A.V. Sukhov, D. Fatyukhin, S. Fomushkina, Alexander Nechai
{"title":"Exploratory study for optimization of the choice of ultrasonic equipment for the deposition of functional coatings","authors":"A.V. Sukhov, D. Fatyukhin, S. Fomushkina, Alexander Nechai","doi":"10.30987/2223-4608-2024-12-19","DOIUrl":"https://doi.org/10.30987/2223-4608-2024-12-19","url":null,"abstract":"To meet the requirements affecting the quality of functional coatings, various technologies are currently being used, one of which is the use of ultrasonics. To form functional coatings, ultrasonics are used both at the stage of surface preparation and at the stage of coating deposition. Thus, at the stage of surface preparation, ultrasonics allow making surface preclean, ensuring the necessary surface roughness due to ultrasonic rolling, as well as preactivation of the surface before nitriding due to surface plastic deformation. In case of coating deposition, ultrasonics contribute to better nitriding and painting. However, ultrasonic equipment used in various preparation and coating deposition processes differs significantly in its characteristics. Thus, the ultrasonic generators vary in alternator capacity, specific material consumption, actual frequency, as well as design features that ensure stable operation, for example, automatic frequency control. The converters differ from each other in accomplishable amplitudes, power and actual frequency. In this regard, the aim of the work is to develop recommendations on the use of ultrasonic equipment in various technical processes for the creation of functional coatings. The paper studies ultrasonic equipment used in surface preparation and functional coating application process. The main process-dependent parameters aimed at choosing the required equipment have been characterized. Recommendations are given on the use of ultrasonic equipment for various functional coatings generation, when a converter-generator couple is found and it meets the requirements for most surface preparation and coating deposition processes.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"43 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140421781","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":"Technology and results of studying the surface interaction for charged particles flow in low-temperature plasma","authors":"B. Brzhozovsky, E. Zinina, V. Martynov","doi":"10.30987/2223-4608-2024-20-31","DOIUrl":"https://doi.org/10.30987/2223-4608-2024-20-31","url":null,"abstract":"An analysis of approaches to studying the interaction of the surface with a stream of charged particles is presented in order to increase the efficiency of the process of low-temperature plasma modification of the surface layer. The results of the analysis showed that it is theoretically difficult to study the interaction, therefore, it is interesting to study it empirically using electrochemistry methods that allow us to investigate the phenomena of mixing and spreading of a liquid placed on the surface caused by molecular interaction processes. An off-the-shelf technology for studying surface interaction for charged particles flow in a low-temperature plasma has been found. The technology is based on the surface interaction for a particle flow simulator, using an aqueous 3,0 % NaCl salt solution. During the course of studying, it was found, firstly, that the results of interaction are actively influenced by chemical processes between the surface and the ions of the solution, depending on the value of the potential of the electric field applied to the surface, as well as due to its microrelief, and secondly, that the main boundary process running under surface interaction and solution is adsorption. The data of the analysis of the effects of exposure to the plasma surface are presented. They proved the reliability of study results, since the course of chemical and adsorption processes also take place. In general, the materials presented in the article allowed making conclusion that the developed technology makes it possible to determine the conditions that ensure an increase in the efficiency of the low-temperature plasma modification process contributing to the improvement of both surface (electrochemical) and volumetric (physical mechanical and electrophysical) properties if it is used either in the initial state or in the state changed by plasma particles.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140419922","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":"Forecasting and assessment of tribotechnical efficiency of the nitration case of machine parts","authors":"Lidiya Kuksenova, Maria Alekseeva","doi":"10.30987/2223-4608-2024-28-40","DOIUrl":"https://doi.org/10.30987/2223-4608-2024-28-40","url":null,"abstract":"Following the laws of tribology and tribotechnics, also the results of experimental studies of reality of structure and properties change in the zone of contact tribodeformation of structural steels and alloys of different structural classes subjected to nitriding, an approach to forecasting and comprehensive assessment of the tribotechnical efficiency of nitriding of structural materials and products made of them has been developed. Analysis of the patterns of changes in the structure of the diffusion zone of nitriding steels: abnormal, martensitic and austenic, and relative wear resistance tests, taking into account their composition and technological parameters of the treatment process, showed that maximum wear resistance was provided by a nitration coating containing hardening dispersed particles of incoherent nitrides, ensuring a lower liability to brittle behavior of the nitration case due to low level of matrix level microdeformation. At the same time, preliminary types of treatment (thermal treating and deformation processing) of nitriding steels contribute to structural and phase state of the surface layer, which has added tribological performance. For nitrided ferroalloys with different matrix lattices, the most significant characteristics of the structural state and properties of the surface layers affecting the level of surface fracture under friction have been found empirically: the