2010
Authors
Matias, L; Gama, J; Moreira, JM; de Sousa, JF;
Publication
13th International IEEE Conference on Intelligent Transportation Systems, Funchal, Madeira, Portugal, 19-22 September 2010
Abstract
It is well known that the definition of bus schedules is critical for the service reliability of public transports. Several proposals have been suggested, using data from Automatic Vehicle Location (AVL) systems, in order to enhance the reliability of public transports. In this paper we study the optimum number of schedules and the days covered by each one of them, in order to increase reliability. We use the Dynamic Time Warping distance in order to calculate the similarities between two different dimensioned irregularly spaced data sequences before the use of data clustering techniques. The application of this methodology with the K-Means for a specific bus route demonstrated that a new schedule for the weekends in non-scholar periods could be considered due to its distinct profile from the remaining days. For future work, we propose to apply this methodology to larger data sets in time and in number, corresponding to different bus routes, in order to find a consensual cluster between all the routes. ©2010 IEEE.
2010
Authors
Severo, Milton; Gama, Joao;
Publication
Ubiquitous Knowledge Discovery - Challenges, Techniques, Applications
Abstract
In most challenging applications learning algorithms act in dynamic environments where the data is collected over time. A desirable property of these algorithms is the ability of incremental incorporating new data in the actual decision model. Several incremental learning algorithms have been proposed. However most of them make the assumption that the examples are drawn from a stationary distribution [14]. The aim of this study is to present a detection system (DSKC) for regression problems. The system is modular and works as a post-processor of a regressor. It is composed by a regression predictor, a Kalman filter and a Cumulative Sum of Recursive Residual (CUSUM) change detector. The system continuously monitors the error of the regression model. A significant increase of the error is interpreted as a change in the distribution that generates the examples over time. When a change is detected, the actual regression model is deleted and a new one is constructed. In this paper we tested DSKC with a set of three artificial experiments, and two real-world datasets: a Physiological dataset and a clinic dataset of sleep apnoea. Sleep apnoea is a common disorder characterized by periods of breathing cessation (apnoea) and periods of reduced breathing (hypopnea) [7]. This is a real-world application where the goal is to detect changes in the signals that monitor breathing. The experimental results showed that the system detected changes fast and with high probability. The results also showed that the system is robust to false alarms and can be applied with efficiency to problems where the information is available over time. © 2010 Springer-Verlag.
2010
Authors
Gama, J; Cornuéjols, A;
Publication
Ubiquitous Knowledge Discovery - Challenges, Techniques, Applications
Abstract
In the introduction it was argued that ubiquitous knowledge discovery systems have to be able to sense their environment and receive data from other devices, to adapt continuously to changing environmental conditions (including their own condition) and evolving user habits and need be capable of predictive self-diagnosis. In the last chapter, resource constraints arising from ubiquitous environments have been discussed in some detail. It has been argued that algorithms have to be resource-aware because of real-time constraints and of limited computing and battery power as well as communication resources. © 2010 Springer-Verlag.
2010
Authors
Gaber, MM; Vatsavai, RR; Omitaomu, OA; Gama, J; Chawla, NV; Ganguly, AR;
Publication
Lecture Notes in Computer Science
Abstract
2010
Authors
Shultz, TR; Fahlman, SE; Craw, S; Andritsos, P; Tsaparas, P; Silva, R; Drummond, C; Ling, CX; Sheng, VS; Drummond, C; Lanzi, PL; Gama, J; Wiegand, RP; Sen, P; Namata, G; Bilgic, M; Getoor, L; He, J; Jain, S; Stephan, F; Jain, S; Stephan, F; Sammut, C; Harries, M; Sammut, C; Ting, KM; Pfahringer, B; Case, J; Jain, S; Wagstaff, KL; Nijssen, S; Wirth, A; Ling, CX; Sheng, VS; Zhang, X; Sammut, C; Cancedda, N; Renders, J; Michelucci, P; Oblinger, D; Keogh, E; Mueen, A;
Publication
Encyclopedia of Machine Learning
Abstract
2010
Authors
Kosina, P; Gama, J; Sebastiao, R;
Publication
ECAI 2010 - 19TH EUROPEAN CONFERENCE ON ARTIFICIAL INTELLIGENCE
Abstract
Concept drift in data is usually considered only as abrupt or gradual thus referring to the speed of change. Such simple distinguishing by speed is sufficient for most of the problems, but there might be situations for which a finer representation would be of use. This paper studies further the phenomenon of concept drift and introduces a simple measure which is relevant to the speed and amount of change between different concepts.
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