scholarly journals Fracture properties from seismic data – a numerical investigation

2002 ◽  
Vol 29 (4) ◽  
Author(s):  
Aoife Toomey
Keyword(s):  
Numerical Investigation ◽  
Seismic Data ◽  
Fracture Properties

Determination of background velocities by multiple migration fitting

Geophysics ◽  
1995 ◽  
Vol 60 (2) ◽  
pp. 476-490 ◽  
Author(s):  
Guy Chavent ◽  
Chester A. Jacewitz
Keyword(s):  
Numerical Investigation ◽  
Seismic Data ◽  
Synthetic Data ◽  
Similarity Index ◽  
Velocity Profiles ◽  
Additional Cost ◽  
Scalar Similarity ◽  
Local Gradient

We present an approach called multiple migration fitting (MMF) designed to automatically determine 2-D background velocities from prestack seismic data. In this approach, we maximize a scalar similarity index (SI) for a collection of migrated sections obtained by various illuminations of the same earth. Numerical investigation shows that this index is a rather smooth, nonoscillatory function of velocity that tends to be a maximum for good velocity profiles, and hence is amenable to maximization by local gradient techniques. This maximization will be practically feasible, as we prove that the exact gradient of SI can be computed at an additional cost of only twice that required for the computation of the collection of migrated sections, independently of the number of velocity unknowns. Application to synthetic data shows that MMF leads to enhanced background velocities and stacked migrated sections.

Numerical Investigation of Discharge Current Path in a Hydrogen MPD Thruster

2016 ◽  
Vol 136 (3) ◽  
pp. 141-146 ◽  
Author(s):  
Akira Kawasaki ◽  
Kenichi Kubota ◽  
Ikkoh Funaki ◽  
Yoshihiro Okuno
Keyword(s):  
Numerical Investigation ◽  
Discharge Current ◽  
Current Path
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