particle size of nitrides of alloying elements, the distance between them, the density of their distribution, the matrix lattice microdeformation, the values of X-ray lines intrinsic broadening for structural components of the material in the friction deformation zone, the hardness of the nitration case and its changes under friction. These experimental results are taken as a principle of the proposed method for forecasting and assessment of metal tribotechnical efficiency. This principle of method is based on a tribological criterion containing micro- and macroscopic characteristics of the material in the zone of contact deformation under friction, the choice of fabricating methods for the product takes place to ensure an acceptable level of wear intensity. Then, by measurement, using surface large deformation method, the ability of the nitration case formed as a result of treatment according to the selected treatment schedule to perceive surface nondestructive plastic deformation is evaluated. It affords a basis for the selected nitriding treatment schedule. The completion of the assessment is the determination of the values of the maximum operability of the nitriding material under conditions of friction and wear (alarm pressure when a tribocouple operates steadily; critical pressure when it is inoperable, but its operation is possible with short-term overloads; the average total wear intensity of the couple combined). The totality of the identified parameters allows recommending the material, its working and predicting operating modes and durability o","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140420318","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":"Study of organic compounds effect on samples microstructure of laser powder surfacing for SmFe powders in a magnetic field","authors":"Dmitriy Yacko","doi":"10.30987/2223-4608-2024-3-11","DOIUrl":"https://doi.org/10.30987/2223-4608-2024-3-11","url":null,"abstract":"The paper presents two main directions for improving the efficiency of permanent magnets (PM), by changing chemical composition of the future magnet and through variations of magnetic field shape. Increasing the efficiency of PM by changing chemical composition over the decades has made it possible to reduce multiply the size of the final product. In turn, increasing the efficiency of PM by alternating the magnetic field shape is a relatively new direction. Based on the analysis of the presented methods for increasing the efficiency of PM, it is proposed to use additive technologies, namely laser powder surfacing for the manufacture of permanent magnets. To conduct experimental studies, the KUKA robotic complex and permanent magnets are used as a source of a permanent magnetic field. The paper presents some modes of laser powder surfacing of Sm and Fe powders. A complex of six neodymium magnets is used to maintain a magnetostatic field. Strength distribution of the magnetizing field between the magnets and in the main working area is described. The external view and condition of the powders used for the manufacture of experimental samples are presented. Experimental samples and selective approach for analyzing the microstructure and concentration spectra of elements are described. The microstructure and distribution of elements in the obtained samples were studied depending on the texture of the sample relative to the magnetic field and laser surfacing mode. The effect of the applied organic binders on the microstructure and chemical composition has been determined. The distribution of elements in the samples and the transition layer between the support plate and the deposited metal is studied.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"57 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140422671","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}
V. Tikhomirov, M. Shalygin, M. Izmerov, Alexei Krutov
{"title":"Fractal dimension of a discrete contact","authors":"V. Tikhomirov, M. Shalygin, M. Izmerov, Alexei Krutov","doi":"10.30987/2223-4608-2024-41-48","DOIUrl":"https://doi.org/10.30987/2223-4608-2024-41-48","url":null,"abstract":". Contact interaction ability rating for engineering surfaces and their fractal models is carried out. Fractal models describe roughness component geometry properly, they are adequate to the initial engineering surfaces and possess a random component when modeled, which makes it possible to generate a new surface with the desired geometric parameters at all times, allowing the study of the contact interaction of surfaces to be carried as many times as necessary. When solving contact problems of rough surfaces for simplification of calculations, the replacement of the initial contact with the interaction of a smooth surface with a surface having an equivalent roughness, necessary to be determined, is usually used. The paper outlines the principles of finding the fractal dimension of engineering surfaces, as well as an equivalent surface in contact with a smooth one, when the conjugation of both is equivalent to the contact of the initial surfaces. At the same time, it is shown in this work that for anisotropic initial surfaces there are completely different parameters of contact interaction in different directions of their combination, which must be taken into account in the analysis and modelling. The fractal dimension of the equivalent surface was done using the well-known \"perimeter-area\" method, which, when determining the contact parameters, including the fractal dimension, allows taking into account the direction of the processing traces. Thus, this paper presents a method for determining the fractal dimension of both the surface and the fractal object, and also a contact spots map, an area ratio turndown for the actual contact area to the area of the maximum spot is shown as well, a procedure for estimating the fractal dimension necessary to determine the parameters of the contact interactions of rough surfaces, is proposed.