This article analyzes the problems of spatial, temporal and phase synchronization in non-cooperative passive bistatic radar coordinate meters, which make it difficult to detect weak objects. The method of time and phase synchronization based on the estimation of the parameters of the direct wave signal and the method of detecting weak objects, which consists of a long coherent accumulation of signal parameters, are investigated. A universal algorithm is proposed, which consists of two stages: extraction of direct wave pulses and parameter estimation. Based on the estimation of parameters and waveform, an algorithm for detecting weak targets based on the generalized Fourier transform is given.

Keywords: non-cooperative passive bistatic radar, algorithm, synchronization, pulse, generalized Fourier transform

The search for orthogonal and quasi-orthogonal matrices is considered as a sequence of setting initial conditions, choosing an implementation method, filtering a set of generated sequences. It is proposed to accelerate the search for matrices by pre-fixing their structure and filtering the generated sequences using the Fourier spectrum. Fixing the structure involves using the symmetry properties of the desired matrices. Filtering allows you to exclude sequences with explicit spectrum outliers when forming blocks of symmetric matrices.

Keywords: mining of matrices, Hadamard matrices, Propus conctruction, filtering sequences

The article presents a method for calculating short-circuit currents in a DC traction network. The system of group grounding of supports, considered in the article, is equipped with an additional conductor that improves the working conditions of the entire section of the electrified railway by reducing the resistance of the short circuit loop.

Keywords: group grounding of supports, short-circuit current, electrified railway, traction network, fiber-optic communication line.group grounding of supports, short-circuit current, electrified railway, traction network, fiber-optic communication line

The main maintenance of a diversification of production as activity of subjects of managing is considered. being shown in purchase of the operating enterprises, the organizations of the new enterprises, redistribution of investments in interests of the organization and development of new production on available floor spaces. The most important organizational economic targets of a diversification of management are presented by innovative activity of the industrial enterprise.

Keywords: ideal thread, flexible homogeneous inextensible thread, tension, balance of thread balance, balance on a smooth surface, balance on a rough surface, sag arrow

The article describes the study of the behavior of the reaction vector in the contact spot of the wheel with the support base when the values of the angle of rotation of the driving wheels vary. To find the dependence of the values, a MATLAB Simulink model was created with software blocks that allow determining the behavior of the reaction vector in the contact spot of the wheel with the support base when the values of the angle of rotation of the driving wheels vary.

Keywords: controllability, mathematical model, wheeled vehicle simulation, wheel tire, wheel rotation angle, MATLAB Simulink

The paper analyzes the thermal regime of a highly functional on-board control unit in an AMg6 aluminum alloy case and compares the obtained data with the thermal regime of a unit with a highly efficient heat sink made of composite materials. The calculation of the thermal field of the block was carried out using CAD tools based on the finite element method with a thermal application in order to assess its performance under given boundary conditions. Based on a comparative analysis of various heat-removing materials of the basic supporting structure, the least heat-stressed system was chosen.

Keywords: thermal regime, highly efficient heat removal, composite materials, on-board equipment, oxygen system, finite element method, mathematical model, computer-aided design system, electrical radio product, printed circuit board

The flow that occurs during the movement of an elevator cabin in the shaft of a high-rise building from the -4th to the 58th floor is considered. The moving elevator cabin works like a piston and pushes air in front of it out of the shaft and draws air into the shaft behind it. This effect is especially significant in high-rise buildings, which are characterized by a high speed of elevator cabins movement. The STAR-CCM+ software was used as a research method. To simulate the non-stationary problem of the elevator cabin movement, the technology of sliding meshes was used. It was found that when the elevator cabin moved at a speed of 7 m/s, the maximum pressure drops formed on the surfaces of the elevator shaft amounted to 130 Pa. It was found that the maximum flow rate of air entering the elevator shaft and from the elevator shaft into the hall due to the piston effect is about 250 m3/h. This value is comparable to the flow rates formed due to natural movement of air in the elevator shaft caused by stack effect in winter and cannot be automatically excluded from consideration.

