Science intensive technologies in mechanical engineering最新文献

{"title":"Study of the technique performance for the correction of the mode of the machining process with time-varying parameters in the conditions of technological information uncertainty","authors":"Aleksandr Unyanin, P. Finageev","doi":"10.30987/2223-4608-2023-23-29","DOIUrl":"https://doi.org/10.30987/2223-4608-2023-23-29","url":null,"abstract":"A technique for correcting a machining mode with time-varying parameters has been developed. The technique allows minimizing the impact of the uncertainty of technological information caused by the incorrectness of mathematical dependencies and models used for calculating the parameters of the process or due to the lack of initial data for the selection of parameters of mathematical models. It provides for the corrective dependencies and models according to the current information with respect to the output parameters. The correction of the mode elements is performed according to the results of comparing the calculated and actual values of the output and current process parameters. The calculated functions of changing the output parameters over time are determined. The routine for determining the interrelated current and output parameters of the processing process allows calculating their values depending on the operating time of the tool. According to the results of comparing the calculated values of the process parameters with the values that should be obtained at a time equal to the efficient tool life, the correction of the mode elements is performed. If the calculated values of the output parameters do not exceed their limit values, then the operation mode should be intensified for the sake of increasing productivity. The intervals of variation by controlled factors are determined, which allow changing the output parameters at a time equal to the efficient tool life by the desired value. When calculating the intervals of variation by controlled factors at the first stages of mode adjustment, they are guided by the initial models and dependencies describing the process. The necessary result may not be achieved due to the uncertainty of the information, including the incorrectness of the models. Therefore, if necessary, the subsequent stages of mode adjustment are put into operation. Based on the actual values of the output parameters, the process models are adjusted, and the variation intervals by controlled parameters are calculated using adjusted models. The application of the developed method of mode correction makes it possible to increase the turning performance by 30…35 % while ensuring the required quality of the machined parts within a given period of tool durability.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"70 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139153214","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":"Technological control of surface operational roughness parameters for sliding friction pairs through combined antifriction surfacing","authors":"M. Nagorkin, Vladimir Fedorov, A. Suslov, A. Totay","doi":"10.30987/2223-4608-2023-37-45","DOIUrl":"https://doi.org/10.30987/2223-4608-2023-37-45","url":null,"abstract":"The article presents study results of the technological control ways for roughness operational parameters generation in tribo-elements of sliding friction pairs through combined antifriction surfacing methods. The possibilities of technological control of the roughness parameters of the parts surfaces were studied for two types of part cutting – based on both: the application of hard wear-resistant nitride-containing coatings on the surfaces of parts and on the application of soft copper-containing work plates on the working surfaces of parts in combination with surface plastic deformation technique. Surface plastic deformation was carried out by diamond burnishing or ball burnishing. As controlling factors in experimental studies, both: the conditions for surfacing of parts and the run-in conditions in sliding friction pairs were viewed. Break-in process of pairs was carried out on a programmable testing unit (friction machine), which allows simulating both: static loads and dynamic loads that change together with the specified parameters in a periodic manner. Models for quantitative ratings of the influence of surfacing factors of parts using anti-friction technologies and their further development in sliding friction pairs on operational roughness parameters generation, which, in turn, have a significant impact on the operational properties of tribo-elements. To assess the degree of technological factors effect of the treatment on the generation of operational roughness of parts, their ranking by the Pareto method was carried out. The degree of consistency of control factors impact on operational roughness parameters generation was assessed using the coefficient of rank concordance. The information presented in the article is necessary for practical application in the field of designing technological methods of combined antifriction surfacing of parts for sliding friction pairs of machines and mechanisms.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"92 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139154339","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":"Space function recovery of the distribution of coating inhomogeneities according to the distribution function on the polished specimen","authors":"Sergei Kokarev, Mikhail Soloviev, Sergey Baldaev, Lev Baldaev","doi":"10.30987/2223-4608-2023-3-16","DOIUrl":"https://doi.org/10.30987/2223-4608-2023-3-16","url":null,"abstract":"In the experimental studies of the structure of the special coating layer overlaid on metal applying gas-thermal spraying technique, one of the main methods is the study of polished specimen micrography. According to the computer analysis of microphotographs, it is possible to obtain the distribution function of inhomogeneities in the sample. However, since micrography is a flat image, the resulting function will be two-dimensional, whereas in a real sample, the distribution of defects is described by a three-dimensional function. In this paper, the problem of the space function recovery for the distribution of defects in a gas-thermal coating is viewed on the basis of the analysis of polished specimen micrography. The