Inversion of P-SV seismic data

Geophysics ◽  
1986 ◽  
Vol 51 (5) ◽  
pp. 1056-1068 ◽  
Author(s):  
James J. Carazzone

In a layered elastic material, density, shear velocity, and compressional velocity can be found at any depth from broadband surface measurements at two distinct, nonzero, precritical values of plane‐wave incidence angle. Layer‐stripping inversion uses three‐component surface velocity measurements generated by a polarized surface source to determine subsurface properties incrementally. The surface velocity measurements initialize a first‐order, nonlinear, matrix Riccati equation (derived from the elastic wave equation) which takes advantage of an attractive fixed‐point condition in the complex frequency plane to extract subsurface mechanical impedances. Subsurface density and velocities are recovered from the inverted impedances at two or more plane‐wave incidence angles. General properties of the matrix Riccati equation in the complex frequency plane aid in incorporating bandwidth constraints. Inversion of synthetic plane wave data from a piece‐wise continuous model illustrates inversion effects when only a finite bandwidth is available and when different compressional and shear wavelength distance scales are present.

2011 ◽  
Vol 53 (1) ◽  
pp. 48-52 ◽  
Author(s):  
Emmanuelle Conil ◽  
Abdelhamid Hadjem ◽  
Azeddine Gati ◽  
Man-Fai Wong ◽  
Joe Wiart

2005 ◽  
Vol 15 (10) ◽  
pp. 1459-1468 ◽  
Author(s):  
GEORGE VENKOV

This paper deals with the scattering of time-harmonic acoustic waves by inhomogeneous medium. We study the problem to recover the near and the far field using a priori information about the refractive index and the support of inhomogeneity. The incident spherical wave is modified in such a way as to recover the plane wave incidence when the source point approaches infinity. Applying the low-frequency expansions, the scattering medium problem is reduced to a sequence of potential problems for the approximation coefficients in the presence of a monopole singularity located at the source of incidence. Complete expansions for the integral representation formula in the near field as well as for the scattering amplitude in the far field are provided. The method is applied to the case of a spherical region of inhomogeneity and a radial dependent refractive index. As the point singularity tends to infinity, the relative results recover the scattering medium problem for plane wave incidence.


2012 ◽  
Vol 48 (2) ◽  
pp. 795-798 ◽  
Author(s):  
Jin-Kyu Byun ◽  
Nak-Sun Choi ◽  
Dong-Hun Kim

2014 ◽  
Vol 2014 ◽  
pp. 1-4
Author(s):  
Antony J. Bourdillon

Accurate simulation from digital, submicron, optical elements is obtained by finite difference time domain (FDTD) results that are phase analyzed as sources for Huygens wavelets on fine scales much shorter than the wavelength used. Results, from the MIT electromagnetic evaluation program, are renormalized by a method here called “refractive impulse.” This is valid for polarized responses from digital diffractive and focusing optics. The method is employed with plane wave incidence at any angle or with diverging or converging beams. It is more systematic, more versatile, and more accurate than commercial substitutes.


2016 ◽  
Vol 15 ◽  
pp. 938-941
Author(s):  
Zheng-Yu Huang ◽  
Li-Hua Shi ◽  
Qing Si ◽  
Bin Chen

2021 ◽  
Author(s):  
Jiexi Yin ◽  
Qi Wu ◽  
Haiming Wang ◽  
Zhining Chen

<p>A prephase synthesis method is proposed for sidelobe level (SLL) suppression of a 1-bit phase-only control metasurface under plane wave incidence. The array factor of the metasurface with N×N unit cells shows that controlling the number of prephases with varying values over the reflective surface realizes equivalent amplitude tailoring. Different from optimizing the prephase distribution, selection of the numbers of 0 and π/2 prephases in specific N regions is used to suppress the SLLs. Therefore, the parameters in the optimization can be dramatically reduced from N<sup>2</sup> to N. The prephase distribution is then designed based on the optimized number of prephases and a symmetric matrix for SLL suppression in the whole space. The SLLs are further suppressed by optimizing some of the unit cell states based on similar equivalent amplitude tailoring. Simulation and measurement of a set of 1-bit reflective metasurfaces with 20×20 unit cells verify that the phase-only control metasurface realizes SLL suppression to -13 dB for multiple beam directions from -30 to 30 degrees with a 10-degree step under normal plane wave incidence.</p>


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