Attenuation and dispersion effects of nonequilibrium molecular processes on acoustic waves in cylindrical tube

1982 ◽  
Vol 72 (4) ◽  
pp. 1264-1268
Author(s):  
William W. Peng
Keyword(s):  
Acoustic Waves ◽  
Cylindrical Tube ◽  
Molecular Processes ◽  
Dispersion Effects ◽  
Attenuation And Dispersion

Attenuation and dispersion of longitudinal acoustic waves in α‐sulphur

1974 ◽  
Vol 45 (7) ◽  
pp. 2855-2857 ◽  
Author(s):  
René Vacher ◽  
Jacques Sapriel ◽  
Maurice Boissier
Keyword(s):  
Acoustic Waves ◽  
Longitudinal Acoustic ◽  
Longitudinal Acoustic Waves ◽  
Attenuation And Dispersion

scholarly journals Attenuation and Dispersion on Terahertz Wireless Channels in Falling Rain

2021 ◽  
Author(s):  
Jianjun Ma ◽  
Peian Li ◽  
Liangbin Zhao ◽  
Jianchen Wang ◽  
Wenbo Liu ◽  
...  
Keyword(s):  
Wireless Channel ◽  
Water Vapor Absorption ◽  
Dispersion Effects ◽  
Communication Technique ◽  
Vapor Absorption ◽  
Terahertz Communication ◽  
Channel Performance ◽  
Spectrometer System ◽  
Attenuation And Dispersion ◽  
Temporal Dispersion

Abstract Investigations on wireless channel performance in adverse weathers could be helpful and important for the future applications of terahertz communication technique in outdoor scenarios. However, in most cases only amplitude performance has been studied by using a broadband-pulsed terahertz source or an amplitude modulated data stream, not including phase degradation (temporal dispersion). This limitation may mask important aspects of channel performance with phase modulation schemes, especially for wide bandwidth signals. In this work, we report the amplitude and phase characterizations of a terahertz channel in falling rain by a time-domain spectrometer system. We also demonstrate error rate performance by a 16 quadrature amplitude modulated (16-QAM) terahertz signal at a data rate of 5 gigabits per second. We observe that, besides strong water vapor absorption, the weak water absorption line could also lead to obvious dispersion effects. Our work highlights the importance of new frequency band boundaries for minimum temporal dispersion and optimized digital communications in the terahertz frequency range.

scholarly journals Modeling attenuation and dispersion of acoustic waves in porous media containing immiscible non viscous fluids

DYNA ◽  
2016 ◽  
Vol 83 (199) ◽  
pp. 78 ◽  
Author(s):  
Alejandro Duitama Leal ◽  
Ovidio Almanza ◽  
Luis Alfredo Montes Vides
Keyword(s):  
Porous Media ◽  
Acoustic Waves ◽  
Viscous Fluids ◽  
Attenuation And Dispersion

Este artículo reporta resultados de la propagación de ondas P en medios porosos, simulada solucionando en diferencias finitas las ecuaciones generalizadas de Biot. En modelos saturados se observó que cuando avanza la onda, la amplitud máxima del espectro se desplaza hacia frecuencias menores, y que esta amplitud máxima y su frecuencia están directamente relacionadas. Además, que el factor de calidad disminuye con la porosidad y la saturación. Por ende, la atenuación aumenta con la porosidad, la saturación y la frecuencia pero tiende asintóticamente a un valor constante. Se observó que la fase de la onda cambia linealmente con la frecuencia a una rata de cambio que aumenta linealmente con el tiempo de viaje. Esta rata aumenta con la saturación pero disminuye ligeramente con la porosidad. Este trabajo ignora la divergencia esférica y la retro dispersión, concentrándose en la atenuación intrínseca causada por la fricción, en particular entre líquido y partículas sólidas.

Modeling acoustic wave propagation in heterogeneous attenuating media using decoupled fractional Laplacians

Geophysics ◽  
2014 ◽  
Vol 79 (3) ◽  
pp. T105-T116 ◽  
Author(s):  
Tieyuan Zhu ◽  
Jerry M. Harris
Keyword(s):  
Wave Propagation ◽  
Wave Equation ◽  
Acoustic Wave ◽  
Time Domain ◽  
Heterogeneous Media ◽  
Acoustic Wave Propagation ◽  
Pierre Shale ◽  
Dispersion Effects ◽  
Temporal Derivative ◽  
Attenuation And Dispersion

We evaluated a time-domain wave equation for modeling acoustic wave propagation in attenuating media. The wave equation was derived from Kjartansson’s constant-[Formula: see text] constitutive stress-strain relation in combination with the mass and momentum conservation equations. Our wave equation, expressed by a second-order temporal derivative and two fractional Laplacian operators, described very nearly constant-[Formula: see text] attenuation and dispersion effects. The advantage of using our formulation of two fractional Laplacians over the traditional fractional time derivative approach was the avoidance of time history memory variables and thus it offered more economic computations. In numerical simulations, we formulated the first-order constitutive equations with the perfectly matched layer absorbing boundaries. The temporal derivative was calculated with a staggered-grid finite-difference approach. The fractional Laplacians are calculated in the spatial frequency domain using a Fourier pseudospectral implementation. We validated our numerical results through comparisons with theoretical constant-[Formula: see text] attenuation and dispersion solutions, field measurements from the Pierre Shale, and results from 2D viscoacoustic analytical modeling for the homogeneous Pierre Shale. We also evaluated different formulations to show separated amplitude loss and dispersion effects on wavefields. Furthermore, we generalized our rigorous formulation for homogeneous media to an approximate equation for viscoacoustic waves in heterogeneous media. We then investigated the accuracy of numerical modeling in attenuating media with different [Formula: see text]-values and its stability in large-contrast heterogeneous media. Finally, we tested the applicability of our time-domain formulation in a heterogeneous medium with high attenuation.

Prestack depth migration with compensation for absorption and dispersion

Geophysics ◽  
1995 ◽  
Vol 60 (5) ◽  
pp. 1485-1494 ◽  
Author(s):  
Rune Mittet ◽  
Roger Sollie ◽  
Ketil Hokstad
Keyword(s):  
Phase Velocity ◽  
Optimization Algorithm ◽  
Design Criterion ◽  
Prestack Depth Migration ◽  
Depth Migration ◽  
Dispersion Effects ◽  
Wavefield Extrapolation ◽  
Absorption And Dispersion ◽  
Attenuation And Dispersion ◽  
High Absorption

In prestack depth migration using explicit extrapolators, the attenuation and dispersion of the seismic wave has been neglected so far. We present a method for accommodating absorption and dispersion effects in depth migration schemes. Extrapolation operators that compensate for absorption and dispersion are designed using an optimization algorithm. The design criterion is that the wavenumber response of the operator should equal the true extrapolator. Both phase velocity and absorption macro models are used in the wavefield extrapolation. In a model with medium to high absorption, the images obtained are superior to those obtained using extrapolators without compensation for absorption.

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