Objectives. In view of the currently expanding practice of applying methods for configuring ontologies of designing information processes and systems, information technology (IT) specialists need to disclose the definition of such a new concept as functional synergetics. This concept is actualized by the course of development of virtual information technologies, forming the system foundation for methods of design ontologies and indicating attributes for the correct formation of design ontologies of relevant dynamic information processes and systems. In the present work, this is done by means of analytical review.
Methods. The analytical review is based on the authors’ vision of deepening the concept of synergetics as applied to a variety of modern information processes and systems. This context concessionally conjugates the combined use and consideration of such approaches as the method of ontologies (the major component of the resulting concession of methods), methods of cognitive semiotics, autopoiesis, and other manifestations of synergetics with related methods and techniques of emergent evaluation of the role and effectiveness of any occurring systemic changes. It is this combined dynamics of information processes and systems that allows the authors to put forward a developing treatment of the methods of synergetics as functional.
Results. The concept of functional synergetics was clarified and deepened based on the method of ontologies. In the theory of information processes and systems, it is manifested in updating ontologies accompanying scientific and engineering projects that use synergetics as an initial methodological basis. It turns out that the functional features of synergetics in the context of assessments and functional ordering of modern IT devices give it new opportunities in highlighting the significant indicators of system changes: properties, attributes, and manifestations of functionalsynergistic nature. It is these three concepts, revealed by synergetics as a functional eyepiece, that distinguish functional synergetics from the generally accepted definition of synergetics as such. Matching form to content, autopoiesis, development, and transformations occurring with informational processes and systems with their emergent consequences are the essence and feature of functional synergetics. Tracing what is happening in dynamics, in the inseparability of assessments and regulations of the set of properties, attributes, and manifestations of the analyzed processes to an even greater extent clarifies the essence and role of the concept introduced by the authors in the general classical theory of information processes and systems. In the related analysis, virtual reality, augmented reality, mixed reality, expanded reality, composite reality, coupled reality, geoinformation systems, multidimensional computer graphics, fractal graphics, holographic graphics, computer teletype games, X-reality, etc., which have essential dynamic characteristics and properties, are included here as objects of research and design.
Conclusions. Improvement of the theory and practice of creating and using information processes and systems from the position of recognizingthe accelerating speed and dynamics of how their properties and indicators are modified leads the synergistic methodology of assessments and control mechanisms to the emergence of a clarifying concept of functional synergy. This is a complex and dynamic concept, which includes its interpretation of the positions of classical synergetics and related paradigms of cognitive semiotics, etc. The method of ontologies, which is gaining more and more popularity, is the main means and tool of such unification. When combined with cognitive semiotics, functional synergetics becomes a powerful science-intensive tool for further development of the theory and practice of modern multimedia intensified information systems and their information fields described by both imperative and convivial paradigms.

Objectives. The paper deals with the equivalence of program schemes. According to A.A. Lyapunov and Yu.I. Yanov, the founders of this theory, a program scheme is understood as a program model wherein abstraction from contensive values of operators and expressions is performed. In this case, the program structure containing symbolic notation of operators and expressions remains unchanged while maintaining their execution sequence. The programming language model presented in the paper contains basic constructs of sequential languages and is the core of the existing sequential programming languages. The paper aimed at developing an effective algorithm for studying equivalence (nonequivalence) of program schemes of sequential programming languages.
Methods. An algebraic approach to specifying semantics of programming languages was used for studying the equivalence of program schemes.
Results. A process semantics being the new algebraic approach to specifying the formal semantics of sequential programming languages was proposed. The process semantics was specified by matching programs (program schemes) with a set of computation sequences. The computation sequence was understood as the execution sequence of actions (commands and tests) of the program. Two types of concatenation operations (test–command and command–command) and the merge operation, which properties are given by axiomatic systems, were defined in the introduced semantic domain. The finiteness of the semantic value representation in the form of systems of recursive equations was proved. The algorithm for proving the equivalence (nonequivalence) of systems of recursive equations characterizing semantic values for a pair of program schemes was proposed, which implies the equivalence (nonequivalence) of programs in the strong sense.
Conclusions. The paper demonstrates the efficient use of the proposed algorithm for proving the equivalence of sequential program schemes excluding side effects when calculating expressions, i.e., sequential computation of the expression more than once does not change anything. The example of proving the equivalence of program schemes by two methods—the well-known de Bakker–Scott fixed-point induction method and the method proposed by the author—is given. Comparison of the above methods testifies not only to the new method′s effectiveness but also to its significant simplicity, proved in practice by students who performed corresponding tasks when studying the Semantics of Programming Languages at the Institute of Information and Computing Technologies at the National Research University Moscow Power Engineering Institute (Moscow, Russia).

