Pub Date : 2024-03-01DOI: 10.30941/CESTEMS.2024.00006
G. Kovács
The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an attempt to fill this gap in the previous parts of our study by elaborating formulas for calculation of parasitic torques. It was a general demand among those who work in this field towards the author to verify his formulas with measurements. In the literature, it seems, only one detailed, purposeful series of measurements has been published so far, the purpose of which was to investigate the effect of the number of rotor slots on the torque-speed characteristic curve of the machine. The main goal of this study is to verify the correctness of the formulas by comparing them with the referred series of measurements. Relying on this, the expected synchronous parasitic torques were developed for the frequently used rotor slot numbers - as a design guide for the engineer. Thus, together with our complete table for radial magnetic pull published in our previous work, the designer has all the principles, data and formulas available for the right number of rotor slots for his given machine and for the drive system. This brings this series of papers to an end.
{"title":"Harmonics in the Squirrel Cage Induction Motor Analytic Calculation Part III: Influence on the Torque-speed Characteristic","authors":"G. Kovács","doi":"10.30941/CESTEMS.2024.00006","DOIUrl":"https://doi.org/10.30941/CESTEMS.2024.00006","url":null,"abstract":"The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an attempt to fill this gap in the previous parts of our study by elaborating formulas for calculation of parasitic torques. It was a general demand among those who work in this field towards the author to verify his formulas with measurements. In the literature, it seems, only one detailed, purposeful series of measurements has been published so far, the purpose of which was to investigate the effect of the number of rotor slots on the torque-speed characteristic curve of the machine. The main goal of this study is to verify the correctness of the formulas by comparing them with the referred series of measurements. Relying on this, the expected synchronous parasitic torques were developed for the frequently used rotor slot numbers - as a design guide for the engineer. Thus, together with our complete table for radial magnetic pull published in our previous work, the designer has all the principles, data and formulas available for the right number of rotor slots for his given machine and for the drive system. This brings this series of papers to an end.","PeriodicalId":100229,"journal":{"name":"CES Transactions on Electrical Machines and Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10488426","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140342750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, the electromagnetic performance of variable flux memory (VFM) machines with series-magnetic-circuit is investigated and compared for different rotor topologies. Based on a V-type VFM machine, five topologies with different interior permanent magnet (IPM) arrangements are evolved and optimized under same constrains. Based on two-dimensional (2-D) finite element (FE) method, their electromagnetic performance at magnetization and demagnetization states is evaluated. It reveals that the iron bridge and rotor lamination region between constant PM (CPM) and variable PM (VPM) play an important role in torque density and flux regulation (FR) capabilities. Besides, the global efficiency can be improved in VFM machines by adjusting magnetization state (MS) under different operating conditions.
本文研究并比较了不同转子拓扑结构的串联磁路可变磁通记忆（VFM）机器的电磁性能。以 V 型变磁通量记忆机为基础，在相同的约束条件下演化并优化了五种具有不同内部永磁体 (IPM) 布置的拓扑结构。基于二维（2-D）有限元（FE）方法，对它们在磁化和退磁状态下的电磁性能进行了评估。结果表明，恒定永磁发电机（CPM）和可变永磁发电机（VPM）之间的铁桥和转子叠片区域对转矩密度和磁通调节（FR）能力起着重要作用。此外，在不同的运行条件下，通过调整磁化状态（MS），可提高变频调速器的整体效率。
{"title":"Electromagnetic Performance Analysis of Variable Flux Memory Machines with Series-magnetic-circuit and Different Rotor Topologies","authors":"Qiang Wei;Z.Q. Zhu;Yan Jia;Jianghua Feng;Shuying Guo;Yifeng Li;Shouzhi Feng","doi":"10.30941/CESTEMS.2024.00012","DOIUrl":"https://doi.org/10.30941/CESTEMS.2024.00012","url":null,"abstract":"In this paper, the electromagnetic performance of variable flux memory (VFM) machines with series-magnetic-circuit is investigated and compared for different rotor topologies. Based on a V-type VFM machine, five topologies with different interior permanent magnet (IPM) arrangements are evolved and optimized under same constrains. Based on two-dimensional (2-D) finite element (FE) method, their electromagnetic performance at magnetization and demagnetization states is evaluated. It reveals that the iron bridge and rotor lamination region between constant PM (CPM) and variable PM (VPM) play an important role in torque density and flux regulation (FR) capabilities. Besides, the global efficiency can be improved in VFM machines by adjusting magnetization state (MS) under different operating conditions.","PeriodicalId":100229,"journal":{"name":"CES Transactions on Electrical Machines and Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10488427","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140342667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-01DOI: 10.30941/CESTEMS.2024.00005
Ze-Zheng Wu;Robert Nilssen;Jian-Xin Shen
A versatile analytical method (VAM) for calculating the harmonic components of the magneto-motive force (MMF) generated by diverse armature windings in AC machines has been proposed, and the versatility of this method has been established in early literature. However, its practical applications and significance in advancing the analysis of AC machines need further elaboration. This paper aims to complement VAM by augmenting its theory, offering additional insights into its conclusions, as well as demonstrating its utility in assessing armature windings and its application of calculating torque for permanent magnet synchronous machines (PMSM). This work contributes to advancing the analysis of AC machines and underscores the potential for improved design and performance optimization.
