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In modern technologies of pneumatic transport, fluidization, and polymer spraying, gas-dispersed media are widely used. Of particular interest, from the point of view of dynamic loading of structures, are shock-wave processes in gas-dispersed mixtures in the vicinity of the walls. The use of computer modeling methods makes it possible to reduce time and material costs for improving designs and optimizing technological process parameters. A hybrid large-particle method of second order approximation with a nonlinear correction, Superbee at the Eulerian stage and VanLeer at the Lagrangian stage, was used for the calculations. The algorithm is implemented as multi-threaded solver code, with processing of graphical results in a separate parallel process. A detailed numerical simulation of the characteristic stages of the interaction of a shock wave with a wall shielded by a layer of finely dispersed gas suspension with a cylindrical region of increased particle density was carried out. The beginning of the process (before the interaction of a plane shock wave passing into the layer of gas suspension with inhomogeneity) is one-dimensional in nature. Further development of the physical picture is associated with a significant restructuring of the flow. The shock wave enveloping the cylindrical boundary of the inhomogeneity converges to the plane of symmetry with the formation of a focusing effect. Due to baroclinic instability (mismatch of pressure and density gradients), a vortex zone is formed on the surface of the highdensity boundary. As shown by a detailed analysis of the calculation results, the most significant (more than an order of magnitude relative to the initial state) surges in pressure and density of the gas suspension are caused by the interactions of a focused shock wave that has passed into the inhomogeneity, and then an incident reflected composite shock wave pulse. The results obtained have theoretical and applied significance. New physical effects of shock wave reflection from a wall shielded by a layer of gas suspension with a cylindrical region of increased density of the dispersed fraction have been revealed. The reasons for the sequence of bursts in pressure and density of the mixture, which can lead to ignition and detonation of the combustible dispersed phase, are determined. The developed numerical algorithm and computer modeling technique can form the basis for the analysis of shock wave phenomena in the vicinity of the walls of structures and the justification of rational parameters of technological gas-powder technologies.

This article examines the utilization of computer simulation techniques for optimizing warehouse locations, an essential component of efficient supply chain management. The study employs a detailed simulation model built using FlexSim software to analyze various decision-making scenarios and identify the optimal warehouse locations while considering market demand for different products. The model integrates a finite set of decision variables and constraints specific to the logistics problem, offering a structured approach to evaluate alternative strategies. Key stages in the development of the simulation model are outlined, including the definition of input parameters, the execution of simulations, and the interpretation of results. The findings demonstrate that virtual simulation modeling significantly enhances decision-making processes by providing precise insights into the interactions within the distribution network. Additionally, the use of simulation results in considerable time and cost savings by reducing the need for costly physical trials. This research underscores the effectiveness of computer simulation in optimizing warehouse locations, contributing to improved supply chain performance and operational efficiency.

Introduction. Computer simulation and prototyping software can simplify the design process of complex information and measurement systems significantly, including radar systems and complexes. At present, a number of software packages are used to solve these problems to varying degrees. However, these software packages are either versatile, thus being incapable of taking the specifics of radar operation into account and requiring hand-made implementation of mathematical models for simulating radar signals, or are aimed at a narrow range of prototyping problems and algorithm development for processing radar information for a strictly defined radar type (or even a specific model). Some software packages, such as MATLAB, offer extension packages that allow radar signal simulation for automotive radars, as well as radar signal processing; however, these packages cannot cover the full range of simulation and prototyping tasks.Aim. Analysis of current software packages for simulation and prototyping of radar systems and complexes, justification of the demand and development of the concept and architecture of a software package for simulation and prototyping of radar systems and complexes.Materials and methods. Systems approach, architectural and conceptual software design, system analysis, criterion analysis. Results. The criteria that software packages for simulating and prototyping of radar systems and complexes must meet were determined. A comparative analysis of the existing approaches and software packages that solve problems arising at various stages of radar development was carried out. A list of requirements for such a software package was compiled, its concept and architecture was developed, and some features of its implementation were determined.Conclusion. The developed architecture allows creation of a versatile software package which could provide solutions to the problems of simulation and prototyping of radar systems and complexes using a single software package. The applied principles of modularity and decomposition ensure versatility and a high potential for adapting software modules, including for creating software for controlling radar prototypes and visualizing radar data in real time.

The article considers the development of a technological scheme for mining inclined deposits with an angle of incidence from 20 to 35 degrees on the example of the Zhilandy deposit using a chamber-column system. Deterioration of geomechanical conditions caused by incorrect parameters of the development system requires adjustment of these parameters. To solve this problem, modeling of the rock mass using the finite element method was carried out. As a result, the main compressive and tensile stresses were determined depending on the depth of working. The calculation of the parameters of the inter-chamber targets was also carried out taking into account various mining factors. The analysis of the numerical simulation results made it possible to determine the permissible parameters of the cleaning chamber and the inter-chamber whole depending on the angle of occurrence. It was found that the inter-chamber whole of the classical vertical shape is permissible only when the angle of incidence of the ore body is up to 25 degrees. A new technology for mining inclined deposits with an angle of incidence of 20-35 degrees using a chamber-column system was developed based on studies of the Zhilandy deposit. [ABSTRACT FROM AUTHOR]

Currently, the commissioning of power plants based on renewable energy sources (RES) using inverters is becoming widespread. However, these power plants do not participate in maintaining the stability of the power system during emergency disturbances, since they are switched off by technological protections when a disturbance occurs. In the future, when power plants based on renewable energy sources become widespread, ensuring the possibility of their participation in maintaining sustainability will significantly increase the reliability of the energy system. A preliminary assessment of the effectiveness of participation in maintaining sustainability should be carried out through computer modeling.THE PURPOSE: To realize the possibility of participation of RES-based power plants in ensuring reliable and sustainable operation of the power system, as well as to realize the possibility of performing a preliminary assessment of the effectiveness of the proposed method.METHODS. In this paper, the application of virtual synchronous generator technology is proposed to realize the possibility of participation of RES-based power plants in ensuring the reliability and sustainability of the power system. Also, a method of modeling the virtual synchronous generator in Matlab software package is proposed.RESULTS. The technology of virtual synchronous generator is proposed, which with the use of inverter, electric energy storage and appropriate control system can provide the increase of dynamic stability of power system. A method of modeling the virtual synchronous generator in Matlab software package is proposed. The results obtained allow us to conclude that the constructed model of a virtual synchronous generator is efficient, maintains the stability of the system and ensures correct control of the inverter, as a result of which the parameters of the electrical network are maintained within acceptable limits. The resulting computer model can be used in further research.CONCLUSION. The technology of virtual synchronous generator allows to imitate in the inverter the inertial and damping characteristics of the traditional synchronous generator, and the proposed computer model will help to evaluate the effectiveness of this technology when implemented in the power system.

Aim. Development of the method for designing electromagnetic hybrid active-passive shield, consisting from active and multy-circuit passive parts, which is characterized by increased effectiveness of reducing the industrial frequency magnetic field created by two-circuit overhead power lines in residential buildings. Methodology. The designing problem of electromagnetic hybrid active-passive shield including robust system of active shielding and multy-circuit passive shield of initial magnetic field comes down to a solution of the multy-criteria two-player zero-sum antagonistic game. The game payoff vector calculated based on the finite element calculations system COMSOL Muliphysics. The game solution calculated based on the particles multyswarm optimization algorithms. Results. During the design of the electromagnetic hybrid active-passive shield the coordinates of the spatial arrangement of 11 circuits passive shield and the coordinates of the spatial location of one compensation winding, as well as the current and phase in this winding of the active shielding system are calculated. The results of theoretical and experimental studies of hybrid active and multy-circuit passive shield by magnetic field in residential building from two-circuit power transmission line with a «Barrel» type arrangement of wires presented. Originality. For the first time the method for designing hybrid active and multy-circuit passive shield, consisting from active and multy-circuit passive parts, which is characterized by increased effectiveness of reducing the magnetic field of industrial frequency created by two-circuit overhead power lines in residential buildings is developed. Practical value. Based on results of calculated study the shielding efficiency of the initial magnetic field what is confirmed by experimental studies determined that shielding factors whith only multy-circuit passive shield is more 1.2 units, whith only active shield is more 4 units and with electromagnetic hybrid active-passive shield is more 6.2 units. It is shown the possibility to reduce the level of magnetic field induction in residential building from two-circuit power transmission line with a «Barrel» type arrangement of wires by means of electromagnetic hybrid active shielding with single compensating winding and multy-circuit passive shielding with 11 circuit passive shield to 0.5 μT level safe for the population. References 51, figures 17.

