No description available.

The current study identified eight distinct exercise stereotypes (athletes, runners, older adults, jocks, weightlifters, judgmental girls, overweight individuals, people who do yoga) through a pilot study. An adapted version of the prototype willingness model was then used to determine whether differences exist between exercisers and non-exercisers ratings of the eight various exerciser stereotypes. No significant differences were found, which further supports the positive exerciser stereotype. The adapted version of the PWM had large proportions of explained variance. MANOVA analyses showed that overweight individuals and weightlifters differed significantly in their opinions of other exercisers. Overweight individuals had negative ratings towards jocks, athletes and judgmental girls and weightlifters showed negative ratings of yoga participants. Both of these exercisers may benefit from a fitness center absent of these respective exercisers.

Nos dias de hoje, o aumento na demanda de energia no Brasil, associado a fatores econômicos e ambientais, tem dificultado a criação de novas usinas hidrelétricas, necessárias para suprir essa demanda adicional e aumentar a confiabilidade do sistema. Nesse contexto, a geração distribuída se destaca como uma solução adequada, pois economiza investimentos em redes de transmissão e distribuição, reduz perdas e diversifica a matriz energética do sistema elétrico, tornando-o mais robusto e eficiente. Dentre as fontes de energia utilizadas em sistemas de geração distribuída, a microturbina apresenta algumas vantagens em relação a outros modelos de GD, como por exemplo, a possibilidade da utilização de vários tipos de combustíveis. Para verificar as características de operação das microturbinas, foram realizadas simulações baseadas em modelos matemáticos presentes na literatura técnica. Porém, devido às altas velocidades de rotação das turbinas a gás, a energia gerada possui frequências muito altas para ser aproveitada diretamente pelos consumidores, sendo necessária uma interface eletrônica para adequação da energia elétrica. Neste trabalho é abordado o estudo, simulação e implementação da primeira etapa desta interface, um retificador trifásico com correção de fator de potência, para a geração de um barramento de corrente contínua com tensão estável, mantendo as correntes de entrada do retificador com formato senoidal e em fase com a tensão. / Nowadays, the increase in energy demand in Brazil, associated with economic and environmental factors, has hindered the creation of new power plants needed to provide this additional demand and improve system reliability. In this context, distributed generation stands out as an appropriate solution because it saves investments in transmission and distribution, reduces losses and diversify the energy matrix of the electrical system, making it more robust and efficient. Among the energy sources used in distributed generation systems, the microturbine has some advantages over other models of GD, such as the possibility of using various types of fuel. To verify the operating characteristics of microturbines, simulations were performed based on mathematical models present in literature. However, due to high rotation speeds of gas turbines, the energy generated has very high frequencies to be used directly by consumers, which requires an electronic interface to adequate the electricity. This work describe the study, simulation and implementation of the first stage of this interface, a three-phase rectifier with power factor correction, to generate a DC bus voltage stable, keeping the rectifier input current format sinusoidal and in phase with the voltage generated by the microturbine.

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-11-08T17:40:29Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertacao_Moraes_ABNT.pdf: 5928696 bytes, checksum: ffd79ada8f98120795b81b1c40caf20d (MD5) / Made available in DSpace on 2016-11-08T17:40:29Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertacao_Moraes_ABNT.pdf: 5928696 bytes, checksum: ffd79ada8f98120795b81b1c40caf20d (MD5) Previous issue date: 2015-10-29 / Cnpq / Quando comparados aos retificadores tradicionais a diodo ou tiristor, os retificadores PWM têm algumas vantagens como corrente de entrada senoidal, filtro capacitivo pequeno e fator de potência controlado. No entanto, esses conversores são sensíveis a tensões desbalanceadas e transitórios de tensão. Problemas que ocorrem frequentemente em sistemas de potência trifásicos devido a cargas desbalanceadas e faltas no sistema elétrico. Sob essas condições, alguns problemas como; ripple na tensão o barramento CC e presença de harmônicos na correntes da rede podem ser evidenciados. Assim, para manter a tensão do barramento CC constante sem injetar mais correntes harmônicas na rede, surgem duas opções básicas. A primeira é a utilização de grandes filtros capacitivos para atenuar o ripple de tensão, com a possibilidade de ressonância no sistema, além do aumento dos custos e tamanho do retificador tradicional. A segunda alternativa, na qual desenvolve-se o trabalho, é a utilização de uma estratégia de controle, durante faltas no sistema. O trabalho realiza uma análise comparativa de três estratégias de controle. / When compared to traditional thyristor or diode rectifiers, the rectifiers PWM have some advantages like sinusoidal input current, small capacitive filter and power factor control. However, such converters are susceptible tensions unbalanced and transient voltage. Problems that often occur in systems three-phase power due to unbalanced loads and faults in the electrical system. Under these conditions, some problems like; ripple on the DC bus voltage and the presence of harmonic currents in the network can be evidenced. Thus, to maintain tension the constant DC bus without injecting more harmonic currents in the network, there are two basic options. The first is the use of large capacitive filters to attenuate the ripple voltage, with the possibility of resonance in the system, and increased costs and size of traditional rectifier. The second alternative, which develops in the work, is the use of a control strategy during system faults. The work carries a comparative analysis of three control strategies

