Encontrados 25 documentos, a visualizar página 1 de 3
Design of a high-performance single-phase offline UPS with reduced switching time
Pinto, Delfim A.; Sepúlveda, JoãoA high performance single phase offline UPS with reduced switching time is proposed in the present paper. The proposed UPS can protect loads from supply outage, overvoltage and undervoltage. A bidirectional DC-DC converter takes part of the presented model, in order to reduce the system size. Thus, the converter has the capability to charge the battery and to keep a regulated voltage for the inverter’s DC-link....
Bio-inspiração aplicada a estruturas de betão : desafios e possibilidades assoc...
Sepúlveda, João MarceloDissertação de mestrado integrado em Engenharia Civil ; A impressão 3D consiste no recurso a sistemas eletro-mecânicos para criação de objetos reais a partir de modelos computacionais concebidos em tecnologias CAD (Computer Aided Design) e CAM (Computer-aided manufacturing). Estas tecnologias são largamente utilizadas no âmbito da Prototipagem Rápida em Engenharia Mecânica, tendo surgido da necessidade de cria...
Microcontroller-driven hydrogen fuel cell car
Queirós, Hugo; Lafuente, António; Sepúlveda, João; Esteves, João SenaThis paper presents a fuel cell car with 8 minutes autonomy, capable of following a white line on a black track, using infrared sensors that detect white and black colors. A servomotor controls its direction. Guidelines to the servomotor are given by a system based on an 8051 microcontroller, according to the information it receives from the infrared sensors. The hydrogen needed by the fuel cell is produced by ...
Miniature thermoelectric power plant
Moreira, António, 1957-; Freitas, Ricardo; Sepúlveda, João; Esteves, João SenaThis paper describes a miniature thermoelectric power plant made with the boiler and the water pump from an old starch iron. It also uses a computer cooling fan, which serves as electric power generator. The boiler vaporizes the water it receives from the water pump. Then, the steam is injected on the turbine of the fan, making it twirl. The voltage generated by the fan is enough to lighten a couple of LEDs. A ...
Computer-controlled model railroad
Pereira, Nino; Castro, Hélder; Sepúlveda, João; Esteves, João SenaModel railroads are good test beds for several scientific experiments on Electromagnetism, Electronics, Automation, Control and Computer Science. Moreover, they are eye-catching structures very well suited for science-fair events. This paper describes a 2m x 1m model railroad layout and a user-friendly program, built with LabVIEW graphical language. The program is able to control train direction and speed, and ...
Alternating current and direct current generator
Portela, Pedro Miguel Dourado; Sepúlveda, João; Esteves, João SenaSpinning a wire loop within a uniform magnetic field in a convenient fashion induces a voltage between the loop terminals. This effect can be used to build an electric power generator, such as the one described in this paper. A coil attached to a shaft spins within the magnetic field of a "U" shaped magnet. Three conveniently designed conductive disks allow the electrical load of the generator to be fed either ...
Thermonuclear power plant model
Esteves, João Sena; Sepúlveda, JoãoThis paper describes a model of a thermonuclear power plant with a very detailed electrical substation. The model includes facilities such as an operational railroad, a train shed, a container crane and two diesel oil filling stations. The result is very eye-catching and most suitable for the classroom or science-fair events. A brief technical explanation on the components of real-world nuclear power plants and...
Sistema digital de bajo coste para la monitorización de la calidad de energía e...
Afonso, João L.; Baptista, José; Sepúlveda, João; Martins, Júlio S.This paper describes the development of a low-cost digital system used for power quality monitoring. The system uses voltage and current Hall sensors, a standard data acquisition board, and has its processing system based on LabVIEWTM, running on a regular Personal Computer. Several parame- ters related to power quality can be analyzed through 4 different applications: “Scope and THD”, “Events PQ”, “Classical V...
Parallel association of shunt active power filters
Pregitzer, Ricardo G.; Pinto, J. G.; Sepúlveda, João; Afonso, João L.This paper describes different types of parallel association of Shunt Active Power Filters, presents computer simulation models developed in PSCAD/EMTDC, and shows simulated results for each case. The control system used in the active filters is based on the Instantaneous Reactive Power Theory (p-q Theory). The active filters use periodic sampling as switching technique. Two types of parallel associations are p...
Experimental results of a single-phase shunt active filter prototype with diffe...
Neves, Pedro; Pinto, J. G.; Pregitzer, Ricardo G.; Monteiro, Luís F. C.; Afonso, João L.; Sepúlveda, JoãoThis paper presents experimental results obtained with a developed single-phase shunt active power filter laboratory prototype operating with different switching techniques. This active filter can compensate harmonic currents and power factor in single-phase electric installations. Its power circuit is based on a two-leg IGBT inverter, with a single capacitor in the dc side, and an inductor in the ac side. Its ...
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