Ecological aspects of liquid radwaste confinement in the severnyi deep repository

The results of studies of the effect of low-level wastes on the ecosystem of the reservoir bed at the Severnyi site of the Mining-Chemical Works are presented. The technogenic action of the wastes is greatest on stratal liquid in the region of the injection wells. In all other sections of the site, the changes of the radiochemical, chemical, and microbiological parameters were either temporary or minimal, which shows that the effect of the wastes on the subterranean ecosystem is negligible. Microbial communities present in stratal water participate in the transformation of the macrocomponents of low-level wastes and in gas generation. The formation of an individual gas phase as a result of biogenic processes under the conditions of the repository is local and does not disrupt the site’s operating regime. The activity of denitrifying micro-organisms decreases the toxicity of the macrocomponents of the low-level wastes.     

Modeling process-induced deformations of structural elements made of composite materials

A method for estimating the strength of structural elements made of composite materials with a thermosetting matrix, which was characterized by the presence of exfoliation-like defects and process-induced deformations, was proposed. In order to determine the process-induced deformations, a mathematical model, which considered thermal and chemical deformations, heat release in the course of matrix polymerization, as well as changes in the matrix properties in transition from the superelastic to the solid state, was implemented. A modeling of the deformation of a standard blank with an interstitial exfoliation-like defect was carried out. A quantitative defect of the effect of the process-induced deformations and the initial dimensions of the defects on the load at which the defect begins to grow was made.     

Optimal diagonal scaling for infinity-norm optimization

A solution is presented for the previously unsolved diagonally scaled multivariable infinity-norm optimization problem of minimizing D(s)(A(s) + Ψ(s) X(s))D⁻¹(s)_∞ over the set of stable minimum-phase diagonal D(s) and stable X(s). This problem is of central importance in the synthesis of feedback control laws for robust stability and insensitivity in the presence of ‘structured’ plant uncertainty. The result facilitates the design of feedback controllers which optimize the ‘excess stability margin’ [3] (or, equivalently, the ‘structured singular value μ’ [4]) of diagonally perturbed feedback systems.