When erythrocytes move along a narrow capillary, they take an asymmetric shape and roll along the capillary like a tractor caterpillar (tank - treading motion). The shape of the erythrocyte is approximated by a truncated cylinder and is uniquely determined by the diameter of the erythrocyte in the capillary, the volume and surface area of the erythrocyte. Other input parameters are the speed of the erythrocyte in the capillary, the frequency of rotation of the erythrocyte membrane, the charge of the erythrocyte, and the number of closed trajectories along which the charges move. It is assumed that the negative charges located on the membrane are equal in magnitude and distributed evenly over the membrane and move along closed trajectories together with the membrane. From the last parameters, you can find the number of charges on the erythrocyte membrane. According to the Biot-Savart-Laplace law, mobile charges generate a magnetic field in the surrounding space. Using computer calculations, the distributions of the magnetic field strength were obtained both near a single erythrocyte rolling along a narrow capillary, and near a capillary along which several erythrocytes move, at various values of hematocrit. The dependence of the maximum value of the magnetic field strength near the capillary on the hematocrit is found. In particular, it was shown that at a distance from the capillary equal to 8 capillary diameters, the maximum value of the magnetic field strength increases by a factor of 1.29–1.36 (depending on direction) with increasing hematocrit from 12.27% to 18.25%.

Keywords: mathematical model, magnetic field, charge, membrane, erythrocyte, capillary, hematocrit

The article aims to reveal the essence of the application of multi-criteria decision-making methods in relation to the process of organizing construction production. An overview of multi-criteria decision-making methods is presented. The criteria for the optimal choice of the calendar plan as the main document in the design and implementation of the construction process are described. Using the example of the initial construction schedule, alternative options are proposed and calculation is carried out using multi-criteria decision-making methods to select the best one based on the specified criteria and the situation

Keywords: multi-criteria decision-making methods, calendar plan, construction process, construction organization.

The relevance of creating a chatbot for advising applicants, promoting the university brand and raising awareness about the university is considered. The basic principles of the chatbot functioning are determined. Modeling of the sequence of processes using IDEF0 and UML is performed. The article contains a description of the chatbot algorithm. Activity and state diagrams are used to visualize this algorithm. The graphical interpretation of the logic of the interaction of the system elements is performed at the IDEF3 documentation level. A physical model for storing the data necessary for consultation is presented; the purpose of the tables obtained is described. The issues of fuzzy search by keywords are considered. The article describes the error correction process using the n-gram distance metric and the Damerau-Levenshtein metric. The functioning of the chatbot in the consultation mode when searching for keywords with errors in the user's message is demonstrated.

Keywords: chatbot, dialog system, messenger, natural language processing, fuzzy search, Damerau-Levenstein distance, n-gram

The results of research of engineering solutions for ventilation of swimming pools based on mathematical modeling taking into account real thermal loads and moisture releases are presented. The analysis of air distribution options in rooms with swimming pools for various purposes – a public swimming pool, a SPA complex and a sports pool with bleachers for spectators. Based on the results obtained in the form of distribution fields of the parameters of the air environment, the necessary changes in the schemes of the organization of air exchange are revealed. If the parameters deviate from the normalized values, recommendations have been developed to improve the state of the microclimate. These temperature distributions allow us to conclude that the air temperature near the surfaces of external fences meets the requirements that ensure their safety. conclusions on the compliance of the obtained results with the required parameters of the microclimate for rooms with high relative humidity.

Keywords: Swimming pool, ventilation, heat, moisture, air distribution, microclimate, air environment, numerical modeling

The article is devoted to the development of training systems for training specialists in automation and informatization. The structure and mathematical model of a training system (TS) were developed to control skills in training these specialists (in particular, in the basics of programming). The parameters of the mathematical model are based on the representation of knowledge about the studied objects and processes in the field of development of automated information systems, which allows using TS to automatically generate and evaluate small practical tasks for students. A prototype of TS software in the form of a web application has been developed. In a practical aspect, the use of TS in the educational process in the disciplines in the field of programming will reduce the proportion of labor-intensive work of the teacher in compiling and checking assignments.

