Conversor para pulsos elétricos de alta tensão, de curta duração, para processos de geração de ozônio

Pós-graduação em Engenharia Elétrica - FEIS

Desenvolvimento de um conversor estático PWM para o acionamento de LED’S para iluminação publica

This work deals with the development of a switched-mode power supply circuit based on a Buck topology converter with a Boost Rectifier One-Cycle Control with Power Factor Correction developing, thus, a source of direct current for a module of 50 power LEDs that will be used in a lamp for public street lightning. It is presented, at first, some aspects about the most common technologies used in lamps of public street lightning in Brazil and a comparison with the White LED high power, which is the one that presents itself as the most promising among the existing market. Then it is presented the detailed development of the static converter switched PWM, consisting of a Boost rectifier with power factor correction and methodology of control One-Cycle Control associated with a Buck converter controlled by a PI method that operates as a direct current source . At the end of the simulation results of the circuit through the PSIM software are presented to verify the design behavior

Desenvolvimento de estrutura para purificação de água potável, através da irradiação de UV com lâmpadas fluorescentes especiais

Pós-graduação em Engenharia Elétrica - FEIS

Análise de geradores piezelétricos acoplados com circuitos retificadores operando em regime caótico

Pós-graduação em Engenharia Mecânica - FEIS

The kinetic of mullite crystallization: Effect of water content

The kinetic of mullite crystallization from sol–gel method, with different water content, was investigated under non-isothermal conditions using DTA. The sols were obtained from Al(NO3)3.9H2O (ANN) and Si(OC2H5)4 (TEOS) mixtures by varying the water–alcohol content of the system. The crystalline phase changes were verified by X-ray diffraction (XRD). For a sample prepared using ethanol-based alkoxide solution (M0), only Al-poor mullite (p-mullite) crystallizes at 1000 °C; for the one synthesized with low water concentration (M6) Al-rich mullite (r-mullite) and spinel crystallize together; and for a sample prepared using a water-based alkoxide solution only spinel is formed. Thus, the variation of water contents during the synthesis caused great variations in the course of mullitization process. The average value of the apparent activation energy determined for p-mullite, r-mullite and spinel phase crystallization were found to be E = (899 ± 61) kJ mol−1, E = (1015 ± 272) kJ mol−1 and E = (980 ± 196) kJ mol−1, respectively. These results showed that sample M(0) was a monophasic gel, where aluminum and silicon atoms are mixed at a molecular level while sample M(100) was a diphasic gel, where silicon and aluminum atoms are distributed in a nanometric level. The fast reaction between TEOS and water molecules is responsible for this great difference in the sample's homogeneity. The kinetic model of the crystallization process was determined using Malek's procedure. It was established that the crystallization of p-mullite, r-mullite and spinel phase can be described by Šesták–Berggren autocatalytic model.

Inflection and stability points of diphasic logistic analysis of growth

Growth functions with inflection points following a diphasic model, can be adjusted by two approaches using segmented regression or the sum of two functions. In both cases, there are two functions, one for each phase, with inflection and stability points. However, when they are summed, the result is a new function and the points of inflection and stability are different from those obtained from using each function individually. A method to determine these points in a diphasic logistics sum of functions is suggested and the results obtained from fitting the models to eucalyptus growth data showed a better fit of the logistic diphasic sum as compared with segmented regression and monophasic logistic models.

Sistema de geração e armazenamento de energia elétrica utilizando transdutor piezelétrico na forma pulsada

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Inclusão das representações de gary e de skilling-umoto em modelos de linhas de transmissão trifásicas: Aplicação em simulações de transitórios eletromagnéticos em sistemas de energia elétrica

Pós-graduação em Engenharia Elétrica - FEIS

Projeto de controladores robustos para acionamento de um motor de indução trifásico

Pós-graduação em Engenharia Elétrica - FEIS

Retificador entrelaçado com elevado fator de potência para operação de um veículo trólebus alimentado por redes em CA Ou CC

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.

Ultrassonografia modo B de alta resolução modo Doppler e uso de contraste de microbolhas na avaliação testicular de gatos domésticos

Pós-graduação em Medicina Veterinária - FCAV