Resumo: Esse trabalho foi realizado com o objetivo de comparar o desempenho de um trator equipado com pneus diagonais novos e pneus diagonais desgastados, em três condições de superfície: pista com solo mobilizado, pista com cobertura vegetal e pista com solo firme. Foi utilizado o delineamento experimental em faixas, sendo que em cada faixa (pista) foram dispostos os tratamentos em blocos ao acaso, com um arranjo fatorial de 2x4, definidos pelos dois conjuntos de pneus diagonais (novos e desgastados) e quatro condições de deslocamento, distinguidas pela mudança de marcha do trator, totalizando oito tratamentos, com três repetições cada, perfazendo 72 unidades experimentais. Foram coletados os dados para o cálculo da velocidade de deslocamento, patinagem das rodas traseiras e dianteiras do trator e consumo horário de combustível. Também foram coletados os dados de força de tração, sendo calculada a potência disponível na barra de tração em função da velocidade de deslocamento. Foi utilizado como carro dinamométrico a Unidade Móvel de Ensaio na Barra de Tração - UMEB, pertencente ao Núcleo de Ensaios de Máquinas e Pneus Agroflorestais - NEMPA, do Departamento de Engenharia Rural da Faculdade de Ciências Agronômicas - FCA da UNESP, Campus de Botucatu - SP. Os resultados mostraram que tanto as condições dos pneus quanto as condições do solo interferiram na capacidade do trator em desenvolver força de tração, sendo o 2 pior desempenho obtido na pista com solo mobilizado. O melhor desempenho do trator foi na pista com solo firme; porém, na pista com cobertura vegetal ocorreram as melhores condições de força de tração do trator em relação ao solo mobilizado, mostrando que a presença da cobertura vegetal entre o rodado e o solo interferiu diretamente na relação rodado/solo. Na pista com solo mobilizado os resultados mostraram que a velocidade foi a menor... (Resumo completo, clicar acesso eletrôncio abaixo) / Abstract: The objective of this work was to compare the performance of a tractor equipped with used and new bias-ply tires, operating in three surface conditions: tillage soil, vegetal covered soil and firm soil. The experimental design were tracks and, in each track, treatments were disposed in blocks to the chance in a 2x4 factorial arrangement, defined by the two groups of tires (used and new bias-ply) and four speed conditions, distinguished by tractor’s gear change, totaling eight treatments, with three repetitions each, completing 72 experimental units. There were collected data to calculate: speed, front and rear tires slippage and fuel consumption. There were also collected data of traction strength to calculate available power at traction bar versus speed. The dynamometric car used was the Mobile Drawbar Test Unit - UMEB, owned by the Facility of Agricultural and Forestry Tires and Machines Assays (NEMPA) of Rural Engineering Department in the Agronomics Science College - FCA, UNESP, Botucatu campus. Results showed that both, tires and soil conditions, changed tractor capacity on developing traction strength. The worst performance was observed on the tillage soil. On the track with soil covered with vegetal residues, occurred better tractor traction strength conditions than on track with tillage soil, showing the presence of vegetal cover between tire and soil interfered directly on the tires/soil relation ship. 4 On the track with tillage soil, results showed that the forward speed was the lowest among the three soil conditions due to the front and rear tires slippage which is higher than vegetal covered and firm soil tracks. Fuel consumption results showed higher values on tilled tracks when comparing with firm and vegetal covered tracks. Data of available power at the drawbar were statistically equal on tilled and vegetal-covered soil tracks... (Complete abstract click electronic access below) / Orientador: Kléber Pereira Lanças / Coorientador: Antonio Gabriel Filho / Banca: Ulisses Rocha Antuniassi / Banca: Alberto Kazushi Nagaoka / Mestre

Orientador: Kleber Pereira Lanças / Banca: João Alberto Borges de Araujo / Banca: João Eduardo Guarnetti Santos / Banca: Arno Udo Dallmeyer / Banca: Ila Maria Correa / Resumo: As transmissões dos tratores agrícolas transferem energia do motor para as rodas motrizes, e o torque disponível nos rodados é convertido em tração bruta, que é responsável por vencer a resistência ao rolamento do trator e pela tração disponível (líquida) na barra de tração do trator. Este trabalho teve por objetivo desenvolver um sistema eletromecânico para determinação do torque no eixo das rodas motrizes de tratores agrícolas, denominado torsiômetro, e validá-lo através de ensaios de tração com auxílio de um carro dinamométrico equipado com instrumentação eletrônica para aquisição de dados. A pesquisa