CAPES; FINEP; Fundação Araucária / O biodiesel desponta como uma das mais promissoras alternativas ambientalmente corretas aos combustíveis fósseis. A falta de um sensor apropriado para medir sua quantidade na mistura petrodiesel-biodiesel surge como uma grande oportunidade de pesquisa. Este trabalho apresenta um estudo sobre a fabricação e a caracterização de dispositivos intrínsecos a fibra ótica com o intuito de constituir um transdutor capaz de determinar a concentração de biodiesel presente em misturas petrodiesel-biodiesel. A gravação destes dispositivos, as redes de período longo, foi feita por meio da técnica de incidência lateral ponto-a-ponto de radiação ultravioleta oriunda de um laser Excímero de KrF operando em 248 nm. Na avaliação da sensibilidade ao índice de refração do meio externo às redes foram utilizados fluídos com índices de refração entre 1,00 e 1,47. Através de um processo de espelhamento aplicado na extremidade das fibras se obtém um tipo de dispositivo conhecido como CLPG. É feita a análise para a imersão da rede e da cavidade no mensurando, só da cavidade, assim como de porções da cavidade. Os dados mais promissores foram conseguidos com pequena porção da cavidade imersa em mistura petrodiesel-biodiesel, um caso em que é possível medir o índice de refração com relação à intensidade do sinal e inferir a proporção de cada componente na mistura. Ao final os parâmetros metrológicos do sistema foram apurados indicando boa confiabilidade, principalmente para a faixa de misturas B60 a B100. / The Biodiesel presents itself as one of the most promising environment friendly alternatives to the use of fossil fuels. The lack of a suitable sensor to measure the quality of biodiesel in the petrodiesel-biodiesel blend consists a great research opportunity. This work presents the implementation of a recording system of long period gratings, through the point-by-point technique of lateral exposure to ultraviolet radiation from a KrF Excimer laser operating at 248 nm, at Laboratório de Laser of UTFPR with the goal of producing a transducer that can quantify the proportion of petrodiesel and biodiesel blends through the changes in the refraction index. To evaluate the gratings sensitivity to the refraction index of the external environment, several liquids were used with refraction index ranging from 1.00 to 1.47. Through a reflective coating applied to the extremity of the fiber a kind of device usually called CLPG is obtained. A detail study of samples in contact with both the cavity and the grating, only with the cavity and finally with submerged portions of the cavity. The case of only a small party of the cavity immersed in the substance allows the measure of the refractive index related to signal strength. Finally, the metrological parameters of the system were evaluated indicating a good confiability, mainly for the B60 e B100 blends.

Orientador: Elnatan Chagas Ferreira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-20T12:19:42Z (GMT). No. of bitstreams: 1 Dante_Alex_M.pdf: 3529877 bytes, checksum: 4dd1be9e526e3698ffe5df07e12d5b62 (MD5) Previous issue date: 2012 / Resumo: Sensores a fibra óptica utilizando grades de Bragg em fibra (fiber Bragg grating - FBG) estão se tornando cada dia mais importantes, dada a quantidade de aplicações nas quais vêm sendo empregados. Algumas das principais características dos sensores a FBG são: imunidade à interferência eletromagnética (EMI), isolamento elétrico, baixo peso, flexibilidade, e transmissão de informações a longa distância. Eles estão sendo empregados na medida de temperatura, deformação, carga, tensão mecânica e vibração. Estão presentes também em estruturas inteligentes, onde sensores a FBG distribuídos são incorporados à estrutura, permitindo a monitoração em tempo real das condições estruturais de pontes, trilhos ferroviários e aviões. Este trabalho apresenta uma nova técnica de caracterização de FBGs utilizando deconvolução. Nesta técnica, utiliza-se uma FBG sintonizável, cujo perfil de reflexão é bem conhecido, para caracterização de outra FBG, cujo perfil é inicialmente desconhecido. Utilizando placas eletrônicas com componentes de baixo custo, e um software desenvolvido em LabVIEW®, no qual implementamos a deconvolução dos perfis das FBGs, essa técnica permite o levantamento do perfil de reflexão e outros parâmetros, como a largura espectral FWHM (do inglês Full Width at Half Maximum) e o comprimento de onda de Bragg 'lâmbda'B, de uma FBG. Os resultados obtidos tornaram possível a validação da técnica proposta e permitem concluir que ela é robusta e, com refinamentos matemáticos que podem ser implementados no processo de deconvolução, permite a construção de um caracterizador de FBGs preciso e de custo bem inferior a equipamentos disponíveis comercialmente / Abstract: Optical fiber sensors using fiber Bragg gratings (FBG) are becoming increasingly important, given the amount of applications in which they are being used. Some of the most important characteristics of FBGs are: electromagnetic interference (EMI) immunity, light weight, flexibility, and long range information transmission. FBG sensors are being used in the measurement of temperature, deformation, load, strain and vibration. They are also being used in smart structures, where several distributed sensing FBGs are embedded in materials to allow for the real-time monitoring of the structural conditions of bridges, railroad tracks and airplanes. A new technique for the FBGs characterization using deconvolution is presented. In this technique, a tunable FBG, whose reflection spectrum is known, is used to discover another FBGs profile, which is previously unknown. Using low-cost electronic parts and software developed in LabVIEW, which performs the deconvolution of both FBGs spectra, this technique allows the measurement of the FBG reflection spectrum, its FWHM (Full Width at Half Maximum), and the Bragg center wavelength 'lambda'B. The obtained results enables to validate the proposed technique, allowing concluding that it is robust and, if numerical refinement is implemented, it will be possible to build a low-cost FBG characterization device, in comparison with other commercial devices used for this purpose / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

