Study of Surface Effects on LG Wave Propagation in Heterogeneous Crusts by a GS-BE Hybrid Method

1998 ◽  
Author(s):  
R. S. Wu ◽  
T. Lay ◽  
X. B. Xie ◽  
L. Fu ◽  
S. Jin
Keyword(s):  
Wave Propagation ◽  
Hybrid Method ◽  
Surface Effects ◽  
Lg Wave

scholarly journals Lg wave propagation in the area around Japan: observations and simulations

2014 ◽  
Vol 1 (1) ◽  
pp. 10 ◽  
Author(s):  
Takashi Furumura ◽  
Tae-Kyung Hong ◽  
Brian LN Kennett
Keyword(s):  
Wave Propagation ◽  
Lg Wave

Electro-magneto wave propagation analysis of viscoelastic sandwich nanoplates considering surface effects

2016 ◽  
Vol 231 (2) ◽  
pp. 387-403 ◽  
Author(s):  
A Ghorbanpour Arani ◽  
M Jamali ◽  
AH Ghorbanpour-Arani ◽  
R Kolahchi ◽  
M Mosayyebi
Keyword(s):  
Zinc Oxide ◽  
Wave Propagation ◽  
Feedback Control ◽  
Graphene Sheet ◽  
Surface Effects ◽  
Structural Damping ◽  
Sensors And Actuators ◽  
Velocity Feedback ◽  
Oxide Layers ◽  
Propagation Analysis

The original formulation of the quasi-3D sinusoidal shear deformation plate theory (SSDPT) is here extended to the wave propagation analysis of viscoelastic sandwich nanoplates considering surface effects. The sandwich structure contains a single layered graphene sheet as core integrated with zinc oxide layers as sensors and actuators. The single layered graphene sheet and zinc oxide layers are subjected, respectively, to 2D magnetic and 3D electric fields. Structural damping and surface effects are assumed using Kelvin–Voigt and Gurtin–Murdoch theories, respectively. The system is rested on an elastic medium which is simulated with a novel model namely as orthotropic visco-Pasternak foundation. An exact solution is applied in order to obtain the frequency, cut-off and escape frequencies. A displacement and velocity feedback control algorithm is applied for the active control of the frequency through a closed-loop control with bonded distributed zinc oxide sensors and actuators. The detailed parametric study is conducted, focusing on the combined effects of the nonlocal parameter, magnetic field, viscoelastic foundation, surface stress, applied voltage, velocity feedback control gain and structural damping on the wave propagation behavior of nanostructure. Results depict that with increasing the structural damping coefficient, frequency significantly decreases.

A hybrid method to calculate teleseismic body waves in a regional 3D model using GEMINI and SPECFEM.

2021 ◽  
Author(s):  
Thomas Möller ◽  
Wolfgang Friederich
Keyword(s):  
Wave Propagation ◽  
Hybrid Method ◽  
Velocity Model ◽  
Absorbing Boundary Conditions ◽  
Body Waves ◽  
P Wave ◽  
Spherically Symmetric ◽  
Target Region ◽  
3D Simulations ◽  
Earth Models

<p>Modeling waveforms of teleseismic body waves requires the solution of the seismic wave equation in the entire Earth. Since fully-numerical 3D simulations on a global scale with periods of a few seconds are far too computationally expensive, we resort to a hybrid approach in which fully-numerical 3D simulations are performed only within the target region and wave propagation through the rest of the Earth is modeled using methods that are much faster but apply only to spherically symmetric Earth models.</p><p>We present a hybrid method that uses GEMINI to compute wave fields for a spherically symmetric Earth model up to the boundaries of a regional box. The wavefield is injected at the boundaries, where wave propagation is continued using SPECFEM-Cartesian. Inside the box, local heterogeneities in the velocity distribution are allowed, which can cause scattered and reflected waves. To prevent these waves from reflecting off the edges of the box absorbing boundary conditions are specifically applied to these parts of the wavefields. They are identified as the difference between the wavefield calculated with SPECFEM at the edges and the incident wavefield.</p><p>The hybrid method is applied to a target region in and around the Alps as a test case. The region covers an area of 1800 by 1350 km centered at 46.2°N and 10.87°E and includes crust and mantle to a depth of 600 km. We compare seismograms with a period of up to ten seconds calculated with the hybrid method to those calculated using GEMINI only for identical 1D earth models. The comparison of the seismograms shows only very small differences and thus validates the hybrid method. In addition, we demonstrate the potential of the method by calculating seismograms where the 1D velocity model inside the box is replaced by a velocity model generated using P-wave traveltime tomography.</p>

Two‐dimensional acoustic modeling by a hybrid method

Geophysics ◽  
1985 ◽  
Vol 50 (8) ◽  
pp. 1273-1284 ◽  
Author(s):  
V. Shtivelman
Keyword(s):  
Wave Propagation ◽  
Wave Field ◽  
Inhomogeneous Medium ◽  
Hybrid Method ◽  
Wave Scattering ◽  
Acoustic Modeling ◽  
Two Dimensional ◽  
Numerical Techniques ◽  
Numerical Examples ◽  
Field Computation

This paper follows previous work (Shtivelman, 1984) in which a hybrid method for wave‐field computation was developed. The method combines analytical and numerical techniques and is based upon separation of the processes of wave scattering and wave propagation. The method is further developed and improved; particularly, it is generalized for the case of an inhomogeneous medium above scattering objects (provided the inhomogeneity is weak, i.e., the effects of scattering can be neglected) and is represented by a simpler and more convenient form. Several numerical examples illustrating application of the method to the problems of two‐dimensional acoustic modeling are considered.

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