2017
Autores
de Oliveira, JB; Pinho, TM; Coelho, JP; Boaventura Cunha, J; Oliveira, PM;
Publicação
IFAC PAPERSONLINE
Abstract
Water level regulation of irrigation canals represents a major challenge for control systems design. Those systems exhibit large dynamic variations in their operating conditions. To overcome this fact, robust controllers should be applied. The sliding mode control paradigm reveals this ability which make it a suitable candidate to be incorporated in the irrigation canal control loop. Moreover, its flexibility can be further potentiated by extending the ordinary formulation by adding fractional-order integro-differential operations. In this work, fractional-order sliding mode control is applied to the above mentioned problem. This application represents a novelty and, according to the obtained simulation results, leads to an accurate and proper performance when compared to its integer-order counterpart and to a fractional proportional-integrative controller, recently proposed for this problem.
2017
Autores
Pires, EJS; Machado, JAT; Oliveira, PBD;
Publicação
INTELLIGENT SYSTEMS DESIGN AND APPLICATIONS (ISDA 2016)
Abstract
Multi-objective optimization evolutionary techniques provide solutions for a specific problem using optimally concepts taking into consideration all the design criteria. In the last years, several multi-objective algorithms were proposed but usually the performance is measured at the end neglecting, therefore, the solution diversity along the interactions. In order to understand the evolution of the solutions this work studies the dynamic of the successive iterations. The analysis adopts the fractional entropy for measuring the statistical behavior of the population. The results show that the entropy is a good tool to monitor and capture phenomena such as the diversity and convergence during the algorithm execution. © Springer International Publishing AG 2017.
2017
Autores
de Moura Oliveira, PBD; Solteiro Pires, EJS; Novais, P;
Publicação
INTERNATIONAL JOINT CONFERENCE SOCO'16- CISIS'16-ICEUTE'16
Abstract
Hill climbing and simulated annealing are two fundamental search techniques integrating most artificial intelligence and machine learning courses curricula. These techniques serve as introduction to stochastic and probabilistic based metaheuristics. Simulated annealing can be considered a hill-climbing variant with a probabilistic decision. While simulated annealing is conceptually a simple algorithm, in practice it can be difficult to parameterize. In order to promote a good simulated annealing algorithm perception by students, a simulation experiment is reported here. Key implementation issues are addressed, both for minimization and maximization problems. Simulation results are presented.
2017
Autores
Oliveira, J; Boaventura Cunha, J; Oliveira, PM;
Publicação
Lecture Notes in Electrical Engineering
Abstract
This paper proposes the recently introduced Gravitational Search Algorithm (GSA) to tune a Sliding Mode Controller (SMC) applied on the temperature control of a grains drying system. The problem of maintaining the temperature precisely adjusted inside a silo is relevant to avoid thermal damage and spoilage losses, and thus guarantee the right conditions for storage. The objectives of setpoint tracking and disturbance rejection are incorporated into the minimization of the integral of the time-weighted absolute error. Simulation results are presented and compared with PID and with SMC tuned by Particle SwarmOptimization (PSO) and by earlier proposed tuning equations. © Springer International Publishing Switzerland 2017.
2017
Autores
Santos, F; Almeida, A; Martins, C; de Oliveira, PM; Goncalves, R;
Publicação
RECENT ADVANCES IN INFORMATION SYSTEMS AND TECHNOLOGIES, VOL 1
Abstract
This paper describes a set of models and algorithms used under a Tourism Recommendation System based in Users and Points-of-Interest (POI) profiles. This work aims to propose a recommendation system that considers user's functionality levels regarding physical and psychological issues. This proposal considers also in a different way to classify (POI) including their accessibility levels mapped with similar physical and psychological issues.
2017
Autores
de Moura Oliveira, PBD; Cunha, JB;
Publicação
2017 25TH MEDITERRANEAN CONFERENCE ON CONTROL AND AUTOMATION (MED)
Abstract
New times demand new teaching and learning methodologies. A partial flipped classroom methodology was tested in a modelling and feedback control course for undergraduate biomedical engineering. A semester course was divided in two parts: the first half using a flipped approach and the second one using a classical approach. The experience results are reported, presenting the methodology ups and downs. The use of videos as student's primer study supporting element to prepare classes in advance was explored. Using part of the class time to perform quiz group activities proved to be a major enabler to actively involve students in the learning process. The results achieved in the flipped part strongly confirm a much higher engagement and participation level from students in theoretical classes. Moreover, the flipping approach promotes students to continuously study along the semester.
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