2017
Authors
Nogueira, AR; Ferreira, CA; Gama, J;
Publication
Foundations of Intelligent Systems - 23rd International Symposium, ISMIS 2017, Warsaw, Poland, June 26-29, 2017, Proceedings
Abstract
This work aims to help in the correct and early diagnosis of the acute kidney injury, through the application of data mining techniques. The main goal is to be implemented in Intensive Care Units (ICUs) as an alarm system, to assist health professionals in the diagnosis of this disease. These techniques will predict the future state of the patients, based on his current medical state and the type of ICU. Through the comparison of three different approaches (Markov Chain Model, Markov Chain Model ICU Specialists and Random Forest), we came to the conclusion that the best method is the Markov Chain Model ICU Specialists. © Springer International Publishing AG 2017.
2017
Authors
Sarmento, RP; Cordeiro, M; Brazdil, P; Gama, J;
Publication
Complex Networks & Their Applications VI - Proceedings of Complex Networks 2017 (The Sixth International Conference on Complex Networks and Their Applications), COMPLEX NETWORKS 2017, Lyon, France, November 29 - December 1, 2017.
Abstract
Social Network Analysis (SNA) is an important research area. It originated in sociology but has spread to other areas of research, including anthropology, biology, information science, organizational studies, political science, and computer science. This has stimulated research on how to support SNA with the development of new algorithms. One of the critical areas involves calculation of different centrality measures. The challenge is how to do this fast, as many increasingly larger datasets are available. Our contribution is an incremental version of the Laplacian Centrality measure that can be applied not only to large graphs but also to dynamically changing networks. We have conducted several tests with different types of evolving networks. We show that our incremental version can process a given large network, faster than the corresponding batch version in both incremental and full dynamic network setups. © Springer International Publishing AG 2018.
2017
Authors
Nosratabadi, HE; Fanaee T, H; Gama, J;
Publication
PROGRESS IN ARTIFICIAL INTELLIGENCE (EPIA 2017)
Abstract
Mobility mining has lots of applications in urban planning and transportation systems. In particular, extracting mobility patterns enables service providers to have a global insight about the mobility behaviors which consequently leads to providing better services to the citizens. In the recent years several data mining techniques have been presented to tackle this problem. These methods usually are either spatial extension of temporal methods or temporal extension of spatial methods. However, still a framework that can keep the natural structure of mobility data has not been considered. Non-negative tensor factorizations (NNTF) have shown great applications in topic modelling and pattern recognition. However, unfortunately their usefulness in mobility mining is less explored. In this paper we propose a new mobility pattern mining framework based on a recent non-negative tensor model called BetaNTF. We also present a new approach based on interpretability concept for determination of number of components in the tensor rank selection process. We later demonstrate some meaningful mobility patterns extracted with the proposed method from bike sharing network mobility data in Boston, USA.
2017
Authors
Cardoso, DO; Franca, FMG; Gama, J;
Publication
NEW GENERATION COMPUTING
Abstract
Clustering is a powerful and versatile tool for knowledge discovery, able to provide a valuable information for data analysis in various domains. To perform this task based on streaming data is quite challenging: outdated knowledge needs to be disposed while the current knowledge is obtained from fresh data; since data are continuously flowing, strict efficiency constraints have to be met. This paper presents WCDS, an approach to this problem based on the WiSARD artificial neural network model. This model already had useful characteristics as inherent incremental learning capability and patent functioning speed. These were combined with novel features as an adaptive countermeasure to cluster imbalance, a mechanism to discard expired data, and offline clustering based on a pairwise similarity measure for WiSARD discriminators. In an insightful experimental evaluation, the proposed system had an excellent performance according to multiple quality standards. This supports its applicability for the analysis of data streams.
2017
Authors
Cardoso, DO; Gama, J; Franca, FMG;
Publication
MACHINE LEARNING
Abstract
Open set recognition is a classification-like task. It is accomplished not only by the identification of observations which belong to targeted classes (i.e., the classes among those represented in the training sample which should be later recognized) but also by the rejection of inputs from other classes in the problem domain. The need for proper handling of elements of classes beyond those of interest is frequently ignored, even in works found in the literature. This leads to the improper development of learning systems, which may obtain misleading results when evaluated in their test beds, consequently failing to keep the performance level while facing some real challenge. The adaptation of a classifier for open set recognition is not always possible: the probabilistic premises most of them are built upon are not valid in a open-set setting. Still, this paper details how this was realized for WiSARD a weightless artificial neural network model. Such achievement was based on an elaborate distance-like computation this model provides and the definition of rejection thresholds during training. The proposed methodology was tested through a collection of experiments, with distinct backgrounds and goals. The results obtained confirm the usefulness of this tool for open set recognition.
2017
Authors
Sebastião, R; Gama, J; Mendonça, T;
Publication
I. J. Data Science and Analytics
Abstract
The remarkable number of real applications under
dynamic scenarios is driving a novel ability to generate and
gatherinformation.Nowadays,amassiveamountofinforma-
tion is generated at a high-speed rate, known as data streams.
Moreover, data are collected under evolving environments.
Due to memory restrictions, data must be promptly processed
and discarded immediately. Therefore, dealing with evolving
data streams raises two main questions: (i) how to remember
discarded data? and (ii) how to forget outdated data? To main-
tain an updated representation of the time-evolving data, this
paper proposes fading histograms. Regarding the dynamics
of nature, changes in data are detected through a windowing
scheme that compares data distributions computed by the
fading histograms: the adaptive cumulative windows model
(ACWM). The online monitoring of the distance between
data distributions is evaluated using a dissimilarity measure
based on the asymmetry of the Kullback–Leibler divergence.The experimental results support the ability of fading his-
tograms in providing an updated representation of data. Such
property works in favor of detecting distribution changes
with smaller detection delay time when compared with stan-
dard histograms. With respect to the detection of concept
changes, the ACWM is compared with 3 known algorithms
taken from the literature, using artificial data and using pub-
lic data sets, presenting better results. Furthermore, we the
proposed method was extended for multidimensional and the
experiments performed show the ability of the ACWM for
detecting distribution changes in these settings.
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