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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.

The article deals with the issues of synthesis and analysis of information-measuring and control systems of quadrocopters. The main sensors and modules used to determine the parameters of the coordinates of quadrocopters are given. The speed-controlled electric drives used for control and the features of their choice are considered. The coordinate systems (fixed and mobile) and the kinematic scheme are given, according to which a system of differential equations is presented. The system describes the dynamics of the quadrocopter movement and takes into account the expected smooth movement of the quadrocopter with small roll and pitch angles. A functional scheme and a mathematical model of the information-measuring and control system of the quadrocopter in the form of a block diagram are developed taking into account the influence of delays in the receipt of information from the sensors of the quadrocopter parameters. A special feature of this work is to take into account the specific characteristics of the elements: adjustable electric drives (both direct and alternating current), parameter sensors (barometers, accelerometers, rangefinders, etc.). The paper studies an illustrative algorithm for the operation of the informationmeasuring and control system of the quadcopter. The type and parameters of the controllers of the quadrocopter control systems are determined. Special attention is paid to the settings for the control contours at the corresponding coordinates. The influence of the controllers of the coordinate control systems of the information-measuring and control systems of the quadrocopter on the effects of the interaction of coordinates is considered. The simulation results are presented. The optimal number of control loops for the coordinates of the information-measuring and control systems of the quadrocopter and the optimal type of settings for obtaining smooth transients (without overshoot) and for excluding the interaction of coordinates on quality indicators are determined.

The quality of service (QoS) in networking is the process of managing network resources to reduce packet loss and to lower network jitter and latency. QoS has been widely used in traditional network and can also be implemented in the 5G standard based on a software-defined network (SDN). A traditional network carries several challenges, such as vendor dependency, the complexity of managing a large network, dynamically changing forwarding policies, and more. Software-defined networking is a new networking strategy designed to address the challenges of a traditional IP network, such as high levels of complexity and inability to adapt to the new quality of service requirements in a timely manner. The fundamental idea behind SDNs compared to the conventional networking paradigm is the creation of horizontally integrated systems through the separation of the control and the data plane while providing an increasingly sophisticated set of abstractions. Recently, various SDN-enabled QoS frameworks have emerged that offer many possibilities for network reconfiguration and high-level definition of policies. QoS requirements for 5G networks have been defined on the basis of three main categories of use cases: extreme mobile broadband (xMBB), massive machine type communications (mMTC) IoT/M2M devices, and highly reliable М2М-communication (ultra-reliable machine-type communications – uMTC). This paper analyzes and surveys the QoS based on the openflow protocol method and QoS based on open-source SDN controllers method in 5G network. In addition, we discuss various architectural issues of open-source SDN controllers network and examine their impact on the QoS. Furthermore, we outline the characteristics of the QoS parameters such as latency, availability, reliability, jitter, and bandwidth in the 5G network. Finally, the article discusses and compares parameters of the QoS in 5G determined by world’s leaders in 5G technology.

One of the main directions in the development of optical communication systems is associated with the use of optical fiber (ОF) for data reception and transmission. Therefore, manufacturers began to pay special attention to the creation of new brands of OF, improving their optical and operational characteristics. This makes it possible to improve existing optical fiber components that use OF as an active medium. The most widely used are two-wavelength 1 × 2 WDM multiplexers/demultiplexers designed to separate and combine optical carriers with wavelengths of 1310 and 1550 nm, corresponding to the second and third transparency windows of quartz OF. It should be noted that multiplexers and demultiplexers are the same optical devices, which are spectrally selective splitters. Such devices are distinguished by a sufficiently high level of optical characteristics at a relatively low cost of products. However, an analysis of the multiplexers produced in recent years shows that the characteristics of these devices do not sufficiently correspond to the set of modern requirements imposed by most system developers, in particular on permissible values of external influencing factors, insertion loss and the value of optical isolation of channels. Therefore, the development and research of WDM multiplexers with improved optical characteristics is relevant. One of the possible ways of optimizing such devices using new types of OF with resistance to bending losses, of which WDM multiplexers could be made. In this paper, we consider the possibilities of realizing fused single-mode multiplexers/demultiplexers based on combined fiber structures. The technology and equipment for the manufacture of these devices are presented. The optical characteristics of experimental samples of WDM multiplexers are investigated. The results of testing for the effect of temperature are given.