{"title":"Utility and Application of a Versatile Analytical Method for MMF Calculation in AC Machines","authors":"Ze-Zheng Wu;Robert Nilssen;Jian-Xin Shen","doi":"10.30941/CESTEMS.2024.00005","DOIUrl":"https://doi.org/10.30941/CESTEMS.2024.00005","url":null,"abstract":"A versatile analytical method (VAM) for calculating the harmonic components of the magneto-motive force (MMF) generated by diverse armature windings in AC machines has been proposed, and the versatility of this method has been established in early literature. However, its practical applications and significance in advancing the analysis of AC machines need further elaboration. This paper aims to complement VAM by augmenting its theory, offering additional insights into its conclusions, as well as demonstrating its utility in assessing armature windings and its application of calculating torque for permanent magnet synchronous machines (PMSM). This work contributes to advancing the analysis of AC machines and underscores the potential for improved design and performance optimization.","PeriodicalId":100229,"journal":{"name":"CES Transactions on Electrical Machines and Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10488428","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140342732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-01DOI: 10.30941/CESTEMS.2024.00010
Xiaoshuang Hui;Puqi Ning;Tao Fan;Yuhui Kang;Kai Wang;Yunhui Mei;Guangyin Lei
Silicon carbide (SiC) power modules play an essential role in the electric vehicle drive system. To improve their performance, reduce their size, and increase production efficiency, this paper proposes a multiple staked direct bonded copper (DBC) unit based power module packaging method to parallel more chips. This method utilizes mutual inductance cancellation effect to reduce parasitic inductance. Because the conduction area in the new package is doubled, the overall area of power module can be reduced. Entire power module is divided into smaller units to enhance manufacture yield, and improve design freedom. This paper provides a detailed design, analysis and fabrication procedure for the proposed package structure. Additionally, this paper offers several feasible solutions for the connection between power terminals and DBC untis. With the structure, 18 dies were paralleled for each phase-leg in a econodual size power module. Both simulation and double pulse test results demonstrate that, compared to conventional layouts, the proposed package method has 74.8% smaller parasitic inductance and 34.9% lower footprint.
{"title":"A Novel Multiple DBC-staked units Package to Parallel More Chips for SiC Power Module","authors":"Xiaoshuang Hui;Puqi Ning;Tao Fan;Yuhui Kang;Kai Wang;Yunhui Mei;Guangyin Lei","doi":"10.30941/CESTEMS.2024.00010","DOIUrl":"https://doi.org/10.30941/CESTEMS.2024.00010","url":null,"abstract":"Silicon carbide (SiC) power modules play an essential role in the electric vehicle drive system. To improve their performance, reduce their size, and increase production efficiency, this paper proposes a multiple staked direct bonded copper (DBC) unit based power module packaging method to parallel more chips. This method utilizes mutual inductance cancellation effect to reduce parasitic inductance. Because the conduction area in the new package is doubled, the overall area of power module can be reduced. Entire power module is divided into smaller units to enhance manufacture yield, and improve design freedom. This paper provides a detailed design, analysis and fabrication procedure for the proposed package structure. Additionally, this paper offers several feasible solutions for the connection between power terminals and DBC untis. With the structure, 18 dies were paralleled for each phase-leg in a econodual size power module. Both simulation and double pulse test results demonstrate that, compared to conventional layouts, the proposed package method has 74.8% smaller parasitic inductance and 34.9% lower footprint.","PeriodicalId":100229,"journal":{"name":"CES Transactions on Electrical Machines and Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10488430","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140342751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-01DOI: 10.30941/CESTEMS.2024.00000
IN recent years, the electrical machines and systems have grown so rapidly with more and more applications in emerging civilian industries as well as cutting-edge areas. A group of novel and exciting technologies have been developed every year. First, the research of motors in new and extreme fields have constantly brought amazing progress to achieve better performance through new technologies such as digitalization, etc. Meanwhile, the fast development of power electronics in recent decades has also changed the overall system to be more flexible, and widely extent our boundary of research area. What is more, the advancing technologies such as information technology, new energy technology, artificial intelligence technology, etc., have shown their potential roles in this area, bringing more opportunities but more technique challenges as well. It was the best of times, it was the worst of times. At this point, we would like to share these most insightful ideas and progress to our peers. For this reason, CES TEMS promoted this new column Frontier.
