PARAMETER ANALYSIS IN ACOUSTIC CONTRAST CONTROL DESIGN SCHEME FOR A LOUDSPEAKER ARRAY

2012 ◽  
Vol 20 (04) ◽  
pp. 1250016 ◽  
Author(s):  
BO-HSIEN WU ◽  
GEE-PINN TOO
Keyword(s):  
Energy Density ◽  
Potential Energy ◽  
Sound Field ◽  
Parameter Analysis ◽  
Emission Frequency ◽  
Dark Zone ◽  
Parameters Analysis ◽  
Simulation Parameters ◽  
Source Array ◽  
Audio System

The concept of acoustic contrast control divides a sound field into bright zone and dark zone. A source array is used to increase acoustic potential energy density in the bright zone and to decrease acoustic potential energy density in the dark zone by controlling amplitude and phase of each source. In the present study, a personal audio system which is based on acoustic contrast control is designed. The purpose is to focus the acoustic potential energy around the region of listener. The optimal configuration for sound field is controlled by using a loudspeaker array. Parameters analysis is considered in simulation. Parameters, such as: the quantity of loudspeakers, the spacing of loudspeakers, the length of array, and the emission frequency are discussed. Finally, two experiments are conducted in a semi-anechoic room and a reverberation room, respectively. The results are shown to verify this approach in the present study.

scholarly journals Spatially Broad Observations of Internal Waves in the Upper Ocean at the Hawaiian Ridge

2006 ◽  
Vol 36 (6) ◽  
pp. 1085-1103 ◽  
Author(s):  
Joseph P. Martin ◽  
Daniel L. Rudnick ◽  
Robert Pinkel
Keyword(s):  
Numerical Model ◽  
Energy Density ◽  
Potential Energy ◽  
Internal Waves ◽  
Upper Ocean ◽  
Mean Square ◽  
The South ◽  
South Side ◽  
Topographic Slope ◽  
Hawaiian Ridge

Abstract The density and current structure at the Hawaiian Ridge was observed using SeaSoar and Doppler sonar during a survey extending from Oahu to Brooks Banks. Across- and along-ridge changes in internal wave statistics in the upper ocean within 200 km of the ridge are investigated. Internal waves with trough-to-crest amplitude as large as 60 m and horizontal wavelength of about 50 km are observed repeatedly in across-ridge sections of potential density. Within 150 km of the ridge, kinetic and potential energy density exceed open-ocean values with maxima about 10 times Garrett–Munk levels. In the Kauai Channel (KC), the kinetic energy density is largest along an M2 internal tide ray. The ray originates at the northern edge of the ridge peak at a large across-ridge change in topographic slope and terminates at the ocean surface about 30–40 km south of the ridge peak. Kinetic and potential energy density are larger on the south side of the ridge at KC, the side with larger topographic slope. Energy density is also larger on the south side of the ridge at KC in numerical model results and on the side of steeper topographic slope in analytical model results. Along the ridge, the largest observed values of mean-square shear and mean-square slope of isopycnal depth are collocated with the largest energy density in numerical model results. Mean-square shear and mean-square slope increase with decreasing bottom depth and with increasing M2 barotropic tidal forcing.

A constitutive model for an internally balanced compressible elastic material

2016 ◽  
Vol 22 (3) ◽  
pp. 372-400 ◽  
Author(s):  
Ashraf Hadoush ◽  
Hasan Demirkoparan ◽  
Thomas J Pence
Keyword(s):  
Energy Density ◽  
Potential Energy ◽  
Constitutive Models ◽  
Field Equations ◽  
Multiplicative Decomposition ◽  
Finite Strain Plasticity ◽  
Decomposition Formula ◽  
New Feature ◽  
Internal Balance ◽  
Traction Boundary Conditions

Many large deformation constitutive models for the mechanical behavior of solid materials make use of the multiplicative decomposition [Formula: see text] as, for example, used by Kröner in the context of finite-strain plasticity. Then [Formula: see text] describes the elastic effect by letting the potential energy of the deformation depend upon [Formula: see text]. In this paper we allow the potential energy to depend upon both portions of the multiplicative decomposition. As in hyperelasticity, energy minimization with respect to displacement gives equilibrium field equations and traction boundary conditions. The new feature, minimization with respect to the decomposition itself, generates an additional mathematical requirement that is interpreted here in terms of a principle of internal mechanical balance. We specifically consider a Blatz–Ko-type solid suitably generalized to incorporate the notion of internal balance. Conventional results of hyperelasticity are retrieved for certain limiting forms of the energy density, whereas the general form of the energy density gives rise to an overall softening response, as is demonstrated in the context of pure pressure and uniaxial loading.