foi conduzida no Núcleo de Ensaios de Máquinas e Pneus Agroflorestais (NEMPA) da Faculdade de Ciências Agronômicas (FCA/UNESP), Botucatu-SP. O protótipo foi concebido utilizando programas computacionais específicos para projeto mecânico, e construído para ser instalado no eixo traseiro de tratores agrícolas de até 90 kW. O torsiômetro foi confeccionado com estrutura metálica, apta a resistir a grandes demandas de torque, podendo ser adaptado a qualquer outro trator com características similares, de igual ou menor potência. O dispositivo baseia-se em um braço de alavanca (momento torsor), onde obtém-se os valores de força com uma célula de carga e os valores de torque por uma equação matemática. Após a conclusão do projeto e construção do protótipo, foram realizadas avaliações funcionais e de resistência, e em seguida realizaram-se ensaios de tração em pista, para sua validação. Nos ensaios em pista, foram realizadas as avaliações em duas superfícies (concreto e solo firme), três marchas, oito cargas na barra de tração e com a tração dianteira auxiliar (TDA) ligada e desligada. Os resultados obtidos para validar o equipamento foram analisados estatisticamente através de equações de regressão, com destaque ... / Abstract: The transmissions of agricultural tractors transfer the engine power to the drive wheels and the torque, available in the rotated, is converted into gross traction, which is responsible for overcoming the rolling resistance of the tractor and for the net traction on the drawbar. Based on these premises, this research aims to develop an electromechanical system, which we designate "torque meter" or "torque transducer", to determine the torque and power on the axle of the driving wheels in agricultural tractors, and validate it through traction tests, with the support of a dynamometer car, and electronic instrumentation for data acquisition. The work was conducted at the Agro Forestry Machine and Tire Testing Center (NEMPA) at the College of Agronomic Sciences, São Paulo State University (FCA/UNESP), Botucatu-SP, Brazil. The torque meter was developed using specific software for mechanical design, and was built to be installed on rear axle of tractors of up to 90kW. The equipment was made with robust metal structure, able to withstand high demands of torque, and possible to be adapted to any tractor with similar features with equal or less power, simply by meeting the dimensional peculiarities of each model. The torque meter is based on a lever arm (torsional moment) from which it is obtained the strength values with a load cell and the torque values using a mathematical equation. After completion of the development and construction of the prototype, the functional and resistance evaluations were conducted and followed by dynamic tests for the validation of the torque meter. During traction tests, it was performed evaluations on two surfaces (concrete and firm soil), three gears, up to eight drawbar pull and evaluations with the wheel assist drive on and off. The results for the validation of the equipment were statistically analyzed using regression equations, highlighting the linearity ... / Doutor

Calcific aortic valvular disease (CAVD) is the most common valvular pathology in the developed world. CAVD results in calcifications forming on the aortic valve leaflets, inhibiting proper closure and causing complications of stenosis and regurgitation. Although, the mechanisms behind the disease initiation are unknown, it is believed to be a cell-mediated phenomenon, and not the result of passive degradation of the valve as once believed due to the increased prevalence with age. Currently, there are no pharmaceutical options for the prevention or reversal of calcifications, the only treatment option is complete valve replacement, an imperfect solution. Hindering the development of potential therapeutics is that currently there are no adequate animal models which replicate the calcification and cell death seen in disease explanted valves. An in vitro model has been develop where valvular interstitial cells (VICs), the main cell type of the valve, are seeded at high density into tissue culture polystyrene dishes and cultured with TGF-β1. This results in VICs activating to the myofibroblast phenotype and forming cell aggregates. Due to currently unknown mechanisms, apoptosis occurs within the center of the aggregates and calcification ensues. Although simplistic, this model has been used to show that rate and frequency of aggregation is affected by cellular tension; conditions of high tension increase aggregation response, while conditions of low tension prevent aggregation and calcification from occurring. It is important to note; however, that despite its wide usage, the current model is limited as the aggregation