actual inclusion of an irregular shape is replaced by an effective three-axis ellipsoid. The problem is solved in the general form of reduction of the space function f of inhomogeneities distribution according to their distribution function f P on the cross - sectional plane P, which includes some integral transformation I. It is shown that in the special case of spherical particles, the inversion I^(-1) exists and is an integral transformation of the same type as I. The space distribution of spherical particles is also viewed, which does not depend on the longitudinal coordinate z, where particle sizes are limited at each point by a function R(x,y), depending on the coordinates. This distribution is suitable in its essense to the stationary spraying technology, when in deep layers near the substrate, the coating material melts completely and forms a single melt, while closer to the surface and edges, the parts that are not completely melted form inclusions of noticeable sizes. The reduction of the Fuller distribution law, used to optimize the granulometric composition of powder materials, is viewed as a second example. It is found that the reduction of the density of the ellipsoid distribution function to the section of a flat strip transfers the density of the distribution of centers as original, and the product of Fuller distributions times independent parameters is transformed into the product of distributions times the opposite degree parameters and also the previous values of the parameters of the ellipsoid","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136227199","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":"Additive technologies for magnetic materials generation","authors":"Dmitriy Yacko","doi":"10.30987/2223-4608-2023-17-23","DOIUrl":"https://doi.org/10.30987/2223-4608-2023-17-23","url":null,"abstract":"Materials and materials with magnetic properties are one of the mainstays of the world of mankind. Magnets are the key elements of most devices used in industry, science and technology. The development of permanent magnet manufacturing technology taking into account the maximum efficiency of the generated magnetic field with a minimum size of the magnet can be divided into two key directions: changing the composition of the magnet and changing the shape of the magnetic field. The research in this paper is aimed at developing a technology for manufacturing shaped magnets for controlling the shape of the magnetic field. Modern production technologies actively use various software products to simulate the design, composition, physical and chemical properties of the final product. For more precise manufacturing and minimization of post-processing, 3-D automated complexes are used, that make it possible to produce a finished product. Manual labor is gradually being replaced by machine labor, and the role of man at the place of production is gradually changing. Large-scale production begins to use robotic systems and conveyors, which significantly increases productivity, reduces costs and the influence of the human factor on the quality of the finished product. The market of additive technologies has been growing at an increasing pace in recent years. The paper considers the application of additive technologies for obtaining materials of complex shape with magnetic properties. The substantiation and solutions of the main obstacles in the development of a new technology for the manufacture of shaped magnetic materials are proposed. Technological solutions and equipment giving the possibility to obtain magnetic materials through the use of additive technologies make a motion.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"32 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136227200","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":"Isothermal upset of titanium rod blanks using a punch with a ruled surface","authors":"Sergey Larin, Yulia Bessmertnaya","doi":"10.30987/2223-4608-2023-3-9","DOIUrl":"https://doi.org/10.30987/2223-4608-2023-3-9","url":null,"abstract":"The operation of obtaining cylindrical products with a titling pad made of titanium alloy VT6 is viewed in the article. The operation involves impacting a bar blank made of titanium alloy VT6 with the use of a punch having sloped edge. When obtaining parts having titling pad made of difficult-to-form alloys, it is necessary to formulate the modes of technology. It is required to specify the rates of deformation and the impact of contact friction on the kinematics of the material flow and the force of shape change to assess the capabilities of the process performed by CAE modeling. Therefore, the simulation of obtaining cylindrical products with a titling pad made of titanium alloy VT6 was performed in the DEFORM modeling program. The influence of the speed conditions of the operation on the change in the values of stress intensities in the product was found. The dependences of the influence of the angles and rates of deformation on the landing force are revealed. The results of theoretical studies obtained during the simulation were summarized. A regression analysis of the results obtained during the simulation was performed. Based on the simulation results, expressions for estimating the intensity of stresses are obtained. The results of regression modeling are in good agreement with the results of computer modeling. Using quantitative modeling results, a regression assessment of the force was taken. Regression equations in natural values are obtained for the assessment of the impact of key process parameters during setup, which can be useful directly when assigning technological modes of titanium alloy blanks setup. The results can be used in the implementation of manufacturing technologies for parts with flange seals, characterized by the best strength characteristics and good load resistance.