The paper presents an analytical review of the application of biometric recognition systems in relation to facial image identification technologies. The classification of biometric systems is presented. The trends of technological progress in the field of biometrics and facial recognition capabilities are considered. It is determined that in 2020 there is a trend of transition from the use of biometric recognition technologies in traditional state security systems to the sphere of commercial and user applications. The process of «linking» encryption keys and passwords with the biometric parameters of the data subject is described. It is proposed that a biometric feature and a biometrics parameter mean a certain value that has a physical meaning that characterizes the subject itself. The possibility of using circular neighborhood and bilinear interpolation of pixel intensity values in biometrics is also presented. This will make it possible to build a local binary template. In order to solve the problem of identification of persons, it is advisable to investigate the essence of biometric systems in the technologies of identification of persons, their types, identifying the shortcomings of each of them, on the basis of which to present the directions of elimination and search for the most reliable technologies. The essence of the use of biometric systems in the technologies of identification of persons is, for example, that the user can provide the bank or other counterparty with evidence that it is he who wants to use the services on his accounts. At the same time, the demand has increased for contactless biometric solutions. These technologies are implemented in order to conduct additional biometric verification of users. This allows to minimize possible fraud or violation of the internal rules of the service, for example, the transfer of accounts of some registered users to others.

Testing of electronic devices is an integral part of the technological process of any manufacturer of such equipment. In this case, an electronic device is understood as an energy-intensive unit such as a mobile phone, data center or spacecraft. One of the key stages of testing is to identify the effect of electric fields on various electronic components of the device. This stage often requires making a mock-up of some part of an unfinished device in order to fix interference with special equipment. This requires time, financial and human resource costs. In order to reduce these costs in the modern world, the use of mathematical modeling tools for testing noise immunity and electromagnetic compatibility is becoming popular. In this paper, it is proposed to use an algorithm for visualizing electric fields in three-dimensional space and time. The algorithm is easily embedded into applications as a component of a mathematical modeling system. The work considered three ways of visualizing the electric field strength: starting from a simple setting of points in space, on the basis of which the electric field will be built, around the source of electric field radiation, to the use of algorithms that make it possible to arrange points equidistantly based on a given number of points in space for the formation of an electric field. The performance and visual implications of these methods were analyzed. The proposed methodology will be useful to the developer community as an embedded solution for point visualization of the electric field in any project in any algorithmic language with the ability to animate in time.

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.

The paper shows the approach and the result of taking into account the mutual influence of on-board subsystems of a complex technical object along the DC power supply circuits. Technical objects are understood as a mobile, energy-intensive vehicle, such as an aircraft, a surface or submarine vessel, or a railway locomotive with strong magnetic fields. The aim of the work is to create a simple and intuitive tool for mathematical modeling of the magnetic field vector at an arbitrarily specified observation point. The task is being solved in order to improve the accuracy of magnetic measurements on board, in particular, in navigation problems. On-board DC networks are considered, to which the approach of mathematical modeling is applied. The disadvantages of commercial programs of a similar purpose are noted. The binding of the objects under consideration to the general coordinate system is described. An analytical algorithm for calculating the magnetic field vector from the on-board cable network with a pronounced 3D trajectory is shown. Examples of visualization of the simulation results are given. An algorithm for calculating the induction vector based on the Biot-Savard law is considered. The algorithm for the analytical solution of the problem is described in detail. A specific power cable of the on-board network is considered. The cable is given by a set of straight conductors with current. The ways of future improvement of the created product with the transition from one observation point to the field map in a given three-dimensional zone of arbitrary position, volume and orientation are outlined. The obtained result is considered as an element of the procedure for achieving electromagnetic compatibility of energy-intensive and highly sensitive subsystems of a modern complex technical object.

Current trends in the design of electronic systems is the use of embedded systems based on systems on a chip (System-on-Chip (SoC)) or (VLSI SoC). The paper discusses the design features of electronic systems on a chip using the SystemC design and verification language. For the joint design and simulation of digital systems hardware and software, seven modeling levels are presented and discussed: executable specification, disabled functional model, temporary functional model, transaction-level model, behavioral hardware model, accurate hardware model, register transfer model. The SystemC design methodology with functional verification is presented, which reduces development time.The architecture of the SystemC language and its main components are shown. The expansion of SystemC–AMS for analog and mixed analog-digital signals and its use cases in the design of electronic systems are considered. Computing models are discussed: temporary data stream (TDF), linear signal stream (LSF) and electric linear networks (ELN). The architecture of the SystemC–AMS language standard is shown and examples of its application are given. It is shown that the design languages SystemC and SystemC–AMS are widely used by leading developers of computer-aided design systems for electronic devices.

