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Publicações

2014

Optimizing Large Scale Problems With Metaheuristics in a Reduced Space Mapped by Autoencoders-Application to the Wind-Hydro Coordination

Autores
Miranda, V; Martins, JD; Palma, V;

Publicação
IEEE TRANSACTIONS ON POWER SYSTEMS

Abstract
This paper explores a technique denoted LASCA to solve large scale optimization problems with metaheuristics by reducing the search space dimension with autoassociative neural networks. The technique applies autoencoders as a reversible mapping between the original problem space and a reduced space. A metaheuristic then evolves in the latter, having its objective function assessed in the original space. The technique is illustrated with an application of an Evolutionary Particle Swarm Optimization (EPSO) algorithm to four benchmarking unconstrained optimization functions and to a wind-hydro constrained coordination problem. The new technique allows an improvement in the quality of the solutions attained.

2014

Comparison of Various Operational Statuses of PIEV Aggregators with Home-Charged EVs and Parking Lots

Autores
Neyestani, N; Damavandi, MY; Shafie Khah, M; Catalao, JPS;

Publicação
2014 IEEE PES GENERAL MEETING - CONFERENCE & EXPOSITION

Abstract
Emerging technologies arising in modern power systems have propelled the presence of new agents to manipulate these facilities. Participation of plug-in electric vehicles (PIEVs) in the electricity market is one of the main issues in this environment. PIEV participation in market place can affect the agent's strategy. Therefore, this paper investigates two states of power system where individual aggregators participate in the power market on behalf of home-charged PIEVs and parking lots (PLs) separately, as well as the coordinated version of the problem. Several scenarios are developed for deriving specific characteristics of PIEVs in home levels and in PLs. An optimization model is built and solved using mixed integer linear programming. The results are produced to suggest the optimum procedure for an aggregator to whether take the authority of home-charging PIEVs and PLs individually or coordinately.

2014

Use of laser speckle and entropy computation to segment images of diffuse objects with longitudinal motion.

Autores
Vaz, P; Capela, D; Pereira, T; Correia, C; Ferreira, R; Humeau Heurtier, A; Cardoso, J;

Publicação
SECOND INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS

Abstract
A system using laser speckle effect is proposed to segment images reflecting vibration movements of diffuse targets. Longitudinal movements are difficult to identify when simple imaging systems are used. The proposed system produces a two dimensional segmentation of the target and it is sensitive to longitudinal movements. The speckle effect, produced when coherent light is reflected and interferes when hitting rough surfaces, can be used in order to accomplish this purpose. A pattern with high and low intensity spots is observed depending on the illuminated scene. In our optical system, two silicone membranes are illuminated using a beam expanded laser source and their patterns are recorded using a video camera. One of the membranes experiences a longitudinal controlled movement while the remaining scene is still. Speckle data is processed using a temporal gradient and a regional entropy computation. This method produces a binary individual pixel classification. Four sets of parameters have been tested for the entropy computation and the area under the receiver operating characteristic (ROC) curve was used to select the best one. The selected set-up achieved a ROC value of 0.9879. A data set with 12 different membrane velocities was used to define the threshold that maximizes the classifier accuracy. This threshold was applied to a validation data-set composed by 4 sinusoidal movements with distinct velocities. The accuracy of this technique has achieved values between 92% and 97%. The results show that the target was accurately identified with the optical non-contact apparatus and the developed algorithm.

2014

A Virtual Environment based Serious Game to Support Health Education

Autores
Gomes, T; Abade, T; Campos, JC; Harrison, MD; Silva, JL;

Publicação
EAI Endorsed Trans. Ambient Syst.

Abstract
APEX was developed as a framework for ubiquitous computing (ubicomp) prototyping through virtual environments. In this paper the framework is used as a platform for developing a serious game designed to instruct and to inform. The paper describes the Asthma game, a game aimed at raising awareness among children of asthma triggers in the home. It is designed to stimulate a healthier life-style for those with asthma and respiratory problems. The game was developed as the gamification of a checklist for the home environment of asthma patients.

2014

Production and characterisation of cork pellets: An alternative for sustainable energy recovery

Autores
Nunes, LJR; Matias, JCO; Catalão, JPS;

Publicação
Renewable Energy and Power Quality Journal

Abstract
The cork industry presents itself as one of the most entrepreneurial in the Portuguese industrial sector, contributing significantly to the increase of exports. However, it is an industry in which the use of raw materials is maximised leaving a large volume of waste. The cork industry has tried to take advantage of these residues, mainly through direct energy recovery, despite the technical and safety difficulties presented by the use of such low density material, which complicates and hinders its transportation for industrial uses outside the area in which it is produced. The densification process opens new doors for such use and also for its storage, because it produces better results when compared with other more common products, such as wood sawdust or even forest and agricultural waste. Thus, cork pellets emerge as a safer and more easily transportable alternative for energy recovery from cork dust and other granulated types of cork waste, which offer the prospects for wider use. The results demonstrate that cork pellets have higher calorific value when compared with other biomass pellets; typically, approximately 19 MJ/kg with 2% volume of ashes, which is equivalent to that obtained from the combustion of pellets produced from combined forest and agricultural waste with a bulk density of 640 kg/m3, which offers real advantages in terms of logistics.

2014

Preface

Autores
Vanschoren, J; Brazdil, P; Soares, C; Kotthoff, L;

Publicação
CEUR Workshop Proceedings

Abstract

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