2022
Authors
Rodrigues, AV; Monteiro, C; Silva, SO; Linhares, C; Mendes, H; Tavares, SMO; Frazão, O;
Publication
U.Porto Journal of Engineering
Abstract
In this work, a brief review on the application of fiber optic sensors on power grid apparatus is presented. Power transformers, which are the nodes between electrical transmission lines, are the most expensive, critical and one of the central units of this network. The failure of electrical machines compromises the whole grid leading to power outages and income losses. Thus, constant monitoring of structural health and operating conditions of core infrastructures is sought. With different types of sensors either on the market or in the literature, it is possible to measure physical parameters that make this equipment more reliable. © 2022, Universidade do Porto - Faculdade de Engenharia. All rights reserved.
2022
Authors
Miguel N. Marques; Cristiano O. Pontelli; Ely C. de Paiva;
Publication
Procedings do XXIV Congresso Brasileiro de Automática - Procedings do XXII Congresso Brasileiro de Automática
Abstract
2022
Authors
Ferreira, MFS; Silva, NA; Guimarães, D; Martins, RC; Jorge, PAS;
Publication
U.Porto Journal of Engineering
Abstract
Laser-induced breakdown spectroscopy (LIBS) is a technique that leverages atomic emission towards element identification and quantification. While the potential of the technology is vast, it still struggles with obstacles such as the variability of the technique. In recent years, several methods have exploited modifications to the standard implementation to work around this problem, mostly focused on the laser side to increase the signal-to-noise ratio of the emission. In this paper, we explore the effect of pulse duration on the detected signal intensity using a tunable LIBS system that consists of a versatile fiber laser, capable of emitting square-shaped pulses with a duration ranging from 10 to 100 ns. Our results show that, by tuning the duration of the pulse, it is possible to increase the signal-to-noise ratio of relevant elemental emission lines, an effect that we relate with the computed plasma temperature and associated density for the ion species. Despite the limitations of the work due to the low-resolution and small range of the spectrometer used, the preliminary results pave an interesting path towards the design of controllable LIBS systems that can be tailored to increase the signal-to-noise ratio and thus be useful for the deployment of more sensitive instruments both for qualitative and quantitative purposes. © 2022, Universidade do Porto - Faculdade de Engenharia. All rights reserved.
2022
Authors
Barros, BJ; Cunha, JPS;
Publication
2022 IEEE 21ST MEDITERRANEAN ELECTROTECHNICAL CONFERENCE (IEEE MELECON 2022)
Abstract
Optical Fiber Tweezers (OFT) can be used to study manifestations of light-matter interactions and deduce properties of micron-sized bioparticles trapped within its laser focal point. Our group has previously co-invented an innovative approach for this purpose based on advanced optical signal processing named iLoF-intelligent Lab on Fiber- with very relevant results revealing it is possible to create a variety of time and frequency magnitude features for label-free and non-invasive optical fiber sensing technologies. Nevertheless, phase spectra has been neglected in these photonics approaches. In this context, we present an exploratory study on informative content extraction from phase of OFT back-scattering signals. Furthermore, we analyze if these phase features provide better discriminative performance when compared spectrum magnitude ones previously used by the iLoF technology. The phase spectrum of back-scattering signals showed to retain patterns related to the intrinsic properties of each particle and the derived set of features proved to be robust to detect and discriminate from synthetic microparticles to highly similar cancer-derived mammalian cells, with better discriminative potential than their previous magnitude spectral counterparts. Such results introduce phase as a potential new domain to obtain discriminative light pattern features from OFT systems applied to micron-sized particles detection. The high sensitivity of the analyzed phase features to different micron-sized bioparticles, namely cancer-associated glycoforms, presents great potential for future applications in point-of-care diagnosis, such as detection and identification of molecules circulating in the blood or its derivatives with important clinical outcomes.
2022
Authors
Forcen Munoz, M; Pavon Pulido, N; Lopez Riquelme, JA; Temnani Rajjaf, A; Berrios, P; Morais, R; Perez Pastor, A;
Publication
SENSORS
Abstract
Crop sustainability is essential for balancing economic development and environmental care, mainly in strong and very competitive regions in the agri-food sector, such as the Region of Murcia in Spain, considered to be the orchard of Europe, despite being a semi-arid area with an important scarcity of fresh water. In this region, farmers apply efficient techniques to minimize supplies and maximize quality and productivity; however, the effects of climate change and the degradation of significant natural environments, such as, the "Mar Menor", the most extent saltwater lagoon of Europe, threatened by resources overexploitation, lead to the search of even better irrigation management techniques to avoid certain effects which could damage the quaternary aquifer connected to such lagoon. This paper describes the Irriman Platform, a system based on Cloud Computing techniques, which includes low-cost wireless data loggers, capable of acquiring data from a wide range of agronomic sensors, and a novel software architecture for safely storing and processing such information, making crop monitoring and irrigation management easier. The proposed platform helps agronomists to optimize irrigation procedures through a usable web-based tool which allows them to elaborate irrigation plans and to evaluate their effectiveness over crops. The system has been deployed in a large number of representative crops, located along near 50,000 ha of the surface, during several phenological cycles. Results demonstrate that the system enables crop monitoring and irrigation optimization, and makes interaction between farmers and agronomists easier.
2022
Authors
Penas, S; Araujo, T; Mendonca, AM; Faria, S; Silva, J; Campilho, A; Martins, ML; Sousa, V; Rocha Sousa, A; Carneiro, A; Falcao Reis, F;
Publication
GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY
Abstract
Purpose This study aims to investigate retinal and choroidal vascular reactivity to carbogen in central serous chorioretinopathy (CSC) patients. Methods An experimental pilot study including 68 eyes from 20 CSC patients and 14 age and sex-matched controls was performed. The participants inhaled carbogen (5% CO2 + 95% O-2) for 2 min through a high-concentration disposable mask. A 30 degrees disc-centered fundus imaging using infra-red (IR) and macular spectral domain optical coherence tomography (SD-OCT) using the enhanced depth imaging (EDI) technique was performed, both at baseline and after a 2-min gas exposure. A parametric model fitting-based approach for automatic retinal blood vessel caliber estimation was used to assess the mean variation in both arterial and venous vasculature. Choroidal thickness was measured in two different ways: the subfoveal choroidal thickness (SFCT) was calculated using a manual caliper and the mean central choroidal thickness (MCCT) was assessed using an automatic software. Results No significant differences were detected in baseline hemodynamic parameters between both groups. A significant positive correlation was found between the participants' age and arterial diameter variation (p < 0.001, r= 0.447), meaning that younger participants presented a more vasoconstrictive response (negative variation) than older ones. No significant differences were detected in the vasoreactive response between CSC and controls for both arterial and venous vessels (p = 0.63 and p = 0.85, respectively). Although the vascular reactivity was not related to the activity of CSC, it was related to the time of disease, for both the arterial (p = 0.02, r = 0.381) and venous (p = 0.001, r= 0.530) beds. SFCT and MCCT were highly correlated (r= 0.830, p < 0.001). Both SFCT and MCCT significantly increased in CSC patients (p < 0.001 and p < 0.001) but not in controls (p = 0.059 and 0.247). A significant negative correlation between CSC patients' age and MCCT variation (r = - 0.340, p = 0.049) was detected. In CSC patients, the choroidal thickness variation was not related to the activity state, time of disease, or previous photodynamic treatment. Conclusion Vasoreactivity to carbogen was similar in the retinal vessels but significantly higher in the choroidal vessels of CSC patients when compared to controls, strengthening the hypothesis of a choroidal regulation dysfunction in this pathology.
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