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139591446","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":"Investigation of mode elements effect and the influence of milling cutter teeth space on technological parameters and temperature field of work on a thin-walled parts workpiece","authors":"Aleksandr Unyanin, Aleksandr Chudnov","doi":"10.30987/2223-4608-2024-23-29","DOIUrl":"https://doi.org/10.30987/2223-4608-2024-23-29","url":null,"abstract":"When machining workpieces of thin-walled parts, the temperature field differs from the field, which is formed during massive workpieces treatment. The reason for this is that machining of a thin-walled billet is interfered with its surface, being opposite to the one under machining. It has a significant effect on the temperature field, since the intensity of heat removal from this surface into the environment is significantly less than heat removal into the underlying layers of a massive material blank. In this regard, the problem of finding a rational mode of the machining process of thin-walled workpieces is relevant. The aim of the study is to determine the effects of the elements of the milling mode of thin-walled workpieces and milling cutter teeth space on the technological parameters of the milling process of titanium alloy workpieces and to develop recommendations for choosing this milling mode. For this purpose, a numerical modeling of the technological parameters of the milling process of blanks of massive workpieces and thin-walled parts made of titanium alloy, was performed experiencing various combinations of feed to the milling cutter tooth, cutting speed and milling cutter teeth space. When machining a thin-walled workpiece, due to less intense heat removal from the cutting zone into the workpiece, the temperatures in the areas of chip contact with the front surface of the tooth, the back surface of the tooth with the workpiece and the temperature of the workpiece itself are higher than when in a massive workpiece treatment. The patterns of changes in the parameters of the milling process of thin-walled workpieces depending on the feed, cutting speed and the milling cutter teeth space are established. With a larger tool stepover, the average and maximum temperatures in the areas of chip contact with the front surface of the tooth and the back surface of the tooth with the workpiece are lower in most of the combinations of mode elements used. Equations that establish the effect of feed on the milling cutter tooth, cutting speed and spacing of teeth on the parameters of the machining are obtained. The results of the study will allow choosing a rational milling mode and spacing of teeth in the work on workpieces of thin-walled parts made of titanium alloy.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"11 35","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139591430","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 development of computer-aided planning principles for multiproduct machining processes","authors":"Sergey Mitin, Petr Bochkarev","doi":"10.30987/2223-4608-2024-16-22","DOIUrl":"https://doi.org/10.30987/2223-4608-2024-16-22","url":null,"abstract":"The scientific principles of improving the system of automated planning of technical processes in the conditions of multiproduct machining industries are viewed. The study of modern approaches to automation of design and implementation of machining processes taking into account the production situation, is carried out. The use of the system of automated planning of multiproduct machining processes is justified, because its basic procedure includes a possibility of real-time interaction between subsystems design and implementation of technical processes, where the key place is occupied by a database on the technological capabilities of equipment and tooling. The interrelation of the system of automated planning of multiproduct machining processes with subsystems for assessing production manufacturability, monitoring technological equipment state, control and measuring procedures and assembly, is shown. The principle of designing multiproduct machining processes, generated for a given range of parts, taking into account the condition and capabilities of the production system, is presented. It is proposed to use the value of the total manufacturing time of a given range of parts as a generalized criterion for the efficiency of the production system. Ranking technique of design procedures according to the degree of influence of the decisions made on the generalized criterion of efficiency of the production system, is described. A model, based on genetic algorithms, is characterized, allowing the system being automatically adjusted to the conditions, changing during the design process. As a result, the efficiency of technological preparation of diversified production increases due to the rational distribution of manufacturing process for machining operation of parts to existing production facilities. The development of the work is aimed at increasing the level of design automation of machining processes and obtaining feedback on the current state of the production system.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"10 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139591555","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":"Hot forming of welded blanks of aluminum alloy sheets 1565 chM","authors":"Viktor Ovchinnikov, D. Polyakov","doi":"10.30987/2223-4608-2024-7-15","DOIUrl":"https://doi.org/10.30987/2223-4608-2024-7-15","url":null,"abstract":"The details of forming in cold or heated position for welded blanks of alloy 1565chM with a thickness of 8,0 mm, performed by friction stir welding, are viewed. It is found that welded joints of alloy 1565chM with a thickness of 8,0 mm, obtained by friction stir welding have high strength properties together with sufficient toughness. Thus, bending angle of the joints is 165…170 °. The strength factor of the welded joint is 0.96 of the strength of the base metal. At the same time, the temporary resistance of the weld metal exceeds temporary resistance of both: base metal and the welded joint in its value. The 1565chM alloy joints, made by friction stir welding have good formability under cold deformation. This special feature of welded blanks made of 1565chM alloy sheets is explained by the presence of a