Coupling of numerical Green''s matrix and boundary integral equations for the elastodynamic analysis of inhomogeneous bodies on an elastic half-space

A coupled system of integral equations (of the domain and boundary types) is formulated for the elastodynamic response analysis of a locally inhomogeneous body on a homogeneous elastic half-space. The method uses the fundamental solution for homogeneous elastostatics in the inhomogeneous domain owing to the lack of a fundamental solution in inhomogeneous elastodynamics.

The integral representation of displacements in the inhomogeneous domain is formulated with the help of this elastostatic fundamental solution by considering the term induced by the inhomogeneity of materials and the acceleration term as the body force term. Then the Green's matrix is obtained numerically from this integral representation and combined with the ordinary boundary integral equations, which are valid in the exterior homogeneous half-space.

Some numerical examples show the efficiency and the versatility of this coupled method.     

On the factors influencing the dispersion of radioiodines

Radioactivities dispersed from 0.1 N sodium hydroxide solutions of 123I, 125I, or 131I were measured, and the factors influencing dispersion of radioiodines were analyzed. The radioiodines dispersed were trapped by glass fiber filters, charcoal filters, and separable paint. The factors influencing the dispersion of radioiodines are discussed in terms of the dispersal rate, which defined as the ratio of total activity of three kinds of traps in a unit time to whole activity. In order to clarify the factors influencing the dispersal rate, we carried out the experiments; on the effect of reducing agent, that of radioactive concentration of radioiodine, that of mixing the 125I solution with 131I, and that of scavenging hydrated electrons and hydroxyl radicals. It could be concluded from experimental results that the principal factors influencing dispersion of radioiodines are the number of atoms of radioiodine per volume and the energy absorbed in solution from radioiodines. In regard to the absorbed energy, we thought that the dispersion of radioiodines is influenced mainly by hydrated electron, not markedly by hydroxyl radical.     

Coloured-noise-induced transitions: Exact results for external dichotomous Markovian noise

A general method to calculate explicitly the stationary probability of nonlinear systems subjected to a special case of coloured noise is presented. For a simple model system the “phase diagram” for the various noise-induced transitions is determined.