We present a study of what may be called an intrinsic metric for a general regular Dirichlet form. For such forms we then prove a Rademacher type theorem. For strongly local forms we show existence of a maximal intrinsic metric (under a weak continuity condition) and for Dirichlet forms with an absolutely continuous jump kernel we characterize intrinsic metrics by bounds on certain integrals. We then turn to applications on spectral theory and provide for (measure perturbation of) general regular Dirichlet forms an Allegretto-Piepenbrinck type theorem, which is based on a ground state transform, and a Shnol type theorem. Our setting includes Laplacian on manifolds, on graphs and $\alpha$-stable processes.

The presented thermal impedance spectroscopy of power modules simplifies significantly the failure analysis of power modules. It enables online observation of degradation within the cooling path with detailed information about failure mechanisms. The degradation of certain layer within the power module is detected by observation of Z th parameters. Several tests results are compared with analysis of the scanning acoustic microscope.

This paper is concerned with emptyness of the essential spectrum, or equivalently compactness of the semigroup, for perturbations of self-adjoint operators that are bounded below (on an L-2-space).For perturbations by a (nonnegative) potential we obtain a simple criterion for compactness of the semigroup in terms of relative compactness of the operators of multiplication with characteristic functions of sublevel sets. In the context of Dirichlet forms, we can even characterize compactness of the semigroup for measure perturbations. Here, certain 'averages' of the measure outside of compact sets play a role.As an application we obtain compactness of semigroups for Schrodinger operators with potentials whose sublevel sets are thin at infinity. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim