Pub Date : 2014-06-18DOI: 10.1109/SPEEDAM.2014.6872050
D. Baimel, R. Rabinovici, S. Tapuchi
The paper presents novel Phase Shifted PWM method for multi-level inverters operated in the over-modulation range. The proposed method is based on combination of Generic Phase Shifted PWM method with third harmonic injection method. The first significant advantage of the proposed method over the conventional Phase Disposition (PD) PWM is equal power flow between the H-bridges and almost equal distribution of the switching operations number between them. Furthermore, it provides improved linearity in the over-modulation range. The proposed method is analyzed by extensive simulation results. Several aspects as Total Harmonic Distortion Factor of the inverter output currents, and voltages, harmonic content, frequency spectrum distribution and switchings number are studied.
{"title":"Phase shifted PWM with third harmonic injection for over-modulation range operation","authors":"D. Baimel, R. Rabinovici, S. Tapuchi","doi":"10.1109/SPEEDAM.2014.6872050","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2014.6872050","url":null,"abstract":"The paper presents novel Phase Shifted PWM method for multi-level inverters operated in the over-modulation range. The proposed method is based on combination of Generic Phase Shifted PWM method with third harmonic injection method. The first significant advantage of the proposed method over the conventional Phase Disposition (PD) PWM is equal power flow between the H-bridges and almost equal distribution of the switching operations number between them. Furthermore, it provides improved linearity in the over-modulation range. The proposed method is analyzed by extensive simulation results. Several aspects as Total Harmonic Distortion Factor of the inverter output currents, and voltages, harmonic content, frequency spectrum distribution and switchings number are studied.","PeriodicalId":344918,"journal":{"name":"2014 International Symposium on Power Electronics, Electrical Drives, Automation and Motion","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129640799","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 : 2014-06-18DOI: 10.1109/SPEEDAM.2014.6871917
B. Deusinger, Marcel Lehr, A. Binder
The determination of the efficiency of electrical machines by direct measurements is often too imprecise if the efficiency exceeds 95 %. For electrically excited synchronous machines a standardized method exists to determine the efficiency by summation of the individual losses. This method needs a variable excitation and therefore cannot be used for permanent magnet synchronous machines. As permanent magnet machines are increasingly used as wind turbine generators and traction motors, there is a large demand for an alternative method. In this project a new procedure is developed, which consists of a calculation of the losses at rated conditions via three different measurement series. The corresponding losses and circuit diagram parameters are determined from measurements at open circuit, measurements with removed rotor and measurements with pure reactive current. In addition to the theoretical calculations direct efficiency measurements are used to validate the efficiency calculation results. The two examined permanent magnet motors with fractional slot winding have a rated power of 45 kW.
{"title":"Determination of efficiency of permanent magnet synchronous machines from summation of losses","authors":"B. Deusinger, Marcel Lehr, A. Binder","doi":"10.1109/SPEEDAM.2014.6871917","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2014.6871917","url":null,"abstract":"The determination of the efficiency of electrical machines by direct measurements is often too imprecise if the efficiency exceeds 95 %. For electrically excited synchronous machines a standardized method exists to determine the efficiency by summation of the individual losses. This method needs a variable excitation and therefore cannot be used for permanent magnet synchronous machines. As permanent magnet machines are increasingly used as wind turbine generators and traction motors, there is a large demand for an alternative method. In this project a new procedure is developed, which consists of a calculation of the losses at rated conditions via three different measurement series. The corresponding losses and circuit diagram parameters are determined from measurements at open circuit, measurements with removed rotor and measurements with pure reactive current. In addition to the theoretical calculations direct efficiency measurements are used to validate the efficiency calculation results. The two examined permanent magnet motors with fractional slot winding have a rated power of 45 kW.","PeriodicalId":344918,"journal":{"name":"2014 International Symposium on Power Electronics, Electrical Drives, Automation and Motion","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124579773","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 : 2014-06-18DOI: 10.1109/SPEEDAM.2014.6871913
M. Comanescu
The paper discusses the problem of estimating the speed, the flux magnitude and the rotor flux angle of the induction motor (IM) and presents an estimation method based on two Sliding Mode Observers (SMOs) and the Model Reference Adaptive System (MRAS) technique. The method is based on implementation of two SMOs that both yield the magnitude of the rotor flux; one observer is the reference model, the other is the adjustable model. The MRAS method is used to adapt the speed signal which is an input into both SMOs. The reference model is designed using the equations of the IM in the rotating reference frame. It is shown that its estimated flux magnitude is insensitive to the input speed. The adjustable model uses the IM equations in the stationary reference frame. Its output fluxes have magnitudes inverse proportional with the input speed; however, their phases are always accurate (this allows estimation of the flux angle). Using MRAS, the speed is corrected such that the flux magnitudes coming out of the two models match. Based on the structure developed, the paper also a speed estimation method. The simulations validate the theoretical development.