and subsequent calcification are random occurrences and are not consistent across literature where same conditions for control samples are used. The motivation of the presented work is two-fold. First, high intracellular tension has been suggested as one of the mechanisms leading to disease in the valve. Despite the clear and important role of cell tension, VIC tension has never before been measured in a dynamic environment. The ways in which dynamic stimulation affects individual VIC tension is not known. In aim one, a method is developed to allow for long-term cyclic stretch of VICs with measurement of cell traction force. It was found that cyclic stretch decreased cell tension in cells with high prestress and increased cell tension for conditions of low prestress. Combined, these findings indicate a homeostatic cellular tension which is dependent upon the mechanical environment. In the second aim, a novel method for creating VIC aggregates is validated. Micro-contact printing, essentially “stampingâ€� of a protein in a defined pattern, is used to create circular aggregates on polyacrylamide gels. This method allows for the separation of the aggregation from the subsequent calcification, an improvement over the current in vitro model. The method is then used to explore the role of the distribution of tension in the initiation of disease

O desenvolvimento de novos recursos terapêuticos capazes de acelerar o processo de reparo tem proporcionado avanços significativos no tratamento de lesões tendinosas. O objetivo do presente estudo foi analisar a influência da radiação LASER HeNe em cicatrização de tendões. Foi desenvolvido um modelo experimental de lesão de tendão de Aquiles através de um procedimento minimamente invasivo em coelhos adultos. Foram utilizados 40 animais distribuídos em quatro grupos de 10 animais (I, II III IV). No grupo I a lesão do tendão foi unilateral (pata direita) e o tendão lesado não recebeu estímulos com LASER. No grupo II a lesão foi unilateral (pata direita) e o tendão lesado recebeu estímulos com LASER. No grupo III a lesão do tendão foi bilateral e apenas a pata direita foi estimulada com LASER. No grupo IV foi realizada \"Sham Operation\" bilateralmente e apenas o tendão da pata direita recebeu estímulo com LASER. Todos os animais foram tratados com dose a 5 J/cm2 de forma pontual com contato direto durante 8 dias consecutivos, diariamente. Após este período os animais foram sacrificados e os tendões de Aquiles submetidos a ensaios mecânicos de tração em máquina de ensaio mecânico. Foram ensaiados 71 tendões, sendo 09 descartados. Embora não tenhamos observado diferença estatística significante nas comparações feitas entre os grupos, podemos notar que existiu uma tendência apontando que os tendões estimulados com LASER apresentaram resistência menor que os grupos controles. Estes resultados sugerem que o LASER diminuiu a resistência dentro das condições estudadas. Relevância Clínica: O presente trabalho mostra o conceito de que a irradiação LASER pode diminuir a resistência mecânica da cicatrização tendinosa em fases precoces do processo. / The development of new therapeutic resources addressing accelerating the repairing process has proportioned a meaningful advance in the treatment of tendon lesions. The purpose of the present study was to analyse the influence of He-Ne LASER radiation on tendon healing. An experimental model of Achilles tendon lesion was developed through a minimally invasive procedure in adults rabbits. We used 40 animals divided in groups of 10 animals each. In group I the tendon lesion was unilateral (right-paw) and the injured tendon did not receive LASER stimulation. In group II the lesion was unilateral (right-paw) and only, the injured side received LASER stimulation. In group III the tendon lesion was bilateral and only the right-paw was stimulated by LASER. In group IV bilateral sham operation was performed and only the right - paw received LASER stimulation. All the animals were treated with 5 J/cm2 dosis in a punctual way with direct contact for 8 successive days. After this period the animals were killed and the Achilles tendons were submitted to mechanical tests in traction on a mechanical testing machine. Seventy-one tendons were tested and 9 were discarded. No statiscally significant difference was observed in the comparison done between groups, however we could notice a tendency suggesting that the tendons stimulated by LASER presented a lesser mechanical resistance. These results suggest that LASER probably reduces the resistance in the studied conditions. Clinic Relevance: The present study supports the concept that LASER irradiation may induce an attenuation of the mechanical properties of the healing tendon in a very early phasis of the proccess.

