Pub Date : 2019-06-01DOI: 10.1109/PEDG.2019.8807683
Dong Xu, Yong Shi, Jianhui Su, C. Feng
Voltage and frequency response model of microgrid system is an indispensable and key tool for designing secondary voltage frequency controller and analyzing voltage frequency stability of microgrid system. However, it is very laborious to build up the microgrid system model by mechanism modeling owing to the difficulty of obtaining the distributed generation (DG) model caused by the widespread use of commercial power supplies and other factors. If we adopt the method of identification modeling and regard the microgrid as a whole, we can see it as a black-box system with dual-input and dual-output, and the black-box identification modeling can be carried out only through the power reference data of the input port and the voltage and frequency data of the output port. At the same time, the recursive damped least squares method is used in model identification, so that online identification can be achieved. Simulation and experimental results show that, the proposed model can accurately reflect the voltage and frequency response characteristics of microgrid, thus verifying the validity of the proposed black-box identification modeling method.
{"title":"Identificaion Modeling Method of Voltage Frequency Response Model for Microgrid in Islanded Mode","authors":"Dong Xu, Yong Shi, Jianhui Su, C. Feng","doi":"10.1109/PEDG.2019.8807683","DOIUrl":"https://doi.org/10.1109/PEDG.2019.8807683","url":null,"abstract":"Voltage and frequency response model of microgrid system is an indispensable and key tool for designing secondary voltage frequency controller and analyzing voltage frequency stability of microgrid system. However, it is very laborious to build up the microgrid system model by mechanism modeling owing to the difficulty of obtaining the distributed generation (DG) model caused by the widespread use of commercial power supplies and other factors. If we adopt the method of identification modeling and regard the microgrid as a whole, we can see it as a black-box system with dual-input and dual-output, and the black-box identification modeling can be carried out only through the power reference data of the input port and the voltage and frequency data of the output port. At the same time, the recursive damped least squares method is used in model identification, so that online identification can be achieved. Simulation and experimental results show that, the proposed model can accurately reflect the voltage and frequency response characteristics of microgrid, thus verifying the validity of the proposed black-box identification modeling method.","PeriodicalId":248726,"journal":{"name":"2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128233021","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 : 2019-06-01DOI: 10.1109/PEDG.2019.8807483
Jinsong He, Xin Zhang
This paper proposed a modified Lyapunov-based control strategy for the three-phase UPS in d-q frame, which successfully solved the inherent steady-state error problem brought by standard Lyapunov-function based method. Continually, the third-order optimal load current observer in natural frame was designed to estimate the real-time load current, resulting in the omission of three load current sensors. Finally, experimental results validated the effectiveness and efficiency of proposed approach.
{"title":"A Modified Lyapunov-Based Control Scheme for a Three-phase UPS with an Optimal Third-order Load Current Observer","authors":"Jinsong He, Xin Zhang","doi":"10.1109/PEDG.2019.8807483","DOIUrl":"https://doi.org/10.1109/PEDG.2019.8807483","url":null,"abstract":"This paper proposed a modified Lyapunov-based control strategy for the three-phase UPS in d-q frame, which successfully solved the inherent steady-state error problem brought by standard Lyapunov-function based method. Continually, the third-order optimal load current observer in natural frame was designed to estimate the real-time load current, resulting in the omission of three load current sensors. Finally, experimental results validated the effectiveness and efficiency of proposed approach.","PeriodicalId":248726,"journal":{"name":"2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129329020","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}
The use of soft normally open point (SNOP) instead of the traditional tie switch can realize the closed-loop operation of the urban distribution network and realize the controllability of the transmission power of the feeder. In this paper, for the 10kV AC feeders of the urban distribution network, the SNOP composed of the back to back voltage source converter (B2B-VSC) is used to flexibly interconnect the two feeders, then, based on the droop control, an active power real-time modulation strategy based on power equalization technology is designed. The active power distribution coefficient is used to realize the active power deviation control of the feeders, and the load balance between the feeders is realized. The PSCAD/EMTDC simulation software was used to build a two-feeder distribution system using SNOP flexible interconnection, and the original dual-loop control strategy was improved by using power balance technology. The simulation results show that the active power real-time modulation strategy based on power equalization technology can balance the load between feeders in real-time under the condition of local control, and improve the utilization and operational reliability of feeder equipment.
