O transformador de potência é um importante equipamento utilizado no sistema elétrico de potência, responsável por transmitir energia elétrica ou potência elétrica de um circuito a outro e transformar tensões e correntes de um circuito elétrico. O transformador de potência tem ampla aplicação, podendo ser utilizado em subestações de usinas de geração, transmissão e distribuição. Neste sentido, mudanças recentes ocorridas no sistema elétrico brasileiro, causadas principalmente pelo aumento considerável de carga e pelo desenvolvimento tecnológico tem proporcionado a fabricação de um transformador com a aplicação de alta tecnologia, aumentando a confiabilidade deste equipamento e, em paralelo, a redução do seu custo global. Tradicionalmente, os transformadores são fabricados com um sistema de isolação que associa isolantes sólidos e celulose, ambos, imersos em óleo mineral isolante, constituição esta que define um limite à temperatura operacional contínua. No entanto, ao se substituir este sistema de isolação formado por papel celulose e óleo mineral isolante por um sistema de isolação semi- híbrida - aplicação de papel NOMEX e óleo vegetal isolante, a capacidade de carga do transformador pode ser aumentada por suportar maiores temperaturas. Desta forma, o envelhecimento do sistema de isolação poderá ser em longo prazo, significativamente reduzido. Esta técnica de aumentar os limites térmicos do transformador pode eliminar, essencialmente, as restrições térmicas associadas à isolação celulósica, provendo uma solução econômica para aperfeiçoar o uso de transformadores de potência, aumentando a sua confiabilidade operacional. Adicionalmente, à aplicação de sensores de fibra óptica, em substituição aos sensores de imagem térmica no monitoramento das temperaturas internas do transformador, se apresentam como importante opção na definição do equacionamento do comportamento do transformador sob o ponto de vista térmico. / The power transformer is important equipment used in electric power system, which is responsible for transmitting electricity or electric power from one circuit to another, transforms voltage and current in an electrical circuit. Moreover, it has wide application and can be used in substations of power plants, transmission and distribution. Recent changes in the electrical system caused mainly by the considerable increase in load and technological development provided by the manufacture of a transformer with the application of high technology, increasing the reliability of this equipment and, in parallel, reducing their overall cost. Traditionally, transformers are manufactured with a solid insulation system that combines solid insulation and cellulose, both immersed in oil, this constitution which limits the continuous operating temperature. However, when replacing this insulation system consisting of paper and cellulose insulating oil by a hybrid system consisting - application paper NOMEX and vegetable oil, the capacity of the transformer can be substantially increased. Thus, the aging of the insulation system may be at long term, significantly reduced. This technique of increasing the thermal limits of the equipment can essentially eliminate thermal constraints associated with conventional insulation, providing an economical solution for the optimization of power transformers, increasing their operational reliability. Additionally, the application of fiber-optic sensors, replacing the thermal imaging sensors to monitor the internal temperature of the transformer is presented as an important option in the definition of the equation of transformer behavior under the thermal point of view.

This dissertation demonstrates the design of reversibly self-morphing novel liquid crystalline elastomer (LCE) antennas that can dynamically change electromagnetic performance in response to temperature. This change in performance can be achieved by programming the shape change of stimuli-responsive (i.e., temperature-responsive) LCEs, and using these materials as substrates for reconfigurable antennas. Existing reconfigurable antennas rely on external circuitry such as Micro-Electro-Mechanical-Systems (MEMS) switches, pin diodes, and shape memory alloys (SMAs) to reconfigure their performance. Antennas using MEMS or diodes exhibit low efficiency due to the losses from these components. Also, antennas based on SMAs can change their performance only once as SMAs response to the stimuli and is not reversible. Flexible electronics are capable of morphing from one shape to another using various techniques, such as liquid metals, hydrogels, and shape memory polymers. LCE antennas can reconfigure their electromagnetic performance, (e.g., frequency of operation, polarization, and radiation pattern) and enable passive (i.e., battery-less) temperature sensing and monitoring applications, such as passive radio frequency identification device (RFID) sensing tags. Limited previous work has been performed on shape-changing antenna structures based on LCEs. To date, self-morphing flexible electronics, including antennas, which rely on stimuli-responsive LCEs that reversibly change shape in response to temperature changes, have not been previously explored. Here, LCE antennas will be studied and developed. Also, the metallization of LCEs with different metal conductors and their fabrication process, by either electron beam (E-Beam) evaporation or optical gluing of the metal film will be observed. The LCE material can have a significant impact on sensing applications due to its reversible actuation that can enable a sensor to work repeatedly. This interdisciplinary research (material polymer science and electrical engineering) is expected to contribute to the development of morphing electronics, including sensors, passive antennas, arrays, and frequency selective surfaces (FSS).