Aim. Development of the method of designing a combined electromagnetic shield, consisting of active and passive parts, to improve the effectiveness of reduction of industrial frequency magnetic field created by two-circuit overhead power lines in residential buildings. Methodology. The problem of design of combined electromagnetic shield including robust system of active shielding and electromagnetic passive shield of initial magnetic field solved based on of the multi-criteria two-player antagonistic game. The game payoff vector calculated based on the finite element calculations system COMSOL Muliphysics. The game solution calculated based on the particles multiswarm optimization algorithms. During the design of combined electromagnetic shields spatial location coordinates of shielding winding, the currents and phases in the shielding winding of active shielding, geometric dimensions and thickness of the electromagnetic passive shield are calculated. Results. The results of theoretical and experimental studies of combined electromagnetic passive and active shielding of magnetic field in residential building from power transmission line with a «Barrel» type arrangement of wires presented. Originality. For the first time the method of designing a combined electromagnetic shield, consisting of active and passive parts, for more effective reduction of the magnetic field of industrial frequency created by two-circuit overhead power lines in residential buildings is developed. Practical value. Based on results of calculated and experimental study the shielding efficiency of the initial magnetic field determined that shielding factors whith only electromagnetic passive shield is more 2 units, whith only active shield is more 4 units and with combined electromagnetic passive and active shield is more 10 units. It is shown the possibility to reduce the level of magnetic field induction in residential building from power transmission line with a «Barrel» type arrangement of wires by means of a combined electromagnetic passive and active shielding with single compensating winding to 0.5 μT level safe for the population. References 53, figures 15.

Aim. Development of method for design a two-level active shielding system for an industrial frequency magnetic field based on a quasi-static model of a magnetic field generated by power line wires and compensating windings of an active shielding system, including coarse open and precise closed control. Methodology. At the first level rough control of the magnetic field in open-loop form is carried out based on a quasi-static model of a magnetic field generated by power line wires and compensating windings of an active shielding system. This design calculated based on the finite element calculations system COMSOL Multiphysics. At the second level, a stabilizing accurate control of the magnetic field is implemented in the form of a dynamic closed system containing, in addition plant, also power amplifiers and measuring devices of the system. This design calculated based on the calculations system MATLAB. Results. The results of theoretical and experimental studies of optimal two-level active shielding system of magnetic field in residential building from power transmission line with a «Barrel» type arrangement of wires by means of active canceling with single compensating winding are presented. Originality. For the first time, the method for design a two-level active shielding system for an power frequency magnetic field based on a quasi-static model of a magnetic field generated by power line wires and compensating windings of an active shielding system, including coarse open and precise closed control is developed. Practical value. It is shown the possibility to reduce the level of magnetic field induction in residential building from power transmission line with a «Barrel» type arrangement of wires by means of active canceling with single compensating winding with initial induction of 3.5 µT to a safe level for the population adopted in Europe with an induction of 0.5 µT.

The purpose of the work is to develop a synthesis method for the spatial and angular arrangement of magnetic field sensors in order to ensure maximum efficiency of a robust system for active shielding of the magnetic field generated by overhead power lines, and to reduce the sensitivity of the synthesized system to initial uncertainties in changes in the level of the initial magnetic field, as well as system parameters while working. To achieve this goal, the spatial location coordinates and angular position of all magnetic field sensors, controller parameters, and gain vector for the compensating windings are determined. A synthesis of the spatial location and angular position of magnetic field sensors is created to solve a minimax vector optimization problem in which the vector objective function is calculated based on the Biot-Savart’s law. Solution of the minimax vector optimization problem, calculated on the basis of optimization algorithms for a multi-swarm of particles from Pareto-optimal solutions, taking into account the parameters of binary relations. Significant results obtained on the basis of the developed synthesis method are the effectiveness of a robust active shielding system for magnetic fields generated, as a consequence, by power lines with a synthesized spatial arrangement and angular position of magnetic field sensors obtained in the process of theoretical and experimental research. The significance of the results lies in the fact that practical recommendations are given for the reasonable choice of spatial location and angular position of magnetic field sensors, the spatial arrangement of shielding windings of a robust magnetic field shielding system for various characteristics of power lines.

Introduction. Modern chemotherapy widely considers the role of antioxidant and pro-oxidant methods in the treatment of oncologic pathologies. The use of agents that cause an increase of ROS is a relevant way to destroy tumors. At the same time, there is evidence of the ability of some antioxidants to lead to the cancer cells apoptosis through the generation of free radical forms of oxygen due to disruption of cellular homeostasis. The combination of the «Ecolum» biosensor using technique, antiradical activity data, and information about the cytotoxicity of compounds used in the study allows us to consistently conduct low-cost screening of as antioxidant, as antiradical activities and potentially reduce the required number of expensive cytotoxicity determinations using tumor cells.Aim. The main target of our work is the evaluation of antioxidant and cytotoxic activities of 1,3-dioxolane derivatives of imidazole using antioxidant, antiradical and cytotoxicity tests in vitro.Materials and methods. To carry out this study, 1,3-dioxolane derivatives of imidazole were obtained. The antiradical tests was performed using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method. Antioxidant properties were assessed within the Ecolum biosensor in the state of oxidative stress. Cytotoxic activity was assessed in GIST-T1 cell culture using the MTT test (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide).Results and discussion. Data from studies of the antioxidant activity of substances using the «Ecolum» biosensor showed varying degrees of damage to the biosensor in the absence of antioxidant action. The antiradical potential, initially used to reveal a possible mechanism of antioxidant action, actually demonstrated a possible mechanism of toxic action of substance 2c due to its antiradical effect comparable to the standard (Trolox), but the substance has the highest cytotoxicity. However, the properties of substance 2a shows that the direct correlation discussed earlier is not found in all cases.Conclusion. The asessment of the antioxidant properties and cytotoxic activity of 1,3-dioxolane derivatives of imidazole demonstrated the relevance of further searching for connections between the results of substances binding with the Ecolum biosensor under conditions of oxidative stress, their antiradical potential and cytotoxic properties. This combination of tests will potentially reduce the cost of screening through the use of an available biosensor, establish a possible mechanism of action aimed at redox balance, and confirm previously obtained data through the use of tumor cell culture.

The magnitude of the localized surface plasmon resonance (LSPR) in metal nanoparticles is determined by many factors. Thus, with an increase in their average linear size, the maximum position of the LSPR peak shifts towards long waves. However, the position of the LSPR maximum is affected to a greater extent by the material of the nanoparticles. Changing the average particle diameter from D = 7 nm to D = 60 nm makes it possible to vary the position of the LSPR maximum in the range of about 50 nm. However, with a smooth change in the composition of binary nanoparticles, it can already be varied within about 120 nm. Therefore, copper-silver alloy nanoparticles are of great practical interest due to the possibility of fine-tuning the plasmonic effects present in them by changing the composition, size, shape, and structure of the nanoparticles. Based on the results of the analysis of the available experimental data, it was concluded that it is possible to control the internal structure and shape of Ag-Cu nanoparticles in order to shift the plasmon resonance peak and enhance it.

Silver is one of the most promising nanomaterials for plasmonic applications due to its low cost as well as the ease with which it can be prepared into nanoparticles with controlled size and shape. By now, it has already become clear that it is the shape and internal symmetry of nanoparticles that can significantly affect the scattering and absorption of a light wave, since without the formation of a strong dipole, these effects in nanoparticles will be insignificant. Therefore, the main objective of the study was a theoretical analysis of the processes of formation of the external and internal structure of silver nanoclusters obtained by some methods of physical synthesis. To do this, we studied high-resolution electron microscopy data for the initial and annealed silver nanoparticles formed on a carbon substrate by vacuum thermal evaporation and having sizes from 2,0 to 10,0 nm. It has been established that, as a result of annealing, the number of small nanoparticles (D< 3,5 nm) decreases by approximately 2 times, and the proportion of nanoparticles with icosahedral and decahedral faceting increases by approximately 1,5 times. Based on the analysis performed, conclusions were drawn about the possible features and mechanisms of formation of various types of symmetry in synthesized Ag nanoparticles.

In the production of SERS (surface enhanced Raman scattering) substrates, two main approaches to the formation of an array of plasmonic nanoparticles are used: photolithography and chemical methods. Each of them has its own advantages and disadvantages. Vacuum thermal evaporation can also be used. It was chosen for analysis by computer simulation. For this, molecular dynamics simulation of the processes of crystallization of an array of binary Ag-Au nanoparticles was used, which makes it possible to smoothly control the plasmon resonance wavelength. Three arrays of Ag-Au NPs with a diameter of 2,0; 4,0 and 6,0 nm of various target compositions from Ag90Au10 to Ag50Au50 were created. They were subjected to the procedure of cooling from the melt with different rates of the thermal energy removal. In the course of modeling the formation of the internal structure of Ag-Au nanoparticles, conclusions were drawn about the dependence of these processes on the target composition, size, and level of thermal exposure. Based on the regularities obtained, adjustments were made to the technological process of creating SERS substrates using binary Ag-Au nanoparticles.

Phase-change random access memory is an excellent candidate for next-generation non-volatile memory technology. In order to meet the needs of the industry, its capacity must be improved, for which it is necessary to reduce the volume of a unit cell. Proceeding from this, in this work, the possibility of using nanoparticles of the Ag-Au binary alloy as individual phase-change random access memory cells was evaluated by computer simulation. The method of molecular dynamics with a modified tight binding potential was used. For this, an analysis was made of the crystallization processes of these nanoparticles with a diameter of 2,0 to 8,0 nm with different rates of thermal energy removal. It was shown that the addition of gold to the composition makes it possible to solve the problem of the complex reproduction of the amorphous structure, which is characteristic of pure Ag nanoparticles. Due to this, stable switching between the amorphous and crystalline phases can be achieved at a nanocluster diameter of ≥4 nm and ≥6 nm with an Au content in the composition of ≥40% and ≥20%, respectively, which is significantly lower than the cut-off value of 10 nm characteristic of silver nanoparticles.

In this work, computer simulation of the processes of formation of the internal structure of plasmonic Ag-Cu nanoparticles was carried out. Method of molecular dynamics based on the tight binding potential was used. The crystallization of Ag-Cu nanoparticles with a diameter of 2,0-8,0 nm with an atomic copper content ranging from 10 to 50% was simulated. To remove thermal energy, an Andersen thermostat was used with three different cooling rates ΔT/Δt = 30∙1011, 12∙1011, 5∙1011 K/s. The possible structural transitions arising in this case were determined using the radial distribution function and the change in potential energy. To determine the most stable cluster structure, an ensemble of nanoparticles of the same size was taken. Then, using the visualizers OVITO and xmakemol, the real appearance and structure of the studied nanoparticles were found. In the course of the simulation, it was found that at low levels of copper doping in Ag-Cu nanoparticles, the formation of five-particle symmetry is possible. The conditions for the occurrence of this effect were fixed. It was also determined that D = 8,0 nm for Ag-Cu nanoparticles is the size limit, starting from which the macroscopic effect of stabilizing the fcc structure of the eutectic alloy appears under the condition of very fast sample quenching.

The results of the development of a high-voltage semiconductor voltage generator (based on IGBT transistors) with a pulse transformer and the results of experiments on generating a capillary discharge using it on a compact gas-discharge source capable of generating pulses of soft X-ray radiation (SXR) in the area of the socalled «water window» - with wavelength in the range of 2.4...4.4 nm. Methods for designing a high-voltage pulse voltage pulse generator are described: theoretical calculations and results of modeling the electrical circuit diagram in the LTSpice software package, the developed design of a pulse transformer based on N87 ring ferrites and the generator itself is described, the results of its operation as part of a compact gas-discharge radiation source are presented and analyzed. The prospects of using such a high-voltage generator (with semiconductor transistor switches) with a pulse transformer as part of a soft X-ray radiation source are shown due to its technical and operational features: the developed generator is capable of operating from an alternating current network of 380 V/50 Hz in a frequency-burst mode (with a repetition rate of the generated voltage pulses up to 600 Hz) and charges the capillary capacitance of the SXR source to a voltage of more than 20 kV in a time of about 4 μs, has small dimensions, does not create pulsed high-frequency interference and false alarms, and also has stable output (amplitude-temporary) parameters.

В статье приводятся результаты компьютерного моделирования распространения плоской электромагнитной волны. Грозовые разряды являются естественными источниками импульсного электромагнитного излучения (атмосферика). Атмосферик распространяется в волноводе Земля-Ионосфера как плоская электромагнитная волна с широким спектром частот с максимумом интенсивности в диапазоне 4-10 кГц. После землетрясений с магнитудами порядка 7 и более, увеличивается насыщенность подземных вод вторичными минералами, что приводит к локальному увеличению проводимости земли в данных областях. Что определяет электрофизические свойства земли, как параметры нижней границы волновода Земля-Ионосфера. Которые влияют на характеристики распространяющихся в волноводе электромагнитных волн. Предполагается, что, изучая параметры атмосферика можно установить наличие неоднородности проводимости стенки волновода. На основе системы уравнений Максвелла с краевыми условиями в виде Perfectly matched layer, задаётся математическая модель процесса. Краевые условия модели определяют область распространения электромагнитного широкополосного сигнала, как волновод с неоднородной проводимостью границ. Система модельных уравнений решается численным методом Finite-Difference Time-domain. Для решения поставленной задачи и проведения компьютерного моделирования разработан программный комплекс в среде MATLAB. С целью проверки предположения, был проведён ряд компьютерных симуляций. В результате показано, что имеет место обратное рассеяние электромагнитной волны на трассе волновода, возникающее в следствии отражения волны при её взаимодействии с неоднородностью проводимости нижней границы волновода. Показано, что с помощью математического моделирования процесса распространения атмосферика и его взаимодействий с неоднородностью в волноводе можно установить наличие неоднородности и её связь с характеристиками излучения.

In the search for new magnetically ordered phases of materials, solid-state synthesis technologies in reaction crucibles are used. The final result of the synthesis process in reaction crucibles is conditioned, in particular, by technological factors, the mode of current flow and its density, the achieved temperature in the reaction zone, exposure time, geometrical parameters of the crucible and the reaction zone, etc. The paper presents the results of influence investigation of the reaction volume filling degree with tin melt on the processes of heat and mass transfer during its electrothermal treatment. A model describing diffusion processes in the reaction zone during the synthesis of iron and tin intermetallides under electrothermal treatment has been proposed. The diffusion process in the reaction crucibles of the iron-tin system was investigated by the finite element method in the Comsol Multiphysics software environment. It is shown that the decrease in the degree of filling of the reaction crucible with synthesis components leads to a change in the distribution of current density and a decrease in the temperature in the reaction zone, which affects the mass transfer processes. The results of the work can be used in the analysis of experimental data on the production of intermetallides by reaction synthesis and determination of the necessary technological parameters for the synthesis of new materials.

Introduction. The author examines the problem of improving the accuracy of computer simulation of electromagnetic processes of an auxiliary asynchronous motor of an electric locomotive with the frequency adjusted by an autonomous voltage inverter. The calculations of instantaneous motor phase currents were improved. The research justified the proposed adjustments to the computer model of a three-phase asynchronous motor to consider the skin effect in the stator and rotor windings, and the effect of the magnetic circuit saturation from leakage fluxes on the leakage inductance of the phases and, thereby, on the instantaneous phase currents. The model is necessary to enhance the reliability of the auxiliary electric drive of an electric locomotive through the correct selection of semiconductor switches for the electric motor inverter. Materials and methods. The researcher chose computer simulation using OrCAD as our research method, and the input data include experimental instantaneous phase voltages of the auxiliary asynchronous motor.Results. The article presents the results of adjusted computer simulations of instantaneous variables for steady-state engine operation and compares them with experimental data.Discussion and conclusion. The author compared the experimental and calculated data (phase current, torque, rotation speed of the auxiliary asynchronous motor of an electric locomotive) and substantiated the adjusted computer model to reduce errors in the calculation of electromagnetic processes of the electric motor. The adjusted computer model improves the accuracy of calculating the instantaneous phase currents of the motor. The calculations were performed for the steady-state operation of an asynchronous motor of the AZhV250M2RUHL2 type. The results show that the skin effect has the greatest influence on the leakage inductance of the stator winding.

