The paper proposes an approach based on the use of mathematical methods for modeling the behavior of the designed web application and user behavior. This approach allows an evaluation of the usability of this application. The paper discusses the models of user interfaces (UI), which are used to assess the convenience of site navigation. The possibility of using two classes of UI models is shown – structural-logical (ontological) and probabilistic. Models of the first class are used to assess the degree of comprehensibility of the proposed UI navigation on the search web resource in the accepted terms. For this, mathematically defined measures of similarity between the elements of the UI and their relationships and the elements of a hypothetical (but plausible) model of the user’s perception of the search area in a given subject area are used. In particular, the paper substantiates the possibility of using Jaccard and Levenshtein lexicographic distance metrics as such measures of similarity. Probabilistic models are based on Markov chains. With the help of these models, in the presence of reliable statistical data collected during the trial operation of a web application or its prototype, it is proposed to estimate the average number of user steps required to solve a specific problem of finding information about a subject area object. The paper provides some recommendations on the use of similarity measures to improve the usability of the UI of web applications. In addition, data on the technique for estimating the probabilities of transitions of Markov chains and semantic connections are presented. To clarify the features of the UI analysis models proposed in the article, the website of the RTU MIREA Admission Committee (https://priem.mirea.ru) is provided with a fairly simple organization that provides a search for information about admission and training at the University. The application of the approach described in the paper, along with traditional methods of testing the usability of UI, will increase the overall level of usability of applications, and thereby reduce the cost of identifying and correcting related errors.

This paper is devoted to construction of reference walking trajectories for developing pedestrian navigation algorithms for smartphones. Such trajectories can be used both for verification of classical algorithms of navigation or for application of machine learning technics. Reconstruction of closed trajectories based on data from foot-mounted inertial measurement units (IMU) is investigated. The advantages of the approach are the use of inexpensive sensors and the simplicity of the presented method. We propose algorithms for reconstruction of smooth 2D pedestrian trajectories based on measurements from a single IMU as well as on combined measurements from two IMU’s. Introduced algorithms are based on application of modified Kalman filter with an assumption of IMU having zero velocity when foot contacts the ground. In case of two measurement units, it is additionally assumed that the positions of the sensors cannot differ significantly from each other. The algorithms were tested on trajectories lasting from 1 to 10 minutes, passing indoors on horizontal surfaces. Obtained results were compared with high precision trajectories acquired with GNSS RTK receivers. Additionally, the process of inter-device time synchronization is investigated and detailed description of the experiments and used equipment is given. The dataset used for verification of proposed algorithms is freely available at: http://gartseev.ru/projects/rtj2021.

Signals with quadrature amplitude modulation (QAM) is widely used for high-speed transmission of information in many radio systems and, in particular, in digital television systems. In the receiver, which is part of the transceiver equipment of such systems, there is a block for the formation of reference oscillations and a clock synchronization block. Due to hardware instabilities and propagation conditions, phase and clock errors may occur, which cause additional errors during demodulation of the received signal, and which can significantly impair the noise immunity of the reception. The paper investigates the effect of phase and clock synchronization errors on the noise immunity of coherent reception of QAM signals. Using the methods of statistical radio engineering, the parameters of the distributions of processes in the receiver are obtained and the probability of bit error is estimated. The dependences of the probability of bit error on the magnitude of the phase error in the formation of the reference oscillations and on the relative displacement of the clock moments, as well as on the signal-to-noise ratio, are obtained. It is shown that these errors can greatly reduce the noise immunity of the reception, and with an increase in the positioning of the signals, this effect increases. If we assume that the admissible reception energy loss is 0.5 dB due to each of these errors, then the allowable phase error is from ~3° at M = 4 to ~1° at M = 64, and the allowable clock synchronization error, respectively, is from ~5% at M = 4 to ~2% at M = 64. To provide more stringent requirements for the magnitude of losses, the requirements for the indicated errors increase significantly.

