Initial Dirichlet problem for half-plane diffraction: Global formulae for its generalized eigenfunctions, explicit solution by the Cagniard-de Hoop method.
Integral Equation Methods in Obstacle Elastic Scattering
Invisible obstacles
It is proved that one can choose a control function on an arbitrarilly small open subset of the boundary of an obstacle so that the total radiation from this obstacle for a fixed direction of the incident plane wave and for a fixed wave number will be as small as one wishes. The obstacle is called "invisible" in this case.