{"title":"Message from Editors","authors":"","doi":"10.30941/CESTEMS.2024.00000","DOIUrl":"https://doi.org/10.30941/CESTEMS.2024.00000","url":null,"abstract":"IN recent years, the electrical machines and systems have grown so rapidly with more and more applications in emerging civilian industries as well as cutting-edge areas. A group of novel and exciting technologies have been developed every year. First, the research of motors in new and extreme fields have constantly brought amazing progress to achieve better performance through new technologies such as digitalization, etc. Meanwhile, the fast development of power electronics in recent decades has also changed the overall system to be more flexible, and widely extent our boundary of research area. What is more, the advancing technologies such as information technology, new energy technology, artificial intelligence technology, etc., have shown their potential roles in this area, bringing more opportunities but more technique challenges as well. It was the best of times, it was the worst of times. At this point, we would like to share these most insightful ideas and progress to our peers. For this reason, CES TEMS promoted this new column Frontier.","PeriodicalId":100229,"journal":{"name":"CES Transactions on Electrical Machines and Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10488441","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140342764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Here, we introduce a partitioned design method that is oriented toward airgap harmonic for permanent magnet vernier (PMV) motors. The method proposes the utilization of airgap flux harmonics as an effective bridge between the torque design region and the torque performances. To illustrate the efficacy of this method, a partitioned design PMV motor is presented and compared with the initial design. Firstly, the torque design region of the rotor is artfully divided into the torque enhancement region and ripple reduction region. Meanwhile, the main harmonics that generate output torque are chosen and enhanced, optimization. Moreover, the harmonics that generate torque ripple are selected and reduced based on torque harmonics optimization. Finally, the functions of the partitioned PMV motor torque are assessed based on the finite element method. By the purposeful design of these two regions, the output torque is strengthened while torque ripple is inhibited effectively, verifying the effectiveness and reasonability of the proposed design method.
{"title":"Airgap-Harmonic-Oriented Partitioned Design Method of PMV Motor with Improved Torque Performances","authors":"Zhaopeng Wu;Li Quan;Zixuan Xiang;Deyang Fan;Tengguang Wang;Xiaoyong Zhu","doi":"10.30941/CESTEMS.2024.00002","DOIUrl":"https://doi.org/10.30941/CESTEMS.2024.00002","url":null,"abstract":"Here, we introduce a partitioned design method that is oriented toward airgap harmonic for permanent magnet vernier (PMV) motors. The method proposes the utilization of airgap flux harmonics as an effective bridge between the torque design region and the torque performances. To illustrate the efficacy of this method, a partitioned design PMV motor is presented and compared with the initial design. Firstly, the torque design region of the rotor is artfully divided into the torque enhancement region and ripple reduction region. Meanwhile, the main harmonics that generate output torque are chosen and enhanced, optimization. Moreover, the harmonics that generate torque ripple are selected and reduced based on torque harmonics optimization. Finally, the functions of the partitioned PMV motor torque are assessed based on the finite element method. By the purposeful design of these two regions, the output torque is strengthened while torque ripple is inhibited effectively, verifying the effectiveness and reasonability of the proposed design method.","PeriodicalId":100229,"journal":{"name":"CES Transactions on Electrical Machines and Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10452308","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140342765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The noise that comes from finite element simulation often causes the model to fall into the local optimal solution and over fitting during optimization of generator. Thus, this paper proposes a Gaussian Process Regression (GPR) model based on Conditional Likelihood Lower Bound Search (CLLBS) to optimize the design of the generator, which can filter the noise in the data and search for global optimization by combining the Conditional Likelihood Lower Bound Search method. Taking the efficiency optimization of 15 kW Permanent Magnet Synchronous Motor as an example. Firstly, this method uses the elementary effect analysis to choose the sensitive variables, combining the evolutionary algorithm to design the super Latin cube sampling plan; Then the generator-converter system is simulated by establishing a co-simulation platform to obtain data. A Gaussian process regression model combing the method of the conditional likelihood lower bound search is established, which combined the chi-square test to optimize the accuracy of the model globally. Secondly, after the model reaches the accuracy, the Pareto frontier is obtained through the NSGA-II algorithm by considering the maximum output torque as a constraint. Last, the constrained optimization is transformed into an unconstrained optimizing problem by introducing maximum constrained improvement expectation (CEI) optimization method based on the re-interpolation model, which cross-validated the optimization results of the Gaussian process regression model. The above method increase the efficiency of generator by 0.76% and 0.5% respectively; And this method can be used for rapid modeling and multi-objective optimization of generator systems.