Keywords: high-rise building, numerical simulation, piston effect, stack effect, elevator shaft

To analyze such significant indicator of the locomotive industry as the value of import customs payments, the dependence of the volume of import customs payments on weight, cost, weighted average rate and dollar exchange rate is examined. Mathematical modeling was carried out on the basis of monthly data during the period from 2019 up to 2021 of the volumes of customs payments and their parameters of the Group 86 of the Customs nomenclature of EAEU FEA "Railway locomotives or tram motor cars, rolling stock and their parts; track equipment and devices for railways or tram tracks and their parts; mechanical (including electromechanical) signaling equipment of all types". The interrelations of these variables are represented by a system of simultaneous structural equations. The import substitution trend developing in Russia implies strengthening the development of national industries and, accordingly, pursuing a customs policy that implies support for domestic producers and reduction of import supplies. Thus, it is relevant to determine the impact of various factors on the amount of customs duties levied by the customs authorities on foreign economic activity (FEA) participants in operations involving the import of spare parts and other goods for the locomotive building industry to make the right strategic decisions concerning customs restrictions on imports of goods of this industry.

Keywords: locomotive building industry, mathematical modeling, linear multiple regression, multicollinearity, system of simultaneous equations, identification, structural form of the model, reduced form of the model

Nowadays, the System on Chip (SoC) industry is rapidly developing. One of the objectives of SoC developers is to provide the most efficient communication between computational units. One of the possible solutions is using Networks on Chip (NoC) of various topologies with different routing algorithms. In this paper, a configurable test environment designed for cycle-accurate NoC simulation as part of a SoC, used to provide statistics about network behavior during test process, is presented. The environment is designed to evaluate NoC performance as part of a specific SoC at the development stage, when there is a full or partial RTL description of the system. The environment configuration options, its application area, general scheme and calculated NoC performance characteristics are considered. As a conclusion, an example of using the environment to evaluate the performance of a specific NoC is described in detail.

Keywords: network on chip, system on chip, performance evaluation, verification

A set of data on potentially dangerous asteroids for the Earth is analyzed. According to descriptive statistics, a preliminary analysis and data processing is performed. The correlation between the parameters allows you to identify those that will be used to train the models. With the help of machine learning models, asteroids from the database are classified into hazardous and non-hazardous. Methods of logistic regression, k-nearest neighbors; decision tree and others are used. Using cross-validation, the best method is found, then its optimal hyperparameters are determined. The quality of the classifier model is evaluated by the metrics of completeness (Recall) and its standard deviation, as well as using the error matrix (confusion matrix) and the average absolute error in percent (MAPE). The results of analysis and modeling in Python are presented, demonstrating the high accuracy of predicting the resulting model.

Keywords: machine learning, predictive model, data analysis, imbalanced data, logistic regression, k-nearest neighbors, decision tree, random forest, support vector machine, cross-validation

This paper presents a simulation of the vibrations of a membrane in the form of a rhombus. Partial solutions of the problem of free vibrations of a membrane with different initial conditions are obtained and the natural frequencies of vibrations are found. The result obtained can be used to strengthen the structural elements of aircraft with a cellular diamond-shaped structure, as well as in the design of unmanned drones of the flying wing type.

Keywords: free vibrations of a membrane, a membrane in the shape of a rhombus, natural frequencies of vibrations

CFD modeling seems to be one of the most accessible and accurate ways to calculate the characteristics of flow processes using computational and physical-mathematical methods in solving practical problems today. In particular, it is used to determine the parameters of the indoor microclimate. This article describes the process of modeling the operation of hydraulic heated towel rails in the bathroom of a residential building and selects the optimal configuration based on the data obtained as a result of the calculation in the STAR CCM + software package.

Keywords: CFD modeling, building hot water supply, heated towel rail, heat flow, heat transfer, heat transfer, indoor climate, thermal analysis, SolidWorks, STAR CCM+

The article provides an overview of wearable devices that improve the quality of user recognition of objects of the surrounding world, reveals the process of developing an intelligent module for recognizing objects of urban infrastructure for "sound glasses" - a device designed for blind users. The functionality of the module under development, its architecture is characterized, the process and results of neural network training for object recognition are described, and an algorithm for identifying the color of traffic lights is given. The results of testing the developed software module are presented. The software module created in this work is an integral component of a fully functioning device "sound glasses", the use of which will allow people with visual disabilities to get information about events and the surrounding environment and navigate even in an unfamiliar environment.

Keywords: computer vision, neural network, smart glasses, sound glasses, visually impaired, YOLOv5, object recognition

The paper analyzes the output parameters of field-effect transistors with a contact gate (controlled junction (p-n junction or Schottky gate)) both from modern highly mobile semiconductors (such as AIIIBV, AIIBVI, etc.) and semiconductors such as Si, Ge. It is shown that when the span regions are reduced to micro- and nanoscale values and conditions for the action of strong electric field strengths arise, it is necessary to take into account the dependence of carrier mobility on this field. Comparative analyses of the obtained results with the classical known ratios are carried out.

