713 resultados para Interphase transformer


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Cet étude et thème de dissertation est devenue nécessaire a partir des inquiétudes d éducateur et des pratiques pédagogiques développées aux classes d éducation physique au tour nocturne à l École Municipale Prof. Veríssimo de Melo, dont les élèves sont des jeunes et adultes que habitent au quartier Felipe Camarão. Ces jeunes cohabitent avec le stigmate de la violence que est toujours présente dans cette communauté, située a la région ouest de Natal. On peut trouvé parmi les élèves y matriculés des trajectoires de vie interrompues par facteurs de risque comme criminalité, des adolescentes enceintes et drogues. Ces faits interférent directement avec les procès d intégration sociale et augmentent la violence, reproduisant les cycles de pauvreté et ainsi, limitant les possibilités d ascension sociale. Les résultats des procédées pédagogiques utilisées pendant les classes ont montré la nécessité d approfondir cet étude problématisant cette réalité et, incitant par les pratiques corporelles et discussion, la réflexion sur des thèmes comme facteurs de risque, temporalité, projets de vie et auto-connaissance. En profitant de l intérêt de ces jeunes pour la langage cinématographique comme une façon de mettre en ouvre ces réflexions et rapportant leur connaissance formel avec le savoir et expériences du groupe on a décidé de produire un film court de 15 minutes sur le quartier, idéalisé et produit collectivement. Pour ça, ont a réalisé 10 classes-ateliers avec les élèves qui ont été connus comme « le groupe du cinéma ». Les ateliers pédagogiques qui sont ici, au même temps, référence de recherche et procédée pédagogique, réaffirment la notion de résilience: la capacité de l individu de transformer un obstacle, une adversité ou même une tragédie personnel dans une situation positive ou comme un renfort de ce que nous avons de meilleur. Dans ce sens, cet étude peut aider les professeurs de toutes les matières, que travaillent a l école publique et que se trouvent dans ce contexte, considéré vulnérable, surtout le professeur d éducation physique. Ce travail peut aussi devenir une référence pour aborder des concepts et valeurs que nos aideront à renouveler cette vision de monde étroite et déterministe, responsable pour la reproduction des cycles de pauvreté et violence. Cet étude a été fondée sur des auteurs comme Edgar Morin, Bóris Cyrulnik et Conceição Almeida parmi d autres

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Cet article propose, à partir d'une analyse de trois expériences différentes de la formation des enseignants, voir la pratique de l'enseignant comme une réalité et la comprendre, dans cette perspective, dynamique, génératrice de contenu et possible d être transformée. Une étude menée par un groupe de chercheurs de Sao Paulo do Potengi / RN avec des enseignants des écoles municipales dans les années 70, la mise en oeuvre du projet de réorientation curriculaire par le Bureau d Éducation de la ville de São Paulo - SP en 1989, et le cours Pédagogie de la Terre à l UFRN créée en 2002 sont pris en compte dans ce travail, comme des références dans la formation des enseignants qui démontrent à la fois les référentiel théorique et les actions développées sur la pertinence des réflexions par rapport à l'enseignement pratique comme point de départ quand on cherche à transformer l'école. Du matériel de lecture sur la manière dont ces processus de formation des événements a été possible de détecter la présence de deux éléments qui semblent être importants: la participation des personnes concernées et le reflet de leurs pratiques. Nous avons cherché à comprendre comment ces éléments apparaissent dans la pratique de deux étudiants du cours de Pédagogie de la Terre au cours de leurs classes de stage, en cherchant à identifier la façon dont ils font avancer ce point de vue de ce qui se passe dans le processus de formation. L'étude fait remarquer que la participation des sujets comme la réflexion collective des pratiques peuvent être cruciale pour la compréhension d'un enseignement qui peut être dynamique et de transformation des sujets, et qu elle peut se passer dans un processus de construction collective du savoir marquée par une refléxion et d une manière critique de faire et réflexive d'elle-même dans l'autonomie scolaire, améliorer la qualité de l'enseignement et le renforcement de l'enseignant et de l'élève comme des sujets actifs dans la reconstruction de leurs connaissances