Introduction. Recently, more extensive use of steel-reinforced concrete (steel-concrete) structures is planned in civil buildings. In steel-reinforced concrete ceilings. The use of bent profiles in steel-reinforced concrete bent structures has not yet become widespread, probably due to the lack of simple methods. Therefore, the study of the stress-strain state of steel-reinforced concrete beams is a very urgent task. The article presents a new methodology and calculation formulas for assessing the bearing capacity of bent steel concrete elements reinforced with a cold-formed profile. Computer models of a composite beam consisting of bent profiles embedded in concrete are described, where options for the location of anchor ties are considered, which ensure the joint operation of both the profile with concrete and two bent channels into an I-beam. On the basis of the results of numerical studies, models of beams were made and tested. Analysis of the stress-strain state of experimental beams, their behavior under the influence of increasing the degree of increase in the intensity of development of the abilities of beams based on the limiting relative deformations of the personality of concrete. The results of experimental studies are presented in the form of graphs, comparison of the results of a full-scale experiment and numerical studies using computer models, as well as using analytical formulas. In conclusion, comparisons of the results of full-scale tests with numerical studies and by analytical formulas are given.Materials and methods. The ANSYS software package was used for computer simulation. Analytical formulas for assessing the strength of a bending element are written on the basis of the limiting relative compressive strains of concrete. For full-scale experiments, composite steel beams were made, consisting of bent channels with filling the side cavities with concrete, self-tapping screws were used as anchor connections.Results. The stress-strain state of the beams was revealed according to the obtained dependences and as a result of full-scale tests, as well as on the basis of computer simulation. The results of numerical studies are used for the manufacture of full-scale samples. The results of numerical values according to the proposed analytical formulas are compared with the data of full-scale experiments.Conclusions. Analytical dependences of the strength assessment of reinforced concrete bending elements by the method based on the limiting relative deformations of concrete compression are proposed, the features of the operation of reinforced concrete beams are studied by numerical modeling and by analytical dependences, full-scale experiments. It is shown that numerical studies give good convergence with experimental data. Analytical dependencies recorded on the basis of the ultimate relative compressive strains of concrete give better results than the well-known calculation method based on the limit force method.

Introduction. In view of the ever-tightening bandwidth requirements for wireless communication systems, the use of tunable or switching devices based on microwave keys is becoming increasingly popular. Currently, the development of microwave keys based on nonlinear materials, such as vanadium dioxide, is a relevant research direction. The keys based on this material are distinguished by a planar and simple design, thus being suitable for creating microwave devices using hybrid technology.Aim. To study the properties of thin vanadium dioxide films and to develop a microwave switch with electrical switching on their basis.Materials and methods. Experimental samples of thin vanadium dioxide films were obtained by magnetron sputtering. The phase transition parameters of the samples obtained experimentally were used in computer simulation of a planar two-electrode structure of a microwave key by the finite element method.Results. Experimental samples of vanadium dioxide films were manufactured, and the dependences of their resistivity on temperature were studied. The resistance of the obtained vanadium dioxide films was found to change threefold. A microwave key design based on vanadium dioxide films was developed. The formation of a currentconducting channel in vanadium dioxide films was simulated when a control voltage was applied. The threshold voltage of the element was estimated depending on its design parameters.Conclusion. The use of experimental data as a basis for computer simulation made it possible to determine the threshold values of currents depending on the topology and design of the proposed microwave key. The results of simulating the key structure showed the formed conductive channel to have clearly defined boundaries in terms of distribution of both current density and temperature across the film surface.

Introduction. The authors analyse the influence of the design features of crossings with a solid core unit with wing rails and welded rail ends (monoblock crossing) on the occurrence of hazardous failures associated with design flaws. Stress distribution to ensure uniform stiffness and avoid dangerous failures while ensuring product manufacturability is an important issue in cross design. This is achieved by rationalising the casting's longitudinal force element.Materials and methods. A computer simulation using ANSYS finite element analysis is used to determine the influence of the location of the force element in a monoblock crossing design on the fatigue safety factor. Operational tests of the prototype crossings were carried out on the second main track of the Experimental Loop of Railway Research Institute and at the Isilkul station of the West Siberian Railway.Results. The influence of the geometry of the longitudinal rib of the crossing and its location on the failure-free operation of the structure is studied. Based on the calculation results and confirmed tests, the final geometric dimensions of the one- piece core unit with wing rails are proposed, taking into account product manufacturability. Recommendations are given for the positioning of the longitudinal ribs of the monoblock crossings during the design phase. The proposed design of the monoblock crossings is adopted for series production.Discussion and conclusion. The lowest equivalent stresses are found in one of the monoblock crossing designs with two longitudinal stiffening ribs presented in the article. This design allows the product to operate in a way that prevents dangerous failures. The implementation of the principles of mathematical modelling used in this work, taking into account the adopted calculation scheme, ensures a significant reduction in the time required for the design and manufacture of crossings with a solid core unit with wing rails and welded rail ends.

Background and Objectives: Metasurfaces are coatings consisting of elementary resonators that reemit incident UHF electromagnetic waves. By varying the parameters and arrangement of these resonators, it is possible to tune the electrical properties of the metasurface as a whole. This produces a number of practically important characteristics that are difficult to achieve with conventional attenuation coatings, and therefore prospective in the tasks of shielding of electronic devices and attenuation of the reflected signal. As there are many possible configurations of resonators, numerical experiments are needed for an effective comparative analysis. We investigate metasurfaces consisting of rectangular stripline resonators arranged on a dielectric substrate in a checkerboard pattern in two configurations. The aim of the study is to obtain scattering diagrams in numerical experiments and compare them with real structures. Materials and Methods: In this paper a computer simulation of the interaction of metasurfaces with the microwave radiation in open space is carried out using the CST Studio package with a time domain solver. Calculations were performed for several frequencies in the range of 16 to 25 GHz. Experiments were then carried out with real structures at the same frequencies, using a bistatic method of measurements. The structures, with single resonators measuring 2×4.2 mm matching the frequency range, consisted of etched copper-plated FR4 sheets overlaid on a metal plate. Results: The results show that the value of the normal component of the reflected electromagnetic wave decreases as the incident frequency approaches the resonance frequency. Also, side lobes, with a frequency-dependent magnitude, are observed. The scattering diagrams obtained with real samples show the same characteristic features with differences caused by physical particularities of the receiving antenna as well as the presence of diffraction effects. Both structures examined have shown high incident wave scattering, which is clearly indicated by the redistribution of the central lobe in diagrams. Comparison has shown that the simulated metasurfaces have similar patterns to the experimental diagrams. Conclusion: The comparative analysis has demonstrated a satisfactory fit of the simulation to the experiment. Further studies with structures of this type are planned in the future. It may be noted that the CST Studio package has worked well and will be used in future studies.

The paper presents tasks and approaches to their solutions in assessing vibration strength and dynamic safety of marine reactor equipment (for example: pumps, control driven rod mechanisms). The topicality of this work is determined by the experience of operating nuclear power plants. Development of digital computation models and computational analysis allowed us to exclude experimental validation of control driven rod mechanisms seismic resistance. A digital computational model was developed for validating the dynamic safety and life time of the seal pot of the reactor facility main circulation pump. The model included the main circulation pump and the framework of the reactor facility. Computational and experimental analysis of the vibration state of the control and protection system drives was also carried out.

