[CIG-SEISMO] time reversed computation in specfem2d

[Chris Morency]

Hi Dimitri and Jörg,

Yes, it being done in the weeks to come is definitively my priority.
Running a type of benchmark with Jörg's code sounds great. I will keep 
in touch.

Thanks,
Christina

Dimitri Komatitsch wrote:
>
> Hi Christina,
>
> No problem at all, doing it in the next few weeks or months
> is fine! Jörg can probably help for the tests since he had planned to 
> develop an adjoint code from scratch anyway. Running a few tests with 
> an existing code will be much faster.
>
> Thanks,
> Dimitri.
>
> Chris Morency wrote:
>> Hello Dimitri,
>>
>> I feel it is actually my bad ! As you know, we had discussed the 
>> merging of the 2D version we have been developing including 
>> poroelasticity. This version does have the adjoint capabilities for 
>> acoustic, elastic, and poroelastic media. It is still on a branch....
>> I am finishing dealing with some domain decomposition issues when 
>> using irregular (CUBIT generated) meshes. It shouldn't be too long 
>> and then I should be able to fully merge this new version in place of 
>> the present specfem2D.
>> Really sorry about that. I am presently working on it.
>>
>> Christina
>>
>> Dimitri Komatitsch wrote:
>>>
>>> Dear Jörg and Carl,
>>>
>>> This has been done already, by Carl Tape et al. from Caltech (USA).
>>> See for instance their papers below and in PDF at 
>>> http://www.gps.caltech.edu/~carltape/research/CV.html#Pubs
>>>
>>> I thought the kernel capability and adjoint runs had been added to 
>>> SPECFEM2D already (on the SVN server). Carl, did you do it?
>>> We talked about it (merging your kernels in the SVN code) two years ago
>>> and I thought that it had been done since then. If not, would it be 
>>> easy to do? It would clearly be very useful. As always, working on a 
>>> local version not under SVN control was a bad idea to begin with... 
>>> because now it is a dead branch... could somebody (maybe Jörg) cut 
>>> and paste your adjoint routines in the SVN code? (if you sent him a 
>>> copy of your old 2D code)
>>>
>>> In the future let us all use SVN all the time from the beginning of 
>>> any new SPECFEM project.
>>>
>>> Thanks,
>>> Cheers,
>>>
>>> Dimitri.
>>>
>>> Tape, C., Liu, Q., and J. Tromp, 2007, Finite-frequency tomography 
>>> using adjoint methods---Methodology and examples using membrane 
>>> surface waves,  Geophysical Journal International, v. 168, 1105-1129.
>>>
>>>
>>> Tromp, J., Tape, C., and Q. Liu, 2005, Seismic tomography, adjoint 
>>> methods, time reversal, and banana-doughnut kernels, Geophysical 
>>> Journal International, v. 160, p. 195-216.
>>>
>>>
>>> pge05bqw at studserv.uni-leipzig.de wrote:
>>>> Hello,
>>>> i'am trying to add a time reversed computation to specfem2d. First 
>>>> I  thought it would be enough to change sign of deltat(and 
>>>> deltatcube...)  after some time iteration steps(e.g. half of 
>>>> NSTEP). But it doesn't  seem to be that easy, because it leads to a 
>>>> extremly big maximum norm  of vector field, which aborts the program.
>>>> Does anyone have an idea how this could work?
>>>> Thanks,
>>>> Jörg Buchwald
>>>> Student
>>>> University of Leipzig
>>>>
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>>>
>>
>

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