O objetivo deste estudo foi avaliar, através de ensaios de tração, os efeitos do desenvolvimento de miopatia metabólica secundária a administração de corticosteróide sobre propriedades biomecânicas dos músculos diafragma e gastrocnêmio medial de coelhos. Foram estudadas 30 coelhas albinas adultas da raça Nova Zelândia, divididas em dois grupos de 15: Grupo Experimental (GE), que recebeu injeções subcutâneas de succinato sódico de 21 metil-prednisolona (Solumedrol Ò; Pharmacia - Up John N.N. / S.A. – Puurs - Bélgica) nas doses de 2 mg/kg/dia, e Grupo Controle (GC) que recebeu soro fisiológico a 0,9% por via subcutânea em volumes proporcionais. Ambos os grupos foram tratados durante 21 dias consecutivos. Os ensaios de tração foram realizados utilizando uma Máquina Universal de Ensaios do Laboratório de Bioengenharia da Faculdade de Medicina de Ribeirão Preto - USP. Para o hemi-diafragma esquerdo foram feitos 24 ensaios, 12 para o GE e 12 para o GC e excluídos 3 animais de cada grupo devido a problemas técnicos. Para o gastrocnêmio medial esquerdo foram feitos 30 ensaios, sendo 15 no GE e 15 no GC. A análise histoenzimológica dos músculos hemi-diafragma e gastrocnêmio medial direitos foi feita em 3 coelhos do GE e 3 do GC. O peso médio final dos animais no GE foi 3,6 Kg e no GC 4,0 Kg. A variação média percentual de peso final no GE foi - 8,4% e no GC 3,1%. O valor médio de peso final do gastrocnêmio no GE foi 5,6g e no GC 7,0g. Os valores médios de área, largura e espessura do gastrocnêmio no GE foram 2,4 x 10-4 m 2, 21,7 mm e 5,4 mm, respectivamente e no GC 2,8 x 10-4 m 2, 24,1 mm e 6,7.mm Nos diafragmas os valores médios de tensão e deformação do limite máximo, tensão e deformação do limite de proporcionalidade e módulo de elasticidade no GE comparado ao GC utilizando o teste t de Student e teste de Mann Whitney, não mostraram diferenças estatísticamente significantes. Nos gastrocnêmios os valores médios de carga máxima, carga e deformação do limite de proporcionalidade e rigidez no GE comparado ao GC, pelo teste t de Student não mostraram diferença estatística significante. Porém, o valor médio de deformação máxima no GE foi 26,63 x10-3 m e no GC 32,33 x10-3 m, mostrando significância estatística entre os grupos através do teste t de Student. Quanto aos locais de ruptura, no GE, 9 foram no ventre muscular, 2 na porção miotendínea distal e 4 na origem e no GC 8 ocorreram no ventre muscular, 5 na porção miotendínea distal e 2 na origem. Do ponto de vista histopatológico observamos que: a miopatia metabólica apresentou-se mais evidente nos diafragmas do GE; houve alterações metabólicas leves nos gastrocnêmios do GE e ocorreu aumento da succinato de desidrogenase (SDH) e Tricrômicro de Gomori modificado nos diafragmas do GC. Diante disto, concluímos que: 1) Os diafragmas não mostraram alterações de suas propriedade biomecânicas, nas fases plástica e elástica, apresentando a mesma capacidade de alongamento em ambos os grupos, suportando cargas semelhantes; 2) O músculo gastrocnêmio medial manteve suas características e capacidade de alongamento na fase elástica. Entretanto, o tratamento com esteróide, na fase plástica, levou a uma significativa redução do seu limite máximo de deformação, apresentando uma menor capacidade de alongamento, embora com mesma carga máxima do controle. / The aim of this study was to assess, using traction assays, the effects of the metabolic myopathy