Large-eddy simulation of turbulent flow over a parametric set of bumps

Turbulent flow over a series of increasingly high, two-dimensional bumps is studied by well-resolved large-eddy simulation. The mean flow and Reynolds stresses for the lowest bump are in good agreement with experimental data. The flow encounters a favourable pressure gradient over the windward side of the bump, but does not relaminarize, as is evident from near-wall fluctuations. A patch of high turbulent kinetic energy forms in the lee of the bump and extends into the wake. It originates near the surface, before flow separation, and has a significant influence on flow development. The highest bumps create a small separation bubble, whereas flow over the lowest bump does not separate. The log law is absent over the entire bump, evidencing strong disequilibrium. This dataset was created for data-driven modelling. An optimization method is used to extract fields of variables that are used in turbulence closure models. From this, it is shown how these models fail to correctly predict the behaviour of these variables near to the surface. The discrepancies extend further away from the wall in the adverse pressure gradient and recovery regions than in the favourable pressure gradient region

Optimal Design of Thin-film Plasmonic Solar Cells using Differential Evolution Optimization Algorithms

International audienceAn approach using a differential evolution (DE) optimization algorithm is proposed to optimize design parameters for improving the optical absorption efficiency of plasmonic solar cells (PSC). This approach is based on formulating the parameters extraction as a search and optimization process in order to maximize the optical absorption in the PSC. Determining the physical parameters of three-dimensional (3-D) PSC is critical for designing and estimating their performance, however, due to the complex design of the PSC, parameters extraction is time and calculation intensive. In this paper, this technique is demonstrated for the case of commercial thin-film hydrogenated amorphous silicon (a-Si:H) solar photovoltaic cells enhanced through patterned silver nano-disk plasmonic structures. The DE optimization of PSC structures was performed to execute a real-time parameter search and optimization. The predicted optical enhancement (OE) in optical absorption in the active layer of the PSC for AM-1.5 solar spectrum was found to be over 19.45% higher compared to the reference cells. The proposed technique offers higher accuracy and automates the tuning of control parameters of PSC in a time-efficient manner

The importance of the industrialization of Brazilian shale when faced with the world energy scenario

Esse artigo discute a importância da industrialização do xisto brasileiro, tendo, como base, fatores como: seguridade do sistema de energia nacional, a geopolítica mundial do petróleo, quantidade dos recursos, custo de produção, preço do petróleo, impactos ambientais e as reservas de petróleo nacionais. O trabalho mostra que a industrialização do xisto sempre surge quando questões como as do peak oil ou da geopolítica do petróleo aparecem como fatores que colocam o preço do barril de petróleo em patamares irreais. O artigo conclui que, para o caso do Brasil, o xisto pode ser classificado como recurso estratégico, viável economicamente, graças ao sucesso no desenvolvimento da tecnologia de retortagem para extração do óleo, do volume de recursos e do preço do barril de petróleo. O artigo apresenta, também, a conclusão de que o xisto pode ser o fator impulsionador para a formação de um parque tecnológico em São Mateus do Sul, necessário devido à dependência econômica do município em relação à Petrosix.This article discusses the importance of the industrialization of Brazilian shale based on factors such as: security of the national energy system security, global oil geopoliticsl, resources available, production costs, oil prices, environmental impacts and the national oil reserves. The study shows that the industrialization of shale always arises when issues such as peak oil or its geopolitics appear as factors that raise the price of oil to unrealistic levels. The article concludes that in the Brazilian case, shale oil may be classified as a strategic resource, economically viable, currently in development by the success of the retorting technology for extraction of shale oil and the price of crude oil. The article presents the conclusion that shale may be the driving factor for the formation of a technology park in São Mateus do Sul, due to the city's economic dependence on Petrosix

Práticas de sucessão e herança no contexto urbano da cidade de Maputo

Tese de Mestrado em Antropologia Social e Cultural, apresentada à Universidade de Lisboa, através do Instituto de Ciências Sociais em 2011Esta dissertação aborda a questão da sucessão e herança na sequência da morte de um homem na área do «Grande Maputo» - Moçambique. Procura-se perceber as dinâmicas de herança e sucessão entre pessoas que vivem num contexto inter cultural urbano, onde quando as pessoas se casam e morrem são confrontadas com diferentes sistemas e pressupostos de herança e sucessão. De forma particular, esta dissertação é sobre como as pessoas em contextos inter culturais cada vez mais complexos, manipulam as normas para, por um lado, assegurar a inserção familiar e, por outro lado, satisfazerem perspectivas individuais. Nela, são igualmente analisadas as estratégias, práticas e conflitos inerentes à transmissão de bens e estatutos