TY - JOUR T1 - The Wave Equation Approach to Robbin Inverse Problems for a Doubly-Connected Region: An Extension to Higher Dimensions JO - Journal of Computational Mathematics VL - 3 SP - 301 EP - 312 PY - 1989 DA - 1989/07 SN - 7 DO - http://doi.org/ UR - https://global-sci.org/intro/article_detail/jcm/9478.html KW - AB -

The spectral function $\hatμ(t)=\sum\limits_{j=1}^\infty e^{-itλ^{\frac{1}{2}}_j}$ where $\{λ_j\}^\infty_{j=1}$ are the eigenvalues of the three-dimensional Laplacian is studied for a variety of domains, where $- \infty<t<\infty$ and $i=\sqrt{-1}$. The dependence of $\hat{\mu}(t)$ on the connectivity of a domain and the impedance boundary condition (Robbin conditions) are analyzed. Particular attention is given to the spherical shell together with Robbin boundary conditions on its surface.