977 resultados para ponte viscosità precompressione
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Due to concerns about rational use of energy, several alternative technologies of power generation appeared, including the conversion of solar energy into electrical energy by photovoltaic panels. In low-income households, the refrigerator represents considerable impact on the electric bill, since it requires constant power given its use in food preservation. It is possible to reduce this share, with the use of an alternative energy source. This work presents a timed switching electronic system, which allows commercial equipment that is not affected by short interruptions in the power supply to use a photovoltaic panel as a source of alternative energy, which usually do not provide energy continuously. Switching is made automatically in case of low incidence of sunlight, and without any form of energy storage. Between each switching, there is a dead time without power supply, therefore preventing the use of synchronizers circuits between the photovoltaic panel and the public power grid. A circuit containing a 80C31 microcontroller is used to control the system’s switching. The photovoltaic panel’s voltage inverter is in H bridge configuration, and is also controlled by the microcontroller through Pulse Width Modulation, which makes use of preprogrammed tables to generate the control signals of the power transistors. Through the use of software simulations, the proposed system was tested, which is capable of supplying intermittent single-phase loads. The simulations indicates that the project developed in this paper can be assembled into a prototype and be tested under real operating conditions, as long as the scaling of components, the characteristics of the photovoltaic panel to be used, and the project involved load are taken into account
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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In Brazil there are many cases of cities that suffer from flooding. It often destroys much of the structure of the city, and isolates many families. Relying on emergency measures for these cases and similar cases is of utmost importance. This paper proposes the development of a project of a timber bridge that can be used in emergency situations such as occurs in situations of floods and especially on side roads. It is considered one type of structural bridge which has, among other characteristics, an easy transportation and assembly of the elements. The development is carried out, at this early stage of the project, only about the verification and sizing of structural elements of the superstructure of the bridge. For this purpose, it relies on computer programs, and fundamentally on PCFrame Visual Taco. The first allows you to model the structure and determine the efforts of calculating the elements, and the second one assists at the scaling and the verifications in accordance with the Brazilian technical standards for timber bridges. The wood used in the project comes from the tree Eucalyptus saligna, which is easy to acquaint and manipulate and comes from the region Vale do Paraíba. The bridge in this case of application should have the characteristics mentioned below: short execution time, simplicity of structure and an assembly of a relatively low cost
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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This study analysed the effect of pastes formulated with calcium hydroxide P.A. and different vehicles (saline solution - paste A and Copaifera langsdorffii Desfon oil - paste B) on oral microorganisms and dentin bridge formation in dogs. The antimicrobial action of the pastes and their components was analysed by the minimum inhibitory concentration in agar gel technique. The components were diluted and tested on fifteen standard strains of microorganisms associated with endodontic diseases. The microorganisms were cultivated and after incubation data was analysed using One-Way ANOVA and Turkey's test (P≤0.05). Four superior incisors of ten animals were used to evaluate dentin bridge formation. Two incisors were capped with paste A (GA) and two with paste B (GB). After 90 days, the teeth were extracted for histological analysis and the degree of dentin bridge formation evaluated. Data was analysed by the Kruskal-Wallis test (P<0.05). The pastes and their components were classified in the following decreasing order of antimicrobial action: calcium hydroxide P.A., paste A, paste B and Copaifera langsdorffii Desfon oil. Calcium hydroxide P.A. showed significantly higher antimicrobial action than the pastes or their vehicles. No significant difference was observed between the two pastes in dentin bridge formation. Based on the microorganisms studied, it can be concluded that the pastes analysed showed similar antimicrobial potential but differed significantly from their individual components. No significant difference was observed in dentin bridge formation between the different pastes tested.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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This paper shows the modeling and control of a single-phase full-bridge inverter with high-frequency transformer that may be used as part of a two-stage converter with transformerless DC-DC side or as a single-stage converter (simple DC-AC converter) for grid-connected PV applications. The inverter is modeled in order to obtain a small-signal transfer function used to design the P+Resonant current controller. A highfrequency step-up transformer results in reduced voltage switches and better efficiency compared with converters in which the transformer is used on the DC-DC side. Simulations and experimental results with a 200 W prototype are shown. 1
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Ao iniciarmos nossa atuação numa Secretaria de Educação nos Setores de Psicologia e Psicopedagogia notamos que as práticas enfatizavam avaliação e diagnósticos dos alunos para encaminhamentos médico. Para as escolas da rede, o trabalho da equipe multidisciplinar era uma ponte para os serviços de saúde, bem como representavam o acesso a profissionais que poderiam medicar. Neste sentido, este estudo teve como objetivo refletir, a partir da atuação dos membros das equipes escolares e professores, sobre os entraves nos processos de ensino aprendizagem, buscando, especificamente, descentralizar o foco no aluno e promover um olhar mais amplo para as queixas escolares, que possa contemplar as relações que se estabelecem nas instituições. O estudo baseou-se em uma pesquisa-ação e a análise seguiu a abordagem qualitativa de pesquisa. Por meio de nossas intervenções nas escolas percebemos o quanto os diagnósticos médicos são valorizadas pelos profissionais da educação e como estes são utilizados com justificativas para o fracasso escolar.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Letras - IBILCE
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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This work by questioning the methodology and curriculum standardization and the separation between theory and practice, both of the top training courses for educators and schools in general, proposes to investigate, through action research, writing and analysis of narratives drawn from the author's experiences as a volunteer educator for a Brazilian educational project inspired by the experience of the Portugal's Escola da Ponte, the (trans)formation of educators in educational praxis, ie, the training that is not represented in formatting. Experiences, reflections and analyzes developed are in line to share new possibilities in the training of education professionals to effectively contribute to the methodological and curricular flexibility and with no dissociation between practice and theory present in current and anachronistic higher education courses educators, as well as the vast majority of elementary schools, both public and private and secondary levels