Pub Date : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980519
Rómulo Antão, A. Mota, Rui Escadas Martins
The capability of dealing with unpredictable variations of a process under manipulation is one of the most sought features when implementing digital control loops. Self tuning regulators are one type of control systems with such capability, existing several successful application of it in industry. However implementations of such systems are typically based on computationally intensive algorithms that, when applied to processes with fast dynamics, require high performance but complex and expensive embedded systems to cope with the required control-loop turnaround times. With the performance improvements brought by the new ARM Cortex M4, general purpose microcontrollers and advanced digital signal processing are no longer disjoint domains, becoming now possible to develop more versatile and robust control algorithms on affordable embedded systems with less restrictive computational limitations. Taking advantage of this architecture, this paper will present a real-time embedded adaptive controller applied to a Buck DC-DC converter. To assess the capabilities of this new architecture, comparative measurements of the algorithm's CPU usage under different system configurations and results relative to the setpoint tracking capability of the adaptive controller under time-varying dynamics will be presented.
{"title":"Adaptive control of a buck converter with an ARM Cortex-M4","authors":"Rómulo Antão, A. Mota, Rui Escadas Martins","doi":"10.1109/EPEPEMC.2014.6980519","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980519","url":null,"abstract":"The capability of dealing with unpredictable variations of a process under manipulation is one of the most sought features when implementing digital control loops. Self tuning regulators are one type of control systems with such capability, existing several successful application of it in industry. However implementations of such systems are typically based on computationally intensive algorithms that, when applied to processes with fast dynamics, require high performance but complex and expensive embedded systems to cope with the required control-loop turnaround times. With the performance improvements brought by the new ARM Cortex M4, general purpose microcontrollers and advanced digital signal processing are no longer disjoint domains, becoming now possible to develop more versatile and robust control algorithms on affordable embedded systems with less restrictive computational limitations. Taking advantage of this architecture, this paper will present a real-time embedded adaptive controller applied to a Buck DC-DC converter. To assess the capabilities of this new architecture, comparative measurements of the algorithm's CPU usage under different system configurations and results relative to the setpoint tracking capability of the adaptive controller under time-varying dynamics will be presented.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"154 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123528418","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980632
M. Işık, M. Haboglu, Hilmi Yanmaz
The control of mechanical systems are generally applied by using electric motors which are useful for the control of velocity, position and torque. On the other hand, servo motors are preferred due to their characteristic properties for the systems that require more accurate operations. In this study, a mechanical prototype having a two degree of freedom motion capacity integrated with AC servo motors is generated. The control of those AC servo motors is achieved by using an Omron PLC (Programmable Logic Controller). A SCADA program is developed for user control and monitoring. The connection between SCADA and PLC is obtained by using Device-Net web protocol. The velocity and position of the motion control system are monitored with real time animation on the screen. It is observed after the testing of the designed system that the position and velocity values are convenient.
{"title":"Monitoring and control of PLC based motion control systems via device-net","authors":"M. Işık, M. Haboglu, Hilmi Yanmaz","doi":"10.1109/EPEPEMC.2014.6980632","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980632","url":null,"abstract":"The control of mechanical systems are generally applied by using electric motors which are useful for the control of velocity, position and torque. On the other hand, servo motors are preferred due to their characteristic properties for the systems that require more accurate operations. In this study, a mechanical prototype having a two degree of freedom motion capacity integrated with AC servo motors is generated. The control of those AC servo motors is achieved by using an Omron PLC (Programmable Logic Controller). A SCADA program is developed for user control and monitoring. The connection between SCADA and PLC is obtained by using Device-Net web protocol. The velocity and position of the motion control system are monitored with real time animation on the screen. It is observed after the testing of the designed system that the position and velocity values are convenient.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"269 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121138668","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}
Aircraft technology is moving toward what is known as More Electric Aircraft. This technology aims to increase the amount of electrical power equipments rather than mechanical or hydraulic equipments. This paper present an analytical method of calculating reactive and harmonic current and using this current as a reference to feed a series active filter to compensate the harmonic currents generated by a non linear load.
