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The relevance of the study lies in the need to assess the capabilities of the BRICS and G7 international alliances in the context of increasing uncertainty and shifting centers of global leadership. The purpose of the study is to conduct a comprehensive comparative analysis of the BRICS and G7 countries' scientific, educational and digital capabilities to determine the prospects of the impact of the two international alliances on the development of the global economy.Objectives: to study the indicators of the BRICS and G7 countries' scientific and educational potential; to study the components of the BRICS and G7 countries' digital potential; to substantiate the tools for expanding the scientific, educational and digital potential of the countries to strengthen the BRICS position in the global economy.Methodology. The study is based on the use of methods of statistical information collection, comparative and economic analysis, systematization, and the graphical method.Results. The analysis of indicators of the BRICS and G7 countries' scientific and educational potential shows, on the one hand, the advantage of the alliance of developed G7 countries and, on the other hand, the clear leadership potential of China, Russia and Brazil in various groups of indicators, which determines the probability of strengthening the positions of these countries and the entire BRICS alliance in the implementation of an active government policy in the field of education and science. The current gap between the BRICS alliance and the G7 countries in terms of digital capacity has narrowed during the pandemic, which creates the preconditions for developing countries to strengthen and achieve digital leadership in the world.Conclusions. It is concluded that the strengthening of the BRICS countries' position on the world stage in terms of GDP over the past 10 years, as well as the presence of strong elements of scientific, educational and digital potential of individual countries of this alliance, and their strengthening during the pandemic have formed the prerequisites for the alliance to take leadership positions in the near future.

The hydrotransport system of Andrei Varichev Mikhailovsky GOK JSC used for iron ore processing tailings was studied with the aim of establishing its performance when using slurry pipelines with and without polyurethane coatings of their internal surfaces under mass concentration variations of 10 to 70 %. It has been established that the use of internal polyurethane coatings significantly reduces the specific head losses in hydraulic transportation of thickened slurry tailings for iron ore processing tailings. However, the technical and economic calculations performed failed to confirm the economic efficiency of their application for the slurry pipelines of the tailings facility hydrotransport system of Mikhailovsky GOK at any slurry thickening values, due to the significant payback period of capital investments caused by the relatively high current cost of polyurethanecoated pipelines. At the same time, a significant reduction (almost by a factor of four, provided that the current production volumes are maintained) in hydrotransport (energy) costs and maintenance costs of pressure slurry pipelines were identified for a transition to slurry tailings thickening to 50 % solids (excluding the capital and operating costs for the thickening system, reconstruction of the slurry pumping stations and additional measures for the distribution of a thicker slurry at the tailings storage facility). It is proposed to use the results obtained in the reconstruction of the slurry tailings hydrotransport system at the tailings facility of Mikhailovsky GOK with a conversion to hydraulic transportation of bulk concentration tailings thickened to 50 % in ∅820 mm slurry pipelines.

The paper considers the possibility of using a single version of the design of the measuring cell as part of an installation for measuring the thermophysical properties of solid materials using the methods of regular modes of the first, second and third kind.

This article discusses work on assessing the digestibility of a concentrate of Hermetia illucens larvae in fish with gastrointestinal digestion (rainbow trout Oncorhynchus mykiss, Russian sturgeon Acipenser gueldenstaedtii, red tilapia Oreochromis mosambicus × O. niloticus). It was found that this digestibility index of the larvae concentrate was 67–74%. At the same time, fish species consumed larvae protein at 91–97%, the digestibility of residual fat was 90–94%, and easily hydrolyzed carbohydrates amounted to 52–68%. Сhitin of H. illucens was digested 25–35% and did not adversely affect the digestion of protein and fat in the fish species studied. The digestion rates of the H. illucens larvae concentrate, protein, and easily digestible carbohydrates in O. mosambicus × O. niloticus are statistically significantly higher than in Onc. mykiss, while in A. gueldenstaedtii they were intermediate in comparison with tilapia and trout. This corresponded to the duration of food passage through the intestinal tract, which in O. mosambicus × O. niloticus, Ac. gueldenstaedtii, and O. mykiss came to 7.8, 9.6, and 15.7 hours, respectively. Fat and chitin were digested by red trout significantly more efficiently than other fish species. This corresponded to the duration of food passage through the intestinal tract, which for tilapia, sturgeon, and trout came to 7.8, 9.6, and 15.7 hours, respectively. The degree of digestibility of fat and chitin by trout was significantly higher than that of other fish species.

