We present a hybrid method to numerically solve the inverse scattering problem for shape and impedance, given the far-field pattern for one incident direction. This method combines ideas of both iterative and decomposition methods, inheriting advantages of each of them, such as getting good reconstructions and not needing a forward solver at each step. An optimization problem is presented as th...

We present a direct imaging algorithm for extended targets using far field data generated by incident plane waves. The algorithm uses a factorization of the response matrix for far field data that derives from physical considerations, moreover, a resolution based regularization. The algorithm is simple and efficient since no forward solver or iteration is needed. Efficiency and robustness of th...

We discuss efficient solutions to systems of shifted linear systems arising in computations for oscillatory hydraulic tomography (OHT). The reconstruction of hydrogeological parameters such as hydraulic conductivity and specific storage, using limited discrete measurements of pressure (head) obtained from sequential oscillatory pumping tests, leads to a nonlinear inverse problem. We tackle this...

In this paper we provide an insight into the skill representation, where skill representation is seen as an essential part of the skill assessment stage in the Computational Red Teaming process. Skill representation is demonstrated in the context of Sudoku puzzle, for which the real human skills used in Sudoku solving, along with their acquisition, are represented computationally in a cognitive...

Within the framework of constraint satisfaction problem, we propose a new scheme of cooperative parallel search. The cooperation is realized by exchanging nogoods (instantiations which can’t be extended to a solution). We associate a process with each solver and we introduce a manager of nogoods, in order to regulate exchanges of nogoods. Each solver runs the algorithm Forward-Checking with Nog...

In this paper we present a discrete adjoint approach for the optimization of unsteady, turbulent flows. While discrete adjoint methods usually rely on the use of the reverse mode of Automatic Differentiation (AD), which is difficult to apply to complex unsteady problems, our approach is based on the discrete adjoint equation directly and can be implemented efficiently with the use of a sparse f...

where | · | denotes the `1 norm, ‖·‖ denotes the `2 norm, A is a matrix, b is a vector, and μ is a scalar parameter. This problem is of the form (1) with g(z) = μ|z|, and f(z) = 12‖z− b‖ . More generally, any problem of the form (1) can be solved by FASTA, provided the user can provide function handles to f, g, A and A . The solver FASTA contains numerous enhancements of FBS to improve converge...

A fast algorithm for reconstructing the profile of random rough surfaces using electromagnetic scattering data is presented. The algorithm is based on merging a fast forward solver and an efficient optimization technique. The steepest descent fast multipole method (SDFMM) is used as the three-dimensional (3-D) fast forward solver. A rapidly convergent descent method employing a “marching-on” st...

An open problem that arises when using modern iterative linear solvers, such as the preconditioned conjugate gradient method or Generalized Minimum RESidual (GMRES) method, is how to choose the residual tolerance in the linear solver to be consistent with the tolerance on the solution error. This problem is especially acute for integrated groundwater models, which are implicitly coupled to anot...

Abstract We present a three-dimensional (3D) general-measure inversion scheme of crosswell electromagnetic (EM) data in the frequency domain with direct forward solver. In problem, we discretised EM Helmholtz equation by staggered-grid finite difference (SGFD) and solved it using Intel MKL PARDISO By applying solver, simultaneously multisource problems at given frequency. inversion, integrated ...