Abstract
We consider an identification (inverse) problem, where the state \({\mathsf {u}}\) is governed by a fractional elliptic equation and the unknown variable corresponds to the order \(s \in (0,1)\) of the underlying operator. We study the existence of an optimal pair \(({\bar{s}}, {{\bar{{\mathsf {u}}}}})\) and provide sufficient conditions for its local uniqueness. We develop semi-discrete and fully discrete algorithms to approximate the solutions to our identification problem and provide a convergence analysis. We present numerical illustrations that confirm and extend our theory.
Similar content being viewed by others
References
Adams, R.: Sobolev Spaces, Pure and Applied Mathematics, vol. 65. Academic Press [A Subsidiary of Harcourt Brace Jovanovich, Publishers], New York (1975)
Antil, H., Otárola, E.: A FEM for an optimal control problem of fractional powers of elliptic operators. SIAM J. Control Optim. 53(6), 3432–3456 (2015). https://doi.org/10.1137/140975061
Cabré, X., Tan, J.: Positive solutions of nonlinear problems involving the square root of the Laplacian. Adv. Math. 224(5), 2052–2093 (2010). https://doi.org/10.1016/j.aim.2010.01.025
Caffarelli, L., Silvestre, L.: An extension problem related to the fractional Laplacian. Commun. Partial Differ. Equ. 32(7–9), 1245–1260 (2007). https://doi.org/10.1080/03605300600987306
Caffarelli, L., Stinga, P.: Fractional elliptic equations, Caccioppoli estimates and regularity. Ann. Inst. H. Poincaré Anal. Non Linéaire 33(3), 767–807 (2016). https://doi.org/10.1016/j.anihpc.2015.01.004
Capella, A., Dávila, J., Dupaigne, L., Sire, Y.: Regularity of radial extremal solutions for some non-local semilinear equations. Commun. Partial Differ. Equ. 36(8), 1353–1384 (2011). https://doi.org/10.1080/03605302.2011.562954
Chen, L.: iFEM: an integrated finite element methods package in MATLAB. Technical Report, University of California at Irvine, Tech. rep. (2009)
Deckelnick, K., Hinze, M.: Convergence and error analysis of a numerical method for the identification of matrix parameters in elliptic PDEs. Inverse Probl. 28(11), 115015 (2012). https://doi.org/10.1088/0266-5611/28/11/115015
Nochetto, R., Otárola, E., Salgado, A.: A PDE approach to fractional diffusion in general domains: a priori error analysis. Found. Comput. Math. 15(3), 733–791 (2015). https://doi.org/10.1007/s10208-014-9208-x
Nochetto, R., Otárola, E., Salgado, A.: A PDE approach to space–time fractional parabolic problems. SIAM J. Numer. Anal. 54(2), 848–873 (2016). https://doi.org/10.1137/14096308X
Otárola, E.: A piecewise linear FEM for an optimal control problem of fractional operators: error analysis on curved domains. ESAIM Math. Model. Numer. Anal. 51(4), 1473–1500 (2017). https://doi.org/10.1051/m2an/2016065
Sprekels, J., Valdinoci, E.: A new type of identification problems: optimizing the fractional order in a nonlocal evolution equation. SIAM J. Control Optim. 55(1), 70–93 (2017). https://doi.org/10.1137/16M105575X
Stinga, P., Torrea, J.: Extension problem and Harnack’s inequality for some fractional operators. Commun. Partial Differ. Equ. 35(11), 2092–2122 (2010). https://doi.org/10.1080/03605301003735680
Tröltzsch, F.: Optimal Control of Partial Differential Equations, Graduate Studies in Mathematics, Theory, Methods and Applications, vol. 112. American Mathematical Society, Providence, RI (2010). https://doi.org/10.1090/gsm/112. (Translated from the 2005 German original by Jürgen Sprekels)
Author information
Authors and Affiliations
Corresponding author
Additional information
Harbir Antil has been supported in part by NSF Grant DMS-1521590. Enrique Otárola has been supported in part by CONICYT through FONDECYT Project 3160201. Abner J. Salgado has been supported in part by NSF Grants DMS-1418784 and DMS-1720213.
Rights and permissions
About this article
Cite this article
Antil, H., Otárola, E. & Salgado, A.J. Optimization with Respect to Order in a Fractional Diffusion Model: Analysis, Approximation and Algorithmic Aspects. J Sci Comput 77, 204–224 (2018). https://doi.org/10.1007/s10915-018-0703-0
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10915-018-0703-0
Keywords
- Optimal control problems
- Identification (inverse) problems
- Fractional diffusion
- Bisection algorithm
- Finite elements
- Stability
- Fully-discrete methods
- Convergence