The nuclear industry shows an increasing interest in the fiber optic technology for both data communication and sensing applications in nuclear plants. The optical fibers offer several advantages and the sensors based on this technology do not need any electrical power at the sensing point, they have a quick response and they can be easily multiplexed: in the case of a temperature sensor, several thermocouples can be substituted by a single fiber, resulting in a decrease of the waste material. The fission reactors are a very harsh environment: it is characterized by the highest dose of gamma-rays, of the order of magnitude of GGy, besides a high flux of neutrons and high operating temperature (300°C for the current reactors, known as generation III). This work has been carried out in collaboration with AREVA, a French industrial conglomerate active in the energy domain, with the aim of realizing a temperature sensor resistant to the environment of nuclear reactor of generation IV, in particular a Sodium-cooled Fast Reactor. The currently used technology, the thermocouples, presents a drift of the measurement due to irradiation, that needs a calibration, and a long response time on the order of seconds. In order to remove the drift, to reduce the response time and to increase the precision, a Fiber Bragg Grating temperature sensor was chosen, in regard to all the advantages of the optical fibers. To understand the behavior of such system in a harsh environment, as the nuclear reactor core, we used an experimental approach based on complementary techniques such as radiation-induced attenuation, photoluminescence, electron paramagnetic resonance and Raman spectroscopies

Esta tese apresenta o desenvolvimento de uma técnica de processamento numérico capaz de reconstruir o sinal da temperatura do processo original a partir do sinal distorcido, atrasado e ruidoso, medido através de uma sonda intrusiva. Uma técnica de regularização foi adotada para contornar o mau condicionamento do modelo numérico inverso da equação de transdução para obter o sinal do processo, que considera o acúmulo térmico e as transferências de calor convectivo e radiativo entre o meio e o sensor térmico. O método dos mínimos quadrados simplificado foi implementado como técnica de regularização, por ser um método rápido e possuir um código computacional pequeno, permitindo, obter os dados em tempo real e desenvolver um sensor térmico inteligente. Testes numéricos demonstraram as discrepâncias introduzidas pela inércia térmica, convecção e radiação, bem como a extrema sensibilidade da presença de ruídos quando o problema inverso é resolvido. Testes experimentais foram conduzidos para validar o algoritmo de reconstrução sob condições práticas com sinais obtidos por um termopar encapsulado / This thesis presents the development of a numerical processing technique capable of reconstructing the original process temperature signal from distorted, late and noisy measured signal obtained from an intrusive probe. A regularization technique was adopted to palliate the ill conditioning of the inverse numerical model of the transduction equation to obtain the process signal, which considers thermal accumulation and convective and radiative heat transfers between the medium and the thermal sensor. The simplified least square method was implemented as the regularization technique, because it is a fast method and results in a small computational code, which produces on-line information and allow the development an intelligent temperature sensor. Numerical tests demonstrated the discrepancies introduced by thermal inertia, convection and radiation, as well as the extreme sensitivities to the presence of noise when solving the inverse problem. Experimental tests were carried out to validate the reconstruction algorithm under realistic experimental conditions with the signals obtained by the sheathed thermocouple

