Pub Date : 2019-09-23DOI: 10.13052/ijfp1439-9776.2022
Paul Kalbfleisch, M. Ivantysynova
Many industries utilize axial piston machines for the compact design, highoperating pressures, variable displacements, and high efficiencies that faroutweigh the machines’ manufacturing costs. For all axial piston machines,the valve plate functions as an essential determinant of performance. Theaim of this research is to develop a design methodology generalizable to alltypes of valve plates while remaining accessible to users without advancedtechnical knowledge. The proposed design methodology is organized to fit theform of the standardized optimization problem statement. This organizationenables the use of any modern optimization algorithm. Specifically, the designmethodology utilizes a previously developed computer model, which is basedon the main physical phenomena influencing the design of flow passagesfrom the pump port to the displacement chambers and vice versa. The chosendesign methodology allows the precise optimization of the valve plate designby simulations rather than expensive trial and error processes. A recent casestudy demonstrated the strong positive correlation between application of themethodology and improved performance of the valve plate design.
{"title":"Computational Valve Plate Design in Axial Piston Pumps/Motors","authors":"Paul Kalbfleisch, M. Ivantysynova","doi":"10.13052/ijfp1439-9776.2022","DOIUrl":"https://doi.org/10.13052/ijfp1439-9776.2022","url":null,"abstract":"Many industries utilize axial piston machines for the compact design, highoperating pressures, variable displacements, and high efficiencies that faroutweigh the machines’ manufacturing costs. For all axial piston machines,the valve plate functions as an essential determinant of performance. Theaim of this research is to develop a design methodology generalizable to alltypes of valve plates while remaining accessible to users without advancedtechnical knowledge. The proposed design methodology is organized to fit theform of the standardized optimization problem statement. This organizationenables the use of any modern optimization algorithm. Specifically, the designmethodology utilizes a previously developed computer model, which is basedon the main physical phenomena influencing the design of flow passagesfrom the pump port to the displacement chambers and vice versa. The chosendesign methodology allows the precise optimization of the valve plate designby simulations rather than expensive trial and error processes. A recent casestudy demonstrated the strong positive correlation between application of themethodology and improved performance of the valve plate design.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44021766","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}
Pub Date : 2019-08-24DOI: 10.13052/ijfp1439-9776.2021
Li Tan, Haibo Xie, Jianbin Liu, Hanben Chen, Huayong Yang
This article mainly investigates how orifice structure influences the characteristics of steady-state flow force. The research model of this paper is originated from a cartridge proportional valve. Firstly, predicting characteristics of the flow force working on poppet in different types of orifice through CFD simulations; secondly, several parameters of poppet and seat, which may affect the characteristics of flow force, are defined, a series of CFD calculations were conducted to find a rule how each parameter influences flow force; thirdly, according to the analysis, optimization of orifice structure parameters has been successfully realized. Finally, a test bench was established to validate the simulation results. The results show that the orifice type has a significant influence on flow force, which indicates that choosing certain type of orifice can effectively decrease the influence of flow force, and the negative effect of flow force can be reduced within an acceptable extent. Besides, the influence of orifice on pressure difference has been also taken into account. The experimental results agree well with the simulative one.