The paper considers the algorithmic possibility of the image rejection method. The main resulting characteristics of circuits implementing the above method are presented. The simulation model allows estimating the selectivity coefficient as a function of the phase and amplitude imbalance of the circuit branches. Mathematical and circuit simulations were conducted. The results of different modeling methods coincide, and the simulation results verify the possibility of implementing the image rejection method. On the basis of this model it is possible to provide a high level (at least 40 dB) of image rejection by amplitude and phase circuit imbalance compensation. The dependence of the noise level at the output of the image rejection circuit as a function of the circuit elements frequency characteristics is given. The results of this work could be used for further practical implementation of above mentioned method at the stage of selecting elements based on an analysis of their characteristics. The simulation model could be used to select required radioelements and to estimate image rejection level. It is possible to estimate the level of image channel suppression, the noise level and the signal-to-noise ratio at the output of the image rejection circuit by using the above mentioned mathematical models and characteristics of the selected elements for practical implementation of the circuit. The effect of the broadband phase shifters on the noise level is considered with the implementation of the above method as an example. It was shown that ensuring a high level of selectivity in order to minimize the noise level of the image channel is advisable only up to some values (about 25 dB). Further improvement of selectivity, for example, by minimizing the phase and amplitude balances, or mutual compensation of the mixer and phase shifter branch imbalances are necessary, if there are requirements for increasing the signal-to-noise ratio. It is shown that it is possible to ensure selectivity of up to 25 dB and a noise level reduction of 2.5-3 dB if the amplitude imbalance of the circuit is up to 1 dB, and the phase imbalance is up to 5 deg. in the required frequency band.

The paper analyzes the condition of additivity of the information and reference kiosk, which allows designing a static kiosk, which is essentially a set of pages organized in order to provide users with reliable information in various fields of knowledge and practice, with additive properties. The condition of additivity is analyzed based on the loading time of the pages of the informational kiosk is implemented on the basis of the concept of a simple website with narrow subject matter by adding the concept of a vertical portal, in connection with which introduced the concept of optimal page load time of the informational kiosk, since the main task of the informational kiosk is the display of the user requested page containing the content within a certain time interval, and a key component of the kiosk GUI. Information and reference kiosk, as a small subscriber system in terms of functionality and volume of content, containing information in text, audio or video format, aimed at providing reference information to the user and giving him a means of interaction, by providing all available system objects and functions implemented in the form of graphical components, is not an exception. The article also discusses the key concepts of the information and reference kiosk, such as additivity, ergodicity, and entropy.

The implementation of the WaldBoost algorithm is considered, and its modification is proposed, which allows to significantly reduce the number of weak classifiers to achieve a given classification accuracy. The efficiency of the proposed algorithm is shown by specific examples. The paper studies modifications of compositions (ensembles) of algorithms for solving real-time pattern recognition problems. The aim of the study is to improve the known machine learning algorithms for pattern recognition using a minimum amount of time (the minimum number of used classifiers) and with a given accuracy of the results. We consider the implementation of the WaldBoost algorithm, which combines two algorithms: adaptive boosting of weak classifiers – AdaBoost (adaptive boosting), which has a high generalizing ability, and the sequential probability ratio test – SPRT (Wald test), which is the optimal rule of decision-making when distinguishing two hypotheses. It is noted that when using the WaldBoost, the values of the actual probability of classification errors, as a rule, are less than given because of the approximate boundaries of the SPRT, so that the classification process uses an excessive series of weak classifiers. In this regard, we propose a modification of the WaldBoost based on iterative refinement of the decision boundaries, which can significantly reduce the number of used weak classifiers required for pattern recognition with a given accuracy. The efficiency of the proposed algorithm is shown by specific examples. The results are confirmed by statistical modeling on several data sets. It is noted that the results can be applied in the refinement of other cascade classification algorithms.

A review of robotic systems is presented. The paper analyzes applied hardware and software solutions and summarizes the most common block diagrams of control systems. The analysis of approaches to control systems scaling, the use of intelligent control, achieving fault tolerance, reducing the weight and size of control system elements belonging to various classes of robotic systems is carried out. The goal of the review is finding common approaches used in various areas of robotics to build on their basis a uniform methodology for designing scalable intelligent control systems for robots with a given level of fault tolerance on a unified component base. This part is dedicated to industrial robotics. The following conclusions are made: scaling in industrial robotics is achieved through the use of the modular control systems and unification of main components; multiple industrial robot interaction is organized using centralized global planning or the use of previously simulated control programs, eliminating possible collisions in working area; intellectual technologies in industrial robotics are used primarily at the strategic level of the control system which is usually non-real time, and in some cases even implemented as a remote cloud service; from the point of view of ensuring fault tolerance, the industrial robots developers are primarily focused on the early prediction of faults and the planned decommissioning of the robots, and are not on highly-avaliability in case of failures; industrial robotics does not impose serious requirements on the dimensions and weight of the control devices.