In the article the results of a new type of piezo-electric step-engine research are presented. The original construct of piezo-electric step-engine is contained in special engineering lever called grab device that can organize back and forward rod’s motion with only one piezo element activity. To choose the effective process of piezo-electric step-engine work the mathematical model was created. This mathematical model describes inner piezo-electric step-engine process with features of contact and electroelastic deformation. Using the ANSYS application package, а finite element model of the piezo-electric step-engine has been developed. This finite element model allows estimate the stress-strain state of structural elements of the piezo-electric step-engine and determine the effective step-by-step operation mode of the piezo-electric step-engine. Using the finite element model, the influence of the piezo-electric step-engine operating mode parameters on the amount of displacement of the rod is studied. According to results of experimental studies, the proposed numerical model allows to simulate the dynamic process of step-operation of a piezo-electric step-engine with an error of no more than 6 %. This finite element model include the external load on piezo-electric step-engine and can be used to design piezo-electric step-engine of various fields of application.

Mathematical models have been developed for the calculation of measurement errors of the coefficients of the heat conductivity and thermal diffusivity of thermal insulating materials. A technique for selection of the following optimal parameters was created, based on models: duration of the heat pulse and the chief structural dimensions of the measuring device. Optimal conditions for applying the algorithm for processing the experimental data were also defined.

In the article the results of new piezoelectric step-engine research are presented. The original construct of piezoelectric step-engine is contained in special engineering lever called grab device that can organize back and forward rod’s motion with only one piezo element activity. To choose the effective process of piezoelectric step-engine work the mathematical model was created. This mathematical model describes inner piezoelectric step-engine process like a non-linear vibrational system. The mathematical model identifies speed of piezoelectric step-engine elements over the vibration period with different frequency, load level and voltage. The prototype of piezoelectric step-engine was produced. Experimental issues were conducted. Piezoelectric step-engine’s technical specifications are positioning accuracy over 10–6 meter, speed of movement over 10 mm per minute with weight of load to 1 kg and voltage to 100 Volt. On the results of experimental research it is defined that mathematical model enables to model working process of piezoelectric stepengine with an error not more than 10 %. This research verifies viability of proposed construction and provides the way to increase output power of piezoelectric step-engine.

The dynamics of the main echocardiographic parameters of left ventricular myocardium (LVM), reflecting the mechanisms of myocardial remodeling of left ventricle in patients with metabolic syndrome and sleep obstructive apnea syndrome (SOAS) was studied. The research involved 98 men who are overweight (BMI > 30 kg/m 2 ) with established earlier a diagnosis of hypertension and blood pressure stabilization achieved against a background of adequate medical therapy. Study participants underwent cardiorespiratory monitoring night’s sleep for diagnosis of sleep obstructive apnea syndrome with assessment of apnea/hypopnea index and average nocturnal saturation, and EchoCG was performed to assess the structural parameters of LVM, such as left ventricle (LV) diameters, the thickness of the interventricular septum and posterior wall of LV with further calculation of LVM mass index. The data revealed reliable correlation of left atrium length and thickness of the left atrial posterior wall with an index of apnea/hypopnea (р < 0.05). No significant association study of structural parameters of LVM with the level of nocturnal hypoxemia have been identified. The study conclusions were drawn about the likely impact of the periodic independent upper airway obstruction in the remodeling of the left ventricle in the absence of a direct influence on the process of remodeling nocturnal hypoxemia.