Keywords: information technologies in education, training system, control of knowledge and skills, high-level programming languages

The article is devoted to the issue of increasing the efficiency of ventilation systems through the use of a new type of air ducts. The main advantage of microperforated textile air ducts is the possibility of supplying fresh air with laminar micro jets to the human breathing zone. The need to adapt the existing methods for calculating the main parameters of jets for the laminar regime is noted. The article presents the results on the development of a mathematical model of a stationary boundary layer for the numerical calculation of the movement and heat and mass transfer of air in a laminar microjet. A discrete analog of the generalized differential equation is derived, on the basis of which a software package is developed that allows one to determine the main parameters of laminar microjets. Verification of the developed software package was carried out, the discrepancy with the known engineering method was less than 3%.

Keywords: mathematical modeling, air exchange, microperforated textile air duct, microperforation, laminar jet, control-volume method, round jet, micro jet

The issues of developing a project for strengthening the building structures of a cable overpass after an emergency (accident) are discussed. On a real example, a description of the accident is given, the performance of work on the ghost of structures to the standard state is illustrated. The article was written on the basis of the completed research work No. 18-26.

Keywords: building structures, safety, cable trestle, emergency response, technical expertise, buildings and structures, metal structures, reinforcement project

The subject of the study is processes related to the construction of strip-shell foundations. The scope of the study is the construction of the base under the shell, providing a curvilinear contour of the structure. Traditionally, the foundation structure is placed in undisturbed soil, which, due to its physical and mechanical characteristics, can limit the scope of application of such foundations. Using the Harrington desirability function, the authors evaluated six models of soil masses with different physical and mechanical as well as technological properties. As a result of the studies, the suggested options were rated “satisfactory” or lower. In this regard, it is required to improve both the quality of the base under the shell and the technology for the construction of such foundations by using cost-efficient prefabricated soil-cement blocks.

Keywords: Buildings, strength, construction industry, foundation, construction technology

The analysis of the foundations of modern cryptographic systems is carried out. Problems of classical cryptography arising in the development of quantum computers are considered. Considered are cryptographic protocols of quantum key distribution, their advantages and disadvantages. The analysis of stands for simulation of quantum key distribution available on the market is carried out. The rationale for the need to develop a training system has been made. The authors have developed a system for modeling and demonstrating quantum cryptographic protocols BB84, B92 and BB84 (4 + 2), intended for a detailed study of the principles of quantum cryptographic protocols in dynamics. The system provides the process of work both in text and graphic form. The developed system fully meets the needs of teaching students modern quantum information security technologies.

Keywords: information security; encryption; quantum cryptography; modeling; education system

As part of the development of the stages of pre-project and design preparation, a set of procedures is carried out, starting with planning further stages of the implementation of a construction project, ending with obtaining a construction permit. The article describes the main provisions of the methodology for choosing rational organizational and technological solutions at the stages of pre-project and design preparation of an object for construction, and also presents the results of its implementation in construction practice. The methodology defines the main procedures at the stages of pre-project and design preparation of facilities for construction; factors influencing the duration of the procedures at the stages of pre-project and design preparation of facilities for construction. On the basis of the methodology for choosing rational organizational and technological solutions at the stages of pre-project and design preparation for the construction of an object, organizational and managerial models for passing the stages with determining the duration of procedures, taking into account the influence of factors, have been developed. The proposed methodology, used in the practice of the organization, made it possible to take into account the influence of factors on the duration of the stages of pre-design and design preparation of the above facilities for construction, thereby reducing it.

Keywords: technical customer, developer, stages of pre-design and design preparation of facilities for construction, organizational and technological solutions

In the modern world, the number of different complex technical systems is only increasing every year, and any system incorporates or uses a third-party communication system. Disruption of the communication system and its elements functioning can lead to a situation where a complex technical system cannot realize its functions. It is required to ensure the guaranteed functioning of the communication system and its elements. One of the ways to ensure the stable operation of complex technical systems is the implementation of the control function by the control system, while in the process of system operation it is necessary to take into account not the characteristics and parameters of individual elements that describe their operation, but the ability of the system to perform tasks and functions. The paper proposes an approach to describing the functioning of a communication system through the formation of the system functioning profile, which is a set of matrices, which is used in the control system.

