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- A 5-step pedagogical design for engineering coursesPublication . Rafael, Silviano; Justino, JúliaThis paper presents the design of a 5-step pedagogical framework based on student-centered approach prepared for engineering educators’ mindset. This pedagogical framework has been applied and tested in various technical and engineering course units, been adapted for the new students of Generation Z. This framework can be a pedagogical toolbox in adapting the teaching and learning activities to the students’ needs, also measuring qualitatively the students’ dynamics and academic performance. So far, in the course units where this pedagogical method was applied there was a 20% increase of the success rate and a reduction of the drop-out rate between 5% to 15%.
- Active learning with technology: developing practical skills with a flexible teaching platformPublication . Rafael, Silviano; Justino, JúliaThe laboratory classes allow students to deal with the equipment and technology, to study techniques and to analyse, model and test the laboratory procedure. The active construction of knowledge in a laboratory environment is strongly based on experimentation, requiring an extensive workload of laboratory practices. In this paper, a flexible laboratory platform for teaching and learning, developed for enhancing practical learning experiences within industrial automation process for engineering students, is presented as an innovative, transformative, technological and feasible alternative to classic laboratories, which are much more expensive. Through pedagogical techniques of active learning depending on the complexity knowledge level of the topics addressed, the laboratory practices provide a bridge of knowledge between the theoretical and the practical contents, developing critical sense, teamwork, autonomy, time management, problem-solving, among other soft skills, which strongly contributes to a solid training for engineering labour market current need.
- Adaptive Allocation of Virtual Radio Resources overHeterogeneous Wireless NetworksPublication . Caeiro, Luísa; Cardoso, Filipe; Correia, LuísVirtual Networks and cloud services are hot topics nowadays, being considered, together with the information centric approach, key elements for the Future Internet. In this paper, an adaptive radio resource allocation mechanism for virtual resources sharing a common heterogeneous wireless infrastructure is presented and evaluated. The Virtual Network Radio Resource Allocation (VRRA) strategy being proposed takes advantage of the set of shared resources available within a cluster of wireless resources from different Radio Access Technologies (RATs), optimising their utilisation in order to maintain the contracted capacity. Simulation results show that the introduction of VRRA allows supporting the minimum bandwidth requirement in a wireless cluster, composed of several physical base stations from different RATs. For the Virtual Network providing high data rates and guaranteed services as presented in this paper, the Virtual Network Operator Satisfaction Level can be improved by 40% with the introduction of VRRA mechanisms.
- Addressing Multiple Virtual Resources in the Same Geographical AreaPublication . Caeiro, Luísa; Cardoso, Filipe; Correia, LuísThis paper addresses the virtualisation of wireless access in order to provide the required capacity (data rate) to a Virtual Base Station (VBS). The approach is based on a Virtual Radio Resource Allocation algorithm, OnDemandVRRA, which manages the allocation of the physical radio resources to VBSs’ end-users, in order to follow the contract and maintaining isolation among VBSs, according to the type of guarantees of the VBSs, the amount of contracted capacity, and VBSs’ utilisation. Taking the variability of the wireless medium into account, the algorithm continuously influences the RRM mechanisms, namely admission control and MAC scheduling, to be aware of the VBSs’ state relative to the service level agreement, in order to compensate for this variability. The algorithm has been tested to evaluate its behaviour, concerning the amount of VBSs created over a given geographical area served by a set of base stations. It can be concluded that changing the quantity of created VBSs as well as the contracted data rate in the cluster, GRT VBSs get their minimum contracted data rate. It is also verified that the best Radio resource Unit (RU) efficiency is achieved when the strategy for the overall capacity provision is to limit the capacity contracted by GRT VNets, overbooking the capacity contracted by BE VNets. In this case, the RU efficiency increases 30% comparing to the situation where the overbooking is done by GRT VBSs.
