When choosing an intensification method, the assessment of thermal-hydraulic efficiency is an important criterion. In this paper, the thermal-hydraulic efficiency of the pulsating method of heat transfer intensification was assessed as applied to an in-line tube bundle. The thermohydraulic efficiency was estimated by comparing the ratio of the increase in the Nusselt number to the increase in the coefficient of friction factor in a pulsating flow compared to a stationary flow. The coefficient of friction factor was determined by numerical simulation in AnsysFluent. The results of a numerical study showed that an increase in the product of the pulsation amplitude and the Strouhal number leads to a decrease in the thermal-hydraulic efficiency at all values of the Reynolds number, while the thermal-hydraulic efficiency is higher at the minimum values of the Reynolds number.

Keywords: Reynolds analogy factor, flow pulsation, heat transfer enhancement, thermal hydraulic efficiency.

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 the work, a method was implemented that allowed estimating the parameters of a control object based on the objective function, the least squares method, and the solution to the system of nonlinear equations was the Levenberg-Marquardt method. The numerical and laboratory experiments carried out allow us to speak about the effectiveness of the proposed method.

Keywords: identification, optimization, least squares method, Levenberg-Marquardt method, differential equation

The article considers the use of collapsible road surfaces on temporary roads and develops a method for substantiating the composition of a set of collapsible road surfaces, the use of which will ensure the construction of a section of highway in the most likely conditions, such as entrances to construction sites, as wooden roads and even bridges, approaches to the bridge, detours of main roads during construction. the proposed method of substantiating the composition of a set of collapsible pavement allows you to calculate the composition of the set not only taking into account its weight and size characteristics, but also the conditions of use. The main of these conditions is the uncertainty of the length of the sections of the highway that require the use of the SRDP. In contrast to the existing ones, the proposed method allows to reduce the influence of uncertainty and obtain the composition of the kit, the use of which will ensure the construction of a section of the highway in the most likely conditions.

Keywords: highway, entrance, road surface, bridge, approach to the bridge, construction site, collapsible road surfaces, slab, road construction, method

The comparison of technological settlement values during the construction of various variants of diaphragm wall is presented. Numerical modeling of the construction of a diaphragm wall enclosure was performed in weak water-saturated clayey soils using the Plaxis 3D software package. The investigation results revealed that the technological settlement of the building foundation caused by constructing a trench-type diaphragm wall significantly exceeds the values observed in the construction of a diaphragm wall with augered piles.

Keywords: technological settlement, excavation enclosure, diaphragm wall, numerical modeling, Plaxis

The article deals with the issue of the reconstruction of the A-2 station in the context of the development of the North–South transport corridor. The relevance of the topic lies in the need to master the growing volumes of transportation from Russia to the countries of Southeast Asia and back in connection with the current reorientation of the main export cargo flow and economic ties of Russia. The analysis of the existing volumes of work of the station is carried out. To develop proposals, an analysis of the volume of work of the station was carried out, according to which there was a decline in production over the previous period. Measures are proposed for the effective development of the expected cargo flow. Statistical modeling methods, queuing systems theory and feasibility studies were used as methods. As a result, the proposals made are aimed at implementing the effective operation of the A-2 station. The reconstruction of the station makes it possible to ensure the development of increased cargo volumes and thereby receive additional income.

Keywords: relevance, transport corridor, station, goal, analysis, cargo turnover, volume of work, forecast, activities, expected effect

The assumptions of mathematical models for calculating the crack resistance of reinforced concrete structures are considered. For each of them, an analysis was carried out to determine whether they correspond to reality throughout the entire life cycle of the structure: from the hardening of the concrete mix to destruction. Based on the results of the analysis, it was proposed to use only one single calculation at the level of standards to assess the crack resistance of structures - according to the crack opening width, acrc. So, for example, at a certain value of acrc, the structure will still remain airtight (the cracks will be non-through), and if this value is exceeded, it will not. At the same time, the calculations already available in the norms for limiting permeability and the safety of reinforcement will still remain in demand. At the junction of the theory of damage accumulation and nonlinear fracture mechanics, a compressed algorithm is proposed for possibly taking into account the influence of cracks at all scale levels of the concrete structure, the key for which is the normalization of the statistical parameters of the distribution of discontinuities by diameters, lengths, openings, depths, directions, distances between discontinuities, etc.

Keywords: reinforced concrete, crack resistance, cracking moment, crack width, plasticity coefficient, damageability, non-linear fracture mechanics

The article presents the results of a study of the use of reinforcement in glued wooden elements of a circular mesh vault. The use of reinforcement in flat wooden structures has proven itself well, but the possibility of using reinforcement in large-span spatial structures still remains little explored. A number of authors presented conflicting data regarding the increase in the bearing capacity and rigidity of reinforced wooden glued elements. In the proposed work, a numerical experiment was performed to compare various options for reinforcing elements of a circular mesh vault. 10 options for external and internal reinforcement of elements with various materials were considered. As a result of the analysis of the stress distribution in the section of the elements, it was revealed that external reinforcement is a more priority method of reinforcement in terms of the stress-strain state of the element. The dependences of the deflection on the height of the section and the area of the reinforcement were determined. The most appropriate solution in terms of material consumption, economic efficiency and corrosion resistance is internal reinforcement with carbon composite reinforcement.

