Sets of vectors of decimation indices IS = (id1, id2, …, idn) for the formation of sets of five-fold Gold-type sequences in finite fields GF(5S) (S = 3, 4, 5, 6) based on М- sequences with verification polynomials hМП(x) for periods N = 5S – 1 < 20 000, are presented. The sets include both the well–known decimation indices obtained by Trachtenberg, Helleset, Kumar and satisfying the condition LCD(idi, 5S – 1) = 1 (LCD is the largest common divisor), and the newly found indices that allow the formation of sets of five-fold Gold-type sequences with volumes VS = N + 1 and low levels of periodic auto- and the cross-correlation functions. For the considered values of S, boundary estimates of the maximum value of the correlation function modulus Rmax are given.

Digital transformation of enterprises is a mandatory stage of the transition to digital economy. The concept of “digital transformation” is analyzed. The fact of the emergence of new risks in the activities of enterprises due to a significant increase in their information connections are stated. The subject of the study is the technical risks of an enterprise in the process of its digital transformation. Three groups of risks are identified: unauthorized access/theft/distortion of information using local access means; vulnerability of network information transmission channels; unclear distribution of areas of responsibility. The features of each risk group are analyzed and measures to reduce their level for the enterprise are proposed.

A method for creating an integral assessment of the quality of difficult-to-formalize object is developed using the example of analysis of forest ecosystem sustainability. The proposed method is based on the procedures of multicriteria analysis and qualimetry of models and multi-model complexes. A two-level classification of sustainability indicators is used, including a set of specific and general indicators. An integral assessment of sustainability is created on the basis of the values of generalized indicators. The most general case is analyzed when the indicators under consideration have a complex structure, are measured in various scales (quantitative and qualitative) and can be related non-linearly to each other. The method description is carried out using the example of deriving an integral assessment of sustainability on the basis of three generalized indicators characterizing the productive capacity, sanitary condition, and biodiversity of forests. Each of the generalized indicators represents a linguistic variable. The essence of the method is the application of production models of preference of the decision maker and processing of expert survey data by the methods of the theory of fuzzy measures. Using the method allows to describe and take into account the nonlinear influence of a set of generalized indicators on the resulting assessment of stability and thereby obtain the most reliable results. Based on the proposed method, it is possible to obtain estimates of the forest integral sustainability, to conduct a comparative analysis of forest vegetation sites with different values of generalized indicators, as well as for the same site at different points in time.

A semi-Markov model is constructed to describe the functioning of a single-component servicing system with a storage device of finite capacity, in which the quality of service of requests is monitored. In case of an unsatisfactory result, repeated servicing of the application is carried out until satisfactory quality is achieved. The stationary distribution of the nested Markov chain is found, the stationary characteristics of the system are determined, depending on the probability of high-quality service of requests: stationary distribution of the queue over time, the average stationary sojourn times in states, the average queue length, the average request sojourn time in the queue and in the system.

It is noted that measuring the air parameters of airplanes and other aircrafts movement is necessary for solving control problems and ensure safety of traffic within the atmosphere. The features of widely used systems for measuring air parameters with receivers and sensors of incoming air flow parameters distributed throughout the fuselage are considered. Pneumatic lines and electrical cables that connect these receivers and sensors to an on-board computer generating system output signals, complicate the design and increase the system weight and cost. Receivers and sensors protruding beyond the fuselage skin disrupt the aerodynamics of the aircraft and increase its trajectory visibility. The systems being developed for measuring air parameters using vortex, ion-tag and ultrasonic methods for monitoring the oncoming flow and built on the basis of one (integrated) multifunctional flow receiver, also do not eliminate all of these shortcomings. The principles of constructing a system for measuring the air parameters of an aircraft's movement with an integrated fuselage flow receiver with built-in primary information converters and a system computer are formulated. Analytical models of primary informative signals, algorithms for their processing and generation of system output signals are developed. The competitive advantages and scope of application of the system under consideration are discussed.

Based on analysis of the traditional stages of computer-aided design (CAD), especially at the stages of preliminary and detailed design, the main problems leading to insufficiently accurate engineering, experimental and software results in the development of an automated control and monitoring system for flexible production area (FPA) in the field of mechanical engineering are identified. Based on the initial data of the terms of reference for the computer-aided design process, its modern tools, as well as the requirements and tasks, standards for the design stages, especially the stages of preliminary and working design, a block diagram of the computer-aided design of the FPA control system with a detailed presentation of these stages is proposed. According to the layout diagram of the object of study of FPA for cutting and annealing in the production of aluminum evaporators for domestic refrigerators, the types, functions and positioning of information and measuring tools on the active elements of the production site are determined. To describe the initial positioning data and geometric data of sensors, control elements of the FPA control system in the form of logical links, descriptive products, coordinates, and expressions in the form of mathematical conditions for positioning sensors in a 3-dimensional coordinate system are given. The characteristics of the functions of the information-measuring and control system of the studied FPA are determined, their coordinates are determined depending on the measurement and implementation of the positions of the active elements, the routes for manufacturing the production product and the automation scheme.

