980 resultados para frequency domain decomposition


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The frequency of viral markers for hepatitis B (HBV) and C (HCV), human immunodeficiency virus-1 (HIV-1) and human T-lymphotropic virus-1 (HTLV-1) was evaluated in 32 Brazilian ß-thalassemia multitransfused patients. Additionaly the serum concentrations of ferritin and alanine aspartate transaminase (ALAT) were determined. The results show a high prevalence of markers of infection by HBV (25.0%) and HCV (46.8%) and a low prevalence of markers for HIV-1 and HTLV-1. No correlations were demonstrated between the presence of the hepatitis markers and the number of units transfused or the serum concentrations of ferritin and ALAT.

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Risk Based Inspection (RBI) is a risk methodology used as the basis for prioritizing and managing the efforts for an inspection program allowing the allocation of resources to provide a higher level of coverage on physical assets with higher risk. The main goal of RBI is to increase equipment availability while improving or maintaining the accepted level of risk. This paper presents the concept of risk, risk analysis and RBI methodology and shows an approach to determine the optimal inspection frequency for physical assets based on the potential risk and mainly on the quantification of the probability of failure. It makes use of some assumptions in a structured decision making process. The proposed methodology allows an optimization of inspection intervals deciding when the first inspection must be performed as well as the subsequent intervals of inspection. A demonstrative example is also presented to illustrate the application of the proposed methodology.

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Dissertação apresentada para obtenção do Grau de Doutor em Engenharia Electrotécnica, Especialidade de Sistemas Digitais, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

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Thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the subject of Electrical and Computer Engineering

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As it is widely known, in structural dynamic applications, ranging from structural coupling to model updating, the incompatibility between measured and simulated data is inevitable, due to the problem of coordinate incompleteness. Usually, the experimental data from conventional vibration testing is collected at a few translational degrees of freedom (DOF) due to applied forces, using hammer or shaker exciters, over a limited frequency range. Hence, one can only measure a portion of the receptance matrix, few columns, related to the forced DOFs, and rows, related to the measured DOFs. In contrast, by finite element modeling, one can obtain a full data set, both in terms of DOFs and identified modes. Over the years, several model reduction techniques have been proposed, as well as data expansion ones. However, the latter are significantly fewer and the demand for efficient techniques is still an issue. In this work, one proposes a technique for expanding measured frequency response functions (FRF) over the entire set of DOFs. This technique is based upon a modified Kidder's method and the principle of reciprocity, and it avoids the need for modal identification, as it uses the measured FRFs directly. In order to illustrate the performance of the proposed technique, a set of simulated experimental translational FRFs is taken as reference to estimate rotational FRFs, including those that are due to applied moments.

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Mestrado em Engenharia Civil – Ramo Estruturas

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Um dos princípios da Gestão é: “If you cannot measure it, you cannot improve it.” In The Economist – 26.Dez.2008, idea of 19th century English physicist Lord Kelvin. Embora seja uma afirmação aplicável à gestão económica, também pode ser utilizada no domínio da gestão da energia. Este trabalho surge da necessidade sentida pela empresa Continental - Industria Têxtil do Ave, S.A. em efetuar uma atualização dos seus standards de produção, minimizando os seus consumos de eletricidade e gás natural. Foi necessário efetuar o levantamento dos consumos em diversas máquinas e equipamentos industriais, caracterizando e analisando os consumos ao longo de todo o processo produtivo. Para o tratamento de dados recolhidos foi desenvolvida uma folha de cálculo em MS Office ExcelTM com metodologia adequada ao equipamento em análise, que dará apoio ao decisor para a identificação dos aspetos que melhorem o processo produtivo e garantam uma elevada eficiência energética. Porém, não se enquadra no âmbito do Plano Nacional de Racionalização de Energia, sendo uma “auditoria energética” ao processo produtivo. Recentemente, a empresa, tem vindo a utilizar equipamentos eletrónicos que permitem otimizar o funcionamento mecânico dos equipamentos e das potências instaladas dos transformadores, na tentativa de racionalizar o consumo da energia elétrica. Outros equipamentos como, conversores de frequência para controlo de motores, balastros eletrónicos que substituem os convencionais balastros ferromagnéticos das lâmpadas de descarga fluorescente, têm sido incluídos ao nível das instalações elétricas, sendo gradualmente substituída a eletromecânica pela eletrónica. Este tipo de soluções vem deteriorar as formas de onda da corrente e da tensão do sistema pela introdução de distorções harmónicas. Faz ainda parte deste trabalho, um estudo de uma solução que melhore, simultaneamente o fator de potência e reduza as harmónicas presentes num posto de transformação localizado no seio da fábrica. Esta solução, permite melhorar a qualidade da energia elétrica e as condições de continuidade de serviço, garantindo melhores condições de exploração e incrementando a produtividade da empresa.

