The nature of hardening produced by low-temperature tempering of cold-worked carbon steels

It was shown that the hardening of steel as a result of low temperature tempering is related to the density of dislocations produced by the foregoing heat treatment. The structural state of the steel before cold working affects the number of dislocations formed as a result of cold working. After heavy reductions, the degree of hardening produced during low-temperature tempering does not depend significantly on the structural state of the steel, but is determined by its carbon content.     

Computer-based techniques for solving problems of applied and computational mathematics with given quality characteristics

The paper is concerned with computer-based techniques for the choice and development of computational resources and their efficient use to find an approximate solution with a given accuracy in a limited processor time. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 5, pp. 33–41, September–October 2006.     

Propagation of an Electron Beam in Atmosphere at Altitudes from 15 to 100 km: Numerical Experiment

The propagation of a relativistic electron momentum in the atmosphere is investigated. The motion of electrons under the effect of the geomagnetic and electric force fields, scattering, ionization, the formation of secondary electrons, the perturbation of the atmospheric conductivity, and the distribution of electric field are numerically simulated. The previous conclusion by Neubert et al. [1] is substantiated, according to which the inclusion of the vertical geomagnetic field reduces by almost two orders of magnitude the radial collision blurring of the electron beam and increases accordingly the density of energy release and ionization during the injection from an altitude of 60 km downward. The results are given of simulation of the beam injection at an altitude of 60 km downward or horizontally in the presence of a horizontal or vertical geomagnetic field, as well as of the injection from an altitude of 15 km upward along a quasi-stationary thunderstorm electric field of 5 kV/m beyond the clouds, whose magnitude and polarity correspond to the field jumps that are observed in nature. Based on the calculation results, the degree of ionization, conductivity, and the relaxation time of these parameters in the electron beam trace are estimated. The estimates show that, in the vicinity of the beam trace, because of its polarization, there is a possibility of ten- and hundredfold investigation of the electric field, of discharges in the atmosphere, or of the attainment of the runaway threshold for background relativistic electrons. The possibility is discussed of application of a light electron accelerator for the initiation of observable optical atmospheric phenomena such as blue jets, blue starters, and red sprites.     

A statistical strength criterion for brittle materials

Based on a probabilistic model of brittle microfracture (microdamage) leading to macrofracture of materials, we propose a statistical interpretation of strength criteria, which relate start of macrofracture (manifested by macrocrack formation in tension or internal structure stability loss in compression) with attainment of a certain (critical) value of density of microdefects in the material under study. The criterion is reduced to comparative analysis of microdefect density induced by the particular loading type and its critical value, which is intricnsic to this material and is invariant to the stressed state type.