An assessment of the fire risks of production was performed. The volumetric concentrations of the vapor of petroleum resin corresponding to the upper and lower concentration limits of ignition are determined. The technique of experimental determination of the vapor saturation pressure of petroleum resin as a function of temperature is described. The results of an experimental study of the equilibrium pressure on temperature for a petroleum polymer resin are presented. A functional dependence of the equilibrium vapor pressure on the temperature of the medium is proposed. The interval of partial pressures and temperatures is determined in which the ignition of the process fluid is possible. The evaluation of various stages of the production of petroleum resin in terms of fire safety was made.
This article examines management decision-making in the professional selection of applicants using mathematical modeling methods. The article explores the potential of a multivariable mathematical model as the basis for a decision support system. A multivariable model is a formalized representation of an applicant as a vector of indicators, each of which is assessed on a scale and weighted according to its significance. The main proposed methods include the analytic hierarchy process, logistic regression, and multivariate statistical analysis. The use of multivariable models, analytical support methods, and modern modeling technologies not only improves the effectiveness of the admissions committee but also significantly improves the composition of applicants, which directly impacts the department's long-term effectiveness. These methods significantly improve the quality, speed, and validity of decisions in the professional selection of applicants.
Promising technologies for transporting round timber from remote areas involve, after passing through shallow water areas, forming small-sized packages into two-tiered package units without violating their integrity. The devices designed for this purpose are intended to align the ends of two-tiered package rafting units, carried out in order to increase their strength and nontaperity, which allows for a reduction in towing costs along the main part of the route. The aim of the study has been to obtain formulas for calculating the forces required to align the ends of two-tiered package rafting units formed in water and to establish the nature and degree of influence of the main determining factors on these forces. The research method has been theoretical. Analytical formulas have been obtained for calculating the forces required for aligning the ends of logs in the lower and upper packages of two-tiered package rafting units. Determining the value of a, included in the given formulas, is associated with the calculation of integrals, which is undesirable in practical calculations. It has been proven that a depends on the shape coefficient of the packages, on the ratio of their height to the diameter of the logs and on the tier in which the packages are located. Using numerical methods, the values of a have been determined for various combinations of determining factors. Based on the calculation results for the standard shape coefficients, approximating dependencies have been obtained, which make it possible to establish, in practical calculations, a and the end-cutting forces for packages of both tiers. When designing devices, the calculated force for aligning the ends of two-tiered package rafting units consists of the corresponding double forces for the upper and lower packages. The most significant factor influencing the force of alignment of the ends of the logs in a package is the ratio of its height to their diameter. An increase in this ratio in the studied range is accompanied by an increase in the considered force for packages of both tiers by 4.90–5.02 times. The package shape coefficient also significantly influences the output value. Its increase from 1.5 to 2.5 causes a decrease in the alignment force by 75–77 % for the lower packages and by 52–56 % for the upper ones. The relationship between the alignment force and the volume of the package is linear. To align the ends of logs in the upper tier packages, more force is required than in the lower ones.
The paper developed and verified a mathematical model for the operational forecasting of the dynamics of forest fires, based on a system of partial differential equations. The model includes a non-stationary heat conduction equation, convective heat transfer by air flows, and the combustion kinetics of cellulose materials, taking into account the humidity. The scientific novelty of the work lies in the adaptation of a physically grounded approach of heat engineering to the problems of modeling natural fires, which allowed to take into account the influence of meteorological factors and the properties of combustible materials. A computational algorithm based on an implicit difference scheme and the method of forward sweep is implemented. Quantitative relationships have been established: an increase in wind speed from 1 to 6 m/s leads to a 4.3-fold increase in front speed, while an increase in humidity from 5 % to 30 % reduces it by 1.8 times. Verification based on experimental data showed a discrepancy of no more than 12 %. The practical significance for the Russian Ministry of Emergency Situations is to create a tool for predicting the time it takes for a fire to reach populated areas and optimizing firefighting operations.
