As the IT sector is rapidly growing all over the world, more and more energy is consumed by data centers, which leads to the continuous increase of operating costs. Among other factors, the load management among uninterruptible power supply (UPS) nodes should be considered in the energy management model of data center since its energy efficiency is correlated to load ratio. In this paper, an energy management scheme of data center which focuses on the workload scheduling among UPS nodes is proposed to improve its operation efficiency. The flexible service requirement of batch workloads is also modeled in the proposed scheme to illustrate the cost of flexibility. In the proposed scheme, the efficiency of UPS nodes is modeled as a function of load ratio. Meanwhile, the cost of inconvenience is introduced to represent the flexible service requirements of batch workloads. A stochastic formulation is established to address the uncertainties involved in the scheduling process. Simulated case studies are provided and the results demonstrate the effectiveness of this proposed approach.
{"title":"UPS Node based Workload Management for Data Centers considering Flexible Service Requirements","authors":"Fang Cao, Yajing Wang, Fengtian Zhu, Yujie Cao, Zhaohao Ding","doi":"10.1109/ICPS.2019.8733361","DOIUrl":"https://doi.org/10.1109/ICPS.2019.8733361","url":null,"abstract":"As the IT sector is rapidly growing all over the world, more and more energy is consumed by data centers, which leads to the continuous increase of operating costs. Among other factors, the load management among uninterruptible power supply (UPS) nodes should be considered in the energy management model of data center since its energy efficiency is correlated to load ratio. In this paper, an energy management scheme of data center which focuses on the workload scheduling among UPS nodes is proposed to improve its operation efficiency. The flexible service requirement of batch workloads is also modeled in the proposed scheme to illustrate the cost of flexibility. In the proposed scheme, the efficiency of UPS nodes is modeled as a function of load ratio. Meanwhile, the cost of inconvenience is introduced to represent the flexible service requirements of batch workloads. A stochastic formulation is established to address the uncertainties involved in the scheduling process. Simulated case studies are provided and the results demonstrate the effectiveness of this proposed approach.","PeriodicalId":160476,"journal":{"name":"2019 IEEE/IAS 55th Industrial and Commercial Power Systems Technical Conference (I&CPS)","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130742148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-05-01DOI: 10.1109/ICPS.2019.8733334
K. Subramaniam, M. Illindala
Faults in dc microgrids require quick interruption than in traditional ac power systems. This is due to the reduced stiffness of dc microgrids being powered by low inertia DERs interfaced to through power converters. For a high impedance fault, the limited magnitude of the fault current poses additional challenges in identification and locating the faults in the system, with difficulty in distinguishing the fault condition from the normal operating condition. This paper focuses on designing a cost-effective protection system for fast identification, selective isolation of high impedance faults and system restoration in such dc microgrids through proper coordination of source converters with sectionalizers, and with no solid state circuit breakers in action. The high impedance faults are identified through multi resolution analysis of the locally measured current signals with discrete wavelet transform and K-nearest neighbor based classifier at each source converter and contactor. The selectivity is achieved through adaptive resistance time curves set by the controllers installed at each contactor in the system.
