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Publications

2005

Strategies to parallelize ILP systems

Authors
Fonseca, NA; Silva, F; Camacho, R;

Publication
INDUCTIVE LOGIC PROGRAMMING, PROCEEDINGS

Abstract
It is well known by Inductive Logic Programming (ILP) practioners that ILP systems usually take a long time to find valuable models (theories). The problem is specially critical for large datasets, preventing ILP systems to scale up to larger applications. One approach to reduce the execution time has been the parallelization of ILP systems. In this paper we overview the state-of-the-art on parallel ILP implementations and present work on the evaluation of some major parallelization strategies for ILP. Conclusions about the applicability of each strategy are presented.

2005

Low-loss splice in a microstructured fibre using a conventional fusion splicer

Authors
Frazao, O; Carvalho, JP; Salgado, HM;

Publication
MICROWAVE AND OPTICAL TECHNOLOGY LETTERS

Abstract
A simple splice technique to fuse a SMF-28 (TM) and a microstructured fibre using a conventional electric-are splicer is presented. The technique consists in applying the electric arc in the SMF-28 (TM) region. The fusion-loss dependence with arc duration for constant fusion power is also investigated. A splice loss of 0.25 dB is obtained with high rtproducibility. (c) 2005 Wiley Periodicals, Inc.

2005

Fuzzy inference systems applied to LV substation load estimation

Authors
Konjic, T; Miranda, V; Kapetanovic, I;

Publication
IEEE TRANSACTIONS ON POWER SYSTEMS

Abstract
This paper describes a system for estimating load curves at low-voltage (LV) substations. The system is built by the aggregation of individual fuzzy inference systems of the Takagi-Sugeno type. The model was developed from actual measurements forming a base of raw data of consumer behavior. This database allowed one to build large test and,training sets of simulated LV substations, which led to the development of the fuzzy system. The results are compared in terms of accuracy with the ones obtained with a previous artificial neural network approach, with better performance.

2005

Chirped fibre Bragg grating based multiplexer and demultiplexer for DWDM applications

Authors
Romero, R; Frazao, O; Floreani, F; Zhang, L; Marques, PVS; Salgado, HM;

Publication
OPTICS AND LASERS IN ENGINEERING

Abstract
A multiplexer/demultiplexer for 100GHz channel spacing based on chirped fibre Bragg gratings with different bandwidths and optical circulators is presented. The spectral characteristics, specifications and operation of these passive devices are described, showing its potential use in dense wavelength division multiplexing (DWDM) applications.

2005

Difference equations for the higher order moments and cumulants of the INAR(p) model

Authors
Silva, ME; Oliveira, VL;

Publication
JOURNAL OF TIME SERIES ANALYSIS

Abstract
Here we obtain difference equations for the higher order moments and cumulants of a time series {X-t} satisfying an INAR(p) model. These equations are similar to the difference equations for the higher order moments and cumulants of the bilinear time series model. We obtain the spectral and bispectral density functions for the INAR(p) process in state-space form, thus characterizing it in the frequency domain. We consider a frequency domain method - the Whittle criterion - to estimate the parameters of the INAR(p) model and illustrate it with the series of the number of epilepsy seizures of a patient.

2005

Optical fiber communications: Recent contributions in photonic device technology

Authors
Carvalho, JP; Romero, R; Melo, M; Gomes, LA; Frazao, O; Marques, MB; Salgado, HM;

Publication
FIBER AND INTEGRATED OPTICS

Abstract
The current status of the research and development as well as the recent contributions in optical communications at INESC Porto is reviewed. This review includes all the work carried out in the last few years in optical fiber communications, namely the development of passive and active optical devices. Some of the passive structures that have been studied and developed are: add-drop multiplexers, multiplexer/ demultiplexer based on Bragg grating technology, dispersion compensators, and optical cross-connects. Active photonic devices such as wavelength converters, fiber lasers, and fiber amplifiers have also been studied. New ideas are being continuously developed and tested.

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