2008
Autores
Leitao, P; Restivo, FJ;
Publicação
IEEE TRANSACTIONS ON SYSTEMS MAN AND CYBERNETICS PART C-APPLICATIONS AND REVIEWS
Abstract
Answering to the need to have innovative manufacturing control systems tailored to the current economical, technological, and customer trends, where dynamic and volatile environments prevail, adaptive holonic control architecture (ADACOR) aims to increase the agility and reconfigurability of the production system, contributing for the improvement of the enterprise competitiveness when it works in dynamic and volatile environments. The paper describes the implementation and experimental validation of an ADACOR-based holonic manufacturing control system in a real flexible manufacturing system, using multiagent systems technology. The results extracted from a set of experimental tests allowed to verify the correctness, applicability, and merits of the ADACOR concepts and also contribute to prove the applicability of multiagent systems in industrial environments.
2008
Autores
Rodrigues, RB; Mendes, VMF; Catalao, JPS; Correia, S; Prior, V; Aguado, M;
Publicação
2008 IEEE POWER & ENERGY SOCIETY GENERAL MEETING, VOLS 1-11
Abstract
This paper presents a characterization of the wind energy in Portugal in what regards: the installed power capacity, the capacity under construction, and the geographical location of wind turbines. The Portuguese Lightning Location System (LLS) is described, and new experimental and analytical results are presented. Analysis about geographical and time distribution of cloud-to-ground (CG) strikes and accumulative probability of peak current are carried out. Also, new ground flash density (GFD) maps are presented. Hence, the paper improves the knowledge about the lightning activity in Portugal, allowing the enhancement of risk analysis studies.
2008
Autores
Gabriel, RC; Abrantes, J; Granata, K; Bulas Cruz, J; Melo Pinto, P; Filipe, V;
Publicação
PHYSICAL THERAPY IN SPORT
Abstract
Objectives: To characterize and compare dynamic joint stiffness (DJS) of the ankle in the sagittal plane during natural cadence walking in both genders. Design: Observation, cross-sectional and matched pairs. Participants: Twenty-one males (mean age = 27 +/- 4.2 years) and 18 females (mean age = 22.9 +/- 4.1 years). Setting: Laboratory at the University de Tras-os-Montes and Alto Douro. The DJS of the ankle was assessed while participants performed barefoot walking at a natural cadence, was measured using a force platform (1000 Hz), and synchronized with a high-speed camera (200 Hz). Main outcome measures: DJS of the ankle in males and females was calculated in two sub-phases (the second and the fourth sub-phases) of the stance phase. The Wilcoxon non-parametric matched-pairs test and the Mann-Whitney U non-parametric test were used to analyse difference of DJS of the ankle within and between the groups with p <= 0.05 regarded as significant. Results: Male and female participants demonstrated significantly (p<0.005) less DJS during the second sub-phase. DJS was not significantly (p>0.063) different between females (0.0511 N m/kg/degrees) and males (0.0596 N m/kg/degrees) during the second sub-phase. DJS was significantly (p<0.001) higher in males (0.0844 N m/kg/degrees) than females (0.0691 N m/kg/degrees) during the fourth sub-phase. Conclusions: Gender-specific DJS characteristics demonstrated by females in this study may be used in preventative training programs designed to promote a greater ability to use contractile components to produce mechanical energy through the ankle.
2008
Autores
Cardoso, JMP; Diniz, PC;
Publicação
INTERNATIONAL JOURNAL OF ELECTRONICS
Abstract
Three articles focusing on interesting architectural features and/or execution techniques which configurable architectures make more accessible are discussed. The Applied Reconfigurable Computing (ARC) workshop series has been devoted to addressing the role of software programmers and hardware designers in implementing configurable and reconfigurable architectures while still recognizing the value of configurable computing basic techniques and application areas. The first article, by Wu, Kanstein, Madsen and Berekovic, describes the application of multithreading to a coarse-grain reconfigurable architecture. The second article by Chikhi, Derrien, Noumsi and Quinton, is devoted to a specific architectural feature, the inclusion of FLASH memory to facilitate the implementation of image-based algorithms, an application that matches very well with FPGA configurable technology. Finally, a third article in this track by Hur, Wong and Vassiliadis, explores the use of point-to-point interconnects in a contemporary FPGA.
2008
Autores
Melicio, R; Mendes, VMF; Catalao, JPS;
Publicação
2008 IEEE MEDITERRANEAN ELECTROTECHNICAL CONFERENCE, VOLS 1 AND 2
Abstract
This paper is concerned with modeling and Simulation of a wind energy system with different topologies for the power converters, namely a matrix converter and a multilevel converter. We use pulse modulation by space vector modulation associated with sliding mode for controlling the converters, and we introduce power factor control at the output of the converters. Finally, we present the electric behavior for the power and the current at the output of the converters.
2008
Autores
Lima, L; Vilela, JP; Barros, J; Medard, M;
Publicação
2008 INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY AND ITS APPLICATIONS, VOLS 1-3
Abstract
We consider the issue of confidentiality in multicast network coding, by assuming that the encoding matrices, based upon variants of random linear network coding, are given only to the source and sinks. Based on this assumption, we provide a characterization of the mutual information between the encoded data and the two elements that can lead to information disclosure: the matrices of random coefficients and, naturally, the original data itself. Our results, some of which hold even with finite block lengths, show that, predicated on optimal source-coding, information-theoretic security is achievable for any field size without loss in terms of decoding probability. It follows that protecting the encoding matrix is generally sufficient to ensure confidentiality of network coded data.
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