66 research outputs found

    Sensores de fibra ótica para arquiteturas e-Health

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    In this work, optical fiber sensors were developed and optimized for biomedical applications in wearable and non-intrusive and/or invisible solutions. As it was intended that the developed devices would not interfere with the user's movements and their daily life, the fibre optic sensors presented several advantages when compared to conventional electronic sensors, among others, the following stand out: size and reduced weight, biocompatibility, safety, immunity to electromagnetic interference and high sensitivity. In a first step, wearable devices with fibre optic sensors based in Fiber Bragg gratings (FBG) were developed to be incorporated into insoles to monitor different walking parameters based on the analysis of the pressure exerted on several areas of the insole. Still within this theme, other sensors were developed using the same sensing technology, but capable of monitoring pressure and shear forces simultaneously. This work was pioneering and allowed monitoring one of the main causes of foot ulceration in people with diabetes: shear. At a later stage, the study focused on the issue related with the appearance of ulcers in people with reduced mobility and wheelchair users. In order to contribute to the mitigation of this scourge, a system was developed composed of a network of fibre optic sensors capable of monitoring the pressure at various points of the wheelchair. It not only measures the pressure at each point, but also monitors the posture of the wheelchair user and advises him/her to change posture regularly to reduce the probability of this pathology occurring. Still within this application, another work was developed where the sensor not only monitored the pressure but also the temperature in each of the analysis points, thus indirectly measuring shear. In another phase, plastic fibre optic sensors were studied and developed to monitor the body posture of an office chair user. Simultaneously, software was developed capable of monitoring and showing the user all the acquired data in real time and warning for incorrect postures, as well as advising for work breaks. In a fourth phase, the study focused on the development of highly sensitive sensors embedded in materials printed by a 3D printer. The sensor was composed of an optical fibre with a FBG and the sensor body of a flexible polymeric material called "Flexible". This material was printed on a 3D printer and during its printing the optical fibre was incorporated. The sensor proved to be highly sensitive and was able to monitor respiratory and cardiac rate, both in wearable solutions (chest and wrist) and in "invisible" solutions (office chair).Neste trabalho foram desenvolvidos e otimizados sensores em fibra ótica para aplicações biomédicas em soluções vestíveis e não intrusivas/ou invisíveis. Tendo em conta que se pretende que os dispositivos desenvolvidos não interfiram com os movimentos e o dia-a-dia do utilizador, os sensores de fibra ótica apresentam inúmeras vantagens quando comparados com os sensores eletrónicos convencionais, de entre várias, destacam-se: tamanho e peso reduzido, biocompatibilidade, segurança, imunidade a interferências eletromagnéticas e elevada sensibilidade. Numa primeira etapa, foram desenvolvidos dispositivos vestíveis com sensores de fibra ótica baseados em redes de Bragg (FBG) para incorporar em palmilhas de modo a monitorizar diferentes parâmetros da marcha com base na análise da pressão exercida em várias zonas da palmilha. Ainda no âmbito deste tema, adicionalmente, foram desenvolvidos sensores utilizando a mesma tecnologia de sensoriamento, mas capazes de monitorizar simultaneamente pressão e forças de cisalhamento. Este trabalho foi pioneiro e permitiu monitorizar um dos principais responsáveis pela ulceração dos pés em pessoas com diabetes: o cisalhamento. Numa fase posterior, o estudo centrou-se na temática relacionada com o aparecimento de úlceras em pessoas com mobilidade reduzida e utilizadores de cadeiras de rodas. De modo a contribuir para a mitigação deste flagelo, procurou-se desenvolver um sistema composto por uma rede de sensores de fibra ótica capaz de monitorizar a pressão em vários pontos de uma cadeira de rodas e não só aferir a pressão em cada ponto, mas monitorizar a postura do cadeirante e aconselhá-lo a mudar de postura com regularidade, de modo a diminuir a probabilidade de ocorrência desta patologia. Ainda dentro desta aplicação, foi publicado um outro trabalho onde o sensor não só monitoriza a pressão como também a temperatura em cada um dos pontos de análise, conseguindo aferir assim indiretamente o cisalhamento. Numa outra fase, foi realizado o estudo e desenvolvimento de sensores de fibra ótica de plástico para monitorizar a postura corporal de um utilizador de uma cadeira de escritório. Simultaneamente, foi desenvolvido um software capaz de monitorizar e mostrar ao utilizador todos os dados adquiridos em tempo real e advertir o utilizador de posturas incorretas, bem como aconselhar para pausas no trabalho. Numa quarta fase, o estudo centrou-se no desenvolvimento de sensores altamente sensíveis embebidos em materiais impressos 3D. O sensor é composto por uma fibra ótica com uma FBG e o corpo do sensor por um material polimérico flexível, denominado “Flexible”. O sensor foi impresso numa impressora 3D e durante a sua impressão foi incorporada a fibra ótica. O sensor demonstrou ser altamente sensível e foi capaz de monitorizar frequência respiratória e cardíaca, tanto em soluções vestíveis (peito e pulso) como em soluções “invisíveis” (cadeira de escritório).Programa Doutoral em Engenharia Físic

    Casing structural integrity and failure modes in a range of well types: a review.

