Abstract
This paper studies the performance of different order Padé Fractional Order (FO) PD0.5 controllers applied to the leg joint control of a hexapod robot with two dof legs and joint actuators with saturation. For simulation purposes the robot prescribed motion is characterized through several locomotion variables and for the walking performance evaluation are used two indices, one based on the mean absolute density of energy per travelled distance and the other on the hip trajectory errors. A set of simulation experiments reveals the influence of the different order Padé PD0.5 controllers tuning upon the proposed indices. Copyright © 2006 IFAC.

Abstract
The accompanying of civil infrastructures behavior during their whole life cycle is growing within the last few years. This fact is due to several problems detected in such structures, which is the main reason for the dispended budget by owners in their maintenance, being even higher than other costs. In another way, traditional surveillance techniques, although important are expensive, slow in time and subjective. Considering such panorama, within a national research project - SMARTE project - a new technique for management and maintenance of structures was developed and implemented in a real structure, a pre-stressed concrete bridge (Sorraia River Bridge). The developed technique, long term structural health monitoring, has as a final purpose the execution of structural maintenance in an objective and efficient way. The evaluation of the structural behavior during whole life cycle is performed in an "on line" continuous way, allowing the on time detection of existent damages. Civil infrastructures health monitoring should have the potential for the on time detection of possible anomalies or critical situations, diminishing costs related to inspections and simultaneously growing structural and users' security. Inserted in a research project - SMARTE project - a new surveillance technique for the prevention and support of civil infrastructures maintenance and management was applied into a real prototype structure - Sorraia River Bridge (Perdigão et al. 2004). The developed long term structural health monitoring is composed by a sensory, a data acquisition, a communication, a data processing and archiving and damage detection and modelling system (Figueiras et al. 2004, Matos et al. 2005). Figure 1 presents a simple and illustrative scheme of it. SMARTE project has two main objectives. The first one is related to the installation of the sensory system in the bridge, during it execution phase, which should be liable and robust. In Fig. 2 it is possible to observe the used cantilever constructive process and utilized instrumentation devices (Figueiras et al. 2004). This respective component, based on sensors that were placed in special locations according to a previously established criteria, will allow the readings and storage of most important parameters for a correct interpretation of the structure behaviour during it whole life cycle. The second main objective is related to the development of a component for data processing and archiving. Such system should translate the obtained data in more objective information that could be used as decision criteria for civil infrastructures management. In this article it is presented the SMARTE project and respective main objectives. A brief description of each system of the developed and implemented long term structural health monitoring scheme is also executed. The initially proposed objectives were achieved and new research themes appeared with this project. A new project was so initialized which aim is to continue the Sorraia River Bridge long term monitoring and to develop the previous identified investigation subjects. (Figure Presented) © 2006 Taylor & Francis Group.

Abstract
We compare two link analysis ranking methods of web pages in a site. The first, called Site Rank, is an adaptation of PageRank to the granularity of a web site and the second, called Popularity Rank, is based on the frequencies of user clicks on the outlinks in a page that are captured by navigation sessions of users through the web site. We ran experiments on artificially created web sites of different sizes and on two real data sets, employing the relative entropy to compare the distributions of the two ranking methods. For the real data sets we also employ a nonparametric measure, called Spearman's footrule, which we use to compare the top-ten web pages ranked by the two methods. Our main result is that the distributions of the Popularity Rank and Site Rank are surprisingly close to each other, implying that the topology of a web site is very instrumental in guiding users through the site. Thus, in practice, the Site Rank provides a reasonable first order approximation of the aggregate behaviour of users within a web site given by the Popularity Rank.

Abstract
Test stimuli generation and power consumption are two Issues that jeopardize the design of built-in self test schemes. The LNA testing approach presented herein relies on converting the amplifier Into an oscillator and on using a low-power correlator to obtain a signature from the cross-correlation between the dynan-dc power supply current and the LNA's output voltage. In test mode a high fault coverage is obtained together with a low power consumption, while avoiding an extra stimulus generator. No significant performance degradation results from the added test circuitry. Concerning the Interface with the external tester, a digital signal is required to switch between normal and test modes, as well as a low frequency line to capture the correlator DC output voltage.

Abstract

Abstract
The objective of this work was to study, understand and evaluate the effect of different geometric configurations of carbon plies, in the reflected wavelength spectrum of Bragg grating structure together with the effect of the recoating process of the sensor. The different possibilities depend upon the orientation and location of the optical fibre relative to the composite reinforcement orientation and the presence/absence of recoating. The material stacking sequence and the cure conditions were are also studied and the influence of the different possibilities was considered. The optical spectrum response obtained by the interaction of the optical fibre with the host material is shown.