Stability Estimates for an Inverse Hyperbolic Initial Boundary Value   Problem with Unknown Boundaries
  In this paper we prove stability estimates of logarithmic type for an inverse problem consisting in the determination of unknown portions of the boundary of a domain in $\mathbb{R}^n$, from a knowledge, in a finite time observation, of overdetermined boundary data for initial boundary value problem for anisotropic wave equation. 
Sergio Vessella
math.AP