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 10 of 10 for “"acoustic cavity"”.
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A Coupled Tire Structure-Acoustic Cavity Model
… shown that the vibration induced by the tire air cavity resonance is transmitted into the vehicle cabin and may be responsible for significant interior noise. The tire acoustic cavity is excited by the road surface through the contact patch on the rotating tire. The effect of the cavity resonance …
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OPTIMIZATION OF A PIEZOELECTRIC ACOUSTICAL COMPRESSOR
… generate finite amplitude standing waves in an acoustic cavity with rigid walls. The model includes the effects of viscous and thermal damping of the fluid at the boundary of the cavity, and material damping in the piezoelectric actuator. Two types of piezoelectric actuators are considered, a …
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Optimal placement of sensor and actuator for sound-structure interaction system
… engineering applications. An experimental acoustic cavity with five walls of timber and a thin aluminium sheet fixed tightly on the cavity mouth is chosen in this thesis as a good representation of general sound-structure interaction systems. The sheet is intentionally so fixed that it does …
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A study of active control techniques for noise reduction in an aircraft fuselage model
… Noise reductions for harmonic excitation at acoustic cavity resonance are shown to be in excess of 20 dB throughout most of the cavity whether synchrophasing or active vibration control is used. Off-resonance reductions are substantially less due to increased modal density requiring a larger …
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The influence of structural-acoustic coupling on the dynamic behaviour of a one-dimensional vibro-acoustic system
… of this thesis is to investigate the structural-acoustic coupling effects on the dynamic behaviour of a vibro-acoustic system under passive/active control. The simplest model of a vibro-acoustic system one can consider is a one-dimensional acoustic cavity driven by a single-degree-of-freedom …
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Heterogeneous (HG) Blankets for Improved Aircraft Interior Noise Reduction
… of a single-bay double panel system (DPS) with, acoustic cavity, HG blanket and radiated field, later a multi-bay DPS with frames, stringers, mounts, and four HG blankets, was developed and experimentally validated using impedance and mobility methods (IMM). A novel impedance matrix formulation …
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Control of sound transmission into payload fairings using distributed vibration absorbers and Helmholtz resonators
… resonators (HR). A fully coupled structural-acoustic model of a composite cylinder excited by an external plane wave is developed as a first approximation of the system. A modal expansion method is used to describe the behavior of the cylindrical shell and the acoustic cavity; the noise …
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Optimisation of chaotic thermoacoustics
In an acoustic cavity with a heat source, such as a flame in a gas turbine, the thermal energy of the heat source can be converted into acoustic energy, which may generate loud oscillations. If uncontrolled, these acoustic oscillations, also known as thermoacoustic instabilities, can cause …
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Output-Only Experimental Modal Testing of Large Residential Structures and Acoustic Cavities Using Sonic Booms
… also demonstrates the successful use of NExT on acoustic systems for the first time. Three configurations of the interconnected cavities enclosed by the two room structure are considered to study physical phenomena. Both interior pressure response to random, stationary inputs and the sonic boom …