllabus TXA 436-Sp05
No full textTXA 436, Textile Chemistry, Course Syllabus by Instructor CC Chu, Spring 200
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