Objectives. Digitalization of the economy has led to a situation in which organizations accumulate huge amounts of digital data, the loss or damage of which leads to irreparable damage to the organizations. The issue of increasing data safety is relevant. One of the ways to improve the safety of data is backing them up. The study aimed to develop an effective strategy for backing up data for critical enterprise information systems.
Methods. The method for solving the problem was to create backup copies of enterprise information systems using a flexible architecture based on the backup—as a service in external cloud structures—in combination with technical resources of the organization.
Results. This article discussed backup solutions and tools, which include: backup volumes and schedule, target point and recovery time. The strategies and mechanisms of data backup were analyzed. The most common backup mechanisms are removable media, backups, external hard drive, hardware, backup software, cloud backup services. To create backups on a network, a large external hard drive is created and archival software is used to save changes to local files on that hard drive. This article covered: backup strategy, concept of backup storage, different types of backup storage methods, including network storage, external hard drives, and cloud storage. The main provisions and rules for backing up critical information systems were described. The rules for copying servers were given.
Conclusions. This article discusses a data backup architecture for mission-critical enterprise information systems. The authors believe that there should be at least three backups, two of which are located in the “cloud.” The 3–2–1 strategy developed by the authors gives quite satisfactory results for the safety of critical data.

Objectives. The most important distinguishing feature of satellite communication networks (SCNs) is topology, which consolidates the scheme for combining nodes and communication channels into a single structure and largely determines the main characteristics of communication systems. The following topologies are used in SCNs: fully connected, tree-like, ring-shaped, and radial (“star” type). The topology can be changed depending on the tasks being solved; for example, to ensure high reliability rates. The most frequently used indicator characterizing the reliability of communication networks is the readiness factor. Considering the SCN as a complex recoverable system, it is advisable to analyze the operational readiness factor along with the readiness factor. This paper investigates the influence of the network topology on the reliability of the SCN.
Methods. Queuing theory was used to analyze the flow of events, that is, the flow of failures and recoveries.
Results. Assuming that the exponential Mean Time Between Failures (MTBF) model can be used for a central node with a radial network topology, the time dependences of the operational readiness factor were obtained. The reliability of networks with ring and radial topology was compared in terms of the operational readiness factor.
Conclusions. To achieve a higher reliability, it is necessary to use an SCN with a radial structure. For example, on a time interval of 12000 h, the operational readiness factor of a two-node SCN with a radial structure is 0.9, and for an SCN with a ring topology with the number of nodes 2, 3, 4, it is 0.7, 0.59, and 0.5, respectively. The study also showed that radial topology is more efficient even with less reliable nodes, that is, with higher failure rates. The advantage of a radial network topology increases as the number of nodes increases. However, in an SCN with a radial topology, failure of the central unit leads to complete degradation of the entire system.

