The paper has proposed algorithms for calculation of shock electrodynamic forces acting on the layers of multi-layer plain contacts under short-circuit conditions based on electromagnetic force density, which is calculated with the account of non-uniform electromagnetic field distribution and with simplified current density distribution. Results pertaining to calculation of forces and their comparison are given in the paper. It has been shown that magnitudes of forces calculated in accordance with simplified algorithms exceed forces with due account of non-uniform field distribution by 5 ... 25 % .

The paper considers digital filters for microprocessor protection of electric installations with number of immediate value reading n=10 and 12, and optimum parameters of low frequency filters and the considered digital filters have been also selected.

The paper shows a vital importance of electrodynamic affect account in respect of relatively small short-circuit-currents on flexible current-conducting wires of electric supply systems at long short-circuit duration. Insufficient electrodynamic stability of flexible current-conducting wires of type design has been revealed. While using simplified and numerical methods for calculation of wire dynamics optimum parameters of flexible current-conducting wires have been determined.

Investigations results pertaining to ferro-resonance and cumulative over-voltages in switch gears by means of computer modeling are given in the paper. In order to solve the problem concerning limitation of ferro-resonance and cumulative over-voltages it has been proposed to use a nonlinear resistance which is brought from the side of  low-voltage winding of the voltage transformer. The paper shows efficiency of the protection from both over-voltages in the integrated gear.

Review of internal over-voltages in distribution networks 6…10 kV and means of their limitation has been carried out. One of the most efficient remedy for reduction of over-voltage at arcing ground is resistive neutral grounding. In order to estimate an influence of a nonlinear over-voltage limiter (NOL) on over-voltage reduction at ground an experimental research of varistor characteristics with 2,4 and 3,8 kHz frequencies has been carried out.

Parameters of the NOL dynamic model have been determined. The main peculiar feature of the model is an account of m-lag time constant.

A mathematical modeling of transitional processes in distribution networks with NOL has been made.

Over-voltages in the calculative experiment at arcing ground for load diagram have accounted for 3.2 Uf, that corresponds to the results of field tests.

The paper proposes some additional conditions for high-voltage circuit-breaker selection keeping in mind coordination of the switched over-voltages and voltages induced in secondary circuits with their permissible values.

The given paper recommends to use Godounov method for description and analysis of transient processes accompanied by electric arc which can be initiated in distribution networks on the terminals of electric equipment of various voltage class.

The paper gives mathematical formation and solution of the heat-mass transfer problem when liquid metals are flowing in the channels of complicated geometry. The problem is solved with the help of numerical methods. A method of control volume is used for finite-difference approximation of transfer equations. The research results can be applied for execution of a numerical experiment while investigating heat-mass transfer in liquid-metal heat-transfer and reological media.

The paper contains results of correlation and stochastic analysis for regularities in shrinkage of the Lukoml clay and molding mass prepared on its base, and also the Gloukhov and Gloukhovetsky kaolin and their mixtures.

It has been revealed that an exponent is the most convenient approximation form of the shrinkage characteristic for the Lukoml clay and molding mass prepared on its base within significant range of moisture changes.

After products’ molding in a vacuum press a linear dependence is considered as the most convenient type of approximation within the range of moisture changes and with the main shrinkage.

One of the methods that makes it possible to increase operational efficiency of heat supply  systems is development of power-and-heat generation on the basis of boiler houses of small and average power. The paper gives main prerequisites for selection of variants and power of power-and-heat generation (cogeneration) installations on the basis of gas-piston engines which are to be used at heating boiler houses.

The paper considers Dirichle boundary problem for Laplace equation  at the top semi-plane.

Approximate representation of boundary problem of heat conduction theory is worked out on the basis of its exact solution. Uniform estimation of approximate formula error has been obtained.

Electromagnetic filtration as a perspective method of filtration and purification of liquid and gas finds its wide application in oil and chemical industry. However absence of highly-reliable model of calculation that permits unambiguously main operational parameters of electromagnetic filtration and limits its wide application. 

The operational analysis of a generating set has been carried out in view of profitability, reliability and environmental factor indices. The generalized function of usefulness describing efficiency level of the generating set has been obtained.