The article considers the issue of studying the deviation of geometric parameters of a curved surface and a facet surface approximating it. The approximating surface was constructed by triangulation. To obtain adequate results when approximating a surface, it is necessary that the geometric parameters of the approximated surface differ minimally from the parameters of the faceted surface. One of the most important geometric parameters of a surface is its normal at a given point. The deviation of the normals of the given and approximating surfaces significantly affects the calculation error.

Keywords: curved surface, faceted surface, normal to the surface, linear frame, tinted image, plane compartment

A numerical simulation was used to investigate heat transfer in plate-fin radiators with round fillet profiles of various depths, including 0.55 mm, 1.1 mm, and 1.5 mm. The issue of flowing air around a radiator with a mass flow rate of 10-3 to 4·10-3 кг/с and a temperature of 293 K was solved. The radiator was heated using a heater, whose temperature was set from 323 to 353 K. Changes in heat flow, pressure drop, and energy efficiency indicator were shown depending on the air mass flow, according to the calculation results. The research findings indicate that the radiator featuring round fillet profiles and a depth of 1.65 mm exhibits the highest heat flow and energy efficiency indicators, as well as the lowest pressure drop.

Keywords: radiator, cooling system, numerical modeling, computational fluid dynamics, heat transfer, heat flow, pressure drop, energy efficiency, calculation, electronics

The analysis of N.N. Pavlovsky's method for calculating the parameters of the riverbed in the branches is given. The reasons for the limitation of this method have been established. The Lagrange transform is used to find the extremum of the objective function for equations of uneven fluid motion, which makes obtaining an equivalent resistance modulus highly visual and easy to use. The results of the experiment are presented.

Keywords: calculation method, multi-node sections of rivers, resistance modulus, N.N.Pavlovsky method

This article examines the previously studied linear in factors and non-linear in parameters modular regression model containing unary module operations. Through the use of binary, ternary, ..., l-ary module operations, a generalization of modular regression was proposed for the first time. A special case of generalization is considered - regression with a multiary operation modulus. The problem of accurately estimating such a model using least absolute deviations is reduced to a mixed integer 0-1 linear programming problem. Using data on farm productivity built into the Gretl econometric package, classical linear regression and modular regression with a multivariate operation were built. The quality of approximation of the proposed modular regression turned out to be higher than the quality of the linear model.

Keywords: regression analysis, modular regression, least absolute deviations, multiary operation modulus, mixed integer 0-1 linear programming problem

In the conditions of modern economy, where optimal personnel decisions are very important for any organizations, especially in the dynamically divisive electric power industry, the issue of developing an intelligent system for making personnel decisions in the electric power industry becomes relevant. This paper analyzes the existing tools for selection of candidates for vacant positions including managerial positions and vacancies from the electric power industry. Based on the analysis and earlier research, a competency profile of managers of the electric power industry is formed. The development of the program product was conducted using various programming languages in the Visual Studio development environment. The program represents a dynamic and interactive process of managerial decision-making, where users face different scenarios to assess the formed competencies, with the output of a detailed report on their skills, which provides employers with an objective assessment of the candidate's potential for a vacant managerial position.

Keywords: electric power industry, competences, personnel, personnel, optimal personnel management decisions, intellectual system, personnel management, competence assessment, software product