Keywords: Circular mesh vault, glued timber, wood reinforcement, FRP, external reinforcement, numerical stress analysis, economic efficiency of reinforcement

The article deals with the application of load-bearing and enclosing structures made of glued wood for multi-storey, including residential, buildings. Introduction. The relevance of the construction of wooden multi-storey buildings is confirmed by quite a large experience of construction abroad. Also, there is an increasing interest in this industry in Russia at present. Theoretical numerical study and technical and economic evaluation of the results. The stress-strain state and technical and economic indicators of three structural schemes of the building are analysed in the proposed work on the basis of the theoretical study: frame scheme - full frame with bearing columns, floor and roof beams; combined structural scheme - vertical bearing elements are wooden columns, glued wooden panel is used as floor and roof; frameless structural scheme - all the structural elements are made of glued wooden panels. Conclusions. As a result, the most rational and economically favourable structural solution of a multi-storey building made of glued wooden elements has been obtained.

Keywords: glued timber structures, wooden multi-storey building, structural design, economic efficiency, stress-strain state

This work is a continuation of a scientific study to determine the effectiveness of composite materials based on carbon fabric in the field of strengthening bending and compressed elements. The article is devoted to the determination of the geometric characteristics of prototypes, the description of the structure of the internal metal frame and the methodology for strengthening reinforced concrete samples. The importance of this scientific work lies in the fact that one of the most popular companies selling composite materials in Russia (“Gidrozo”) proposes to use a new technology for reinforcing reinforced concrete structures that differs from that recommended in the norms. However, according to the manufacturer's specialists, this technique not only ensures reliable adhesion and joint operation of reinforcement materials and structural concrete, but also significantly increases the efficiency of the composite material.

Keywords: steel, heavy concrete, reinforced concrete, composite material, reinforcement, carbon fiber, test, stand, beam, sample

The problem of fake diplomas of education causes alarm and concern to society. In the digital age, falsification has reached great proportions. In this regard, a mechanism for recording and confirming the authenticity of diplomas using technology is proposed. A sector-token method of accessing a blockchain record is proposed. The recording technology and the blockchain formation model are shown. The proposed technology guarantees that the diplomas are genuine, protected from forgery, belong to the specialists who received them.

Keywords: blockchain, data protection, diploma forgery, educational institution, authentication

Overview of existing methods for diagnosing faults in synchronous electric motors and methods for their detection. Classification and analysis of existing methods, their applicability in detecting faults, advantages and disadvantages. Three classes of possible faults in synchronous permanent magnet motors are considered and described: electrical faults, mechanical faults, and demagnetization. The article discusses three classes of diagnostic methods: based on the construction of a mathematical model of a real electric motor and modeling its errors, based on processing signals from sensors, and intelligent methods based on processing collected data using artificial intelligence. The following error detection methods based on modeling are considered: detection based on the model of the electrical schematic, based on the analytical model, and based on the digital simulation model. The following frequency-time analysis methods of the obtained signals from the sensors are considered: analysis using fast Fourier transform, short-time Fourier transform, wavelet transform, Hilbert-Huang transform, and Wigner-Ville distribution. The following intelligent diagnostic methods are considered: diagnosis using convolutional neural networks, recurrent neural networks, support vector machines, fuzzy logic, and sparse representation.

Keywords: Synchronous motor with permanent magnets, faults of electric motor, modeling, fast Fourier transform, wavelet transform, Hilbert-Huang transform, Wigner-Ville distribution, neural networks, fuzzy logic, support vector machine, sparse representation.

The results of studies of two-layer reinforced concrete beams with a layer of various thicknesses of high-modulus concrete of the frame structure in the compressed zone and traditional heavy concrete in the rest of the section are presented. The stress-strain state of normal cross sections along the height of the beam was estimated by the values of relative deformations at the level of stretched and compressed reinforcement using the hypothesis of flat sections and actual compression and calculated tensile deformation diagrams of concrete. The influence of the thickness of a layer of high-modulus concrete on the nature of the stress-strain state between the layers is shown. The possibility of destruction of the beam on the concrete of the compressed zone was revealed due to the abrupt decrease in the actual height of the compressed zone due to the "shooting" of a layer of high-modulus concrete with its thickness less than 0.1 h0. The dependence of the relative actual thickness of the compressed concrete, i.e. the distance from the edge fiber of the compressed concrete to the neutral axis, in the studied beams on the magnitude of the bending moment is obtained. It is established that for single-layer beams, with a difference in the elastic modulus of concrete up to 20%, the dependences of the relative actual thickness of the compressed concrete layer on the bending moment are almost identical. In the studied beams, the limiting state of which is caused by the fluidity of the reinforcement, the thickness of the compressed concrete layer was 0.37 ...0.4 with a relative moment value of 0.5, and 0.33 ...0.36 with a maximum bending moment value.

Keywords: double-layer reinforced concrete beams, normal cross-sections, nonlinear deformation model, high-modulus concrete, neutral axis coordinate

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 article discusses automatic selection of coefficients for PID controllers of quadcopter motors based on a 3D model. This selection became possible thanks to the method discussed in the article for exporting a 3D model of a quadcopter, created in the Solidworks CAD system, into the Matlab/Simulink environment, as well as with the further use of the SimMechanics library. To select the coefficients, a quadcopter control system is also implemented to the Simulink project, the signals from one sent to the motors in accordance with their physical location. The result of the article is a flight visualization of a 3D model of a quadcopter with a control system implemented in Simulink.

Keywords: solidworks, matlab, simulink, quadcopter, uav, pid, simmechanics