2016
Authors
Coelho, L; Viegas, D; Santos, JL; de Almeida, JMMM;
Publication
TALANTA
Abstract
A hybrid optical sensing scheme based on a fiber Bragg grating (FBG) combined with a titanium dioxide coated long period fiber grating (LPFG) for monitoring organic solvents in high refractive index edible oils is reported. In order to investigate and optimize the sensor performance, two different FBG/LPFG interrogation systems were investigated. The readout of the sensor was implemented using either the wavelength shift of the LPFG resonance dip or the variation in the optical power level of the reflected/transmitted light at the FBG wavelength peak, which in turn depends on the wavelength position of the LPFG resonance. Hexane concentrations up to 20%V/V, corresponding to the refractive index range from 1.451 to 1.467, were considered. For the transmission mode of operation, sensitivities of 1.41 nm/%V/V and 0.11 dB/%V/V, with resolutions of 0.58%V/V and 0.29%V/V, were achieved when using the LPFG wavelength shift and the FBG transmitted optical power, respectively. For the FBG reflection mode of operation, a sensitivity of 0.07 dB/V/V and a resolution better than 0.16%V/V were estimated.
2016
Authors
Moayyed, H; Leite, IT; Coelho, L; Santos, JL; Viegas, D;
Publication
PHOTONIC SENSORS
Abstract
Optical fiber optrodes are attractive sensing devices due to their ability to perform point measurement in remote locations. Mostly, they are oriented to biochemical sensing, quite often supported by fluorescent and spectroscopic techniques, but with the refractometric approach considered as well when the objective is of high measurement performance, particularly when the focus is on enhancing the measurand resolution. In this work, we address this subject, proposing and analyzing the characteristics of a fiber optic optrode relying on plasmonic interaction. A linearly tapered optical fiber tip is covered by a double overlay: the inner one - a silver thin film and over it a dielectric layer, with this combination allowing to achieve, at a specific wavelength range, surface plasmonic resonance (SPR) interaction sensitive to the refractive index of the surrounding medium. Typically, the interrogation of the SPR sensing structures is performed, considering spectroscopic techniques, but in principle, a far better performance can be obtained, considering the reading of the phase of the light at a specific wavelength located within the spectral plasmonic resonance. This is the approach which is studied here in the context of the proposed optical fiber optrode configuration. The analysis performed shows the combination of a silver inner layer with a dielectric titanium oxide layer with tuned thicknesses enables sensitive phase reading and allows the operation of the fiber optic optrode sensor in the third telecommunication wavelength window.
2016
Authors
Coelho, L; Viegas, D; Santos, JL; de Almeida, JMMM;
Publication
OPTICAL SENSING AND DETECTION IV
Abstract
The detection of volatile organic compounds is accomplished with a sensing device based on a long period fiber grating (LPFG) coated with a zinc oxide (ZnO) thin layer with self-temperature compensation. The ZnO coating structure was produced onto the cladding of the fiber by thermal oxidation of a metallic Zn thin film. The morphological characterization of ZnO thin films, grown at the same time on silicon substrates, was performed using X-ray diffraction, X-ray Photoelectron Spectroscopy and Scanning Electron Microscope which shows very good agreement. LPFGs with 290 nm thick ZnO coating were fabricated and characterized for the detection of ethanol and hexane in vapor phase. For ethanol a sensitivity of 0.99 nm / g.m(-3) was achieved when using the wavelength shift interrogation mode, while for hexane a much lower sensitivity of 0.003 nm / g.m(-3) was measured, indicating a semi-selectivity of the sensor with a spectral resolution better than 3.2 g.m(-3).
