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 20 of 71 for “"Acoustics, Dynamics, and Controls"”.
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Quantification of an Ultrasound Test Apparatus and its Potential Use to Control Nuisance Species in Commercial Aquaculture Settings
As one step in the investigation of using acoustics to improve aquaculture production, work was pursued on the possible use of ultrasound to control the Bolbophorus trematode in commercial catfish ponds. The trematode population can be controlled by eliminating the host ram's horn snail via …
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Characterizing The Acoustic Properties Of The Jet Lab At The National Center For Physical Acoustics
… problems due to jet noise must be researched and addressed. Anechoic chambers were proposed as a testing facility for research in aerodynamic noise because of their supposed free-field characteristics. The international standard ISO 3745-1977 was introduced to determine whether the facilities …
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Reconstruction Resolution Of Coherent Point Sources With Helmholtz Equation Least Squares
… coefficients are solved for by least squares and used to reconstruct pressures at the source surface. By approximating the pressure radiation with expansion functions, field and surface pressures can be synthesized, resulting in the possibility of higher spatial resolution than previous …
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Effects of a Heated Turbulent Boundary Layer on Surface Pressure Fluctuations
… can give information about the velocity field and turbulence. This is of particular importance to the future of wind energy to predict the incoming velocity flow field of wind turbines so as to actively control them for peak operating efficiency and damage reduction. All of the environmental …
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Predicting the Acoustic Response of the Golf Club & Ball Impact Using Finite Elements and the Boundary Element Method
<p>An improved and repeatable method for meshing golf club heads using finite elements in TrueGrid® was developed. Using solid brick elements through the thickness of the club head instead of shell elements better represents the many thickness variations throughout each section of a club head. This …
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Optimization Of Wind Fence Enclosures For Infrasonic Wind Noise Reduction
… porous wind barrier enclosure has been built and tested to optimize wind noise reduction at infrasonic frequencies between 0.01-10 Hz in order to develop a technology that is simple, cost effective, and improves upon the limitations of pipe and porous hose arrays. The effects of varying the …
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Three Degree-of-Freedom Parallel Actuator Telescope Mount
… thesis contains the design, implementation, and testing of an original, small-scaled two degree-of-freedom telescope mount and a medium-scaled three degree-of-freedom telescope mount inspired by the six degree-of-freedom Stewart-Gough platform telescope mount. The end product is intended to …
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The Identification of Resonant Frequencies Emitted by Violins and Flat Top Guitars.
… by 2 types of stringed instruments, violins and guitars, in a definitive way that provides measured data for results. A resonance testing apparatus designed to support the instruments for testing, produce forced vibrations of precise period and amplitude to excite an instrument, and acquire …
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Dynamic Pressure Sensing for the Flight Test Data System
<p>This thesis describes the design, assembly, and test of the FTDS-K, a new device in the Boundary Layer Data System (BLDS) family of flight data acquisition systems. The FTDS-K provides high-frequency, high-gain data acquisition capability for up to two pressure sensors and an additional three …
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The Effect of Static Pressure on the Inertial Cavitation Threshold and Collapse Strength
… the acoustic pressure required to nucleate a gas and/or vapor bubble in a fluid, and to have that bubble undergo an inertial collapse, is termed the inertial cavitation threshold. The hydrostatic dependence of the inertial cavitation threshold was measured up to 30 MPa in ultrapure water using a …
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System Identification of a Cantilever Beam with Interferometer Measurement Using Adaptive Filters
… vibration analysis because its installation and mounting is invasive to dynamical systems. However, metrology systems that already utilize laser interferometry, such as profilometry in semiconductor manufacturing, may benefit from interferometer feedback for signal processing. This study …
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Development of a Rotordynamic Signal Processing MATLAB Interface and a Two-Disk Rotor Model
<p>Using MATLAB and a National Instruments data acquisition card, a signal processing program meant to monitor the behavior of rotordynamic systems in real-time was developed and tested. By using traditional analysis methods in this field of engineering, commonly desired data representations such …
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Helmholtz Equation Least Squares Based Near-Field Acoustic Holography With Laser
… presents the HELS based NAH with laser and use normal surface velocity as input in near-field acoustic holography. The conventional HELS based NAH uses acoustic pressure as input to reconstruct sound field quantities, while this modified HELS based NAH with laser utilizes the normal …
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Efficient modeling of sound source radiation in free-space and room environments
<p>Motivated by the need to develop efficient acoustics simulations for sources in different room environments, a modeling procedure has been proposed that consists of two steps in general: (1) the modeling of the free-space radiation of the source based on measurements in a anechoic environment, …
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High-Order Finite-Difference Schemes and Their Application to Computational Acoustics
… of high-order finite-difference schemes and their application to duct acoustics. Since acoustic waves are known to be non-dissipative and non-dispersive, high-order schemes are favored for their low dissipation and low dispersion relative to the low-order schemes. The primary obstacle to …
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Less-Than-Lethal Self Defense Device with an Acoustic Element
… project involves the conception, design, and creation of a less-than-lethal self defense device with an integrated sound board to control the acoustic element. Theoretically, this device is capable of deterring potential threats without causing any serious harm or any long-term damage. …
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