M. N. Pokusaev, M. M. Gorbachev, Artem Maksimovich Gorbachev
{"title":"Cost-effectiveness of ships torsional vibrations monitoring systems application","authors":"M. N. Pokusaev, M. M. Gorbachev, Artem Maksimovich Gorbachev","doi":"10.24143/2073-1574-2024-1-64-71","DOIUrl":"https://doi.org/10.24143/2073-1574-2024-1-64-71","url":null,"abstract":"A torsional vibration monitoring system is being investigated, and an assessment of the economic efficiency of its implementation on ships is made. A schematic diagram of the torsional vibration monitoring system is illustrated and a photograph of an experimental sample of the monitoring system is provided. An assessment of the economic efficiency of the implementation of torsional vibration monitoring systems on ships is being carried out to prevent the occurrence of emergency situations with marine propulsion systems. The rules of classification societies, scientific and technical literature in the field of torsional oscillations and industrial economics, and the authors' own research were used as materials. The methods used are analysis and computational experiment. Data on the economic costs of the shipowner in the event of emergency situations in case of fatigue failures of elements of ship's engine and propulsion systems were obtained. An assessment of the costs for the development, installation and maintenance of a torsional vibration monitoring system on ships was made; as well as an approximate assessment of the volume of the Russian domestic market for installation and maintenance of torsional vibration monitoring systems on ships. It is noted that the cost of the consequences of propeller shaft failures ranges from several million to tens of millions of rubles. It is concluded that the development and implementation of torsional vibration monitoring systems will reduce the cost of the shipowner for a routine assessment of the technical condition of torsional vibration dampers and reduce the risks of costly accidents with shipboard engine complexes.","PeriodicalId":129911,"journal":{"name":"Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140414464","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}
Oleg Vladislavovich Savchenko, Mihail Yur'evich Khmel, Valery Nikolaevich Polovinkin, Igor Mihaylovich Kalinin
{"title":"Ship electric propulsion systems transformers: specific aspects of development","authors":"Oleg Vladislavovich Savchenko, Mihail Yur'evich Khmel, Valery Nikolaevich Polovinkin, Igor Mihaylovich Kalinin","doi":"10.24143/2073-1574-2024-1-112-120","DOIUrl":"https://doi.org/10.24143/2073-1574-2024-1-112-120","url":null,"abstract":"The necessity of new organizational and technical solutions in shipbuilding to ensure the quality of marine transformer transformers is substantiated. The analysis of the requirements of the Russian Maritime Register of Shipping, the current ISS for dry transformers is carried out, the experience of enterprises of related industries and foreign companies, the design features of power transformers of the ship's electric propulsion system are considered. The results of the analysis of the requirements for power transformers of marine electric propulsion systems, the features of their design and operation are presented. The main parameters of the converters in operating and emergency modes are considered and analyzed. The organizational and technical directions of ensuring increased reliability of marine converter transformers are proposed. Unlike converter transformers for land transport, there are no regulatory documents for power converter transformers in shipbuilding. The regulatory documents in force in shipbuilding do not fully take into account the specifics of marine conversion transformers. The existing main features of marine converter transformers are noted. High economic losses in the event of an accident of marine converter transformers determine higher requirements for their electrodynamic stability compared with converter transformers for land transport. In shipbuilding, there are no requirements for determining the partial short-circuit voltage and the splitting short-circuit voltage during testing of transformers necessary for the analysis of their characteristics and modes. When creating marine converter transformers, it is necessary to justify the characteristic modes of marine transformers using computer modeling, develop methods for measuring and calculating the parameters of selected modes and perform process calculations for the most likely accidents in the transformer – rectifier system. With the increase in the power of shipboard electric propulsion systems, the development of state regulatory documentation to ensure the quality of development and operation of converter transformers is becoming increasingly relevant.","PeriodicalId":129911,"journal":{"name":"Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies","volume":"11 17","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140409823","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}
Sergey Vasilevich Popov, O. A. Burmakin, Yuriy S. Malyshev