secondary to corticosteroids on biomechanical features of the diaphragm and the medial gastrocnemius muscles of rabbits. The study was composed of 30 albino adult rabbits of the New Zealand breed, which were divided into 2 groups of 15: Experimental Group (EG), which received subcutaneous injections of sodium succinate of 21 methil-prednisolone with doses of 2mg/Kg/day, and the Control Group (CG) which received subcutaneous Saline in proportional volumes. Both groups were treated during 21 consecutive days. The traction assays were performed by applying the Universal Machine of Assays from the Bioengenering Laboratory at the Medical School of Ribeirão Preto - USP. For the left hemi-diaphragm, 24 assays were performed, 12 for EG and 12 CG. Three animals from each group were excluded due to technical problems. For the left medial gastrocnemius, 30 assays were done, 15 for the EG and 15 for CG. The histoenzymologic analysis of both the hemi-diaphragm muscles and the right mild gastrocnemius were performed in three rabbits of the EG, and 3 of the CG. The final average weight for the animals in EG was 3,6Kg, and in the CG was 4,0Kg. The average percentage variation from the initial to the final weight for the EG was -8,4% and for the CG 3,1%. The final average weight of gastrocnemius was 5,1g in the EG and 7,0g in the CG. The average value of the area width and thickness of the EG was 2,4 x 10 -4 m 2, 21,7 mm and 5,4 mm, respectively, and for the CG 2,8 x 10-4 m 2, 24,1 mm and 6,7mm. In the diaphragms, the average values of the tension and deformity in the maximum threshold, tension and deformity at the proportional threshold and elasticity module in the EG compared to the CG, through the Student t Test and the Mann Whitney test, presented no significant statistical differences. In the gastrocnemius, average values of the maximum load, load and deformity within the threshold of proportions and stiffness in the EG compared to the CG, according to the Student t test, did not present a significant statistical difference. However, the average values of maximum deformity were 26,63 x10 -3 m in the EG and 32,33 x10-3 m in the GC, showing statistical significant difference between groups. Concerning the locations of the rupture in the EG, 9 were in the muscle belly, 2 in the miotendinous distal junction, and 4 in the origin; in the CG the rupture ocurred 8 times in the muscle belly , 5 in miotendinous distal junction and 2 in the origin. From a histopathological view, we have observed that metabolic myophaty was presented clearly evident in the diaphragms of the EG; there were slight metabolic alterations in the gastrocnemius of the EG, and there was an increase of the succinic dehydrogenase (SDH) and modified Gomori Trichrome in the diaphragms of the CG. In this manner, we conclude that: 1) The diaphragms didn´t show alterations of their biomechanical properties, in elastic and plastic phases, showing the same elongation capacity in both groups, with equal loads; 2) The medium gastrocnemius muscles, kept their biomechanical features and elongation capacity in elastic phase. However, the steroid treatment lead to a significant decrease of the elongation capacity in the plastic phase, with maximal loads similar to the control group; 3) It was not found a relationship between histological evidences of metabolic miopathy and changes in the biomechanical properties of the studied muscles.

