2014
Authors
Jacobs, B; Silva, A;
Publication
Horizons of the Mind. A Tribute to Prakash Panangaden - Essays Dedicated to Prakash Panangaden on the Occasion of His 60th Birthday
Abstract
2014
Authors
Madureira, A; Cunha, B; Pereira, JP; Pereira, I; Gomes, S;
Publication
2014 SIXTH WORLD CONGRESS ON NATURE AND BIOLOGICALLY INSPIRED COMPUTING (NABIC)
Abstract
User modeling and user adaptive interaction research areas are becoming crucial applied issues to understand and support users as they interact with technology. Modeling the decisions to be made and the constraints placed by market globalization in a way that can address the needs of all stakeholders has been a long time area of academic and industrial research, mainly for Planning, Scheduling, and Strategic decision making areas. Business analysts, developers, and organizations involved in all phases of the business value chain have requirements for applied business insight through modeling. In this paper, an architecture for user modeling on Intelligent and Adaptive Scheduling System is proposed.
2014
Authors
Resende, FO; Vasconcelos, MH; Pecas Lopes, JAP;
Publication
2014 POWER SYSTEMS COMPUTATION CONFERENCE (PSCC)
Abstract
Using Voltage Source Converter (VSC) based High Voltage Direct Current (HVDC) technologies, in a Multi-terminal dc (MTDC) system, has been envisaged as an attractive solution for connecting the large offshore wind farms that have been planned to meet the EU renewable energy targets. The control and operation of VSC-HVDC technologies comprise a number of challenging tasks, aiming to assure an effective integration of MTDC systems in ac transmission systems. Stability studies play a key role within this framework. Among them, small signal stability analysis is required. Therefore, in this paper, modal analysis is performed for assessing small signal stability, in terms of the electromechanical modes of oscillation, considering the combined AC-MTDC system. Also, this paper evaluates the interest of installing classical Power Systems Stabilizer (PSS) in the onshore VSC stations for providing additional damping to the electromechanical modes of oscillation. Simultaneous tuning is performed for adjusting the parameters of these PSS based controllers. For this purpose, an optimization based approach exploiting Evolutionary Particle Swarm Optimization (EPSO) is proposed. Modal analysis and time domain simulations are performed to evaluate the effectiveness of the proposed solutions.
2014
Authors
T, HF; Gama, J;
Publication
Progress in AI
Abstract
Event labeling is the process of marking events in unlabeled data. Traditionally, this is done by involving one or more human experts through an expensive and timeconsuming task. In this article we propose an event labeling system relying on an ensemble of detectors and background knowledge. The target data are the usage log of a real bike sharing system. We first label events in the data and then evaluate the performance of the ensemble and individual detectors on the labeled data set using ROC analysis and static evaluation metrics in the absence and presence of background knowledge. Our results show that when there is no access to human experts, the proposed approach can be an effective alternative for labeling events. In addition to the main proposal, we conduct a comparative study regarding the various predictive models performance, semi-supervised and unsupervised approaches, train data scale, time series filtering methods, online and offline predictive models, and distance functions in measuring time series similarity. © Springer-Verlag Berlin Heidelberg 2013.
2014
Authors
Sillero, N; Goncalves Seco, L;
Publication
INTERNATIONAL JOURNAL OF GEOGRAPHICAL INFORMATION SCIENCE
Abstract
The analysis of the spatial structure of animal communities requires spatial data to determine the distribution of individuals and their limiting factors. New technologies like very precise GPS as well as satellite imagery and aerial photographs of very high spatial resolution are now available. Data from airborne LiDAR (Light Detection and Ranging) sensors can provide digital models of ground and vegetation surfaces with pixel sizes of less than 1m. We present the first study in terrestrial herpetology using LiDAR data. We aim to identify the spatial patterns of a community of four species of lizards (Lacerta schreiberi, Timon lepidus, Podarcis bocagei, and P. hispanica), and to determine how the habitat is influencing the distribution of the species spatially. The study area is located in Northern Portugal. The position of each lizard was recorded during 16 surveys of 1 h with a very precise GPS (error<1 m). LiDAR data provided digital models of surface, terrain, and normalised height. From these data, we derived slope, ruggedness, orientation, and hill-shading variables. We applied spatial statistics to determine the spatial structure of the community. We computed Maxent ecological niche models to determine the importance of environmental variables. The community and its species presented a clustered distribution. We identified 14 clusters, composed of 1-3 species. Species records showed two distribution patterns, with clusters associated with steep and flat areas. Cluster outliers had the same patterns. Juveniles and subadults were associated with areas of low quality, while sexes used space in similar ways. Maxent models identified suitable habitats across the study area for two species and in the flat areas for the other two species. LiDAR allowed us to understand the local distributions of a lizard community. Remotely sensed data and LiDAR are giving new insights into the study of species ecology. Images of higher spatial resolutions are necessary to map important factors such as refuges.
2014
Authors
Pinto, AA; Parreira, T;
Publication
Springer Proceedings in Mathematics and Statistics
Abstract
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