Science & Technique最新文献

{"title":"Theoretical and Methodological Substantiation of the Assessment and Development of Logistics Infrastructure","authors":"R. Ivut, P. Popov, P. I. Lapkovskaya, S. V. Prokopov","doi":"10.21122/2227-1031-2023-23-1-69-78","DOIUrl":"https://doi.org/10.21122/2227-1031-2023-23-1-69-78","url":null,"abstract":"The paper presents the research results in the field of theoretical and methodological substantiation of the assessment and development of a logistics infrastructure that can operate at various levels, including regional and national. The analysis carried out has made it possible to divide all assessment methods into two groups: those based on expert assessments and those based on quantitative data. As expert methods for assessing the logistics infrastructure, such international approaches were studied as  LPI index (Logistics Performance Index); global competitiveness index; TTCI index (Travel & Tourism Competitiveness Index), where “Infrastructure” subindex includes indicators related to both the main component of the logistics infrastructure (related to the activities of air and rail transport, as well as the quality of air and ground infrastructure), and to the supporting one (number of hotel rooms, car rental companies, ATMs), as well as the annual rating of World competitiveness of the countries of the world (IMD World Competitiveness Ranking); index of involvement of countries in international trade (ETI); methodology for assessing the quality of transport infrastructure, developed by the Ministry of Transport of the Russian Federation within the framework of the program “Development of the transport system”. Studies have shown that there are few works using quantitative methods for assessing the logistics infrastructure, for example: a method for a comprehensive assessment of the transport infrastructure of a region by A. M. Kudryavtsev and L. N. Rudneva, Yu. V. Kataev’s method for a multi-level assessment of the development of transport infrastructure, methodology for assessing the attractiveness of the region’s logistics infrastructure for accommodating key objects of the warehouse and transport network developed by A. N. Rakhmangulov and O. A. Kopylova, researches of F. Carlucci. While preparing plans for the development of logistics infrastructure, it is proposed to use existing approaches, combining expert and quantitative assessment methods.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129583073","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":"Acoustic Method for Recording Initial Deformation Rate at High-Speed Forging of Rod Products","authors":"K. Y. Bykov, I. V. Kachanov, S. A. Lenkevich, V. V. Vlasov","doi":"10.21122/2227-1031-2023-23-1-20-26","DOIUrl":"https://doi.org/10.21122/2227-1031-2023-23-1-20-26","url":null,"abstract":"An acoustic methodology  has been developed and expression have been obtained for determining the initial deformation rate v0 during high-speed forging of rod products. The most rational layout of the recording device relative tothe installation elements has been established while using the obtained expressions. The essence of the developed technique lies in recording, using a recording device, sound waves generated during the departure of the impactor from the shaft of the installation and its further collision with the shaping punch, followed by finding the time ∆t during which the impactor travels the distance L between two known points of its trajectory. In turn, the value ∆t is defined as the difference between the recording time of the sound wave generated by the departure of the impactor from the shaft of the installation, and the recording time of the sound wave generated by the collision of the impactor with the shaping punch. The initial deformation rate, registered using the developed technique during the implementation of the process of high-speed forging of rod products, was v0 = 115.46 m/s.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125607092","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":"Structure and Properties of Black Ceramic MAO Coatings on Aluminum Alloys","authors":"Y. Aliakseyeu, A. Korolyov, V. Niss, A. S. Budnitskiy","doi":"10.21122/2227-1031-2023-23-1-27-33","DOIUrl":"https://doi.org/10.21122/2227-1031-2023-23-1-27-33","url":null,"abstract":"The existing processes for obtaining black wear-resistant coatings include chemical methods, anodic oxidation followed by painting in aniline dyes, electrochemical deposition, vacuum plasma treatment, microarc oxidation (MAO). Of great interest for the formation of light-absorbing coatings is the MAO method, which is characterized as a reliable and environmentally friendly process, which provides the formation of a hard ceramic-like oxide layer with high corrosion resistance аnd good adhesion to the substrate. Therefore, the development of methods for obtaining high-quality black MAO coatings with both high optical and mechanical characteristics is currently an urgent task. The paper presents the results of a study of the structure and properties of black ceramic coatings on aluminum alloy AMg2 obtained by microarc oxidation using silicate-alkaline and silicate-phosphate electrolytes containing potassium ferrocyanide and sodium tungstate as coloring components. Sodium tungsten acid and potassium ferrocyanide with a concentration of  0.5 to 2.0 g/l were added to the electrolytes as additional components that ensured the coloring of the coatings. It has been established that the most saturated black coatings in a silicate-alkaline electrolyte are formed with the addition of 1.5–2.0 g/l of sodium tungstate, and in a silicate-phosphate electrolyte with the addition of 1.5 g/l of potassium ferrocyanide. The use of an electrolyte containing sodium tungstate makes it possible to form coatings with a lower microroughness height (Ra 0.97–1.11 µm) compared to coatings obtained in an electrolyte containing potassium ferrocyanide (Ra up to 4.20 µm). The maximum wear resistance of the resulting coatings (wear rate (0.38–0.59) × 10–4 mm3/(m×N)) is achieved by treatment in the studied electrolytes with a duration of 10 min. In this case, the thickness of the coatings is 21–31 µm. A further increase in the duration of processing does not have a significant effect on the wear rate.