2015
Authors
Osório, A;
Publication
Operations Research Letters
Abstract
In the present paper we characterize the optimal use of Poisson signals to establish incentives in the "bad" and "good" news models of Abreu et al. (1991). In the former, for small time intervals the signals' quality is high and we observe a "selective" use of information; otherwise there is a "mass" use. In the latter, for small time intervals the signals' quality is low and we observe a "fine" use of information; otherwise there is a "non-selective" use.
2015
Authors
Oliveira, PM; Vrancic, D; Freire, HF;
Publication
CONTROLO'2014 - PROCEEDINGS OF THE 11TH PORTUGUESE CONFERENCE ON AUTOMATIC CONTROL
Abstract
A dual mode control configuration involving open-loop feedforward control to deal with set-point tracking and proportional integrative and derivative control to deal with disturbance rejection is proposed. The feedforward controller is a Posicast pre-filter shaping the reference input using either two or three steps. The switching between the open-loop and closed-loop control is performed automatically. The particle swarm optimization algorithm is deployed as design tool both for the feedforward and PID controller. Simulation results are presented showing the merits of the proposed technique.
2015
Authors
Mohanty, SR; Kishor, N; Ray, PK; Catalao, J;
Publication
2015 IEEE POWER & ENERGY SOCIETY GENERAL MEETING
Abstract
2015
Authors
Pereira, J; Alves, J; Matos, M;
Publication
2015 18TH INTERNATIONAL CONFERENCE ON INTELLIGENT SYSTEM APPLICATION TO POWER SYSTEMS (ISAP)
Abstract
This paper presents a new and efficient methodology for voltage control and network reconfiguration of distribution networks using fuzzy rules, EPSO and graph theory. A simpler representation of the network is built through a graph, were all the network loops are identified, both closed and open loops. This information is incorporated into the EPSO operators to create feasible solutions for the topological problem, avoiding convergence problems and reducing the computational burden. The initial EPSO population is created from the initial feasible solution, using appropriated heuristics to create feasible and possibly better initial solutions. At the same time a heuristic based strategy is used to perform local voltage control actions. Finally a fuzzy inference based algorithm is employed to achieve the optimal transformer and capacitor bank tap position. The proposed methodology was tested in a 13-bus test system, and in a real distribution system with 3200 buses.
2015
Authors
Dashtbozorg, B; Mendonça, AM; Campilho, A;
Publication
COMPUTERS IN BIOLOGY AND MEDICINE
Abstract
Background: The optic disc (OD) centre and boundary are important landmarks in retinal images and are essential for automating the calculation of health biomarkers related with some prevalent systemic disorders, such as diabetes, hypertension, cerebrovascular and cardiovascular diseases. Methods: This paper presents an automatic approach for OD segmentation using a multiresolution sliding band filter (SBF). After the preprocessing phase, a low-resolution SBF is applied on a down-sampled retinal image and the locations of maximal filter response are used for focusing the analysis on a reduced region of interest (ROI). A high-resolution SBF is applied to obtain a set of pixels associated with the maximum response of the SBF, giving a coarse estimation of the OD boundary, which is regularized using a smoothing algorithm. Results: Our results are compared with manually extracted boundaries from public databases (ONHSD, MESSIDOR and INSPIRE-AVR datasets) outperforming recent approaches for OD segmentation. For the ONHSD, 44% of the results are classified as Excellent, while the remaining images are distributed between the Good (47%) and Fair (9%) categories. An average overlapping area of 83%, 89% and 85% is achieved for the images in ONHSD, MESSIDOR and INSPIR-AVR datasets, respectively, when comparing with the manually delineated OD regions. Discussion: The evaluation results on the images of three datasets demonstrate the better performance of the proposed method compared to recently published OD segmentation approaches and prove the independence of this method when from changes in image characteristics such as size, quality and camera field of view.
2015
Authors
Ana Filipa Pinheiro Sequeira;
Publication
Abstract
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