{"title":"Research on Influence of Different types of Orifice on Axial Steady-state Flow Force in Cartridge Proportional Valve","authors":"Li Tan, Haibo Xie, Jianbin Liu, Hanben Chen, Huayong Yang","doi":"10.13052/ijfp1439-9776.2021","DOIUrl":"https://doi.org/10.13052/ijfp1439-9776.2021","url":null,"abstract":"This article mainly investigates how orifice structure influences the characteristics of steady-state flow force. The research model of this paper is originated from a cartridge proportional valve. Firstly, predicting characteristics of the flow force working on poppet in different types of orifice through CFD simulations; secondly, several parameters of poppet and seat, which may affect the characteristics of flow force, are defined, a series of CFD calculations were conducted to find a rule how each parameter influences flow force; thirdly, according to the analysis, optimization of orifice structure parameters has been successfully realized. Finally, a test bench was established to validate the simulation results. The results show that the orifice type has a significant influence on flow force, which indicates that choosing certain type of orifice can effectively decrease the influence of flow force, and the negative effect of flow force can be reduced within an acceptable extent. Besides, the influence of orifice on pressure difference has been also taken into account. The experimental results agree well with the simulative one.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46480794","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}
Pub Date : 2019-05-20DOI: 10.13052/IJFP1439-9776.2015
F. Messner, R. Scheidl
For many digital hydraulic systems, fast and precise valve actuation is a key to improve efficiency and performance. Such an actuation may be achieved by optimizing the valve design from a mechanical and hydraulically point of view. But additionally, power electronics for valve actuation has to be given also high attention since it can have significant influence on valve dynamics, particularly in case of high-speed actuation with switching times in the range of 1 ms or less. Such actuation poses requirements that are not met by standard power electronics. These requirements are analysed in this paper and a proper schematic for the power electronics is derived. Measurements with a corresponding prototype prove that a fast, precise and very repeatable valve actuation can be achieved if the power electronics is conceived according to the characteristics of high speed valves.
{"title":"Development of a Dual Supply H-Bridge Amplifier for High Speed Actuation of Digital Hydraulic Switching Valves","authors":"F. Messner, R. Scheidl","doi":"10.13052/IJFP1439-9776.2015","DOIUrl":"https://doi.org/10.13052/IJFP1439-9776.2015","url":null,"abstract":"For many digital hydraulic systems, fast and precise valve actuation is a key to improve efficiency and performance. Such an actuation may be achieved by optimizing the valve design from a mechanical and hydraulically point of view. But additionally, power electronics for valve actuation has to be given also high attention since it can have significant influence on valve dynamics, particularly in case of high-speed actuation with switching times in the range of 1 ms or less. Such actuation poses requirements that are not met by standard power electronics. These requirements are analysed in this paper and a proper schematic for the power electronics is derived. Measurements with a corresponding prototype prove that a fast, precise and very repeatable valve actuation can be achieved if the power electronics is conceived according to the characteristics of high speed valves.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66116626","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}
Pub Date : 2019-05-16DOI: 10.13052/IJFP1439-9776.2014
M. Linjama
This paper studies a variable speed drive with two hydraulic pump motors connected to an actuator. The torque load of the pump motors is reduced by connecting different pressures to the inlets of the pump motors. A method for real-time selection of the inlet pressures is developed. A linearized model is derived, and a robust control approach is used for the controller design of the variable speed drive. Simulation results indicate excellent controllability and robustness together with good energy efficiency. When three supply pressures — one being a pressurized tank line — are used, the peak torque is reduced by 52 per cent compared to the traditional solution.
{"title":"Variable speed drive with hydraulic boost","authors":"M. Linjama","doi":"10.13052/IJFP1439-9776.2014","DOIUrl":"https://doi.org/10.13052/IJFP1439-9776.2014","url":null,"abstract":"This paper studies a variable speed drive with two hydraulic pump motors connected to an actuator. The torque load of the pump motors is reduced by connecting different pressures to the inlets of the pump motors. A method for real-time selection of the inlet pressures is developed. A linearized model is derived, and a robust control approach is used for the controller design of the variable speed drive. Simulation results indicate excellent controllability and robustness together with good energy efficiency. When three supply pressures — one being a pressurized tank line — are used, the peak torque is reduced by 52 per cent compared to the traditional solution.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47549217","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}
Pub Date : 2019-04-18DOI: 10.13052/ijfp1439-9776.2011
J. Angerhausen, B. Persson, H. Murrenhoff, M. Scaraggi, L. Dorogin
Seals are crucial machine elements in hydraulic devices. However, especially with regard to dynamic seals – for example in cylinder applications – the physical understanding of the sealing mechanism is still insufficient. In this paper a physically based, transient elastohydrodynamic simulation for translational hydraulic seals is presented. The deformation of the seal is calculated in a dynamic finite element (FE) simulation, hyper- and viscoelastic material properties are taken into account. For the numerical calculation of the fluid film and its influences on the seal deformation the FE simulation is coupled with an implementation of the transient Reynold’s equation. For a physically based calculation of the solid contact, the FE-model is coupled with Persson’s theory of rubber friction and contact mechanics. Both, normal force and solid friction are implemented. In a simulation study the influence of the relative velocity in the contact between the elastic, highly deformable seal and a hard cylinder is investigated. The initial phase of motion is investigated in detail. The simulation results are compared to experimental data of a lubricated sliding contact between an nitrile butadiene rubber (NBR) O-ring and a rough steel surface.