Les tubes à paroi mince en alliage à mémoire de forme Nickel-Titane (AMF NiTi) sont largement utilisés dans la fabrication de stents auto-expansibles. Leur fonctionnement repose sur la superélasticité (SE), comme de nombreuses autres applications des AMF NiTi dans le domaine biomédical. Le SE est un phénomène cristallographique réversible qui donne aux AMF la capacité de récupérer de grandes déformations par simple déchargement mécanique. En raison de la nature cristallographique du SE, les propriétés mécaniques liées à cet effet devraient être affectées par l'anisotropie inhérente du tube, qui émerge de son processus de fabrication. Cependant, le NiTi est encore souvent considéré comme isotrope dans la conception et l'optimisation de tels dispositifs. L'une des difficultés empêchant l'utilisation de modèles anisotropes est l'absence de caractérisations mécanique de l'anisotropie du tube NiTi. Le présent travail vise à effectuer une telle caractérisation pour un tube superélastique NiTi à paroi mince. Dans une campagne expérimentale, le comportement en traction du tube est analysé à différentes orientations et températures. La technique de corrélation d'image numérique (digital image correlation - DIC) est utilisée pour surveiller la distribution des déformations pendant les essais de traction. Les résultats montrent que toutes les propriétés analysées liées à la SE sont anisotropes. Toutes les dépendances d'orientation sont presque symétriques à 45° de l'axe du tube. Certaines propriétés dépendent également de la température, dépendance qui est également anisotrope. Une approche thermodynamique basée sur l'énergie libre de Gibbs est utilisée pour analyser ces dépendances d'orientation et de température. Avec cette analyse, il a été possible de relier l'hystérésis mécanique de la SE et les contributions irréversibles présentes dans le système. Enfin, l'influence de l'anisotropie sur la distribution des déformations est vérifiée. L'accent est mis sur l'analyse du phénomène de localisation de la déformation tout au long du chargement et du déchargement. L'inclinaison de la bande de localisation est caractérisée et évaluée avec une approche de plasticité. L'angle de la bande avant observé avec DIC est prédit en utilisant des données de vitesse de déformation globale. / Thin walled tubes of Nickel-Titanium shape memory alloys (NiTi SMA) are widely used in the fabrication of self-expandable stents. The operation of stents relies on the superelastic effect (SE), as many other applications of NiTi SMA in the biomedical field. The SE is a reversible crystallographic phenomenon that gives SMA the ability to recover large strains through simple unload. Due to the crystallographic nature of the SE, the mechanical properties related to this effect are expected to be affected by the inherent anisotropy of the tube, which emerges from its fabrication process. However, NiTi is still often treated as isotropic in the design and optimization of such devices. One of the difficulties preventing the use of anisotropic models is a lack of mechanical characterizations about the NiTi tube's anisotropy. The present work aims to perform such characterization for a thin walled NiTi superelastic tube. In an experimental campaign, the tensile behaviour of the tube is analysed at different orientations and temperatures. Digital Image Correlation (DIC) technique is used to monitor the strain distribution during tensile tests. Results show that all the analysed properties related with SE are anisotropic. All the orientation dependencies are nearly symmetrical to 45° from the tube's axis. Some properties are also dependent on temperature, a dependence that is also anisotropic. A thermodynamic approach based on the Gibbs free energy is used to analyse these orientation and temperature dependencies. With this analysis it was possible to relate the SE stress hysteresis and thermodynamic irreversible energy contributions. Finally, the influence of anisotropy on the strain distribution of tensile samples is verified. Focus is given to the analysis of the strain localization phenomenon throughout loading and unloading. The inclination of the localization front band is characterized and evaluated with a plasticity approach. The front angle observed with DIC is predicted using global strain rate data.

O presente trabalho traz o estudo da simulação do desempenho (simulação de marcha) de uma composição ferroviária acionada através de inversores de tensão e motores de indução e alimentada em corrente contínua, um tipo de material rodante recentemente introduzido no Brasil. Tal fato faz com que seja necessário o desenvolvimento de métodos de análise das características deste tipo de material, objetivo maior deste trabalho. A metodologia de análise aqui desenvolvida tem como base a teoria da tração elétrica para o equacionamento da dinâmica do movimento, a teoria do controle do motor de indução e a teoria do funcionamento do próprio motor de indução para a obtenção da corrente captada por esta composição - um dos principais resultados obtidos. A aplicação desta metodologia é dada através da simulação de uma composição em três tipos de vias diferentes. Uma análise posterior dos resultados traz a possibilidade de uma simplificação do método de obtenção da corrente captada. Tal possibilidade é apresentada e comparada com os dados anteriormente obtidos validando-a. / This dissertation is a study of the duty cycle simulation of inverter-fed induction traction drives for DC-supplied railway system. This type of equipment is new in Brazilian railway and subway systems and the need to model and to simulate became an important issue and the aim of this dissertation. The development of the model is based on electric railway traction theory for train dynamics, on inverter-fed induction machine control and induction machine theory to calculate the input line current from power supply - one of the most important results. As an example, a modeling and simulation of one train running in three different lines is shown. The analysis of the results shows that the input line current from power supply may be obtained by a simplified model. This hypothesis is studied, the results are compared and the simplified model is then validated.