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136018292","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":"Modeling of the selective laser melting process in additive manufacturing","authors":"Aleksandr Grigoryants","doi":"10.30987/2223-4608-2023-20-29","DOIUrl":"https://doi.org/10.30987/2223-4608-2023-20-29","url":null,"abstract":"The possibilities of theoretical analysis based on numerical modeling of complex processes of additive manufacturing by selective laser melting method are viewed. Methods of high-precision modeling of the formation of a single melt bath are discussed, taking into account the geometry of the formed powder layer, the energy distribution in the spot, the effects of ray re-reflection, the vapor recoil force, the Marangoni effect and denudation mechanisms. Experimental studies on the cultivation of samples from BrX copper powder with particles of 20...50 microns in size by selective laser melting using continuous fiber laser radiation with a wavelength of 1.064 microns were carried out. In particular, all the experiments were carried out under conditions when growing conditions and modes are completely coincident with the calculated model. To assess the accuracy of the modeling system, the dimensions of the melting region and the morphology of the surface of the melt were compared. The presented computational model was used in the development of technology for growing products from copper alloy powders using selective laser melting method. Research in the field of modeling the stress-strain state in a composite material formed in the SLP process, consisting of an Ak9ch alloy matrix reinforced with titanium carbide particles, is also presented. Calculations were performed to identify the influence of shape (sphere, icosahedron, prism), size (1,0 microns; 5,0 microns; 10 microns) and mass concentration 
 (1,0 %; 3,0 %; 5,0 %; 7,0 %; 10 %; 15 %), taking into account the presence of pores of various shapes. The results of calculations are compared with the results of experiments. Numerical models with subsequent experimental approbation of the optimal variant make it possible to significantly reduce the time spent for the development of new complex and promising additive technologies.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"146 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136018293","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":"High-tech technologies in assembly production","authors":"Uyliy Tchigirinsky, Aleksandr Ingemansson","doi":"10.30987/2223-4608-2023-39-48","DOIUrl":"https://doi.org/10.30987/2223-4608-2023-39-48","url":null,"abstract":"Assembly is an important stage of production that has a substantial impact on the quality of manufactured products. Due to the complexity of structures, severization ofquality requirements and increased technical and economic characteristics of manufactured products, taking into account constant scientific and technological progress in machine building, the task of quality assuarance and achieving the maximum identity of products is becoming more and more relevant. The success of assembly automation projects implementation is associated with the need for geometric and technological design concurrency. The success of the implementation of assembly automation projects is associated with the need for both geometric and technological design concurrency. The article describes an approach to solving this problem considering the consistent technological improvement of the product through assembly prism. Currently, the problem of assembly quality is a key one in mechanical engineering field. The article discusses the intercoordination of the assembly with all the stages of production, going before. An analysis of the problems associated with assembly production in this area was carried out. The level of assembly automation in Russia in the field of mechanical engineering does not exceed 10%. An increase in the level of assembly automation can be achieved only through the creation and research of new methods of automatic and robotic assembly. The article describes the technological capabilities and applications of new methods of automatic assembly. The possibilities of samples of experimental assembly equipment, created and studied at the universities of Russia, are studied. A particular problem is the lack of a single source manufacturer of automatic assembly equipment in Russia. The article draws attention to the need of the creation and implementation of intelligent assembly equipment and technologies. As a result of this analysis, issues have been identified, the solution of them can be made at the sector-specific and state levels.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"765 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136017767","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":"Calculation of high-duty cold reduction rollers grinding cycles based on radial force cycle optimization","authors":"S. Bratan, Vasiliy Golovin, Yuriy Novosyolov, Irina Dymchenko","doi":"10.30987/2223-4608-2023-30-38","DOIUrl":"https://doi.org/10.30987/2223-4608-2023-30-38","url":null,"abstract":"Currently, the grinding operation of fabrication mill rollers through the use of fine-grained wheels is the most progressive method of finishing, because it saves from labor-intensive finishing processes in the technological cycle allowing to get a desired accuracy of the size, shape, surface roughness, physical and mechanical properties of the work material along with the reduction of manufacturing content. Considering that grinding rate of fine-grained wheels increases with an depth-of-cut increase in a single grain, the method of calculating grinding cycles by radial force for finishing of cold reduction rollers using fine-grained abrasive wheels is viewed. The calculation was carried out, and the optimal modes of a high-performance grinding cycle of parts made of steel 9X2, 55...60 HRC, wheels 1-400x50x203 63C M14 CM 8B with a change in the radial component of the cutting force at the cycle stages were determined. For experimental verification of the calculated cycle, grinding samples 
