abstract: All-dielectric self-supporting (ADSS) fiber optic cables are used for data transfer by the utilities. They are installed along high voltage transmission lines. Dry band arcing, a phenomenon which is observed in outdoor insulators, is also observed in ADSS cables. The heat developed during dry band arcing damages the ADSS cables' outer sheath. A method is presented here to rate the cable sheath using the power developed during dry band arcing. Because of the small diameter of ADSS cables, mechanical vibration is induced in ADSS cable. In order to avoid damage, vibration dampers known as spiral vibration dampers (SVD) are used over these ADSS cables. These dampers are installed near the armor rods, where the presence of leakage current and dry band activity is more. The effect of dampers on dry band activity is investigated by conducting experiments on ADSS cable and dampers. Observations made from the experiments suggest that the hydrophobicity of the cable and damper play a key role in stabilizing dry band arcs. Hydrophobic-ity of the samples have been compared. The importance of hydrophobicity of the samples is further illustrated with the help of simulation results. The results indi-cate that the electric field increases at the edges of water strip. The dry band arc-ing phenomenon could thus be correlated to the hydrophobicity of the outer sur-face of cable and damper. / Dissertation/Thesis / M.S. Electrical Engineering 2011

Les fuites au travers des ouvrages hydrauliques en remblai sont les signes précurseurs d'un dysfonctionnementdu dispositif d'étanchéité de l'ouvrage pouvant entraîner leur rupture. La détectionprécoce des fuites et leur quanti_cation est donc primordiale.Les méthodes géophysiques et thermométriques à grand rendement apportent des éléments deréponse pour la détection des fuites, le long des ouvrages à long linéaire, mais l'estimation de leurvitesse, nécessaire à l'évaluation de la dangerosité des fuites, n'est pas encore satisfaisante.Cette étude porte sur la détection et quanti_cation des fuites à travers les ouvrages hydrauliquesen remblai soumis à une charge d'eau permanente. Les méthodes proposées exploitent des mesures detempératures naturelles du sol à l'aide de _bres optiques placées sous le talus amont ou aval.Deux modèles de quanti_cation ont été développés et testés sur les données d'un site expérimentalcontrôlé et d'un site réel. Les résultats obtenus concordent avec les mesures de vitesse e_ectuées surles deux sites. / Leakages through embankment dams are early warning signs of a sealing malfunction and couldlead to its breakdown. Early detection of leakages and their quanti_cation is essential.High output geophysical and thermometric methods provide some answers for leakage detectionalong long linear embankment dams, but their velocity estimations necessary to assess the danger ofleakages, is not yet satisfactory.This study focuses on the detection and the quanti_cation of leakages through embankment damsunder hydraulic head. The proposed method use natural temperature measurements from the groundusing optical _ber buried under the upstream or downstream face.Two models of quanti_cation were developed and tested on data from an experimental site and a realsite. Results are consistent with velocity measurements made at both side.

