Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta最新文献

{"title":"OBTAINING GRAPHENE STRUCTURES AND NANOPOLYMERS USING ULTRASONIC VIBRATIONS","authors":"V. Rubanik, V. O. Savitsky, V. Rubanik, V. F. Lutsko, I. Nikiforova, H. T. Bui, Dinh Phuong Doan","doi":"10.18323/2073-5073-2021-3-74-83","DOIUrl":"https://doi.org/10.18323/2073-5073-2021-3-74-83","url":null,"abstract":"Graphene-based polymer nanocomposites are considered a promising class of future materials. The degree of filling, the filler and binder nature, and the shape, size, and mutual arrangement of filler particles determine the properties of a polymer composite material. The destruction of nanoparticles aggregates occurs most effectively in liquid media under the action of ultrasonic vibrations. The authors proposed the technique and designed laboratory equipment for ultrasonic treatment of the finely-dispersed graphite suspension, carried out the ultrasonic treatment (UST) of finely-dispersed graphite powder. The suspensions based on graphite with a solvent were obtained. The authors carried out the experiments on producing graphene using the graphite liquid-phase exfoliation method at the ultrasonic treatment with different ultrasonic treatment times, analyzed experimental data, and selected the UST optimal time. The paper contains the results of the study of the effect of the graphite suspension base on the degree of ultrasonic liquid-phase exfoliation of graphite. The most effective synthesis of graphene structures using UST is synthesis from graphite suspensions based on dichloroethane, benzol, and dichlorobenzene. Graphene structures’ output ratio amounts to up to 66 %. The authors developed the technology for producing polymers modified with graphene structures using ultrasonic dispersion. Based on graphene synthesized by the graphite liquid-phase exfoliation, the authors obtained nanopolymers using ultrasonic vibrations, carried out DSC measurements, and studied their strength properties. The limit strength of elastic polymers is from 1.9 to 3.6 MPa at different concentrations of graphene inclusions. The residual elongation of samples within the deviation did not change and amounted to 200 %.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"60 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90688201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IDENTIFICATION OF ACOUSTIC EMISSION SOURCES IN A POLIMER COMPOSITE MATERIAL UNDER THE CYCLE TENSION LOADING","authors":"A. Bryansky, O. Bashkov","doi":"10.18323/2073-5073-2021-3-19-27","DOIUrl":"https://doi.org/10.18323/2073-5073-2021-3-19-27","url":null,"abstract":"The structure of polymer composite materials (PCM) provides high mechanical properties but, at the same time, is highly sensitive to the formation of internal defects. Therefore, when designing, manufacturing products, and assessing their reliability in service, much attention is paid to the methods of non-destructive testing, among which the method of acoustic emission (AE) has proven itself to study structural changes in material under external influence. The paper deals with the identification of typical damages in fiberglass samples made of T11-GVS9 glass fiber cloth and DION 9300 FR binder and tested under cyclic tension using the AE method. In the work, the authors solved the problem of selecting the AE informative parameters and used a clustering method to identify the nature and the formation kinetics of the AE sources. The authors performed clustering using the Kohonen self-organization map (SOM) with the Fourier spectra calculated for the AE signals recorded during cyclic tests. Based on the peak frequencies analysis of the produced clusters, the researchers determined their nature and calculated the periods of critical accumulation. When characterizing the AE sources, the authors used the peak frequencies analysis of the wavelet spectra performed for different levels of decomposition. The authors determined the damage accumulation stages of samples during testing based on own research and research by other authors’ results. The study established that registration of AE signals identified as adhesion failure can be used to identify the onset of the material destruction and characterized the local formation of micro-damages in the matrix and fracture of fibers can be used to predict the destruction of PCM.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87391329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The research of the processes of formation of porous non-ferrous metals","authors":"A. Kovtunov, D. A. Semistenov, Y. Khokhlov, S. V. Myamin","doi":"10.18323/2073-5073-2021-2-9-17","DOIUrl":"https://doi.org/10.18323/2073-5073-2021-2-9-17","url":null,"abstract":"Foamed metals are promising materials with a unique combination of mechanical and operational properties: low specific gravity, low thermal conductivity, ability to absorb acoustic and electromagnetic vibrations, and the ability to deform under a constant load. Currently, the most used methods for producing foamed aluminum and foamed magnesium are methods based on mixing gas or porophore into molten aluminum and forming a porous structure during the solidification of the aluminum melt. An alternative to this technology is the formation of a porous structure through the use of soluble granules that pre-fill the mold and after impregnating the granules with molten metal and solidifying the castings, they are leached. The work aims to determine the influence of casting modes and the size of