This article examines the security of currently popular corporate instant messaging applications (messengers). A comparative analysis of the security of some solutions for corporate use has been carried out. The main result of the review is the conclusions about the advantages and disadvantages of the considered systems, which can be used by organizations to choose the appropriate solution.

Keywords: Information security, corporate messenger, messaging, internal communications, instant messaging systems, end-to-end encryption

The development of methods for calculating structures made of ultra high-performance steel fiber-reinforced concrete (UHPC) in terms of strength and deformations is an important step towards the introduction of this innovative material into the practice of design and construction. This paper presents the results of finite element modeling of the operation of UHPC I-beam in the area of action of shear forces. The SMM model integrated in the OpenSees framework application is used for the walls of beams under conditions of flat stress. The authors have added new classes of materials that implement the averaged deformation laws of UHPC (with and without fiber) and the reinforcement placed in it. The calculations showed good convergence with the authors' own test results of the UHPC I-beams, as well as with the results of experiments by other researchers.

Keywords: shear strength, shear force, ultra high-performance steel fiber-reinforced concrete, I-shaped beams, OpenSees

The paper provides a brief overview of publications on the application of mathematical modeling methods in the study of the patterns of functioning of hydroelectric power plants (HPPs). In particular, the following are considered: mathematical models of the total minimum water consumption for a cascade hydropower system in China; a mathematical model of hydropower plants; a mathematical model of two small hydroelectric power plants operating in tandem; accurate modeling of hydraulic transient characteristics in a complex drainage system. The task of filling in the gaps in the data concerning the operation of hydroelectric power plants is formulated. The approach to its solution is proposed to be based on the use of the method described in previous publications by one of the authors and based on the use of regression analysis apparatus. The specific task of filling in data gaps for a hydroelectric unit of one of the Siberian hydroelectric power plants has been solved. The following factors are used: active and reactive power of the electric generator, voltage, current and temperature of the stator iron, rotor current, air cooler hot air temperature.

Keywords: hydroelectric power plant, electric generator, data gaps, predictive analytics, regression model, adequacy criteria

Occupational safety is one of the important aspects of the organization of work in production. Domestic machines and units used in the food industry do not yet allow to exclude the impact of harmful and dangerous production factors, to make the work of employees safe. In this context, it is important to study active and passive methods of noise and vibration suppression, their effectiveness in ensuring normalized working conditions of workers on the example of a specific production. Existing research, as a rule, focuses on one criterion when choosing protection methods. However, an integrated approach is advisable in solving this problem. The purpose of this study was to choose a rational method of protecting personnel from the effects of noise and vibration based on the economic justification of effective technical solutions. The obtained research results make it possible to take into account the criteria for evaluating the validity and acceptability of choosing a particular protection method, including from the standpoint of technical and economic calculation, when designing a security system. The above study showed the expediency of import substitution in the food and beverage industry, as well as the correlation between the introduced protection systems and an increase in the level of safety. The given algorithm of the feasibility study has the properties of scale and generality. It can be successfully implemented when choosing methods of protection from the effects of other harmful production factors found in various industries.

Keywords: acoustic factor, protection methods, active and passive methods, economic justification, sound pressure levels, experimental data

Digital twins of railway stations are necessary for planning work and taking the most effective management actions. An important factor is the compliance of the planned time costs with the actual ones. One of the tasks that are difficult to formalize at railway stations is the process of holding the rolling stock. This is due to the fact that the holding time depends on the human factor and the holding rolling stock. To create an automated station controlled by a digital twin, it is necessary to develop an automated holding system. One of the tasks in developing such a system is the problem of device location. This problem can be formulated as follows: it is necessary to place the minimum allowable number of holding devices in the controlled area in such a way that reliable holding is provided for any configuration of the rolling stock. As a tool for solving this problem, the most effective will be the use of methods of genetic algorithms. In this article, the authors consider the relevance of this study and the relevance of automating the holding of rolling stock.

Keywords: digital railway station, automation, brake shoes, UTS-380, DUZS, traffic safety.

In this paper, we investigate the possibility of applying the theory of Monty Hall's paradox in tasks that require the need for an optimal choice of a strategy for developing the innovative potential of an enterprise. The article provides recommendations for taking into account and constructive use of the effects that affect the involved experts, in particular, the Condorcet principle and paradox. The paper explores the limits of applicability of the Monty Hall paradox theory. Its applicability is determined, together with considerations about the profitability of changing the initial choice in problems with the so-called "random intelligence".

Keywords: decision support systems, mathematical modeling, expert evaluation, Monty Hall's paradox, project management, collective assessment, Condorcet's paradox, enterprise management, assessment of enterprise characteristics, innovative potential of an enterpris

The reliability of assessing the amount of accumulated waste in the context of an imperfect scientific and methodological base for standardizing MSW, in the absence of generally accepted calculation methods, is not high enough. The possibility of using cluster analysis in the formation of a statistical sample of objects of a stationary trade network in setting standards for the accumulation of municipal solid waste is shown. A methodology for the formation of a representative statistical sample of objects of a stationary trading network has been developed when setting standards for the accumulation of solid municipal waste based on cluster analysis.