{"title":"Optimization of Generator Based on Gaussian Process Regression Model with Conditional Likelihood Lower Bound Search","authors":"Xiao Liu;Pingting Lin;Fan Bu;Shaoling Zhuang;Shoudao Huang","doi":"10.30941/CESTEMS.2024.00001","DOIUrl":"https://doi.org/10.30941/CESTEMS.2024.00001","url":null,"abstract":"The noise that comes from finite element simulation often causes the model to fall into the local optimal solution and over fitting during optimization of generator. Thus, this paper proposes a Gaussian Process Regression (GPR) model based on Conditional Likelihood Lower Bound Search (CLLBS) to optimize the design of the generator, which can filter the noise in the data and search for global optimization by combining the Conditional Likelihood Lower Bound Search method. Taking the efficiency optimization of 15 kW Permanent Magnet Synchronous Motor as an example. Firstly, this method uses the elementary effect analysis to choose the sensitive variables, combining the evolutionary algorithm to design the super Latin cube sampling plan; Then the generator-converter system is simulated by establishing a co-simulation platform to obtain data. A Gaussian process regression model combing the method of the conditional likelihood lower bound search is established, which combined the chi-square test to optimize the accuracy of the model globally. Secondly, after the model reaches the accuracy, the Pareto frontier is obtained through the NSGA-II algorithm by considering the maximum output torque as a constraint. Last, the constrained optimization is transformed into an unconstrained optimizing problem by introducing maximum constrained improvement expectation (CEI) optimization method based on the re-interpolation model, which cross-validated the optimization results of the Gaussian process regression model. The above method increase the efficiency of generator by 0.76% and 0.5% respectively; And this method can be used for rapid modeling and multi-objective optimization of generator systems.","PeriodicalId":100229,"journal":{"name":"CES Transactions on Electrical Machines and Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10452307","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140342669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-28DOI: 10.30941/CESTEMS.2023.00048
A. Infantraj;M. Augustine;E. Fantin Irudaya Raj;M. Appadurai
Permanent magnet brushless DC motors are used for various low-power applications, namely domestic fans, washing machines, mixer grinders and cooling fan applications. This paper focuses on selecting the best laminating material for the interior permanent magnet brushless DC (IPM BLDC) motor used in the cooling fan of automobiles. Various laminating materials, namely M19-29GA, M800-65A and M43, are tested using finite element analysis. The machine's vital performance metrics, namely the stator current, torque ripple, and hysteresis loss were analyzed in selecting the laminating material. The designed motor is also modelled as a mathematical model from the computed lumped parameters. The performance of the machines was validated through electromagnetic and thermal analysis.
{"title":"Investigation of Various Laminating Materials for Interior Permanent Magnet Brushless DC Motor for Cooling Fan Application","authors":"A. Infantraj;M. Augustine;E. Fantin Irudaya Raj;M. Appadurai","doi":"10.30941/CESTEMS.2023.00048","DOIUrl":"https://doi.org/10.30941/CESTEMS.2023.00048","url":null,"abstract":"Permanent magnet brushless DC motors are used for various low-power applications, namely domestic fans, washing machines, mixer grinders and cooling fan applications. This paper focuses on selecting the best laminating material for the interior permanent magnet brushless DC (IPM BLDC) motor used in the cooling fan of automobiles. Various laminating materials, namely M19-29GA, M800-65A and M43, are tested using finite element analysis. The machine's vital performance metrics, namely the stator current, torque ripple, and hysteresis loss were analyzed in selecting the laminating material. The designed motor is also modelled as a mathematical model from the computed lumped parameters. The performance of the machines was validated through electromagnetic and thermal analysis.","PeriodicalId":100229,"journal":{"name":"CES Transactions on Electrical Machines and Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10375946","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139060228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Content","authors":"","doi":"","DOIUrl":"https://doi.org/","url":null,"abstract":"","PeriodicalId":100229,"journal":{"name":"CES Transactions on Electrical Machines and Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10375945","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139060261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Content","authors":"","doi":"","DOIUrl":"https://doi.org/","url":null,"abstract":"","PeriodicalId":100229,"journal":{"name":"CES Transactions on Electrical Machines and Systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/7873789/10272303/10272305.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68150014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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