{"title":"Comparative analysis of the principles of high-speed vessels electrohydraulic steering machines construction","authors":"Sergey Vasilevich Popov, O. A. Burmakin, Yuriy S. Malyshev","doi":"10.24143/2073-1574-2024-1-104-111","DOIUrl":"https://doi.org/10.24143/2073-1574-2024-1-104-111","url":null,"abstract":"The composition and control principles of steering electro-hydraulic machines of a simple and follower type, intended for rudder shifting of small and high-speed vessels are considered. An analysis of the functioning of existing steering gears for the specified group of vessels was carried out. Deficiencies in the work associated with the element base and composition of the control and electric drive systems of the analyzed steering machines have been formed. The features of the operation of hydraulic systems with drive electric motors of pumps made on direct current, revealed as a result of experiments, are shown. Variants of technical solutions for improving the energy performance of the electric drive are proposed. A comparative analysis of the operation of steering machines with AC and DC drives has been carried out. An assessment of steering machines operation in normal and emergency modes is given. Structural diagrams of control systems of simple and follow-up action are proposed, taking into account the operating features identified during the analysis and the requirements of the Russian classification society. The possibility of implementing an SM electric drive built using a frequency converter – asynchronous motor system powered by an alternating current network and an emergency source has been shown. Options for the implementation of electric drives for pumps of hydraulic stations with a high-voltage battery are proposed. The possibility of creating domestic installations for steering and other ship mechanisms, according to the proposed structural diagrams of control systems for hydraulic stations for high-speed ships, is shown. Recommendations are given for the construction of steering gears for high-speed vessels with a total displacement of up to 100 tons using domestic electrical equipment.","PeriodicalId":129911,"journal":{"name":"Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140416106","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}
M. M. Gorbachev, Artem Vladislavovich Diachenko, Dmitriy Georgievich Konishchev, A. Kokuev
{"title":"Comparative assessment of micro-electromechanical accelerometers use for measuring torsional vibrations of marine propulsion systems","authors":"M. M. Gorbachev, Artem Vladislavovich Diachenko, Dmitriy Georgievich Konishchev, A. Kokuev","doi":"10.24143/2073-1574-2024-1-95-103","DOIUrl":"https://doi.org/10.24143/2073-1574-2024-1-95-103","url":null,"abstract":"Microelectromechanical accelerometers are investigated, and their applicability to measuring torsional vibrations occurring in marine propulsion systems is evaluated. The calculated and experimental assessment of the applicability of accelerometers of the ADXL345, ADXL375 and H3LIS331DL models for measuring torsional vibrations of marine shaft lines has been carried out and recommendations for their practical application have been developed. The materials used were the rules of the Russian Classification Society, scientific and technical literature in the field of torsional vibrations and the authors' own research. The methods used were analysis, numerical and physical experiment. Recommendations on the use of accelerometers of the ADXL345, ADXL375 and H3LIS331DL models depending on the rotational speed and diameter of the torsiographed shaft are obtained. The results obtained give grounds to recommend the ADXL375 accelerometer as the basic basic model for measuring torsional vibrations of most marine propulsion systems with rotation frequencies up to 1,025 min–1. At rotational speeds of less than 135 min–1, the use of the ADXL345 accelerometer with a measuring range of ±2g is recommended, and when setting the range of ±16g, it can be used at rotational speeds up to 380 min–1. If it is necessary to measure torsional vibrations at a rotational speed of more than 1,025 min–1, it is recommended to use a less accurate, but more reliable accelerometer model H3LIS331DL in terms of overload shutdown threshold.","PeriodicalId":129911,"journal":{"name":"Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies","volume":"2010 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140416538","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":"Sea transportation of Arctic oil for export","authors":"A. K. Voronenko","doi":"10.24143/2073-1574-2024-1-131-142","DOIUrl":"https://doi.org/10.24143/2073-1574-2024-1-131-142","url":null,"abstract":"The prospects for the development of transportation of crude oil from the Arctic shelf, incl. in the Eastern sector of the Russian Arctic are analyzed. Projects for the production and resources of hydrocarbons have been identified and mentioned ones will become the basis for the development of cargo transportation along the NSR in the medium and long term. The study of existing options for the transportation of hydrocarbons from the shelf of the Far East and the Russian Arctic showed the relevance of using schemes using shuttles and floating oil storage facilities. The expert approach identified the key groups of vessels necessary for the implementation of work on the shelf. The structure of fleet demand visualized in the article takes into account technologies for the development and maintenance of offshore hydrocarbon fields. As an example, the calculation of the required number of shuttles with transshipment through a floating oil storage facility or directly to the port of destination from an offshore ice-resistant fixed platform in key directions was made. The tanker Vasily Dinkov (Panamax type) and the tanker Gulf America (Aframax type) were used as prototypes. The key aspects that need to be taken into account when using the specified technological scheme of transportation are highlighted: ensuring year-round transportation; taking into account best practices and compatibility with existing schemes for the delivery of crude oil to the final ports of destination; optimal choice of transshipment points. It is also necessary to clarify the size groups of vessels on each of the routes and the size and type of floating oil storage facilities. Since the Arctic is a very sensitive area to the impact of the man-made environment, special attention is paid to environmental risks that increase with the intensification of navigation in the NSR water area.","PeriodicalId":129911,"journal":{"name":"Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies","volume":"16 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140411998","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":"Analysis