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"33 31","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131501596","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":"Geodetic Measurement of Deformations of Load-Bearing Supports and Structures of the Komarovsky Market Building during its Operation","authors":"V. I. Mikhailov, N. O. Kuprienko","doi":"10.21122/2227-1031-2023-23-1-5-12","DOIUrl":"https://doi.org/10.21122/2227-1031-2023-23-1-5-12","url":null,"abstract":"Komarovsky market is the largest covered market in Belarus and Europe. It started working in 1980. Until 2000, the operation of the market building was carried out without taking into account the uniqueness and increased requirements for objects of such type. The technical conditions and operating rules for the precast-monolithic reinforced concrete pavement shell with dimensions of 103´103 m have not been met. This led to the fact that individual elements were in a pre-emergency state. Scientists and specialists of the Belarussian State Polytechnical Academy carried out work on the examination of the technical condition and operational suitability of the Komarovsky market building. It is recommended to carry out geodetic control of coating shell deflections, deformations of side elements and supports at least once a quarter. To do this, a geodetic planned and high-altitude justification was created along the perimeter of the market building and on its mezzanines, from which deformations of the coating shell and side elements were measured. Therefore, the height position of the mezzanines was checked by the class-IV leveling. For mathematical processing of the results of high-precision geodetic observations in the Visual Basic language of the Excel editor, a complex “Geodetic Programs” was compiled, which is located on the Belarusian National Technical University website and in the local network of the University. For 21 years, the software package has been used by the authors not only to solver scientific and production  problems, but also in the educational process. It is advisable to introduce programs in other educational institutions and industrial enterprises of the Republic of Belarus to solve the problems of engineering geodesy. The settlement measurements of the pile foundations of the market building were carried out by the class-II geometric leveling using КоNi 007 instrument. The coating shell deflections were determined by trigonometric leveling with a 2Т2 theodolite and a Leica TCR 1201 electronic tacheometer according special technique.  An accuracy of the order of 1–2 mm was ensured by short sighting beams. The displacements of the onboard elements were measured with a theodolite and electronic tacheometer using the polar method and circular technique. During the geodetic control, the measured values of deflections of the coating shell, deformations of the side elements and pile supports did not exceed the established tolerances, which indicates the stability of all load-bearing structures of the Komarovsky market building.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134090110","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":"Thermodynamic Evaluation of Asphalt Concrete Properties and its Mixing Energy Consumption by Exergy Structure","authors":"Qing Zhang, V. Romaniuk, B. Khroustalev, Q. Hou, Dehua Hou","doi":"10.21122/2227-1031-2023-23-1-34-41","DOIUrl":"https://doi.org/10.21122/2227-1031-2023-23-1-34-41","url":null,"abstract":" Abstract. The relevance of solving the problem of energy saving, today, is enhanced by the requirements of an environmental nature, united by the term “green energy”. Solving the problems of climate conservation is inseparable from solving the problem of energy saving.  Green, hydrogen energy, about which there has been a powerful and aggressive debate over the past decade, turned out to be directions far from solving the problems of both energy saving and environmental protection. The solution of both problems of energy saving and environmental protection at the present time and in the foreseeable future is being solved on the basis of the use of traditional primary energy resources, primarily natural gas. In this regard, the need to solve the problem of quantifying the thermodynamic perfection of heat-technological process for producing an asphalt concrete mixture becomes extremely relevant.  This assessment is most simply carried out on the basis of the exergy method of thermodynamic analysis with the determination of the exergy structure of  the asphalt concrete mixture flow, including thermomechanical, concentration and reaction components. The value of the concentration component of the exergy of the asphalt concrete mixture allows us to assess the energy efficiency of its production at asphalt concrete plants based on the modern exergy method of thermodynamic analysis; gives a quantitative estimate of the energy consumption for the process of mixing the ingredients of the asphalt concrete mixture in the mixing unit of asphalt concrete plants.  The paper defines the structure of the exergy of the asphalt concrete mixture, in which the transit reaction component dominates, which determines the specificity of the exergy of the asphalt concrete mixture.  The value of the specific mass concentration component of the exergy of the asphalt concrete mixture in comparison with the thermal component is small and the error in determining the concentration component, which cannot be objectively eliminated, does not affect the results of thermodynamic analysis.