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    This paper focus on factors attributing to casing failure, their failure mechanism and the resulting failure mode. The casing is a critical component in a well and the main mechanical structural barrier element that provide conduits and avenue for oil and gas production over the well lifecycle and beyond. The casings are normally subjected to material degradation, varying local loads, induced stresses during stimulation, natural fractures, slip and shear during their installation and operation leading to different kinds of casing failure modes. The review paper also covers recent developments in casing integrity assessment techniques and their respective limitations. The taxonomy of the major causes and cases of casing failure in different well types is covered. In addition, an overview of casing trend utilisation and failure mix by grades is provided. The trend of casing utilisation in different wells examined show deep-water and shale gas horizontal wells employing higher tensile grades (P110 & Q125) due to their characteristics. Additionally, this review presents casing failure mixed by grades, with P110 recording the highest failure cases owing to its stiffness, high application in injection wells, shale gas, deep-water and high temperature and high temperature (HPHT) wells with high failure probability. A summary of existing tools used for the assessment of well integrity issues and their respective limitations is provided and conclusions drawn

    Proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress

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    Published proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress, hosted by York University, 27-30 May 2018

    Design, processing and characterisation of new optical fibre sensors for harsh environment.

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    L'abstract è presente nell'allegato / the abstract is in the attachmen

    Infusionsflügel - leicht, aber nicht einfach

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    Einen Segelflugzeugflügel im Infusionsverfahren herzustellen, klingt erst einmal gar nicht so schwierig. Wir nehmen uns ein Formwerkzeug, legen einen Lagenaufbau darauf ab, bringen ein paar Hilfsstoffe für die Vakuuminfusion auf, siegeln alles mit einer Vakuumfolie, evakuieren den Aufbau und lassen das Harz fließen. Der Rest geht dann von allein

    Eine virtuelle Zeitreise durch die vernetzte Produktion von morgen

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    Produktionsdaten müssen erfasst, verwaltet und in den richtigen Kontext gebracht werden, um Vergangenes rekapitulieren, Aktuelles beobachten und Zukünftiges nachhaltiger auslegen zu können. Die Fertigung soll nicht nur dokumentiert werden, um im Fall von Mängeln deren Ursache zu finden. Vielmehr sollen Maschinen ihre Soll- und Istwerte vernetzen und Abweichungen analysieren. Wissen und Erfahrungen von Mitarbeiterinnen und Mitarbeitern sollen digital erfasst und weitergegeben werden, um individuelle Abweichungen bei manuellen Prozessen zu vermeiden

    Rohrproben - ein pragmatischer Erkenntnisweg für den LH2-Tank

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    Wasserstoff ist eine vielversprechende Treibstoffoption für die kommende Generation von Verkehrsflugzeugen. An Bord wird er in flüssiger Form, d.h. kryogen, bei Temperaturen nahe dem absoluten Nullpunkt mitgeführt und als LH2 bezeichnet. Ein großer Tank ist notwendig mit sehr guter thermischer Isolation. Tank und Isolation erhöhen die strukturelle Masse. Das Gewicht eines Flüssigwasserstofftanks ist eine Material- und eine Optimierungsfrage. Eine besondere Herausforderung ist die Dichtigkeit: Wasserstoffmoleküle sind sehr klein und durchdringen (Permeation) jedes Tankmaterial mehr oder weniger schnell. Das Permeationsverhalten von Faserverbundstrukturen im Kontakt mit kryogenem Wasserstoff zu verstehen und messen zu können, ist daher für dessen sichere Handhabung von großer Bedeutung. Auf Basis dieser Erkenntnisse werden Materialien, Design und Fertigung des Tanks angepasst. Ein pragmatischer Ansatz wird mit der Fertigung von Rohrproben verfolgt, die zyklisch auf kryogene Temperatur abgekühlt und anschließend auf Dichtigkeit und auf Rissbildungen unter dem Mikroskop untersucht werden. So sind schnell grundlegende Erkenntnisse zu erlangen

    Was man nicht im KoPf hat, hinterlässt unnötige Fußabdrücke

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    Im Innovationszentrum für Kleinflugzeug-Technologien (INK) werden durch die DLR-Einrichtung Technologien für Kleinflugzeuge die Kompetenzen mehrerer DLR-Institute in der Städteregion Aachen räumlich zusammengeführt. 2021 starteten die ersten sechs Projekte unter Beteiligung von insgesamt 14 DLR-Instituten und -Einrichtungen sowie einigen externen Partnern, mit dem Ziel, den Luftverkehr der Zukunft zu erforschen, klimaverträgliche Technologien zu entwickeln und das emissions- und lärmreduzierte Fliegen zu ermöglichen. Eines dieser Projekte ist KoPf: „Kennwertdatenbank und optimierte Produktionstechnik für Kleinflugzeuge“. Darin wird der Übergang von der nachgeschalteten Qualitätssicherung einer statischen Produktionsumgebung zu einer „Ist-Daten“-basierten Qualitätsoptimierung in einem dynamischen Produktionsumfeld eingeleitet
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