granules on the depth of impregnation of granular filling with metal melt during the formation of porous aluminum castings. The authors proposed the technique for calculating the depth of impregnation of granular filling when producing castings of porous non-ferrous metals based on the calculation of melt cooling when moving along the thin-walled channel. The calculations made it possible to determine the depth of impregnation and establish the allowable wall thickness of the casting of porous aluminum, depending on the size of the granules used, the speed of the melt in a form, the mold temperature, and the temperature of molten aluminum. The study identified that to increase the depth of impregnation and obtain porous aluminum castings with thinner walls, it is advisable to increase the diameter of the salt granules and not the temperature and hydrodynamic modes of casting. The authors carried out calculations and identified the influence of the casting regimes and the diameter of the granules on the depth of mold impregnation to obtain porous castings from promising magnesium alloys.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73131626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The comparative analysis of thermal effects in elastomers modified with MCNT at constant DC voltage","authors":"A. Shchegolkov","doi":"10.18323/2073-5073-2021-1-63-73","DOIUrl":"https://doi.org/10.18323/2073-5073-2021-1-63-73","url":null,"abstract":"The author carried out the comparative analysis of elastomers – polyurethane (NPC) and silicone compound (NCOC) modified with carbon nanotubes (MCNT) with a mass content of 1 to 9 %. MCNTs were synthetically produced by the CVD technology using Co-Mo/Al2O3-MgO (MCNT1) and Fe-Co/2,1Al2O3 (MCNT2) catalysts. The analysis of experimental study results showed that the lowest specific bulk electrical conductivity (5×10-10 Cm×cm-1) was typical for polyurethane elastomer (1 mass. % MCNT synthetically produced using Fe-Co/2,1Al2O3 catalyst). For the silicone elastomer modified with 9 mass. % MCNT1, the specific bulk electrical conductivity was 4×10-1 Cm×cm-1. The author identified the parameters of percolation of electrical conductivity model for NPC, NCOC with MCNT1 and MCNT2, taking into account the MCNT packing factor and electrical conductivity critical index. The maximum temperature field uniformity is typical for silicone elastomer with 7 mass. % MCNT2. Nonuniform temperature field in modified polyurethane-based elastomers can be caused by the local MCNT entanglement manifested in the creation of agglomerates or more dense electrically-conductive circuit packing, which, in its turn, results in the decrease in heat power. The heating temperature of nanomodified composites produced from NCOC 1 and NCOC 2 can vary from 32.9 to 102 °С. The author studied the modes of nanomodified elastomers heat generation in the range of 6 to 30 V, compared heat generation in the elastomer-based and ceramics-based samples. The study allowed identifying the best combination of the polymeric matrix and MCNT type. For the electric heater, it is the most efficient to apply silicone compound at the 7 % MCNT concentration and, depending on the feeding voltage level of 12 or 24 V, to use MCNT1 or MCNT2.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80402576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"THE INFLUENCE OF ELEMENTAL POWDER RAW MATERIAL ON THE FORMATION OF THE POROUS FRAME OF TI3ALC2 MAX-PHASE WHEN OBTAINING BY THE SHS METHOD","authors":"D. Davydov, E. Umerov, E. I. Latukhin, A. Amosov","doi":"10.18323/2073-5073-2021-3-37-47","DOIUrl":"https://doi.org/10.18323/2073-5073-2021-3-37-47","url":null,"abstract":"The ternary carbide compound Ti3AlC2 belongs to the so-called MAX-phases – a new type of ceramic materials with unique properties. A simple energy-saving method of self-propagating high-temperature synthesis (SHS) based on combustion is one of the promising methods for the production of this MAX-phase. The application of the SHS technology is to produce a Ti3AlC2 MAX-phase porous frame with the homogeneous porous structure without such defects as large pores, laminations, and cracks is of great interest. The paper investigates the possibility of producing such a porous frame with the maximum content of the Ti3AlC2 MAX-phase using powders of Ti, Al, and C elements of various grades different in particle sizes and carbon forms (soot or graphite) as initial components. Porous frame samples were produced by the open-air burning of pressed briquettes of charge of the initial powders of the selected grades without applying external pressure. The authors studied the macro- and microstructure of the obtained samples, their density, and phase composition. The study shows that using the finest titanium and carbon powders leads to the excessively active combustion with gas evolution and the synthesis of the defective porous samples with the charge briquette shape distortion, large pores, laminations, and cracks. Besides the titanium carbide by-phase, the highest values for the MAX-phase amount in the SHS-product were obtained using the titanium powder of the largest-size fraction together with the graphite powder, rather than soot. The excess aluminum powder addition to the stoichiometric ratio to the initial charge leads to an increase in the MAX-phase amount in the SHS product, compensating for the loss of aluminum due to evaporation. An increase in the sample volume (scale factor) also leads to an increase in the MAX-phase amount in the SHS product due to the slower cooling of the product after the reaction.