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Publicações

Publicações por João Ferreira

2014

An Adjustable Sensor Platform Using Dual Wavelength Measurements For Optical Colorimetric Sensitive Films

Autores
Machado, C; Gouveia, C; Ferreira, J; Kovacs, B; Jorge, P; Lopes, L;

Publicação
2014 IEEE SENSORS

Abstract
We present a new and versatile sensor platform to readout the response of sensitive colorimetric films. The platform is fully self-contained and based on a switched dual-wavelength scheme. After filtering and signal processing, the system is able to provide self-referenced measures of color intensity changes in the film, while being immune to noise sources such as ambient light and fluctuations in the power source and in the optical path. By controlling the power and the switching frequency between the two wavelengths it is possible to fine tune the output gain as well as the operational range of the sensor for a particular application, thus improving the signal conditioning. The platform uses a micro-controller that complements the analog circuit used to acquire the signal. The latter pre-amplifies, filters and conditions the signal, leaving the micro-controller free to perform sensor linearization and unit conversion. By changing the sensitive film and the wavelength of the light source it is possible to use this platform for a wide range of sensing applications.

2015

Monitoring of Coal Waste Piles With Fiber Optic Sensing Technology

Autores
Viveiros, D; Ribeiro, J; Ferreira, J; Pinto, AMR; Perez Herrera, RA; Diaz, S; Lopez Gil, A; Dominguez Lopez, A; Esteban, O; Martins, HF; Martin Lopez, S; Baierl, H; Auguste, JL; Jamier, R; Rougier, S; Santos, JL; Flores, D; Roy, P; Gonzalez Herraez, M; Lopez Amo, M; Baptista, JM;

Publicação
PROCEEDINGS OF 2015 3RD EXPERIMENT AT INTERNATIONAL CONFERENCE (EXP AT'15)

Abstract
Coal has been for centuries a central energy source to fulfill industrial and domestic needs. Its large scale extraction produced huge amount of debris that were piled in the neighboring of the mines, quite often going into combustion triggered by events like forest fires or lightning. When in this state it can continue for years, releasing substantial emissions of toxic and greenhouse gases with recognized impact in the environment and, more serious in the short term, in the life quality of the populations located nearby. Continuous monitoring of combustion temperature and emission levels of certain gases opens the possibility to plan corrective actions to minimize their negative impact. Optical fiber technology is wellsuited to this purpose and here it is described the main attributes of a fiber optic sensing system projected to gather data on distributed temperature and gas emission in these harsh environments.

2014

Fiber Optic Sensing System for Monitoring of Coal Waste Piles in Combustion

Autores
Viveiros, D; Ribeiro, J; Carvalho, JP; Ferreira, J; Pinto, AMR; Perez Herrera, RA; Diaz, S; Lopez Gil, A; Dominguez Lopez, A; Esteban, O; Martins, HF; Martin Lopez, S; Baierl, H; Auguste, JL; Jamier, R; Rougier, S; Santos, JL; Flores, D; Roy, P; Gonzalez Herraez, M; Lopez Amo, M; Baptista, JM;

Publicação
23RD INTERNATIONAL CONFERENCE ON OPTICAL FIBRE SENSORS

Abstract
The combustion of coal wastes resulting from mining is of particular environmental concern and therefore the importance of the proper management involving real-time assessment of their status and identification of probable evolution scenarios is recognized. Continuous monitoring of combustion temperature and emission levels of certain gases opens the possibility to plan corrective actions to minimize their negative impact in the surroundings. Optical fiber technology is well-suited to this purpose and in this work it is described the main attributes of a fiber optic sensing system projected to gather data on distributed temperature and gas emission in these harsh environments.

2017

ECOAL Project-Delivering Solutions for Integrated Monitoring of Coal-Related Fires Supported on Optical Fiber Sensing Technology

Autores
Ribeiro, J; Viveiros, D; Ferreira, J; Lopez Gil, A; Dominguez Lopez, A; Martins, HF; Perez Herrera, R; Lopez Aldaba, A; Duarte, L; Pinto, A; Martin Lopez, S; Baierl, H; Jamier, R; Rougier, S; Auguste, JL; Teodoro, AC; Goncalves, JA; Esteban, O; Santos, JL; Roy, P; Lopez Amo, M; Gonzalez Herraez, M; Baptista, JM; Flores, D;

Publicação
APPLIED SCIENCES-BASEL

Abstract
The combustion of coal wastes resulting from mining is of particular environmental concern, and the importance of proper management involving real-time assessment of their status and identification of probable evolution scenarios is recognized. Continuous monitoring of the combustion temperature and emission levels of certain gases allows for the possibility of planning corrective actions to minimize their negative impact on the surroundings. Optical fiber technology is well suited to this purpose and here we describe the main attributes and results obtained from a fiber optic sensing system projected to gather data on distributed temperature and gas emissions in these harsh environments.

2008

Frequency modulated continuous wave technique for referencing and multiplexing intensity based fibre optic sensors - art. no. 70044P

Autores
Perez Herrera, RA; Pereira, DA; Frazao, O; Ferreira, JMC; Santos, JL; Araujo, FM; Ferreira, LA; Baptista, JM; Lopez Amo, M;

Publicação
19TH INTERNATIONAL CONFERENCE ON OPTICAL FIBRE SENSORS, PTS 1 AND 2

Abstract
We report on the use of a frequency-reflectometry domain technique for referencing optical intensity sensors located between two fibre Bragg gratings. The experiment combines the concept of frequency modulated continuous wave with the spectrally selective mirror proper-ties of fibre Bragg gratings to interrogate with referencing properties intensity based sensors. Multiplexing two of these sensors using this technique in a parallel topology system was also experimentally demonstrated. Due to the use of different fibre lengths (delay lines), signals from the fibre Bragg gratings located at different positions in an array are separated in the frequency-domain.

2011

Optimization of the frequency-modulated continuous wave technique for referencing and multiplexing intensity-based fiber optic sensors

Autores
Perez Herrera, RA; Pereira, DA; Frazao, O; Ferreira, JMC; Santos, JL; Araujo, FM; Ferreira, LA; Baptista, JM; Lopez Amo, M;

Publicação
MEASUREMENT

Abstract
In this paper, we demonstrate the interrogation of fiber optic intensity sensors by using the combination of the frequency-modulated continuous wave concept with the spectral selective reflectivity of fiber Bragg gratings. Thus, we multiplex these kinds of sensors with this technique having simultaneously a referenced system. The basis of this dual functionality is described and results are presented for the case of interrogation of two multiplexed intensity sensors. Their evaluation permits to establish the conditions to address a sensor network of this type. Also, it is proposed a strategy to implement this sensing approach without the requirement of using optical fiber delay lines in the sensor heads.

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