by the information tools hierarchy method in providing cost calculations in civil shipbuilding","authors":"Anna V. Rodkina, Victor Alekseevich Kalmykov","doi":"10.24143/2073-1574-2024-1-38-44","DOIUrl":"https://doi.org/10.24143/2073-1574-2024-1-38-44","url":null,"abstract":"Currently, the development of shipbuilding is one of the critically important areas of Russia's industrial policy. According to the “Strategy for the development of the shipbuilding industry for the period up to 2035”, optimization of production facilities, their modernization and technical re-equipment, among others, are identified as its key tasks. The issue of digitalization of shipbuilding design is relevant, namely, the development and implementation of effective digital tools for the modernization and development of work on the design of shipbuilding facilities in terms of work on determining the cost of their construction and preparation of feasibility studies. The article considers the creation of a concept for the structure of digital tools to ensure the production of cost calculations in the process of designing civil shipbuilding facilities. A comprehensive analysis of the digitalization processes of the industry and the dynamics of the development of regulatory and methodological support for calculating the cost of designed products made it possible to formulate the key advantages of introducing digital technologies in the paradigm of digital transformation of shipbuilding, as well as to justify the expediency of searching and developing relevant digital tools in ensuring production processes in shipbuilding, in particular when preparing cost calculations for projected facilities. The choice of the most effective concept of an information tool in providing cost calculations for projected objects in the field of civil shipbuilding was carried out using the hierarchy analysis method. The criteria by which an effective alternative was chosen are formulated, three possible alternatives of an information tool in providing cost calculations for projected objects in the field of civil shipbuilding are considered.","PeriodicalId":129911,"journal":{"name":"Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies","volume":"90 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140414865","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}
Gennadiy Petrovich Kicha, Maksim Anatol'evich Serebryakov, Ruslan Alekseevich Kriuchkov, Andrey Veniaminovich Nadezhkin
{"title":"Modeling and evaluation of the engine oil aging intensity in marine trunk diesel engines when they are supercharged","authors":"Gennadiy Petrovich Kicha, Maksim Anatol'evich Serebryakov, Ruslan Alekseevich Kriuchkov, Andrey Veniaminovich Nadezhkin","doi":"10.24143/2073-1574-2024-1-45-57","DOIUrl":"https://doi.org/10.24143/2073-1574-2024-1-45-57","url":null,"abstract":"A computational and experimental model of the aging of lubricating oil in different directions is presented, taking into account the influence on the intensity of its degradation of the degree of forcing (thermal load) and the technical condition of diesel, the quality (motor group) of the lubricant product and the sulfur content in the fuel. The novelty in assessing the aging of the lubricant in a tank diesel engine when forcing it by supercharging consists in the formation of a thermal load on the oil film, which determines the aging rate of the engine oil on the cylinder sleeve of the engine. It is reported how the density of the heat flux acting on the surface of the oil film swept by the piston is experimentally fixed and averaged over the height of the sleeve and the angle of rotation of the crankshaft during the engine operating cycle. The influence of the factors under consideration on the specific rate of aging of lubricating oil per unit area of the sleeve surface in contact with gases in the direction of additive activation, decrease in alkalinity, increase in acidity, tar formation and accumulation of insoluble products has been identified. The lines of equal values of the hypersurfaces of the response functions for the specific intensity of the alkalinity response and the formation of insoluble products of tar formation and acidity growth are illustrated. The requirements for engine oil have been formed according to the level of alloying with multifunctional additives, depending on the degree of boost (average effective pressure) of supercharged marine tank diesels. As a result of the analysis of the aging rate of engine oil in modern marine diesel engines with medium and high boost, the expediency of using unified type oils in them has been confirmed M-10(14)G2CS and M-14(16)DCL20 with multifunctional additives MASK and PMS for the combustion of distillate fuels and their mixtures with fuel oils with a sulfur content of up to 0.5%.","PeriodicalId":129911,"journal":{"name":"Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies","volume":"5 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140408296","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}
Y. N. Tsvetkov, Ivan Evgen'evich Ivko, V. A. Petrov, Andrey Mihaylovich Oleynik