A computer simulation approach to sintering of low-temperature ceramics has been developed within the framework of the micromechanics of heterogeneous media. It is taken into account that the reinforcement of the refractory component can be formed at different structural levels determined by the particle fraction size. The formation of the reinforcement of interacting refractory particles in individual sintered layer mesovolumes causes the pore structure formation, and the heterogeneous pore distribution through the mixture layer thickness in the initial compact determines the shrinkage anisotropy of the sintered ceramics. The conditions are determined in which the reinforcement of refractory components is formed at different structural levels. An initial block of layers formed of a mixture of refractory and low-melting components with a binder was obtained in the laboratory. Low-temperature ceramics samples were synthesized. The structure of a separate layer of the sintered ceramics was examined by X-ray tomography. Experiments were conducted to confirm the reliability of the sintering simulation results obtained with taking into account the effect of the heterogeneous component distribution and fractional composition of the initial mixture on the properties of low-temperature ceramics.

Computer simulation methods have been applied to study the processes of low-temperature ceramics synthesis corresponding to technological processes. The simulation is performed for micron- and nanosized powders with different morphology. The synthesized composite medium has the characteristics (microlayer thickness, pore volume fraction, etc.) that reflect imperfections in the initial dispersion. The developed model allows one to examine the governing factors of physical and chemical processes in low-temperature ceramics synthesis.

A mathematical model for use in calculating the relative errors in measurements of the volumetric heat capacity and thermal diffusivity of heat-insulating materials through the use of a linear pulse heat source is developed. Techniques for processing experimental data and for selecting the basic structural dimension of the measuring device and the optimal length of the thermal pulse are created.

A mathematical model is developed for the errors in measuring the thermal diffusivity and thermal conductivity of thermally insulating materials using the theory of heat conduction. A method is created for selection of optimal heat pulse duration, conditions for processing of experimental data, and basic design size of a measuring instrument.

A new dataset has been assembled to compare the efficiency of simultaneous localization and mapping algorithms out of doors in areas with high a priori uncertainty. The images were made using a high-resolution stereo camera, with reference camera trajectories being used to calculate movement within the scene based on manually identified key points. The resulting dataset of images can be used to compare the robustness of simultaneous localization and mapping algorithms under complex lighting conditions outdoors.

Physical and mathematical models of the heat transfer process in the reviewed control object are considered. On the basis of the formulated boundary value problem of thermal conductivity (using the Laplace and Hankel transformations) the calculated dependences for calculating the desired values of thermal conductivity and thermal diffusivity are obtained. An algorithm for the functioning of the information-measuring and control system for implementing the developed method for measuring the thermophysical properties of materials is presented.

The pressing problem in the space domain is the development of large-sized reflectors for spacecrafts. The specified criteria for reflector structure are precise reflector surface shape and structure mass. Precise reflector surface shape during long-term performance is provided by the alignment of piezoelectric motors used in the reflector structure. These motors exhibit both limited mass-dimensional coefficient and can produce high force. Piezo-motor is distributed mechanical – acoustic oscillation system. In the piezo-motor mechanical – acoustic oscillation is generated by PZT-stack being transferred to the oscillator then to the load action element. The objective of the work is the study the alignment of distributed oscillation systems in piezo-motors. The novelty of the work is using the alignment of oscillator impedance and load impedance to determine the performance resonance frequency of distributed oscillation system in piezo-motor. This method simplifies the possibility of analyzing distributed in piezo-motor oscillation system characteristics. The method was tested under different in piezo-motor load modes.

This paper describes the numerical conjugate problem solution algorithm for fluid-deformable body system. It is based on respective subtasks according to physical principals. To solve these subtasks, independent "black box" program modules are used. These modules are connected by conjugate conditions. Fluid phase domain boundary interface is discrete movable i.e. it is not movable on the integration time step, but its position is adjusted on the next time step.