The authors present the results of modeling the temperature drift of the resonator path length of a laser gyroscope based on a ring helium-neon laser with circular polarization of radiation and a magneto-optical frequency bias based on the Zeeman effect using the MATLAB mathematical package. The algorithm developed and implemented in the MATLAB environment makes it possible to simulate temperature deformations of the path length of a Zeeman laser gyroscope when the configuration of its structural elements changes. This allows to evaluate the quality of the supplied material for the manufacture of the ring laser resonator, as well as to evaluate the total contribution of structural elements to the resulting drift of the perimeter of the Zeeman gyroscope. The model obtained in the work is an analytical tool for additional quality control of the optical glass-ceramic SO-115M, from which the resonator is made, and optimization of the design of the Zeeman laser gyroscope, both locally and comprehensively. This is necessary to increase the efficiency of ring laser perimeter stabilization in the operating temperature range using an active perimeter adjustment system and passive thermal compensation by selecting structural elements with opposite temperature coefficients of linear expansion. The use of the developed model in the production of laser gyroscopes permits to select the structural elements of the Zeeman gyroscope, which significantly increases the time of its continuous operation in a single-mode in a wide temperature range while maintaining the re-quired accuracy for the orientation, stabilization and navigation systems of various aircraft.

Aim. Development of a method for optimization of spatial arrangement and angular position of magnetic field sensors of a closed system to ensure maximum efficiency of active silencing canceling of the magnetic field generated by overhead power lines. Methodology. Spatial arrangement and angular position of magnetic field sensors of closed loop system of overhead power lines magnetic field active silencing determined based on binary preference relations of local objective for multi-objective minimax optimization problem, in whith the vector objective function calculated based on Biot–Savart law. The solution of this vector minimax optimization problem calculated based on nonlinear Archimedes algorithm of multi-swarm multi-agent optimization. Results. Results of simulation and experimental research of optimal spatial arrangement and angular position of magnetic field sensors of a closed system to ensure maximum efficiency of active silencing of the magnetic field generated by overhead power lines with a barrel-type arrangement of wires. Originality. The method for optimization of spatial arrangement and angular position of magnetic field sensors of a closed system to ensure maximum efficiency of active shielding of the magnetic field generated by overhead power lines is developed. Practical value. An important practical problem optimization of spatial arrangement and angular position of magnetic field sensors of a closed system to ensure maximum efficiency of active silencing of the magnetic field generated by overhead power lines has been solved.

The aim of the study is to create a virtual test bench, consisting of optimal design parameters that provide the maximum approximation of the real drying process to the experimental data.Method. Methods of modeling, formalized description, optimal design and management of technological processes and productions are applied. Result. A virtual test bench has been developed that allows real-time determination of the design parameters of drum-type dryers depending on the kinetic patterns of the drying process of various grain crops. As an object of study, the design of a two-section drum dryer was used, each section of which is equipped with a profile channel nozzle that provides a transverse supply of the drying agent through the pouring movable layer of the dispersed product to be dried. An algorithm for calculating the drying process is presented, which makes it possible to determine the fields of temperature and moisture content of grain in a wide range of regime parameters. With the use of CAD, a computer model of this installation was made with the possibility of autonomous rotation and movement of the drums relative to each other. A diagram of the synchronized operation of the moving elements of the installation under conditions of operational reconfiguration of its design in accordance with changes in the kinetic curves has been drawn up.Conclusion. The presented virtual test stand adequately and with high accuracy allows simulating the process of drying materials in a drum dryer; allows you to test the operation of a drum dryer at the development stage, conduct experiments with the highest possible accuracy, select the optimal drying modes for various materials with minimal energy consumption.

The aim of the study was to develop and validate a software package (SP) for computer simulation of the procedure for examining patients with lung cancer by SPECT/CT and assessing the accuracy of reconstruction of tumor lesions.Material and Methods. Lung scintigraphy for a patient with peripheral squamous cell carcinoma of the upper lobe of the right lung was performed using a two-detector gamma camera GE Discovery NM/CT 670 DR (USA) with high-resolution collimators for an energy of 140 KeV and a radiopharmaceutical (RP) 99mTc-Technetril (MIBI, Diamed, Moscow). The data obtained were subjected to computer processing using a specialized Xeleris 4.0 system from GE (USA). The SP included a program for generating a voxel phantom (“virtual patient”), a program for modeling the “raw” data acquisition (“virtual tomograph”) and an image reconstruction based on the OSEM algorithm (Ordered Subset Expectation Maximization). In order to validate the created SP, computer simulation of the above clinical case was performed. The semi-quantitative comparative image analysis was based on a tumor/background score.Results. There was a good correlation between clinical “raw” data recorded from a real patient and projection data calculated by the Monte Carlo method from a “virtual patient”. The results of the comparative analysis showed that the tumor/background assessment was underestimated in the reconstructed images.Conclusion. The problem of the accuracy of the tumor lesions reconstruction by using standard OSEM reconstruction algorithms has not been studied. This issue is important in the management of patients with tumor lesions of the lungs and requires study and systematization. The SP will be used in further studies to analyze errors and artifacts in images of tumor lesions, as well as to develop approaches to overcome them.

An important direction of modern pharmaceutical science is the creation of promising biologically active compounds, which in the hands of scientists can be transformed into effective medicinal products. Heterocyclic compounds are the undisputed leader in solving this problem. A well-known fact and a well-founded approach to achieving the desired pharmacological effect is the combination of different heterocyclic fragments in the structure of one molecule. And here it makes sense to focus our attention on such heterocycles as pyrazole and 1,2,4-triazole. After all, a number of well-known medicines have already been invented on their basis. Thus, the construction of a chemical tandem with heterocyclic blocks of the specified nature is an actual and promising direction of scientific work. The aim of the work was to create a number of S-alkyl derivatives of 4-amino-5-(5-(3-fluorophenyl)pyrazol-3-yl)-1,2,4-triazole-3-thiol and study their properties, as well as preliminary selective establishment biological potential of these compounds. Materials and methods. The synthesis of the target products of chemical transformation was successfully implemented by the step-by-step use of well-known methods of organic synthesis. Thus, the first stage was successfully implemented with the help of available reagents, the role of which was performed by diethyl oxalate and 1-(3-fluorophenyl)ethan-1-one with the participation of sodium methylate. The next stage involved hydrazinolysis. Subsequently, the corresponding potassium xanthogenate was successfully synthesized, which was subsequently transformed under the action of hydrazine hydrate into the target 4-amino-5-(5-(3-fluorophenyl)pyrazol-3-yl)-1,2,4-triazole-3-thiol. The next stage was S-alkylation. The structure of all synthesized substances was determined with IR spectrophotometry, 1H NMR spectroscopy, and elemental analysis. The individuality of the compounds was confirmed by high-performance liquid chromatography-mass spectrometry. In silico studies were carried out with well-known software products, namely: AutoDock Vina, Biovia Discovery Studio, Hyper Chem 7.5, and Open Babel. Cyclooxygenase-2, lanosterol 14α-demethylase, and anaplastic lymphoma kinase were used as model enzymes. Results. The optimal conditions for the stepwise creation of S-alkyl derivatives of 4-amino-5-(5-(3-fluorophenyl)pyrazol-3-yl)-1,2,4-triazole-3-thiol were established and the preparation of the specified compounds was carried out. The use of molecular docking made it possible to determine the perspective of further research on anti-inflammatory, antifungal, and antitumor properties in a number of synthesized structures. Conclusions. S-alkyl derivatives of 4-amino-5-(5-(3-fluorophenyl)pyrazol-3-yl)-1,2,4-triazole-3-thiol are reasonably promising objects for the study of antifungal activity.