{"title":"Research on Feeder Power Balancing Technology Based on SNOP Droop Control","authors":"Changbao Xu, Xufeng Yuan, Yutao Xu, Zhukui Tan, Chenghui Lin, Mingyang Chen","doi":"10.1109/PEDG.2019.8807466","DOIUrl":"https://doi.org/10.1109/PEDG.2019.8807466","url":null,"abstract":"The use of soft normally open point (SNOP) instead of the traditional tie switch can realize the closed-loop operation of the urban distribution network and realize the controllability of the transmission power of the feeder. In this paper, for the 10kV AC feeders of the urban distribution network, the SNOP composed of the back to back voltage source converter (B2B-VSC) is used to flexibly interconnect the two feeders, then, based on the droop control, an active power real-time modulation strategy based on power equalization technology is designed. The active power distribution coefficient is used to realize the active power deviation control of the feeders, and the load balance between the feeders is realized. The PSCAD/EMTDC simulation software was used to build a two-feeder distribution system using SNOP flexible interconnection, and the original dual-loop control strategy was improved by using power balance technology. The simulation results show that the active power real-time modulation strategy based on power equalization technology can balance the load between feeders in real-time under the condition of local control, and improve the utilization and operational reliability of feeder equipment.","PeriodicalId":248726,"journal":{"name":"2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129613832","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 : 2019-06-01DOI: 10.1109/PEDG.2019.8807507
Jie Ma, Changsheng Hu, W. Zhong, Dehong Xu
The volume of the passive components is one of the major challenges in designing a micro-inverter. To improve the power density of a micro-inverter, we propose an integrated structure of passive components including transformer and output filter with flexible multilayer foils (FMLF). The topology of the micro-inverter is modified to enable the integration of these passive components. In this paper, the design procedure of the integrated structure is explained. Finally, a prototype of the micro-inverter with the proposed integration is built to verify the design.
{"title":"An Integrated Structure for Transformer and Output Filter of a Micro-inverter with Flexible Multilayer Foil Technique","authors":"Jie Ma, Changsheng Hu, W. Zhong, Dehong Xu","doi":"10.1109/PEDG.2019.8807507","DOIUrl":"https://doi.org/10.1109/PEDG.2019.8807507","url":null,"abstract":"The volume of the passive components is one of the major challenges in designing a micro-inverter. To improve the power density of a micro-inverter, we propose an integrated structure of passive components including transformer and output filter with flexible multilayer foils (FMLF). The topology of the micro-inverter is modified to enable the integration of these passive components. In this paper, the design procedure of the integrated structure is explained. Finally, a prototype of the micro-inverter with the proposed integration is built to verify the design.","PeriodicalId":248726,"journal":{"name":"2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130180864","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}
In order to increase the mutual inductance between wireless charging coils of electric vehicles (EVs) and to improve the charging efficiency, the effect of magnetizer is analyzed by using the circuit theory. Based on planar spiral coils, three types of magnetizer structures, i.e. the disc types (including two structures) and the lampshade type, are designed in this paper. Moreover, four types of coils, one without magnetizers and three with three types of magnetizers, are simulated and compared using COMSOL. The magnetic flux density distribution diagrams of four types of coils and corresponding system transfer efficiencies are obtained. The simulation results show that: 1) magnetizers can help increase the magnetic flux passing through both transmitting and receiving coils and improve the wireless charging efficiency of EVs; 2) the length of magnetic circuit occupied by magnetizer should be increased as much as possible in the magnetizer structure design.
{"title":"Optimal Simulation Study for Wireless Charging Coils with Magnetizers","authors":"Xiangxiu Chen, Yanwei Liu, Wenzhou Lu, Yifan Dong, Haiying Chen","doi":"10.1109/PEDG.2019.8807519","DOIUrl":"https://doi.org/10.1109/PEDG.2019.8807519","url":null,"abstract":"In order to increase the mutual inductance between wireless charging coils of electric vehicles (EVs) and to improve the charging efficiency, the effect of magnetizer is analyzed by using the circuit theory. Based on planar spiral coils, three types of magnetizer structures, i.e. the disc types (including two structures) and the lampshade type, are designed in this paper. Moreover, four types of coils, one without magnetizers and three with three types of magnetizers, are simulated and compared using COMSOL. The magnetic flux density distribution diagrams of four types of coils and corresponding system transfer efficiencies are obtained. The simulation results show that: 1) magnetizers can help increase the magnetic flux passing through both transmitting and receiving coils and improve the wireless charging efficiency of EVs; 2) the length of magnetic circuit occupied by magnetizer should be increased as much as possible in the magnetizer structure design.","PeriodicalId":248726,"journal":{"name":"2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128814280","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 : 2019-06-01DOI: 10.1109/PEDG.2019.8807493
Shuai Zhang, G. Xiao, Chun He, C. Peng, Fujian Li, Xudong Du, Qilei Wang
Eelectric Vehicles (EVs) and photovoltaic system have developed fastly supported by governments to promote the popularization and application of new energy in recent years. As a important part in grid-connected converter, LCL output filter can filter out harmonics effectively compared to L filter. Reaearch on LCL filter is significant to achieve higher operating performance of grid-connected converter. Additional senssors sampling LCL component variables is introduced to realize the active damping in majority of application occasions. This paper introduce the analysis and design of the state observer of three phase PWM rectifier which is used in the charging and discharging system in electric vehicles firstly. Then, the principles of some conventional active damping control methods is introduced. On the basis of a power battery charging and discharging system prototype, a novel method based on state observer is proposed to realize the LCL filter control. This method can both avoid the aditional senssors and provide benefits for control of other circuit variables and over current protection. Besides, the simulation in IV used to verify the the correctness of theory analysis and active damping method design.