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Cette étude présente l anthropophagie comme une notion théorique et experiementale du corps qui réhabilite le sensible et réveille le monde perçu. L argumentation fait ressortir la dimension sensible du corps et de la connaissance, en considerant sa sensibilité et motricité, corps qui ne se sépare pas de la nature et de l histoire, en actuant dans le monde comme présence vive, originaire, en mouvement ; en supposant un sujet qui, au même temps que construit ses propres senses, il dépend de l expérience de l autre et du monde, en créant et en recréant la culture, et il agrandit le processus de connaître, de sentir, de penser, d agir, d être, de se transformer. Cette attitude annonce une connaissance sensible et un corps qui est suscetible de sensations, mais d expréssions aussi, de communication, de création, aspects indispensables pour se pensar l éducation comme un space sensible, d apprantissage et réssignification de la culture ; que dévient possible la communion avec le corps, le temps, le space ; qu enseigne à réapprendre à voir le monde, que considère la réversibilité des senses et l esthésie comme champs de l expérience sensible et de l imputation des senses ; qu évoque la beauté des multiples léctures du vécu et qu agrandit la compréhension du soi et de l autre. L objectif de ce travail est comprendre l anthropophagie comme une attitude du corps et de la connaisance sensible, qu approfondit la rélation de l être au monde, la rélation avec l autre et permet la création de senses culturelles, ésthetiques et éxistentielles our l éducation. Nos présentons l attitude phénomologique de Maurice Merleau-Ponty comme référence théorique et méthodologique de notre recherche. Il s agit d une attitude de la pensée qui place la conaissance au centre de nos expériences vécues au monde ; une attitude qui ne propose pas un sens définitif des choses et des personnes et qui contribue pour la compréhension de l anthropophagie, du corps, du sensible, du monde et de l autre, en indiquant des développements de ces réflexions pour l éducation. En créant des horizonts de sense et strastégies de pérception sur l anthopophagie, nos considérons comme choix notre expérience vécu, comme les voyages; atelier d extension avec des élèves du cours de Technologie en Production Culturelle de l Institut Fédéral d Éducation, Science et Technologie du Rio Grande do Norte-IFRN, Campus Cidade Alta ; l anthropophagie comme élement de l Art Moderne Brésilien ; les créations et les récits des élèves ; images ; filmes et livres recherchés ; dialogues avec les penseurs Lévi-Strauss, Montaigne et Oswald de Andrade, qui constituent nos principales références conceptuelles et qui ont permis traversé des savoirs et promouvoir un dialogue entre divers champs de connaissance, comme l Anthropologie, la Philosophie, l Art et l Éducation. Ces stratégies constituent le resultat partiel et inachevé d un processus de connaisance de soi et de l autre, que permet de revivre des mémoires, faire ressortir des couleurs, des senses, des goûts, des découvertes sensibles et encourageantes sur la connaissance, sur l art, des découvertes sur soi même, sur l autre, sur le monde, sur la vie, indiquant que l éducation peut être un processus fort sensible, dans lequel le corps est une présence indispensable, aussi comme le toucher, le créer, les delires, les affections, les encontres et l invention

