941 resultados para correntes neutras
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Information organization can be considered as a nuclear area in Information Science and its historical background has been historically built based on three theoretical approaches: subject cataloguing, under a North-American influence, Indexing, under a British influence, and document analysis, under a French influence. In this sense, although one can consider the strong influence of the logic-linguistic approach of the French tradition in information organization both in Brazil and in Spain, it is not already clear in what extent the mentioned influence specifically occurs in Brazil and Spain as well as what are the dialogical perspectives between them. So, and in order to analyze how the Information Science academic environments in Brazil and in Spain conceive the interdisciplinary relationships in the domain of document analysis (DA), it was applied a questionnaire to Brazilian and Spain DO researchers based on the records of the Brazilian and the Spanish International Society for Knowledge Organization chapters. The results (64,5% of answers in Brazil and 60,6% in Spain) allowed the identification of 35 DA interdisciplinary relationships in Brazil and 98 in Spain, whose data were so grouped in 7 matrixes ? cognitive, philosophical, historical, logic-lingusitic, quantitative, social and political, and technological. It was possible to observe that the logical-linguistic matrix is strongly predominant (90% of the answers in Brazil and in Spain) what reflects the influence of the ideas of Jean-Claude Gardin. On the other side, the graphic visualization of authors´s network showed a strong perspective of dialogical relationships among Brazilian and Spanish DA researchers, based on the convergence of theoretical conceptions, what allow us to conclude the need of joint research policies between both coountries in order to make the mention ed dialogical relationships real and fruitful.
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Considering document analysis as one of the theoretical approaches of information organization, besides subject cataloguing and indexing it carries out a theoretical research on its conceptual dimension as a background to a further analysis of the Brazilian academic environment specially in terms of conceptions of document analysis as well as its interdisciplinary relationships. The results reveal a strong theoretical influence of Jean-Claude Gardin´s ideas which are deeply devoted to the processes involved in document analysis. It also confirms the high level of interdisciplinary relationships to Logical-linguistic disciplines. Neverthless, it feels the need of the Brazilian researches in assuming their theoretical influences in such a way to minimize the huge terminological diversity while naming the specific concepts of the area.
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Information Science (IS) research has strongly grown in Brazil, in the last decade, and, as a consequence, it was possible to observe a growth of the support given by the Brazilian National Scientific and Technological Development Council - CNPq. In this sense, this paper aims to analyze the scientific production (journal papers) of the 15 IS researchers who have the highest level research fellowships during the period between 2001 and 2010. Data were analyzed in terms of bibliographic dispersion, internationalization, and scientific collaboration as well as in terms of the most prominent journals. The results (219 papers) evidence an average of around 1.5 papers per author per year and a group of 63 different journals (60% evaluated under levels Qualis A1 and B1). The journal DataGramaZero is strongly present since it responds for 22% of the whole production. It was possible to observe a still shy presence of foreign journals and none of them belong to the Anglo-Saxon environment. The kind of authorship is well-balanced between individual and collective ones, including inter-institutional collaboration. It is possible to conclude that this group is mature and very productive, and it represents an academical IS leadership in Brazil but still lacks more international visibility.
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This research aims at analyzing the researchers with major insertion and impact within the GT7 ENANCIB community, through an analysis study of citation and co-citation from 2003 to 2010. We propose to highlight the researchers cited in a greater number of papers, as well as the number of citations received. Also, to describe the co-citation network intending to analyze the interlocution network built by the writers towards the cited ones and calculate the indicators of density and centrality of the network. As for the theoretical-methodological basis, we used the Domain Analysis (D.A.), seen as the reflexion of a discourse community. Among the 11 approaches about D.A, the bibliometric studies stand out. Data from the 124 researches presented in the period of this study showed 1446 cited researches for a total of 2307 citations. From the total number of cited researchers in a greater number of papers, 33 were considered authors of major impact and visibility, being cited in at least 8 papers, thus getting at least 8 citations. The software Ucinet was used to map and visualize the net of interlocution established by the citing papers. As for the results, we could notice that, from the total of 33 researchers, 23 are Brazilian, 20 take part in Post-Graduation Programs and 11 are granted CNPq scholarships of productivity. Furthermore, we highlighted the most cited themes and analyzed the relationship involving the number of citations according to the number of papers in which the researcher was cited and the number of researches cited from each researcher. Regarding the network structure, we could observe that the authors form a single component, indicating that the group of researchers co-cited reveals proximity and theoretical, conceptual and methodological articulations. We concluded that the citing community adopts ordinary theoretical schools; moreover, we might characterize the core of the known researchers as a foundation for the knowledge of the GT7 theme.