Keywords: effective mass, drift velocity, electric field strength, mobility of charge carriers, kinetic energy, current-voltage characteristic, field-effect transistor, sub-gate drift region, threshold field of the Gann effect, saturation field strength

In a market economy, it is required to calculate foundations using methods that will satisfy the requirements of the first and second limit states with the smallest margins, in order to save money. In this study, the analysis of sediments obtained by numerical and analytical methods was carried out. Analytical calculation is presented by the method of corner points according to the model in the form of a linearly deformable half-space and by the method of layer-by-layer summation presented in the form of modified Pasternak, Winkler-Fuss, Pasternak models. The numerical method is presented by the finite element method implemented in the software systems of the PC «Lira-SAPR» and the PC «PLAXIS 3D». As a result, it was found that the minimum discrepancy between the absolute settlement according to the corner point method in comparison with the analytical method according to the Winkler-Fuss, Pasternak, modified Pasternak models is 9.04%, 9.04%, 53.38%, respectively, and in comparison with the numerical method implemented in the PC «Lira-SAPR» and PC «PLAXIS 3D» is 10.49% and 0.52%, respectively. The highest accuracy in comparison with the method of corner points was shown by analytical calculations by the method of layer-by-layer summation in the formulation of Winkler-Fuss and Pasternak, and by the numerical method of calculation performed by the PC "PLAXIS 3D".

Keywords: geotechnics, foundations, «Lira-SAPR», system «Soil», «PLAXIS 3D», foundation sediment, angular point method, slab foundation, mutual influence of foundations, numerical method, analytical method, finite element method

The paper proposes a method for calculating the interval values of the coefficients of the polynomials of the numerator and denominator of the transfer function. An algorithm is presented that describes the sequence of actions performed, which makes it possible to obtain interval coefficients for the study of both linear and nonlinear systems. An illustrative example is given, which shows the calculation of the interval values of transfer functions, both continuous and discrete systems based on the use of the Matlab system.

Keywords: control system uncertainties, robust stability, marine mobile objects, transfer function with interval coefficients

The wastewater generated by the pulp and paper industry contains diverse contaminants such as organic substances, fine suspended powders, and dissolved solids. Currently, integrated treatment technologies are employed, utilizing thin-layer settling tank modules to eliminate solid contaminants. This study presents the outcomes of a comparative analysis of the efficacy of a conventional thin-layer module with flat plates and a modified thin-layer module consisting of two levels of plates, positioned in opposing directions, facilitating the rotation of water flow within the module. Through computer simulation techniques, it is demonstrated that the modified module design can enhance the cleaning efficiency by 8-30% for wastewater flow velocities ranging from 0.0025 to 0.0125 m/s. Additionally, particle trajectories and velocity fields were obtained, which clearly illustrate the direction of the dictating flow and circulation zones within the structure.

Keywords: Wastewater, pulp and paper industry, thin-layer module, module with rotation of water flow, computer simulation of particle deposition.

The article contains an analysis of the shallow elastic spherical shell on a rectangular plan, reinforced with ribs along its contour, under the uniformly distributed load. The problem is solved numerically with the variational-difference method, considering the geometric nonlineaity and the shear deformations of the shell and the ribs. As a result, the dependencies of the critical load on the shell stiffness and the ribs stiffness are obtained.

Keywords: shallow spherical shell, ribbed shell, stability, bending stiffness, geometrical nonlinearity, variational-difference method, critical load

GRP horizontal tanks are used for wastewater treatment. This material can be used for 50 years or more, which exceeds the lifetime of reinforced concrete sewage treatment plants. However, when designing the products, it is necessary to determine whether the tank should be manufactured using the continuous winding method or the spiral-crossflow method. The main problem in selecting the manufacturing method is to determine the stability of the structure against vertical loads from the soil mass. The continuous winding method provides high circular stiffness, hence resistance to various influences, while the spiral cross winding method deteriorates circular stiffness and reduces the cost of the product. The article examines constructed GRP structures made using different methods and located at different depths. The tests are carried out to study the strength characteristics of the material on the basis of the Plant of composite materials, the ring stiffness and the modulus of elasticity are determined according to GOST R 54925-2012, to confirm the data obtained, a comprehensive calculation is performed in the Midas GTS NX software using a work model (structure + soil). The Mohr-Coulomb model was selected as a model to describe the soil, the material characteristics were set according to the data obtained from the tests. The results of surveys and calculations proved the inability to use GRP containers manufactured by the spiral cross-winding method because of low circular stiffness resulting in loss of load-bearing capacity of the structure and further ingress of soil inside the container.

