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Publicações

2015

Fast Algorithm Selection Using Learning Curves

Autores
van Rijn, JN; Abdulrahman, SM; Brazdil, P; Vanschoren, J;

Publicação
Advances in Intelligent Data Analysis XIV

Abstract
One of the challenges in Machine Learning to find a classifier and parameter settings that work well on a given dataset. Evaluating all possible combinations typically takes too much time, hence many solutions have been proposed that attempt to predict which classifiers are most promising to try. As the first recommended classifier is not always the correct choice, multiple recommendations should be made, making this a ranking problem rather than a classification problem. Even though this is a well studied problem, there is currently no good way of evaluating such rankings. We advocate the use of Loss Time Curves, as used in the optimization literature. These visualize the amount of budget (time) needed to converge to a acceptable solution. We also investigate a method that utilizes the measured performances of classifiers on small samples of data to make such recommendation, and adapt it so that it works well in Loss Time space. Experimental results show that this method converges extremely fast to an acceptable solution.

2015

Modeling lot sizing and scheduling in practice

Autores
Guimarães, L; Figueira, G; Amorim, P; Almada Lobo, B;

Publicação
Operations Research and Big Data: IO2015-XVII Congress of Portuguese Association of Operational Research (APDIO)

Abstract
Lot sizing and scheduling by mixed integer programming has been a hot research topic in the last 20 years. Researchers have been trying to develop stronger formulations, as well as to incorporate real-world requirements from different applications. In this paper we illustrate some of these requirements and show howmodels have been adapted and extended. Motivation comes from different industries, especially from process and fast moving consumer goods industries.

2015

Data mining approach to support the generation of Realistic Scenarios for multi-agent simulation of electricity markets

Autores
Teixeira, B; Silva, F; Pinto, T; Praca, I; Santos, G; Vale, Z;

Publicação
IEEE SSCI 2014 - 2014 IEEE Symposium Series on Computational Intelligence - IA 2014: 2014 IEEE Symposium on Intelligent Agents, Proceedings

Abstract
This paper presents the Realistic Scenarios Generator (RealScen), a tool that processes data from real electricity markets to generate realistic scenarios that enable the modeling of electricity market players' characteristics and strategic behavior. The proposed tool provides significant advantages to the decision making process in an electricity market environment, especially when coupled with a multi-agent electricity markets simulator. The generation of realistic scenarios is performed using mechanisms for intelligent data analysis, which are based on artificial intelligence and data mining algorithms. These techniques allow the study of realistic scenarios, adapted to the existing markets, and improve the representation of market entities as software agents, enabling a detailed modeling of their profiles and strategies. This work contributes significantly to the understanding of the interactions between the entities acting in electricity markets by increasing the capability and realism of market simulations. © 2014 IEEE.

2015

Generic System for Human-Computer Gesture Interaction: Applications on Sign Language Recognition and Robotic Soccer Refereeing

Autores
Trigueiros, P; Ribeiro, F; Reis, LP;

Publicação
JOURNAL OF INTELLIGENT & ROBOTIC SYSTEMS

Abstract
Hand gestures are a powerful way for human communication, with lots of potential applications in the area of human computer interaction. Vision-based hand gesture recognition techniques have many advantages compared with traditional devices, giving users a simpler and more natural way to communicate with electronic devices. This work proposes a generic system architecture based in computer vision and machine learning, able to be used with any interface for real-time human-machine interaction. Its novelty is the integration of different tools for gesture spotting and the proposed solution is mainly composed of three modules: a pre-processing and hand segmentation module, a static gesture interface module and a dynamic gesture interface module. The experiments showed that the core of vision-based interaction systems could be the same for all applications and thus facilitate the implementation. For hand posture recognition, a SVM (Support Vector Machine) model was trained with a centroid distance dataset composed of 2170 records, able to achieve a final accuracy of 99.4 %. For dynamic gestures, an HMM (Hidden Markov Model) model was trained for each one of the defined gestures that the system should recognize with a final average accuracy of 93.7 %. The datasets were built from four different users with a total of 25 gestures per user, totalling 1100 records for model construction. The proposed solution has the advantage of being generic enough with the trained models able to work in real-time, allowing its application in a wide range of human-machine applications. To validate the proposed framework two applications were implemented. The first one is a real-time system able to interpret the Portuguese Sign Language. The second one is an online system able to help a robotic soccer game referee judge a game in real-time.

2015

Distributed intelligent management of microgrids using a multi-agent simulation platform

Autores
Gomes, L; Pinto, T; Faria, P; Vale, Z;

Publicação
IEEE SSCI 2014 - 2014 IEEE Symposium Series on Computational Intelligence - IA 2014: 2014 IEEE Symposium on Intelligent Agents, Proceedings

Abstract
Multi-agent approaches have been widely used to model complex systems of distributed nature with a large amount of interactions between the involved entities. Power systems are a reference case, mainly due to the increasing use of distributed energy sources, largely based on renewable sources, which have potentiated huge changes in the power systems' sector. Dealing with such a large scale integration of intermittent generation sources led to the emergence of several new players, as well as the development of new paradigms, such as the microgrid concept, and the evolution of demand response programs, which potentiate the active participation of consumers. This paper presents a multi-agent based simulation platform which models a microgrid environment, considering several different types of simulated players. These players interact with real physical installations, creating a realistic simulation environment with results that can be observed directly in the reality. A case study is presented considering players' responses to a demand response event, resulting in an intelligent increase of consumption in order to face the wind generation surplus. © 2014 IEEE.

2015

Serious Games for Cognitive Rehabilitation Forms of interaction and Social Dimension

Autores
Rocha, R; Reis, LP; Rego, PA; Moreira, PM;

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

Abstract
Rehabilitation processes follow, as a rule, intensive training programs, composed of repetitive and monotonous tasks for patients. The introduction of serious games in these processes can help in motivating patients, increasing their interest in the exercises to perform. These games should be set taking into account characteristics that are able to stimulate and train cognitive functions as well as features that require some kind of motor activity in order to stimulate and attract patients' attention. This article presents a literature review on serious games for cognitive rehabilitation and a set of characteristics that are considered important for serious game development in this area which include the use of natural and multimodal interfaces and a social dimension such as collaboration, competition and the concept of handicap.

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