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89851960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In-situ study of the corrosion process of biodegradable magnesium alloys","authors":"P. Myagkikh, E. Merson, V. Poluyanov, D. Merson","doi":"10.18323/2073-5073-2021-2-18-25","DOIUrl":"https://doi.org/10.18323/2073-5073-2021-2-18-25","url":null,"abstract":"The interest in magnesium and its alloys considerably increases in recent years. These materials have a unique complex of properties: light-weight and strength make magnesium alloys promising structural materials for the aircraft industry and space application, and ability to reabsorb in vivo conditions and good biocompatibility allow producing biodegradable surgical implants of magnesium alloys, which can resorb in a human body without detriment to health. The materials for such demanding applications require detailed investigation of their properties, such as corrosion, including the kinetics of corrosion rate and staging of corrosion damage on the surface. To obtain a full view of the corrosion process, in addition to common ex-situ methods such as the corrosion rate evaluating using the weight loss method and the morphology corrosion damage investigation by optical or confocal laser scanning microscopy (CLSM), it is important to use modern in-situ methods. In-situ methods allow obtaining data immediately during the experiment and not after its completion. The authors carried out a comprehensive study of the corrosion process of the commercial ZK60 and AZ31 magnesium alloys in the simulated human-body environment (temperature, corrosion media composition, circulation of corrosion media) using in-situ methods, including hydrogen evolution corrosion rate evaluating and video-observation of a sample surface. The results show that AZ31 alloy is more corrosion-resistant than ZK60 alloy. Moreover, AZ31 alloy is prone to filiform surface corrosion, and ZK60 alloy exhibits severe pitting corrosion. Based on the comparison of the data obtained by in-situ and ex-situ methods, the authors concluded on their main differences and features.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89296435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DETERMINATION OF SUSTAINABLE LEVELS OF DESIGN ALTERNATIVES SELECTION IN THE WORKFLOW CAP SYSTEM","authors":"S. Mitin, P. Bochkarev, V. Shalunov, I. A. Razmanov","doi":"10.18323/2073-5073-2021-3-48-56","DOIUrl":"https://doi.org/10.18323/2073-5073-2021-3-48-56","url":null,"abstract":"The development of the mechanical treatment workflow CAP system is aimed at the solution of a crucial task of reduction of terms and the improvement of quality of multiproduct machining manufactures work preparation, as the existing workflow CAP systems have not got the possibility of fast response to changes in a production situation often arising within the multiproduct manufacture. The authors of this paper developed the workflow CAP system, which contains the requirements of the design activity full automation, design solution multivariance, and the feedback with the engineering process implementation subsystem. The paper deals with the development of a mathematical model and the technique of searching for sustainable levels of selecting design alternatives depending on the production situation for the whole design procedures of the workflow CAP system. The authors prove the application of a mathematical tool of genetic algorithms; describe the mathematical model using its terms. As a gene, the level of selection in a separate project procedure is specified. A chromosome is a set of genes according to the project procedures. The objective function determines the minimum total time of processing of the specified nomenclature of parts based on the ranges of gene aggregates resulting from crossing and mutation operations. The result of the work is the mathematical model and the technique for identifying the sustainable levels of selection in each project procedure ensuring the possibility of self-adjustment of the workflow CAP system depending on the production situation.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79060322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microstructure and strength of joints of nickel sheets produced by ultrasonic welding","authors":"E. R. Shayakhmetova, M. Murzinova, A. Nazarov","doi":"10.18323/2073-5073-2021-2-75-81","DOIUrl":"https://doi.org/10.18323/2073-5073-2021-2-75-81","url":null,"abstract":"Ultrasonic welding (USW) is one of the methods for producing solid-phase joints of thin metal sheets, which in the future can be used to obtain laminated composite materials, for additive manufacturing and renovation of metallic articles. The quality of joints depends on both the processing conditions and the properties of welded metals and alloys. At present, the USW conditions, the properties, and structure of weld joints of strong metals, in particular, of nickel, are underexplored. In this work, the authors studied the influence of the compressive load magnitude on the lap shear strength and the structure of joints of annealed nickel sheets with a thickness of 0.5 mm produced by spot USW. The authors carried out USW at a vibration frequency of 20 kHz with an amplitude of 15 μm, the time of welding was equal to 2 s. The compressive load magnitude was varied from 3.5 to 7 kN. The study showed that with an increase in the compressive load in the considered range of values, the strength of weld joints increased, reached a maximum, and then decreased. The joints obtained at the compressive load of 6 kN demonstrated the highest lap shear strength of 1950 N. A zone of thermomechanical influence with a gradient microstructure is observed near the contact of the welded surfaces. In a layer with a thickness of 10–20 mm, the initial coarse-grained structure of nickel is transformed into an ultra-fine-grained one with a grain size of less than 1 mm. The ultra-fine-grained layer neighbors on crystallites, the size of which is several micrometers and increases with a distance from the contact surface of welded sheets. The authors compared the results of mechanical lap shear tests and structural studies with the data obtained after ultrasonic welding of nickel, aluminum, and copper alloys.