The use of phase measurements in consumer navigation equipment has become the main way to increase the accuracy of navigation determinations. The methods used to resolve the ambiguity of phase measurements require additional information and have a number of known disadvantages. Limitations are identified in the implementation of methods of synthesized wavelength and non-multiple scales for resolving the phase measurements ambiguity in the GLONASS system at the present time. A non-brute force method for resolving the ambiguity of phase measurements in a satellite radio navigation system is proposed, which does not require an excessive number of measurements. A theoretical substantiation of the computational procedures of the multiple scale method are carried out. The proposed method uses mathematical number theory to calculate an integer number of phase cycles. Algorithms are developed to implement this method at two carrier frequencies, and the results of experimental processing of phase measurements of pseudo-range in the GLONASS system are presented. These algorithms can be used both when solving the positioning problem in precision-accuracy positioning mode, and when determining highly dynamic objects orientation of in real time. Based on the considered method of non-multiple scales, algorithms for resolving the ambiguity of phase measurements obtained using foreign satellite navigation systems GPS, Galileo, Beidou can be developed.

The influence of pressure on the results of measuring the volume fractions of gas components using Raman spectroscopy is considered. The nonlinear nature of the influence of pressure on the light flux is revealed in the spectral range from 1380 to 1399 cm–1 for the isotopologue of carbon dioxide 12СО2 and in the spectral range from 1361 to 1379 cm–1 for the isotopologue of carbon dioxide 13СО2. The Raman spectra of gas mixtures of known isotopic composition are measured at different pressures. The function of deviation of the integral light flux from the linear dependence and its coefficients are found using the nonlinear least squares method. It is proposed to use this function to calculate correction factors in calibration functions. Calibration functions relate the light flux recorded by the radiation receiver to the volume fraction of molecules of the substance under study. The use of correction factors enables to increase the accuracy of measuring the volume fraction of the gas components under study.

In order to establish the causes of the periodic alternating distribution of the magnetic stray field along the surface of an underground gas pipeline, the strength of the magnetic stray field H on the surface of an extended pipe made of St20 steel with an elastically bent section in the form of an arch is investigated. H measurements are carried out both tangentially to the pipe and normal to it. It is been established that the alternating stresses arising in the wall of an elastically curved pipe are the cause of its uneven and inhomogeneous magnetization in the Earth’s magnetic field, and, consequently, the periodic alternating change in the magnetic stray field measured on its surface. The “wavelengths” of the changes in the normal and tangential components of the scattered magnetic field strength H of the pipe are shown to be comparable to the length L of the arch created on it, and their maxima are shifted relative to each other by half L. It is concluded that sections of underground oil and gas pipelines (arches), experiencing bending deformations, are magnetized in the Earth's magnetic field non-uniformly, which causes periodic changes in the magnitude and direction of the magnetic stray field on their surface. The stress state in such areas changes sharply compared to the calculated one, the state of the insulation deviates from the norm, and as a result, preconditions arise for stress-corrosion destruction. It is proposed to monitor changes in the position of the main pipeline in the ground during operation relative to the design one, as well as to monitor the seasonal dynamics of the stress state in the area of flexural deformation using the magnetic method in order to assess the service life and bearing capacity.

Love wave propagation in layered media parallel to the layers of the structure along the cylindrical surfaces with homogeneous boundary conditions is investigated. As part of the study, a dispersion equation was obtained and solved with respect to the wave number. Based on the obtained solutions, graphical dependences of the wave propagation velocity on the ultrasound frequency are plotted, and the influence of the surface curvature radius on the wave velocity is shown.

The general dynamics of multi-link systems that implement the “walking” principle of movement are described, and an approach to constructing a bond graph model of a walking robot is developed. The presented mechanisms are modeled to evaluate a number of specific requirements, such as dynamics, positioning accuracy and energy expended for movement. An approach to changing single-node bond graphs to bond graphs in the format of multi-connections of nodal vectors and, as a consequence, simplifying the visualization of the generated model is described. The construction of a bond graph model under conditions of non-determinism of external influences, which are simulated by the random nature of the information received, is considered.

The problem of monitoring the state of complex objects of various natures based on classification and regression analysis of time series data is considered. Hybrid neural network models of classification and regression analysis are developed and studied using data on the functioning of three types of systems: spacecraft, information system and economic system, presented in the form of time series. For all types of systems, the proposed hybrid models demonstrate an advantage in accuracy. A genetic algorithm is developed for the automatic search of hybrid neural network models, with the help of which models of varying complexity are generated with an accuracy no lower than for models developed manually. As a result of the search, it is noted that the generated hybrid neural networks show results close to the maximum value of the fitness function. The fact is considered as experimental confirmation of the constructed solution to be close to optimal for certain search parameters.