Abstract The target in this thesis was to study selected special measurements in a basic oxygen furnace (BOF) and develop a model to predict the steel temperature at the end of the oxygen blow. Furthermore, the work aimed at increasing knowledge on measurements and phenomena in the converter and in this way improve the possibility of more efficient monitoring and control of the process. Special measurements were investigated to obtain more knowledge about their usability in running the converter process. Analysing the measurement results also led to new process knowledge. The usage of a Radio Wave Interferometer (RWI) was seen as beneficial as it makes it possible to see the rising trend of the liquid surface level in advance and to perform some corrective actions to avoid excessive foaming and possible splashing out from the converter. Acoustic measurement could also detect trends in advance, but it was found to be sensitive to disturbing noise from the surroundings. Splashing measurement gives information about the current state of the slag but not advance information. Nevertheless, the measurements revealed several factors that usually increase splashing. It would be best to use the knowledge from two different measurements, for example RWI and splashing measurement, to predict increasing splashing, which causes significant iron losses. The development of the models for end temperature prediction and additional materials provided a lot of knowledge about the factors affecting the temperature. Factors that were used in grouping were the BOF number, heat size and end carbon content. However, there were many heats that did not satisfy the target. Furthermore, there is a need for additional research into temperature progress and its control in BOF. It would also be useful to study the effect of additional materials more systematically. There are other factors, such as the oxygen flow rate and lance height, which affect the temperature that are not included in the models. Some of the factors are measurable and some are not. There is still a need for more research in this area. This work strengthens the impression that the converter process is a complex one. It was noticed; as always in process development, that continuous monitoring and efforts are required to observe the changes in process conditions, raw materials or running practices. Otherwise, the benefit of the improvements and models will be lessened. However, it would be possible to set acknowledged routines and warnings into the improved monitoring system to help the operators notice the need for system tuning. A monitoring system would provide financial benefits in terms of having fewer reblowings, better yield and better quality of final product. Savings in raw materials can also be attained as the controllability of the process becomes better. As the monitoring system contains a database of guidelines, it would form a good basis for new employees to become familiar with the process and thus facilitate their training. / Tiivistelmä Tämän opinnäytteen tarkoitus oli tutkia teräskonvertterin valittuja erikoismittauksia ja kehittää malli ennustamaan teräksen lämpötilaa happipuhalluksen lopussa. Työn tarkoituksena oli lisätä tietämystä mittauksista ja ilmiöistä konvertterissa ja tällä tapaa lisätä mahdollisuuksia prosessin tehokkaampaan monitorointiin ja ohjaukseen. Erikoismittauksia tutkittiin lisätietämyksen saamiseksi niiden käytettävyydestä konvertteriprosessin ajossa. Mittausten analysointi tuotti myös uutta prosessitietämystä. Radioaaltointerferometrin (RWI) käyttö koettiin hyödylliseksi, koska on mahdollista havaita kuonan pinnankorkeuden nousu ennakkoon ja suorittaa joitakin korjaavia toimenpiteitä liiallisen kuohumisen ja lopulta roiskumisen estämiseksi ulos konvertterista. Äänimittaus voi myös havaita trendin ennakkoon, mutta huomattiin sen olevan herkkä ympäristön häiriöäänille. Roiskemittaus antaa tietoa kuonan sen hetkisestä tilasta, mutta ei ennakkoon. Mittaukset toivat kuitenkin esiin useita tekijöitä, jotka yleensä lisäävät roiskumista. Olisi parasta käyttää kahden eri mittauksen tietoa, RWI ja roiskemittaus, ennustettaessa lisääntyvää roiskumista, joka aiheuttaa huomattavia rautahäviöitä. Loppulämpötilan ennustamiseen kehitetyn mallin ja