7,067 research outputs found
Foreign funding to an emerging market: the Monetary Premium Theory and the Brazilian Case, 1991 - 1998
Simulação e optimização de tempo de recuperação de um modulador de impulso de alta tensão
presente dissertação tem como objectivo a análise e simulação de um Modulador de Impulso de Alta Tensão (este circuito tem como finalidade substituir o modulador actual do ISOLDE/CERN), utilizando programas de simulação e de implementação de modelos matemáticos respectivamente no Orcad-Pspice e o Matlab-Simulink.
Estudou-se o modulador de impulso de alta tensão projectado para o ISOLDE/CERN, e analisou se o seu funcionamento em função do tempo de recuperação e sobreelevação da tensão na carga, os dois parâmetros mais importantes do sistema.
Descreveu-se a operação do modulador de impulso de alta tensão baseado no gerador de MARX, desenvolvido no ISEL em pareceria com o CERN, estudou-se o funcionamento deste tipo de circuito baseado na tecnologia de semicondutores.
Desenvolveu-se um modelo matemático que descreve a operação do modulador e implementou-se em MATLAB. Fez-se uma análise comparativa dos resultados obtidos experimentalmente com os de simulações obtidos em MATLAB e em PSPICE, e estudaram-se as limitações destes programas na análise do circuito
BREVE ANÁLISE DO ENSINO SUPERIOR : PERSPECTIVAS E TENDÊNCIAS ATUAIS.
As universidades ao longo do tempo têm sofrido mudanças significativas em sua forma de gestão e administração do conhecimento, especialmente após a adoção do modelo econômico neoliberal e a chamada crise da pós-modernidade. Esse modelo atual tem norteado as políticas públicas e suas diversas formas de gestão universitária para um caminho atual , ao mesmo tempo incerto. Com o objetivo principal de verificar esse(s) novo(s) caminho(s), o presente artigo utilizou-se da metodologia de revisão bibliográfica sobre o tema em questão e foram verificados autores como: LAMARRA (2009), LINDO (1998), RAMA (2009) , entre outros que têm observado esses (des)locamentos na atualidade e contribuído significamente para o entendimento dessas novas tendências, entre elas a do “voluntarialismo ideológico” , necessário a construção da sociedade na atualidade
Quarkonium production at the LHC: a phenomenological analysis of surprisingly simple data patterns
The LHC quarkonium production measurements reveal a startling observation:
the J/, (2S), and (nS) -differential cross sections are compatible with one universal momentum
scaling pattern. Considering also the absence of strong polarizations of
directly and indirectly produced S-wave mesons, we are led to the conclusion
that there is currently no evidence of a dependence of the partonic production
mechanisms on the quantum numbers and mass of the final state. The experimental
observations supporting this universal production scenario are remarkably
significant, as shown by a new analysis approach, unbiased by specific
theoretical calculations of partonic cross sections, which are only considered
a posteriori, in comparisons with the data-driven results.Comment: Submitted to Phys. Lett.
Possible climate change impacts on water resources availability in a large semi-arid catchment in Northeast Brazil.
The semiarid region of Northeast Brazil is characterized by water scarcity, vulnerability of natural resources, and pronounced climatic variability. An integrated model has been developed to simulate this complex situation with an emphasis on a large-scale representation of hydrological processes and on the sensitivity to climate change. Regional climate change scenarios were obtained by empirical downscaling with large-scale climate information from different GCMs which differ strongly in their projections for future precipitation. The results show that due to these differences, it is still impossible to give quantitative values of the water availability in a forecast sense, i.e. to assign probabilities to the simulated results. However, it becomes clear that efficient and ecologically sound water management is a key question for further development. The results show that, independent of the climate change, agriculture is more vulnerable to drought impacts in the case of rainfed compared to irrigated farming. However, the capacity of irrigation and water infrastructure to enhance resilience with respect to climatic fluctuations is significantly constrained in the case of a negative precipitation trend
Forecasting elections in a multiparty system : the case of Portugal and Brazil
Mestrado Bolonha em Econometria Aplicada e PrevisãoThis work tries to forecast election results in Brazil and Portugal using two bayesian models and one frequentist in order to find out which one has better results. We will use older election‘s results and polls in order to check if there are sistematical biases towards certain parties. We also use macroeconomical data to check how influential this data is to forecast election. The analysis pointed out that there are no sistematical biases for any party in any polling company. We also found out that there is no significant relationship between macroeconomic data and the election results in these countries. Furthermore, the fact that both examples had few elections and have a lot of parties which are constantly being created and dismissed, there is not a "perfect" model, however, they all have very acceptable results.info:eu-repo/semantics/publishedVersio
Information practices: the relevance of the concept to information user studies
The concept of information practices and the recent perspective of studies on information users are discussed. A framework of the human and social sciences from where the concept originated is presented. The history of the studies of information users with the notions of "use studies" and "information behavior", show that the approach of information practices differs. Finally, some recent studies in informational practices are described and discussed
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