The article considers the method of vibration diagnostics of onboard electronic devices based on the analysis of resonant frequencies. An algorithm for diagnosing mechanical defects of the studied blocks and nodes is presented. The structure of the complex of software tools for diagnostics automation and the results of testing the proposed method are presented. The main goal of the research is to improve the accuracy of identification of design defects of on-Board electronic devices. The transition from the analysis of the frequency response to the resonant frequencies that characterize the physical and mechanical parameters of the structure is due to greater stability and lower measurement error of this characteristic. To achieve this goal, a diagnostic model of the method has been developed that allows taking into account the spread of parameters of the electronic tool, both for the serviceable state and for the state with a defect. To estimate the permissible deviations of resonant frequencies from the nominal values, statistical simulation was performed using the Monte Carlo method. It was also possible to increase the reliability of the results of the physical experiment by determining the best position of the accelerometer in terms of the response received. The article provides a structure and description of the algorithm for searching for it. The results of approbation of the considered method on the example of the printed node of the voltage divider of the control unit of the aircraft are presented. In CAD SolidWorks, the serviceable state of the test node was modeled, for which four resonant frequencies were determined, and the state with a defect in the form of a detachment of the attachment. Analysis of the results showed a shift of three values of resonant frequencies relative to the correct state. The conducted series of 10 tests revealed the defect in all 10 cases (with the permissible error of the research result). This indicates a high degree of reliability of the data obtained, the adequacy of the diagnostic model of the method and the correctness of the applied algorithms.

Based on the existing methods of measuring the dielectric characteristics of materials, the most optimal method for performing calculations in the electrodynamic computer-aided design system is selected by the finite integration method. Based on the calculated values of the scattering matrix, the permittivity and the tangent of the dielectric loss angle of the printed polymer samples are calculated according to a given algorithm. When evaluating the accuracy of the calculation of the dielectric characteristics, validation was performed for a sample with the specified characteristics. For a sample printed using the technology of fused filament fabrication, the influence of the filling parameters on the dielectric characteristics of the printed model in the X-band of wavelengths was estimated. The description of the model implemented in the computer-aided design system is given. By processing the simulation results, approximating dependences for the permittivity and losses on the degree of filling with the dielectric are obtained. It follows from the calculated angular diagrams that the decrease in the degree of filling of the dielectric directly affects the degree of anisotropy of the polymer obtained during printing in the plane of the extruded layers. This also increases the depth of the extremes observed at angles of 0°, 90° and 180°. The presence of these extremes is directly related to the fact that the force lines of the main wave type in the waveguide are located perpendicular to the wide wall and in a situation where the volumes of air gaps between the cylinders are parallel to the force lines of tension, there is a general decrease in the dielectric constant. For a printed sample consisting of two layers of crossed cylinders, the air volumes are parallel to the lines of force with a period of ninety degrees, which is confirmed by the results obtained. An increase in the depth of the extremes with a decrease in the degree of filling is associated with a corresponding increase in the air space between the cylinders in the layer of the printed polymer.

Non-inductive (throttle-free) DC/DC converters are used in low-power and highly integrated electronic systems. A circuit analysis of the basic topologies of non-inductive DC/DC charge-pumped converters which perform typical DC-voltage conversions, i.e., lowering, raising and inverting, was carried out. The galvanic isolation between the input and output circuits of the converter was achieved even in the integrated version due to forming a time delay of the switches (Dead Time, DT), commuting a “flying” capacitor, which is transferring the charge to the storage capacitor and the load. A circuit of the DT driver was developed and its parameters, at which the through-current flow in the switch is prevented and the conditions of galvanic isolation of the input and output circuits are satisfied, were studied. The simulation was built with a popular Electronics Workbench software, widely used in training of specialists in radio electronics at higher educational institutions. The results of the study of the basic power characteristics of DC/DC conversion, such as output current and voltage, voltage transfer coefficient, efficiency, output equivalent resistance, were presented. The efficiency of conversion was estimated by varying the capacities of the “flying” and storage capacitors, the resistance of the switches in the closed state, and the frequency of switching. It is proved that the charge pumping method is simple and effective at low load currents (mA units), when both the voltage transfer coefficient from input to output and efficiency are high, and are approaching to “one”. However, with the increase of the load current, the voltage transfer coefficient and efficiency decrease, the output voltage ripples increase.