The digitalization of the economy reduces the cost of doing business by automating the relevant processes, but any transformation creates new risks and economic instability. Economic instability leads to a drop in the standard of living and, as a result, negatively affects the activities of trade enterprises. Small and medium businesses are especially sensitive to any changes. The decrease in demand for most everyday goods has a painful effect on the activities of small and medium-sized businesses and leads to the emergence of new risks. These risks have a significant impact on reducing the profitability of enterprises. Therefore, it is important for each enterprise to diversify the activities of the enterprise, which includes the expansion of the product range, the reorientation of sales markets and the optimal distribution of goods between divisions of one enterprise.The subject of the article is multi-criteria models of a diversified portfolio that minimize the risks that arise in the era of the digital economy when managing retail chains. To formalize the problem, five models are proposed that differ in vector objective functions, both in the quantity and quality of the selected criteria. The aim of the work is to analyze the problem of choosing criteria in the corresponding multicriteria or vector diversification problems. The article examines the advantages of introducing an additional criterion of entropy maximization into the criteria of the classical two-criteria model of portfolio theory, which characterizes the degree of diversity of the portfolio composition. A complex combination of methods of classical portfolio theory and multicriteria optimization is applied. The results include a comparison of three methods for solving the following problems: criteria convolution, successive concessions, and computer simulation of the Pareto set. Conclusions: the results obtained will be useful for automating the risk management of retail chains. The practical value is that the obtained results of real data for the network have demonstrated the possibility of using the developed tool for automatic allocation of resources in the form of pareto-optimal portfolios in order to minimize risks.

Aim. Development the method of multi-objective parametric design for robust system of active canceling of magnetic field based on binary preference relations of local objective for multi-objective minimax optimization problem. Methodology. Spatial location coordinates of the compensating winding and the current in the shielding winding were determined during the preference-based multi-objective parametric design of systems of active canceling based on solution of the vector minimax optimization, in whith the vector objective function calculated based on Biot-Savart's law. The solution of this vector minimax optimization problem calculated based on nonlinear Archimedes algorithm. Components of Jacobi matrix and Hesse matrix calculated based on multi-swarm multi-agent optimization. Results. Theoretically and experimentally confirmed the effectiveness of reducing the level of the magnetic field in residential multy-storey old building of a double-circuit overhead power transmission lines with a barrel-type arrangement of wires by means of active shielding with two compensation winding. Originality. The method of multi-objective parametric design for robust system of active canceling of magnetic field based on binary preference relations of local objective for multi-objective minimax optimization problem is developed. Practical value. It is shown the possibility to reduce the level of magnetic field in residential multy-storey old building closed to double-circuit overhead power transmission lines with a barrel-type arrangement of wires by means of system of active canceling with two canceling winding to a level safe for the population with an induction of 0.5 μT.

Satellite communication systems have an advantage over other communication systems, as they have a large coverage of the territory. The Earth station can be located anywhere in this territory and can be either a legitimate user or a satellite pirate (an illegitimate user). The developers are faced with the task of determining the coordinates of an illegitimate user illegally occupying a frequency resource. The article proposes a block diagram of a signal filtering device, which is part of a device for determining the coordinates of an illegitimate user, a monitoring Earth station. The purpose, requirements and main task of each composite block of the filtration device are defined. The search and analysis of analog filters and signal filtering methods was carried out. In the MatLab Simulink software environment, a computer model of a signal filtering device has been developed according to a block diagram with the possibility of determining the phase run, as well as the settings of the filtering device blocks are disclosed, which can be adjusted during the study of the model. For the bandpass filters included in the filtering device, the phase frequency characteristics of the phase change of the received signal on the frequency of this signal are constructed. A phase lock loop system has been formed with the possibility of changing its parameters. Calculations of the phase incursion through the elements of the filtration device are made.

The diffusion processes regularity in the reaction crucibles of the iron-tin system during their electrothermal treatment was studied by the numerical simulation methods. The effect of current density and temperature on the processes of heat and mass transfer in the reaction zone has been studied. Numerical simulation was performed by the finite element method. The developed model includes mechanical, thermal, electrical and chemical processes during the electrothermal treatment of the iron-tin system in the reaction crucible, taking into account the distribution of components under various processing conditions of the reaction crucible. A comparative analysis of the calculated data on the diffusion of tin into iron under conditions of long-term exposure to high temperatures without the application of an electric voltage and when the reaction zone is heated by passing a high-density electric current is performed. A picture of the distribution of mass fractions of components depending on the type of impact is obtained. The penetration depth of the interacting components was determined and the intensity of the mass transfer processes was assessed. The regularities of heat and mass transfer in the system of iron and tin with a change of the process initial parameters are established. The model was verified by comparing the simulation results with the data of full-scale experiments on control samples. The research results can be used to predict the conditions for obtaining new functional materials.

A significant part of the research on the effectiveness of various systems is devoted to the study of their functioning in a stationary mode. However, from the point of view of their practical application, it is of interest to study the functioning of such systems with varying workload intensity in transient, non-stationary modes of operation. And unlike the models for studying non-stationary systems, which are essentially based on the static values of distributions, this paper proposes a model using arbitrary probability distributions over time. The mathematical formalization of the model is based not on the application of the classical differential model in the time domain, but on the formal representation of the probabilities of the system states in the Laplace transform, i.e., in a complex way. Determining the values of the probabilities of the systems states is based on the principle of balance of “complex probabilities” which allows developing models of nonstationary queuing systems with arbitrary probability distributions of the arrival time of requests and their service, taking into account random or deterministic time delays. For the operational calculation of systems, it is proposed to use the developed application with a graphical user interface. The architecture of this application is presented in the form of a package diagram. The algorithm of the application is shown. Comparison of the application operation with programs MATLAB and MathCad for solving the problems of technical calculations was made when modeling the process of functioning of the standard unit of quantity and the robot control system. The advantages of using the developed application are given. The presented results can be applied by specialists involved in research on the effectiveness of various systems.

Problem. The development of automotive technology for various purposes and the improvement of existing car models, requires a fast and flexible design process. Spatial models of details and nodes are the starting points for design, and the necessary design documentation is performed on their basis. When manufacturing parts on CNC machines, it is necessary to quickly obtain a control program that will increase the accuracy of the product by ensuring the optimal trajectory of the mutual movement of the part and the tool. Therefore, the creation of a comprehensive methodology for the design of car parts, their basic inspection and obtaining design documentation is an important technical task. Goal. The main goal of the work is to determine the rational sequence and basic principles of computer-aided design, research and manufacturing of car and engine parts, and the development of mathematical spatial models of surfaces in order to optimize control programs for CNC machines. Methodology. The approaches adopted in the work for solving the set goal are based on general design principles. The methods of conducting static and dynamic calculations, as well as spatial mathematical modeling of the processes of manufacturing parts were also used. Results. A comprehensive methodology for designing parts of engines and cars has been developed. The main principles of creating spatial models have been determined in order to achieve their flexibility and simple editing. Methods of automating the development of drawings and design documentation are described. The software options for the primary verification of static strength and frequency analysis are considered. A calculation program has been developed for constructing transient and amplitude-phase-frequency characteristics. The mathematical spatial modeling of typical surfaces of the camshaft is provided with the aim of further research and optimization of the development of a control program for processing on a CNC machine tool. Originality. The defined basic principles of designing parts of engines and cars provide an opportunity to create a flexible spatial model and more fully automate the process of drawing up technical documentation. The developed mathematical spatial models of the supporting and working surfaces of the camshaft make it possible to write a control program with the determination of the optimal trajectory of the mutual movement of the part and the tool. Practical value. The obtained results can be recommended when designing car parts and assemblies.

Introduction. Modern therapy defines oxidative stress as one of the key links in the pathogenesis of different diseases, which makes the search for new low molecular weight antioxidants actual [1]. The widely used methods are imperfect, since they reflects reactivity of the sample under artificial conditions [2–4]. The proposed technique of using the "Ecolum" biosensor makes it possible to preserve the advantages of in vitro methods and improve the accuracy of determination through the use of biological reactions of cells [5, 6].Aim. Studying of the antiradical and antioxidant activity of 2-aminopyrroles, using in vitro methods and quantum-chemical calculations. Materials and methods. Earlier, derivatives of 2-aminopyrroles were obtained. Antiradical activity of the compounds was studied using the DPPH test (2,2-diphenyl-1-picrylhydrazyl). Antioxidant activity was evaluated on the model of oxidative stress using the «Ecolum» biosensor. The calculation data of the indices of reactivity in the approximation of the gas phase were obtained using quantum-chemical methods.Results and discussion. The antioxidant activity test indicated a higher antioxidant potential of 2a, compared to 2b. Antiradical activity test revealed a greater antiradical potential of 2b. Quantum-chemical calculations showed that 2b is characterized by a higher ionization potential, which may indicate its greater resistance to oxidation compared to 2a.Conclusion. The study of the antiradical and antioxidant activity of 2-aminopyrroles showed the importance of developing a methodology for the search for new antioxidants, because of antiradical activity test deviations, compared to living cell reactions.