lisäainemallin kehittäminen antoi paljon tietoa tekijöistä, jotka vaikuttavat lämpötilaan. Tekijät, joita käytettiin ryhmittelyssä, olivat konvertterinumero, panoskoko ja loppuhiilipitoisuus. Mallin soveltamisesta huolimatta jäi edelleen useita sulatuksia, jotka eivät osuneet tavoitteeseen. On edelleen tarve teräskonvertterin lämpötilakäyttäytymisen ja sen hallinnan lisätutkimukselle konvertterissa. Myös lisäaineiden vaikutusta lämpötilaan olisi hyödyllistä tutkia systemaattisemmin. On edelleen muita tekijöitä, esimerkiksi hapen virtausnopeus ja lanssin korkeus, jotka vaikuttavat lämpötilaan, mutta jotka eivät ole mukana malleissa. Osa näistä tekijöistä on mitattavia suureita ja osa ei. Lisätutkimukselle on edelleen tilaa tällä alueella. Tämä työ vahvistaa edelleen käsitystä, että konvertteriprosessi on monimutkainen. Huomattiin, kuten aina prosessikehityksessä, että jatkuvaa kehitystyötä pitää tehdä prosessiolosuhteiden, raaka-aineiden ja ajopraktiikoiden muutosten huomaamiseksi. Muuten parannusten ja mallien antama hyöty heikkenee. Monitorointijärjestelmään olisi mahdollista kehittää rutiineja ja varoituksia operaattorien avuksi, jotta he huomaisivat järjestelmävirityksen tarpeen. Monitorointijärjestelmä toisi taloudellista hyötyä, mm. lisäpuhallusten vähentymisen, lopputuotteen paremman saannon ja laadun muodossa. Raaka-ainesäästöjä voidaan saavuttaa prosessin ohjattavuuden parantuessa. Monitorointijärjestelmän sisältäessä sääntötietokannan, se luo hyvän pohjan uusille työntekijöille tutustua prosessiin ja näin heidän koulutuksensa onnistuisi helpommin.

L'industrie nucléaire montre un intérêt croissant pour les technologies basées sur les fibres optiques pour la transmission des données et comme capteurs. Les fibres optiques offrent plusieurs avantages et les capteurs utilisant cette technologie n'ont pas besoin d'alimentation électrique au point de détection, ils ont une réponse rapide et peuvent être facilement multiplexés : dans le cas d'un capteur de température plusieurs thermocouples peuvent être substituées par une seule fibre, diminuant les déchets. Les réacteurs à fission nucléaire constituent un des environnements les plus agressifs : la dose de rayonnement gamma est de l'ordre du GGy avec une forte fluence de neutrons et une température de fonctionnement supérieure à 300°C pour les réacteurs actuels, connus comme de génération III. Ce travail a été réalisé en collaboration avec la société AREVA, industriel français actif dans le domaine de l'énergie, dans le but de réaliser un capteur de température résistant à l'environnement d'un réacteur nucléaire de génération IV, réacteur à neutrons rapides refroidi au sodium liquide. La technologie actuellement utilisée, les thermocouples, présente une dérive de la mesure due au rayonnement et un temps de réponse d'une seconde. Afin de supprimer la dérive, de réduire le temps de réponse et d'augmenter la précision, un capteur de température à réseau de Bragg a été choisi. Pour comprendre le comportement d'un tel système dans un environnement difficile, nous avons utilisé une approche expérimentale basée sur des techniques complémentaires comme l'atténuation induite par le rayonnement, photoluminescence, résonance paramagnétique électronique et spectroscopie Raman / The nuclear industry shows an increasing interest in the fiber optic technology for both data communication and sensing applications in nuclear plants. The optical fibers offer several advantages and the sensors based on this technology do not need any electrical power at the sensing point, they have a quick response and they can be easily multiplexed: in the case of a temperature sensor, several thermocouples can be substituted by a single fiber, resulting in a decrease of the waste material. The fission reactors are a very harsh environment: it is characterized by the highest dose of gamma-rays, of the order of magnitude of GGy, besides a high flux of neutrons and high operating temperature (300°C for the current reactors, known as generation III). This work has been carried out in collaboration with AREVA, a French