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The usual programs for load flow calculation were in general developped aiming the simulation of electric energy transmission, subtransmission and distribution systems. However, the mathematical methods and algorithms used by the formulations were based, in majority, just on the characteristics of the transmittion systems, which were the main concern focus of engineers and researchers. Though, the physical characteristics of these systems are quite different from the distribution ones. In the transmission systems, the voltage levels are high and the lines are generally very long. These aspects contribute the capacitive and inductive effects that appear in the system to have a considerable influence in the values of the interest quantities, reason why they should be taken into consideration. Still in the transmission systems, the loads have a macro nature, as for example, cities, neiborhoods, or big industries. These loads are, generally, practically balanced, what reduces the necessity of utilization of three-phase methodology for the load flow calculation. Distribution systems, on the other hand, present different characteristics: the voltage levels are small in comparison to the transmission ones. This almost annul the capacitive effects of the lines. The loads are, in this case, transformers, in whose secondaries are connected small consumers, in a sort of times, mono-phase ones, so that the probability of finding an unbalanced circuit is high. This way, the utilization of three-phase methodologies assumes an important dimension. Besides, equipments like voltage regulators, that use simultaneously the concepts of phase and line voltage in their functioning, need a three-phase methodology, in order to allow the simulation of their real behavior. For the exposed reasons, initially was developped, in the scope of this work, a method for three-phase load flow calculation in order to simulate the steady-state behaviour of distribution systems. Aiming to achieve this goal, the Power Summation Algorithm was used, as a base for developing the three phase method. This algorithm was already widely tested and approved by researchers and engineers in the simulation of radial electric energy distribution systems, mainly for single-phase representation. By our formulation, lines are modeled in three-phase circuits, considering the magnetic coupling between the phases; but the earth effect is considered through the Carson reduction. It s important to point out that, in spite of the loads being normally connected to the transformer s secondaries, was considered the hypothesis of existence of star or delta loads connected to the primary circuit. To perform the simulation of voltage regulators, a new model was utilized, allowing the simulation of various types of configurations, according to their real functioning. Finally, was considered the possibility of representation of switches with current measuring in various points of the feeder. The loads are adjusted during the iteractive process, in order to match the current in each switch, converging to the measured value specified by the input data. In a second stage of the work, sensibility parameters were derived taking as base the described load flow, with the objective of suporting further optimization processes. This parameters are found by calculating of the partial derivatives of a variable in respect to another, in general, voltages, losses and reactive powers. After describing the calculation of the sensibility parameters, the Gradient Method was presented, using these parameters to optimize an objective function, that will be defined for each type of study. The first one refers to the reduction of technical losses in a medium voltage feeder, through the installation of capacitor banks; the second one refers to the problem of correction of voltage profile, through the instalation of capacitor banks or voltage regulators. In case of the losses reduction will be considered, as objective function, the sum of the losses in all the parts of the system. To the correction of the voltage profile, the objective function will be the sum of the square voltage deviations in each node, in respect to the rated voltage. In the end of the work, results of application of the described methods in some feeders are presented, aiming to give insight about their performance and acuity

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This work describes the study, the analysis, the project methodology and the constructive details of a high frequency DC/AC resonant series converter using sequential commutation techniques for the excitation of an inductive coupled thermal plasma torch. The aim of this thesis is to show the new modulation technique potentialities and to present a technological option for the high-frequency electronic power converters development. The resonant converter operates at 50 kW output power under a 400 kHz frequency and it is constituted by inverter cells using ultra-fast IGBT devices. In order to minimize the turn-off losses, the inverter cells operates in a ZVS mode referred by a modified PLL loop that maintains this condition stable, despite the load variations. The sequential pulse gating command strategy used it allows to operate the IGBT devices on its maximum power limits using the derating and destressing current scheme, as well as it propitiates a frequency multiplication of the inverters set. The output converter is connected to a series resonant circuit constituted by the applicator ICTP torch, a compensation capacitor and an impedance matching RF transformer. At the final, are presented the experimental results and the many tests achieved in laboratory as form to validate the proposed new technique

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Equipment maintenance is the major cost factor in industrial plants, it is very important the development of fault predict techniques. Three-phase induction motors are key electrical equipments used in industrial applications mainly because presents low cost and large robustness, however, it isn t protected from other fault types such as shorted winding and broken bars. Several acquisition ways, processing and signal analysis are applied to improve its diagnosis. More efficient techniques use current sensors and its signature analysis. In this dissertation, starting of these sensors, it is to make signal analysis through Park s vector that provides a good visualization capability. Faults data acquisition is an arduous task; in this way, it is developed a methodology for data base construction. Park s transformer is applied into stationary reference for machine modeling of the machine s differential equations solution. Faults detection needs a detailed analysis of variables and its influences that becomes the diagnosis more complex. The tasks of pattern recognition allow that systems are automatically generated, based in patterns and data concepts, in the majority cases undetectable for specialists, helping decision tasks. Classifiers algorithms with diverse learning paradigms: k-Neighborhood, Neural Networks, Decision Trees and Naïves Bayes are used to patterns recognition of machines faults. Multi-classifier systems are used to improve classification errors. It inspected the algorithms homogeneous: Bagging and Boosting and heterogeneous: Vote, Stacking and Stacking C. Results present the effectiveness of constructed model to faults modeling, such as the possibility of using multi-classifiers algorithm on faults classification

