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 57 for “"Acoustic response"”.
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Acoustic Response Validation of a Finite Cylindrical Shell with Multiple Loading Conditions
… capabilities of these models by examining the acoustic response of a finite length cylinder with flat plate endcaps to multiple types of distributed loading conditions. Starting with the Donnell equations of motion for thin cylinders and the classical plate theory equations of motion for the …
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Structural & Internal Acoustic Response of Cylinders with Applications to Rocket Payload Fairings
… causes a significant increase in the internal acoustic environment, causing a severe threat to the payload. Using piezoelectric actuators to control the fairing vibration and the internal acoustic environment has been proposed. The control authority of these actuators for this problem has not …
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Effects of duct source and termination impedance on the acoustic response characteristics of duct elements
… the effects of termination of an air duct on the acoustic response characteristics of the elements in the duct system. The end reflections due to the mis-match of the acoustic impedance at the termination affect the acoustic characteristics of the duct elements; The ducts of the duct system, …
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Effect of grazing flow on structural-acoustic response of an elastic plate with sound in a duct
… accurate prediction of the coupled structural-acoustic response of thin panels subjected to sound waves are key elements of this design process. Due to the cost of in-flight testing, the experimental assessment of the structural-acoustic response of skin panels is usually conducted in …
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Predicting the Acoustic Response of the Golf Club & Ball Impact Using Finite Elements and the Boundary Element Method
… procedure was also developed to predict the acoustic pressure at a designated point in an acoustic medium of a golf club and ball impact using the BEM and Rayleigh methods in LS-DYNA®. The simulation time and computing power required for the impact are modest, while the acoustic simulation …
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A comparison of analytical models and experimental results for the acoustic response in a non-rigid-wall enclosure
… need for an accurate modeling approach for the acoustic response in a non-rigid-wall enclosure. The acoustic response in any enclosure is determined by the boundary conditions at the interior surface of the enclosure walls, and the types of sources present. The analyses presented in this thesis …
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Experimental Characterization and Analysis of Simple Residential Structures Subjected to Simulated Sonic Booms
… to understand and accurately reproduce the acoustic response of a sonic boom is important for psychoacoustic classification of their tolerability within residences. This thesis presents and interprets results of the propagation and transmission of simulated sonic booms incident on …
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Vibro-acoustic optimization of panel with curvilinear stiffeners
… stiffened panels with predefined structural and acoustic response is the focus of this dissertation. Researchers have dealt with sizing optimization of panels with straight/curvilinear stiffeners for many years and it has been proven that in some cases the mass of a panel with curvilinear …
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Low Frequency Finite Element Modeling of Passive Noise Attenuation in Ear Defenders
… responsible for the low frequency (0 – 300 Hz) acoustic response inside the earmuffs. A large volume earcup is used with the undercut seal for the study. The significance of this research is the use of finite element methods in the area of hearing protection design. The objectives of this …
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Turbulence and Sound Generated by a Rotor Operating Near a Wall
Acoustic and aerodynamic measurements have been carried out on a rotor operating in a planar turbulent boundary layer near a wall for a variety of thrust conditions and yaw angles with respect to the inflow. At the highest thrust condition a strong flow reversal in the wall-rotor tip gap was …
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Acoustic Behavior Of Soil Reinforced With Grass Roots
… to the mobilization of roots' tensile strength. Acoustics can be used to monitor internal changes of soil by interacting with soil particles and interstitial fluids. Compressional wave, or p-wave, velocity can be used to predict changes in effective stress and bulk density which can be related to …
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The active minimisation of harmonic enclosed sound fields, with particular application to propeller induced cabin noise
This work considers the use of secondary acoustic sources for the reduction of noise levels in harmonically excited enclosed sound fields. This possibility is studied initially through the use of an analytical model of a single frequency 'two-dimensional' rectangular, enclosed sound field of low …
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Structural acoustic analysis of shape memory alloy hybrid composite panels
… the Rayleigh-Ritz method and finite panel acoustic radiation theory to investigate the use of SMA hybrid composite materials for adaptive structural acoustic control by active structural tuning. Analytical models are formulated considering classical laminated plate theory (CLPT) and …
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Linear Modeling and Analysis of Thermoacoustic Instabilities in a Gas Turbine Combustor
… transfer function depicting the frequency response of the thermoacoustic system. These blocks include the system acoustic response to unsteady heat release forcing, the air-side coupling of acoustic particle velocity to inlet fuel mass fraction, transport delays present in the mixing nozzle …
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Mass transfer, creep and stress development during the drying of red oak
… is greatest early in drying. As an adjunct, acoustic response tests were performed on green samples stressed perpendicular to grain in flexure under third point loading conditions. The evidence indicates that the onset of surface failure can be predicted prior to the appearance of macroscopic …
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THE EFFECT OF TROPICAL CYCLONE PASSAGE ON UNDERSEA ACOUSTIC PARAMETERS IN THE EAST CHINA SEA
… impact of tropical cyclone passage on undersea acoustic parameters in the East China Sea using 222 historical tropical cyclone tracks and seven acoustic parameters from 1979 to 2010 (i.e., the global warming period). Data from the Fleet Numerical Meteorology and Oceanography Center’s Climate …
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Systematic Prediction and Parametric Characterization of Thermo-Acoustic Instabilities in Premixed Gas Turbine Combustors
… coincident prediction and observation of thermo-acoustic instabilities in a turbulent, swirl-stabilized research combustor using a stability model constructed from validated reduced-order component models. The component models included the acoustic response to flame heat release rate at various …
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Development of a Model for Predicting the Transmission of Sonic Booms into Buildings at Low Frequency
… loading, structure vibration, and interior acoustic response. Past investigations on this problem have tackled all these aspects but were limited to simple structures and often did not account for the coupled fluid-structure interaction. A more comprehensive work that includes all the …
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The role of system dynamics on the behavior of elastomeric friction
… measure the friction torque and the system and acoustic response of the sliding system. Several materials including a fluorocarbon elastomer, a polydimethylsiloxane, and a natural rubber were tested. Three friction regimes were observed which were stick-slip oscillations, quasi-harmonic …
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