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Pós-graduação em Engenharia Elétrica - FEB
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Pós-graduação em Engenharia Mecânica - FEG
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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This work aims to analyze data from a Natural Electric Potential landfill type ditch located in Cordeirópolis (SP). The procedure measures initially involved the assembly and installation of an apparatus cables, sensors and drain geophysical measurements and flow rate of biogas in a ditch later filled by solid waste. Biogas is a product of degradation of organic matter in waste by the action of microorganisms in an anaerobic environment. Its features high methane content in the gas potentially usable as fuel in energy generation systems or steam. The study area is characterized by clayey soil composition change from the diabase sill correlated to the event Serra Geral Formation siltstones overlapping Tatuí with groundwater level site around 50m. The cables were installed vertically in parallel with drain gas manifold, which allowed the collection of data by the technique geophysical logging every 15 days over a period of eight months. For data analysis we used four parameters in the study, the closing time of the ditch, natural electric potential, the flow velocity of biogas and rain. With the tabulated data plots were constructed for each collection day showing values in the range of the cable is in contact with waste (200 cm - 400 cm) and range of the cable in contact with the soil (600 cm - 800 cm). Subsequently graphs were generated with the period of eight months to analyze the data tabulated. A statistical correlation data, which show the influence of rainfall on the production of biogas. The results were satisfactory and demonstrated the feasibility of the research method in studies for the feasibility analysis for the capture of biogas energy
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This study aims to analyze the feasibility of using predictive techniques like thermography, vibration analysis, eddy current, liquid penetrant, visual examination and ultrasound in equipment as batch reactors of the type used in a biodiesel production company. This study is based on: analysis of the practices of corrective and preventive maintenance commonly adopted in the company in question, the cost and time spent for such activities and the potential savings and revenue generation that can be after implementation of these techniques on the analysis of maintenance current
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This paper presents the study on the application of the electrolytic plasma for surface treatment of aluminum. A bibliographical study on the material of interest was preliminarily performed and later designed and built an electrolytic cell, including the excitation source. Unlike conventional electrolysis process, the plasma assisted carry on in the non-linear region of characteristic current/voltage curve. Therefore it requires for the on set of the process that the power supply operates on harder conditions than those on high current process. The plasma produced during the present investigation has temperatures in the range o 6,0.10 3 -7,0 .10 3 K, well above those found in conventional chemical process. It also shows a particular dynamic to promote changes on surface and to produce new materials. The plasma is generated by microdischarge in vapor or gas bubbles involved in physic-chemical processes in electrode regions of the electrolytic cell. The electrode material was the aluminum (7075). The Process Electrolytic Plasma Processing (EPP) is sensitive to various parameters such as operating voltage, current density, electrolyte, concentration of electrolyte, geometry of reactor, temperature of electrolytic solution and dynamic of the fluid in the cell. The experiments were carried on in order to find parameters for a stable abd steady operation. The choice for the electrolytic was silicate/alkali solution in various concentrations to operate in various voltage as well. Plasma was produced on negative (cathode) and positive (anode) electrode, in specific conditions. A stable operation on the cathode process was obtained with low concentration of the electrolytic in aqueous solution, current density around 250V effective voltage. For the evolution of plasma in anodic process it was required higher concentrations and higher... (Complete abstract click electronic access below)