{"title":"Single phase series active filter load compensation for aircraft applications","authors":"M. Taha","doi":"10.19072/ijet.04696","DOIUrl":"https://doi.org/10.19072/ijet.04696","url":null,"abstract":"Aircraft technology is moving toward what is known as More Electric Aircraft. This technology aims to increase the amount of electrical power equipments rather than mechanical or hydraulic equipments. This paper present an analytical method of calculating reactive and harmonic current and using this current as a reference to feed a series active filter to compensate the harmonic currents generated by a non linear load.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"2018 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121276151","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980538
M. Seilmeier, B. Piepenbreier
This paper presents an initial start-up and magnet polarity estimation method for PMSM using the alternating HF test current injection based sensorless control scheme for low speed range and evaluation of the saturation dependent HF d-axis inductance. The proposed magnet polarity estimation method consists of two steps: The first step is to activate the HF injection based sensorless current control scheme providing either the orientation of the d or -d-axis. To eliminate the ambiguity of the result from the first step, the magnet polarity information is obtained in the second step by exciting the estimated d-axis with a DC current. The magnet polarity can be detected by evaluation of whether the d-axis inductance increases or decreases due to saturation. Initial position estimation errors which can occur due to secondary saliencies can be compensated for easily by use of the flatness based test signal pre-control which is used for the test current injection based sensorless control anyway. Experimental results show proper functioning of the proposed method.
{"title":"Initial start-up and magnet polarity estimation method for HF test current injection based sensorless control of PMSM","authors":"M. Seilmeier, B. Piepenbreier","doi":"10.1109/EPEPEMC.2014.6980538","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980538","url":null,"abstract":"This paper presents an initial start-up and magnet polarity estimation method for PMSM using the alternating HF test current injection based sensorless control scheme for low speed range and evaluation of the saturation dependent HF d-axis inductance. The proposed magnet polarity estimation method consists of two steps: The first step is to activate the HF injection based sensorless current control scheme providing either the orientation of the d or -d-axis. To eliminate the ambiguity of the result from the first step, the magnet polarity information is obtained in the second step by exciting the estimated d-axis with a DC current. The magnet polarity can be detected by evaluation of whether the d-axis inductance increases or decreases due to saturation. Initial position estimation errors which can occur due to secondary saliencies can be compensated for easily by use of the flatness based test signal pre-control which is used for the test current injection based sensorless control anyway. Experimental results show proper functioning of the proposed method.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127684638","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980552
J. Itoh, H. D. Minh, D. Sato
This paper discusses the conduction noise reduction possibility of a transformer-less three-level V-connection rectifier-inverter system. This circuit is used for the main circuit in an Uninterruptible Power Supply (UPS) system. The efficiency of this circuit is higher than that of the conventional three-phase rectifier-inverter circuit due to no isolated transformer in output side. In this paper, to verify the conduction noise of the V-connection system, a theoretical analysis about the common-mode currents which based on the common-mode equivalent circuit, is discussed. Based on this, the comparison of the conduction noise between the three-level V-connection Back To Back (BTB) system and the conventional three-level three-phase connection BTB system is assumed. In addition, the conduction noise of two systems are measured and compared in order to confirm the assumption. As a result, it is confirmed that the conduction noise which is generated from the three-level V-connection rectifier-inverter circuit is higher than that of the conventional three-phase rectifier-inverter circuit.
本文讨论了一种无变压器的三电平v接整逆变系统降低传导噪声的可能性。该电路用于UPS (uninterrupted Power Supply)系统的主电路。由于输出侧无隔离变压器，该电路的效率高于传统的三相整逆变电路。为了验证v型连接系统的传导噪声，本文基于共模等效电路对共模电流进行了理论分析。在此基础上，对三电平v接背对背(BTB)系统与传统三电平三相接BTB系统的传导噪声进行了比较假设。此外，还对两种系统的传导噪声进行了测量和比较，以验证上述假设。结果证实，三电平v接整流-逆变电路产生的传导噪声高于常规三相整流-逆变电路。
{"title":"Experimental verification of conduction noise of three-level V-connection rectifier-inverter system","authors":"J. Itoh, H. D. Minh, D. Sato","doi":"10.1109/EPEPEMC.2014.6980552","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980552","url":null,"abstract":"This paper discusses the conduction noise reduction possibility of a transformer-less three-level V-connection rectifier-inverter system. This circuit is used for the main circuit in an Uninterruptible Power Supply (UPS) system. The efficiency of this circuit is higher than that of the conventional three-phase rectifier-inverter circuit due to no isolated transformer in output side. In this paper, to verify the conduction noise of the V-connection system, a theoretical analysis about the common-mode currents which based on the common-mode equivalent circuit, is discussed. Based on this, the comparison of the conduction noise between the three-level V-connection Back To Back (BTB) system and the conventional three-level three-phase connection BTB system is assumed. In addition, the conduction noise of two systems are measured and compared in order to confirm the assumption. As a result, it is confirmed that the conduction noise which is generated from the three-level V-connection rectifier-inverter circuit is higher than that of the conventional three-phase rectifier-inverter circuit.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126317384","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980710
Z. Ancik, Z. Hadaš, R. Vlach, L. Janak, V. Singule, P. Procházka
This paper deals with a simulation modelling of a thermoelectric energy harvester for aircraft applications. The aim of this paper is to provide overview of simulation modelling methods, which are used in development process of the autonomic thermoelectric energy harvester. The assumed harvester is based on MEMS technology and is capable to operate as an independent energy source under high range of operational condition required by aircraft applications.