Objectives. Phase-shift keyed (PSK) signals are widely used in many telecommunication, communication, and cellular information transmission systems. Phase-shift keying provides a higher noise immunity than amplitude and frequency modulations do. An increase in the modulation order of such a signal leads not only to an increase in its spectral efficiency, but also to a certain decrease in the noise immunity of reception. To ensure a high noise immunity of reception of multiple phase-shift keyed (MPSK) signals, a demodulator should provide the coherence of the reference oscillation with the carrier. Ignorance of the frequency and phase of the received signal leads to significant energy losses. The purpose of this work was to synthesize and analyze algorithms for receiving MPSK signals with phase fluctuations caused by changes in the carrier frequency due to the Doppler effect against the background of white Gaussian noise.
Methods. The problem was solved using the apparatus of optimal nonlinear filtering and methods of statistical radio engineering.
Results. A demodulator was synthesized, which includes two interconnected units. One of them is a discrete symbol estimation unit, at the output of which a decision on the received symbol is issued, and the other is a phase-lock circuit. Analytical expressions were derived to estimate the characteristics of the receiver noise immunity as functions of the signalto-noise ratio and fluctuation parameters. It was shown that the synthesized quasi-coherent algorithm compensates well for the MPSK signal phase fluctuations caused by the instability of the master oscillator and the Doppler effect.
Conclusions. Comparison of the results of this work with results obtained in the case of the absence of fluctuations in the initial phase showed that, at a high relative speed of the transmitter and the receiver (satellite radio channel), the energy loss is no more than 1 dB, and at lower speeds of the objects, it is about 0.2 dB and less.

Objectives. The study aimed to construct and analyze a computational model of an electro-optical repeater of radio pulses, capable of reconstructing a pulsed radio image with subnanosecond resolution in a single reception under conditions of additive noise.
Methods. Numerical methods of network analysis were used, which are the basis of specialized computer-aided design systems, numerical methods of statistical radio engineering.
Results. A radiophotonic radio pulse repeater scheme was constructed, which is implemented based on the principle of fractional multiplexing with delayed feedback. Software simulation of infrared repeaters in the Simulink environment (Trial Version Soft) was developed, which allows for analyzing and investigating the efficiency of the optical reconstruction method of radio pulses using a fractional multiplexing with delayed feedback. It is shown that repeaters schemes, implemented on the principles of fractional multiplexing with delayed feedback, are able to effectively solve the scientific and practical problems of multiple probing of objects with ultrashort pulses (USP) for obtaining a radio image of a target with reliable reproducibility. In the course of numerical simulations, it was found that the two- and four-cascade schemes of delay lines with feedback do not provide reliable reproducibility in the case of reconstruction of an ultrashort pulse with a complex time profile. At the same time, the scheme with a cascade of 8 delay lines showed good results, providing a correlation reproducibility of more than 0.9. In this case, the scheme of an electro-optical repeater with a cascade of 16 delay lines did not make a significant contribution to increasing the accuracy of the USP reconstruction if compared to the scheme with a cascade of 8 lines; therefore, the latter can be determined as an optimal solution. An electro-optical method was proposed for solving the radio engineering problem of stroboscopic registration and reconstruction of subnanosecond radio pulses, which represent the signature of the radio image of dynamic objects for active radio imaging systems.
Conclusions. It was found that an electro-optical repeater with 8 delay lines is able to recover a complex pulse reflected from a target in 30 iterations with a correlation coefficient greater than 0.9 between the reference and reconstructed pulses at a signal-to-noise ratio of at least 9 dB.

Objectives. The study aimed to examine vortex structures formed during the interaction of incident and reflected shock waves in a cylindrical channel. The shock wave was described by the Hugoniot relations, which make it possible to determine the parameters of the gas behind the shock front by a given Mach number and the values of the gasdynamic parameters ahead of the pressure jump. The propagation of a strong shock wave (Mach number was 20) in argon was simulated.
Methods. The methods of mathematical modeling were used. A parallel algorithm for solving two-dimensional equations of gas dynamics in cylindrical coordinates (r, z, t) was developed and a new version of the NUTCY_ps program created. The calculations were performed on an MVS-100K supercomputer. Results. Two methods of parallelization when solving a system of equations were considered. Using a specific task as an example, a comparison of the effectiveness of these methods was conducted. A parallel algorithm was developed and a program was upgraded for solving two-dimensional equations of gas dynamics in cylindrical coordinates (r, z are spatial coordinates, t is time). Numerical calculations were performed to simulate: 1) the shock wave incidence to and reflection from a metal screen; 2) the propagation of the shock wave through a hole in the screen; 3) the propagation of the shock wave through a cylindrical channel and its reflection from the bottom of the channel and interaction with the incident wave.
The results obtained by the parallel supercomputer with different numbers of processors are presented. It is shown that using 16 processors, it is possible to reduce the computation time for getting a solution for the test problem by approximately 12 times.
Conclusions. It is shown that the interaction of incident shock wave and the one reflected at an angle leads to the formation of regions with low and high gas densities, as well as vortex flows. The vortex interaction area (turbulence zone) gets a complex shape. The article discusses the possibility of carrying out full-scale experiments in shock tubes or using a laser shock tube. Such studies would make it possible to compare experimental data with the results of numerical simulation and, on their basis, to develop more advanced models of turbulent motions.