industrial conglomerate active in the energy domain, with the aim of realizing a temperature sensor resistant to the environment of nuclear reactor of generation IV, in particular a Sodium-cooled Fast Reactor. The currently used technology, the thermocouples, presents a drift of the measurement due to irradiation, that needs a calibration, and a long response time on the order of seconds. In order to remove the drift, to reduce the response time and to increase the precision, a Fiber Bragg Grating temperature sensor was chosen, in regard to all the advantages of the optical fibers. To understand the behavior of such system in a harsh environment, as the nuclear reactor core, we used an experimental approach based on complementary techniques such as radiation-induced attenuation, photoluminescence, electron paramagnetic resonance and Raman spectroscopies

O processo de conversão ascendente de energia (infravermelho ao visível) é amplamente estudado em materiais dopados com íons terras raras trivalentes (TR3+) devido as várias possibilidades de aplicações tecnológicas. Tal processo consiste na emissão de fótons de maior energia (usualmente no visível) mediante excitação com fótons de menor energia (infravermelho) via mecanismo de absorção de dois fótons e/ou transferência de energia entre os íons TR3+. Entre os materiais estudados destacam-se vidros e vitrocerâmicas dopados com Er3+ com emissões nas regiões do verde e do vermelho, que podem ser eficientemente excitadas por lasers de diodo na região do infravermelho próximo (980 nm). Uma das aplicações possíveis para este processo é a de um sensor óptico de temperatura baseado na dependência da razão de intensidades de emissão dos níveis 2H11/2 e 4S3/2 do Er3+ com a temperatura, vantajoso para operação em ambientes hostis como transformadores de alta tensão, em processos industriais, etc. Como a eficiência das emissões depende também da matriz hospedeira, os vidros fluorofosfatos com composição 25BaF225SrF2(30-x)Al(PO3)3xAlF3(20-z)YF3:zErF3 com x = 20 e z = 1,0 a 5,0 mol% foram escolhidos por apresentarem alta estabilidade química e mecânica, e energia de fônon relativamente baixa. Assim, amostras vítreas dopadas com várias concentrações de Er3+ foram previamente caracterizadas e selecionadas para desenvolver o protótipo que emprega a variação de intensidade relativa das emissões 2H11/2 → 4I15/2 e 4S3/2 → 4I15/2 do vidro fluorofosfato dopado com Er3+ na medição de temperaturas. Este protótipo apresenta as características de baixo custo, alta sensibilidade e rápida resposta. / The infrared-to-visible upconversion process is widely studied in materials doped with trivalent rare earth ions (RE3+) due to the various possibilities of technological applications. The process is based on the emission of photons with higher energy (in the visible) than the excitation photons (in the infrared) via the mechanisms of two-photon absorption and/or energy transfer between RE3+ ions. Among the studied materials emphasis is given to glasses and glass ceramics doped with Er3+, exhibiting intense emissions in the green and red, which can be efficiently excited by diode lasers in the near infrared region (980 nm). One application of this process is an optical temperature sensor based on the dependence of the ratio of the emission intensities of levels 2H11/2 and 4S3/2 of Er3+ on the temperature of the sample. Such sensor would be advantageous for operation in hostile environments, such as high voltage transformers, industrial processes, etc. Because the efficiency of upconversion also depends on the host matrix composition, flurophosphate glasses are interesting candidates due to their high chemical stability, good mechanical properties and relatively low phonon energy. Glasses with composition 25BaF225SrF2(30-x)Al(PO3)3xAlF3(20-z)YF3:zErF3 with x = 20 and z varying from 1.0 to 5.0 mol% were characterized and selected to develop the prototype employing the fluorescence of fluorophosphate glass doped with Er3+ for measuring temperatures with the following characteristics: low cost, high accuracy and fast response.