{"title":"A Improved Three Phase PWM Rectifier Active Damping Control Strategy With State Observer For Battery Charging And Discharging System","authors":"Shuai Zhang, G. Xiao, Chun He, C. Peng, Fujian Li, Xudong Du, Qilei Wang","doi":"10.1109/PEDG.2019.8807493","DOIUrl":"https://doi.org/10.1109/PEDG.2019.8807493","url":null,"abstract":"Eelectric Vehicles (EVs) and photovoltaic system have developed fastly supported by governments to promote the popularization and application of new energy in recent years. As a important part in grid-connected converter, LCL output filter can filter out harmonics effectively compared to L filter. Reaearch on LCL filter is significant to achieve higher operating performance of grid-connected converter. Additional senssors sampling LCL component variables is introduced to realize the active damping in majority of application occasions. This paper introduce the analysis and design of the state observer of three phase PWM rectifier which is used in the charging and discharging system in electric vehicles firstly. Then, the principles of some conventional active damping control methods is introduced. On the basis of a power battery charging and discharging system prototype, a novel method based on state observer is proposed to realize the LCL filter control. This method can both avoid the aditional senssors and provide benefits for control of other circuit variables and over current protection. Besides, the simulation in IV used to verify the the correctness of theory analysis and active damping method design.","PeriodicalId":248726,"journal":{"name":"2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":"108 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122265367","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 : 2019-06-01DOI: 10.1109/PEDG.2019.8807701
Lin Wang, Pengju Sun, Jie Wang, Kunlong Zhu, Tongyu Xue, Yuxin Zhang
Capacitive current feedback active damping is widely used in the LCL-type grid-connected inverter, which can effectively suppress the resonance peak of the system. However, the control delay in digital control system can change the characteristic of capacitive current feedback active damping and make the positive and negative boundary frequency of equivalent resistance is fs/6, which affects the stability of the grid-connected inverter and the robustness to grid impedance. At the same time, the control delay would introduce phase lag and limit the bandwidth of the control loop. Therefore, a delay compensation method considering both active damping characteristics and loop bandwidth is proposed, which can expand the boundary frequency to 0.43fs and greatly improve the robustness and dynamic performance of the system. Moreover, the sampling method is synchronous sampling, which strong switching-noise immunity. Simulation results verify the validity of the proposed method.
{"title":"A Delay Compensation Method to Improve the Current Control Performance of the LCL-Type Grid-Connected Inverter","authors":"Lin Wang, Pengju Sun, Jie Wang, Kunlong Zhu, Tongyu Xue, Yuxin Zhang","doi":"10.1109/PEDG.2019.8807701","DOIUrl":"https://doi.org/10.1109/PEDG.2019.8807701","url":null,"abstract":"Capacitive current feedback active damping is widely used in the LCL-type grid-connected inverter, which can effectively suppress the resonance peak of the system. However, the control delay in digital control system can change the characteristic of capacitive current feedback active damping and make the positive and negative boundary frequency of equivalent resistance is fs/6, which affects the stability of the grid-connected inverter and the robustness to grid impedance. At the same time, the control delay would introduce phase lag and limit the bandwidth of the control loop. Therefore, a delay compensation method considering both active damping characteristics and loop bandwidth is proposed, which can expand the boundary frequency to 0.43fs and greatly improve the robustness and dynamic performance of the system. Moreover, the sampling method is synchronous sampling, which strong switching-noise immunity. Simulation results verify the validity of the proposed method.","PeriodicalId":248726,"journal":{"name":"2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124731034","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 : 2019-06-01DOI: 10.1109/PEDG.2019.8807736
Guanhong Song, Bo Cao, Liuchen Chang, Riming Shao
In the past decades, renewable energy has been experiencing significant growth due to the increasing energy demand and critical environmental issues. In order to perform power conversion and grid integration for these distributed energy resources, grid-connected power converters are therefore widely used. In a typical three-phase grid-connected power converter, DC-link capacitors are normally used as an energy buffer to maintain a proper DC voltage for the power conversion. However, the DC-link voltage varies significantly when the input power from the distributed energy resources changes rapidly. Hence, a proper DC-link voltage controller is essential to perform fast DC-link voltage regulation. In this paper, a novel adaptive observer-based DC-link voltage control is proposed for three-phase grid-connected power converters to minimize the DC-link voltage fluctuation and to improve the stability of the state observer.
