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.
Results
Showing 1 to 20 of 72 for “"acoustic energy"”.
-
Acoustic energy harvesting with emphasis on low frequencies
… novel findings and results in the field of acoustic energy harvesting with emphasis on low frequencies. At the beginning of this work, ambient acoustic power density is estimated and a comparison between the potential of sound and that of other ambient energy sources exploited for energy …
-
Broadband acoustic energy harvesting via synthesized electrical loading
… technology for self-powered sensor nodes is acoustic energy harvesting (AEH): deriving energy from ambient sound. Current AEH designs are typically based on resonant structures, yielding narrowband energy harvesting and therefore low efficiencies from broadband noise sources. They also …
-
Analysis and Comparison of Three Acoustic Energy Density Probes
… sound pressure is directly related to potential energy density. Consequently, the measurement of sound pressure alone does not inherently provide insight into the total energy density of the sound field. Specifically, no information about the kinetic energy density of the sound field is available …
-
Theoretical Parametric Study of Through-Wall Acoustic Energy Transfer Systems
… advances require novel solutions for contactless energy transfer. Many engineering applications require unique approaches to power electrical components without using physical wires. In the past decade, awareness of the need to wirelessly power electrical components spawned many forays into the …
-
Active Minimization of Acoustic Energy Density in a Mock Tractor Cab
… algorithm, modified for the minimization of acoustic energy density (ED), rather than the more traditional minimization of squared acoustic pressure (SP). Three loudspeakers produced control signals within a mock cabin composed of a steel frame with plywood sides and a Plexiglas® front. An …
-
Scattering of acoustic energy from rough deep ocean seafloor: A numerical modeling approach
… seafloor results in complex reverberation as acoustic energy incident from the overlaying water column interacts and scatters from it. To gain a deeper understanding of the mechanisms causing the reverberation in sonar and seafloor scattering experiments, we have developed numerical simulation …
-
Active Minimization of Acoustic Energy Density to Attenuate Radiated Noise from a Diesel Generator
… LMS adaptive algorithm, which minimizes energy density (ED). Both feedforward and feedback control approaches were investigated. The noise spectrum produced by the diesel generator enclosure includes tonal and broadband components. The target range for control was from 0 to 300 Hz. Tonal …
-
A comparison of short-circuited streaming potentials in Westerly granite from changes in the rock's volume, shape, saturation, and fracture under unconfined uniaxial compression
… there is a strong suggestion that the amount of acoustic energy released when the sample fractures is proportionately related to the amount of charge that moves into or out of the sample, the net charge, over the period of the experiment. Increasing the concentration of the saturating solution …
-
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 …
-
Antipodal receptions in global acoustics
Global Acoustic Propagation is a recently developed scientific discipline within the study of long range underwater acoustic propagation. Acoustic propagation over extremely long ranges involves a combination of effects from earth curvature and the global distribution of oceanographic and …
-
Low loss film bulk acoustic resonator in liquid environments
… AT AUTHOR'S REQUEST.] A film bulk acoustic resonator (FBAR) is an acoustic resonator mass sensor using the resonance of longitudinal or shears acoustic waves. There is a significant Q factor loss in liquid medium due to acoustic energy loss. This drastically affects the minimum …
-
Ocean bottom seismic scattering
… significant affect on the propagation of seismo/acoustic energy through the crust, especially in the immediate vicinity of the seafloor. This thesis deals with the problem of scattering of seismo/acoustic energy from a number of forms of lateral heterogeneity in the upper oceanic crust. A common …
-
Development of a Multiple Microphone Probe Calibrator
… done in conjunction with the development of an acoustic energy density probe, which was used to validate the calibrator. The probe uses multiple microphones to acquire the data needed to compute the acoustic energy density. The probe microphones are 0.006 m diameter electret microphones which …
-
A Hierarchical Noise Control System Using Adaptable Tuned Vibration Absorbers
… structure in such a way as to reduce radiated acoustic energy. ATVA's are single-degree-of-freedom resonant devices that can change their resonant frequency and damping over a range. This ATVA noise control system is targeted at applications with tonal disturbances such as propeller aircraft. …
-
Sound Absorption and Sound Power Measurements in Reverberation Chambers Using Energy Density Methods
… to obtain suitable measurements. The total acoustic energy density provides greater spatial uniformity than squared pressure, which requires fewer source-receiver positions to produce similar or better accuracy in measurement results. This paper explores the possibility of using energy …
-
Adaptive Collocated Feedback for Noise Absorption in Acoustic Enclosures
… on adaptive feedback control for low frequency acoustic energy absorption in acoustic enclosures. The specific application chosen for this work is the reduction of high interior sound pressure levels (SPL) experienced during launch within launch vehicle payload fairings. Two acoustic enclosures …
-
Field Use Of An Acoustic Surrogate System To Monitor Gravel Bed Load Flux
… Since studies have shown a relationship between acoustic energy and particle impacts, the field of acoustics has shown potential in providing real-time measurements. These systems employ acoustic sensors such as geophones, sonar, and hydrophones. The research presented here utilizes a passive …
-
Multi-functional Holographic Acoustic Lenses for Modulating Low- to High-Intensity Focused Ultrasound
… an essential role in clinical and contactless acoustic energy transfer applications. These applications have critical criteria for the acoustic pressure level, the creation of complex pressure patterns, spatial management of the complicated acoustic field, and the degree of nonlinear waveform …
-
The Effect of Static Pressure on the Inertial Cavitation Threshold and Collapse Strength
The amplitude of 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 …
-
NORMAL MODE SPECTRA OF SOUND WAVES IN VISCOUS SOLID AND FLUID MEDIA WITH PARTICULAR APPLICATIONS TO SHALLOW WATER ACOUSTICS
… condition utilizing the definition of specific acoustic impedance. A depth-dependent sound speed is treated in the ideal liquid layer.</p><p>In order to determine the most convenient mathematical representation for this shallow water model an investigation of the normal mode spectra of sound …
Page 1 of 4