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Dissertation submitted in partial fulfilment of the requirements for the Degree of Master of Science in Geospatial Technologies.

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The frequency of microorganisms identified in nosocomial infections at Unicamp University Hospital from 1987 to 1994 was analysed. The most common microorganism was S. aureus (20.9%), which was found in surgical wound, bloodstream and arterial-venous infections. In urinary tract infections (UTI), gram-negative rods (56.5%) and yeasts (9%) predominated. A. baumannii isolates were observed to have increased in the last three years. There was a gradual increase in the frequency of coagulase-negative staphylococci and A. baumannii in bloodstream infections but there wasn’t any change in Candida sp

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In order to evaluate the distribution of dermatophytes in Porto Alegre, the capital of the state of Rio Grande do Sul, Brazil, they were isolated from the skin, hairs and nails samples and retrospectively analyzed from June 1981 to June 1995, in two different institutions in the city of Porto Alegre: (i) the Serviço de Micologia do Instituto de Pesquisas Biológicas Jandyr Maya Faillace, da Secretaria de Saúde e Meio Ambiente do Rio Grande do Sul which attends the low income population (low and middle classes) and, (ii) Laboratório Weinmann, a clinical pathology laboratory which attends predominantly the higher income population (middle and upper classes), both which attend in the metropolitan area of Porto Alegre. The dermatophyte predominance of Trichophyton rubrum was confirmed (55.33%) followed by T. mentagrophytes (21.46%). The data obtained were compared with the existing prevalence data which were collected in the interior of the state over a period of 32 years (1960-1992). T. verrucosum, T. simii, Microsporum persicolor, T. schöenleinii, M. nanum and M. cookei were isolated in the interior and have not been found in the capital so far. On the other side, T. violaceum was, isolated in the capital and has not been found in the interior so far.

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Thesis submitted to Faculdade de Ciências e Tecnologia of the Universidade Nova de Lisboa, in partial fulfilment of the requirements for the degree of Master in Computer Science

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Proceedings Institute of Acoustics (UK); vol. 25, nº2, p. 72-78.

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Due to the lack of studies about neurocysticercosis in the South of Brazil, an investigation was conducted to determine the percentage of suspected cases of neurocysticercosis in computed tomography diagnoses in Santa Maria, RS, from January 1997 to December 1998. Of 6300 computed tomographies (CT) of the skull performed at the private Hospital de Caridade Astrogildo de Azevedo, 80, i.e., 1.27% were suspected of neurocysticercosis. Fifty were women (62.5%) and 30 were men (37.5%). The most frequent radiological manifestation indicating neurocysticercosis was the presence of calcifications (isolated or associated), with a 95% rate (76 cases), while the presence of hypodense lesions reached a 5% rate (4 cases). After routine analysis, each CT was evaluated again and the suspected cases were confirmed. The percentage of suspected cases of neurocysticercosis detected by CT in the present study carried out in Santa Maria was considered low (1.27%). This can be explained by the fact that tomography is not accessible to the economically underprivileged population of Santa Maria. We hope that the present study can alert the population and the professionals to the fact that neurocysticercosis is a more frequent disease than indicated by the few diagnoses made.

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Dissertation submitted in partial fulfilment of the requirements for the Degree of Master of Science in Geospatial Technologies