The development of spacecraft large-sized reflectors is one of the most urgent issues for the space industry. The reflector structure is to meet such principle criteria as high accuracy in reflective surface configuration and weight. The accuracy in the reflective surface configuration during continuous operation is ensured by the control system. The authors suggest using piezo motors in the control system. The motors of such type of certain small mass-overall characteristics can create high force. This paper presents a new piezo motor design and its operation. A mathematic model of piezo motor operation modes has been worked out which became the basis for setting new designed piezo motor operation modes depending on different loads. The results of the experimental tests of the new designed piezo motor confirmed the results of the theoretical calculations.The development of spacecraft large-sized reflectors is one of the most urgent issues for the space industry. The reflector structure is to meet such principle criteria as high accuracy in reflective surface configuration and weight. The accuracy in the reflective surface configuration during continuous operation is ensured by the control system. The authors suggest using piezo motors in the control system. The motors of such type of certain small mass-overall characteristics can create high force. This paper presents a new piezo motor design and its operation. A mathematic model of piezo motor operation modes has been worked out which became the basis for setting new designed piezo motor operation modes depending on different loads. The results of the experimental tests of the new designed piezo motor confirmed the results of the theoretical calculations.

A study of the effect of a complex probiotic preparation with bacteria of the genus Bacillus and a microdose of larvae of the fly Hermetia illucens on the physiological. parameters of fish has been carried out. It was established that introduction of the complex into artificial feeds for tilapia and Russian sturgeon juveniles during their incubation in recirculating aquaculture systems improves the digestion efficiency and increases the rate of fish growth and body mass accumulation. In tilapia, a decrease in the cholesterol level was revealed, while in sturgeon, an increase in the hemoglobin content was found. It was noted that a probiotic with biologically active agents H. illucens had a stimulating effect on the development of sexual gonads in female sturgeon fry, promoted an increase in the ovary mass, and provided for the development of eggs without morphological disturbances.

The present paper describes ways of increasing the accuracy of measurements of thermophysical properties (namely, thermal diffusivity) of materials. The knowledge of these characteristics is very important for modeling industrial processes, since their high-accuracy determination can reduce wasteful consumption of energy resources while developing novel thermal insulation materials, technologies, as well as methods for building construction. The method proposed herein is based on periodic heating and can be used to improve the measurement accuracy and find the optimal parameters for producing thermal insulation materials. Periodic temperature oscillations were generated by means of the Peltier element. Mathematical and physical models were developed, and the measurement setup was automated using the LabView graphical programming environment. The analysis of possible error sources was performed, and the ways of decreasing error values were suggested. The equipment was experimentally calibrated using a standard material (Plexiglas), and the obtained data proved the appropriateness of the developed mathematical model. Moreover, a number of tests were performed with a nanomaterial, namely, graphene nanoplatelets (GNPs). The proposed method and the experimental measurement setup made it possible to reveal a strong dependence between the thermal diffusivity of the GNPs and the moisture content. This finding will be considered in further studies concerning the above-mentioned nanomaterial.

Methods of measuring the thermal characteristics of materials using periodic heating are considered. A classification of the regular-mode methods of the third kind as a function of the method of producing the temperature oscillations, forms of temperature waves and a mathematical model, used in the method, is proposed. A review of measuring equipment which employs the temperature-wave method is presented.

Background Currently, one of the causes of high morbidity and mortality is injuries. Predict the outcome of injuries - it is an important task of the treating physician. Trauma is a stress factor so to predict the outcome, you can use markers of stress, the most accessible ofwhich is blood glucose.to reveal the dynamics of the relationship between blood glucose levels and the outlook for the life ofpatients with thoracoabdominal injuries.A retrospective analysis of medical records of hospitalized patients were divided into two groups, depending on the outlook for the life of (favorable or unfavorable), and each of the groups - into two subgroups according to the presence or absence of signs of intoxication at admission. The subgroups were calculated and compared the mean blood glucose levels at different hours of hospital treatment.It was found that the average blood glucose levels at various hours of hospital stay were significantly higher in patients with poor outcome. The most noticeable was the difference in the first days of hospital treatment. Signs of intoxication was associated with lower values of glucose and a tendency to hypoglycaemia. In addition, among patients with high blood glucose ( 8 mg / dL) was observed over deaths in the first day of hospital stay.High blood glucose levels ( 8,0 mmol / L) in the first day of hospital treatment is a predictor ofpoor outcome in patients with thoracoabdominal injuries.