{"title":"A Novel Adaptive Observer-Based DC-Link Voltage Control for Grid-Connected Power Converters","authors":"Guanhong Song, Bo Cao, Liuchen Chang, Riming Shao","doi":"10.1109/PEDG.2019.8807736","DOIUrl":"https://doi.org/10.1109/PEDG.2019.8807736","url":null,"abstract":"In the past decades, renewable energy has been experiencing significant growth due to the increasing energy demand and critical environmental issues. In order to perform power conversion and grid integration for these distributed energy resources, grid-connected power converters are therefore widely used. In a typical three-phase grid-connected power converter, DC-link capacitors are normally used as an energy buffer to maintain a proper DC voltage for the power conversion. However, the DC-link voltage varies significantly when the input power from the distributed energy resources changes rapidly. Hence, a proper DC-link voltage controller is essential to perform fast DC-link voltage regulation. In this paper, a novel adaptive observer-based DC-link voltage control is proposed for three-phase grid-connected power converters to minimize the DC-link voltage fluctuation and to improve the stability of the state observer.","PeriodicalId":248726,"journal":{"name":"2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132498695","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}
Due to low on-state resistance and parasitic parameters, GaN devices can cause false triggering oscillation in practical systems that will affect system performance. In this paper, an RC snubber circuit is proposed to suppress false triggering oscillation in a half-bridge circuit and the design method of the RC parameters is proposed. The proposed oscillation suppression method is simpler, easier to implement, and more effective than the active gate driver. The proposed method is verified by experiment results. And it can provide guidance for oscillation suppression design in high-order systems.
{"title":"An RC Snubber Circuit to Suppress False Triggering Oscillation for GaN Based Half-Bridge Circuits","authors":"Jian Chen, Quanming Luo, Zhiqing Wang, Pengju Sun, Xiong Du, Yuqi Wei","doi":"10.1109/PEDG.2019.8807646","DOIUrl":"https://doi.org/10.1109/PEDG.2019.8807646","url":null,"abstract":"Due to low on-state resistance and parasitic parameters, GaN devices can cause false triggering oscillation in practical systems that will affect system performance. In this paper, an RC snubber circuit is proposed to suppress false triggering oscillation in a half-bridge circuit and the design method of the RC parameters is proposed. The proposed oscillation suppression method is simpler, easier to implement, and more effective than the active gate driver. The proposed method is verified by experiment results. And it can provide guidance for oscillation suppression design in high-order systems.","PeriodicalId":248726,"journal":{"name":"2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131928705","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 : 2019-06-01DOI: 10.1109/PEDG.2019.8807570
Han Li, Weimin Wu, Min Huang
Currently, Sliding Mode Control (SMC) controller based on global stability has been successfully applied to three-phase LCL-flltered Grid-Connected Inverter (GCI). However, to achieve the global stability of the system, all three state vectors are required to provide the full information, which would utilize many sensors, increasing the cost and complexity. In this paper, an observer-based SMC controller for three-phase LCL-flltered GCI is proposed. The discrete state observer is adopted to estimate the state vectors (inverter-side current and capacitor voltage) needed for the SMC controller. In addition, the detailed design of the SMC controller and the discrete state observer are introduced. The experimental results obtained from a 3kW system demonstrate the effectiveness of the proposed control strategy.
{"title":"Design of Observer-Based SMC Controller for Three-Phase LCL-Filtered Grid-Connected Inverters with Less Sensors","authors":"Han Li, Weimin Wu, Min Huang","doi":"10.1109/PEDG.2019.8807570","DOIUrl":"https://doi.org/10.1109/PEDG.2019.8807570","url":null,"abstract":"Currently, Sliding Mode Control (SMC) controller based on global stability has been successfully applied to three-phase LCL-flltered Grid-Connected Inverter (GCI). However, to achieve the global stability of the system, all three state vectors are required to provide the full information, which would utilize many sensors, increasing the cost and complexity. In this paper, an observer-based SMC controller for three-phase LCL-flltered GCI is proposed. The discrete state observer is adopted to estimate the state vectors (inverter-side current and capacitor voltage) needed for the SMC controller. In addition, the detailed design of the SMC controller and the discrete state observer are introduced. The experimental results obtained from a 3kW system demonstrate the effectiveness of the proposed control strategy.","PeriodicalId":248726,"journal":{"name":"2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG)","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133011466","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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