A Non-linear GPR Tomographic Inversion Algorithm Based on Iterated Cokriging and Conditional Simulations

2005 ◽  
pp. 409-418 ◽  
Author(s):  
E. Gloaguen ◽  
Denis Marcotte ◽  
M. Chouteau
Keyword(s):  
Inversion Algorithm ◽  
Tomographic Inversion ◽  
Conditional Simulations ◽  
Non Linear

Linearized tomographic inversion of first‐arrival times

Geophysics ◽  
1992 ◽  
Vol 57 (11) ◽  
pp. 1482-1492 ◽  
Author(s):  
James L. Simmons ◽  
Milo M. Backus
Keyword(s):  
Reference Model ◽  
Depth Range ◽  
Inversion Algorithm ◽  
Data Set ◽  
Tomographic Inversion ◽  
Seismic Reflection Data ◽  
Near Surface ◽  
Geometric Patterns ◽  
First Arrival ◽  
Thick Layers

A linearized tomographic‐inversion algorithm estimates the near‐surface slowness anomalies present in a conventional, shallow‐marine seismic reflection data set. First‐arrival time residuals are the data to be inverted. The anomalies are treated as perturbations relative to a known, laterally‐invariant reference velocity model. Below the sea floor the reference model varies smoothly with depth; consequently the first arrivals are considered to be diving waves. In the offset‐midpoint domain the geometric patterns of traveltime perturbations produced by the anomalies resemble hyperbolas. Based on simple ray theory, these geometric patterns are predictable and can be used to relate the unknown model to the data. The assumption of a laterally‐invariant reference model permits an efficient solution in the offset‐wavenumber domain which is obtained in a single step using conventional least squares. The tomographic image shows the vertical‐traveltime perturbations associated with the anomalies as a function of midpoint at a number of depths. As implemented, the inverse problem is inherently stable. The first arrivals sample the subsurface to a maximum depth of roughly 500 m (≈ one‐fifth of the spread length). The model is parameterized to consist of fifteen 20-m thick layers spanning a depth range of 80–380 m. One‐way vertical‐traveltime delays as large as 10 ms are estimated. Assuming that these time delays are distributed over the entire 20-m thick layers, velocities much slower than water velocity are implied for the anomalies. Maps of the tomographic images show the spatial location and orientation of the anomalies throughout the prospect for the upper 400 m. Each line is processed independently, and the results are corroborated to a high degree at the line intersections.

scholarly journals Application of an Adaptive Multi-Population Parallel Genetic Algorithm with Constraints in Electromagnetic Tomography with Incomplete Projections

2019 ◽  
Vol 9 (13) ◽  
pp. 2611
Author(s):  
Guo ◽  
Yang ◽  
Wu ◽  
Tan ◽  
Zhao
Keyword(s):  
Genetic Algorithm ◽  
Local Search ◽  
Search Algorithm ◽  
Field Tests ◽  
Premature Convergence ◽  
Projection Data ◽  
Parallel Genetic Algorithm ◽  
Inversion Algorithm ◽  
Tomographic Inversion ◽  
Electromagnetic Tomography

Electromagnetic tomography technology (EMT) is widely used in underground energy exploration. Limited by objective conditions, the collected projection data of electromagnetic waves are sparse and incomplete. Therefore, a study of the tomographic inversion algorithm of EMT based on incomplete projection data has an important guiding significance for the exploitation of underground energy. As a global optimization probability search algorithm, the simple genetic algorithm (SGA) has been widely used in the process of tomographic inversion. However, SGA evolves through a single population, and the values of crossover and mutation probability are always fixed, so there are risks of premature convergence and poor local search ability. To improve the performance of the SGA, a new approach of adaptive multi-population parallel genetic algorithm (AMPGA) with constraints is proposed in this paper. First, the AMPGA makes full use of multi-group adaptive co-evolution to improve the local and global search ability of SGA and restrain the risk of premature convergence. Then, the introduction of prior information as a constraint makes the results clearer and more accurate. The proposed algorithm has been verified in a numerical experiment and field tests, and the results show that the proposed algorithm can well balance global and local search capabilities, which offers a more realistic and stable tomographic result.

Generalizations of the non‐linear ocean‐SAR transform and a simplified SAR inversion algorithm

1994 ◽  
Vol 32 (1) ◽  
pp. 61-82 ◽  
Author(s):  
Harald E. Krogstad ◽  
Oddgeir Samset ◽  
Paris W. Vachon
Keyword(s):  
Inversion Algorithm ◽  
Non Linear

scholarly journals Investigation of the consistency of magnetic and soft x-ray plasma position measurements on TCV by means of a rapid tomographic inversion algorithm

2003 ◽  
Vol 45 (2) ◽  
pp. 169-180 ◽  
Author(s):  
J Mlynar ◽  
S Coda ◽  
A Degeling ◽  
B P Duval ◽  
F Hofmann ◽  
...  
Keyword(s):  
Inversion Algorithm ◽  
Tomographic Inversion ◽  
X Ray ◽  
Plasma Position

B. The Non-Linear Calculations for Pulsating Stars

1967 ◽  
Vol 28 ◽  
pp. 105-176
Author(s):  
Robert F. Christy
Keyword(s):  
Major Part ◽  
Afternoon Session ◽  
Discussion Session ◽  
Pulsating Stars ◽  
Fourth Symposium ◽  
Non Linear ◽  
Considerable Discussion ◽  
Informal Approach ◽  
Preceding Session

(Ed. note: The custom in these Symposia has been to have a summary-introductory presentation which lasts about 1 to 1.5 hours, during which discussion from the floor is minor and usually directed at technical clarification. The remainder of the session is then devoted to discussion of the whole subject, oriented around the summary-introduction. The preceding session, I-A, at Nice, followed this pattern. Christy suggested that we might experiment in his presentation with a much more informal approach, allowing considerable discussion of the points raised in the summary-introduction during its presentation, with perhaps the entire morning spent in this way, reserving the afternoon session for discussion only. At Varenna, in the Fourth Symposium, several of the summaryintroductory papers presented from the astronomical viewpoint had been so full of concepts unfamiliar to a number of the aerodynamicists-physicists present, that a major part of the following discussion session had been devoted to simply clarifying concepts and then repeating a considerable amount of what had been summarized. So, always looking for alternatives which help to increase the understanding between the different disciplines by introducing clarification of concept as expeditiously as possible, we tried Christy's suggestion. Thus you will find the pattern of the following different from that in session I-A. I am much indebted to Christy for extensive collaboration in editing the resulting combined presentation and discussion. As always, however, I have taken upon myself the responsibility for the final editing, and so all shortcomings are on my head.)

A decomposition method in non-linear programmm

Optimization ◽  
1975 ◽  
Vol 6 (4) ◽  
pp. 549-559
Author(s):  
L. Gerencsér
Keyword(s):  
Decomposition Method ◽  
Non Linear
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