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Acoustic wave

About: Acoustic wave is a research topic. Over the lifetime, 31105 publications have been published within this topic receiving 452832 citations. The topic is also known as: sound wave & pressure wave.


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Journal ArticleDOI
TL;DR: In this article, an elastic finite-difference method is used to perform an inversion for P-wave velocity, S-wave impedance, and density, which is based on nonlinear least squares and proceeds by iteratively updating the earth parameters.
Abstract: The treatment of multioffset seismic data as an acoustic wave field is becoming increasingly disturbing to many geophysicists who see a multitude of wave phenomena, such as amplitude-offset variations and shear-wave events, which can only be explained by using the more correct elastic wave equation. Not only are such phenomena ignored by acoustic theory, but they are also treated as undesirable noise when they should be used to provide extra information, such as S-wave velocity, about the subsurface. The problems of using the conventional acoustic wave equation approach can be eliminated via an elastic approach. In this paper, equations have been derived to perform an inversion for P-wave velocity, S-wave velocity, and density as well as the P-wave impedance, S-wave impedance, and density. These are better resolved than the Lame parameters. The inversion is based on nonlinear least squares and proceeds by iteratively updating the earth parameters until a good fit is achieved between the observed data and the modeled data corresponding to these earth parameters. The iterations are based on the preconditioned conjugate gradient algorithm. The fundamental requirement of such a least-squares algorithm is the gradient direction which tells how to update the model parameters. The gradient direction can be derived directly from the wave equation and it may be computed by several wave propagations. Although in principle any scheme could be chosen to perform the wave propagations, the elastic finite-difference method is used because it directly simulates the elastic wave equation and can handle complex, and thus realistic, distributions of elastic parameters. This method of inversion is costly since it is similar to an iterative prestack shot-profile migration. However, it has greater power than any migration since it solves for the P-wave velocity, S-wave velocity, and density and can handle very general situations including transmission problems. Three main weaknesses of this technique are that it requires fairly accurate a priori knowledge of the low-wavenumber velocity model, it assumes Gaussian model statistics, and it is very computer-intensive. All these problems seem surmountable. The low-wavenumber information can be obtained either by a prior tomographic step, by the conventional normal-moveout method, by a priori knowledge and empirical relationships, or by adding an additional inversion step for low wavenumbers to each iteration. The Gaussian statistics can be altered by preconditioning the gradient direction, perhaps to make the solution blocky in appearance like well logs, or by using large model variances in the inversion to reduce the effect of the Gaussian model constraints. Moreover, with some improvements to the algorithm and more parallel computers, it is hoped the technique will soon become routinely feasible.

872 citations

Proceedings Article
W. P. Arnott1, R. Raspet1, H.E. Bass1
01 Jan 1991
TL;DR: In this paper, an approximate analysis of energy flow and acoustical measurements of a thermoacoustic prime mover with arbitrary cross-sectional geometry is given. But this analysis is restricted to the case of TAEs with circular or parallel slit pore geometry.
Abstract: Thermoacoustic engines (TAEs) can be used to pump heat using a sound wave or pump a sound wave using a temperature gradient. The basic arrangement is a gas-filled acoustic resonator with appropriately positioned thermoacoustic elements. Two types of thermoacoustic elements are used in these engines: (1) heat exchangers used to communicate heat between the gas and external heat reservoirs; and (2) the TAE, also known as a stack. The TAEs are sections of porous media that support the temperature gradient, transport heat on the acoustic wave between the exchangers, and produce or absorb acoustic power. Previous results have been developed for TAEs with circular or parallel slit pore geometries. The theory is extended for gas-filled TAEs to include pores of arbitrary cross-sectional geometry. An approximate analysis of energy flow and acoustical measurements of a thermoacoustic prime mover are given. >

821 citations

Book
01 Jan 1997
TL;DR: In this article, the authors present a detailed comparison of typical mass sensitivity of Acoustic Sensors Typical Mass Sensitivities of acoustic Wave Devices Classification of Coating-Analyte Interactions and Approximate Energies Adsorbent Materials and Typical Adsorbates Adsorption Capacities of Organic Vapors on Activated Charcoal Examples of Adsors-Based Acoustic Wave Sensors Sorption Capacity of Natural Rubber for Several Organic Solvents Typical Examples of Polymer-Coated Acoustic wave sensors Examples of Biochemical Acoustic-Wave Sensors Cluster
Abstract: Why Acoustic Sensors Fundamentals of Acoustic Wave Devices Acoustic Wave Sensors and Responses Materials Characterization Chemical and Biological Sensors Practical Aspects of Acoustic-Wave Sensors Subject Index Reduced Index Notation Mechanical Properties of Selected Materials Piezoelectric Stress Constants Properties of Several SAW Substrate Materials Acoustoelectric Properties of Several SAW Substrate Materials Moduli Associated with the Strain Modes Generated by a SAW in an Acoustically Thin Film SAW-Film Coupling Parameter and Phase Angles for SAW Propagation in the X-Direction of ST-Cut Quartz FPW Density Determinations for Low-Viscosity Liquids Gravimetric Sensitivities of Acoustic Sensors Qualitative Comparison of Acoustic Sensors Typical Mass Sensitivities of Acoustic Wave Devices Classification of Coating-Analyte Interactions and Approximate Energies Adsorbent Materials and Typical Adsorbates Adsorption Capacities of Organic Vapors on Activated Charcoal Examples of Adsorption-Based Acoustic Wave Sensors Sorption Capacity of Natural Rubber for Several Organic Solvents Typical Examples of Polymer-Coated Acoustic Wave Sensors Examples of Biochemical Acoustic Wave Sensors Cluster Classification of Coatings for Use in a TSM Sensor Array Center Frequency and Dimensions of Commercial TSM AT-Quartz Resonators IDT Design Parameters for ST-Quartz-Based SAW Sensor Devices"

775 citations

Book
01 Jan 1982
TL;DR: The ocean as an acoustical medium ray theory of the sound field in the ocean reflection of sound from the surface and bottom of the ocean plane was proposed in this article, where sound propagation in the random ocean scattering and absorption of sound by gas bubbles in water.
Abstract: The ocean as an acoustical medium ray theory of the sound field in the ocean reflection of sound from the surface and bottom of the ocean plane waves reflection of sound from the surface and bottom of the ocean point source propagation of sound in shallow water underwater sound channel (USC) range-dependent waveguide antiwave guide sound propagation scattering of sound at rough surfaces sound propagation in the random ocean scattering and absorption of sound by gas bubbles in water.

739 citations

Journal ArticleDOI
TL;DR: In this article, Batchelor's approximate equations of motion were derived by a formal scale analysis, with the assumption that the percentage range in potential temperature is small and that the time scale is set by the Brunt-Vaisala frequency.
Abstract: The approximate equations of motion derived by Batchelor in 1953 are derived by a formal scale analysis, with the assumption that the percentage range in potential temperature is small and that the time scale is set by the Brunt-Vaisala frequency. Acoustic waves are then absent. If the vertical scale is small compared to the depth of an adiabatic atmosphere, the system reduces to the (non-viscous) Boussinesq equations. The computation of the saturation vapor pressure for deep convection is complicated by the important effect of the dynamic pressure on the temperature. For shallow convection this effect is not important, and a simple set of reversible equations is derived.

726 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023127
2022275
2021800
2020942
2019989
20181,032