Transmission and reflection of Rayleigh wave through a step

1977 ◽  
Vol 67 (5) ◽  
pp. 1277-1290
Author(s):  
L. Martel ◽  
M. Munasinghe ◽  
G. W. Farnell
Keyword(s):  
Rayleigh Wave ◽  
Phase Shifts ◽  
Body Waves ◽  
Reflected Wave ◽  
Homogeneous Half Space ◽  
Transmission And Reflection Coefficients ◽  
Group Delays ◽  
Seismic Models ◽  
Transmission And Reflection ◽  
Good Agreement

abstract The transmission and reflection of a Rayleigh wave through a step on a homogeneous half-space of Poisson's ratio σ = 0.253 have been investigated by a seismic models method. The experimental results show good agreement with numerical ones obtained by finite-difference calculations when the wave is incident onto a downward step. Phase shifts are given both for the upward and downward steps. The characteristics of the transmitted wave do not depend much on the direction of propagation but those of the reflected wave are clearly direction-dependent. In each case the transmission and reflection coefficients and phase shifts depend on the ratio of step height to wavelength. The group delays are calculated and they are positive or negative depending on the period. About 80 per cent of the incident energy is converted into body waves when the step is higher than 0.3 times the wavelength of the Rayleigh wave.

scholarly journals Optically Transparent Metasurface Absorber Based on Reconfigurable and Flexible Indium Tin Oxide Film

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1032
Author(s):  
Lei Chen ◽  
Ying Ruan ◽  
Si Si Luo ◽  
Fu Ju Ye ◽  
Hao Yang Cui
Keyword(s):  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Air Permeability ◽  
Ultra Wideband ◽  
Reflection Coefficients ◽  
Transmission And Reflection Coefficients ◽  
Ito Film ◽  
Optically Transparent ◽  
Transmission And Reflection ◽  
Good Agreement

In this paper, we present a flexible, breathable and optically transparent metasurface with ultra-wideband absorption. The designed double layer of indium tin oxide (ITO) films with specific carved structure realizes absorption and electromagnetic (EM) isolation in dual-polarization, as well as good air permeability. Under the illumination of x- and y-polarization incidence, the metasurface has low reflectivity and transmission from about 2 to 18 GHz. By employing ITO film based on polyethylene terephthalate (PET), the presented metasurface also processes the excellent flexibility and optically transparency, which can be utilized for wearable device application. In addition, the dual-layer design enables mechanically-reconfigurable property of the metasurface. The transmission and reflection coefficients in two polarizations show distinct difference when arranging the different relevant positions of two layers of the metasurface. A sample with 14*14 elements is designed, fabricated and measured, showing good agreement with the simulation results. We envision this work has various potentials in the wearable costume which demands both EM absorption and isolation.

Transmission of Rayleigh waves at a corner

1966 ◽  
Vol 56 (2) ◽  
pp. 455-466 ◽  
Author(s):  
A. K. Mal ◽  
L. Knopoff
Keyword(s):  
Integral Equations ◽  
Rayleigh Waves ◽  
Wedge Angle ◽  
Body Waves ◽  
Algebraic Equations ◽  
Reflected Waves ◽  
Transmission And Reflection Coefficients ◽  
Transmitted Waves ◽  
New Feature ◽  
Transmission And Reflection

abstract Using a Green's function method of approximation, transmission and reflection coefficients are computed for the problem of Rayleigh waves normally incident upon the corner of a homogeneous elastic wedge formed by two stress-free planes. The Rayleigh waves are incident from infinity and travel along one surface of the wedge. The transmitted waves on the second surface and the reflected waves on the first surface are calculated by the application of Huygens' principle. A pair of coupled integral equations for the displacements are obtained by means of a representation theorem. Neglecting the diffracted body waves near the corner, the coupled integral equations are reduced to a pair of algebraic equations. A new feature of the calculation involves consideration of diffracted surface waves travelling toward the vertex. Numberical values of the phase shifts and attenuation factors in the transmitted and reflected waves are computed as functions of the wedge angle. Comparison with experimental results show considerably better agreement than has been obtained previously.

scholarly journals Budgets of Disturbances Energy for Nozzle Flows at Subsonic and Choked Regimes

2017 ◽  
Author(s):  
Maxime Huet
Keyword(s):  
Acoustic Energy ◽  
Energy Budgets ◽  
Acoustic Transmission ◽  
Test Rig ◽  
Transmission And Reflection Coefficients ◽  
Energetic Approach ◽  
Acoustic Fluctuations ◽  
Nozzle Flows ◽  
Transmission And Reflection ◽  
Good Agreement

The noise generated by the passage of acoustic and entropy perturbations through subsonic and choked nozzle flows is investigated numerically using an energetic approach. Low-order models are used to reproduce the experimental results of the Hot Acoustic Test rig (HAT) of DLR and energy budgets are performed to characterize the reflection, transmission and dissipation of the fluctuations. Because acoustic and entropy perturbations are present in the flow in the general case, classical acoustic energy budgets cannot be used and the disturbances energy budgets proposed by Myers (J. Fluid Mech. 226 (1991) 383–400) are used instead. Numerical results are in very good agreement with the experiments in terms of acoustic transmission and reflection coefficients. The normal shock present in the diffuser for choked regimes is shown to attenuate the scattered acoustic fluctuations, either by pure dissipation effect or by converting a part of the acoustic energy into entropy fluctuations.

scholarly journals Budgets of Disturbances Energy for Nozzle Flows at Subsonic and Choked Regimes