A generalized algorithm for the verification of functional models and the rules for the verification of diagrams related by levels of detail were developed in this paper. The algorithm is based on the analysis of a tree which describes the decompose relations in functional diagrams. At each step of the algorithm, a pair consisting of a parent diagram and a functional diagram is selected, and the correlation of the arrows and their roles is checked for both. The formalization of the verification rules was based on the set-theoretic representation of functional diagrams in the form of labeled oriented graphs. The rules make it possible to map the position and roles of the arrows associated with the detailed function block of the parent diagram to the arrows of the child diagram. The following rules for each of the possible arrow roles were established: “input”, “output”, “control”, “mechanism”. The use of the logic programming language PROLOG was proposed for the implementation of the algorithm. A knowledge base structure comprised of 3 interrelated predicates to describe the tree of diagrams, nodes and edges of the graphs was suggested. A query to check the verification rules was formed, and methods of binding variables and fixing roles were considered. The analysis and verification of a fragment of a functional model for the production of vinyl acetate from ethylene was conducted as an example. The functional diagrams for the processes “Condensate separation” and “Vinyl acetate isolation” connected by a decompose relation were developed, their set-theoretic models were constructed, and the use of rules for the verification of each type of arrow were considered.

Design solutions of domestic VLSI were obtained as a result of the application of computeraided design tools of a foreign supplier (CAD Synopsys, Cadence Design Systems and Mentor Graphics), based on standard libraries of PDK elements (Project Design KIT) of factories and IC-modules also supplied mainly by foreign companies. As a rule, the developer does not have its own production facilities, using the services provided by foreign factories (fablesscompanies). Due to this fact, relevant are the studies aimed at the development of a complex of measures, excluding the possibility of unauthorized changes into IC, i.e. protection of projects against intentional hardware and technology violations made during the formation of the control information for handing it over to the production facility and/or in case of IC manufacture at the factory. This paper considers this task from the standpoint of the analysis of the methodology of design for testability (DFT), i.e., a complex of measures that provide obtaining solutions at the design stage. The solutions include the verification of the correct performance of the manufactured chip by means of external tests and/or self-testing procedures. It was proposed, inter alia: 1) to analyze the libraries of standard elements used in the project with full disclosure of their specifications; 2) to create nodes with the physical non-cloning function in the projects on the basis of the libraries of standard elements in models and analysis programs; 3) to analyze IP modules used in the project with the maximum disclosure of structure, methods and algorithms for providing test coverings; 4) to provide for the development in projects of special test kits and methods of their generation at the design stage of functions in order to detect malicious nodes and programs both within SoC cores and at the level of system buses; 5) to develop at the design stage and to apply during tests a technique of special hardware measurements of parameters of the manufactured circuits and analysis of their results, inter alia, according to measurements of delays in distribution of signals and/or buses current consumption.

A method has been developed for finding the shortest Hamiltonian path in an arbitrary graph based on the rank approach, which provides high efficiency and a significant reduction in the error in solving the problem of organizing the process of managing multiple transactions and queries when they are implemented in network databases. In many cases, existing solutions do not provide the necessary results in terms of access time and accuracy of the found solution. Using the developed method allows minimizing the idle time of computing devices, reducing the volume and time of data transfer from one device to another, increases overall scalability, minimizes data access time, etc. An important advantage of the proposed method is to reduce the number of elementary operations and the number of vectors being processed the queue of the operations of the request, which leads to a significant reduction in time to implement the procedures for the formation of echer di operations in the requests. Methods of graph theory were used in this paper. The effectiveness of the task solution was evaluated using a systems approach, system analysis and the theory of operations research. Processing of experimental data obtained during the work was carried out in accordance with the provisions of mathematical statistics.

The paper presents the main results of scientific and practical research in the field of special design reengineering and counterreengineering of radioelectronic devices. Methods and means of special design reengineering of functional modules of multilayer printed circuit boards and case microcircuits are presented. The basic process design for the reengineering of multilayer printed circuits of radioelectronic products is presented. The design is based on the physical principles of destructive and non-destructive decomposing test: mechanical processing and chemical etching, stereolaser structuring, IR imaging electrothermics and X-ray analysis. The article formulates positions and methodology of the circuit analysis of the basic architecture of electrical circuits and signal processes of radio electronic products by the configuration of the printed circuit, its electronic component base and their connected topologies. The article considers methods and techniques for the reengineering of radiotechnical circuits and signals enabling to reproduce the list of the electronic component base and the essential circuit technique, as well as to study the basic circuit characteristics of the appliance in four main modes: functional, in-circuit, peripheral and identification visualization. The methods and means of authentic performance of radioelectronic devices for a number of constructive and radiotechnical identifiers are considered. Technical methods and solutions for counterreengineering of radioelectronic devices have been developed.