Browsing by Author "Touhafi, Abdellah"
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Publication Open Access Design and implementation aspects of a small anechoic room and sound-actuation system(2011) García Rodríguez, Joel; Malanda Trigueros, Armando; Touhafi, Abdellah; Escuela Técnica Superior de Ingenieros Industriales y de Telecomunicación; Telekomunikazio eta Industria Ingeniarien Goi Mailako Eskola Teknikoa; Erasmus Hogeschool Brussel (Bélgica); Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta ElektronikoaLooking for future projects, the possibility to have optimum conditions to perform microphone tests and any noise measurements of different small devices which will be constructed in the university, the need to construct a anechoic chamber was considered, so in this thesis a research about anechoic chambers was made. An acoustic anechoic chamber is a shielded room designed for performing sound measurements under conditions close to free space. Due to the difficulties that might entail the construction of a large anechoic room, we addressed the design of a chamber with smaller dimensions. This way we try to have an enclosure with conditions close to free field and to be able to perform the necessary tests with a low-cost construction. The research group wants to build an environmental emulator to test their sensor networks that are used for environmental noise study. By using multiple small rooms they want to emulate a bigger space. This report summarizes the design and construction of a small anechoic chamber, with a focus on microphone testing. Finally a low cost prototype of a small anechoic room will be built, in which we would perform the tests. The prototype has been built with low cost materials that are MDF for the walls, and fiber glass for the absorbent material. A sound actuation system has been designed too. The latter being made up of an amplifier and two speakers. The first speaker is a coaxial speaker for generating pink or white noise or sweeps. The second speaker is the tweeter to generate pure tones. For the coaxial speaker it was necessary to build a baffle. A baffle was designed in order to achieve the best performance of the loudspeaker. Finally, the design was made for a small anechoic room. We took into account the Eigen-modes, the absorption, the insulation and predominant axis of measurement as major factors of consideration. So insulation, absorption and construction issues are detailed and addressed, creating a base for the experimental evaluation for a following project.Publication Open Access Development of a measurement box to measure the 3D wind speed in an urban environment(2010) Sola Alzueta, Alejandro; Sanchis Gúrpide, Pablo; Touhafi, Abdellah; Escuela Técnica Superior de Ingenieros Industriales y de Telecomunicación; Telekomunikazio eta Industria Ingeniarien Goi Mailako Eskola Teknikoa; Erasmus Hogeschool Brussel (Bélgica); Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta ElektronikoaThe present work aims to build a low-cost three-dimensional anemometer to measure the wind speed and direction in an urban environment. To begin with, some research on basic principles in scientific literature and also in patent database was done. Secondly, a market study was carried out and two propeller anemometers were purchased. A hi-tech ultrasonic sensor was also purchased to gather accurate measurements and to serve as input for the calibration of the low-cost anemometer. The propeller anemometers were then calibrated in a wind tunnel and some unexpected measuring errors became visible. Their accuracy was not as high as it had been anticipated in the datasheets. This resulted in a collaboration with the manufacturers to test and improve their products. Some more tests were carried out and concluded with great results. Then, the three-dimensional sensor was assembled using the two propeller anemometers and it was subsequently cross-checked with an ultrasonic anemometer in a roof of the Erasmushogeschool Brussel. Finally, a program was created to collect the data from the ultrasonic sensor and store the information in a file. To sum up, this project meets all the desired goals: it works autonomously, collects the data, and is movable. In addition, some other technical statements were concluded: at low wind speeds, the propeller anemometers also had a low resolution and measurements corresponding to the horizontal plane were more accurate than those for the vertical component of the wind. One of the most significant results of this project is the fact that this work allowed helping the manufacturers to improve the propeller anemometers; their accuracy was reduced by more than 5%. In addition, the development of a program to log the wind speed data from the ultrasonic anemometer eliminated the need for an expensive data logger.Publication Open Access Diseño e implementación de un controlador de velocidad de motores de corriente alterna monofásicos(2011) Romo Zabalegui, Íñigo; Sanchis Gúrpide, Pablo; Touhafi, Abdellah; Escuela Técnica Superior de Ingenieros Industriales y de Telecomunicación; Telekomunikazio eta Industria Ingeniarien Goi Mailako Eskola Teknikoa; Erasmus Hogeschool Brussel (Bélgica); Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta ElektronikoaThis thesis is about speed control of small domestic AC motors which will be used for home automation applications. First of all, a literature study about the different types of motor for domestic applications is carried out, which has led us to choose a Permanent Split Capacitor (PSC) motor to use in this project. Later, a literature study is performed about various methods of controlling the speed of the PSC motors and come to the conclusion that the best solution is using a three-phase inverter bridge. It is required the design of the motor controller, therefore an electric drive to vary the PSC motor speed was designed using the topology of a three-phase voltage source inverter (VSI). This system allows varying the induction motors speed, varying the frequency and voltage. It was made implementing PWM (Pulse Width Modulation) control algorithms in a PIC microcontroller. The PIC microcontroller generates the control signals which are firstly sent to the optocouplers, which achieve the isolation between the control system and the power system. Optocoupler output signals are sent to the MOSFETs driver and finally to the MOSFETs, where DC bus (generated by a rectifier) is synthesized to provide two sinusoidal voltages at 90 degrees out of phase with varying amplitude and varying frequency to fed the motor, according to the V/f profile.