Dear colleague,
The Second Invariant Imbedding/Inverse Scattering Meeting in honor of the late Bob Krueger in Washington September 8-11, 1994, was very successful. Most of us still have it fresh in mind. These meetings serve as a catalyst for the scientific development within the field of inverse scattering, using wave splitting/invariant imbedding techniques. Many of us feel that this more informal exchange of ideas is harder to create at larger, general conferences in applied mathematics.
The Washington Meeting served to assess the current state of affairs in inverse scattering as viewed from the perspective of wave field splitting and invariant imbedding ideas. It seems clear from the talks and discussions at the meeting, that there still remain a number of pressing questions and concerns in addition to some fundamental problems which are still unsolved. This is particularly true for the multidimensional formulations. It is probably fair to say that there does not currently exist a computational reconstruction algorithm, based on exact solution methods, for any of the multidimensional problems discussed in Washington. While it is important for the community to meet regularly to present current results, as in Washington, we believe that the time is now right to organize a small workshop to address the most pressing issues in multidimensional inversion techniques based on wave field splitting and invariant imbedding ideas. The workshop should probably focus on the realization of computational algorithms, although clearly theoretical results which impact on this are necessary and welcome.
We would like this to be a real workshop in the truest sense, and not just another presentation of papers by invited speakers. To accomplish this goal, we believe that the community must first identify the key problems and concerns in the development of multidimensional computational reconstruction algorithms for both time- and frequency-domain formulations. Examples of such might be:
(1) The computational regularization and subsequent propagation of the wave field and its normal derivative in the preferred spatial direction in the layer-stripping procedure.
(2) The ultimate applicability of any regularized frequency-domain method, based on exact results, in light of realistic limited and noisy data, and the subsequent possibility of incorporating such methods into "intelligent" optimization algorithms.
(3) The creation of benchmark problems and corresponding solutions to validate the computational algorithms for both the direct and inverse aspects of the problems.
Once the community forms a consensus on the focus areas, the structure of the workshop can take form. We probably want to limit the number of principal problem areas to about five. This should be a manageable number for the envisioned group of 20-25 participants. We then encourage people to form sub-groups that are responsible for the planning of each key issue (each group having at least one member of the organizing committee on it). Clearly, the success of the workshop crucially depends upon everyone's active participation and sufficient preparation well before the actual meeting.
With this letter, we cordially invite you to participate in this workshop. Since many of us are planning to participate in the ICIAM'95 in Hamburg, Germany from July 3-7, 1995, the idea is to have this workshop in Mölle, Sweden from June 29-July 1. This arrangement saves travel expenses. Travel is most conveniently done via Copenhagen. Transportation from Mölle to Hamburg by train can be done July 2. After the Hamburg meeting you can take the train back to Copenhagen and fly out of Scandinavia. More details on the transportation, see below. In order to facilitate the further planning of the sessions and to make the necessary reservations in Mölle, we need the following information before JANUARY 31, 1995:
(1) will you participate in the workshop, and if so,
(2) can you augment suggestions for the principal problem areas of focus for the workshop.
The organizing committee will put together the final list of focus problems for distribution to the participants. Further details on the structure of and preparation for the workshop will then follow. We hope to receive a fast and positive reply. We further thank you in advance for your thoughtfulness concerning the focus problems. Once again, for this to succeed, we need everyone's active participation. Any suggestions are, of course, welcome.
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TITLE OF WORKSHOP
Multidimensional inversion techniques using wave splitting and invariant imbedding
PLACE: Mölle, Sweden
DATE: June 29 - July 1, 1995
ORGANIZING COMMITTEE:
James Corones corones@sleeper.ams.ameslab.gov
Louis Fishman fishman@decst3.ams.ameslab.gov
Anders Karlsson anders@teorel.lth.se
Gerhard Kristensson gerhard@teorel.lth.se
Staffan Ström staffan@hallen.tet.kth.se
Vaughan Weston weston@math.purdue.edu
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Yours sincerely,
Lou Fishman and Gerhard Kristensson