Made available in DSpace on 2014-06-11T19:22:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-04-28Bitstream added on 2014-06-13T18:06:43Z : No. of bitstreams: 1 sakamoto_jms_me_ilha.pdf: 6608858 bytes, checksum: 00cb410d8ba756148ea0f5626f2c8f3b (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A interferometria a laser é uma técnica consolidada para a caracterização de atuadores piezoelétricos. No entanto, este método requer um alinhamento óptico preciso e uma operação meticulosa. Há um grande interesse no desenvolvimento de sistemas de medição de deslocamento e vibração usando sensores reflexivos em fibra óptica devido a sua inerente simplicidade, tamanho reduzido, largura de banda ampla, limite de detecção extremamente baixo e capacidade de realizar medições sem contato ou afetar o sistema a ser ensaiado. Neste trabalho apresenta-se um arranjo simples do sensor reflexivo para se atingir resolução sub-micrométrica, utilizando-se fibras e componentes ópticos de baixo custo e circuitos eletrônicos simples. O sistema é constituído por duas fibras ópticas adjacentes (uma transmissora e outra receptora) e com extremidades emparelhadas, posicionadas na frente de uma superfície reflexiva vibratória. A luz proveniente de uma fonte óptica (no caso um laser) é acoplada à fibra transmissora e parte dos raios refletidos pela superfície móvel é capturada pela fibra receptora, que conduz a luz para um fotodetector. A tensão de saída do fotodetector é função da distância entre as extremidades das fibras e a superfície reflexiva. Apresenta-se uma formulação teórica da função de intensidade óptica refletida no plano a uma distância qualquer, juntamente com comparações entre características experimentais e teóricas do sensor reflexivo. Finalmente, atuadores piezoelétricos flextensionais, projetados com o método de otimização topológica, são caracterizados experimentalmente através da medição de seus deslocamentos sub-micrométricos, utilizando o sensor reflexivo. As respostas em freqüência dos piezoatuadores flextensionais são levantadas e o fenômeno de erro de trajetória e linearidade são discutidos. / The laser interferometer method is a well-established technique for the characterization of piezoelectric actuators. However, this method requires precise optical alignment and meticulous operation. There is great interest in developing displacement and vibration measurement systems using reflective fiber optic displacement sensors (RFODS) because of their inherent simplicity, small size, wide frequency range, extremely low displacement detection limit, and ability to perform measurements without contact or affecting the vibrating system. This work presents a simple arrangement of RFODS to achieve sub-micrometer resolution, using low-cost fibers and optical components, and simple electronic circuits. The system is composed of two adjacent transmitting and receiving fibers at one end, located in front of a reflecting vibrating surface. The transmitting fiber is connected to a laser source, and part of the reflected rays by the moving surface is captured by the receiving fiber, which is connected to a light detector. The output voltage is a function of the distance between probe and vibrating surface. A theoretical formulation of the reflected light intensity function at distal end plane is presented, together with comparisons of experimental and ideal RFODS characteristics. Finally, piezoelectric flextensional actuators (PFAs), designed with the topology optimization method, are experimentally characterized by the measurement of their sub micrometric displacements using a RFODS. The frequency responses of the PFAs are evaluated, and the tracking error phenomenon and linearity are discussed.

Objetivos: Descrever a incidência de lesões laríngeas agudas após extubação em unidade de terapia intensiva pediátrica (UTIP), e avaliar os seus fatores de risco e sua relação com a presença de estridor pós-extubação. Delineamento: Coorte Prospectiva. Métodos: Foram elegíveis todas as crianças de zero a cinco anos incompletos internadas na UTIP do Hospital de Clínicas de Porto Alegre que necessitaram de intubação endotraqueal por mais de 24 horas. Foram excluídas aquelas com história de intubação, patologia laríngea prévia, presença de traqueostomia atual ou no passado, presença de malformações craniofaciais e consideradas terminais pela equipe assistente. As crianças incluídas foram acompanhadas diariamente e, após a extubação, foram submetidas à fibronasolaringoscopia (FNL). Resultados: Foram acompanhadas 202 pacientes entre novembro de 2005 e dezembro de 2012. Na FNL após a extubação, 88 pacientes (43,6%) apresentaram lesões laríngeas agudas moderadas ou graves. Após análise multivariada dos fatores de risco, verificamos que tais lesões estão associadas com a presença de balonete no tubo endotraqueal (TET), risco relativo de 1,42 (IC 95%: 1,02-1,97; P=0,039). Dos pacientes com lesões moderadas a graves, 21 (23.9%) tiveram estridor por mais de 72 horas (P<0,001). Houve associação estatisticamente significativa entre a persistência de estridor após 72horas e a presença de balonete no TET (P=0,036). Conclusões: Este estudo encontrou uma alta frequência de lesões laríngeas agudas após a extubação, que foram associadas com o uso de TET com balonete. Além disso, o estridor persistente após 72 horas da extubação foi mais frequente em pacientes que apresentaram lesões laríngeas e naqueles que usaram TET com balonete. / Objectives: To describe acute laryngeal injuries after extubation in a pediatric intensive care unit (PICU) and to assess risk factors and their association with post-extubation stridor. Design: Prospective cohort. Methods: Children aged zero to five years admitted to the PICU of Hospital de Clínicas de Porto Alegre who required endotracheal intubation for more than 24 hours were eligible for study. Patients with previous intubation, history of laryngeal disease, current or past tracheostomy, presence of craniofacial malformations and those considered terminal by the staff were excluded from the study. Children were monitored daily and underwent flexible fiber-optic laryngoscopy (FFL) after extubation. Results: We followed 202 children between November 2005 and December 2012. In the FFL after extubation, 88 children (43,6%) had moderate to severe laryngeal lesions. After multivariate analysis of potential risk factors, it was found acute lesions were associated with the presence of cuffed endotracheal tube (ETT), relative risk of 1,42 (CI 95%: 1,02-1,97; P=0,039). Among patients with moderate to severe laryngeal lesions, 21 (23,9%) had stridor for more than 72 hours (P<0,001). There was a statistically significant association between persistent stridor after 72 hours and the presence of the cuffed ETT (P=0,036). Conclusions: This study found high frequency of acute laryngeal injuries after extubation, which were associated with cuffed ETT. Moreover, persistent stridor after 72 hours of extubation was more frequent in patients with laryngeal lesions and in those who used cuffed ETT.

