6,628 research outputs found

    Methodologies and Applications Review

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    Funding Information: The Authors acknowledge Fundação para a Ciência e a Tecnologia (FCT-MCTES) for its financial support via the project UIDB/00667/2020 (UNIDEMI). Pedro M. Ferreira also acknowledges FCT-MCTES for funding the PhD grant UI/BD/151055/2021. Publisher Copyright: © 2022 by the authors.Sensing Technology (ST) plays a key role in Structural Health-Monitoring (SHM) systems. ST focuses on developing sensors, sensory systems, or smart materials that monitor a wide variety of materials’ properties aiming to create smart structures and smart materials, using Embedded Sensors (ESs), and enabling continuous and permanent measurements of their structural integrity. The integration of ESs is limited to the processing technology used to embed the sensor due to its high-temperature sensitivity and the possibility of damage during its insertion into the structure. In addition, the technological process selection is dependent on the base material’s composition, which comprises either metallic or composite parts. The selection of smart sensors or the technology underlying them is fundamental to the monitoring mode. This paper presents a critical review of the fundaments and applications of sensing technologies for SHM systems employing ESs, focusing on their actual developments and innovation, as well as analysing the challenges that these technologies present, in order to build a path that allows for a connected world through distributed measurement systems.publishersversionpublishe

    Granting Sensorial Properties to Metal Parts through Friction Stir Processing

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    The authors would like also to thank to Micronsense-Metrologia Industrial (Leiria, Portugal) for the μCT analysis. The authors would also like to thank Prof. Catarina Santos for granting access to the MicroLab - Electron Microscopy Laboratory (Instituto Superior Técnico) for the SEM analyses.Structural Health Monitoring systems assess the part's current condition. This can be performed with a monitoring system comprising sensors, on the surface or embedded, in the monitored parts. However, surface sensors are subject to damage, and embedding the sensors may result in a weakened part. An innovative Self-Sensing Material and its manufacturing process were developed and are presented herein. As proof of concept, Barium Titanate particles were introduced and dispersed into an AA5083-H111 part by Friction Stir Processing (FSP). The particles’ distribution and concentration was evaluated by a set of characterization techniques, demonstrating that greater concentrations, grant enhanced sensitivity to the material. The use of FSP and the embedded particles improved the part’s mechanical behaviour in the processed zone. The sensorial properties were assessed and the response to a set of dynamic loads was measured, being coherent with the solicitations provided. The developed self-sensing material revealed an electrical sensitivity of 12.0 × 10-4 uV/MPa.publishersversionpublishe

    Hydro-wind optimal operation for joint bidding in day-ahead market: storage efficiency and impact of wind forecasting uncertainty

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    Wind power production is uncertain. The imbalance between committed and delivered energy in pool markets leads to the increase of system costs, which must be incurred by defaulting producers, thereby decreasing their revenues. To avoid this situation, wind producers can submit their bids together with hydro resources. Then the mismatches between the predicted and supplied wind power can be used by hydro producers, turbining or pumping such differences when convenient. This study formulates the problem of hydro-wind production optimization in operation contexts of pool market. The problem is solved for a simple three-reservoir cascade case to discuss optimization results. The results show a depreciation in optimal revenues from hydro power when wind forecasting is uncertain. The depreciation is caused by an asymmetry in optimal revenues from positive and negative wind power mismatches. The problem of neutralizing the effect of forecasting uncertainty is subsequently formulated and solved for the three-reservoir case. The results are discussed to conclude the impacts of uncertainty on joint bidding in pool market contexts.info:eu-repo/semantics/acceptedVersio

    Wearable biopotential measurement using the TI ADS1198 analog front-end and textile electrodes : signal conditioning and signal quality assessment

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    The development of mobile systems for monitoring bioelectric signals outside a hospital environment involves many challenges that do not arise when it is in a controlled environment, like a hospital. The dimensions of these systems are an important factor to consider in order to facilitate their use without interfering with the daily activities of individuals. The purpose of this work is the implementation of a single-supply battery-powered, low power ECG/EMG signal monitoring system based on the ADS1198 Analog Front-End from Texas Instruments. The system was designed to acquire ECG signals from three electrodes using the integrated Right-Leg-Drive (RLD) circuit from the ADS1198. The developed analog front-end was connected for testing purposes through the SPI interface to a NI-USB 8451 board and signals were acquired using LabVIEW. The circuit was tested in several situations and proved to provide high quality signals using textile integrated electrodes and conventional disposable gel electrodes.FEDER- “Programa Operacional Factores de Competitividade – COMPETE”, FCT - Fundação para a Ciência e a Tecnologia, projects PEst-C/CTM/UI0264/2011 and PTDC/EEA-ELC/70803/2006, and Instituto de Telecomunicaçõe

    Continuous health monitoring using e-textile integrated biosensors

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    In this work, continuous health monitoring for disabled or elderly people is proposed using textile integrated electrodes for ECG measurement. Other applications, such as EMG or skin impedance measurement are also envisaged. The paper specifically describes a shirt integrating electrodes for ECG measurement that has been tested in several conditions. The techniques for integration of ECG electrodes can be directly applied for production of EMG or skin-impedance electrodes.Signal processing techniques for heart rate value extraction and to deal with low-quality signal or motion artefacts are being tested and will also be described. Results show that signals acquired with the shirt are comparable to signals acquired with conventional gel electrodes. The complete integration of the electrodes into clothing may have a very interesting psychological benefit, but some issues related to comfort and daily use have to be further investigated.Fundação para a Ciência e a Tecnologia (FCT

    Dinâmica da matéria orgânica sob sistemas de manejo no solo no município de Paragominas-PA.