Creation of large-size reflectors for spacecrafts is a topical issue for the space industry. The accuracy of the reflecting surface form and the structure weight are the main criteria for the reflector design. The accuracy of the reflecting surface form during a long-term operation is provided by adjustment when using piezoelectric motors in the reflector design. These motors have small weight-size parameters and can reach great torque values. The piezo motor is a distributed mechanical-acoustic oscillation system. Mechanical-acoustic oscillations are generated in the piezo motor by a PZT-stack and transmitted to an oscillator element, and then from the oscillator element to a load action element. At high frequencies, when dimensions of the oscillator are proportionate to the wavelength, the energy is transmitted by means of acoustic waves. In this case, mechanical waves practically are not involved in the energy transmission process. This thesis shows a method for selecting the material of a mechanical-acoustic oscillation system according to the efficiency of the acoustic energy transmission via a piezoelectric layered structure.

The implementation of the Smart City system needs reliable and smoothly operating electronic equipment. The study is aimed at developing a nondestructive testing method for electronic equipment and its components. This method can be used to identify critical design defects of printed circuit boards (PCB) and to predict their service life, taking into account the nature of probable operating loads. The study uses an acoustic emission method to identify and localize critical design defects of printed circuit boards. Geometric dimensions of detected critical defects can be determined by the X-ray tomography method. Based on the results of the study, a method combining acoustic emission and X-ray tomography was developed for nondestructive testing of printed circuit boards. The stress-strain state of solder joints containing detected defects was analyzed. This paper gives an example of using the developed method for estimating the degree of damage to joints between PCB components and predicting the service life of the entire PCB.

An algorithm for the simulation modeling of the errors in measuring the properties of heat-insulating materials is developed, based on the use of a mathematical model of the temperature field in a plane sample of the material. A procedure for processing the experimental data is considered, and recommendations are made on the choice of the optimum conditions for using this procedure.

The article describes the development and experimental studies of microlinear piezo-drive for control reflective surface devices of large-sized transformable spacecraft antenna reflectors. Research target—experimental investigation of the microlinear piezo-drive to determine stable oscillatory system operating modes which would include improved energy conversion parameters. The following characteristics are briefly presented: test stand construction-design description, identification of oscillatory system resonant and actual frequencies under inertia load. A series of experiments have been conducted for both different preliminary tensions and inertia mass values.

The following work is connected with a new solution of aerospace focusing problem for communication systems. It is offered to use an inflatable spherical lens-reflector which can be calculated by Fresnel zone theory application. The antenna focus is situated on its external surface that is very important for applications.

This paper describes the solid-propellant rocket engine structure, including casing and filler. The gas flows within the filler channel. Based on numerical conjugate problem solution, non-stationary stress-strain states of the casing and filler were determined, as well as gas flow parameters in the channel. Within the conjugate problem, the engine is considered to be a two-component system: deformable solid body and gas. Conjugate problem solution involves specific subtasks related to the conjugation conditions, where Lagrangian approach is used for subtasks of solid body. Euler approach is used for subtasks of gas, implying immovable boundary of the computational domain on the integration time step. Numerical methods are applied in solving subtasks. Specific feature of conjugate problem solution algorithm is discrete movable domain boundary interface.

