Thesis (Ph.D.)--York University, 2007. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 167-176). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR32057

Thesis(M.S.)--Auburn University, 2006. / Abstract. Includes bibliographic references (p.67-68).

Gas turbines are widely used in power generation. Monitoring pressure variations in the combustion chamber allows for real-time assessment of the turbines performance, and can be used to optimize combustion processes, leading to reduced emissions. By analyzing pressure, patterns, potential faults or degradation in critical components can be identified, enhancing the safety and reliability of the gas turbine. Measurements close to the combustion flame put high demands on the pressure sensors and their verification method. The aim of this thesis is thus to create an automated pressure sensor verification prototype capable of operating at elevated temperature.  With the intention of increasing knowledge of how high temperature influences piezoelectric dynamic pressure sensor readings, this thesis inherits and updates an existing pressure sensor verification device. A design of thermal management system for the device is presented together with a CFD model analysis for the cooling cycle, while the heating cycle and its control algorithm is studied experimentally. This thesis also focuses on sinusoidal pressure wave generation methods used in the existing verification device to achieve reliable signals at low frequencies. An experimental study to evaluate the signal quality is performed. The results propose a feasible prototype design for automated pressure sensor verification at elevated temperature. It provides insight on how the separate parts of the thermal management system could be implemented with a PID regulator. It is concluded that air heating, even with to some extent varying mass flow, can be controlled with a PID regulator. It is also concluded that stable sinusoidal pressure waves can be generated at as low as 1Hz with the gear wheel method used in the previous verification device.

Este trabalho explora o uso de fibras ópticas e comprimentos de onda nanométricos para a realização de medições químicas. A fibra óptica é empregada como parte integrante do sensor óptico, e não apenas como um guia de ondas. Este sensor apresenta-se como opção mais sensível, rápida e precisa aos métodos de análise e medições convencionais. Um sensor de concentração de corante que utiliza a técnica de absorção pelo campo evanescente de uma fibra óptica é analisado, construído e ensaiado. A região da fibra que constitui o sensor é formada por uma transição suave, obtida pelo método do tracionamento a quente. Este sensor opera em 633 nm para o corante violeta genciana com fibra monomodo. A teoria utilizada para calcular a atenuação da potência óptica transmitida pela fibra integrante do sensor é apresentada. A comparação teórica entre os desempenhos do sensor utilizando fibra monomodo e multimodo iluminadas por fontes de luz diferentes e com várias dimensões de estrangulamento é realizada. O procedimento de fabricação do sensor e o de medição da potência óptica para algumas concentrações do corante são descritos. Resultados experimentais da atenuação normalizada vs. concentração são apresentados e comparados aos valores teóricos. Os ensaios referentes a cada um dos estrangulamentos construídos foram realizados com 5 concentrações distintas do corante e com 4 repetições, no mínimo, para cada uma delas. / In this work optical fibers and nanometrical wavelenghts are used to perform chemical measurements. The optical fiber is part of the optical sensor, not only as a waveguide. This sensor emerges as a more sensible, precise and faster option when compared to conventional measurement and analysis methods. Active concentration sensor that uses the technique of the evanescent field absorption of an optical fiber is analised, built and essayed. The fiber portion, which constitutes the sensor, is a smooth transition taper, generated by the fiber stretching by heat. This sensor operates at 633 nm for the crystal violet dye with a singlemode optical fiber. The theory used to calculate the power attenuation of the sensor fiber guided light is presented. A theoretical performance confrontation of the sensor using singlemode, multimode, iluminated by different light sources and diff\'erent taper dimensions is realized. The sensor fabrication method is described as well as the light power measurement process for some dye concentrations. The experimental results for attenuation vs. dye concentration are presented and compared to the theoretical values. The essays, which refer to each one of the built tapers, have been realized using 5 different dye concentrations and, at least, 4 repetitions for each one.

Zugl.: Bremen, Univ., Diss., 2008

Zugl.: Braunschweig, Techn. Univ., Diss., 2009

Este trabalho explora o uso de fibras ópticas e comprimentos de onda nanométricos para a realização de medições químicas. A fibra óptica é empregada como parte integrante do sensor óptico, e não apenas como um guia de ondas. Este sensor apresenta-se como opção mais sensível, rápida e precisa aos métodos de análise e medições convencionais. Um sensor de concentração de corante que utiliza a técnica de absorção pelo campo evanescente de uma fibra óptica é analisado, construído e ensaiado. A região da fibra que constitui o sensor é formada por uma transição suave, obtida pelo método do tracionamento a quente. Este sensor opera em 633 nm para o corante violeta genciana com fibra monomodo. A teoria utilizada para calcular a atenuação da potência óptica transmitida pela fibra integrante do sensor é apresentada. A comparação teórica entre os desempenhos do sensor utilizando fibra monomodo e multimodo iluminadas por fontes de luz diferentes e com várias dimensões de estrangulamento é realizada. O procedimento de fabricação do sensor e o de medição da potência óptica para algumas concentrações do corante são descritos. Resultados experimentais da atenuação normalizada vs. concentração são apresentados e comparados aos valores teóricos. Os ensaios referentes a cada um dos estrangulamentos construídos foram realizados com 5 concentrações distintas do corante e com 4 repetições, no mínimo, para cada uma delas. / In this work optical fibers and nanometrical wavelenghts are used to perform chemical measurements. The optical fiber is part of the optical sensor, not only as a waveguide. This sensor emerges as a more sensible, precise and faster option when compared to conventional measurement and analysis methods. Active concentration sensor that uses the technique of the evanescent field absorption of an optical fiber is analised, built and essayed. The fiber portion, which constitutes the sensor, is a smooth transition taper, generated by the fiber stretching by heat. This sensor operates at 633 nm for the crystal violet dye with a singlemode optical fiber. The theory used to calculate the power attenuation of the sensor fiber guided light is presented. A theoretical performance confrontation of the sensor using singlemode, multimode, iluminated by different light sources and diff\'erent taper dimensions is realized. The sensor fabrication method is described as well as the light power measurement process for some dye concentrations. The experimental results for attenuation vs. dye concentration are presented and compared to the theoretical values. The essays, which refer to each one of the built tapers, have been realized using 5 different dye concentrations and, at least, 4 repetitions for each one.

No description available.

No description available.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Measuring the roll rate or roll position of a rolling airframe can be difficult. Some of the smaller missiles, which have roll rates in excess of 20 revolutions per second, have the least amount of room for a roll sensor such as a laser ring gyro or a quartz rate sensor. The large roll rates coupled with the rate sensor’s resolution can cause large errors in just a few seconds. The cost for these devices can be very high. The roll problem on rolling airframes has been solved by using two magnetic sensors that are 90 degrees out of phase from each other to measure the roll. The cost of the sensor is approximately $15 and is packaged in a 20-pin-surface-mount device. This paper addresses the design and the data processing algorithm to produce roll position. The sensor and algorithm were checked for accuracy on a CARCO table.