A method is proposed for recognizing pre-emergency conditions of rotary installations based on the use of the Hamming window and advanced Deep Learning techniques in retrospective analysis of the results of accounting for the factors of operation of a turbine generator, diagnostics and control under critical impacts. A program of experimental studies on the model of a turbine plant with simulation of faults and receiving vibration signals has been developed. An experiment based on the homostatic method of checking the signal with Hamming windows, in the frequency, time and modulation domains and common initial data, allows one to determine the most promising signal characteristics for identification. A method has been developed for monitoring the state of turbine generators in an automatic mode for timely notification of the CHPP personnel about the appearance of signs of pre-emergency situations, as well as about the nature of faults by the method of predicting the state of a pre-emergency situation using convolutional neural networks implemented in the form of a recurrent autoencoder. Clustering is applied and clusters are identified that correspond to the spectrograms of pre-emergency situations. The effectiveness of the use of the homostatic method in combination with correlation analysis is based on the decision-making model described in more detail in other works.

It is now customary to talk about the increasing role of high-tech projects in the formation of a digital model of the Russian economy. And the breakthrough that occurred at the turn of the century is called the information revolution. The task of developing an innovative economy in Russia is to ensure conditions under which the volume of production of science-intensive products, the share of which is extremely low, will increase. The production of these products is carried out by high-tech projects requiring financial, informational and resource support from various institutions, including the state. Today, Russia has a high level of potential for innovative development in the global economic space, however, at the moment, it does not contribute to its implementation. The aim of the scientific article is the formation of a new model of state support for the development of the industry of high-tech projects, which are the basis of the information, digital and innovative economy. The relevance of the research on the selected topic is due to the fact that in modern times there is a digital transformation of the economy of the Russian Federation (RF), which requires decisionmaking on the formation of a new approach to participation in high-tech projects programs. Within the framework of the article, the following tasks were solved: trends in the development of the innovative economy of Russia and its key problems in the framework of supporting high-tech projects were considered and recommendations were made on the formation of a new model of state support for the development of high-tech projects based on the study and borrowing of foreign experience of advanced countries of the digital economy, including the USA, Germany and Japan.

The study is devoted to the study of the effect of coagulation of dispersed phase droplets on aerosol oscillations in an acoustic resonator. The mathematical model of aerosol dynamics implements a continuous mathematical model of the dynamics of a multiphase medium, taking into account the velocity and thermal inhomogeneity of the mixture components. To describe the dynamics of the carrier medium, a two-dimensional unsteady system of Navier – Stokes equations for a compressible gas is used, written taking into account the interphase force interaction and interphase heat transfer. To describe the dynamics of the dispersed phase, a system of equations is solved for each of its fractions, including the continuity equation for the «average density» of the fraction, the equations for the conservation of the spatial components of the momentum and the equation for the conservation of thermal energy of the fraction of the dispersed phase of the gas suspension. The interphase force interaction included the Archimedes force, the force of the added masses and the force of aerodynamic drag. The heat exchange between the carrier medium - gas and each of the dispersed phase fractions was also taken into account. The mathematical model of the dynamics of a polydisperse aerosol was supplemented by a mathematical model of collisional aerosol coagulation. For the velocity components of the mixture components, uniform Dirichlet boundary conditions were specified. For the remaining functions of the dynamics of the multiphase mixture, homogeneous Neumann boundary conditions were specified. The equations were solved by the explicit McCormack method with a nonlinear correction scheme that allows obtaining a monotonic solution. As a result of numerical calculations, it was determined that a region with an increased content of coarse particles is formed in the vicinity of the oscillating piston. The coagulation process leads to a monotonic increase in the volumetric content of the fraction of coarse particles and a monotonic decrease in the volumetric content of fine particles.