{"title":"Simulation modelling of MEMS thermoelectric generator for aircraft applications","authors":"Z. Ancik, Z. Hadaš, R. Vlach, L. Janak, V. Singule, P. Procházka","doi":"10.1109/EPEPEMC.2014.6980710","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980710","url":null,"abstract":"This paper deals with a simulation modelling of a thermoelectric energy harvester for aircraft applications. The aim of this paper is to provide overview of simulation modelling methods, which are used in development process of the autonomic thermoelectric energy harvester. The assumed harvester is based on MEMS technology and is capable to operate as an independent energy source under high range of operational condition required by aircraft applications.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121944057","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980600
Hiroto Chikaura, Y. Oka, Y. Nakashima, Y. Nakanishi
Ocean current or tidal power is a promising renewable resource. For the generation of electricity from them, it is important to construct waterproof system with reducing mechanical energy loss. However, there is no appropriate sealing system that is completely waterproof and low friction. So, we developed a new type of seal system for using in ocean current and tidal power generation. We introduced seal lips made of a polyvinyl formal (PVF). PVF lips were attached to a rotating shaft, and a non-Newtonian, aqueous solution of 3.0wt% polyethylene glycol (PEG) with a molecular weight of 2.0 million was applied as lubrication. This sealing system was low water leakage, less than 0.05ml/h, was recorded throughout the experiment. Mean frictional torque was lower than those with a mechanical seal or an oil seal, both of which are generally used for industrial components. Furthermore, frictional torque was stable, and friction was independent of the speed of the rotating shaft.
{"title":"Development of a new type of seal system for use in ocean current or tidal power generation","authors":"Hiroto Chikaura, Y. Oka, Y. Nakashima, Y. Nakanishi","doi":"10.1109/EPEPEMC.2014.6980600","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980600","url":null,"abstract":"Ocean current or tidal power is a promising renewable resource. For the generation of electricity from them, it is important to construct waterproof system with reducing mechanical energy loss. However, there is no appropriate sealing system that is completely waterproof and low friction. So, we developed a new type of seal system for using in ocean current and tidal power generation. We introduced seal lips made of a polyvinyl formal (PVF). PVF lips were attached to a rotating shaft, and a non-Newtonian, aqueous solution of 3.0wt% polyethylene glycol (PEG) with a molecular weight of 2.0 million was applied as lubrication. This sealing system was low water leakage, less than 0.05ml/h, was recorded throughout the experiment. Mean frictional torque was lower than those with a mechanical seal or an oil seal, both of which are generally used for industrial components. Furthermore, frictional torque was stable, and friction was independent of the speed of the rotating shaft.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130142206","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980506
W. Wickramasinghe, K. Duleeka, H. D. Kolamunna, S. Abeyratne
This research touches a major problem in automobile industry. Which is that, the engine cranking fails when the battery is drained to a certain depth of discharge, though the battery has enough energy for cranking, due to the dynamic behaviour of the internal resistance upon the state of charge of a lead acid battery. Our work is focused on finding-out the capability of cranking an internal combustion engine using such a battery while utilizing the battery-energy with the use of a power electronics assisted methodology. This paper consists of the study on the requirements of a vehicle engine for a healthy start, the characteristics of a battery at both starting and non-starting conditions, and the power electronic assisted method of compensating the starting requirements of the vehicles' electrical system at a non-starting condition. In that direction, field tests were carried out and the results were analyzed. Finally the proposed electronic assisted vehicle starting method was simulated and proved as a concept to be implemented practically. Here we have used a memory Hicorder to record data in field tests and MATLAB Simulink tool as the simulation workbench.