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"2014 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86807566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"EFFECT OF γ′-PHASE PARTICLES ON THE MECHANICAL BEHAVIOR AND DEFORMATION MECHANISM OF (CoCrFeNi)94Ti2Al4 HIGH ENTROPY ALLOY SINGLE CRYSTALS","authors":"A. Saraeva","doi":"10.18323/2073-5073-2021-3-84-90","DOIUrl":"https://doi.org/10.18323/2073-5073-2021-3-84-90","url":null,"abstract":"Recently, the interest of researchers has focused on a new FCC class (FCC – face-centered cubic lattice) high-entropy alloys (HEA), due to their unique properties – high values of the strain hardening coefficient, good plasticity, and ductile fracture at low test temperatures. Such a combination of properties in an FCC of HEA is achieved by mixing five or more elements in equal atomic proportions. Due to the strong temperature dependence of stresses at the σ0.1(T) yield point, these alloys have low σ0.1 values at temperatures above room temperature, which hinders their practical application. A precipitation hardening is an effective way to achieve high strength and is successfully used for hardening HEA FCC. The paper studied the influence of ageing at 923 K for 4 hours and at 1073 K for 18 and 30 hours on the mechanical behavior of single crystals of (CoCrFeNi)94Ti2Al4 (at.%) HEA FCC oriented along the [001] direction under tension. Ageing at 923 K for 4 hours and at 1073 K for 18 and 30 hours leads to the precipitation of γ′-phase particles, the size and volume fraction of which depend on the ageing temperature and time. The γ′-phase particles precipitation leads to an increase in stresses at the yield point from 47 MPa (ageing at 923 K, 4 hours) to 226 MPa (ageing at 1073 K, 30 hours) relative to quenched crystals at 296 K. The study identified the dependence of the strain hardening coefficient, plasticity, and the maximum stress level before fracture on heat treatment. The author discussed the reasons for the growth of stresses at the yield point and the strain hardening coefficient upon precipitation of γ′-phase particles.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"27 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91441870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The influence of rolling and high-pressure torsion in the Bridgman chamber on the quantitative characteristics of shear bands in an amorphous Zr-based alloy","authors":"I. Khriplivets","doi":"10.18323/2073-5073-2021-2-67-74","DOIUrl":"https://doi.org/10.18323/2073-5073-2021-2-67-74","url":null,"abstract":"Amorphous alloys based on metal components demonstrate a unique ability to realize plastic deformation under the influence of external mechanical stresses. Influenced by substantial degrees of plastic deformation in alloys, one can observe shear bands (SB) in the form of rough lines on the polished surface of the sample. The concept of shear band formation in amorphous metallic glasses varies greatly from plastic deformation processes in crystalline metals and alloys. Unlike crystalline metals, amorphous metallic glasses can exist in a spectrum of structural states with accompanying mechanical, thermodynamic, and physical properties of materials. The formation and evolution of shear bands control the fluidity and plasticity of almost all metallic glasses at room temperature, and in many cases, the formation of dominant shear bands rapidly leads to failure. The literature does not contain any rigorous quantitative description of SB main parameters, which could adequately describe in the analytical form the process of plastic deformation of amorphous alloys, similar to the dislocation and disclination theories of plastic deformation of crystals. An open question remains how the transition from macroscopic deformation to severe plastic deformations of amorphous alloys affects the key SB characteristics. In this work, using the method of optical profilometry, the author studied in detail the quantitative characteristics of the steps formed by shear bands on the surface of deformed samples of the massive amorphous alloy Zr60Ti2Nb2Cu18.5Ni7.5Al10 after high-pressure torsion (HPT) and after rolling. The study identified that the design of shear bands depends on the deformation method and showed that the magnitude of deformation had the controlling effect on the shear bands thickness (the height of the steps). The transition from deformation by rolling (e=0.4) to plastic deformation during HPT (e=2.6) leads to the threefold increase in the power of shear bands and the average distance between them.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83233612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}