 d×l = 65×250 mm at a constant radial force corresponding to a given surface roughness and with a change in radial force were tested. Radial grinding force was set by technological system tightness and maintained by a device for registering a radial force within each run. During the experiments, the following measurements: removal of metal to diameter with a lever bracket; surface roughness parameters on a profilometer-profilograph mod. 201 were carried out. The conducted tests proved the effectiveness of design cycles with a change in radial force. When using the proposed cycles, a given surface roughness is provided, while the productivity of the operation increases by 2,0 – 2,5 times.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136018140","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":"Specificities of welds formation with aluminum alloy AK 9 obtained by selective laser melting","authors":"Viktor Ovchinnikov, Ruslan Reztsov","doi":"10.30987/2223-4608-2023-10-19","DOIUrl":"https://doi.org/10.30987/2223-4608-2023-10-19","url":null,"abstract":"The problem of obtaining high-quality plate welds made of AL9 alloy and powder by selective laser melting is viewed. Welded butt joints of plates of AK9CH alloy with a thickness of 3.0 mm were made by melting welding (automatic argon arc and electron beam welding) and friction stir welding. After welding the base metal of the AK9 alloy plates and their welded joints were subjected to X-ray transmission, computed tomography, metallographic analysis and mechanical tests for static tension and static three-point bending. X-ray inspection of welded joints made by automatic argon arc and electron beam welding revealed multiple porosity inside welds. The nuclei of pores in the weld metal are spherical micropores, formed in the parent metal during selective laser melting. The diameter of these micropores is 150...200 microns. In the welding bath during fusion welding, micropores develop up to 420...1070 microns in diameter in case of argon arc welding and 215...420 microns in case of electron beam welding. Metallographic analysis of cross-sections of welded joints performed by fusion welding revealed a characteristic pore distribution in the weld metal. So in case of argon arc welding, the largest pores were located near the front surface of the weld. In the fusion zone at the border of the weld and the base metal, pores with a diameter of 80.220 microns were located in the form of chains along the entire thickness of the plates being welded. When testing welded joints for static tension, the destruction of joints occurred precisely in this zone. The strength coefficient of the AK9 alloy joints obtained by fusion welding is as follows: for automatic argon arc welding 0.46, for electron beam welding - 0.66. It is established that the problem of porosity of welded joints is eliminated when using solid -phase welding for jointing (friction stir welding). The strength coefficient of the jointing of the AK9CH alloy plates made by friction stir welding is at the level of 0.81.0.86 of the time resistance of the base metal. The destruction of welded joints occurs along the mixing zone. In the weld zone during friction stir welding, as a result of dynamic recrystallization, a fine-grained equiaxed structure with an average grain size of 4.5...6.2 microns was formed with virtually no pores. The parent metal is represented by a cellular structure in which there are pores up to 168 microns in size.","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136018294","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":"High-techs in materials science: through-the-thickness austenitic nitriding of heat-resistant steel","authors":"Larisa Petrova","doi":"10.30987/2223-4608-2023-3-15","DOIUrl":"https://doi.org/10.30987/2223-4608-2023-3-15","url":null,"abstract":"The topicality of the research is occasioned by exaggeration of working conditions of products used at high temperatures and made of heat-resistant sheet alloys, including in particular austenitic chromium-nickel steels. When steel parts under load are operated in an oxidizing atmosphere and aggressive environments, besides resistance to electrochemical and gas corrosion, they require increased strength, hardness, and heat resistance. The increase in the characteristics of these proper-ties is achieved by three-dimensional and surface hardening techniques, which include the nitration process. The applica-tion of traditional technologies of furnace gas nitriding for chromium-nickel steels is complicated due to the problems of the low rate of the nitrogen saturation, which significantly increases the process time, and the formation of chromium nitrides, which negatively affects corrosion and heat resistance. The development of new technologies for nitrogen hardening of high-alloyed chromium-containing steels is carried out in the direction of saturation process intensification and regulation of the phase composition of the nitrided layer to minimize the formation of chromium nitrides. The article is aimed at defin-ing rational technological options and modes of gas austenitic nitriding of austenic steel, making it possible to increase strength characteristics at RT and higher temperatures without sacrificing its heat resistance. Thermodynamic modeling of the phase composition based on the CALPHAD technique shows that primary ways for minimizing the release of chromium nitrides on the nitrided surface are to increase the concentration of titanium in steel and to reduce the activity of the saturat-ing gas atmosphere, which is achieved by inert gas dilution of nitrogen. Experimental studies were carried out on sheet samples of 1.5 mm thick austenic steel of the type X18N10T with a standard (0.5%Ti) and increased (1%Ti) titane content. The experiments were carried out on a laboratory installation for high-temperature nitriding (900.1200 °); pure nitrogen and mixtures of nitrogen with argon were used as saturating media. Two-stage processes consisting of nitrogen hardening in nitrogen followed by argon afterburning were also investigated. Metallographic analysis showed that at the same nitrid-ing temperature, the amount of chromium nitrides decreases in experimental steel with an increased titanium content, and dilution of nitrogen with argon reduces the temperature of chromium nitride release. According to the study of saturation process kinetic, the time of through-the-thickness nitriding of a sheet sample under different saturation modes was deter-mined, as well as the duration of de-nitriding annealing, calculated on the basis of the known thickness of the chromium nitride zone. It was found that the dispersion hardening of the zones of internal nitriding with titanium nitrides leads to an increase in the strength characteristics of steels both at R","PeriodicalId":21570,"journal":{"name":"Science intensive technologies in mechanical engineering","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135131459","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}