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Publicações

Publicações por PHT

2006

SMARTE - Development and implementation of a long term structural health monitoring

Autores
Perdigao, V; Barros, P; Matos, JC; Sousa, H; Figueiras, JA; Dias, I; Pereira, D;

Publicação
Proceedings of the 3rd International Conference on Bridge Maintenance, Safety and Management - Bridge Maintenance, Safety, Management, Life-Cycle Performance and Cost

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.

2006

The signal characteristics of the spectral response of Bragg grating sensor embedded in composite laminated after the cure process

Autores
Ramos, CA; Frazao, O; Dias, I; Marques, AT;

Publicação
ADVANCED MATERIALS FORUM III, PTS 1 AND 2

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.

2005

Advanced optical technologies for monitoring estuaries and coastal environments

Autores
Pereira, D; Frazao, O; Ferreira, J; Dias, I; Dias, JM; Teixeira, M; Vaz, N; Quintela, A; Lopes, JF; Santos, JL;

Publicação
CIENCIAS MARINAS

Abstract
In recent years the need to monitor different parameters has led to the development of several architectures able to make real time, un-attended measurements. Particularly in regard to environmental issues, it is very important that the equipment and measuring systems be small and light to avoid maximum interference of the ecosystems Studied. In this context, optical fibre sensors have become extremely attractive for use in natural environments to monitor different parameters of biological interest, due to their intrinsic small weight and size and low reactivity to chemical and biological parameters. In this paper we present an innovative and technologically advanced system for the simultaneous measurement of temperature and salinity based on optical fibre Bragg grating sensors and on an optical sensing cable especially designed for large-scale and distributed or quasi-distributed measurements. A prototype of this optical cable was installed in the Mira Channel at Ria de Aveiro, Portugal. Temperature variation during three weeks from 4 to 23 June 2002 is investigated and presented here.

2005

Monte Carlo simulation for the optical transmittance in biological tissues during the action of osmotic agents

Autores
Oliveira, L; Lage, A;

Publicação
Saratov Fall Meeting 2004: Optical Technologies in Biophysics and Medicine VI

Abstract
Computational methods have been used with great application to biomedical optics. The events created by the interaction of radiation with biological materials can easily be translated to computer languages with the objective of producing simulation techniques to be used prior to physical intervention. The addition of biocompatible and hyper osmotic agents to several types of biological tissues has proven the enhancement of transparency to radiation flux by reduction of material's optical properties. The evolutionary behavior of the agent's action in the tissue samples before saturation has been observed by numerous researchers but has never been described mathematically. In the present work we will describe the application of Monte Carlo simulation to estimate the evolutionary states of optical transparency of biological tissues when immersed in an osmotic solution. We begin our study with typical values for the optical properties of rabbit muscle and proceed by reducing the absorption and scattering coefficients independently and simultaneously. The results show the number of transmitted, absorbed, scattered and reflected photons in different stages of the action of a generic osmotic agent over a small and well defined tissue sample.

2004

Color and Turbidity evolution in the ageing process of Port Wine

Autores
Manuel, L; Oliveira, C;

Publicação
SARATOV FALL MEETING 2003: OPTICAL TECHNOLOGIES IN BIOPHYSICS AND MEDICINE V

Abstract
Port Wine ageing process is very important to produce the most appreciated and expensive wines from the class. The process takes decades to accomplish and involves particular techniques which are taken inside refrigerated cellars. Different wines pass through such process to produce 10 year, 20 year, 30 year and 40 year Ports. There are no documented data about color or turbidity evolution during the ageing process. We decided to verify the states of color and spectral turbidity of different aged Gold white port wine. The acquired results show a spectral evolution on transmition and scattered radiation along with color modification which are a close and direct consequence of adopted corrective measures. In measuring the four samples, we have used our spectronephelometer with optical fiber tips to illuminate sample and to acquire transmitted or scattered radiation. Transmition results were calibrated with a standard spectrophotometer at our laboratory, and scattered spectra were measured considering a system calibration with ISO12103 standard dust. We are aware that the four samples were harvested in different years, but the wine type is the same and the ageing process does not differ from one sample to another.

2003

Port wine spectronephelometry

Autores
Oliveira, LMC; Clemente, MACP;

Publicação
OPTICS AND LASER TECHNOLOGY

Abstract
The main purpose of this research was to create a portable equipment capable of measuring colour and turbidity during production of port wine. Actually, human, chemical and colour analysis are performed in key production stages for quality control. Several wine transformation processes are done without any kind of control. By using a fibre optic illuminator with a tungsten/halogen light source and a small spectrometer with fibre optic input, it was possible to perform angular measurements in wine samples. We have adapted these optical devices with a specially designed mechanical equipment which allows the passage of the wine during production. The spectral measurements were acquired in four different angular positions in a bypass of the mechanical support. This way we could determine colour coordinates and spectral transmittance and turbidity for three stages of a Ruby production. The entire equipment assembly had been previously calibrated in terms of colour and turbidity determination. The obtained results are in agreement with wine transformations between measurements, showing a small variation in colour and a high diminishing in spectral turbidity when filtration was performed. Transmittance has also increased after filtration turning the wine more limpid as it should be for human appreciation.

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