Indiana University-Purdue University Indianapolis (IUPUI) / A key component in tracking is identifying relevant data and combining the data in an effort to provide an accurate estimate of both the location and the orientation of an object marker as it moves through an environment. This thesis proposes an enhancement to an existing tracking system, the enhanced distributed tracking system (e-DTS), in the form of the e-DTS 2.0 and provides an empirical analysis of these enhancements. The thesis also provides suggestions on future enhancements and improvements. When a Camera identifies an object within its frame of view, it communicates with a JINI-based service in an effort to expose this information to any client who wishes to consume it. This aforementioned communication utilizes the JINI Multicast Lookup Protocol to provide the means for a dynamic discovery of any sensors as they are added or removed from the environment during the tracking process. The client can then retrieve this information from the service and perform a fusion technique in an effort to provide an estimation of the marker's current location with respect to a given coordinate system. The coordinate system handoff and transformation is a key component of the e-DTS 2.0 tracking process as it improves the agility of the system.

An optical fiber sensor is used for identification of a cantilevered beam under conditions of various concentrated mass loadings. A model of the sensor as well as the dynamic system is developed and used to test the reliability of the identification. Input/output data from an experiment is gathered and used in the identification. A survey of the existing areas of damage detection and parameter identification is included, along with suggestions for incorporating fiber optic sensors into existing techniques. The goal of this research was to show that the fiber sensor can be used for identification purposes, and that it is sensitive to parameter changes within the system (in this case concentrated mass changes). / Master of Science

Several techniques for measuring high frequency vibrations are presented. The goal of the study is to develop a sensor for detecting acoustic emissions (AE) inside composite structures. The basics of wave propagation inside of materials has been presented along with an overview of typical acoustic emission testing. Surface acoustic waves (SAWs) were studied first and a novel, noncontact optical interferometric technique for measuring absolute amplitudes is presented. This technique has the added advantages in that it does not require that the interferometer be stabilized or phase biased. It is insensitive to laser fluctuations, random phase drifts, polarization changes and changes in mixing efficiency of the interferometer. SAW amplitudes between 7 and 2.5 angstroms were measured with the described technique. An intrinsic Fabry-Perot type interferometer was demonstrated for detecting SAW's and was then embedded into carbon fiber composite panels which were then put through tensile tests. AE's were captured, centered around 300 KHz, as is expected of a composite. These tests were repeatable and indicate that qualitative measurements of AE can be made. This sensor configuration was also used for detecting a variety of taps on the composite panel as well as pencil lead breaks, a standard calibration procedure for AE testing. / Master of Science