This work explores the blending of e-textile technology with the porous electrode of polymer electrolyte membrane fuel cells (PEMFCs) and with smart wound patches to allow monitoring and in-situ diagnostics. This work includes contributions to understanding water transport and conductivity in the carbon cloth gas diffusion layer (GDL), and further developing thread-based relative humidity (RH) and temperature sensors, which can be sewn on a cloth GDL in PEMFCs. We also explore the application of the developed RH and temperature sensors in wearable biomonitoring. First, an experimental prototype is developed for evaluating water transport, thermal conductivity and electrical conductivity of carbon cloth GDLs under different hydrophobic coatings and compressions. Second, we demonstrate the addition of external threads to the carbon cloth GDL to (1) facilitate water transport and (2) measure local RH and temperature with a minimal impact on the physical, microstructural and transport properties of the GDL. We illustrate the roll-to-roll process for fabricating RH and temperature sensors by dip-coating commodity threads into a carbon nanotubes (CNTs) suspension. The thread-based sensors response to RH and temperature in the working environment of PEMFCs is investigated. As a proof-of-concept, the local temperature of carbon cloth GDL is monitored in an ex-situ experiment. Finally, we optimized the coating parameters (e.g. CNTs concentration, surfactant concentration and a number of dipping) for the thread-based sensors. The response of the thread-based sensors in room conditions is evaluated and shows a linear resistance decrease to temperature and a quadratic resistance increase to RH. We also evaluated the biocompatibility of the sensors by performing cell cytotoxicity and studying wound healing in an animal model. The novel thread-based sensors are not only applicable for textile electrochemical devices but also, show a promising future in wearable biomonitoring applications. / Graduate

[pt] A presente tese tem por objetivo estabelecer uma metodologia de caracterização metrológica de redes de Bragg do tipo I, tipo II e tipo regenerada estimando e validando estatisticamente o resultado de medição para medições de altas temperaturas voltadas para aplicações em sensoriamento. Além das telecomunicações, as fibras óticas estão sendo empregadas em aplicações de sensoriamento, visto que, a sílica que as compõem apresenta grande eficiência como meio de transmissão de dados. A crescente demanda por medição em alta temperatura nos processos industriais possibilitou o desenvolvimento de novas tecnologias de medição além das tecnologias tradicionais já utilizadas atualmente. Desta forma, criaram-se as condições necessárias para se introduzir uma nova tecnologia de medição de temperatura com redes de Bragg que apresenta algumas vantagens se comparadas com as tecnologias tradicionais de medição. Apesar de já existirem várias pesquisas a respeito de medição de temperatura com redes de Bragg, nenhuma delas aprofundou as questões metrológicas com as respectivas estimativas das incertezas de medição que envolve todo o processo de medição e caracterização de redes de Bragg em alta temperatura. A adaptação de um sistema tradicional de calibração de instrumentos de medição de temperatura foi projetado e desenvolvido, de tal forma que possibilitou a caracterização dos diferentes tipos de redes. Observou-se que os resultados de medição e as estimativas das incertezas de medição obtidos para todas as redes, se aproximaram satisfatoriamente dos modelos teóricos utilizados, confirmando a adequação dos sistemas de medição de temperatura e sensoriamento ótico. / [en] This thesis aims to establish a methodology for the metrological characterization of Bragg gratings type I, type II and type regenerated statistically thereby estimating and validating the measurement results for high temperature sensing applications. Beyond telecommunications applications, optical fibers are still used for optical sensing, since the silica fiber has great optical efficiency for data transmission. The growing demand for high-temperature measurements in industrial processes has enabled the development of new measurement technologies beyond the traditional technologies already in use today. Thus were created the conditions necessary to introduce a new technology of temperature measurement with Bragg gratings which presents some advantages compared with traditional technologies of measurement. Although there are several prior studies none of those examined the by others about temperature measurement with Bragg gratings, metrological issues, and is particular, the estimate of the measurement uncertainties surrounding the whole process of measurement and characterization of Bragg gratings at high temperature. The adaptation of a traditional system of calibration instruments for temperature measurement was developed and designed in such a way that allowed the characterization of different types of gratings. It was observed that the measurement results and the estimated uncertainties of the measurements obtained for all gratings, successfully approached the theoretical models used, confirming the adequacy of the measurement of temperature and optical sensing.

This master's thesis deals with the measurement of soil temperature. In the theoretical part, optical fiber systems were explained, with a focus on DSTS systems and their use. In the practical part, a functional system was created to measure the soil temperature at depths of 0.1-1~m using the Arduino platform. Furthermore, the temperature measurement was demonstrated on the test polygon using the optical fiber of the FTB 2505 instrument in laboratories.