2016
Authors
Pires, A; Chamine, HI; Piqueiro, F; Perez Alberti, A; Rocha, F;
Publication
ENVIRONMENTAL EARTH SCIENCES
Abstract
Digital photogrammetry and GIS-based mapping are increasingly recognised as powerful tools in littoral issues. This paper considers the interoperability framework for high-resolution imagery acquisition and the development of coastal geoscience maps. The layered system architecture of the cartographic methodology is also explained. Moreover, it highlights a new approach to assessing heterogeneous geologic, geomorphological and maritime environments. The main goal of the present study was to test a new concept for photogrammetric images in order to assist modelling techniques, spatial analysis and coastal conceptual models. This approach proposes a methodological approach to coastal zone monitoring and to maritime forcing conditions evaluating. This approach will allow: (1) the acquisition of a large archive of high-resolution imagery; (2) the development of a coastal database including the entire data field and in situ assessments; (3) the study of coastal dynamics and shoreline evolution; (4) the assessment of the rock platforms and hydraulic structures; (5) the production of coastal geosciences maps. An integrated coastal geoscience and engineering methodology was outlined in NW of Iberian Peninsula (South Galicia and North/Central Portugal regions). This paper reports on the increased knowledge of the studied regions, providing essential data concerning coastal geo-morphodynamics. The overall assessment revealed additional evidence of erosion issues, which contributes to a better understanding of the hydraulic conditions. The main results are presented in regional coastal geoscience maps and local approach-outputs that could help government, local authorities and stakeholders to develop coastal management plans and to recommend strategies.
2016
Authors
Pires, A; Chamine, HI; Nunes, JC; Borges, PA; Garcia, A; Sarmento, E; Antunes, M; Salvado, F; Rocha, F;
Publication
VOLCANIC ROCKS AND SOILS
Abstract
This work describes a preliminary methodological framework for the assessment of coastal volcanic rocky platforms in Pico Island (Azores). This study also deals with the importance of GIS-based mapping and unmanned aerial vehicles (UAVs) whichwere tested in two studied areas (Lajes and Madalena sites). This research gives an overview about the UAVs work flow and its application for photogrammetric assessment of coastal volcanic rocky platforms. The main purpose of this study is to explore the influence of basaltic lava coastal platforms and associated boulder strewn, which are well differentiated in Lajes and Madalena sites. In general, this research describes the image acquisition process and the UAV LiDAR technology and the aerial surveys to acquire the geodatabase which will enable the design of geoscience and geotechnical maps on coastal volcanic rock platforms. The images analysis will allow: (i) boulder geotechnical description and evaluation; (ii) shore and coastal platform assessment; (iii) propose monitoring coastal plans (short to long-term); (iv) rock boulders (basaltic blocks) mobility, movement trend, imbrication, indicating flow and source direction; (v) obtain DTM and contour lines to generate 3D models of the coastal area. All these data is crucial to understand the coastal dynamics of the sites and develop an applied mapping which couples GIS technologies and UAV based spatial platform. It was also developed a GNSS (Global Navigation Satellite System) datasheet which incorporates the entire database of ground control points, using high resolution GPS system for the georeferencing and differential correction process. This research presents the preliminary results of the coastal geotechnics mapping for volcanic environments. Furthermore, high resolution image acquisition, georeferencing and differential correction of the ground control points using high accuracy GPS, were also thorough analysed to improve the general methodology presented herein. Finally, it was proposed a preliminary integrated coastal engineering study for the rocky platform zoning and short to long-term monitoring in selected sites on Pico Island. The study was partially financed by FEDEREU COMPETE Funds and FCT (GeoBioTec|UA: UID/GEO/04035/2013) and LABCARGA|ISEP reequipment program: IPP-ISEP|PAD’2007/08. © 2016 Taylor & Francis Group, London.
2016
Authors
Costa, PJ; Moreira, N; Campos, D; Goncalves, J; Lima, J; Costa, PL;
Publication
IEEE REVISTA IBEROAMERICANA DE TECNOLOGIAS DEL APRENDIZAJE-IEEE RITA
Abstract
The Robot@Factory competition was recently included in Robotica, the main Portuguese Robotics Competition. This robot competition takes place in an emulated factory plant, where automatic guided vehicles (AGVs) must cooperate to perform tasks. To accomplish their goals, the AGVs must deal with localization, navigation, scheduling, and cooperation problems that must be solved autonomously. This robot competition can play an important role in education due to its inherent multidisciplinary approach, which can motivate students to bridge different technological areas. It can also play an important role in research and development, because it is expected that its outcomes will later be transferred to real-world problems in manufacturing or service robots. By presenting a scaled-down factory shop floor, this competition creates a benchmark that can be used to compare different approaches to the challenges that arise in this kind of environment. The ability to alter the environment, in some restricted areas, can usually promote the test and evaluation of different localization mechanisms, which is not possible in other competitions. This paper presents one of the possible approaches to build a robot capable of entering this competition. It can be used as a reference to current and new teams.
The access to the final selection minute is only available to applicants.
Please check the confirmation e-mail of your application to obtain the access code.