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Detalhes

Detalhes

019
Publicações

2021

Hyperspectral Imaging System for Marine Litter Detection

Autores
Freitas S.; Silva H.; Almeida C.; Viegas D.; Amaral A.; Santos T.; Dias A.; Jorge P.A.S.; Pham C.K.; Moutinho J.; Silva E.;

Publicação
Oceans Conference Record (IEEE)

Abstract

2020

A robotic solution for NETTAG lost fishing net problem

Autores
Martins, A; Almeida, C; Lima, P; Viegas, D; Silva, J; Almeida, JM; Almeida, C; Ramos, S; Silva, E;

Publicação
GLOBAL OCEANS 2020: SINGAPORE - U.S. GULF COAST

Abstract
This paper presents an autonomous robotic system, IRIS, designed for lost fishing gear recovery. The vehicle was developed in the context of the NetTag project. This is a European Union project funded by EASME the Executive Agency for Small and Medium Enterprises addressing marine litter, and the reduction of quantity and impact of lost fishing gears in the ocean. NetTag intends to produce new technological devices for location and recovery of fishing gear and educational material about marine litter, raise awareness of fisheries industry and other stakeholders about the urgent need to combat marine litter and increase scientific knowledge on marine litter problematic, guaranteeing the engagement of fishers to adopt better practices to reduce and prevent marine litter derived from fisheries. The design of IRIS is presented in detail, addressing the mechanical design, hardware architecture, sensor system and navigation and control. Preliminary tests in tank and in controlled sea conditions are presented and ongoing developments on the recovery system are discussed. © 2020 IEEE.

2017

Monitoring of oxidation phases of copper thin films using long period fiber gratings

Autores
Coelho, L; Agostinho Moreira, JA; Tavares, PB; Santos, JL; Viegas, D; de Almeida, JMMM;

Publicação
SENSORS AND ACTUATORS A-PHYSICAL

Abstract
Long period fiber gratings (LPFGs) were used to monitor the characteristics of copper (Cu) thin films when annealed in air atmosphere up to similar to 680 degrees C. The wavelength and the optical power shift of the resonant bands of the LPFGs when coated with the Cu thin films, were measured as a function of the annealing temperature, and were found to exhibit a different evolution comparing to a bare LPFGs. Thin films of Cu deposited on quartz (SiO2) substrates were annealed and analyzed by XRD, SEM/EDS and Raman spectroscopy, allowing to identify the formation of two distinct oxide phases at different temperatures, cuprous (Cu2O-cuprite) and cupric (CuO-tenorite) oxides, respectively. The observed features of the resonant bands of the LPFGs were found to be associated with the Cu oxide phase transitions, indicating the possibility of using LPFGs to monitor, in real time, the oxidation states of Cu thin films by following specific characteristics of the attenuation bands. In addition, LPFGs over coated with the two distinct oxidation phases of Cu were characterized for refractive index sensing in the range between 1.300 to 1.600, leading to the conclusion that the sensitivity to the refractive index of the surrounding medium of Cu coated LPFGs sensing systems can be temperature tuned.

2017

Phase-interrogated SPR sensing structures based on tapered and tip optrode optical fiber configurations with bimetallic layers

Autores
Moayyed, H; Leite, IT; Coelho, L; Santos, JL; Viegas, D;

Publicação
MEASUREMENT SCIENCE AND TECHNOLOGY

Abstract
This work reports the theoretical investigation of optical fiber surface plasmon resonance sensors incorporating bimetallic layer combinations. Different metals like silver, gold, copper, and aluminum are considered to investigate the refractometric sensing properties of tapered and tip optrode phase-interrogated optical fiber plasmonic sensor structures. It is shown that the gold-silver combination, coupled to a tip optrode layout, is capable of maximizing the resolution and operation range of these sensing structures for environmental refractive index measurement.

2017

Adapting bobbert-vlieger model to spectroscopic ellipsometry of gold nanoparticles with bio-organic shells

Autores
Viegas, D; Fernandes, E; Queirós, R; Petrovykh, DY; De Beule, P;

Publicação
Biomedical Optics Express

Abstract
We investigate spectroscopic imaging ellipsometry for monitoring biomolecules at surfaces of nanoparticles. For the modeling of polarimetric light scattering off surface-adsorbed core-shell nanoparticles, we employ an extension of the exact solution for the scattering by particles near a substrate presented by Bobbert and Vlieger, which offers insight beyond that of the Maxwell-Garnett effective medium approximation. Varying thickness and refractive index of a model bio-organic shell results in systematic and characteristic changes in spectroscopic parameters ? and ?. The salient features and trends in modeled spectra are in qualitative agreement with experimental data for antibody immobilization and fibronectin biorecognition at surfaces of gold nanoparticles on a silicon substrate, but achieving a full quantitative agreement will require including additional effects, such as nanoparticle-substrate interactions, into the model. © 2017 Optical Society of America.