Keywords: GRP gorizontal containers, continuous winding method, spiral cross winding method

The accuracy of the calculation and the required computer time significantly depend on the choice of the turbulence model. This paper analyzes three turbulence models SST, k-w SST, and RNG k-e EWT with enhancement wall treatment applied to an in-line tube bundle. The distribution of heat transfer over the beam depth is determined. Velocity profiles in cross sections along the depth of the tube bundle are obtained. As a result of numerical studies, it was shown that the agreement with the experimental data for the SST, k-w SST, and RNG k-e EWT models was 75, 32 and 10%, respectively.

Keywords: turbulence modeling, tube bundles, heat transfer, mathematical modeling

This paper is dedicated to the problem of developing parallelizing compiler for computational systems with distributed memory and approaches of solving that problem. Correseponding parallelizing program transformations are described that are developed using Optimizing parallelizing system. Described transformations automatically detect optimal data placement in distributed memory to minimize inter-node data transfers, detect points inside source program to insert directives for those transfers. Inter-node data transfer optimization is performed using special graph model connecting operators and variables inside source program. Optimizing parallelizing system includes program transformations to generate Message Passing Interface (MPI) code using affine data distribution for arrays with parameters specified using compiler pragmas. Examples of MPI code generated using these distribution methods are listed. This work is based on authors' previous works. Developing compilers for code generation onto distributed memory systems is becoming important for future central processing units with tens, hundreds of thousands of cores.

Keywords: automatic parallelization, distributed memory, program transformations, data distrubution, message passing

This paper presents the results of a study of the speed and acceleration time of a wheeled vehicle with a 4x2 manual transmission with a rear driving axle. A mathematical model of this wheeled vehicle is given. For this purpose, a design scheme of the differential transmission of a wheeled vehicle with a rear driving axle was presented, and a system of differential equations of motion of the car was also given. Simulation modeling is carried out using the MATLAB Simulink environment, which allows conducting research on the developed system based on a given mathematical model.

Keywords: wheeled vehicle, 4x2 manual transmission, rear drive axle, MATLAB Simulink, mathematical model, simulation.

The study of damage to bolted connections using numerical simulation using ANSYS requires the analysis of stress fields in Cartesian coordinates along the angle and radius of the pads. The results show in detail the formation of the bolt assembly and the position of the stress concentrations. The surface between the contact elements is characterized by contact pressure, adhesion and clearance. With the help of the obtained results, it became possible to determine the stress that caused the initiation and propagation of a crack, as well as the position of the damaged section of the bolted joint.

Keywords: bolt assembly, numerical simulation, contact simulation, damage zone, finite element, abrasion

This paper presents methods of processing handwritten biometric data. The initial data are coordinates of a position of a pen on a graphics tablet. For this, the proprietary database of handwriting samples and the open signature database SVC 2004 were used. The proprietary database includes 29 users, 754 random and 754 simple forgeries. At the stage of biometric data processing, the following methods were used – «interpolation of handwriting» (entering points at an equal distance between the initial points of the handwritten signature), the histogram approach, «pen movement speed» (the path traveled by the pen at different stages of handwriting input process). Such methods eliminate the variability of the biometric data over time and over spatial axes. As a result, we recommended a standardization approach (Z-score), discretization (one-dimensional linear interpolation and discretization with variable step based on arithmetic progression) of biometric data. The table of results presents the values of the quality of biometric features. The obtained experimental results will be useful for researchers to improve their studies in the field of biometric security systems

Keywords: handwriting, biometric data, graphic tablet, verification, authentication, standardization, discretization, interpolation, information security

The article describes the development of a virtual emulator of the polyvinyl chloride drying process. The development of the emulator is implemented using the Omegaland development environment. The characteristics and functional structure of the polyvinyl chloride drying process in a fluidized bed dryer are presented. Mathematical models of elements of simulated system are considered, algorithm of their operation is characterized. The steps of developing a virtual polyvinyl chloride drying simulator are described. The flowchart is assembled in the OmegaLand Visual Modeler modeling environment. The fluidized bed dryer module was developed in the integrated development environment of Microsoft Visual Studio in the C++ programming language. The developed dryer model was integrated into the Omegaland library. The developed dryer model was tested in the emulation mode of the polyvinyl chloride drying process.

Keywords: mathematical model, drying, polyvinyl chloride, Omegaland, emulator, virtual simulator, fluidized bed dryer