{"title":"High Impedance Fault Detection and Isolation in DC Microgrids","authors":"K. Subramaniam, M. Illindala","doi":"10.1109/ICPS.2019.8733334","DOIUrl":"https://doi.org/10.1109/ICPS.2019.8733334","url":null,"abstract":"Faults in dc microgrids require quick interruption than in traditional ac power systems. This is due to the reduced stiffness of dc microgrids being powered by low inertia DERs interfaced to through power converters. For a high impedance fault, the limited magnitude of the fault current poses additional challenges in identification and locating the faults in the system, with difficulty in distinguishing the fault condition from the normal operating condition. This paper focuses on designing a cost-effective protection system for fast identification, selective isolation of high impedance faults and system restoration in such dc microgrids through proper coordination of source converters with sectionalizers, and with no solid state circuit breakers in action. The high impedance faults are identified through multi resolution analysis of the locally measured current signals with discrete wavelet transform and K-nearest neighbor based classifier at each source converter and contactor. The selectivity is achieved through adaptive resistance time curves set by the controllers installed at each contactor in the system.","PeriodicalId":160476,"journal":{"name":"2019 IEEE/IAS 55th Industrial and Commercial Power Systems Technical Conference (I&CPS)","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130832938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-05-01DOI: 10.1109/ICPS.2019.8733338
Ching-Jin Chen, C. Su, J. Teng
Electric load analysis is an important task in early new stage for design of shipboard microgrids (SMGs). The installation generation capacity onboard depends on the accurate result of the analysis, which significantly affects the system economic and secure operations. In the traditional electrical load analysis, the demand factor is often obtained from engineering experiences which can lead to inaccurate analysis results. In order to obtain better results, a methodology for electrical load analysis in SMGs is proposed in this paper. The load analysis spreadsheet is adopted to find the power consumption of key electric loads in SMGs. The actual power consumption of selected loads are collected by intelligent meters. The statistical analysis is then performed to find the critical parameter of each selected load in the load analysis under different operating conditions based on the power measurement of field test and load analysis is performed for estimating system power demand accordingly. Three large practical maritime microgrids are selected for numerical analysis to ensure the performance of proposed method. The proposed method has been adopted by local ship builders in Taiwan to better understand the load characteristics in shipboard microgrids to support various functions of system planning and operation in a more effective manner.
{"title":"Determination of Load Characteristics for Electrical Load Analysis in Shipboard Microgrids","authors":"Ching-Jin Chen, C. Su, J. Teng","doi":"10.1109/ICPS.2019.8733338","DOIUrl":"https://doi.org/10.1109/ICPS.2019.8733338","url":null,"abstract":"Electric load analysis is an important task in early new stage for design of shipboard microgrids (SMGs). The installation generation capacity onboard depends on the accurate result of the analysis, which significantly affects the system economic and secure operations. In the traditional electrical load analysis, the demand factor is often obtained from engineering experiences which can lead to inaccurate analysis results. In order to obtain better results, a methodology for electrical load analysis in SMGs is proposed in this paper. The load analysis spreadsheet is adopted to find the power consumption of key electric loads in SMGs. The actual power consumption of selected loads are collected by intelligent meters. The statistical analysis is then performed to find the critical parameter of each selected load in the load analysis under different operating conditions based on the power measurement of field test and load analysis is performed for estimating system power demand accordingly. Three large practical maritime microgrids are selected for numerical analysis to ensure the performance of proposed method. The proposed method has been adopted by local ship builders in Taiwan to better understand the load characteristics in shipboard microgrids to support various functions of system planning and operation in a more effective manner.","PeriodicalId":160476,"journal":{"name":"2019 IEEE/IAS 55th Industrial and Commercial Power Systems Technical Conference (I&CPS)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132975942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-05-01DOI: 10.1109/ICPS.2019.8733341
T. Patcharoen, A. Ngaopitakkul
An unbalance current protection relay (60C, 51NC) cannot operate fast enough to avoid catastrophic failure against high system fault currents within capacitor units because traditional unbalance current protection relays are not capable of distinguishing and classifying transient fault current and switching inrush current. This paper proposes a new algorithm for the detection and classification of such current signals. The program used for the simulation was PSCAD/EMTDC. The current signals output was used as discrete wavelet transform (DWT) input. The wavelet-based fault and inrush current detection and classification unit received the various captured transient current signals, and used DWT to detect and analyse various cases studies. The actual inrush current signals from both the experimental setup and testing on an actual 115 kV HV shunt capacitor bank were used to verify the proposed algorithm. Results show that the proposed algorithm is effective at accurately identifying fault and inrush currents.