{"title":"An MRAS-type estimator for the speed, flux magnitude and rotor flux angle of the induction motor using sliding mode","authors":"M. Comanescu","doi":"10.1109/SPEEDAM.2014.6871913","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2014.6871913","url":null,"abstract":"The paper discusses the problem of estimating the speed, the flux magnitude and the rotor flux angle of the induction motor (IM) and presents an estimation method based on two Sliding Mode Observers (SMOs) and the Model Reference Adaptive System (MRAS) technique. The method is based on implementation of two SMOs that both yield the magnitude of the rotor flux; one observer is the reference model, the other is the adjustable model. The MRAS method is used to adapt the speed signal which is an input into both SMOs. The reference model is designed using the equations of the IM in the rotating reference frame. It is shown that its estimated flux magnitude is insensitive to the input speed. The adjustable model uses the IM equations in the stationary reference frame. Its output fluxes have magnitudes inverse proportional with the input speed; however, their phases are always accurate (this allows estimation of the flux angle). Using MRAS, the speed is corrected such that the flux magnitudes coming out of the two models match. Based on the structure developed, the paper also a speed estimation method. The simulations validate the theoretical development.","PeriodicalId":344918,"journal":{"name":"2014 International Symposium on Power Electronics, Electrical Drives, Automation and Motion","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134151488","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 : 2014-06-18DOI: 10.1109/SPEEDAM.2014.6871964
S. Atiq, T. Lipo, B. Kwon
Field weakening control is a key technique for high speed operation of electrical machines. A novel Current Regulated Voltage Source Inverter (CRVSI) operation strategy is adopted in this paper to achieve high speed operation from Surface Mounted Permanent Magnet Synchronous Motor (SMPMSM). This strategy avoids any kind of previously proposed winding switching and achieves same benefits of high flux weakening. Machine operation is divided into two modes: two 3-phase CRVSI operation and three single phase CRVSI operation. During first mode of operation machine can be operated at maximum torque conditions as well as d-axes current control is applied for first stage of flux weakening. In second mode of operation, when machine reaches its constant power operation limit, CRVSIs operation is modified. Three 1-phase CRVSI are established such that machine operation reverts to achieve unity internal power factor at the elevated speed. Again d-axes current control is adopted to achieve second stage of flux weakening. Suitability of suggested current flow paths for the proposed topology is supported by inductance variation calculations. Furthermore effect of slot per pole per phase configuration on this flux weakling topology is discussed. Also constant power capability of the machine is examined for high speed operation. Initial experimental results are provided to validate the simulation results.
{"title":"Novel field weakening technique for Surface Mounted Permanent Magnet machine using Current Regulated Voltage Source Inverters","authors":"S. Atiq, T. Lipo, B. Kwon","doi":"10.1109/SPEEDAM.2014.6871964","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2014.6871964","url":null,"abstract":"Field weakening control is a key technique for high speed operation of electrical machines. A novel Current Regulated Voltage Source Inverter (CRVSI) operation strategy is adopted in this paper to achieve high speed operation from Surface Mounted Permanent Magnet Synchronous Motor (SMPMSM). This strategy avoids any kind of previously proposed winding switching and achieves same benefits of high flux weakening. Machine operation is divided into two modes: two 3-phase CRVSI operation and three single phase CRVSI operation. During first mode of operation machine can be operated at maximum torque conditions as well as d-axes current control is applied for first stage of flux weakening. In second mode of operation, when machine reaches its constant power operation limit, CRVSIs operation is modified. Three 1-phase CRVSI are established such that machine operation reverts to achieve unity internal power factor at the elevated speed. Again d-axes current control is adopted to achieve second stage of flux weakening. Suitability of suggested current flow paths for the proposed topology is supported by inductance variation calculations. Furthermore effect of slot per pole per phase configuration on this flux weakling topology is discussed. Also constant power capability of the machine is examined for high speed operation. Initial experimental results are provided to validate the simulation results.","PeriodicalId":344918,"journal":{"name":"2014 International Symposium on Power Electronics, Electrical Drives, Automation and Motion","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131282611","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 : 2014-06-18DOI: 10.1109/SPEEDAM.2014.6871970
A. Mohammadpour, L. Parsa
An efficient analytical approach is proposed for design of fault-tolerant five-phase permanent-magnet direct-drive linear motor drives for reliability-critical applications. The proposed approach is based on shaping back EMF waveform through a simple closed-from analytical equation to achieve optimal design using a genetic algorithm based optimization. Magnet track and coil assembly parameters are optimized to have a sinusoidal back EMF waveform. Mathematical derivation of optimal fault-tolerant currents for ripple-free operation under open-circuit faults is presented. Proposed methodology can be used to design actuators for high-precision safety-critical applications. Finite-element-analysis and experimental test results are used to verify proposed design method.