On potential energy density in an incompressible, stratified fluid

1981 ◽  
Vol 107 (-1) ◽  
pp. 221 ◽  
Author(s):  
Dennis Holliday ◽  
Michael E. Mcintyre
Keyword(s):  
Energy Density ◽  
Potential Energy ◽  
Stratified Fluid

Standing Internal Tides in the Tasman Sea Observed by Gliders

2015 ◽  
Vol 45 (11) ◽  
pp. 2715-2737 ◽  
Author(s):  
T. M. Shaun Johnston ◽  
Daniel L. Rudnick ◽  
Samuel M. Kelly
Keyword(s):  
Energy Density ◽  
Potential Energy ◽  
Specular Reflection ◽  
Internal Tide ◽  
Internal Tides ◽  
Kinetic Energy Density ◽  
Underwater Gliders ◽  
Tasman Sea ◽  
Almost All ◽  
Realistic Topography

AbstractLow-mode internal tides are generated at tall submarine ridges, propagate across the open ocean with little attenuation, and reach distant continental slopes. A semidiurnal internal tide beam, identified in previous altimetric observations and modeling, emanates from the Macquarie Ridge, crosses the Tasman Sea, and impinges on the Tasmanian slope. Spatial surveys covering within 150 km of the slope by two autonomous underwater gliders with maximum profile depths of 500 and 1000 m show the steepest slope near 43°S reflects almost all of the incident energy flux to form a standing wave. Starting from the slope and moving offshore by one wavelength (~150 km), potential energy density displays an antinode–node–antinode–node structure, while kinetic energy density shows the opposite.Mission-mean mode-1 incident and reflected flux magnitudes are distinguished by treating each glider’s survey as an internal wave antenna for measuring amplitude, wavelength, and direction. Incident fluxes are 1.4 and 2.3 kW m−1 from the two missions, while reflected fluxes are 1.2 and 1.8 kW m−1. From one glider surveying the region of highest energy at the steepest slope, the reflectivity estimates are 0.8 and 1, if one considers the kinetic and potential energy densities separately. These results are in agreement with mode-1 reflectivity of 0.7–1 from a model in one horizontal dimension with realistic topography and stratification. The direction of the incident internal tides is consistent with altimetry and modeling, while the reflected tide is consistent with specular reflection from a straight coastline.

scholarly journals The experimental and theoretical QTAIMC study of the atomic and molecular interactions in dinitrogen tetroxide

2009 ◽  
Vol 65 (5) ◽  
pp. 647-658 ◽  
Author(s):  
Vladimir G. Tsirelson ◽  
Anastasia V. Shishkina ◽  
Adam I. Stash ◽  
Simon Parsons
Keyword(s):  
Energy Density ◽  
Potential Energy ◽  
Electron Density ◽  
Molecular Interactions ◽  
Electrostatic Potential ◽  
Correlation Energy ◽  
Three Dimensional ◽  
Geometry Optimization ◽  
Intermolecular Bond ◽  
Experimental Electron Density

The atomic and molecular interactions in a crystal of dinitrogen tetraoxide, α-N2O4, have been studied in terms of the quantum topological theory of molecular structure using high-resolution, low-temperature X-ray diffraction data. The experimental electron density and electrostatic potential have been reconstructed with the Hansen–Coppens multipole model. In addition, the three-dimensional periodic electron density of crystalline α-N2O4 has been calculated at the B3LYP/cc-pVDZ level of theory with and without the geometry optimization. The application of the quantum theory of atoms in molecules and crystals (QTAIMC) recovered the two types of intermolecular bond paths between O atoms in crystalline α-N2O4, one measuring 3.094, the other 3.116 Å. The three-dimensional distribution of the Laplacian of the electron density around the O atoms showed that the lumps in the negative Laplacian fit the holes on the O atoms in the adjacent molecules, both atoms being linked by the intermolecular bond paths. This shows that the Lewis-type molecular complementarity contributes significantly to intermolecular bonding in crystalline N2O4. Partial overlap of atomic-like basins created by zero-flux surfaces in both the electron density and the electrostatic potential show that attractive electrostatic interaction exists between O atoms even though they carry the same net formal charge. The exchange and correlation contributions to the potential energy density were also computed by means of the model functionals, which use the experimental electron density and its derivatives. It was found that the intermolecular interactions in α-N2O4 are accompanied by the correlation energy-density `bridges' lowering the local potential energy along the intermolecular O...O bond paths in the electron density, while the exchange energy density governs the shape of bounded molecules.

Sign in / Sign up

Export Citation Format

Share Document