The development and transition of optical fiber sensors from experimental stage to practical applications largely depends on manufacturing cost and simplicity. To date, in-fiber grating sensors are largely manufactured by ultraviolet lasers despite higher fabrication cost and complexity. Besides, ultraviolet radiation can only write gratings in doped fibers. Therefore, reaping the benefits of existing fibers such as pure silica fiber, photonics crystal fibers etc. cannot be achieved using this technique. In contrast, uses of ultra-fast lasers have the potential to eliminate or minimize those drawbacks. However, extensive fabrication and packaging research is required for ultrafast laser technology to mature and offer grating based sensors fabrication in industrial scale. This dissertation presents design and fabrication of fiber optic sensors using femtosecond laser for measurement of ambient refractive index and temperature. The femtosecond laser operating at 780 nm with pulse duration of 172 fs and pulse repetition rate of 1 kHz is used to study bulk index modification and fabricate fiber long period and short period gratings. Effective and reliable fabrication of in-fiber gratings requires spatial control of refractive index written in optical fiber. With an aim to better control spatial index modulation in direct ultrafast writing, primary focus of this work is given to write single-shot submicron periodic voids in bulk glass. Femtosecond pulse filamentation in glass is studied to understand the morphology of bulk index change written by ultrashort pulses. Laser writing parameters (such as beam diameter, pulse energy, scanning speed, depth of focus, etc.) are then further tuned to write pulse filamentation induced refractive index change in optical fibers suitable for fiber grating fabrication. In order to design and tailor grating’s spectrum, measurement of in-fiber index is introduced in this work. We propose fiber Bragg grating based Fabry-Perot cavity structure (cavity length, L= 10 mm) to characterize femtosecond pulse filamentation induced refractive index change in the core of standard SMF. In addition, Mach-Zehnder interferometer (MZI) is proposed as an alternative yet effective and low cost tool to measure in-fiber index change. Comsol simulation is used to validate the quantification of index change. Measured index change is used in Optiwave simulation to design fiber long period gratings in standard telecommunication and pure silica core fibers. To increase fabrication reliability, we introduce inscription of helical long period gratings using a custom made rotary stage. Tapered photonic crystal and microfiber based Mach-Zehnder interferometer is also investigated for ambient refractive index measurement. Miniature fiber Bragg grating written in microfiber Mach-Zehnder interferometer is used in this work for multi-parameter sensing as well as temperature compensated refractive index sensing. Microfiber Bragg gratings buried in materials of higher thermal expansion coefficient is also proposed to significantly enhance temperature sensitivity. / Graduate / 0548, 0794, 0775 / fariduvic@gmail.com