{"title":"Finite Element based Transient Elastohydrodynamic Simulation of Translational Hydraulic Seals","authors":"J. Angerhausen, B. Persson, H. Murrenhoff, M. Scaraggi, L. Dorogin","doi":"10.13052/ijfp1439-9776.2011","DOIUrl":"https://doi.org/10.13052/ijfp1439-9776.2011","url":null,"abstract":"Seals are crucial machine elements in hydraulic devices. However, especially with regard to dynamic seals – for example in cylinder applications – the physical understanding of the sealing mechanism is still insufficient. In this paper a physically based, transient elastohydrodynamic simulation for translational hydraulic seals is presented. The deformation of the seal is calculated in a dynamic finite element (FE) simulation, hyper- and viscoelastic material properties are taken into account. For the numerical calculation of the fluid film and its influences on the seal deformation the FE simulation is coupled with an implementation of the transient Reynold’s equation. For a physically based calculation of the solid contact, the FE-model is coupled with Persson’s theory of rubber friction and contact mechanics. Both, normal force and solid friction are implemented. In a simulation study the influence of the relative velocity in the contact between the elastic, highly deformable seal and a hard cylinder is investigated. The initial phase of motion is investigated in detail. The simulation results are compared to experimental data of a lubricated sliding contact between an nitrile butadiene rubber (NBR) O-ring and a rough steel surface.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44644908","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}
Pub Date : 2018-10-30DOI: 10.1080/14399776.2018.1537456
P. Tamburrano, A. Plummer, E. Distaso, R. Amirante
This paper provides a review of the state of the art of electro-hydraulic servovalves, which are widely used valves in industrial applications and aerospace, being key components for closed loop electrohydraulic motion control systems. The paper discusses their operating principles and the analytical models used to study these valves. Commercially available units are also analysed in detail, reporting the performance levels achieved by current servovalves in addition to discussing their advantages and drawbacks. Adetailed analysis of research that investigates these valves via computational fluid dynamic analysis is also provided. Research studies on novel control systems and novel configurations based on the use of smart materials, wh
{"title":"A Review of Electro-Hydraulic Servovalve Research and Development","authors":"P. Tamburrano, A. Plummer, E. Distaso, R. Amirante","doi":"10.1080/14399776.2018.1537456","DOIUrl":"https://doi.org/10.1080/14399776.2018.1537456","url":null,"abstract":"This paper provides a review of the state of the art of electro-hydraulic servovalves, which are widely used valves in industrial applications and aerospace, being key components for closed loop electrohydraulic motion control systems. The paper discusses their operating principles and the analytical models used to study these valves. Commercially available units are also analysed in detail, reporting the performance levels achieved by current servovalves in addition to discussing their advantages and drawbacks. Adetailed analysis of research that investigates these valves via computational fluid dynamic analysis is also provided. Research studies on novel control systems and novel configurations based on the use of smart materials, wh","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2018-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/14399776.2018.1537456","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43313306","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}
Pub Date : 2018-10-29DOI: 10.1080/14399776.2018.1527122
K. Baer, Liselott Ericson, P. Krus
Hybridization of hydraulic drivetrains offers the potential of efficiency improvement for on- and off-road applications. To realize the advantages, a carefully designed system and corresponding control strategy are required, which are commonly obtained through a sequential design process.Addressing component selection and control parameterization simultaneously through simulation-based optimization allows for exploration of a large design space as well as design relations and trade-offs, and their evaluation in dynamic conditions which exist in real driving scenarios. In this paper, the optimization framework for a hydraulic hybrid vehicle is introduced, including the simulation model for a series hybrid architecture and component scaling considerations impacting the system’s performance.Anumber of optimization experiments for an on-road light-duty vehicle, focused on standard-drivecycle- performance, illustrate the impact of the problem formulation on the final design and thus the complexity of the design problem. The designs found demonstrate both the potential of energy storage in series hybrids, via an energy balance diagram, as well as some challenges. The framework presented here provides a base for systematic evaluation of design alternatives and problem formulation aspects.