Nos dias de hoje, o aumento na demanda de energia no Brasil, associado a fatores econômicos e ambientais, tem dificultado a criação de novas usinas hidrelétricas, necessárias para suprir essa demanda adicional e aumentar a confiabilidade do sistema. Nesse contexto, a geração distribuída se destaca como uma solução adequada, pois economiza investimentos em redes de transmissão e distribuição, reduz perdas e diversifica a matriz energética do sistema elétrico, tornando-o mais robusto e eficiente. Dentre as fontes de energia utilizadas em sistemas de geração distribuída, a microturbina apresenta algumas vantagens em relação a outros modelos de GD, como por exemplo, a possibilidade da utilização de vários tipos de combustíveis. Para verificar as características de operação das microturbinas, foram realizadas simulações baseadas em modelos matemáticos presentes na literatura técnica. Porém, devido às altas velocidades de rotação das turbinas a gás, a energia gerada possui frequências muito altas para ser aproveitada diretamente pelos consumidores, sendo necessária uma interface eletrônica para adequação da energia elétrica. Neste trabalho é abordado o estudo, simulação e implementação da primeira etapa desta interface, um retificador trifásico com correção de fator de potência, para a geração de um barramento de corrente contínua com tensão estável, mantendo as correntes de entrada do retificador com formato senoidal e em fase com a tensão. / Nowadays, the increase in energy demand in Brazil, associated with economic and environmental factors, has hindered the creation of new power plants needed to provide this additional demand and improve system reliability. In this context, distributed generation stands out as an appropriate solution because it saves investments in transmission and distribution, reduces losses and diversify the energy matrix of the electrical system, making it more robust and efficient. Among the energy sources used in distributed generation systems, the microturbine has some advantages over other models of GD, such as the possibility of using various types of fuel. To verify the operating characteristics of microturbines, simulations were performed based on mathematical models present in literature. However, due to high rotation speeds of gas turbines, the energy generated has very high frequencies to be used directly by consumers, which requires an electronic interface to adequate the electricity. This work describe the study, simulation and implementation of the first stage of this interface, a three-phase rectifier with power factor correction, to generate a DC bus voltage stable, keeping the rectifier input current format sinusoidal and in phase with the voltage generated by the microturbine.

As manufacturers, the automotive industry, and many other sectors face an increasingly competitive global business environment; they seek opportunities to reduce production costs by reducing energy consumption. Energy costs have become one of the fastest-rising expenses of doing business, and the industrial sector is rushing to implement new energy conservation initiatives. Pressurized air, as an important source of energy, has been widely used by various industries, providing simple solutions for automated lines. In this project, an Accumulator-Based Equalization (ABE) strategy was combined with a knowledge-based PWM (Pulse Width Modulation) protocol, and then incorporated into an integrated solenoid valve to increase the energy efficiency of pneumatic systems through the optimization of ow consumption. Modeling and simulation of the proposed system was carried out to assess the proposed ideas and reduce the cost of system developments. An experimental setup was constructed to assess the performance of the proposed strategy when implemented on configured pneumatic control valves. Equalization was performed at home positions of a typical linear actuator, where the chambers of the pneumatic actuators were momentarily connected to each other. Furthermore, during the extension and retraction, a knowledge-based PWM signal was applied to the valves to maintain the actuator dynamics in an acceptable posture. To obtain the knowledge-based PWM signal, an expert-fuzzy controller was designed to control the speed of the actuator. This knowledge-based protocol was based on fuzzy structures, which were implemented on the configured pneumatic valves in an open-loop fashion to decrease the amount of ow consumption without compromising the dynamic performance of the pneumatic actuators. The identified duty cycles profiles from the expert fuzzy controller were implemented on an open-loop system. It was observed that, while an open-loop system is used, the pressurized air can be saved about 20% under 50 N load and almost 10% under 150 N load. "Smoothness index" was defined as a measure of the piston motion smoothness when applying the proposed strategies. In addition to smoothness of the motion in the closed-loop control methods, the energy-saving results were compared to the results of the open-loop system and the performance under different conditions was evaluated.

