A buck-boost converter with extended duty-cycle range in the buck voltage region for renewable energy sources

Buck-boost DC-DC converters are useful as DC grid interfaces for renewable energy resources. In the classical buck-boost converter, output voltages smaller than the input voltage (the buck region) are observed for duty cycles between 0 and 0.5. Several recent buck-boost converters have been designed to present higher voltage gains. Nevertheless, those topologies show a reduced duty-cycle range, leading to output voltages in the buck region, and thus require the use of very low duty cycles to achieve the lower range of buck output voltages. In this work, we propose a new buck-boost DC-DC converter that privileges the buck region through the extension of the duty-cycle range, enabling buck operation. In fact, the converter proposed here allows output voltages below the input voltage even with duty cycles higher than 0.6. We present the analysis, design, and testing of the extended buck-boost DC-DC converter. Several tests were conducted to illustrate the characteristics of the extended buck-boost DC-DC converter. Test results were obtained using both simulation software and a laboratory prototype.info:eu-repo/semantics/publishedVersio

Optimized robot strategy, ball filters and new referee whistle hardware filter

This paper briefly describes the main changes on the Minho Team robots since the last RoboCup edition. Work has been carried out on the robots in order to constantly improve their capabilities, based on the experience from previous participations. The main topics to deal in this paper are related with the optimization of movement on the field and also game strategy software, a ball filter recently implemented on the robots in order to follow only the correct ball. Also on this paper a description of the whole software implementation is made by describing the main Algorithm. A new referee whistle hardware filter has been developed in the last year and is here described its electronics

Development of Prometeu autonomous robot for ball handling in Eurobot

Eurobot is a robotics European challenge for the young generation (university and technical schools) which is held annually, with a different challenge in every edition, and participate around about 200 teams every year. Each game comprises two teams competing against each other and does not allow draws. This work describes the design, development and building up of an autonomous mobile robot to fulfill this challenge. This paper includes the challenge description, robot design, sensors used, the strategy used and some conclusion. The team that built this robot and participated on Eurobot is made up of 4 industrial electronic undergraduate students from University of Minho

Optimization of fast moving robots and implementation of I2C protocol to control electronic devices

This paper briefly describes the main changes in the robots from Minho Team since the last RoboCup. Work has been carried out on the robots in order to constantly improve their capabilities, based on the experiences from previous participations. The main topics to deal in this paper are related with the I2C new communications protocol recently implemented in the robots, a description of the whole electronics system based on a new diagram which contains all the devices used in the robots, the inclusion of new faster motors, a description of the robot game play strategy, some operating system remarks which are related to some requirements of our actual system, and the main conclusions related to the work carried out so far. The use of the I2C protocol forced the team to change all the electronic boards and these were completely redesigned in-house, tested and implemented on the robots.Fundação para a Ciência e a Tecnologia (FCT) - POSI/ROBO/43892/200

Patrones de m-learning en el aula virtual

Els dispositius mòbils s’han tornat omnipresents als campus universitaris, la qual cosa ha canviat la naturalesa de l’ensenyament superior i ha proporcionat una nova forma d’aprenentatge electrònic mòbil (m-learning). L’objectiu d’aquest treball és avaluar la penetració que tenen els dispositius mòbils per a l’aprenentatge en l’ensenyament superior i identificar els principals patrons d’ús. L’estudi utilitza de manera complementària dues metodologies. En primer lloc es fa un exercici de mineria web en la plataforma virtual de la universitat, per com s’exploren les tendències de l’ús d’aquesta nova tecnologia en els últims quatre cursos acadèmics i s’identifiquen els principals patrons de comportament. En segon lloc es duu a terme una enquesta a 460 estudiants universitaris per a saber el nivell de penetració de l’m-learning declarat pels estudiants. Els resultats són concloents: el 25% de les entrades al sistema LMS (Learning Management Systems) es fan amb dispositiu mòbil i el 75% dels estudiants utilitzen aquests dispositius amb finalitats d’aprenentatge. Les implicacions d’aquest estudi són importants tant per a investigadors i professors com per a les institucions que vulguin implantar aquesta metodologia d’estudi. Mobile devices are everywhere to be found on university campuses. This has changed the nature of higher education and led to a new mobile form of e-learning known as m-learning. The aim of this article is to assess the penetration of mobile devices for learning purposes in higher education and to identify the main usage patterns. To that end, the study used two complementary methodologies: web usage mining and a questionnaire survey. Web usage mining was performed to collect data from the university’s learning management system (LMS) in order to explore this new technology’s usage trends in the past four academic years and to identify the main patterns of behaviour. A questionnaire survey of 460 university students was conducted to find out about the student-declared level of m-learning penetration. The results are conclusive: 25% of accesses to the LMS were made from mobile devices and 75% of the students used these devices for learning purposes. The findings of this study have significant implications not only for researchers and lecturers, but also for institutions intending to implement this teaching/learning methodology. Los dispositivos móviles se han vuelto omnipresentes en los campus universitarios, lo que ha cambiado la naturaleza de la educación superior y ha proporcionado una nueva forma de aprendizaje electrónico móvil (m-learning). El objetivo de este trabajo es evaluar la penetración que tienen los dispositivos móviles para el aprendizaje en la educación superior e identificar los principales patrones de uso. El estudio utiliza de forma complementaria dos metodologías. En primer lugar se realiza un ejercicio de minería web en la plataforma virtual de la universidad, a través del cual se exploran las tendencias del uso de esta nueva tecnología en los últimos cuatro cursos académicos y se identifican los principales patrones de comportamiento. En segundo lugar se lleva a cabo una encuesta a 460 estudiantes universitarios para conocer el nivel de penetración del m-learning declarado por los estudiantes. Los resultados son concluyentes, el 25% de las entradas al sistema LMS (Learning Management Systems) se realizan con dispositivo móvil y el 75% de los estudiantes utilizan estos dispositivos con fines de aprendizaje. Las implicaciones de este estudio son importantes tanto para investigadores y profesores como para las instituciones que pretendan implantar esta metodología de estudio.