Browsing by Issue Date, starting with "2013-08"
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- Pedagogia Musical 1Publication . Wuytack, Jos; Boal-Palheiros, G.Este é o primeiro de uma série de cinco livros com os conteúdos dos Cursos de Pedagogia Musical orientados por Jos Wuytack, em Portugal e Espanha. Este livro é dedicado do Curso do 1º Grau e inclui os seguintes temas: treino rítmico, progressão melódica, improvisação rítmica e melódica, instrumentos Orff, canto coral e movimento, danças tradicionais do mundo, audição musical activa com o musicograma, princípios pedagógicos, metodologia e didática.
- Electricity Markets Portfolio Optimization using a Particle Swarm ApproachPublication . Guedes, Nuno; Pinto, Tiago; Vale, Zita; Sousa, Tiago; Sousa, TiagoEnergy systems worldwide are complex and challenging environments. Multi-agent based simulation platforms are increasing at a high rate, as they show to be a good option to study many issues related to these systems, as well as the involved players at act in this domain. In this scope the authors’ research group has developed a multi-agent system: MASCEM (Multi-Agent System for Competitive Electricity Markets), which simulates the electricity markets. MASCEM is integrated with ALBidS (Adaptive Learning Strategic Bidding System) that works as a decision support system for market players. The ALBidS system allows MASCEM market negotiating players to take the best possible advantages from the market context. However, it is still necessary to adequately optimize the player’s portfolio investment. For this purpose, this paper proposes a market portfolio optimization method, based on particle swarm optimization, which provides the best investment profile for a market player, considering the different markets the player is acting on in each moment, and depending on different contexts of negotiation, such as the peak and offpeak periods of the day, and the type of day (business day, weekend, holiday, etc.). The proposed approach is tested and validated using real electricity markets data from the Iberian operator – OMIE.
- Fractional model for malaria diseasePublication . Pinto, Carla; Tenreiro Machado, J. A.In this paper we study a fractional order model for malaria transmission. It is considered the integer order model proposed by Chitnis et al [1] and we generalize it up to become a fractional model. The new model is simulated for distinct values of the fractional order. Are considered two initial conditions and a set of parameter values satisfying a value of the reproduction number, R0, less than one, for the integer model. In this case, there is co-existence of a stable disease free equilibrium and an endemic equilibrium. The results are in agreement with the integer order model and reveal that we can extend the dynamical evolution up to new types of transients. Future work will focus on analytically prove some of the results obtained.
- A gallery of root locus of fractional systemsPublication . Tenreiro Machado, J. A.The root locus (RL) is a classical tool for the stability analysis of integer order linear systems, but its application in the fractional counterpart poses some difficulties. Therefore, researchers have mainly preferred to adopt frequency based methods. Nevertheless, recently the RL was considered for the stability analysis of fractional systems. One first method is by tacking advantage of commensurable expressions that occur when truncating fractional orders up to a finite precision. The second method consists of searching the complex plane for solutions of the characteristic equation using a numerical procedure. The resulting charts are insightful about the characteristics of the closed-loop system that outperform the frequency response methods. Given the limited know how in this particular topic and the shortage of literature, this study explores several types of fractional-order transfer functions and presents the corresponding RL.
- Some pioneers of the application of fractional calculusPublication . Tenreiro Machado, J. A.; Galhano, AlexandraIn the last decades fractional calculus (FC) became an area of intense research and development. This paper goes back and draws the time line of FC. We recall also important pioneers that started to apply FC during the beginning of the twentieth century. First we remember Oliver Heaviside, a pioneer in several areas of mathematics, physics and engineering. His operational calculus revealed expressions involving fractional derivatives, a premonition of the progresses that emerged later in the last decades of the twentieth century. Second it is addressed the Cole-Cole electrical relaxation. This model was a seminal work in the application of FC and plays nowadays an important role in many areas of physics and engineering.
- Metalearner based on Dynamic Neural Network for Strategic Bidding in electricity MarketsPublication . Pinto, Tiago; Sousa, Tiago; Barreira, Elisa; Praça, Isabel; Vale, ZitaThe restructuring of electricity markets, conducted to increase the competition in this sector, and decrease the electricity prices, brought with it an enormous increase in the complexity of the considered mechanisms. The electricity market became a complex and unpredictable environment, involving a large number of different entities, playing in a dynamic scene to obtain the best advantages and profits. Software tools became, therefore, essential to provide simulation and decision support capabilities, in order to potentiate the involved players’ actions. This paper presents the development of a metalearner, applied to the decision support of electricity markets’ negotiation entities. The proposed metalearner executes a dynamic artificial neural network to create its own output, taking advantage on several learning algorithms implemented in ALBidS, an adaptive learning system that provides decision support to electricity markets’ players. The proposed metalearner considers different weights for each strategy, depending on its individual quality of performance. The results of the proposed method are studied and analyzed in scenarios based on real electricity markets’ data, using MASCEM - a multi-agent electricity market simulator that simulates market players’ operation in the market.