As manufacturers, the automotive industry, and many other sectors face an increasingly competitive global business environment; they seek opportunities to reduce production costs by reducing energy consumption. Energy costs have become one of the fastest-rising expenses of doing business, and the industrial sector is rushing to implement new energy conservation initiatives. Pressurized air, as an important source of energy, has been widely used by various industries, providing simple solutions for automated lines. In this project, an Accumulator-Based Equalization (ABE) strategy was combined with a knowledge-based PWM (Pulse Width Modulation) protocol, and then incorporated into an integrated solenoid valve to increase the energy efficiency of pneumatic systems through the optimization of ow consumption. Modeling and simulation of the proposed system was carried out to assess the proposed ideas and reduce the cost of system developments. An experimental setup was constructed to assess the performance of the proposed strategy when implemented on configured pneumatic control valves. Equalization was performed at home positions of a typical linear actuator, where the chambers of the pneumatic actuators were momentarily connected to each other. Furthermore, during the extension and retraction, a knowledge-based PWM signal was applied to the valves to maintain the actuator dynamics in an acceptable posture. To obtain the knowledge-based PWM signal, an expert-fuzzy controller was designed to control the speed of the actuator. This knowledge-based protocol was based on fuzzy structures, which were implemented on the configured pneumatic valves in an open-loop fashion to decrease the amount of ow consumption without compromising the dynamic performance of the pneumatic actuators. The identified duty cycles profiles from the expert fuzzy controller were implemented on an open-loop system. It was observed that, while an open-loop system is used, the pressurized air can be saved about 20% under 50 N load and almost 10% under 150 N load. "Smoothness index" was defined as a measure of the piston motion smoothness when applying the proposed strategies. In addition to smoothness of the motion in the closed-loop control methods, the energy-saving results were compared to the results of the open-loop system and the performance under different conditions was evaluated.

No description available.

The TI TMS320LF2407A DSP is used as the control kernel in this thesis, proposing a method of sensorless control for the brushless DC motor. With six-step pulse-width modulation, the information of the back electromagnetic signals can be detected and is used to estimate the rotor position instead of the Hall sensors. To strengthen the system and reduce the power consumption, we propose the idea of close loop framework, including speed feedback and current feedback. Then, the phase-change signal is set as no delayed, 15 degree delayed, and 30 degree delayed and compare the results each other. Finally, setting up experimental framework, to verify the superiority of sensorless drivers with close-loop framework, and choosing better phase-change degree to improve system and efficiency.

This thesis develops a hardware circuit implementation of an active filter for reducing a SRM drives input current ripple or equivalently to improve the SRM drives input power quality. Its an alternative to the simple inductor and capacitor in a conventional passive filter. For the same filtering capability the size of the two physical capacitors in the active filter will be much less than the size of the capacitor in a conventional filter. Also the size of the two inductors in the active filter will be much less than the size of the inductor in a conventional filter. Some of this size reduction will be consumed by the power semiconductors but their size is much smaller than the filter components being replaced. This thesis describes the design of the active filter circuit which can replace the conventional passive filter. In this thesis, feedback control is also used with the active filter to force the filter voltage to be the desired value to minimize the effects of the circuits resonances. The active filter circuit is tested experimentally with a test circuit that mimics the current ripple generated by an SRM drive system. The experimentally generated output is verified by comparing it with simulation results from a detailed SIMULINK model and a B2 spice model of the experimental system.