Global ETD Search
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 16 of 16 for “"laser vibrometry"”.
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Vehicle Engine Classification Using of Laser Vibrometry Feature Extraction
<p>Used as a non-invasive and remote sensor, the laser Doppler vibrometer (LDV) has been used in many different applications, such as inspection of aircrafts, bridge and structure and remote voice acquisition. However, using LDV as a vehicle surveillance device has not been feasible due to the lack …
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Vibrations of high-speed dental handpieces measured using laser vibrometry
… loaded conditions using a non-contact Scanning Laser Vibrometer (SLV). Methods: Five turbines (two KaVo, three W&H) and two speed-increasing handpieces (one KaVo and one W&H) were investigated using a Polytec SLV (PSV-300). Handpieces were operated under various conditions which included …
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Remote nondestructive evaluation of composite-steel interface by acoustic laser vibrometry
… form of nondestructive testing (NDT). Acoustic laser vibrometry is a relatively new method of NDT that shows a lot of promise in analysis of this interface. In this approach, an airborne acoustic wave is utilized to excite the location of the damage underneath the FRP sheets/plates and the …
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Detection of defects in FRP-reinforced concrete with the acoustic-laser vibrometry method
… A novel approach called the acoustic-laser vibrometry method which is capable of remote assessment of damage in FRP-reinforced concrete, is investigated in this thesis. It exploits the fact that areas where the FRP has debonded from concrete will vibrate excessively compared to intact …
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Static Misalignment Effects is a Self-Tracking Laser Vibrometry System for Rotating Bladed Disks
The application of laser Doppler vibrometry to high speed rotating structures has been hampered by technical limitations. Whereas full-field three-dimensional velocity measurements can be made on stationary structures, the capability on rotating structures is limited to low speed, one-dimensional, …
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The assessment of ultrasonic instruments in dentistry
… have previously been difficult to analyse. Laser vibrometry is a non-invasive technique for measuring the vibration characteristics of oscillating objects. Aim: The aim of this research thesis was to utilise scanning laser vibrometry to assess a range of dental ultrasonic systems under …
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Do Butterflies Use "Hearing Aids"?Investigating the Structure and Function of Inflated Wing Veins in Nymphalidae
… and evolution of these inflated veins. A laser vibrometry study showed that ears in the common wood nymph, Cercyonis pegala, are tuned to sounds between 1-5 kHz and the inflated subcostal vein enhances sensitivity to these sounds. A comparative study showed that all species with inflated …
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Physics and Algorithms in Time of Flight Based Computational Imaging
… advanced electronics hardware like femtosecond lasers, and Single Photon Avalanche Photodiode(SPAD) detectors for the automatic calibration project and software tools meant for machine learning in Python. For optical ultrasound measurement, I will use relatively simple hardware like solid state …
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Misalignment Effects of the Self-Tracking Laser Doppler Vibrometer
… further describes aspects of a self-tracking laser vibrometry system that can be used to measure the vibrations of rotating structures. This method, if setup correctly, has the capability to overcome many of the limitations listed above. A study of all misalignment effects is presented in this …
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Tuning of the middle ear in túngara frogs ( Engystomops pustulosus)
… sound reception pathways described above. Using laser vibrometry, I evaluated the vibration response of the eardrum and body wall to airborne sound. The results revealed a clear mismatch between the tuning of both middle ear and lungs, and that of the brain, with the eardrums and lungs tuned to …
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Guided Waves Technique for Measurement of Contained Stress in Uniform Slender Elastic Bodies
… load, is proposed in this thesis. Scanned laser vibrometry measurements of vibration fields at a prescribed frequency, followed by a comparison with guided wave theory, allow extraction of the wavenumbers associated with all the propagating and evanescent modes in the body. The wavenumber …
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Examination of the application and limitations of structural mode extraction via force apportionment
… examining the structural response as measured by laser vibrometry. First, the structure is investigated using impact-test-based modal extraction methods. Approximate mode shapes are determined by examining the phase resonance indicator function for the resonance responses at a number of reference …
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Biomechanical and neurophysiological investigation of insect tympanal organs
… of various species and orders of insect using laser Doppler vibrometry. The results were then compared between species, including the different structures and also the membrane mechanics. This chapter results highlights the different structures and also the range of frequencies that each …
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Methods for Validation of a Turbomachinery Rotor Blade Tip Timing System
… were validated to within 4% using scanning laser vibrometry. The simulation was repeated at speed to produce a Campbell Diagram to highlight synchronous excitation crossings.
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Theoretical and Experimental Studies of Manipulation of Elastic Waves in Helix Metamaterials
… Wide low-frequency bandgap; Controllable design; Laser vibration measurement; Strong vibration attenuation; Carrera Unified Formulation Abstract Elastic metamaterials exhibit mechanical properties unattainable in natural materials and demonstrate vast potential in vibration and noise reduction, …