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Publicações

Publicações por LIAAD

2015

Wind farm distribution network optimization

Autores
Cerveira, A; Baptista, J; Pires, EJS;

Publicação
INTEGRATED COMPUTER-AIDED ENGINEERING

Abstract
Wind energy production have been increasing in last years, with an annual growth of the installed capacity rate about 20%. It becomes important to develop optimization techniques to improve the effectiveness of the wind farms. One field in which this can be done is in the distribution network design that interconnects the turbines and the substation. This paper proposes two mathematical models to obtain the optimal electrical interconnection configuration of the wind farm turbines, considering technical constraints. One model minimizes the installation costs and the other one minimizes the installation costs and the energy losses costs registered during the wind farm lifetime. This problem corresponds to a capacitated minimum spanning tree with additional constraints. The proposed models were applied in two real wind farms. A sensitivity analysis is performed over two electrical parameters, the power factor and the load factor. The results show that the electrical losses of the wind farm must be taken into account in the optimization process.

2015

AFINA-te - A Healthy Lifestyle Information Website, Online Food Diary and Exercise Log Directly Towards Children

Autores
Guimarães, N; Lebres, VF; Ribeiro, J;

Publicação
CSEDU 2015 - Proceedings of the 7th International Conference on Computer Supported Education, Volume 1, Lisbon, Portugal, 23-25 May, 2015.

Abstract
Childhood obesity is according to the World Health Organization one of the most concerning problems today. Educating children to a healthier lifestyle is a difficult task due to the lack of interest or concern that they demonstrate. The interest that children have in technology and the time they spent online in games or simply surfing the web may be seen as an opportunity to instill knowledge about healthy eating and healthy lifestyle. There are already several online health counseling websites but it seems to exist a lack of such platforms directly towards to children. Afina-te website is an online platform that aims to monitor and educate children to a healthier lifestyle through the exposition of information, interactive applications and educational games. It is also capable of provide feedback about what users eat and the exercise they practice. This paper describes the development and resulting health counseling website.

2015

Animation and Automatic Evaluation in Supporting the teaching of Programming

Autores
Tavares, PC; Gomes, EF; Henriques, PR;

Publicação
PROCEEDINGS OF THE 2015 10TH IBERIAN CONFERENCE ON INFORMATION SYSTEMS AND TECHNOLOGIES (CISTI 2015)

Abstract
Learning programming is a complex task that poses significant challenges. Students face different kinds of difficulties at complex levels that traditional teaching/learning methods are nor able to cope with. For this reason, several authors have researched the pedagogical effectiveness of program visualization and animation, and developed some tools. Animation can help students on the analysis and understanding of given programs, and can also guide on the development of new ones. It is very important to give students the opportunity to practice solving programming exercises by themselves. Receiving feedback is essential for knowledge acquisition. New tools arose (especially in the area of programming contests) to allow for the submission of solutions (programs developed by the students) to the problem statements presented by the teacher and to assess them, returning immediately information about the submitted answer. These tools can be incorporated into teaching activities, allowing students to test their work getting immediate feedback. Automatic evaluation systems significantly improve students performance. In this article are shown these two approaches, animation and automatic assessment, and proposed a new pedagogical practice resulting from the combination of both.

2015

Using multiresolution time series motifs to classify urban sounds

Autores
Gomes, EF; Batista, F;

Publicação
International Journal of Software Engineering and its Applications

Abstract
The automatic classification of urban sounds is important for environmental monitoring. In this work we employ SAX-based Multiresolution Motif Discovery to generate features for Urban Sound Classification. Our approach consists in the discovery of relevant frequent motifs in the audio signals and use the frequency of discovered motifs as characterizing attributes. We explore and evaluate different configurations of motif discovery for defining attributes. In the automatic classification step we use a decision tree based algorithm, random forests and SVM. Results obtained are compared with the ones using Mel-Frequency Cepstral Coefficients (MFCC) as features. MFCCs are commonly used in environmental sound analysis, as well as in other sound classification tasks. Experiments were performed on the Urban Sound dataset, which is publicly available. Our results indicate that we can separate difficult pairs of classes (where MFCC fails) using the motif approach for feature construction. © 2015 SERSC.

2015

Classifying Urban Sounds using Time Series Motifs

Autores
Gomes, EF; Batista, F;

Publicação

Abstract

2015

Animation and Automatic Evaluation in Supporting the teaching of Programming

Autores
Tavares, PC; Gomes, EF; Henriques, PR;

Publicação
2015 10TH IBERIAN CONFERENCE ON INFORMATION SYSTEMS AND TECHNOLOGIES (CISTI)

Abstract
Learning programming is a complex task that poses significant challenges. Students face different kinds of difficulties at complex levels that traditional teaching/learning methods are nor able to cope with. For this reason, several authors have researched the pedagogical effectiveness of program visualization and animation, and developed some tools. Animation can help students on the analysis and understanding of given programs, and can also guide on the development of new ones. It is very important to give students the opportunity to practice solving programming exercises by themselves. Receiving feedback is essential for knowledge acquisition. New tools arose ( especially in the area of programming contests) to allow for the submission of solutions ( programs developed by the students) to the problem statements presented by the teacher and to assess them, returning immediately information about the submitted answer. These tools can be incorporated into teaching activities, allowing students to test their work getting immediate feedback. Automatic evaluation systems significantly improve students performance. In this article are shown these two approaches, animation and automatic assessment, and proposed a new pedagogical practice resulting from the combination of both.

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