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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 40 for “"fiber sensor"”.
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An optic fiber sensor for partial discharge acoustic detection
… are consistent with theoretical expectations. Fiber optic-based sensors have been shown to be attractive devices for PD detection because of a number of inherent advantages including small size, high sensitivity, electrical nonconductivity, and immunity to electromagnetic interference (EMI). A …
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Axial offset effects upon optical fiber sensor and splice performance
A kind of intensity modulated fiber sensor utilizing axial offset parameter is proposed. The theoretical analysis and experimental characteristics of this sensor are described. All the theoretical results derived in this thesis are based on assuming a uniform power distribution in the fibers. An …
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Fabrication of intensity-based Long-Period-Gratings fiber sensor with CO2 Laser
… for producing long period grating (LPG) fiber sensors with point-by-point irradiation under a CO2 laser beam. The type of fiber sensor under examination is desirable to be highly sensitive to the variation of the thickness and refractive index of a thin film deposited on the LPGs, making …
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Imbedded optical fiber sensor of differential strain and temperature in graphite/epoxy composites
A novel optical fiber sensor for the measurement of strain and temperature in graphite-epoxy composite materials using differential interferometry is described. The sensor uses two single-mode optical fiber waveguides imbedded within the composite during prepreg ply lay-up. Strain and temperature …
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Parameter identification of a flexible beam using a modal domain optical fiber sensor
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 …
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Quasi-Distributed Intrinsic Fabry-Perot Interferometric Fiber Sensor for Temperature and Strain Sensing
… quasi-distributed temperature and strain sensors that can reliably work under harsh environment or in extended structures. There are two main drives for distributed fiber sensor research. The first is to lower cost-per-sensor so that the fiber sensors may become price-competitive against …
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Real-Time Signal Processing and Hardware Development for a Wavelength Modulated Optical Fiber Sensor System
The use of optical fiber sensors is increasing widely in civil, industrial, and military applications mainly due to their, (a) miniature size, (b) high sensitivity, (c) immunity from electro-magnetic interference, (d) resistance to harsh environments, (e) remote signal processing ability, and, (f) …
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Intrinsic Fabry-Perot Interferometric Fiber Sensor Based on Ultra-Short Bragg Gratings for Quasi-Distributed Strain and Temperature Measurements
… this task using conventional electrical strain sensors. Fiber optic sensors provide an excellent opportunity to fulfill this need due to their capability to multiplex many sensors along a single fiber cable. Numerous research studies have been conducted in past decades to increase the number of …
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Photoinduced, refractive-index gratings in germanium-doped two-mode, elliptical-core optical fibers
… of germanium-doped, two-mode, elliptical-core fibers are found to affect the differential phase modulation between the co-propagating LP₀₁ and LP₁₁ even modes. The modal beat length of a two-mode fiber grating is found to vary inversely with strain induced to the fiber and leads to a new type …
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Loss phenomena in perturbed single-mode optical fibers: investigation and applications
Losses induced in a single-mode fiber due to periodic spatial deformations along the fiber axis have been investigated spectrally. Deformation losses in several single-mode fibers were found to be strongly wavelength dependent. This wavelength dependence was characterized by narrow attenuation …
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Optical Path Length Multiplexing of Optical Fiber Sensors
Optical fiber sensor multiplexing reduces cost per sensor by designing a system that minimizes the expensive system components (sources, spectrometers, etc.) needed for a set number of sensors. The market for multiplexed optical sensors is growing as fiberoptic sensors are finding application in …
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High temperature tolerant optical fiber inline microsensors by laser fabrication
"Fiber sensors are particularly attractive for harsh environment defined by high temperature, high pressure, corrosive/erosive, and strong electromagnetic interference, where conventional electronic sensors do not have a chance to survive. However, the key issue has been the robustness of the …
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Sapphire fiber in optical sensors
The physical and optical properties of sapphire fiber has been investigated in an effort to create a high temperature optical fiber sensor. Sapphire fiber demonstrates high optical attenuation. This attenuation is very sensitive to injection conditions, and roughly proportional to the cube of the …
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Simultaneous measurement of strain and temperature using liquid core optical fiber sensors
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. …
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Optical fiber sensors for advanced civil structures
… is to develop, analyze, and implement optical fiber-based sensors for the nondestructive quantitative evaluation of advanced civil structures. Based on a comparative evaluation of optical fiber sensors that may be used to obtain quantitative information related to physical perturbations in the …
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High resolution optical time domain methods for measuring strain
… applied to measuring strain in an optical fiber are discussed. The use of this optical time-domain fiber sensor for measuring quasi-distributed strain along a cantilevered beam is experimentally demonstrated. This is accomplished by segmenting the sensor with air-gap sites, allowing …
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Production of controlled networks and morphologies in toughened thermosetting resins using real-time, in-situ cure monitoring
… a need for the development of in-situ real-time sensors to follow these changes. Once these sensors are developed, they can be used to preferentially select networks and/or morphologies by feedback-controlled "intelligent" processing. A practical, durable, inexpensive Fourier Transform …
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Extrinsic Fabry-Perot interferometer for surface acoustic wave measurement
A surface acoustic wave sensor based on an extrinsic Fabry-Perot interferometer is described. A single-mode fiber, used as the input/output fiber, and a multimode fiber, used mainly as a reflector, form an air-gap that acts as a low-finesse Fabry-Perot cavity. The Fresnel reference reflection from …
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Chemical sensing applications of fiber optics
… of this research is the implementation of a fiber optic sensor to measure refractive indices of unknown solutions. The surface plasmon sensor, interrogated with white light resulted in attenuations of light at different wavelengths when solutions of different refractive indices were …
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The properties of single crystal sapphire fibers and the polarimetric optical sensor for high temperature measurements
… properties of single crystal sapphire fibers are investigated and a polarimetric optical sensor for high temperature measurements is designed. The polarization-maintaining properties of single crystal sapphire fibers are investigated experimentally for different modal power …
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