Objectives. Recently, interest in studying local nonequilibrium processes has increased in the context of the development of laser technologies, the possibility of reaching ultrahigh temperatures and pressures, and the need for a mathematical description of various physical processes under extreme conditions. In simulating local nonequilibrium processes, it becomes necessary to take into account the internal structure of investigation subjects, which significantly complicates the classical transport models. An important stage here is to construct mathematical models of various physical fields in which their spatiotemporal nonlocality should be taken into account. For these purposes, hyperbolic equations are used for a wide class of phenomena and, first of all, for unsteady-state heat conduction processes based on the generalized Maxwell–Cattaneo–Luikov–Vernotte phenomenology. Mathematical models in the form of boundary value problems for hyperbolic equations are called generalized boundary value problems. These problems differ significantly in solving difficulty from the classical ones based on Fourier phenomenology. The specificity of these problems is the relative simplicity of the initial mathematical models, together with the difficulty of solving them in an analytically closed form. Hence, very little success has been achieved in finding exact analytical solutions to problems of this kind. The most acceptable approach to solving them is operational calculus. However, it gives analytical solutions in the Laplace transform space as complex functional structures, the inverse transforms of which are not available in well-known reference books on operational calculus. On this path, serious computational difficulties arise. The study aimed to analyze a set of nonstandard transforms arising from the operational solution of mathematical models of local nonequilibrium heat transfer and to obtain their inverse transforms.
Methods. Methods and theorems of operational calculus, methods of contour integration of complex transforms, and the theory of special functions were used.
Results. Operational calculus was developed for mathematical models of local nonequilibrium heat transfer in terms of the theory of unsteady-state heat conduction for hyperbolic equations (wave equations). Nonstandard operational transforms, the inverse transforms of which are unavailable in the literature, were considered. It was shown that the presented transforms are common to operational solutions of a wide class of generalized boundary value problems for hyperbolic equations in the theory of heat conduction, diffusion, hydrodynamics, vibrations, propagation of electricity, thermomechanics, and other areas of science and technology. Partially bounded and finite domains were explored. Illustrative examples were given, namely, the results of numerical experimental studies of a local nonequilibrium heat transfer process that took into account the finiteness of the heat transfer rate, which had a wave character. The latter was expressed by the presence of the Heaviside step function in the analytical solution of the problem. The physical meaning of the finiteness of the heat transfer rate was substantiated. The isochron was constructed for the temperature function in a partially bounded domain. It was shown that the temperature profile has a discontinuity on the surface of the propagating wave front. This leads to the retention of heat outflow beyond the discontinuity boundary. This is a characteristic feature of the analytical solutions of the wave equations, along with the possibility to describe the analytical solution of the problem as equivalent integral relations, which noticeably simplify numerical calculations.
Conclusions. The inverse transforms of nonstandard operational (Laplace) transforms were presented, which are contained in the operational solutions of a wide class of problems of local nonequilibrium (heat, mass, momentum) transfer processes, electrical circuits, hydrodynamics, oscillation theory, thermomechanics, and others. Illustrative examples were given, and the possibility of transition from one form of an analytical solution to another equivalent form was shown. The presented analytical solutions of hyperbolic heat transfer models in canonical domains are new in classical thermal physics.