scholarly journals Phase and amplitude correction for multi-echo water-fat separation with bipolar acquisitions

2010 ◽  
Vol 31 (5) ◽  
pp. 1264-1271 ◽  
Author(s):  
Huanzhou Yu ◽  
Ann Shimakawa ◽  
Charles A. McKenzie ◽  
Wenmiao Lu ◽  
Scott B. Reeder ◽  
...  
Keyword(s):  
Amplitude Correction

DIVERGENCE EFFECTS IN A LAYERED EARTH

Geophysics ◽  
1973 ◽  
Vol 38 (3) ◽  
pp. 481-488 ◽  
Author(s):  
P. Newman
Keyword(s):  
Normal Incidence ◽  
Wave Theory ◽  
Diagnostic Value ◽  
Earth Model ◽  
Correction Factors ◽  
Amplitude Correction ◽  
Multiple Attenuation ◽  
Seismic Recording ◽  
Zero Offset ◽  
Special Case

Of the various factors which influence reflection amplitudes in a seismic recording, divergence effects are possibly of least direct interest to the interpreter. Nevertheless, proper compensation for these effects is mandatory if reflection amplitudes are to be of diagnostic value. For an earth model consisting of horizontal, isotropic layers, and assuming a point source, we apply ray theory to determine an expression for amplitude correction factors in terms of initial incidence, source‐receiver offset, and reflector depth. The special case of zero offset yields an expression in terms of two‐way traveltime, velocity in the initial layer, and the time‐weighted rms velocity which characterizes reflections. For this model it follows that information which is needed for divergence compensation in the region of normal incidence is available from the customary analysis of normal moveout (NMO). It is hardly surprising that NMO and divergence effects are intimately related when one considers the expanding wavefront situation which is responsible for both phenomena. However, it is evident that an amplitude correction which is appropriate for the primary reflection sequence cannot in general be appropriate for the multiples. At short offset distances the disparity in displayed amplitude varies as the square of the ratio of primary to multiple rms velocities, and favors the multiples. These observations are relevant to a number of concepts which are founded upon plane‐wave theory, notably multiple attenuation processes and record synthesis inclusive of multiples.

Paraxial theory of amplitude correction

1992 ◽  
Author(s):  
Kaiyun Wang ◽  
Jin-wen Sun ◽  
Wei Zhang
Keyword(s):  
Amplitude Correction

Fast acquisition aperture correction in prestack depth migration using beamlet decomposition

Geophysics ◽  
2009 ◽  
Vol 74 (4) ◽  
pp. S67-S74 ◽  
Author(s):  
Jun Cao ◽  
Ru-Shan Wu
Keyword(s):  
Wave Equation ◽  
Correction Factor ◽  
Computing Time ◽  
Computation Time ◽  
Prestack Depth Migration ◽  
Depth Migration ◽  
Wavenumber Domain ◽  
Amplitude Correction ◽  
Local Wavenumber ◽  
Local Angle

Wave-equation-based acquisition aperture correction in the local angle domain can improve image amplitude significantly in prestack depth migration. However, its original implementation is inefficient because the wavefield decomposition uses the local slant stack (LSS), which is demanding computationally. We propose a faster method to obtain the image and amplitude correction factor in the local angle domain using beamlet decomposition in the local wavenumber domain. For a given frequency, the image matrix in the local wavenumber domain for all shots can be calculated efficiently. We then transform the shot-summed image matrix from the local wavenumber domain to the local angle domain (LAD). The LAD amplitude correction factor can be obtained with a similar strategy. Having a calculated image and correction factor, one can apply similar acquisition aperture corrections to the original LSS-based method. For the new implementation, we compare the accuracy and efficiency of two beamlet decompositions: Gabor-Daubechies frame (GDF) and local exponential frame (LEF). With both decompositions, our method produces results similar to the original LSS-based method. However, our method can be more than twice as fast as LSS and cost only twice the computation time of traditional one-way wave-equation-based migrations. The results from GDF decomposition are superior to those from LEF decomposition in terms of artifacts, although GDF requires a little more computing time.

Amplitude Correction Method of Time-Wavelength Interleaved Photonic Analog-to-Digital Conversion

2016 ◽  
Vol 43 (5) ◽  
pp. 0505001
Author(s):  
叶雷 Ye Lei ◽  
吴龟灵 Wu Guiling ◽  
苏斐然 Su Feiran ◽  
陈建平 Chen Jianping
Keyword(s):  
Correction Method ◽  
Digital Conversion ◽  
Analog To Digital ◽  
Amplitude Correction ◽  
Analog To Digital Conversion

Transfer Matrix Study of Finite-size Corrections in the 2D Ising Model

2005 ◽  
Vol 5 (1) ◽  
pp. 72-85 ◽  
Author(s):  
J. Kaupužs
Keyword(s):  
Correlation Function ◽  
Ising Model ◽  
Transfer Matrix ◽  
Finite Size ◽  
Lattice Systems ◽  
Small Magnitude ◽  
Amplitude Correction ◽  
Matrix Algorithms ◽  
Point Correlation ◽  
Point Correlation Function

AbstractEffective exact transfer matrix algorithms have been developed to compute the two-point correlation function G(r) of the 2D Ising model on a square finite size lattice. Systems including up to 800 spins have been considered and corrections to the finite-size scaling at the critical point have been analysed.As a new result, we have found that the correlation function has a nontrivial amplitude correction of a very small magnitude.

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