THE INVERSE CONDUCTIVITY PROBLEM WITH ONE MEASUREMENT - STABILITY ANDESTIMATION OF SIZE

We consider the inverse problem to the refraction problem div((1+(k-1) X-D)del u) = 0 in Omega and partial derivative u/partial derivative v = g on partial derivative Omega. The inverse problem is to determine t he size and the location of an unknown object D from the boundary meas urement ho(g) = u/(partial derivative Omega). The results of this pape r are twofold: stability and estimation of size of D. We first obtain upper and lower bounds of the size of D by comparing Lambda(D)(g) with the Dirichlet data corresponding to the harmonic equation with the sa me Neumann data g. We then obtain logarithmic stability in the case of the disks. In the course of deriving the stability, we are able to co mpute a positive lower bound (independent of D) of the gradient of the solution u to the refraction problem with the Neumann data g satisfyi ng some mild conditions.