The detection and active monitoring of hydrogen gas levels is essential in many areas of industry including manufacturing, storage, and transport of this gas. Previously, methods used to detect hydrogen gas have relied upon monolithic technologies to create resistive-based sensors which are impractical for many applications requiring electrical isolation or operation in the presence of strong electromagnetic fields. Materials can be sputter deposited along cylindrical optical fiber-based sensors to create novel fiber-optic chemical sensors. Herein, the mechanisms allowing the detection of hydrogen gas using a modified Extrinsic Fabry-Perot Interferometric (EFPI) sensor are presented in this work. A new custom-designed, custom-built radio frequency (RF) magnetron sputtering system has been used to deposit thin films of palladium metal along with cylindrical substrates. The surface morphology of the deposited films are investigated using a variety of analytical tools, including Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (AES), and Auger Electron Spectroscopy (AES). The system is used to deposit thin films of palladium along a cylindrical EFPI fiber-optic sensor to produce a new fiber-optic hydrogen gas sensor. Experimental results obtained in a controlled hydrogen atmosphere are used to demonstrate the high resolution and fast response time associated with these new hybrid sensors. / Master of Science

The use of optical sensors to perform health monitoring in fault-tolerant multicomputers can allow the multicomputer to detect imminent failure in a particular section of the interconnection network due to damaging strain. This detection method allows the rerouting of critical data before data link failure occurs. This thesis investigates the implementation of the extrinsic Fabry-Perot interferometer into an optical hybrid communications/sensing network. A testbed of personal computers, acting as nodes of a multicomputer, are used to monitor the integrity of the network to a high degree of accuracy. When a node determines that an adjacent data link is no longer reliable due to physical damage, communications are rerouted and the node is shut down. Results of experiments with the testbed have shown that redundant nodes can be used to share computational loads, increasing the performance of the multicomputer, until network failure forces redundant nodes to assume full responsibility for computational tasks. Multicomputer performance suffers as a result of network damage, but full functionality is retained with no occurrence of errors or unknown conditions due to data link failure. / Master of Science

A liquid core fiber sensor can be used to sense both strain and temperature simultaneously. This liquid core fiber sensor is comprised of a hollow core optical fiber filled with a liquid of a known index of refraction which is slightly higher than that of the silica tube which acts as the cladding. The refractive index fluid is chosen such that the variation of its refractive index with strain and temperature is well defined and linear in the desired range of operation. The core of the sensing fiber contains a fluid which has a thermo-optic coefficient much larger in magnitude (-4.0x10⁻⁴/°C) than that of the silica cladding. This causes the fiber to be more sensitive to temperature changes than all-silica fibers. Both transmitted optical signal intensity and time-of-flight depend strongly on applied strain and temperature. Furthermore, the relative difference between the core and cladding refractive indices changes as a function of both parameters due to the inherently different material types used in the fiber construction. This results in critical strain and temperature regimes within which the refractive index difference is very small, and sensitivity is optimized. Testing of prototype sensors demonstrates these characteristics. A 0.47 m long liquid core fiber containing a liquid with a room temperature refractive index of 1.492 was analyzed. Both time- and intensity-domain behaviors around the device's critical temperature (95°C) confirm theoretical expectations. Simultaneous strain and temperature measurements were performed between 95 °C and 105 °C. Methods for multiplexing liquid core fibers for increasing the range of temperatures that can be monitored were also investigated as well as using those liquid core fibers for cooling purposes. / Master of Science

No description available.

The use of optical fiber is of great interest in developing extensive, high-speed networking infrastructures. Optical fiber provide many advantages over traditional copper cables and wireless links. Among them are high security, low electromagnetic interference, extremely low loss and high bandwidths, light weight and manageability. However, the very small wavelengths associated with optical radiation requires very small waveguide dimensions. Waveguide dimension of single mode fiber (SMF) are < 10µm, resulting in relatively poor yield in device manufacturing. For residential and other last-mile networks topologies, cost constraints limit the appeal of SMF. Multimode fiber (MMF) allow for less restrictive manufacturing tolerances; however, the distortion that results from the dispersion in propagation among the many modes can be prohibitively large for data rates approaching and exceeding 1 Gb/s. To improve the deployability of MMF, a method of dispersion compensation that maintains the ease-of-use characteristic of MMF is required This dissertation demonstrates an opto-electronic method of dispersion compensation by the use of a multisegment photodetector. It is shown the modes of the fiber can be seperated such that when the individual photodetector signals are combined, the resulting temporal response of the fiber link is improved from that of a conventional fiber link. This method is extremely robust to system variation and is independent of data rate and transmission format, allowing it to be employed in a wide variety of optical links. More importantly, the implementation demonstrated is comparable, in simplicity and alignment tolerance, to a conventional photodetector. System performance is shown using both temporal and frequency response as well as real bit error rate and eye diagram measurements.