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 85 for “"Sound-waves"”.
-
Behavior of low-frequency sound waves in porous media
This is a study of the relationship between the measured acoustic parameters and the measured physical parameters of porous media. Materials studied include crushed limestone, stream-formed pea gravel, large and small sifted pea gravels, and glass spheres. A standing wave curve fitting algorithm …
-
Sound Waves and Turbulence in Two-dimensional Bose Gases
… We begin with the studies of the propagation of sound. For temperatures below the BKT critical temperature, we observe first and second sound, as predicted by the hydrodynamic two-fluid model. From the two temperature-dependent speeds of sound and the established thermodynamic properties of the …
-
The scattering of sound waves in two-dimensional ducts with discontinuities in height and material property
Eigen-mode matching techniques offer a versatile approach for solving acoustic scattering problems in ducts. However, until recently, these techniques have been restricted to problems in which the boundary conditions contain at most one derivative, that is, Neumann, Dirichlet or Robin's conditions. …
-
NORMAL MODE SPECTRA OF SOUND WAVES IN VISCOUS SOLID AND FLUID MEDIA WITH PARTICULAR APPLICATIONS TO SHALLOW WATER ACOUSTICS
<p>Sound propagation in shallow water is modelled using the Green's function formalism and normal mode techniques. The water layer is bounded above by a pressure-released condition and below by a halfspace of viscoelastic solid media. Nine different marine sediments are investigated by …
-
Less-Than-Lethal Self Defense Device with an Acoustic Element
… 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. When starting this project, I was very focused on sonic warfare, and how to …
-
The velocity of sound in solid krypton
… from polycrystalline specimens for longitudinal sound waves from 52 to 115 K and transverse sound waves from 95 to 115 K, and from a single crystal for longitudinal sound waves travelling in a nearly (110) direction from 94-114 K. Extrapolations to 0 K of polycrystalline velocities are consistent …
-
Ultrasonic Continuous Wave Spirometer
… and sum of the transit times for two continuous sound waves travelling in opposite directions along the air path. The information about the transit times is contained in the phase differencces of the two sound waves across the path. A phase-locked loop is used to keep the differences across the …
-
Effects of duct source and termination impedance on the acoustic response characteristics of duct elements
… With this type of termination much of the sound energy in lower frequencies is reflected. This sets up standing sound waves inside the duct. The analytical methods to calculate the insertion-loss, noise reduction consider single reflection only inside the duct. Because of that, the …
-
An ultrasonic study of hydroxyl ion in single crystals of rubidium chloride
… o~ absorption and velocity changes of sound waves on single crystals of RbCl containing OH ions were made as a function of polarization, frequency, concentration and temperature from 0.6 K to 24 K. A rise in absorption of the low frequency (10 to 70 MHz) Cmode sound waves has been …
-
Application of ray acoustics to the propagation of sound in ducts containing sheared flows
… acoustics has been applied to the propagation of sound waves in a homogeneous moving medium with sheared flow bounded by the hard walls of a duct. Differential equations describing the ray trajectories and spreading losses along each ray were developed and solved numerically for a range of …
-
Sound Propagation via Narrow Beam Audio Projection
… ago. It consists in the generation of secondary sound waves by the propagation of two collimated primary ultrasonic waves at a close frequency. The sound wave generated corresponds to the difference of the frequencies propagated and its existence is independent from the ultrasonic waves, but it …
-
Backscatter and Attenuation Characterization of Ventricular Myocardium
… hearts with the goal of studying the physics of sound waves incident upon anisotropic and inhomogeneous materials. Ultrasound has been used as a clinical tool to assess heart structure and function for several decades. The clinical usefulness of this noninvasive approach has grown with our …
-
Anwendung des Lattice-Boltzmann-Verfahrens zur Berechnung strömungsakustischer Probleme
… the first part of this study the description of sound wave propagation by common variants of the Lattice-Boltzmann-model is examined by calculation of phase velocity and effective viscosity for sound waves. Schemes with nine velocities in two dimensions and nineteen velocities in three dimensions …
-
Prediction of low-frequency sound-pressure fields in fitted rooms for active noise control
… which relies on destructive interference of sound waves to reduce noise levels. However, this depends on phase, and how it is affected when sound waves encounter diffracting obstacles. In addition, the geometrical configuration of the active-control system must be optimized, which can be done …
-
The applicability and accuracy of computer modeling in regards to acoustical scattering by a complex geometry
… suffice. Instead, the distribution of reflected sound waves over a hemispherical shell will be examined.
-
Acf7 is a Hair-Bundle Antecedent, Positioned to Integrate Cuticular Plate Actin and Somatic Tubulin
… inner ear converts mechanical stimuli, such as sound waves, into electrical impulses which are then sent to and interpreted by the brain. Proper organization of the actin and microtubule cytoskeletons is important for establishing the distinct morphology of the hair cell, which is crucial for …
-
Measuring Acoustic Attenuation of Polymer Materials Using Drop Ball Test
… effect of a material in reducing the strength of sound waves traveling through it is called acoustic attenuation. In the past, attenuation has mostly been evaluated in the MHz frequency range, using a pulse generator and transmitting transducer as the wave source. However, most real acoustic …
-
Nonlinear Acoustics and an Inverse Scattering Problem
… on the ground, in terms of the form of the sound waves once they reach the ground. The work on landmine detection originated from a Knowledge Transfer Partner- ship between the University of East Anglia (UEA) and Cobham Technical Services (CTS) organised through the Knowledge Transfer …
Page 1 of 5