Keywords: functional stability, criticality, communication system, control system, complex technical system, functions, tasks, profile, regulations

It is reported that recently, in many sectors of human activity, there has been an increasing interest in involving chatbots in company, organization or firm websites and in various applications to provide necessary assistance. This article deals with the current definitions of a chatbot and artificial intelligence. A chatbot is a computer program that imitates human speech using artificial intelligence. Artificial intelligence is a science and technology based on such disciplines as computer science, biology, psychology, linguistics, mathematics, and engineering. In the educational field, chatbots are useful for providing guidance and information about courses, admission processes and procedures, academic programs and academic services. However, these virtual assistants have limited mechanisms that could help the teaching and learning process. Attention is drawn to the fact that these mechanisms should be beneficial to all people involved. For this reason, the Voronezh State Industrial and Humanitarian College (GBPOU VO «VGPGK») was identified as the subject area in the development of a chatbot in the social network "VKontakte" for the page of an educational organization.The article considers the possibilities of using chatbots in the social network "VKontakte" for an educational organization focused on students and their parents. The article gives information about the development of the client part of the chatbot, namely the possibility of launching an electronic assistant using the page of the social network, the description of the data storage system for the chatbot and the server part. It is specially noted the variants of solutions for realization of a chatbot and the functioning of a chatbot.

Keywords: chatbot, website, server, client part, applications, social network, "VKontakte", mobile devices, artificial intelligence, computer program, information, educational sphere, message, training, data storage, electronic assistant

The work is devoted to the problems of protecting the document management system of public administration bodies. The aim of the work is to build a simulation model of the implementation of a targeted computer attack, taking into account the simultaneous (occurring with a slight delay) response of the security tools of the document management system. For modeling, it is proposed to use the apparatus of Petri-Markov networks, combining the representation of the change of states of the attacked system in the form of Markov (semi-Markov) processes and the expressive capabilities of Petri nets to describe the interaction of processes. The constructed model reflects both the specifics of attacks with increased user privileges, and the features of document processing processes, as well as the mechanisms used to counteract unauthorized access. Computational experiments conducted using the constructed simulation model allow us to assess possible risks and make a decision on choosing the most effective system of protection against the considered type of attacks.

Keywords: electronic document management system, computer attack, simulation modeling, Petri-Markov network

The most significant advantage of composite structures compared to structures made of traditional materials is the ability to control the characteristics of the structure in order to obtain an optimal design. In the general case, the initial physical characteristics of the material of the composite structure are random variables. Consequently, the required quantities (stresses, strains, critical loads, etc.) are also random variables. The problem of statistical modeling of a composite structure is ultimately reduced to the problem of transforming random variables. To solve this problem, the Monte Carlo method is used. The object of study is a multi-walled plate under the action of compressive loads. The purpose of this work is to construct point estimates of the coefficients of both general and local stability for a multi-walled plate, as well as to test statistical hypotheses about the equality of the stability coefficients to their theoretical values. The initial parameters are the elastic moduli in the longitudinal and transverse directions, as well as the shear modulus of the construction material. The following were used as output values: sample mean, standard deviation, skewness and kurtosis coefficients. All calculations were carried out in the environment of the MAXIMA package. It is shown that the distribution of the overall stability coefficient practically does not differ from the normal distribution. The coefficient of local stability has a slight positive asymmetry and a steeper peak compared to the normal curve. The results obtained allow us to conclude that the spread of the elastic characteristics of the material does not significantly affect the coefficients of the general and local stability of the multi-walled plate.

Keywords: statistical modeling, statistical hypothesis, multiwall plate, stability, critical load, composite material

The article is devoted to the use of renewable energy sources, namely geothermal energy for home heating. Methods of installation, advantages and disadvantages of geothermal heating are investigated. A comparative analysis of the cost of 1 MJ of heat received from various energy sources was carried out, and the efficiency of using heat pumps for heating buildings was proved. It was noted that in connection with the global problem of greenhouse gas emissions, this decision is relevant and paramount for achieving hydrocarbon neutrality. The introduction of geothermal heating methods can be a huge step towards green energy.

Keywords: system, temperature, geothermal heating, heat pump, compressor, evaporator, condenser, carbon footprint, ecology, green energy