{"title":"A power electronics assisted emergency vehicle starter","authors":"W. Wickramasinghe, K. Duleeka, H. D. Kolamunna, S. Abeyratne","doi":"10.1109/EPEPEMC.2014.6980506","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980506","url":null,"abstract":"This research touches a major problem in automobile industry. Which is that, the engine cranking fails when the battery is drained to a certain depth of discharge, though the battery has enough energy for cranking, due to the dynamic behaviour of the internal resistance upon the state of charge of a lead acid battery. Our work is focused on finding-out the capability of cranking an internal combustion engine using such a battery while utilizing the battery-energy with the use of a power electronics assisted methodology. This paper consists of the study on the requirements of a vehicle engine for a healthy start, the characteristics of a battery at both starting and non-starting conditions, and the power electronic assisted method of compensating the starting requirements of the vehicles' electrical system at a non-starting condition. In that direction, field tests were carried out and the results were analyzed. Finally the proposed electronic assisted vehicle starting method was simulated and proved as a concept to be implemented practically. Here we have used a memory Hicorder to record data in field tests and MATLAB Simulink tool as the simulation workbench.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127851829","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980635
Hirotaka Takahashi, Noriyoshi Tabata, H. Ikarashi, Kazuharu Honda, Masahiko Ando, Youngik Kim
Technology development has been promoted aiming for an environment-friendly traction power supply system for railways. Among other things, a stationary energy storage system using lithium ion batteries for hybrid cars has been put into practical use since 2007. This device temporarily stores regenerative power generated from an train when it is stopped and the power is able to be applied for energy saving, measures against regeneration canceled and compensation for a voltage drop. The implementation planning for a stationary energy storage system (SESS) has been popular in recent years. The implementation of the SESS at railway companies can contribute to the reduction in the global warming gas emissions.
{"title":"Lithium ion battery application in traction power supply system","authors":"Hirotaka Takahashi, Noriyoshi Tabata, H. Ikarashi, Kazuharu Honda, Masahiko Ando, Youngik Kim","doi":"10.1109/EPEPEMC.2014.6980635","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980635","url":null,"abstract":"Technology development has been promoted aiming for an environment-friendly traction power supply system for railways. Among other things, a stationary energy storage system using lithium ion batteries for hybrid cars has been put into practical use since 2007. This device temporarily stores regenerative power generated from an train when it is stopped and the power is able to be applied for energy saving, measures against regeneration canceled and compensation for a voltage drop. The implementation planning for a stationary energy storage system (SESS) has been popular in recent years. The implementation of the SESS at railway companies can contribute to the reduction in the global warming gas emissions.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124372067","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 : 2014-12-11DOI: 10.1109/EPEPEMC.2014.6980642
S. Valtchev, Rui Neves-Medeiros, A. Krusteva, G. Gigov, P. Avramov
A contactless energy transmitter/receiver set is designed and its electrical parameters are tested varying the working frequency in the kHz range and the transceiver's distance. The goal is to improve the efficiency of the wireless charging of different batteries from the smart grid, guaranteeing more acceptable use of the electric vehicles.
{"title":"A wireless energy transceiver based on induction heating equipment","authors":"S. Valtchev, Rui Neves-Medeiros, A. Krusteva, G. Gigov, P. Avramov","doi":"10.1109/EPEPEMC.2014.6980642","DOIUrl":"https://doi.org/10.1109/EPEPEMC.2014.6980642","url":null,"abstract":"A contactless energy transmitter/receiver set is designed and its electrical parameters are tested varying the working frequency in the kHz range and the transceiver's distance. The goal is to improve the efficiency of the wireless charging of different batteries from the smart grid, guaranteeing more acceptable use of the electric vehicles.","PeriodicalId":325670,"journal":{"name":"2014 16th International Power Electronics and Motion Control Conference and Exposition","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114333089","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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