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    Uma das características marcantes do plantio direto é o aumento do teor de matéria orgânica na camada superficial do solo com o decorrer do tempo de sua implantação. O presente trabalho teve como objetivo avaliar a dinâmica da matéria orgânica sob sistemas de manejo em Paragominas-PA. O estudo foi executado na fazenda Juparanã, com delineamento de blocos ao acaso com quatro tratamentos, o T1 (plantio direto: soja/milho em rotação), T2 (plantio direto: milho/soja, em rotação), T3 (plantio convencional: soja/milho) e T4 (plantio convencional: monocultivo de soja) com três repetições. Foram coletadas amostras deformadas, na camadas: 0-5, 5-10, 10-20, 20-30 e 30-50 cm. A MO, foi analisada no Laboratório de Solos da Embrapa Amazônia Oriental e as médias foram submetidas à análise de variância. Conclui-se que o plantio direto proporcionou ao longo do tempo aumento nos teores de matéria orgânica no solo, quando comparado ao de preparo convencional

    Embryonal rhabdomyosarcoma of the uterine cervix: a rare case report

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    Embryonal rhabdomyosarcoma of the female genital tract is a rare tumour. It tends to occur during childhood in the vagina and, rarely, it can arise in the uterine cervix, with a peak incidence in the second decade. We report a case of a 18-year-old female with an embryonal rhabdomyosarcoma (sarcoma botryoides) presenting himself as a cervical polyp. This tumour consisted of rhabdomyoblasts with miscellaneous differentiation surrounded by a loose, myxoid stroma. The patient was successfully treated with cervical conization and adjuvant chemotherapy. She is now disease-free at the 28th month follow-up. Awareness of this uncommon lesion in the cervix and its clinical implications is important to prevent misdiagnosis. Therapy has recently inclined to conservative and fertility-sparing treatment

    Production of electroactive filaments by coextrusion

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    The development of new products for i-textiles (interactive textiles) or e-textiles (electronic textiles) applications shows a significant growth in the most recent years due to their huge potential. Although much scientific work has been published in the last years, actual practical applications are still limited. This is due, on one hand, to unsatisfactory state of development of the technology and, on the other, to difficulties on the integration of technologies and methods of the textile and electronic areas. Products for e/i-textiles very often involve the use of sensors, preferably in the form of films, filaments or fibres, due to the inherent easy insertion in the product. For this purpose, electroactive filaments, that benefit from the piezoelectric properties of poly(vinylidene fluoride), PVDF, can be an interesting choice. There aresome works published in the literature related to the development of films with piezoelectric properties [1], that employ PVDF as the electroactive material. However, despite its importance, the manufacture methodologies employed are very difficult to use in industrial scale production. In this work a novel methodology for the production of electroactive filaments, by coextrusion of PVDF and an electrical conductive polymer composite, is proposed and tested. The developed methodology involves a conventional coextrusion line, and can be easily scaled up for industrial massive production. It is shown that The PVDF filament with a conductive PP/carbon black composite core crystallizes in the crystalline phase related just to the temperatures and stretch ratio conditions, independently of the existence of the conductive core: for 80ºC the material crystallizes in the -phase and undergoes increasing to phase transformation for increasing stretch ratios from 1 to 5.FCT- Portuguese Foundation for Science and Technology through the projects PTDC/CTM/69316/2006, NANO/NMed-SD/0156/2007 and PTDC/CTM/108801/2008 and FEDER via FCT, Fundação para a Ciência e Tecnologia, under the POCI 2010 and Pluriannual programs. A.F., P.C. and V. S. thank the FCT grants SFRH/BD/69796/2010, SFRH/BD/64267/2009 and SFRH/BPD/63148/200

    Laser Doppler Measurements of Twin Impinging Jets Aligned with a Crossflow

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    This paper presents a detailed analysis of the complex flow beneath two impinging jets aligned with a low-velocity crossflow which is relevant for the future F-35 VSTOL configuration, and provides a quantitative picture of the main features of interest for impingement type of flows. The experiments were carried out for a Reynolds number based on the jet exit conditions of Rej = 4.3 104, an impingement height of 20.1 jet diameters and for a velocity ratio between the jet exit and the crossflow VR = Vj/Uo of 22.5. The rear jet is located at S = 6 D downstream of the first jet. The results show a large penetration of the first (upstream) jet that is deflected by the crossflow and impinges on the ground, giving rise to a ground vortex due to the collision of the radial wall and the crossflow that wraps around the impinging point like a scarf. The rear jet (located downstream) it is not so affected by the crossflow in terms of deflection, but due to the downstream wall jet that flows radially from the impinging point of the first jet it does not reach the ground. The results indicate a new flow pattern not yet reported so far, that for a VSTOL aircraft operating in ground vicinity with front wind or small forward movement may result in enhanced under pressures in the aft part of the aircraft causing a suction down force and a change of the pitching moment towards the ground.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
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