This paper describes the new method and the device for measuring the effective thermophysical characteristics of the investigated fluid under shear flow conditions at a fixed shear rate in the gap between coaxial cylinders. The shear flow is provided by the rotation of the outer cylinder while the inner cylinder remains stationary. The measuring unit can measure the complex rheological and thermophysical characteristics of liquids in less than 30 minutes. This article describes a two-step measurement method. The first step involves the measurement of the excess temperature established because of the heat source action due to the viscous friction in shear flow of the test liquid in a layer between the cylinders; the function of the dissipative heat source in the fluid at this stage is based on the power-law. The second step includes the thermal effect on the liquid layer from the heat source (electric heater) in the inner cylinder and the registration of the temperature response in the inner cylinder layer near the heater. The experimental determination results of polyoxyethylene solution thermophysical characteristics with the addition of nanocarbon material “Taunit” are presented here.

The article embraces the experimental description of the micro linear piezo drive intended for the peripheral cord tensioner in the reflecting surface shape regulator system for large-sized transformable spacecraft antenna reflectors. The research target is the experimental investigation of the micro linear piezo drive to determine the stable oscillatory system operating modes which would include improved energy conversion parameters. The following points are briefly presented: test stand construction-design of the peripheral cord tensioner; the determined frequency characteristics and the identified resonant and actual frequencies of an oscillatory system under inertia load. A series of experiments has been conducted for both different preliminary voltages and inertia mass values.

The solution of the tasks in the field of creating and processing materials for additive technologies requires the development of a single theory of materials for various applications and processes. A separate class of materials that are promising for use in additive technologies includes materials whose consolidation is ensured by the presence of low-melting components in the initial mixture which form a matrix at a temperature not exceeding the melting point, recrystallization or destruction of any of the responsible refractory components of the initial dispersion. The study of the contribution of the binder thermal destruction to the structure and phase composition of the initial compact of the future composite is essential for the development of modern technologies for the synthesis of low-temperature ceramics. This paper investigates the effect of the thermal destruction of a binder on the formation of a green compact of low-temperature ceramics and the structural-mechanical characteristics of sinter...

In designing sophisticated printed circuit boards, required evaluation of the product life cycle is relevant in terms of presumably applied load conditions during operation. The paper describes the durability evaluation method of printed circuit board components with contact output such as ball grid array (BGA) and pitch grid array (PGA) under thermal loads. Experiment data and numerical simulation results of soldered connections have been obtained. This method is demonstrated by a practical application example-evaluating of printed circuit board durability under cyclic thermal loads. The application of proposed method for printed circuit boards would make it possible to predict the service life of these designed products.In designing sophisticated printed circuit boards, required evaluation of the product life cycle is relevant in terms of presumably applied load conditions during operation. The paper describes the durability evaluation method of printed circuit board components with contact output such as ball grid array (BGA) and pitch grid array (PGA) under thermal loads. Experiment data and numerical simulation results of soldered connections have been obtained. This method is demonstrated by a practical application example-evaluating of printed circuit board durability under cyclic thermal loads. The application of proposed method for printed circuit boards would make it possible to predict the service life of these designed products.

This paper presents the buckling analysis of a new large-sized umbrella space reflector and its framework spoke members via finite element method. The main goal is to obtain critical load values for the reflector and its framework spoke members with corresponding buckling modes. In the context of considered method, linear and nonlinear approaches are used. To verify the linear analysis results for spoke the dynamic buckling analysis was applied, including the spoke first natural frequency decreasing under increasing axial loads. In the case of buckling this frequency equals zero. Additionally, according to reflector buckling analysis, it was proved that the safety factor for reflector framework structure is more than eight. Thus, this structure could be considered as reliable in view of buckling.

A mathematical model of the measurement errors is developed, which is used when determining the optimum operating parameters of the plane “instantaneous” heat source method, employed to measure the thermal diffusivity and volume heat capacity of heat-insulating materials.

A mathematical model of the measurement error is used when determining the optimal operating parameters of the regular mode method of the third kind, employed to measure the thermal diffusivity of thermal insulation materials.