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We reconsider the stability theory of boundary conditions for the wave equation from the point of view of energy techniques. We study, for the case of the homogeneous half-space, a large class of boundary conditions including the so-called absorbing conditions. We show that the results of strong stability in the sense of Kreiss, studied from the point of(More)
Loosely speaking, let us explain on a simple exemple what is a meshfree method: let us pretend that we want to analyze the properties of some function whose support is included in Ω approximated by finite elements or wavelets. Either we construct some ad hoc wavelets or splines whose support is included in Ω, or we use the whole family of splines or(More)
We here propose a numerical procedure for the reconstruction of a cavity shape in a bounded domain from ultrasounds boundary measurements. The ill posed nonlinear equation for the operator mapping the boundary of the cavity onto the trace of the solution in the external surface is solved by a modified frozen Newton method. © 2004 IMACS. Published by(More)
A generalization of Isakov's theorem ((13]) to admissible shapes that include screens with a Robin boundary condition (in which the impedance is also an unknown) is presented. We also establish a characterization that enables us to distinguish the far-eld of plane screens from others. Numerical results using a quasi-Newton method are presented.
It is known that hard planar acoustic screens generate null far-eld amplitude on the directions deened by the plane that encloses them. We proved in an earlier paper that this property actually characterizes plane screens among scatterers of any shape, and we generalized it to other boundary conditions. Furthermore it was proved that a single incident wave(More)
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