Objetivos: Descrever a incidência de lesões laríngeas agudas após extubação em unidade de terapia intensiva pediátrica (UTIP), e avaliar os seus fatores de risco e sua relação com a presença de estridor pós-extubação. Delineamento: Coorte Prospectiva. Métodos: Foram elegíveis todas as crianças de zero a cinco anos incompletos internadas na UTIP do Hospital de Clínicas de Porto Alegre que necessitaram de intubação endotraqueal por mais de 24 horas. Foram excluídas aquelas com história de intubação, patologia laríngea prévia, presença de traqueostomia atual ou no passado, presença de malformações craniofaciais e consideradas terminais pela equipe assistente. As crianças incluídas foram acompanhadas diariamente e, após a extubação, foram submetidas à fibronasolaringoscopia (FNL). Resultados: Foram acompanhadas 202 pacientes entre novembro de 2005 e dezembro de 2012. Na FNL após a extubação, 88 pacientes (43,6%) apresentaram lesões laríngeas agudas moderadas ou graves. Após análise multivariada dos fatores de risco, verificamos que tais lesões estão associadas com a presença de balonete no tubo endotraqueal (TET), risco relativo de 1,42 (IC 95%: 1,02-1,97; P=0,039). Dos pacientes com lesões moderadas a graves, 21 (23.9%) tiveram estridor por mais de 72 horas (P<0,001). Houve associação estatisticamente significativa entre a persistência de estridor após 72horas e a presença de balonete no TET (P=0,036). Conclusões: Este estudo encontrou uma alta frequência de lesões laríngeas agudas após a extubação, que foram associadas com o uso de TET com balonete. Além disso, o estridor persistente após 72 horas da extubação foi mais frequente em pacientes que apresentaram lesões laríngeas e naqueles que usaram TET com balonete. / Objectives: To describe acute laryngeal injuries after extubation in a pediatric intensive care unit (PICU) and to assess risk factors and their association with post-extubation stridor. Design: Prospective cohort. Methods: Children aged zero to five years admitted to the PICU of Hospital de Clínicas de Porto Alegre who required endotracheal intubation for more than 24 hours were eligible for study. Patients with previous intubation, history of laryngeal disease, current or past tracheostomy, presence of craniofacial malformations and those considered terminal by the staff were excluded from the study. Children were monitored daily and underwent flexible fiber-optic laryngoscopy (FFL) after extubation. Results: We followed 202 children between November 2005 and December 2012. In the FFL after extubation, 88 children (43,6%) had moderate to severe laryngeal lesions. After multivariate analysis of potential risk factors, it was found acute lesions were associated with the presence of cuffed endotracheal tube (ETT), relative risk of 1,42 (CI 95%: 1,02-1,97; P=0,039). Among patients with moderate to severe laryngeal lesions, 21 (23,9%) had stridor for more than 72 hours (P<0,001). There was a statistically significant association between persistent stridor after 72 hours and the presence of the cuffed ETT (P=0,036). Conclusions: This study found high frequency of acute laryngeal injuries after extubation, which were associated with cuffed ETT. Moreover, persistent stridor after 72 hours of extubation was more frequent in patients with laryngeal lesions and in those who used cuffed ETT.

<p>U ovoj doktorskoj disertaciji dat je predlog nove metode za merenje talasne dužine monohromatske svetlosti pomoću spektralno osetljivih optičkih komponenti. Princip rada predložene metode se zasniva na kombinovanju spektralnih osetljivosti fiber-optičke račve i dva različita fotodetektora.<br />Izvršena je implementacija i karakterizacija senzorskog sistema za merenje talasne dužine monohromatske svetlosti. U eksperimentalnoj postavci korišćena je 2&times;2 fiber-optička račva, germanijumska (Ge) fotodioda i indijum-galijum-arsenid (InGaAs) fotodioda. Postignuta je linearnost sa faktorom korelacije R2=0.99942 i merna rezolucija od 17 pm u opsegu talasnih dužina svetlosti od 1575 do 1615 nm (L-opseg). U istom opsegu, dobijena je merna greška od približno &plusmn;0.2 nm i ponovljivost od &plusmn;0.16 nm. Ispitani su uticaji promena temperature, snage optičkog izvora i šuma na karakteristike senzorskog sistema.</p> / <p>In this thesis, a new method for measurement of monohromatic light<br />wavelength by using wavelength-dependent optical components is proposed.<br />The principle of operation of the proposed method is based on combining<br />spectral sensitivities of fiber-optic coupler and two different photodetectors.<br />Sensor system for measurement of monochromatic light wavelength is<br />implemented and characterized. Experimental setup consists of 2&times;2 fiberoptic<br />coupler, germanium (Ge) photodiode and indium-gallium-arsenide<br />(InGaAs) photodiode. Excellent linearity (R2=0.99942) and measurement<br />resolution of 17 pm are achieved in measurement range 1575-1615 nm (Lband).<br />In the same measurement range, measurement error of approximately<br />&plusmn;0.2 nm and repeatibility of &plusmn;0.16 nm are obtained. The influence of<br />temperature, optical source power and noise on sensor system characteristics<br />is investigated.</p>

