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Publicações

2020

Model Predictive Current Control of Switched Reluctance Motor Drive: An Initial Study

Autores
Pereira, M; Araújo, RE;

Publicação
Technological Innovation for Life Improvement - 11th IFIP WG 5.5/SOCOLNET Advanced Doctoral Conference on Computing, Electrical and Industrial Systems, DoCEIS 2020, Costa de Caparica, Portugal, July 1-3, 2020, Proceedings

Abstract
A considerable amount of research within the last few decades has been focusing on controllers for switched reluctance motor drives and how they affect the torque ripple. Despite all its potentials, there are still major concerns and obstacles to overcome concerning the dependency of the magnetic characteristic of the switched reluctance motor. This work targets these concerns by proposing an initial study of the fundamentals of a drive scheme using a finite set model predictive control for a switched reluctance motor through an asymmetric bridge converter. The implementation of this scheme is the main contribution of this paper. The method uses the dynamic model of the motor to estimate the future behavior of the current for each converter state. A cost function then evaluates which switching state minimizes the current error and applies it to the motor. Some simulation results illustrate the technique. Simulation results show the good performance of the method with fast and accurate transient response. © IFIP International Federation for Information Processing 2020.

2020

Optical fiber probes for trapping and backscattered signal analysis of sub-mm particles

Autores
Rodrigues, SM; Paiva, JS; Silva, FM; Coelho, L; Marques, PVS; Cunha, JPS; Jorge, PAS;

Publicação
Optics InfoBase Conference Papers

Abstract
Optical tweezers based on metallic-coated tapered optical fibers with an aperture at the apex are fabricated and their sensing ability is tested. Preliminary results show robustness in differentiating between a trapped and no trapped state. © 2021 The Author(s).

2020

Height Optimization in Aerial Networks for Enhanced Broadband Communications at Sea

Autores
Teixeira, FB; Campos, R; Ricardo, M;

Publicação
IEEE ACCESS

Abstract
The Blue Economy has been growing in sectors such as offshore renewable energy, aquaculture, marine biotechnology, and deep sea mining. However, suitable wireless and mobile communications are lacking offshore. On the one hand, there is no coverage from terrestrial networks; on the other hand, satellite communications are still narrowband and expensive. Recently, the use of multi-hop airborne communications has been proposed to extend the coverage from terrestrial networks offshore but the communications range of these solutions is highly dependent on the height of the communications nodes. In this paper, we study the RF signal propagation in the maritime environment when the height of the receiver is changed and propose a position control approach for airborne multi-hop networks that maximizes the network capacity by taking full advantage of the signal reflections on the sea surface. The results obtained show that the proposed approach can provide lower propagation losses and higher network throughputs than random or fixed height approaches.

2020

Teaching Software Engineering Topics Through Pedagogical Game Design Patterns: An Empirical Study

Autores
Flores, N; Paiva, ACR; Cruz, N;

Publicação
INFORMATION

Abstract
Teaching software engineering in its many different forms using traditional teaching methods is difficult. Serious games can help overcome these challenges because they allow real situations to be simulated. However, the development of serious games is not easy and, although there are good practices for relating game design patterns to teaching techniques, there is no methodology to support its use in a specific context such as software engineering. This article presents a case study to validate a methodology that links the Learning and Teaching Functions (LTF) to the Game Design Patterns (PIB) in the context of Software Engineering Education. A serious game was developed from scratch using this methodology to teach software estimation (a specific topic of software engineering). An experiment was carried out to validate the effectiveness of the game by comparing the results of two different groups of students. The results indicate that the methodology can help to develop effective educational games on specific learning topics.

2020

A Fuzzy Modal Logic for Fuzzy Transition Systems

Autores
Jain, M; Madeira, A; Martins, MA;

Publicação
ELECTRONIC NOTES IN THEORETICAL COMPUTER SCIENCE

Abstract
This paper intends to contribute with a new fuzzy modal logic to model and reason about transition systems involving uncertainty in behaviours. Our formalism supports fuzziness at transitions and on the proposition symbols assignment levels. Against of other approaches in the literature, our bisimulation and bisimilarity notions generalise the analogous standard notions of classic modal logic and of process algebras. Moreover, the outcome of our logic is also fuzzy, with the semantic interpretation of connectives supported by the Godel algebra.

2020

Fault diagnosis in DC-DC power converters based on parity equations

Autores
Mattos, WJ; Araujo, RE;

Publicação
Proceedings - 2020 International Young Engineers Forum, YEF-ECE 2020

Abstract
This paper presents an approach based on parity equations for the problem of fault diagnosis in Buck and Boost converters. The basic idea of this method consists of to formulate a set of residues that compare the difference between the signals measured from the power circuit with an equation model describing the nominal behavior of the power converter. The fault detection algorithm is based on checking the residuals of the inductor current and output voltage. The fault signatures matrix was obtained using a theoretical analysis of residuals in order to establish an appropriate and effective fault isolation algorithm for converters running in continuous mode. Simulation results demonstrate the effectiveness of the method to isolate the main faults in the Buck and Boost power converters. © 2020 IEEE.

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