{"title":"Optimal design and prototyping of a five-phase direct-drive permanent magnet linear motor","authors":"A. Mohammadpour, L. Parsa","doi":"10.1109/SPEEDAM.2014.6871970","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2014.6871970","url":null,"abstract":"An efficient analytical approach is proposed for design of fault-tolerant five-phase permanent-magnet direct-drive linear motor drives for reliability-critical applications. The proposed approach is based on shaping back EMF waveform through a simple closed-from analytical equation to achieve optimal design using a genetic algorithm based optimization. Magnet track and coil assembly parameters are optimized to have a sinusoidal back EMF waveform. Mathematical derivation of optimal fault-tolerant currents for ripple-free operation under open-circuit faults is presented. Proposed methodology can be used to design actuators for high-precision safety-critical applications. Finite-element-analysis and experimental test results are used to verify proposed design method.","PeriodicalId":344918,"journal":{"name":"2014 International Symposium on Power Electronics, Electrical Drives, Automation and Motion","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131367254","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 : 2014-06-18DOI: 10.1109/SPEEDAM.2014.6872008
A. C. Moreira, L. D. da Silva, H. K. Morales Paredes
This article proposes the use of PSCAD/EMTDC to model and simulate a three-phase x-ray machine. The model is an alternative tool to power quality studies, load connection impact analysis and power factor correction in the electric power distribution systems. The developed model is used to identify and quantify potential impacts of the X-ray machine in the electric power distribution system. Analyzes and discussions are based on actual measurements obtained in an X-ray apparatus terminals.
{"title":"Electrical modelling and power quality analysis of three-phase X-ray apparatus","authors":"A. C. Moreira, L. D. da Silva, H. K. Morales Paredes","doi":"10.1109/SPEEDAM.2014.6872008","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2014.6872008","url":null,"abstract":"This article proposes the use of PSCAD/EMTDC to model and simulate a three-phase x-ray machine. The model is an alternative tool to power quality studies, load connection impact analysis and power factor correction in the electric power distribution systems. The developed model is used to identify and quantify potential impacts of the X-ray machine in the electric power distribution system. Analyzes and discussions are based on actual measurements obtained in an X-ray apparatus terminals.","PeriodicalId":344918,"journal":{"name":"2014 International Symposium on Power Electronics, Electrical Drives, Automation and Motion","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133659127","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 : 2014-06-18DOI: 10.1109/SPEEDAM.2014.6871925
Masahiro Aoyama, T. Noguchi
This paper describes estimation of the rotor winding current based on a mathematical model of a self-excited wound-field synchronous motor where the space harmonics power is utilized for the field magnetization instead of the permanent magnets. The operation principle of the proposed motor is explicated by a voltage equation on the synchronous rotating reference frame. Furthermore, the rotor winding current is compared between the FEM based simulation and the mathematical calculation. Consequently, it has been confirmed that both operation characteristics in the steady state agree very well and indicate similar tendency.
{"title":"Estimation of rotor current based on mathematical model of wound-field synchronous motor self-excited by space harmonics","authors":"Masahiro Aoyama, T. Noguchi","doi":"10.1109/SPEEDAM.2014.6871925","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2014.6871925","url":null,"abstract":"This paper describes estimation of the rotor winding current based on a mathematical model of a self-excited wound-field synchronous motor where the space harmonics power is utilized for the field magnetization instead of the permanent magnets. The operation principle of the proposed motor is explicated by a voltage equation on the synchronous rotating reference frame. Furthermore, the rotor winding current is compared between the FEM based simulation and the mathematical calculation. Consequently, it has been confirmed that both operation characteristics in the steady state agree very well and indicate similar tendency.","PeriodicalId":344918,"journal":{"name":"2014 International Symposium on Power Electronics, Electrical Drives, Automation and Motion","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116263847","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 : 2014-06-18DOI: 10.1109/SPEEDAM.2014.6872083
F. Bizzozero, M. Giassi, G. Gruosso, S. Bozzi, G. Passoni
This paper presents a comparison among two types of linear generators for wave energy conversion: an inner-permanent-magnet-slotted-tubular-linear-generator (IPM-STLG) and an outer-permanent-magnet-slotless-tubular-linear-generator (OPM-STLG). The magnetic and electric quantities are extracted and evaluated using Finite Element Method Magnetics (FEMM) software and Matlab. These quantities include magnetic flux, cogging forces and end effects, inductances, currents, e.m.f., and power. In addition, a comparison of the two topologies and the different parameters has been performed. The aim of this work is to show a methodology to design Tubular linear generators for Sea Wave energy production, together with a comparison among different architectures.
