Calcified skeletons are produced within complex assemblages of proteins and polysaccharides whose roles in mineralization are not well understood. Researchers have long postulated that living organisms utilize the macromolecules of organic matrices to actively guide the formation of crystal structures. The timing and placement of the subsequent minerals that form are most easily controlled during nucleation; however, a physical and chemical picture of how organic functional group chemistry influences the initial stages of nucleation is not yet established. These processes are further complicated by the realization that carbonate biominerals can form by an amorphous to crystalline transformation process, which has prompted the question of how chemical signatures are recorded during mineralization. Investigations of mineralization processes such as the kinetics of nucleation and the transformation of amorphous calcium carbonate (ACC) to crystalline products are critical to building a better understanding of biomineral formation. Only from that fundamental basis can one begin to decipher changes in climate and seawater chemistry over geologic time and by recent anthropogenic effects. This dissertation presents the findings from experimental studies of the thermodynamics and kinetics of multiple mineral formation processes, including nucleation and transformation from an amorphous phase. The kinetics of calcite nucleation onto a suite of high-purity polysaccharide (PS) substrates were quantified under controlled conditions. Nucleation rates were measured as a function of 1) supersaturation extending above and below ACC solubility and 2) ionic strength extending to seawater salinity. These conditions decipher the chemical interactions between the PS substrate, calcite crystal, and solution. These investigations show the energy barrier to calcite formation is regulated by competing interfacial energies between the substrate, crystal, and liquid. The energy barriers to nucleation are PS-specific by a systematic relationship to PS charge density and substrate structure that is rooted in minimization of the competing substrate-crystal and substrate-liquid interfacial energies. The data also suggest ionic strength regulates nucleation barriers through substrate-liquid and crystal-liquid interfacial energetics. In a second experimental study, stable isotope labeling was used to directly probe the transformation pathway. Four processes were considered: dissolution-reprecipitation, solid-state, or combinations of these end member processes. Isotope measurements of calcite crystals that transform from ACC have signatures that are best explained by dissolution-reprecipitation. The extent of isotopic mixing correlates with the amount of ACC transferred and the time to transformation, suggesting the calcite crystals are recording the changing local solution environment during the transformation. These investigations into different mineralization mechanisms build a framework for how functional group chemistries of organic molecules regulate mineralization and the resulting isotopic and elemental signatures in the calcite. This may provide useful insights to interpreting chemical signatures of carbonate biominerals in fossil record and understanding ocean chemistry changes throughout geologic time. / Ph. D.

Orientadores: Raul Vinhas Ribeiro, Maria Silvina Medrano / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-08T21:31:35Z (GMT). No. of bitstreams: 1 Giansante_Moacir_M.pdf: 31760626 bytes, checksum: 1c3f355aabddb68180939401b269973f (MD5) Previous issue date: 2007 / Resumo: Este estudo apresenta uma metodologia para calcular os custos decorrentes de projetos de universalização de serviços de telecomunicações, conforme estabelece a legislação brasileira, denominados como custos líquidos em outras legislações. Tal conceito é baseado na obtenção dos custos evitáveis e para seu cálculo, os custos atribuídos ao cumprimento das obrigações devem ser alocados de forma a guardar relação com a atividade que o gerou bem como com a quantidade de serviços/produtos produzidos. A metodologia também deve ser capaz de capturar economias de escala e de escopo decorrentes de compartilhamento de recursos e de otimização das capacidades instaladas. Por isso, propõe-se um modelo que combine os conceitos de custos incrementais e de custos prospectivos de longo prazo de forma flexível e que permita a análise de diferentes projetos de universalização / Abstract: This study presents a methodology to calculate the net costs resulting from telecommunications universal services, in accordance with Brazilian legislation. Such a concept is based on the estimation of the avoidable costs due to universal obligations. In order to proceed with the calculations, the costs attributed to these obligations should be allocated to guard relation with the activity that generated them as well as with the quantity of service/productsproduced. ,The methodology also should be capable of capture scale and scope economies due to shared resources or capacities optimization. Theproposed model combines the concepts of incremental costs andforward-looking costs in aflexible manner to enable the analysis of different projects regarding universal service / Mestrado / Automação / Mestre em Engenharia Elétrica

Orientadores: Saul Barisnik Suslick, Denis Jose Schiozer / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica, Instituto de Geociências / Made available in DSpace on 2018-08-12T08:07:04Z (GMT). No. of bitstreams: 1 Avansi_GuilhermeDaniel_M.pdf: 1362823 bytes, checksum: 732bf257c2ca9c9de80531fdd59770e5 (MD5) Previous issue date: 2008 / Resumo: O processo tradicional de estratégia de produção demanda muitas simulações, devido ao alto número de variáveis e combinações. Devido à impossibilidade de investigar todas as alternativas, processos tradicionais levam a resultados sub-ótimos. Processos automatizados podem resolver em partes esse problema, porém o tempo computacional se eleva devido ao acréscimo do número de simulações geradas no processo. Dentro desta perspectiva, este trabalho propõe uma metodologia de aplicação de metamodelos no processo de estratégia de produção e na avaliação econômica de campos de petróleo, possibilitando um número maior de alternativas e aumentando as chances de melhores decisões na escolha da estratégia de produção de campos de petróleo, sendo que metamodelos já foram utilizados em outras áreas (análise de risco, ajuste de histórico etc.). Os metamodelos estudados e aplicados envolvem: métodos estatísticos; planejamento estatístico; metodologia de superfície de resposta e teste de consistência. Os metamodelos utilizados neste trabalho mostraram que podem ser utilizados para seleção de estratégias de produção, trazendo uma opção adicional ao processo além de encontrar soluções que não são observadas pelos métodos tradicionais, e que permitiu mudar a decisão utilizada no processo de avaliação econômica em um amplo espaço de solução / Abstract: The traditional process of production strategy demands many simulations due to the high number of variables and possibilities. Sub-optimal results can be obtained from manual processes; Automatic processes can mitigate this problem but the computational effort increases as a result of the number of simulations generated in the process. Thus, the objective of this work is an attempt of application of proxy models in the production strategy optimization and in the economic evaluation in petroleum fields, allowing the selection of production strategy evaluating a higher number of alternatives and increasing the chances to find better solutions. Proxies have been used in important applications such as risk analysis, history matching etc. The applied proxy models combine the following components: statistics methods, experimental planning, the response surface methodology and consistency checking. We have shown that proxy models can be used in a definition of production strategy, bringing an additional option in the process. The advantage is to find solutions that are not investigated by the traditional methods; proxy models create new possibilities to change a decision used in an economic evaluation process in a wider solution space / Mestrado / Reservatórios e Gestão / Mestre em Ciências e Engenharia de Petróleo