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Publicações

2017

Mining Moodle Logs for Grade Prediction: A methodology walk-through

Autores
Figueira, A;

Publicação
Proceedings of the 5th International Conference on Technological Ecosystems for Enhancing Multiculturality, TEEM 2017, Cádiz, Spain, October 18 - 20, 2017

Abstract
Research concerning mining data from learning management systems have been consistently been appearing in the literature. However, in many situations there is not a clear path on the data mining procedures that lead to solid conclusions. Therefore, many studies result in ad-hoc conclusions with insufficient generalization capabilities. In this article, we describe a methodology and report our findings in an experiment which one online course which involved more than 150 students. We used the Moodle LMS during the period of one academic semester, collecting all the interactions between the students and the system. These data scales up to more than 33K records of interactions where we applied data mining tools following the procedure for data extraction, cleaning, feature identification and preparation. We then proceeded to the creation of automatic learning models based on decision trees, we assessed the models and validate the results by assessing the accuracy of the predictions using traditional metrics and draw our conclusions on the validity of the process and possible alternatives1. © 2017 Association for Computing Machinery.

2017

Convolutional bag of words for diabetic retinopathy detection from eye fundus images

Autores
Costa, Pedro; Campilho, Aurelio;

Publicação
IPSJ Trans. Computer Vision and Applications

Abstract

2017

Electrical Energy Consumption Forecast Using Support Vector Machines

Autores
Vinagre, E; Pinto, T; Ramos, S; Vale, Z; Corchado, JM;

Publicação
Proceedings - International Workshop on Database and Expert Systems Applications, DEXA

Abstract
Smart Grid (SG) concept is defined as an electricity network operated intelligently to integrate the behavior and actions of all energy resources connected to the network to ensure efficient, sustainable, economic and secure supply of electricity. This concept emerged in recent decades not only for economic reasons but also ecological and even political. SG have been the subject of major studies and investments and continues to represent an area of enormous challenges. Some of the problems of intelligent systems connected to the managed SG are: the real-time processing optimization algorithms and demand response programs; and more accurate predictions in the management of production and consumption. This paper presents a case study for evaluating the performance and accuracy of energy consumption forecast with use of SVM (Support Vector Machines) in different frameworks. © 2016 IEEE.

2017

On scaling dynamic programming problems with a multithreaded tabling, Prolog system

Autores
Areias, M; Rocha, R;

Publicação
JOURNAL OF SYSTEMS AND SOFTWARE

Abstract
Tabling is a powerful implementation technique that improves the declarativeness and expressiveness of traditional Prolog systems in dealing with recursion and redundant computations. It can be viewed as a natural tool to implement dynamic programming problems, where a general recursive strategy divides a problem in simple sub-problems that are often the same. When tabling is combined with multithreading, we have the best of both worlds, since we can exploit the combination of higher declarative semantics with higher procedural control. However, at the engine level, such combination for dynamic programming problems is very difficult to exploit in order to achieve execution scalability as we increase the number of running threads. In this work, we focus on two well-known dynamic programming problems, the Knapsack and the Longest Common Subsequence problems, and we discuss how we were able to scale their execution by using the multithreaded tabling engine of the Yap Prolog system. To the best of our knowledge, this is the first work showing a Prolog system to be able to scale the execution of multithreaded dynamic programming problems. Our experiments also show that our system can achieve comparable or even better speedup results than other parallel implementations of the same problems.

2017

Automatic and semi-automatic approaches for arteriolar-to-venular computation in retinal photographs

Autores
Mendonca, AM; Remeseiro, B; Dashtbozorg, B; Campilho, A;

Publicação
MEDICAL IMAGING 2017: COMPUTER-AIDED DIAGNOSIS

Abstract
The Arteriolar-to-Venular Ratio (AVR) is a popular dimensionless measure which allows the assessment of patients' condition for the early diagnosis of different diseases, including hypertension and diabetic retinopathy. This paper presents two new approaches for AVR computation in retinal photographs which include a sequence of automated processing steps: vessel segmentation, caliber measurement, optic disc segmentation, artery/vein classification, region of interest delineation, and AVR calculation. Both approaches have been tested on the INSPIRE-AVR dataset, and compared with a ground-truth provided by two medical specialists. The obtained results demonstrate the reliability of the fully automatic approach which provides AVR ratios very similar to at least one of the observers. Furthermore, the semi-automatic approach, which includes the manual modification of the artery/vein classification if needed, allows to significantly reduce the error to a level below the human error.

2017

Progress in Artificial Intelligence

Autores
Oliveira, E; Gama, J; Vale, Z; Lopes Cardoso, H;

Publicação
Lecture Notes in Computer Science

Abstract

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