- Alinhamento Pedagógico Construtivo na Aprendizagem Dinâmica sobre Máquinas ElétricasPublication . Rafael, Silviano
- An Adaptive PID Speed Controller for an 8/6 Switched Reluctance MachinePublication . Rafael, Silviano; Santos, P. J.; Pires, A. J.This paper presents a classical controller with parameters adaptation capability, in an automatic way. This controller is based on a PID where a parameters adaptation algorithm is used and applied to the switched reluctance motor (SRM) speed control. This PID design do not require any kind of adjustment or calibration from the operator. The parameters adaptation algorithm implemented is based on one fuzzy system with a Takagi-Sugeno inference mechanism with some simplifications. These simplifications had the goal to select the parameters adaptation algorithm contributing for a fast controller response. The developed adaptive PID algorithm was modelled and simulated.
- An open-source UFBGA m-board for wearable devicesPublication . A. Antunes, R.; Palma, Luís BritoThis paper presents the development of an open-source, low-sized, BGA microcontroller breakout board, that can be used for the development of wearable and cyber-physical prototypes. The board is based on the low power, 8-bit, ATtiny20-CCU Microchip AVR microcontroller. The ATtiny20-CCU can be programmed without bootloader, using the Atmel Tiny Programming Interface (TPI), instead of In-System Programming (ISP). The C code used to program the microcontroller can be written and compiled using the Microchip Studio freeware platform. The ATtiny20-CCU Ultra Fine-pitch Ball Grid Array (UFBGA) packaging technology allows the shrinkage of the conceived Electroless NickelImmersion Gold (ENIG) Printed Circuit Board (PCB) to a size of only 15.5 13 mm. Its low cost also makes it a viable option for developing many educational electronic projects, especially for Instrumentation and Assistive Technology. The contribution of this paper is mainly the hardware prototype design, the PCB manufacturing, building and test of a very low-sized open source m-breakout PCB board, for wearable Instrumentation applications, towards the emergent Society/Industry 5.0.
- Application of active learning techniques on Electrical Machines course in classroom environment: pedagogical strategy and resultsPublication . Rafael, Silviano; Justino, Júlia
- Beamforming Strategies for Energy Efficient Transmission in LTEPublication . Cardoso, Filipe; Correia, Luís; Petersson, Sven; Boldi, MauroThe actual internet traffic growth is challenging the sustainability of mobile networks, therefore, the energy efficiency of the mobile communication infrastructure becomes a topic of particular relevance. Decreasing CO2 emissions and energy demands while expanding the mobile infrastructure to satisfy traffic demands is essential. In this paper the energy efficient use of beamforming techniques and active antennas, in which an advanced antenna is utilized to direct the transmitted signal in a narrow direction, is evaluated. Slow beamforming based on reconfigurable antennas, exploits medium/long term variations of traffic in order to save energy. Fast beamforming, on the contrary, is immediately following the traffic distribution and can even allow saving more energy. From simulations it is observed that, when compared to existing state-of-art bases base stations, in a dense urban environment reconfigurable beamforming allows a maximum gain of about 8%. Adaptive beamforming, allows an additional consumed power reduction of up to 40%. Hence, the overall power consumption reduction that can be achieved by combining these techniques can be as high as 50%.
- Bidirectional Boost/Buck Quadratic Converter for Distributed Generation Systems with Electrochemical Storage SystemsPublication . Foito, Daniel José Medronho; Cordeiro, A.The increasing number of distributed generation systems using renewable and non-conventional energy sources show the trend of future generation systems. Most of these systems require power electronic converters as an interface between the DC voltage buses and electrochemical storage systems. Such storage systems, like batteries or supercapacitors, usually need bidirectional DC-DC converters to allow their charge or discharge according with necessary operation conditions. In this paper, a non-isolated bidirectional Buck-Boost converter with high voltage gain for electrochemical storage devices used in distributed generation systems is presented. To achieve high voltage gain ratios, the proposed topology presents quadratic characteristics in both step-down (Buck) and step-up (Boost) operation modes. In addition to the wide conversion range, it presents continuous input and output current, reduced charging/discharging ripple and simple control circuitry. All these features allow the energy exchange smoothly and continuously resulting in a longer durability of storage devices. The principle of the operation of the proposed converter in both operation modes, as well as their theoretical analysis will be discussed. The performance of this bidirectional power converter is confirmed through simulation and experimental results.