Ce travail de thèse consiste à caractériser l’endommagement subi par une mèche de carbone au cours des procédés de transformation textile, et plus particulièrement au cours du tissage des préformes pour les matériaux composites. Un protocole de caractérisation mécanique sur mèche sèche, ainsi qu’une méthode non-destructive d’analyse d’images, ont été mis au point pour quantifier cet endommagement. / This aim of this work is to characterize the damage suffered by a carbon tow in textile processing methods, and more particularly during preforms weaving for composites materials. A mechanical characterization protocol on dry tow tensile test and a non-destructive method of image analysis, have been developed to quantify this damage.

Os motores de corrente contínua convencionais são muito bem conhecidos pela sua robustez e pelo seu alto nível de controlabilidade, alem do fato de possibilitarem a operação na região de enfraquecimento de campo (modo motor), quando esta situação se fizer necessária. Por estas características, as máquinas de corrente contínua ainda são empregadas nos dias atuais em nichos específicos de utilização. Não obstante, a máquina c.c. apresenta algumas desvantagens, principalmente a intensiva e dispendiosa manutenção eletromecânica necessária para sua operação. Como opção de sanar este problema, surgiram na década de 60, as máquinas elétricas de corrente contínua sem escovas (brushless) com excitação por ímãs permanentes de fluxo trapezoidal. O problema destas máquinas se deve justamente a impossibilidade da variação de fluxo de excitação uma vez que são produzidos puramente pelos ímãs. Sendo assim, este trabalho tem como propósito, o estudo de topologias diferenciadas da máquina elétrica, através de um circuito magnético não convencional para aplicação e utilização em sistemas de tração elétrica para operação na região de enfraquecimento de campo através da variação do fluxo resultante no entreferro. Como objeto de estudo, foi focada a topologia de fluxo axial com excitação híbrida, ou seja, dupla excitação (excitação a ímãs permanentes e excitação elétrica). Para o projeto da topologia proposta, nesta tese, adicionalmente ao método analítico, foram realizadas simulações computacionais para a comparação e refinamento dos resultados das grandezas eletromagnéticas da máquina. / DC motors haves been used for almost two centuries. They are very well known not only its excellent torque response, but also because they can operate at the flux weakening region, when this situation is required. Due these characteristics, nowadays, the dc machines haves been used in specific niches of utilization. Nonetheless, this sort of machine presents a disadvantage, specifically the problem of exhaustive electromechanical maintenance required. In order to solve this type of problem, during the 1960\'s, the permanent magnet trapezoidal brushless dc machines were developed. The problem in this kind of machine is the dificulty to obtain excitation flux variation, since there is only a permanent magnet excitation system. Hence, the aim of this thesis is a study of non conventional electric machines topology for application and utilization in electric traction systems for operation at weakening flux region through the changing of resulting air-gap flux. As purpose of the study, an axial flux hybrid excitation topology was focused, i.e, a double excitation system (a permanent excitation and an electric excitation) to make its operation at the constant power region possible keeping the flux density level in the critical parts of the machine under the saturation point. Additionally, for design the topology proposed, in this thesis, computational simulations were done in order to compare with the results obtained from the analytical method.

O objetivo deste trabalho é realizar medições de distorção de tensão e corrente na entrada de subestações que alimentam sistemas ferroviários e verificar se estas atendem às normas IEEE - 519:1992 e IEC 61000-3-6:2008. Foram realizadas medições durante uma semana nas subestações retificadoras Tietê e Jaraguá, ambas da CPTM. Os resultados das medições foram comparados com simulações computacionais baseadas em um modelo simplificado do sistema de alimentação. / This study reports an experimental assessment of current and voltage distortion at the ac side of railway power supply installations and their compliance with the IEEE-519: 1992 and IEC 61000-3-6: 2008 standards. All experimental measurements were conducted using a commercially available power quality analyzer installed during a week at the CPTM rectifier substations of Tietê and Jaraguá. A simplified model was applied to computer simulations in order to calibrate the model through the comparison with experimental results.