Keywords: waste accumulation, municipal solid waste, MSW generation standard, stationary trade network object, cluster analysis, representative sample

Effective reinforcement of the coating beam, by means of the construction of a framing frame around it, implies a reasonable choice of a construction from a range of rolled metal. The frame creates a single system with the coating beam by means of tension devices, the change of forces in which provides state control. In the article, a comparative analysis of moments in a frame made of an I-beam and a special steel channel, as having potentially equal performance characteristics, is proposed for a comparative study. The research was carried out on the basis of numerical modeling by the finite element method using the Etabs software product. The result of the experiment was the transverse forces and moments determined in the newly formed system – the coating beam plus the frame – from the applied loads and the percentage of reinforcement of the beam when taking into account the frame. The array of numbers obtained as a result of the numerical experiment was processed by digital mathematical analysis.

Keywords: reinforced concrete beam, I-beam reinforcement, channel reinforcement, moment, percentage of reinforcement, load, numerical method, mathematical model, comparison of results, Etabs and wxMaxima software packages

The article presents the results of experimental studies of crack resistance of inclined cross sections of I-shaped beams using basalt fibre reinforced bars as a transverse reinforcement . The data of previously conducted experiments were studied and the test of own samples was carried out. The beams had the same geometric characteristics and differed from each other in the angle of inclination of the transverse reinforcement, the percentage of transverse reinforcement and the shear span to depth ratio. The influence of variable parameters on the load of formation of inclined cracks and the width of their opening is analyzed. In most cases, the width of the opening of inclined cracks does not exceed the permissible values established by the codes of different countries. The exceptions were mainly samples with the lowest percentage of transverse reinforcement.

Keywords: crack resistance, I-shaped beams, transverse reinforcement, inclined cross sections, shear span, basalt fibre reinforced bars, inclined cracks

This article presents one of the methods for analyzing the chirality coefficient of a medium depending on such parameters as concentration n, frequency f, dielectric constants of both the container material, the medium itself, and left- and right-handed spirals distributed in this material. As a result of this work, the frequency characteristics of the chirality coefficient were obtained at various concentrations of the container trace elements.

Keywords: chiral medium, Telledzhene element, chirality coefficient, dielectric constant of the medium, magnetic permeability of the medium, spiral structure, metamaterial substrate, bulk concentration, metamaterial, spiral inclusions

the article analyzes the economic instruments used by states in domestic and foreign policy from the point of view of identifying the existing coercive mechanisms in modern social practices. The study revealed how states use economic instruments as the preferred means of geopolitical struggle. In addition, the work separately reflects the fact that States should preserve the right to an original socio-economic model of development. We should also not forget about the negative consequences of unilateral coercive measures. Using the method of cognitive modeling and constructing cognitive maps, the authors identify the connections in the analyzed social practices from the perspective of studying the means of geo-economic pressure.

Keywords: cyberwarfare, cyberattacks, cybersecurity risks, communication networks, transport systems, tactical, operational and strategic initiatives

The paper considers mathematical models obtained on the basis of experimental studies of electrical sheet steel. The models reflect the error in determining the main magnetization curve of electrical steel. The magnetic properties are determined in the center and at the edge of the cut of sheet samples with a size of 150 × 150 mm, made by cutting with guillotine shears and laser cutting. The choice of scale factors for calculating the main magnetization curve with an error of ± 5% according to the measured Weber-ampere characteristic has been substantiated. The study was carried out using a device for express control of the magnetic characteristics of electrical sheet steel. The main curve of magnetization of the sample material from sheet electrical steel was determined in an alternating magnetic field with a frequency of 50 Hz, along the direction of rolling. Investigated samples of isotropic sheet electrical steel grade 2212.

Keywords: mathematical model, electrical steel, magnetic properties, magnetization curve

The article deals with the difference model of coordination of general and private interests in the distribution of resources in marketing networks. The dynamics of a managed system describes the interaction of members of the target audience (base agents), leading to a change in their opinions (spending on the purchase of goods and services of firms competing in a certain market). The gain of each firm includes two components: the total opinion of the base agents, taking into account marketing costs (the common interest for all agents of influence) and the return on investment in some private activity. The Coordinating Center determines the marketing budgets of the firms and maximizes the total opinion of the base agents, taking into account the resources allocated to the firms. The total discounted income of the Center and the agents of influence are found. The results are analyzed and the optimal allocation of resources is concluded.

Keywords: models of coordination of public and private interests, simulation, modeling, marketing, resource allocation, budget, private activity

The article discusses an optical vector analyzer with high resolution and high accuracy based on optical double-sideband modulation and stimulated Brillouin scattering. A model of an optical vector analyzer is presented.

Keywords: optical vector analyzer, double-sideband modulation, stimulated Brillouin scattering, fiber Bragg grating with phase shift, simulation, Optisystem

a study of a ventilation system with a local recirculating diffuser was carried out. A three-dimensional model of the office space has been built. Using the STAR-CCM + hydrodynamic computing complex, a numerical simulation of the ventilation system has been performed. The calculation results are analyzed, the advantages of the investigated system are given.

Keywords: ventilation systems, local recirculating diffuser, indoor air quality, energy saving, numerical simulation, STAR-CCM +