{"title":"Framework for Simulation-Based Simultaneous System Optimization for a Series Hydraulic Hybrid Vehicle","authors":"K. Baer, Liselott Ericson, P. Krus","doi":"10.1080/14399776.2018.1527122","DOIUrl":"https://doi.org/10.1080/14399776.2018.1527122","url":null,"abstract":"Hybridization of hydraulic drivetrains offers the potential of efficiency improvement for on- and off-road applications. To realize the advantages, a carefully designed system and corresponding control strategy are required, which are commonly obtained through a sequential design process.Addressing component selection and control parameterization simultaneously through simulation-based optimization allows for exploration of a large design space as well as design relations and trade-offs, and their evaluation in dynamic conditions which exist in real driving scenarios. In this paper, the optimization framework for a hydraulic hybrid vehicle is introduced, including the simulation model for a series hybrid architecture and component scaling considerations impacting the system’s performance.Anumber of optimization experiments for an on-road light-duty vehicle, focused on standard-drivecycle- performance, illustrate the impact of the problem formulation on the final design and thus the complexity of the design problem. The designs found demonstrate both the potential of energy storage in series hybrids, via an energy balance diagram, as well as some challenges. The framework presented here provides a base for systematic evaluation of design alternatives and problem formulation aspects.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2018-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/14399776.2018.1527122","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45613527","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}
Pub Date : 2018-09-02DOI: 10.1080/14399776.2018.1514931
Jian-jun Hu, Zehe Yang, Zeng Huang, Yaolan Jin, Bin Yu, X. Kong
ABSTRACT In order to investigate the internal flow field characteristic for the pre-stage of jet pipe servo valve, a large-scale low-speed flow field visualisation experimental platform was developed. The internal flow field for the pre-stage of jet pipe servo valve was measured directly by particle image velocimetry (PIV), and its internal flow characteristics were obtained. The experimental results show that four vortices exist in the upper area and the lower area of the lower chamber of pre-stage. The upper chamber has two wide range of vortex in the pre-stage of jet pipe servo valve, and the vortex scale increases with the increase of flow rate. With the flow rate increases, the vortex in the upper area will disappear. The scale of the vortex in the lower area gradually increases with the increase of the flow rate, and the position gradually moves upwards. Under different deflection angles of jet pipe, the main characteristics of the vortex pre-stage are roughly the same, but the size and core of the vortex are different. The results provide a reference for the structural optimisation of the jet pipe servo valve.
