Recording Parameters of Torsional Vibrations of Turbogenerator Shafts

It is proposed that the mechanical state of turbogenerators be regularly monitored by photoelectric chronometric recording of low-frequency torsional vibrations of their shafts. The vibrations are caused by small sudden changes which are continuously occurring in the operating parameters of the turbine unit.     

Effect of the counterion behavior on the frictional-compressive properties of chondroitin sulfate solutions

Chondroitin sulfate is a major constituent of articular cartilage, which is known to affect in a decisive way the mobility and flexibility of our joints. A deviation from the physiological conditions, like e.g. a deficiency of water and salt content, in the cartilage tissue has long been suspected to be a possible trigger for rheumatoid diseases. Progresses in understanding the frictional-compressive behavior on the molecular level have been hindered due to the lack of reliable experimental data and the multitude of controlling parameters, influencing the structure and properties of cartilage tissue in its natural environment. In this paper we study the thermodynamic response of aqueous chondroitin sulfate solutions to changes in the monomer and added salt concentrations, using a recently developed field-theoretic approach beyond the mean field (MF) level of approximation. Our approach relies on the method of Gaussian equivalent representation, which has recently been shown to provide reliable thermodynamic information for polyelectrolyte solutions without and with added salt over the whole range of monomer concentrations. We compare our calculation results to experimental as well as molecular modeling data, and demonstrate that it provides useful estimates for important thermodynamic properties. Moreover, we obtain conclusive insights about the hydration effects and counterion behavior under various conditions, which show that, at the physiological salt concentration, CS solutions have optimal compressive and tribological properties. Finally, our work provides support for the possibility that a long-term deviation from the physiological conditions may trigger rheumatoid diseases.     

Minimization of basic quality indices in linear discrete systems

A method of synthesis of controllers for one-dimensional linear discrete control systems is put forward, which optimizes a transition function relative to basic quality indices such as the overshoot or the settling time. This method rests on the conditions of the finite duration of a transient process, which determines the convexity of objective functions by the parameters of a controller and systematically enables reducing the optimization problems to the standard algorithm of linear programming.Translated from Avtomatika i Telemekhanika, No. 3, 2005, pp. 65–73.Original Russian Text Copyright © 2005 by Kiselev.Deceased.This paper was recommended for publication by B.T. Polyak, a member of the Editorial Boarb     

Two types of kinetics of corrosion cracking of a high-strength steel with a martensitic structure

The authors are grateful to S. L. Namm, V. G. Khanzhin, and A. A. Petrunenkov for useful discussion, and also to V. I. Chizhikov and V. V. Savele'va for help in electron microscopic examination.     

Geometry and nature of the interfacial layer in polyimide coatings

A new approach to the quantitative evaluation of the thickness h_i and the volume fraction V_i of the interfacial layer in polyimide coatings has been developed using the model of a one-sided polymer coating as a three-phase system (a substrate, an interfacial layer and a polymer matrix) and the method of differential scanning calorimetry. The new approach is characterized by the fact that a “pure” polymer matrix is modeled with the help of free films obtained on mercury. The formulas for the calculation of the thickness and volume fraction of the interfacial layer have been proposed. The value h_i has been determined in polymer coatings of different thicknesses on aluminium foil. This parameter has been shown to be independent of the film thickness if the latter is not larger than the length of the interfacial layer. An assumption has been made about the “mechanical” origin of thick (> 1–5 μm) interfacial layers, and their relaxation character has been revealed.     

Chernobyl experience of emergency data management

The use of the Chernobyl experience in emergency data management is presented. Information technologies for the generalization of practical experience in the protection of the population after the Chernobyl accident are described. The two main components of this work are the development of the administrative information system (AIS) and the creation of the central data bank. The current state of the AIS, the data bank and the bank of models is described. Data accumulated and models are used to estimate the consequences of radiation accidents and to provide different types of prognosis. Experience of accumulated analysis data allows special software to be developed for large-scale simulation of radiation consequences of major radiation accidents and to organize practical exercises. Some examples of such activity are presented.     

More Effective Numerical Methods for Analyzing Thermomechanical Processes in the Components of Equipment in a Nuclear Power Plant

An increase in the efficiency of the finite-element algorithm for solving the problems of calculating the stress-strain state of the structural elements of a nuclear power system with a complicated three-dimensional geometry is examined. The construction of the finite-element models of such elements, which adequately reflect the structural features, makes it necessary to solve enormous systems of linear algebraic equations. For this it is suggested that iteration methods based on the method of conjugate gradients with preconditioning of the matrix on the basis of incomplete Holesski decomposition be used. Modifications of methods for constructing the preconditioning matrix are developed, the efficiency of the basic and modified algorithms is investigated for the example of a calculation of the stress-strain state of a IR-8 pipe panel. It is shown that the models which describe in detail the geometry and structural features of the objects studied make it possible in certain cases to decrease the conservatism of the normative estimates.