The 3D inverse problem for waves with fractal and general annular bounded domain with piecewise smooth Robin boundary

This paper deals with the very interesting problem of the influence of the boundary conditions on the distribution of the eigenvalues of the negative Laplacian in R3. The spectral distribution , where {μJ}J=1∞ are the eigenvalues of the negative Laplacian −Δ3=−∑υ=13(∂/∂xυ)2 in the (x1,x2,x3)-space, is studied for small t for a variety of domains, where −∞