{"title":"Dynamic model, parameter extraction, and analysis of two topologies of a tubular linear generator for seawave energy production","authors":"F. Bizzozero, M. Giassi, G. Gruosso, S. Bozzi, G. Passoni","doi":"10.1109/SPEEDAM.2014.6872083","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2014.6872083","url":null,"abstract":"This paper presents a comparison among two types of linear generators for wave energy conversion: an inner-permanent-magnet-slotted-tubular-linear-generator (IPM-STLG) and an outer-permanent-magnet-slotless-tubular-linear-generator (OPM-STLG). The magnetic and electric quantities are extracted and evaluated using Finite Element Method Magnetics (FEMM) software and Matlab. These quantities include magnetic flux, cogging forces and end effects, inductances, currents, e.m.f., and power. In addition, a comparison of the two topologies and the different parameters has been performed. The aim of this work is to show a methodology to design Tubular linear generators for Sea Wave energy production, together with a comparison among different architectures.","PeriodicalId":344918,"journal":{"name":"2014 International Symposium on Power Electronics, Electrical Drives, Automation and Motion","volume":"113 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124146314","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 : 2014-06-18DOI: 10.1109/SPEEDAM.2014.6871909
A. Gofuku, Yuta Okido, T. Yano
The authors have developed a spherical motor called as 14-12 spherical motor. The 14-12 spherical motor is composed of spherical rotor with permanent magnets, stator of spherical shell with electro-magnets, excitation electric circuit of electro-magnets, and power supply. The motor has two kinds of rotation axes and totally six rotation axes. The previous studies presented its structure, working principle of rotation by five-phase alternative current (AC), and experimental evaluation of rotation torque and cogging torque around one of rotation axes. This study evaluates the rotation torque around another rotation axis and cogging torque in detail to grasp the basic rotation performances of the 14-12 spherical motor.
{"title":"Evaluation of basic performances of a 14-12 spherical motor","authors":"A. Gofuku, Yuta Okido, T. Yano","doi":"10.1109/SPEEDAM.2014.6871909","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2014.6871909","url":null,"abstract":"The authors have developed a spherical motor called as 14-12 spherical motor. The 14-12 spherical motor is composed of spherical rotor with permanent magnets, stator of spherical shell with electro-magnets, excitation electric circuit of electro-magnets, and power supply. The motor has two kinds of rotation axes and totally six rotation axes. The previous studies presented its structure, working principle of rotation by five-phase alternative current (AC), and experimental evaluation of rotation torque and cogging torque around one of rotation axes. This study evaluates the rotation torque around another rotation axis and cogging torque in detail to grasp the basic rotation performances of the 14-12 spherical motor.","PeriodicalId":344918,"journal":{"name":"2014 International Symposium on Power Electronics, Electrical Drives, Automation and Motion","volume":"249 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124749631","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 : 2014-06-18DOI: 10.1109/SPEEDAM.2014.6872109
A. Brazhnikov, N. Dovzhenko, A. Minkin, O. Pomolotova, A. Litvinenko, Viktoriya A. Shilova
The prospects for the use of multiphase (i.e. having the number of phases more than four) asynchronous linear and non-linear drives in the field of vehicles were presented and described in a number of papers. However the increase of the phase number of asynchronous electric drive system allows not only to improve a number of its technical-and-economic characteristics, but also to create the hybrid traction drives according to scheme “AC Diesel-generator - Commutator - AC induction motor(s)” which will differ fundamentally from the existing ones, and have more simple design and less energy losses (in comparison with analogous existing hybrid drives). These AC hybrid traction drives of novel type are based on the use of the multiphase Diesel generators and non-traditional controlled multiphase induction motors.
{"title":"Multiphase hybrid traction drives for electrical vehicles","authors":"A. Brazhnikov, N. Dovzhenko, A. Minkin, O. Pomolotova, A. Litvinenko, Viktoriya A. Shilova","doi":"10.1109/SPEEDAM.2014.6872109","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2014.6872109","url":null,"abstract":"The prospects for the use of multiphase (i.e. having the number of phases more than four) asynchronous linear and non-linear drives in the field of vehicles were presented and described in a number of papers. However the increase of the phase number of asynchronous electric drive system allows not only to improve a number of its technical-and-economic characteristics, but also to create the hybrid traction drives according to scheme “AC Diesel-generator - Commutator - AC induction motor(s)” which will differ fundamentally from the existing ones, and have more simple design and less energy losses (in comparison with analogous existing hybrid drives). These AC hybrid traction drives of novel type are based on the use of the multiphase Diesel generators and non-traditional controlled multiphase induction motors.","PeriodicalId":344918,"journal":{"name":"2014 International Symposium on Power Electronics, Electrical Drives, Automation and Motion","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124208114","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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