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This work presents a theoretical and numerical analysis of structures using frequency selective surfaces applied on patch antennas. The FDTD method is used to determine the time domain reflected fields. Applications of frequency selective surfaces and patch antennas cover a wide area of telecommunications, especially mobile communications, filters and WB antennas. scattering parameters are obteained from Fourier Transformer of transmited and reflected fields in time domain. The PML are used as absorbing boundary condition, allowing the determination of the fields with a small interference of reflections from discretized limit space. Rectangular patches are considered on dielectric layer and fed by microstrip line. Frequency selective surfaces with periodic and quasi-periodic structures are analyzed on both sides of antenna. A literature review of the use of frequency selective surfaces in patch antennas are also performed. Numerical results are also compared with measured results for return loss of analyzed structures. It is also presented suggestions of continuity to this work

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The Electrical Submersible Pump (ESP) has been one of the most appropriate solutions for lifting method in onshore and offshore applications. The typical features for this application are adverse temperature, viscosity fluids and gas environments. The difficulties in equipments maintenance and setup contributing to increasing costs of oil production in deep water, therefore, the optimization through automation can be a excellent approach for decrease costs and failures in subsurface equipment. This work describe a computer simulation related with the artificial lifting method ESP. This tool support the dynamic behavior of ESP approach, considering the source and electric energy transmission model for the motor, the electric motor model (including the thermal calculation), flow tubbing simulation, centrifugal pump behavior simulation with liquid nature effects and reservoir requirements. In addition, there are tri-dimensional animation for each ESP subsytem (transformer, motor, pump, seal, gas separator, command unit). This computer simulation propose a improvement for monitoring oil wells for maximization of well production. Currenty, the proprietaries simulators are based on specific equipments manufactures. Therefore, it is not possible simulation equipments of another manufactures. In the propose approach there are support for diverse kinds of manufactures equipments

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This work aims to predict the total maximum demand of a transformer that will be used in power systems to attend a Multiple Unit Consumption (MUC) in design. In 1987, COSERN noted that calculation of maximum total demand for a building should be different from that which defines the scaling of the input protection extension in order to not overestimate the power of the transformer. Since then there have been many changes, both in consumption habits of the population, as in electrical appliances, so that this work will endeavor to improve the estimation of peak demand. For the survey, data were collected for identification and electrical projects in different MUCs located in Natal. In some of them, measurements were made of demand for 7 consecutive days and adjusted for an integration interval of 30 minutes. The estimation of the maximum demand was made through mathematical models that calculate the desired response from a set of information previously known of MUCs. The models tested were simple linear regressions, multiple linear regressions and artificial neural networks. The various calculated results over the study were compared, and ultimately, the best answer found was put into comparison with the previously proposed model

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The modern society depends on an efficient communications system able to of transmitting and receiving information with a higher speed and reliability every time. The need for ever more efficient devices raises optimization techniques of microstrip devices, such as techniques to increase bandwidth: thicker substrates and substrate structures with EBG (Electromagnetic Band Gap) and PBG (Photonic Band Gap). This work has how aims the study of the application of PBG materials on substrates of planar structures in microstrip, more precisely in directional quadrature couplers and in rat-race and impedance of transformers. A study of the planar structures in microstrip and substrates EBG is presented. The PBG substrates can be used to optimize the radiation through the air, thus reducing the occurrence of surface waves and the resulting diffraction edge responsible for degradation of radiation pattern. Through specific programs in FORTRAN Power Station obtained the frequencies and couplings for each structure. Are used the program PACMO - Computer Aided Design in Microwave. Results are obtained of the frequency and coupling devices, ranging the frequency band used (cellular communication and Wimax systems) and the permittivity of the substrate, comparing the results of conventional material and PBG materials in the s and p polarizations.

