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.     

A multiloop generalization of the circle criterion for stability margin analysis

In order to provide a theoretical tool well suited for use in characterizing the stability margins (e.g., gain and phase margins) of multiloop feedback systems, multiloop input-output stability results generalizing the circle stability criterion are considered. Generalized conic sectors with "centers" and "radii" determined by linear dynamical operators are employed to enable an engineer to specify the stability margins which he desires as a frequency-dependent convex set of modeling errors-including nonlinearities, gain variations, and phase variations-which the system must be able to tolerate in each feedback loop without instability. The resulting stability criterion gives sufficient conditions for closed-loop stability in the presence of such frequency-dependent modeling errors, even when the modeling errors occur simultaneously in all loops; so, for example, stability is assured as loop gains and phases vary throughout a "set of nonzero measure" whose boundaries are frequency-dependent. The stability conditions yield an easily interpreted scalar measure of the amount by which a muitiloop system exceeds, or falls short of, its stability margin specifications.     

Computer simulation of coherent island growth in Ge/Si and InAs/GaAs systems

The nucleation and growth of coherent nanodimensional island arrays in the course of molecular beam epitaxy in Ge/Si and InAs/GaAs semiconductor systems have been studied using computer simulation methods. The parameters of nanoisland arrays are determined as functions of the growth conditions (substrate temperature and deposition rate). The results of calculations are compared to the available experimental data.     

Modeling the kinetics of crack development in bearing plates of adhesive-bonded laminated members

The use of the finite-element method for calculating adhesive joints of plates during their work under shear and bending conditions was substantiated within the scope of a combined theoretical and experimental investigation. The possibility of extending the models developed to the area of linear fracture mechanics for laminated metal-polymer composites is shown and experimentally confirmed. The effect of a number of mechanical characteristics of a polymer binder on the character of fracture in the region of through and surface cracks in metal-fiber-reinforced plastics is evaluated.Translated from Problemy Prochnosti, No. 7, pp. 47–52, July, 1994.     

Radiation doses to VVÉR nuclear plant staff

Translated from Atomnaya Énergiya, Vol. 67, No. 4, pp. 266–269, October, 1989.     

CACSD using the state-space L∞ theory-adesign example

The L^∞ optimal control theory is used to achieve singular value loop-shaping design objectives in a multivariable aircraft pitch-axis control design example involving an unstable nonminimum phase plant. Comparison to the frequency-weighted LQG (Linear quadratic Gaussian) design shows that the L^∞ theory easily produced a superior design having both higher bandwidth and greater stability margin, with no need for designer interaction for iterative adjustment of weights, than LQG. The design example provides a vivid illustration of how the all-pass property of the L^∞ theory enables precise shaping of closed-loop singular-value Bode plots to conform pointwise to prespecified weighting functions