{"title":"The waterjet nozzle wear effect on jet pump performance","authors":"Y. N. Tsvetkov, Ivan Evgen'evich Ivko, V. A. Petrov, Andrey Mihaylovich Oleynik","doi":"10.24143/2073-1574-2024-1-7-14","DOIUrl":"https://doi.org/10.24143/2073-1574-2024-1-7-14","url":null,"abstract":"A finite-elemental model of a jet pump was created. The pump consisted of a case, in which there were eight jets, situated in a circle, symmetrically relative to the circle axis, on the equal distance of each other around the outlet of a pipeline, along which the pulp was pumped. The basic element size of the net in creating the model amounts to 50 mm, whereas the net elements size was diminished in the region of jets. The numerical experiment was carried out in order to evaluate the influence of the jets hydroabrasive wear parameters on the pump output. In conducting the computations, the assumptions were as follows: the liquid columns in the suction and force-feed pipelines were neglected; there was pure water modelled in the suction pipeline instead of the pulp taking into account that the concentration of the sand in the pulp does not exceed 10% by volume. The computations were realized in the stationary formulation of the problem. As basic parameters of the hydroabrasive wear of the jets the following were chosen: the angle of the skew of the jet forward end; a jet shortening – the displacement of the jet forward end center along the jet axis. As a result of the numerical experiment the body of data was obtained. Using the least squares method to process the data, the second order model was created, describing the dependence of the pump output on the jets wear parameters. The analysis of the model showed that the change of the angle of the forward end skew of the jets has a weak influence on the output of the pump, whereas the shortening of the jets by each millimeter causes the decrease of 1% to the nominal value of the pump output.","PeriodicalId":129911,"journal":{"name":"Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140414980","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}
D. Akmaykin, V. Grinyak, Viktoriya Valer'evna Bocharova, Oleg Alekseevich Bukin
{"title":"A method of satellite hydrometeorological information operational correction in a ship's navigation area using sub-satellite measurements","authors":"D. Akmaykin, V. Grinyak, Viktoriya Valer'evna Bocharova, Oleg Alekseevich Bukin","doi":"10.24143/2073-1574-2024-1-121-130","DOIUrl":"https://doi.org/10.24143/2073-1574-2024-1-121-130","url":null,"abstract":"The problem of assessing the state of the sea surface by combining satellite and ship measurements is considered. Information about the strength and direction of the wind at the sea surface is important to ensure safe navigation and planning of vessel transit routes. It is of key importance for weather forecasting and excitement. Wind data is traditionally obtained from passing ships and buoys. Ship data covers only limited areas of the World Ocean and is received unevenly, buoy data is highly sparse, which makes it impossible to obtain an adequate picture of the distribution of atmospheric currents. The use of remote sensing satellites has made it possible to increase the density of measurements of wind speed and direction by orders of magnitude, and the relevance of the data obtained. However, satellite measurements can be distorted. In particular, the influence of atmospheric precipitation (rain) can give a two-fold error in measuring wind speed. Strong and weak winds also create problems: in strong winds, the measured data underestimate the true wind speed, in weak winds they overestimate. A method for correcting satellite data on wind speed and direction is proposed. The essence of the method is to use subsatellite ship measurements in conjunction with satellite information. Knowing the weather data measured locally (from the ship), it is possible to calculate regression parameters for correcting satellite data. By applying regressions with calculated parameters to satellite images in the water area, it is possible to obtain more accurate weather data in the area of the vessel's route. The results of calculations based on real satellite and on-board data in the waters of the Sea of Okhotsk are presented. A polynomial of the second degree is taken as a regression function. It is shown that the correction using subsatellite ship measurements more accurately characterizes the wave than the data directly received from the satellite.","PeriodicalId":129911,"journal":{"name":"Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies","volume":"57 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140415012","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":"Theoretical determination of the mixer inner ring minimum allowable diameter to produce a two-phase mixture","authors":"E. G. Lebedeva","doi":"10.24143/2073-1574-2024-1-24-31","DOIUrl":"https://doi.org/10.24143/2073-1574-2024-1-24-31","url":null,"abstract":"When flushing marine systems and their components, a mixed flow of water and air can be used. This method of intensifying the flushing process of ship systems brings tangible results, but currently has a number of unresolved tasks. One of these tasks is the issue related to the risk of cavitation phenomena when using a two-phase mixture. The occurrence of cavitation depends on a number of factors, but primarily on the mass content of air in the water stream. An attempt has been made to assess the development of cavitation in the elements of a mixer used to produce a stable mixture of water and air. The design of the mixer is considered. The main theoretical dependence of the minimum allowable diameter of the narrow ring of the mixer on the main parameters of the mixed flow is determined: the densities of the phases of the mixture, the mass content of air in the stream, the initial diameter of the pipeline and the compression ratio of the jet in a narrow section, as well as on the initial pressure of the flushing flow. In the study of cavitation phenomena, a homogeneous model of a two-phase mixture was used as the most suitable for the flushing mode with a two-phase pulsating flow. The main calculation dependencies for determining the minimum allowable diameter of the narrow ring of the mixer are determined. The influence of various factors on the development of cavitation phenomena has been assessed. Recommendations are given on the choice of the diameter of the narrow ring of the mixer.","PeriodicalId":129911,"journal":{"name":"Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies","volume":"22 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140409338","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}