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Gradient based technique for electromagnetic layered earth model data inversion

Gradient based technique for electromagnetic layered earth model data inversion. Claudio Patriarca, Andrea Di Matteo and Evert Slob. 2011 IEEE Internation Geoscience and Remote Sensing Symposium, Vancouver BC, July 2011. Local or Global inversion. Inversion Schemes. Gradient descent.

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Gradient based technique for electromagnetic layered earth model data inversion

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  1. Gradient based technique for electromagnetic layered earth model data inversion Claudio Patriarca, Andrea Di Matteo and Evert Slob 2011 IEEE Internation Geoscience and Remote Sensing Symposium, Vancouver BC, July 2011

  2. Local or Global inversion Inversion Schemes Gradient descent Global Multilevel Coordinate search

  3. Full-waveform inversion EM Inversion Schemes – non linear • Size of parameter space – nr. layers • Number of local minima - nonlinearity • Parameter correlations – limit sensitivity • UWB – many frequency points

  4. Towards local inversion Jacobian calculation Objective Function † Jacobian

  5. Jacobian calculation Numerical vs Explicit gradient • Numerically evaluated • Explicitly given

  6. Local Full-waveform inversion Numerical test case #1: smooth model

  7. Local Full-waveform inversion Numerical test case #1 result

  8. Full-waveform inversion Real data test case • Large datasets • UWB data (SFCW) Marble floor element in the Ancient theatre of Megalopolis, Greece

  9. Local Full-waveform inversion Real data test case

  10. Local Full-waveform inversion Real data test case results

  11. Local Full-waveform inversion Numerical test case #2: piecewise layered half-space

  12. Objective Function topography Numerical test case #2: piecewise layered half-space Global Minimum ε2 h2 ε1

  13. Conclusion • Local inversion advantages in moving downhill; problems with local minima • Comparison Global and Local search numerical and real data: success of local methods in specialized applications • Use explicit gradient • Deep interfaces? • Convenient implementing Hessian?

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