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114029521","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":"Comparative Study of Fiber Glass Reinforced Polymer and Carbon Fiber Reinforced Polymer on Cube and Cylinder","authors":"A. Al-obaidi, S. Leonovich","doi":"10.21122/2227-1031-2023-23-1-42-47","DOIUrl":"https://doi.org/10.21122/2227-1031-2023-23-1-42-47","url":null,"abstract":"A comparative analysis of polymers reinforced with glass fiber and polymers reinforced with carbon fiber was carried out on a cube and a cylinder in the laboratories of Baghdad.  36 samples were taken with fiber percentages of 1.0, 2.5 and 5.0 % by weight of cement. The methodology of this study included the use of composite polymer fibers in the external reinforcement of concrete beams for the purpose of improving their performance when bending by gluing polymer fibers to the surface.  Group A tests of non-reinforced concrete beams with other reinforced polymer fibers were also implemented. Excellent results were obtained by adding two types of polymer fibers to a concrete sample. It was found that the polymer reinforced with glass fiber showed better results than the polymer reinforced with carbon fiber when testing samples for bending strength.  However,  in splitting strength, the carbon fiber reinforced polymer achieved higher performance than the glass fiber reinforced polymer. Whereas the results of a group of previous studies conducted to study the effect of fiber additives on the mechanical properties of concrete proved that their addition led to an increase in compression, tensile and bending resistance at rates that reached 25, 75 and 80 %, respectively.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115105665","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":"Results of Many Years’ Measurements Conducted at the Czech State Long Distances Measuring Standard Koštice","authors":"N. Kosarev, J. Lechner, V. Padve, I. A. Umnov","doi":"10.21122/2227-1031-2023-23-1-13-19","DOIUrl":"https://doi.org/10.21122/2227-1031-2023-23-1-13-19","url":null,"abstract":"Currently, electronic total stations based on the principles of laser long-range distance measurement are used for collecting geospatial information. As time goes, in the process of using the electronic total stations, their technical parameters vary, necessitating periodic calibration of the instruments. Calibration of the long-range distance measurement laser component of the electronic total stations is carried out at specialized baselines and consists in testing the constant component of an electronic total station, determining the scale error and determining the cyclic error. In the territory of the Czech Republic, two geodetic baselines are operated, the National Calibration Baseline Hvězda and Koštice. Koštice is the Czech State Long Distances Measuring Standard, where electronic total stations are calibrated. From 2017 to 2020, about 600 electronic total stations by different manufacturers Leica Geosystems, Trimble, Topcon, Sokkia, Nikon, Pentax, South and Geomax were calibrated. The total number of measurements performed under the program in all combinations has equaled about 40000. In this paper, results of analysis many years’ measurements performed at the geodetic baseline Koštice from 2017 to 2020 with electronic total stations manufactured by Leica Geosystems are presented. In total, 9186 measurements between the baseline sections 1–2, 1–3, 1–4, 1–5, 1–6, 1–7 and 1–8 have been analyzed. For each section, measurements have been detected which did not pass the Grubbs test criterion (the Smirnov – Grubbs test). Altogether, 261 outliers have been detected, totaling 3 % of the total number of measurements. After excluding the detected outliers with the algorithm of the parametric version of least squares optimization, the length of each section of the baseline was found, and the accuracy of the results obtained was evaluated. The calculated values of the length of the baseline sections are in generally good agreement with the results of the measurements performed at the geodetic baseline Koštice by the specialists from the laboratory of the Bundeswehr University in Munich (Germany) and the results of similar measurements conducted at the same baseline by the specialists from the Research Institute of Geodesy, Topography and Cartography (Czech Republic). For section 1–5, based on the results of both verifications, differences have been obtained exceeding the permissible values of the accuracy of determining baseline characteristics. This may be related to the fact that there are displacements of certain pillars, which mainly have a periodic character and depend on the season. To allow more specific assumptions regarding instability of certain pillars, it is recommended to verify the lengths of the baseline sections once in three months, according to the program in all combinations, which will allow comparison of the values of the confidence limits of the baseline section lengths and putting forward hypotheses regarding variations in the p","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133256880","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":"Optimization of Composition of Nanofiber Concrete in Terms of Fracture Toughness by Matrix Modifiсation","authors":"E. Sadovskaya, S. Leonovich","doi":"10.21122/2227-1031-2022-21-6-499-503","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-6-499-503","url":null,"abstract":"Concrete is a quasi-brittle building material that has low tensile strength. The process of its destruction under loading is inhomogeneous, due to the nature of the concrete structure mass, consisting of components with different physical and mechanical properties. Gradual deformation and destruction can be characterized as a process of formation and development of microcracks. The presence of different-sized components