The process of synthesis of CuAu nanoclusters from a high-temperature gas phase was simulated. The molecular dynamics method was used. 91124 Cu and Au atoms were used as the initial configuration. The atoms were arranged randomly in space, the average distance between them was 30 Bohr radii. The set of parameters was chosen in such a way as to simulate the conditions of the inert gas condensation. This system was cooled with a thermal energy removal rate of 108 K/s. Based on the data obtained, conclusions were drawn about the main stages of the evolution of the model system. It is shown that the initial stage of synthesis consists of five different stages, which gradually lead to the formation of primary spherical nanoparticles of the CuAu binary alloy. At the final stage, the eventual transformation of the formed primary nanoparticles takes place. The initial atomic atmosphere almost completely disappears and spherical binary nanoparticles are formed, a characteristic feature of which is the displacement of gold atoms to the surface.

The process of synthesis of CuAu nanoclusters from a high-temperature gas phase was simulated. The molecular dynamics method was employed, 1124 Cu and Au atoms were used as the initial configuration. The computer model of synthesis from the gas phase was based on an experimental setup located at the Budker Institute of Nuclear Physics SB RAS. On the basis of the data obtained, conclusions were made concerning the real chemical composition of clusters at the final stage of formation. It is shown that clusters larger than 400–500 atoms adhere to the given target ratio. The maximum deviations from the target ratio were recorded only for atomic vapor of stoichiometric composition. In other cases, with a reduction in the percentage of gold atoms in the initial pair, the deviations of clusters from the required composition decreased. It was determined that the reason for this was a different crystal structure of the nanoparticles obtained by modeling.

The article considers the process of formation of binary Cu-Au nanoclusters with different target composition from a high-temperature gaseous medium. The molecular dynamics method was used. The main attention was paid to studying formation of the crystal structure in such clusters and determination its type. It is shown that an increase in the percentage of gold atoms in the primary gaseous medium significantly affects the formation of the internal structure of simulated nanoparticles. With a relatively small increase in the proportion of gold atoms, there is a complete disappearance of clusters with the fcc structure. The formation of nanoparticles with, as a rule, five-particle symmetry is observed. In this case, the Dh configuration prevails. If both precursors are evaporated at the same rate, then an increase in the percentage of gold atoms in the gas mixture leads to the fact that CuAu clusters are often unable to form any clearly distinguishable crystalline form, due to which approximately every fourth cluster was fixed in the amorphous state. We concluded that the cause of this phenomenon may be the separation of atoms of different types, which is typical for binary nanoparticles of the studied chemical composition.

Silver nanoclusters with diameter of 3,0 to 7,0 nm were studied by the molecular dynamics method using the tight binding potential TB-SMA (second moment approximation of tight-binding potential). A search was made for the stability limits of structural modifications of these nanoclusters for determination of the size limit of the thermally induced structural transition from the initial amorphous morphology to the fcc phase. The new data were compared with the results of previous studies for Ag nanoparticles up to 2,0 nm in size with initial fcc and amorphous structures. It is shown that the studied nanoclusters can be conditionally divided into three categories. The first one (N < 100 atoms) is characterized by partial preservation of the original morphology. For the second one (d < 4,0 nm), there is competition between the icosahedral and decahedral structures. And for the thirds (d > 4,0 nm), the mixed fcc/hcp phase predominates. In this case, the size limit of the transition from the initial amorphous morphology to the structure characteristic for the bulk matter is a diameter of about 7,0 nm.

The paper considers a method for justifying the choice of a corrosion-resistant material for the manufacture of a blowout preventer body based on computer simulation of an elastic-plastic task in the ANSYS Mechanical APDL software. To describe the material properties, a multilinear deformation model is used, the reference points of which are calculated as a result of working out the macro developed by the authors based on two models: RambergOsgood and the “method of sequential corrections” proposed by TSAGI specialists. The paper presents the results of computer simulation on the loading of the PShKM-ASMT-114x21 preventer body by working and double starting pressure for four variants of body materials. The calculations confirmed the high safety factor of the body for the currently used 40X steel showed sufficient working capacity of corrosion-resistant steels 20X13 and 30XMA. However, a computer experiment detected very extensive zones and the level of plastic strains as a result of loading the body made of 12X18H10T steel with double starting pressure. The obtained results indicate that the investigated preventer can be manufactured in corrosionresistant versions K1 and K2, but for the execution of K3 it is necessary to develop a fundamentally different geometry of the body.

Aim. The theoretical and experimental studies of the effectiveness of reducing the level of the magnetic field in two-storey cottage of the old building of a power transmission line with a horizontal arrangement of wires by means of active shielding with single compensation winding. Methodology Spatial location coordinates of the compensating winding and the current in the shielding winding were determined during the design of systems of active screening based on solution of the vector game, in whith the vector payoffs is calculated based on Biot-Savart's law. The solution of this vector game calculated based on algorithms of multi-swarm multi-agent optimization. Results The results of theoretical and experimental studies of the effectiveness of reducing the level of the magnetic field in two-storey cottage of the old building of a power transmission line with a horizontal arrangement of wires by means of active shielding with single compensation winding are presented. Originality. For the first time, the theoretical and experimental studies of the effectiveness of reducing the level of the magnetic field in two-storey cottage of the old building of a power transmission line with a horizontal arrangement of wires by means of active shielding with single compensation winding are considered. Practical value. From the point of view of the practical implementation it is shown the possibility to reduce the level of magnetic field in two-storey cottage of the old building from power transmission line with a horizontal arrangement of wires by means of active shielding with single compensation winding to the sanitary standards of Ukraine.

The article describes the system of casting computer simulation software PoligonSoft. The main features of the system and work stages are described. Particular attention is paid to the features of the latest version of the software product: what’s new in the flow and stress solvers, what’s new in the preprocessor and mesh generator. The analysis of the convergence of the simulation results and the collection of experimental data was carried out.

A composite model of powder materials has been constructed based on the Mor-Coulon and Drucker-Prager plasticity conditions. However, most studies were carried out using the Drucker-Prager plasticity condition. A simplified version of the plasticity condition for the curved part of the Drucker-Prager Cap-shaped model in the case of plastic deformation of powder materials is shown. To build a real typical Drucker-Prager model, tabular data on the values of the four main parameters of powder materials were used, obtained in cases of various volumetric plastic deformations εp vol based on experimental data. Computer simulation of the process was carried out in the MS EXCEL software environment. Based on the obtained results, plots of a typical Drucker-Prager Cap-shaped model are constructed. [ABSTRACT FROM AUTHOR]

7th International conference “NANOBIOPHYSICS: Fundamental and Applied Aspects” (NBP-2021) took place on October 4-8, 2021 at B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine (Kharkiv, Ukraine). Previous six conferences, starting from 2009, were organized due to joint efforts of B. Verkin Institute for Low Temperature Physics and Engineering of the NAS of Ukraine and Institute of Physics of the NAS of Ukraine on biennial basis in Kharkiv and Kyiv alternatively. Among 80 registered participants from 16 countries about 40 scientists have presented their lectures and posters offline and other participants were joining the sessions online. 16 keynote lectures and 18 oral presentations were made and 51 posters were discussed offline and online. The goal of the conference was achieved: urgent problems, advances and perspectives of the topical scientific direction of nanobiophysics which embraces achievements of modern molecular biophysics and nanotechnology were discussed. The subjects of physical aspects of biomolecular nanosystems, properties of biomolecules on nanoparticles and nanostructured surfaces, nanobiohybrids formation by 1-D or 2-D nanomaterials with bioobjects, theoretical calculations and computer modeling of nanobiosystems, and applied aspects of nanobiophysics were highlighted at the related sessions. Several additional accompanying events were organized in the framework of the conference, including a Round Table “How biophysics and nanosciences meet modern challenges: the case of COVID-19”, a special session of the Ukrainian Biophysical Society, and SPIE (The International Society of Optics and Photonics) and OSA (The Optical Society) Workshop “Career development opportunities for young scientist and students”. Book of abstract based on NBP-2021 materials was published.