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A parameter commonly used in investigations of environmental magnetism is the magnetic susceptibility (MS), which is the quantitative measure of the ability of magnetization of a specific material in the presence of an induced magnetic field. The present study aimed to determine the magnetic susceptibility of sediments collected on the continental shelf near the Santos Basin, southeast of the São Sebastião island (25°57.97’S 45°07.81'W), seeking to identify the possible source area of terrigenous sediments and the flow patterns of siliciclastic sediment yield in the area. It was used particle size analysis and contents of organic matter and calcium carbonate to characterize the sediments, besides paleomagnetism parameters. The analyzed material - core NAP61-1 - was collected using the piston corer sampler in 60 meters water depth, recovering 3.98 meters of sediment core. As from experiments, cyclicity was observed in relative abundance between sand and silt, most likely due to rapid and cyclical variations in the depositional environment. In general, the MS values are low, and show that the sand supply (terrigenous material) has a certain consistency, probably having the same origin. More absolute age is still necessary to establish clearly the events marked here
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A questão agrária é da essência do modo capitalista de produção. A existência ou não do campesinato nesse modo de produção é justamente o cerne da discussão. A questão agrária pode ser interpretada de diferentes formas, por meio de correntes teóricas ou até mesmo paradigmas, como o caso do Paradigma da questão Agrária e o Paradigma do Capitalismo Agrário. Neste trabalho procuro defender a ideia de que a questão agrária é um problema estrutural do capitalismo, atualizada conjunturalmente por diferentes elementos, sejam eles de cunho social, político ou econômico. Um destes elementos, destacado nesta pesquisa, é justamente a luta pela terra em escala nacional e regional. A criação e recriação do campesinato no Brasil tem se dado, principalmente, a partir da luta pela terra, materializada em ocupações, acampamentos e, conseqüente, criação de assentamentos rurais. Em escala nacional, discuto a diminuição das ocupações de terra e de novos acampamentos nos últimos anos, com o intuito de compreender as possíveis causas. Já, em escala regional, no Pontal do Paranapanema-SP, algumas mudanças no que diz respeito à mobilização das famílias semterra e a esporacidade da vida nos acampamentos são apresentadas a fim de colaborar com a discussão sobre a dinâmica, contemporaneidade e perspectiva da luta pela terra
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This work discusses about the effects and methods of control and elimination of the currents transients generated by switching capacitor banks, this currents are called inrush currents. Capacitor banks are widely used to compensate a low power factor generated by the widespread use of inductive loads. Currently many of these banks are automatic and therefore the capacitive cells are connected and disconnected according to the inductive loads on the network. However when connecting a capacitor bank to a bus can generate currents transients generated by electromagnetic transients. Aspects of the network, for example, the existence of a bank already connected to the bus, can influence the intensity of this phenomenon. This paper discusses some characteristics of the capacitors and the network to justify and explain the appearance of these transients and discusses its effects on the network and to other equipment. It is concluded that the main cause of this phenomenon is the voltage difference between the capacitor to be connected to the network and the bus, the results of the study were the bases to discuss the traditional methods to mitigate these currents and therefore its negative effects. Although in this paper is yet developed a method of electronic switching that can greatly reduce these transients
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Esta pesquisa tem como objetivo levantar a literatura sobre economia do meio ambiente e suas linhas de pensamento, para comparar sua aplicabilidade em relação às políticas públicas relacionadas à gestão de resíduos sólidos. No primeiro capítulo são apresentadas as principais correntes da economia do meio ambiente. A seguir, no capitulo segundo, colocamos o Brasil no cenário da problemática ambiental, e então, dos resíduos sólidos, contemplando as legislações vigentes no Estado de São Paulo e no Brasil, além de introduzir o conceito do resíduo sólido. O capítulo final apresenta os resultados país por fontes especializadas nos últimos anos, e a tendência que as políticas públicas poderiam seguir para uma melhor gestão dos resíduos sólidos