Orientador: Alberto Martins Jorge / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-09T06:08:51Z (GMT). No. of bitstreams: 1 Fregonezi_MarcoAurelioSeluque_D.pdf: 1915759 bytes, checksum: 98d687449ed74b262089ad5797a9321d (MD5) Previous issue date: 2006 / Resumo: Este trabalho consiste na análise de regras de síntese e minimização de funções digitais multi-valores e na criação de um software para a realização automatizada da síntese empregando as regras criadas e, também, na criação de um software para simulação de portas lógicas e circuitos digitais multi-valores. Todas essas ações são coerentes entre si. A partir de uma tabela verdade, pode-se gerar uma expressão algébrica por meio do software que realiza a síntese; a partir dessa expressão, pode-se construir um circuito no simulador lógico criado para a observação do resultado; pode-se, também, usar um simulador analógico (SPICE ¿, por exemplo) para verificar a viabilidade da implementação física do circuito. Observa-se que o resultado obtido no simulador analógico é igual ao obtido no simulador lógico criado, que também é coerente com a tabela verdade original / Abstract: This work consists in the investigation of rules for synthesis and minimization of digital multi-valued functions; in the creation of a software for automated performing of synthesis applying the proposed rules and also of a software for multi-valued logic gates and circuits simulation. All those features are jointly coherent. Starting with a truth-table, it is possible to generate an algebraic expression using the implemented software; starting from that expression, a circuit can be constructed using the created logic simulator to analyze the result. An analogical simulator (like SPICE ¿, for example) can be used to verify the viability of the circuit physical implementation. It is observed that the result obtained with the analogical simulator is equivalent to the result from the logic simulator; with is also coherent to the given truth table / Doutorado / Eletrônica e Microeletrônica / Doutor em Engenharia Elétrica

The future energy demand will require a change in the current energy supply. In this regard, the production of hydrogen by photoelectrochemical solar cells is a promising alternative because the fuel is obtained from water and, importantly, its combustion is free of carbon. Many metal oxides, including those having a complex stoichiometry (i.e. ternary oxides) behave as semiconductors and present good stability in aqueous environments, making them attractive candidates for water splitting devices. This thesis focuses on the preparation and study of ternary metal oxide materials as photoelectrodes for water splitting, with emphasis on photocathodes. These materials must meet the requirements for a practical device: low cost, non-toxicity, made of Earth abundant elements, environmentally friendly, etc. The thesis also aims at the study of strategies to improve their photoelectrochemical response. lt comprises the investigation of the kinetics of hydrogen generation reaction and the characteristics of the electrode solution interface by photoelectrochemical impedance spectroscopy. The main points can be summarized as: (i) the effect of an electrochemical oxidative pretreatment in CuFe2Ü4 photocathodes (ii) the investigation of water splitting mechanisms in CaFe2Ü4 photocathodes, (iii) the effect of metal doping in LaFeO3 photocathodes (iv) the study of the photoelectrochemistry of compact and nanoparticulate YFeO3 photocathodes and (v) the effect of a reductive electrochemical treatment in NiTiO3 photoanodes, and comparison with the effect of the treatment in anatase electrodes.