{"title":"Flow measurement for the pre-stage of jet pipe servo valve using 2D -PIV technique","authors":"Jian-jun Hu, Zehe Yang, Zeng Huang, Yaolan Jin, Bin Yu, X. Kong","doi":"10.1080/14399776.2018.1514931","DOIUrl":"https://doi.org/10.1080/14399776.2018.1514931","url":null,"abstract":"ABSTRACT In order to investigate the internal flow field characteristic for the pre-stage of jet pipe servo valve, a large-scale low-speed flow field visualisation experimental platform was developed. The internal flow field for the pre-stage of jet pipe servo valve was measured directly by particle image velocimetry (PIV), and its internal flow characteristics were obtained. The experimental results show that four vortices exist in the upper area and the lower area of the lower chamber of pre-stage. The upper chamber has two wide range of vortex in the pre-stage of jet pipe servo valve, and the vortex scale increases with the increase of flow rate. With the flow rate increases, the vortex in the upper area will disappear. The scale of the vortex in the lower area gradually increases with the increase of the flow rate, and the position gradually moves upwards. Under different deflection angles of jet pipe, the main characteristics of the vortex pre-stage are roughly the same, but the size and core of the vortex are different. The results provide a reference for the structural optimisation of the jet pipe servo valve.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":"19 1","pages":"165 - 172"},"PeriodicalIF":0.8,"publicationDate":"2018-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/14399776.2018.1514931","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44776459","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}
Pub Date : 2018-09-02DOI: 10.1080/14399776.2018.1516061
Nathan Keller
The exponential integration of renewable energy sources into smart power generation and distribution networks (SMART GRID) has positive ecological effects but generates major frequency regulation problems that can only be solved by conventional hydroelectric power stations and those with pumping accumulation. In this context, starting from the requirements of the energy systems and the producers of classical and reversible hydraulic turbines, the author approached, with the modern instruments of system theory, the conception, design, modelling, simulation and experimental identification of electrohydraulic servovalves, which are the fundamental components of the systems adjusting the speed and power of hydropower units and other major hydromechanical equipment: valves, rails, gateways, etc. The practical aim of the thesis is the elaboration of a systemic procedure for designing prototypes of industrial digital servovalve suitable for all types of hydroelectric power plants with power between 10 kW and 1000 MW. This range of power requires families of single-stage, two-stage and three-stage servovalves, built entirely based on the author’s design. To facilitate the integration of new servovalves into complex digital automated systems, the studied mathematical models were transformed into subroutines compatible with the numerical simulation analysis programme of the technical systems Simcenter Amesim, greatly simplifying their optimal synthesis. The identification of the equipment and systems studied in the thesis was conducted with experimental data acquisition interfaces PXI produced by NI CORPORATION, assisted by the LabVIEW software package. The author has patented a new technical design of a three-stage electro hydraulic servovalve and applied it for the refurbishment of INGA POWER STATION from CONGO RIVER. Adrien Monsimer
{"title":"PhD theses completed in 2018","authors":"Nathan Keller","doi":"10.1080/14399776.2018.1516061","DOIUrl":"https://doi.org/10.1080/14399776.2018.1516061","url":null,"abstract":"The exponential integration of renewable energy sources into smart power generation and distribution networks (SMART GRID) has positive ecological effects but generates major frequency regulation problems that can only be solved by conventional hydroelectric power stations and those with pumping accumulation. In this context, starting from the requirements of the energy systems and the producers of classical and reversible hydraulic turbines, the author approached, with the modern instruments of system theory, the conception, design, modelling, simulation and experimental identification of electrohydraulic servovalves, which are the fundamental components of the systems adjusting the speed and power of hydropower units and other major hydromechanical equipment: valves, rails, gateways, etc. The practical aim of the thesis is the elaboration of a systemic procedure for designing prototypes of industrial digital servovalve suitable for all types of hydroelectric power plants with power between 10 kW and 1000 MW. This range of power requires families of single-stage, two-stage and three-stage servovalves, built entirely based on the author’s design. To facilitate the integration of new servovalves into complex digital automated systems, the studied mathematical models were transformed into subroutines compatible with the numerical simulation analysis programme of the technical systems Simcenter Amesim, greatly simplifying their optimal synthesis. The identification of the equipment and systems studied in the thesis was conducted with experimental data acquisition interfaces PXI produced by NI CORPORATION, assisted by the LabVIEW software package. The author has patented a new technical design of a three-stage electro hydraulic servovalve and applied it for the refurbishment of INGA POWER STATION from CONGO RIVER. Adrien Monsimer","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":"19 1","pages":"174 - 174"},"PeriodicalIF":0.8,"publicationDate":"2018-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/14399776.2018.1516061","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48386749","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}
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