in concrete makes it possible to consider its structure as a multi-level system. In this system, each level is a matrix with its own structural inclusions, which play both a structure-forming role and the role of stress concentrators under the action of mechanical loads. The critical stress intensity factor is a good indicator of the crack resistance (fracture toughness) of a material. Nanoconcrete, from the point of view of a multilevel system, is a concrete composite with crack propagation inhibitors at the level of the cementing substance (carbon nanotubes are consi-dered as inhibitors). The presence of fiber fibers at subsequent scale levels allows us to consider concrete as a composite with multi-level dispersed reinforcement (nanofiber concrete). The paper discusses the change of concrete fracture toughness indicator (crack resistance) with dispersed reinforcement of the matrix at different structural levels. The presented for normal separation of notched cubes under eccentric compression with the determination of the stress intensity factor for concrete modified with carbon nanotubes acting as crack propagation inhibitors at the level of cementing substance (nanoconcrete), as well as for nanofiber concrete with dispersed reinforcement at the level of fine-grained concrete. Based on experimental studies by non-equilibrium methods of fracture mechanics, compositions of nanofiber-reinforced concrete of maximum crack resistance (fracture toughness) with different fiber concentrations and several types of matrices modified with nanocarbon additives are proposed in the paper.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128869408","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":"Thermodynamic Approaches in Assessing Quality, Efficiency and Environmental Friendliness of Asphalt Concrete","authors":"Qing Zhang, V. Romaniuk, Y. Aliakseyeu, Q. Hou","doi":"10.21122/2227-1031-2022-21-6-490-498","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-6-490-498","url":null,"abstract":"The experience of developed countries shows that the development of the road network and transport infrastructure determines the intensity of economic ties and is one of the most important conditions for the development of the state’s economy. Optimization of the composition and production technology of asphalt concrete mixture – the basis of paved roads, is of great importance, both from an economic and environmental point of view. The production of asphalt concrete mixture directly (during the production process at asphalt concrete plants) and indirectly (during delivery from the plant to the place of installation) determines the energy costs for the production of asphalt concrete. At asphalt-concrete plants the specific energy consumption per ton of hot asphalt concrete mixture varies from 0.3 to 0.7 GJ. The range in energy costs is large. This situation indicates the presence of a significant energy-saving potential of asphalt concrete mixture thermal technology. The exergy analysis of technical systems proposed in this paper, which are operated in the asphalt concrete mixture production processes, makes it possible to judge the efficiency of energy use in their thermal units. This approach is expedient not only in the primary production of asphalt concrete mixture, but also for more environmentally friendly, energy- and resource-saving production processes for the operation of equipment during the regeneration of road asphalt concrete.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125945229","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":"Assessment of the Role of Human Resources in Enhancing Competitiveness of Industrial Organizations in the Transition to Industry 4.0","authors":"Minqjun Hu, I. V. Ustsinovich","doi":"10.21122/2227-1031-2022-21-6-525-534","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-6-525-534","url":null,"abstract":"In the conditions of necessity of transition to Industry 4.0 the human resource potential is considered as an important source of competitive advantage.  Only qualified personnel can make an organization competitive on the basis of market loyalty, product and service quality, differentiated products and technological innovation. Two directions for increasing the competitiveness of industrial enterprises have been identified. The first is the assessment of the system of indicators of human resource level during the transition to Industry 4.0. The second is to identify the most significant factors in assessing the level of human resources that affect the increase in the level of competitiveness of industrial organizations. The paper provides a detailed analysis of a number of economic indicators that characterize the integral indicator of the effectiveness of the human resources development and competitiveness of an industrial organization. The integral indicator has formed the basis of a model for assessing the competitiveness of industrial organizations through human resource development. The model consists of two parts: human resource development and the increase in the level of competitiveness of industrial organizations. The model is based on the following factors: the quality of human resources (staff composition of an industrial organization, the number of employees, their income level, education level, projects related to human resource development) and its development (total corporate income, share employee remuneration in the total organization income, R&D costs, the share of investment in R&D in the total organization income, sales and production). The developed model will allow organizations to adjust their human resource development strategies (recruitment and further development of human resources), and will also contribute to the transformation of corporate talent.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131614190","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}