Aim. Development of the method of multi objective synthesis of stochastic robust control by multimass electromechanical systems to satisfy various requirements for the operation of such systems in various modes under non-gausian random external disturbances. Methodology. The problem of multi objective synthesis of stochastic robust control by multimass electromechanical systems to satisfy various requirements for the operation of such systems in various modes under non-gausian random external disturbances solved based on the choosing of weight matrices in the robust control goal vector.The calculation of the target vector is performed based on the solution of the zero-sum vector antagonistic game. The components of the game payoff vector are variable quality indicators that are applied to the system operation in various modes. The calculation of the components of payoff vector game are performed based on the simulation of the initial system closed by the synthesized stochastic controllers in various operating modes and under various external influences and variations in the parameters of the uncertainty of the initial plant. Results. The results of multi objective synthesis of stochastic robust two-mass electromechanical servo systems modes under non-gausian random external disturbances in which differences requirements for the operation of such systems in various modes were satisfied are given. Based on the results of modeling and experimental studies it is established, that with the help of synthesized robust nonlinear controllers, it is possible to improve of quality indicators of two-mass electromechanical servo system in comparison with the system with standard regulators. Originality. For the first time the method of multi objective synthesis of stochastic robust control by multimass electromechanical systems to satisfy various requirements for the operation of multimass systems in various modes is developed. Practical value. From the point of view of the practical implementation the possibility of solving the problem of multi objective synthesis of stochastic robust control systems to satisfy various requirements for the operation of multimass electromechanical systems in various modes is shown.

Aim. Development of the method of multi objective synthesis of nonlinear robust control by multimass electromechanical systems to satisfy various requirements for the operation of multi-mass systems in various modes. Methodology. The problem of multi objective synthesis of nonlinear robust control of multimass electromechanical systems is formulated and the possibility of satisfying various requirements for the operation of such systems in various modes based on the concept of functionally multiple membership of the state vector and the solution of the Hamilton-Jacobi-Isaacs equation is shown. A method for choosing weight matrices with the help the vector of purpose of nonlinear robust control is formed by solving a zero-sum vector antagonistic game has been substantiated and developed. Results. The results multi objective synthesis of nonlinear robust two-mass electromechanical servo systems in which differences requirements for the operation of such systems in various modes were satisfied are given. Based on the results of modeling and experimental studies it is established, that with the help of synthesized robust nonlinear controllers, it is possible to improve of quality indicators of two-mass electromechanical servo system in comparison with the system with standard regulators. Originality. For the first time the method of multi objective synthesis of nonlinear robust control by multimass electromechanical systems to satisfy various requirements for the operation of multimass systems in various modes is developed. Practical value. From the point of view of the practical implementation the possibility of solving the problem of multi objective synthesis of nonlinear robust control systems to satisfy various requirements for the operation of multimass electromechanical systems in various modes is shown.

Objectives. One of the most important tasks in the development of goniometric systems is improving resolution in terms of angular coordinates. This can be achieved in two ways: firstly, by increasing the aperture, which is very expensive and often technically challenging to implement; secondly, with the help of digital signal processing methods. If the recorded signal sources are located close to each other and not resolved by the Rayleigh criterion, it can be impossible to determine their number, location and reflection characteristics. The aim of the present work is to develop a digital signal processing algorithm for obtaining angular superresolution.Methods. Mathematical methods for solving inverse problems are used to overcome the Rayleigh criterion, i.e., obtain angular superresolution. These problems are unstable, since there is an infinite number of approximate solutions and false targets may occur. The search for the optimal solution is carried out by minimizing the standard deviation.Results. A description of a mathematical model for a goniometric system is presented. A signal processing algorithm is developed based on existing methods according to the principle of parameterization of user functions. Results of numerical experiments for achieving superresolution by algebraic methods are given along with an estimation of solution stability. The accuracy and correspondence of the amplitude of the obtained objects to the initial parameters are measured. The degree of excess of the Rayleigh criterion by the obtained solution is estimated.Conclusions. Algebraic methods can be used to obtain stable solutions with angular superresolution. The results obtained correctly reflect the location of objects with a minor error. Errors in the distribution of the signal amplitude are small, appearing false targets have negligible amplitude.

Background and Objectives: One of the disadvantages of a liquid crystal display device for information on the twist effect is its relatively narrow viewing angle. In this regard, an urgent task is to find ways to increase the viewing angle of such a device. Materials and Methods: Based on the computer simulation method, an original and simple design of a liquid crystal twist indicator with a phase compensator, which has improved angular optical characteristics, is proposed. Results: The design has a sandwich structure and consists of an input polarizer, a classic liquid crystal twist cell, a phase compensator and an output polarizer arranged in series one after another. The phase compensator consists of two identical uniaxial anisotropic films, the optical axes of which form an angle of 90°. Computer modeling made it possible to find the optimal design of this device, which, unlike other designs, has a wider viewing angle. It has been found that for each LC material there is an optimal set of design parameters of the device (orientation angle and phase compensator thickness) and there is a linear relationship between the thickness of the LC liquid crystal layer and the thickness of the phase compensator, at which the total viewing angle is maximum. In addition, a relationship has been found between the control voltage and the total viewing angle of the device. Conclusion: The proposed original design of a liquid crystal information display device based on the twist effect with a phase compensator can serve as the basis for the production of simple and technological liquid crystal displays with a wide viewing angle.

Introduction. An assessment of the influence for the type of bonds and the magnitude of the prestress of the longitudinal working reinforcement on the stress-strain state of the reinforced concrete floor slab, developed by the authors was made.Materials and methods. The studies on a finite element model of a reinforced concrete floor slab, implemented in LIRA software package were carried out.Results. The development of stress values and transverse vertical displacements directly depended on the support conditions of the floor slab.Limitation of transverse horizontal displacements on the support by any of the selected methods made it possible to reduce stresses by 3.47 - 3.78 times, deflections by 1.5 - 1.52 times, stresses - up to 11.9 times, wребро deflections - 1.18–1.53 times.Creating an end rib or limiting movement with an additional horizontal connection had almost the same effect.The transverse horizontal displacements of the lower face of the longitudinal contour rib in the direction of the 𝑢ребро span which occurred in the floor slab, which did not have an end rib and limitation of displacements in the transverse direction, were in a parabolic relationship with the magnitudes of the vertical transverse forces.In a florr slab with limited displacements in the transverse direction or with an end rib, 𝑢ребро displacements were 3.88–4.32 times less, and at the ends they depended on the deformability of the bonds, i.e. when horizontal movement was prohibited, they were equal to zero. stresses acting on the lower edge of the flange in the transverse direction, in the region of the middle of the span in the floor slab with reinforcement prestressed to the maximum value, had positive values almost over the entire width of the flange and directly depended on the thickness of the slab in each section.Prestressing made it possible to reduce deflections by 4.02 - 4.37 times, wребро deflections by 1.09 - 5.59 times, and evenly distribute stresses along the length of the longitudinal contour rib, to make they are only tensile, close to zero along its entire length.The prestressing of the reinforcement of the maximum value made it possible to increase the horizontal rigidity of the longitudinal contour rib of the floor slab and limit its transverse 𝑢ребро movements.The transverse displacements that occurred near the support of the prestressed shell slab were 1.04 - 1.2 times less than in the shell slab with non-stressed reinforcement, on the rest of the span - slightly more, changing evenly, without sharp changes, unlike floor slabs with non-stressed reinforcement.Discussion and conclusion. It is established that the optimal design of the floor slab under the study should have restrictions on the movements of the supports and the maximum possible prestressing of the longitudinal working reinforcement.The practical significance of the study is that the specified reference conditions and prestress allow maximum deformation resistance of the structure, which in our case directly affects the bearing capacity of the slab.