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This work discusses the design of a transformer used in a plant plasma. This plant, which is being developed in UFRN, will be used in the treatment of waste. It consists basically of a radio frequency power supply and a inductive plasma torch. The transformer operates at the nominal frequency of 400 kHz, with 50 kW, allowing the adaptation of impedance between the power supply and torch. To develop the project, a study was done on the fabrication technologies and physical effects on the frequency of operation. This was followed by the modeling of this transformer. Finally, simulations and tests were conducted to validate the design

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Naphthenic lubricating oils are used in transformers with the purpose of promoting electrical insulation and dissipating heat. The working temperature range of these oils typically lies between 60°C and 90°C and their useful life is 40 years in average. In that temperature range, the oils are decomposed during operation, whereby a small fraction of polar compounds are formed. The presence of these compounds may induce failure and loss of physical, chemical and electrical properties of the oil, thus impairing the transformer operation. By removing these contaminants, one allows the oxidized insulating oil to be reused without damaging the equipment. In view of this, an investigation on the use of surfactants and microemulsions as extracting agents, and modified diatomite as adsorbent, has been proprosed in this work aiming to remove polar substances detected in oxidized transformer oils. The extraction was carried out by a simple-contact technique at room temperature. The system under examination was stirred for about 10 minutes, after which it was allowed to settle at 25°C until complete phase separation. In another experimental approach, adsorption equilibrium data were obtained by using a batch system operating at temperatures of 60, 80 and 100°C. Analytical techniques involving determination of the Total Acidity Number (TAN) and infrared spectrophotometry have been employed when monitoring the decomposition and recovery processes of the oils. The acquired results indicated that the microemulsion extraction system comprising Triton® X114 as surfactant proved to be more effective in removing polar compounds, with a decrease in TAN index from 0.19 to 0.01 mg KOH/g, which is consistent with the limits established for new transformer oils (maximal TAN = 0.03 mg KOH/g). In the adsorption studies, the best adsorption capacity values were as high as 0.1606 meq.g/g during conventional adsoprtion procedures using natural bauxite, and as high as 0.016 meq.g/g for the system diatomite/Tensiofix® 8426. Comparatively in this case, a negative effect could be observed on the adsorption phenomenon due to microemulsion impregnation on the surface of the diatomite

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Les initiatives du gouvernement ayant pour finalité une réorganisation de la structure urbaine de la ville au début du XXème siècle reflètent le désir vécu par les membres de l'élite locale d'encadrer Natal dans les moules des grands centres urbains de la même période. Les élites désiraient transformer Natal dans une ville moderne. Dans ce but, le gouvernement s'est engagé dans la reformulation de quelques espaces physiques de la ville. Néanmoins, il fallait aussi d autres que les transformations urbaines, la ville devrait passer par des réformes sociales. De cette façon, ces groupes ont créées des nouvelles institutions et espaces de sociabilité qui affirmeraient la capitale de l'État comme une ville moderne. Les institutions formelles avaient un rôle imortant dans la construction de cette nouvelle ville convoitée par l'élite locale. Ainsi, à travers celles-ci, se diffusaient des nouvelles pratiques sociales qui seraient reflétées dans les espaces urbains. Dans des places tels, des cafés, des clubs et associations sportives, l'élite se distinguait du populaire. Dans ces places, leurs pratiques étaient légitimées, en contrepoint avec les pratiques populaires. C était dans les clubs et par les activités pratiquées par leurs membres que les idéals de l'élite circulaient, c était par là que l'élite se formait et se transformait. De cette façon, les aspirations d'un groupe social reflétaient dans l'organisation sociale des espaces de la ville

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The paper describes a novel neural model to electrical load forecasting in transformers. The network acts as identifier of structural features to forecast process. So that output parameters can be estimated and generalized from an input parameter set. The model was trained and assessed through load data extracted from a Brazilian Electric Utility taking into account time, current, tension, active power in the three phases of the system. The results obtained in the simulations show that the developed technique can be used as an alternative tool to become more appropriate for planning of electric power systems.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)