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Maxime Huet
Keyword(s):  
Acoustic Energy ◽  
Energy Budgets ◽  
Steady Flows ◽  
Test Rig ◽  
Transmission And Reflection Coefficients ◽  
Energetic Approach ◽  
Acoustic Fluctuations ◽  
Nozzle Flows ◽  
Transmission And Reflection ◽  
Good Agreement

The noise generated by the passage of acoustic and entropy perturbations through subsonic and choked nozzle flows is investigated numerically using an energetic approach. Low-order models are used to reproduce the experimental results of the hot acoustic test rig (HAT) of Deutsches Zentrum für Luft- und Raumfahrt (DLR), and energy budgets are performed to characterize the reflection, transmission, and dissipation of the fluctuations. Because acoustic and entropy perturbations are present in the flow in the general case, classical acoustic energy budgets cannot be used and the disturbances energy budgets proposed by Myers (1991, “Transport of Energy by Disturbances in Arbitrary Steady Flows,” J. Fluid Mech., 226, pp. 383–400.) are used instead. Numerical results are in very good agreement with the experiments in terms of acoustic transmission and reflection coefficients. The normal shock present in the diffuser for choked regimes is shown to attenuate the scattered acoustic fluctuations, either by pure dissipation effect or by converting a part of the acoustic energy into entropy fluctuations.

TRANSMISSION AND REFLECTION OF RAYLEIGH WAVES AT CORNERS

Geophysics ◽  
1958 ◽  
Vol 23 (2) ◽  
pp. 253-266 ◽  
Author(s):  
J. Cl. de Bremaecker
Keyword(s):  
Surface Wave ◽  
Rayleigh Wave ◽  
Rayleigh Waves ◽  
Body Waves ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Reflection And Transmission ◽  
Two Dimensional Model ◽  
Model Seismology ◽  
Transmission And Reflection

The methods of two dimensional model seismology were used to investigate the phenomena occurring when a Rayleigh wave is incident upon a corner whose angle is comprised between 0° and 180°. The wave bends its path only for angles between 130° and 180°. For smaller angles large and abrupt variations in reflection and transmission occur; the wave travels to the extremity of the corner and never “cuts corners”; only about 50 percent of the energy of the indicent surface wave is preserved as such, the rest goes into body waves; for a 90° corner the proportion is about 23 percent in P and 26 percent in S, with sharply preferential angles of incidence. The percentages given were found for a “plate Poisson’s ratio” of 0.17.

Transformation of internal waves passing over a bottom step

2015 ◽  
Vol 768 ◽  
Author(s):  
Egor N. Churaev ◽  
Sergey V. Semin ◽  
Yury A. Stepanyants
Keyword(s):  
Internal Waves ◽  
Density Ratio ◽  
Numerical Data ◽  
Wave Transformation ◽  
Reflection Coefficients ◽  
Approximate Theory ◽  
Transmission And Reflection Coefficients ◽  
Transmission And Reflection ◽  
Good Agreement ◽  
Bottom Step

The transformation of small-amplitude internal waves on the oceanic shelf is studied numerically. The transmission and reflection coefficients are found for the simplified step-wise model of the oceanic shelf in a two-layer fluid. The approximate formulae are proposed for the transformation coefficients as functions of incident wavenumber, density ratio of layers, depth of the pycnocline and height of the bottom step. Results of direct numerical modelling of internal wave transformation are obtained and presented as functions of all aforementioned parameters. It is shown that there is a good agreement between the outcomes of approximate theory and numerical data. Both the theoretical and the numerical results agree well with the law of energy flux conservation.

Transmission of Rayleigh waves past a step change in elevation

1965 ◽  
Vol 55 (2) ◽  
pp. 319-334 ◽  
Author(s):  
A. K. Mal ◽  
L. Knopoff
Keyword(s):  
Surface Waves ◽  
Half Space ◽  
Green's Function ◽  
Rayleigh Waves ◽  
Function Method ◽  
Step Change ◽  
Reflection Coefficients ◽  
Homogeneous Half Space ◽  
Transmission And Reflection Coefficients ◽  
Transmission And Reflection

Abstract Using a Green's function method of approximation, transmission and reflection coefficients are computed for the problem of Rayleigh waves incident upon a step change in the elevation of the surface of a homogeneous half-space. Several versions of these approximations are given, differing principally by the method in which the surface waves on the vertical face of the step are taken into account.

scholarly journals Transmission, Reflection and Dissipation of Microwaves in Magnetic Composites with Nanocrystalline Finemet-Type Flakes

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3499
Author(s):  
Anatoly B. Rinkevich ◽  
Dmitry V. Perov ◽  
Yuriy I. Ryabkov
Keyword(s):  
Composite Material ◽  
Microwave Absorption ◽  
Nanocrystalline Alloy ◽  
Reflection Coefficients ◽  
Magnetic Composites ◽  
Transmission And Reflection Coefficients ◽  
Wave Interference ◽  
Microwave Losses ◽  
Frequency Dependences ◽  
Transmission And Reflection

The microwave properties of a composite material containing flakes of finemet-type nanocrystalline alloy placed in the epoxy matrix have been investigated. Two compositions have been studied: with 15% and 30% flakes. Frequency dependences of transmission and reflection coefficients are measured in the frequency range from 12 to 38 GHz. The dielectric permittivity and magnetic permeability are obtained, and the microwave losses are calculated. The dependences of transmission and reflection coefficients have been drawn as functions of wave frequency and thickness of the composite material, taking into account the frequency dependences of permittivity and permeability. The regions of maximal and minimal microwave absorption have been defined. The influence of wave interference on the frequency dependence of microwave absorption is studied.

Sign in / Sign up

Export Citation Format

Share Document