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.

At present, the fiber optic ducts are connected by a mechanical type of joint. In this method, two ducts cut in the right angle are pushed in from both sides of the joint, and takes approximately one second to joint ducts together. The problem with the existing joint technology is that if there is water inside of the joint, it will be damaged when the water freezes into ice, and then may cause leakage. There is a risk of explosion when compressed air to blow the fiber. Thus, a joint protection device (silicone rubber sleeve) was developed to seal the joint for protection utterly. However, this will cause the larger size of the entire joint and limit the number of single-duct joints next to each other in a multi-duct joint. Fiber optic ducts are made of High-Density Polyethylene, which is the best plastic for remelting and can be welded by using the electro-fusion welding method. Based on the thermoplasticity of this material, this thesis developed a plastic joint with a built-in conductive metal wire inside. The applied voltage will heat the wire, then remelt the duct surfaces to weld them together through the joint. The welding system uses a portable battery operating system, so there is no need to connect it to the grid. To prevent the battery from being damaged by supplying too much current, a capacitor bank is used to store high energy for the preheating joints. The system uses a microcontroller to control and monitor current and voltage to ensure uniform heating of the metal wire. Theemphasisof this thesis isplacedon the implementation of basic experiments to run the welding system. Multiple welding experiments show that the welding system can manually set parameters to control the welding current of different joints, thereby ensuring the welding quality. Using a 2.5Ω joint to weld ducts will approximately consume 120J from the battery, so a fully charged 42V, 4.4AH rechargeable battery can perform almost 5600 times of welding. The suitable range of joint resistance will decrease as the required energy consumption increases/ the welding time decreases.

<p>U postupku praćenja stanja građevinskih struktura vr&scaron;i se nadzor nad fizičkim (mehaničkim), meteorolo&scaron;kim i hemijskim parametrima. U praksi se za merenje navedenih parametara koristi veliki broj instrumenata-senzora. Na osnovu uvida u aktuelno stanje iz oblasti istraživanja, zatim evidentne potrebe za istraživanjima o potencijalu postojećih i novih instrumenata i senzora za merenje geometrijskih deformacija i ekspanziji kori&scaron;ćenja fiber optičke senzorske tehnologije definisana je oblast istraživanja ove doktorske disertacije. U doktorskoj disertaciji izvr&scaron;eno je teorijsko i eksperimentalno istraživanje postojećih metoda za praćenje geometrijskih deformacija i razvoj sistema baziranog na fiber optičkom senzoru zakrivljenosti (eng. Fiber Optic Curvature Sensor &ndash; FOCS).</p> / <p>In the process of structural health monitoring (SHM) inspection of physical (mechanical), meteorological and chemical parameters is performed. In practice, a large number of instruments-sensors are used to measure these parameters. The field of research of this doctoral dissertation is based on the insight into the current state in the field of research, then the evident need for research on the potential of existing and new instruments and sensors for measuring geometric deformations and the usage expansion of fiber optic sensor technology. In the doctoral dissertation, theoretical and experimental study of the existing methods for monitoring geometric deformations and the development of a fiber optic curvature sensor (FOCS) system is performed.</p>