fine-grained recrystallized structure in a stir zone, which is formed as a result of heat impact and force action of the working tool on the material to be welded. Welding modes providing specified mechanical properties of the joints were used for welding shells (blanks) of gas cylinders (liners). Manufacturing technique for such cylinders includes the following operations: welding of the shell, calibration of the shell, quality control of the weld on the shell, jumping into a hot mold for forming bottoms, welding of fittings and general tightness control. Experiments on forming liners bottoms due to the shell jumping into a heated to 450...500 °C mold have shown that there is an intensive weld metal runout due to differences in the strain capacity of the weld metal and the base metal. This behavior of the weld metal during hot forming can be explained by superductility of the weld metal owing to the presence of a recrystallized ultrafine-grained structure. It was found that starting from a temperature of 400 °C, the relative elongation of the weld metal significantly exceeds the elongation value of the base metal. In case of 450 °C, this difference reaches \u000072 %. For the weld of the 1565chM alloy, starting from the heating temperature of 540 °C, an abnormal grain growth occurs along the entire weld.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"4 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139591841","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":"Intensification of high-temperature bottom plates forming","authors":"Viktor Demin","doi":"10.30987/2223-4608-2023-9-14","DOIUrl":"https://doi.org/10.30987/2223-4608-2023-9-14","url":null,"abstract":"The issues of high-temperature forming for the production of elliptical steel beaded bottoms, used in vessels and apparatuses with an internal diameter from 300 to 1800 mm, made of carbon, alloy and ply steels, are viewed. There is information that the authors have been studying this forming process of a workblank with no temperature pattern change. There is also data on examples of tests that allow reducing the thickness difference in the bottom plate from the standard 15 % of relative deformations to 12%. It is shown that the use of a variable temperature pattern will make it possible to increase the extraction coefficient by several times and obtain vessels consisting of two body parts. It is noted that the issue of the influence of changes in the hardening curve when heated on the stability of hot-temperature forming has not been viewed in technical publications yet. The possibility of using the QForm program for the analysis of the stress-strain state for high-temperature forming has been studied. The simulation of the heating of the billet in a gas furnace is carried out. As a result of the calculation, a temperature pattern and a distortion of the shape of the workblank were obtained. Comparison with the experiment revealed good convergence of the results in terms of temperatures and qualitative coincidence of the workblank shape. It is noted that QForm simulates the locations of the places of maximum relative deformations quite well, that is coincident with the results of experimental die forming and theoretical solutions for draw-forming of parts with a spherical bottom. Based on the results of the work, recommendations are given for obtaining bottom plates according to the first class of accuracy, when the maximum relative deformations in thickness should not exceed 4,0 %.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"10 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139154121","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}
R. Nigmetzyanov, V. Prikhodko, S. Sundukov, V. Klimenko, Vladimir Kol'dyushov
{"title":"The use of ultrasound in the process of plastic parts additive manufacturing","authors":"R. Nigmetzyanov, V. Prikhodko, S. Sundukov, V. Klimenko, Vladimir Kol'dyushov","doi":"10.30987/2223-4608-2023-15-22","DOIUrl":"https://doi.org/10.30987/2223-4608-2023-15-22","url":null,"abstract":"Despite huge prospects for the layer-by-layer synthesis of products, which makes it possible to produce parts of a unique shape, the widespread use of the method face the problems of making a proper microgeometry of the product surface, which due to the peculiarities of layer-by-layer production is rather rough, and mechanical methods of machine working often do not admit the possibility of figure-shaped parts post processing. The article studies the problem of ensuring the quality of the plastic parts surface layer obtained by additive technologies. For this purpose, it is proposed to use ultrasonic processing technologies. The existing methods of using ultrasonic vibrations in the production of plastic parts are analyzed: the manufacture of wire for 3D printing with additives, which results in an increase in the mechanical properties of the product. Besides, liquid treatment of a solvent-loaded product in order to remove supporting elements. Studies have been carried out on the finishing of parts in a solvent aerosol obtained by ultrasonic spraying. This method has a number of advantages in comparison with the treatment in solvent vapors obtained during its heating, which include the possibility of regulating the size of droplets, their moving speed, aerosol concentration, caused by changing the modes of ultrasonic treatment. As a result of experimental studies, it is found that the use of this treatment method eventuates an increase in the quality of the sample surfaces to be worked, and besides, it reduces the height parameters of roughness in the direction perpendicular to the layered growth of the product by more than a factor of ten. The mechanism of changing the microgeometry of the surface is as follows: when aerosol droplets contact the surface, part of the material forming the protrusions dissolves and fills valleys, while in the liquid state; after finishing the work, the material polymerizes, generating a surface with improved features.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"88 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139154391","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}