Abstract
Long-period fiber gratings (LPGs) have been inscribed in nitrogen-doped fibers by electrical arc discharge. The influence of drawing tension as well as external load applied during arc discharge on coupling strength has been investigated. The influence of drawing tension on the grating's coupling strength is found to be negligible, whereas the coupling strength increases considerably with external load. Tomographic stress profiles of the fiber have been recorded before and after electric arc discharge. The axial stress modulation in the core region of the grating was found to be smaller than 10 MPa and is thus too small to be the dominating mechanism for grating formation.

Abstract

Abstract
This paper describes the design of a Power System Stabilizer synthesized by a static Artificial Neural Network. The patterns used to train the neural network are sets of controller parameters, previously calculated for several system operation points using a pole-shifting method. This neural network stabilizer then operates, in a gain-scheduling scheme, in accordance with the values of active and reactive powers furnished by the generator to the power system, but with soft transition variations of the controller parameters. The trained neural network presents, as its main characteristic, almost uniform values for all the stabilizer parameters when the system synchronous machine is generating reactive power, but these same parameters suffer great variations when the machine is absorbing reactive power. Simulation tests presented show very good performance for the proposed Neural PSS, when compared with a fixed-parameter stabilizer, corroborating the main characteristic of the proposed stabilizer. (C) 2005 Published by Elsevier Ltd.

Abstract
In this paper we address the problem of tracking feature points along image sequences. To analyze the undergoing movement we use a common approach based on Kalman filtering which performs the estimation and correction of the feature point's movement in every image frame. The criterion proposed to establish correspondences, between the group of estimates in each image and the new data to include, minimizes the global matching cost based on the Mahalanobis distance. In this paper, along with the movement tracking, we use a management model which is able to deal with the occlusion and appearance of feature points and allows objects tracking in long sequences. We also present some experimental results obtained that validate our approach.

Abstract
The coastline of Portugal is periodically surveyed by aircraft and the photographs acquired, usually at 1:8000 scale, are used for coastal protection studies. The air photo surveys are expensive and there would be great benefits if they could be replaced by processed images from Earth Observation Satellites. This paper presents the results of an ongoing project, which aims to evaluate the applicability of passive satellite images for coastal protection studies. Images from Landsat TM, SPOT HRVIR and ASTER were used. The initial visual inspection of these images was very encouraging. Two lines of work are currently being pursued - a quantitative and an image exploration approach. The first attempts to estimate the amount of sediments present in the various areas around the sea-breaking zone, by calibrating and atmospherically correcting the satellite images, and to use an established relationship between the amount of suspended sediments and the seawater reflectance. The second approach is to use unsupervised classification and data clustering algorithms to automatically identify different areas in the sea-breaking zone. The current status of each line of work is described and the plans for future work discussed.

Abstract
An agglomerative hierarchical clustering method, which uses both spectral and spatial information for the aggregation decision, is proposed here. The method is suitable for large multispectral images, provided that an unsupervised classification is previously applied. The method is tested on a synthetic image and on a satellite image of the coastal zone.