999 resultados para Resistências elétricas
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Pós-graduação em Psicologia - FCLAS
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The contamination of the physical environment occurs as a result of the lack of planning and inadequate management of hazardous products. Due to the difficulty of the characterization and study of soil and groundwater, the contamination has been long neglected. The characterization of these areas by research techniques through direct methods such as physical and chemical analysis, are widely used in the diagnosis and monitoring. However, despite presenting quantitative results, this method is not representative in spatial terms. The purpose of this work is to bring geophysical complementation with the diagnosis, bringing the spatial element for the detection of the contamination plume. In the study area, there was a railway accident in 1999 in which three wagons fell and spilled 240,000 L of diesel onto the soil. The main objective is to assess the presence of contaminants in the residual phase and dissolved in the subsurface, using the technique of Electrical Tomography (ETR), understand the effects of natural attenuation process in the degradation of hydrocarbons and changes in electrical properties in soil and groundwater. The results allowed the definition of three distinct patterns of resistivity region with presence of dissolved phase, set in a historical chemical analyzes: low values (> 60Ω.m) associated with the presence of hydrocarbons in an advanced stage of degradation, intermediate values (260Ω.me 511Ω .m) indicative of coexistence of residual hydrocarbons and dissolved phase, and high values (> 1000Ω.m), which reveal the prevalence of residual phase with incipient degradation, possibly in high toxicity concentrations for effective action of biodegradation processes. The diagnostic of areas with potential accumulation of residual phase can subsidize the planning of remediation techniques and promote the complete decontamination of the area
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Eletronicalceramics are used in many applications such as: multilayer capacitor, transducer, pyroelectric sensors and electrooptic devices. In recent years there has been a growing demand for eletronicalceramics with better performance and functionality. This demand has accelerated the development of synthesis techniques to produce powders with well-defined particle size, shape and crystallinity. The eletronicalceramics in the form of bulk are determined by their performance characteristics of the powders used and the preparation process. So, physical and chemical properties of powders, such as chemical control of stoichiometry, purity, homogeneity, particle size and shape should be observed when choosing the methods of synthesis. Among the techniques used so far, the polymeric precursor method, also known as Pechini, has been considered ideal for the preparation of nanosized powders. Thus, this research project aims to use the polymeric precursor method to prepare powders of lithium tantalate and lanthanum tantalate, with good chemical stability. In this aspect is proposed to investigate the effects of variation of the concentration of europium about the properties of tantalate because doping with Eu3 + indicates that they may occupy different sites in the crystal structure, as in the case of LiTaO3. Effects of things like occupation sites, stability of phases and formation temperature have been previously investigated by the group, which motivated the formulation of this project. Our proposal aims to introduce the Eu3 + LaTaO4 and LiTaO3 and study the structural and optical properties of the powders obtained by Pechini method, as well as correlate these studies with the electrical properties of the material, mainly the Ironelectricty Hysteresis.
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There is no vaccine available against leishmaniasis. Drug resistance, variable efficacy, toxicity, parenteral administration, and requirement for long courses of administration are the main drawbacks of current leishmanicidal drugs. Infections by protozoans of the genus Leishmania are the major worldwide health problem, with high endemicity in developing countries. The drugs of choice for the treatment of leishmaniasis are the pentavalent antimonials, which exert renal and cardiac toxicity, thus, there is a strong need for safer and more effective treatments against leishmaniasis.
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Pós-graduação em Engenharia Elétrica - FEIS
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The central focus of this paper is to establish that the Brazilian Education Programa to prepare professionals in Technical-Agricultural Schools is suffering a kind of marginalization which comes from two distinct perspectives: the intention to prepare professionals (being a branch of Technical Education) and the relationship to the countryside (a community space historically seen as peripheral in its relation to urban culture). The paper discusses – from a historical and sociological point of view and using Oral History as methodological approach – the experiences of Math’s teachers in their daily struggles against some conceptions of other teachers (mainly those of technical areas) and against all the “regular” schooling system.
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This paper presents the development and the main results for an interleaved boost rectifier operating as a special input power stage for a trolleybus type vehicle, allowing its feeding by alternate current (AC) or direct current (DC) distribution power systems. When feeding with two wires (single phase) alternate current distribution system, the converter accomplish active power factor correction, providing a relatively sinusoidal current with low total harmonic distortion (THD) and fully complying with IEC 61000-3-4 standards. In addition, a management control system promotes the required automatic operation changes for the proposed rectifier when the vehicle is changing from the DC distribution power system to the AC distribution power system and vice-versa, keeping its original electrical DC system characteristics for the adjustable speed driver sub-system. The main experimental results for a prototype rated at 150kW are presented, considering its application for a trolleybus with DC adjustable speed driver, demonstrating the proposed converter benefits and the possibility of AC feeding system for trolleybus type vehicle.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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This paper presents some results of the investigation on the Mathematical Education Centre (CEM), a group of mathematics teachers’ educators in São Paulo, Brazil, acting mainly between 1984 and 1997. The essay, marked by an effort to constitute the identity of the CEM based on Foucault, assumes that the identity constitution process is not about what CEM is or was, but mainly about a set of possibilities of apprehending it from its historically contextualized strategies and initiatives. In this Foucauldian reading, which brings about concepts such as "strategic device", "resistance" and "power relations", the CEM constitution appears while it creates conditions for the constitution of Brazilian modern mathematical education.
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Um conjunto de depoimentos coletados oralmente e de fontes escritas disponíveis no arquivo inativo de um antigo Grupo Escolar paulista é analisado em paralelo à literatura sobre o Movimento Escolanovista visando a compreender os modos como um ideário se impõe, no cotidiano das práticas escolares, num ritmo constante de avanços e resistências, alterações e manutenções. Ao mesmo tempo, defende-se que o Movimento Escolanovista – ou qualquer proposta educacional – não é um bloco maciço de significados fixos, mas uma leitura, uma mobilização, uma apropriação que, segundo os vários significados a ele atribuídos, implica a efetivação de algumas práticas no interior da escola.
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Saudada como consequência de um complexo processo de evolução do arcabouço jurídico-institucional brasileiro, a Lei Federal 12.527, denominada Lei de Acesso a Informações, sancionada em 18 de novembro de 2011 e regulamentada no âmbito do Poder Executivo federal pelo Decreto 7.724, de 16 de maio de 2012, atende o pressuposto do direito à informação fixado pela Constituição Federal de 1988. Valores e práticas historicamente construídos podem significar obstáculos e resistências importantes à sua aplicação. Características do próprio texto legal, que vêm à tona quando comparado aos seus congêneres internacionais, também sinalizam possíveis complicadores. Este artigo indica limites que a Lei de Acesso a Informações pode enfrentar à sua consolidação, originários principalmente do campo da cultura político-institucional, que se tornam mais nítidos com o exame de características brasileiras em comparação com outros países que possuem dispositivos semelhantes.
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The purpose of this essay is to reflect on the quality of the school and psychosocial aspects involved in the assimilation of educational innovations by teachers in their teaching practices.Innovations cause resistance which endanger the goals of improving education outcomes. This makes the possibilities of basic schooling fail, preventing contribute to the transformation of living conditions of the working classes.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)