{"title":"Discrete Wavelet Transform for Improving the Accuracy of an Unbalance Current Protection Relay Due to Transient Fault and Inrush Current Signals","authors":"T. Patcharoen, A. Ngaopitakkul","doi":"10.1109/ICPS.2019.8733341","DOIUrl":"https://doi.org/10.1109/ICPS.2019.8733341","url":null,"abstract":"An unbalance current protection relay (60C, 51NC) cannot operate fast enough to avoid catastrophic failure against high system fault currents within capacitor units because traditional unbalance current protection relays are not capable of distinguishing and classifying transient fault current and switching inrush current. This paper proposes a new algorithm for the detection and classification of such current signals. The program used for the simulation was PSCAD/EMTDC. The current signals output was used as discrete wavelet transform (DWT) input. The wavelet-based fault and inrush current detection and classification unit received the various captured transient current signals, and used DWT to detect and analyse various cases studies. The actual inrush current signals from both the experimental setup and testing on an actual 115 kV HV shunt capacitor bank were used to verify the proposed algorithm. Results show that the proposed algorithm is effective at accurately identifying fault and inrush currents.","PeriodicalId":160476,"journal":{"name":"2019 IEEE/IAS 55th Industrial and Commercial Power Systems Technical Conference (I&CPS)","volume":"292 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117329131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-05-01DOI: 10.1109/ICPS.2019.8733348
Long Zhao, I. Matsuo, Yuhao Zhou, Weijen Lee
The Internet of Things (IoT) concept allows objects to share data through wired or wireless connections for communication purposes. The Industrial Internet of Things (IIoT) is an extended concept of IoT that refers to an integration of data acquisition, communication, and processing on a real-time network. Currently, IIoT has been involved with the development of smart grids in many applications. As the operation of power systems is extremely time-critical, low-latency communication needs to be considered for most control and monitoring applications. Real-time capability of IoT is considered as a key feature for monitoring and control applications of power systems. Therefore, system operators can use the real-time monitoring system to provide better decisions for both technical and financial-related matters. In this paper, a high-speed IIoT-based monitoring system with recording functions is developed and implemented for a power system substation. Due to the high reliability and processing speed of FPGAs, an FPGA-embedded controller is adopted in this system. The IoT platform also provides remote visualization for system operators in real time. This paper mainly aims to provide a practical application that was implemented and tested in a real power substation. The system incorporates the features of an IoT platform with the needs of high-speed real-time applications while using a single high-resolution time source as the reference for both steady-state and transient conditions.
{"title":"Design of an Industrial IoT-Based Monitoring System for Power Substations","authors":"Long Zhao, I. Matsuo, Yuhao Zhou, Weijen Lee","doi":"10.1109/ICPS.2019.8733348","DOIUrl":"https://doi.org/10.1109/ICPS.2019.8733348","url":null,"abstract":"The Internet of Things (IoT) concept allows objects to share data through wired or wireless connections for communication purposes. The Industrial Internet of Things (IIoT) is an extended concept of IoT that refers to an integration of data acquisition, communication, and processing on a real-time network. Currently, IIoT has been involved with the development of smart grids in many applications. As the operation of power systems is extremely time-critical, low-latency communication needs to be considered for most control and monitoring applications. Real-time capability of IoT is considered as a key feature for monitoring and control applications of power systems. Therefore, system operators can use the real-time monitoring system to provide better decisions for both technical and financial-related matters. In this paper, a high-speed IIoT-based monitoring system with recording functions is developed and implemented for a power system substation. Due to the high reliability and processing speed of FPGAs, an FPGA-embedded controller is adopted in this system. The IoT platform also provides remote visualization for system operators in real time. This paper mainly aims to provide a practical application that was implemented and tested in a real power substation. The system incorporates the features of an IoT platform with the needs of high-speed real-time applications while using a single high-resolution time source as the reference for both steady-state and transient conditions.","PeriodicalId":160476,"journal":{"name":"2019 IEEE/IAS 55th Industrial and Commercial Power Systems Technical Conference (I&CPS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124848432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-05-01DOI: 10.1109/ICPS.2019.8733342
C. Bates, Pk Sen
A cable ampacity study for a PV power plant is evaluated based on temperature measurements taken during normal operation for one year. Differences between the design and the installation are discussed regarding their impact on cable temperature. Soil thermal resistivity measurements are reviewed, highlighting the need for the design engineer to properly specify the soil conditions for the measurement. The measured temperature was significantly less than the temperature calculated using the Neher-McGrath method.
{"title":"Solar PV Power Plant Underground Cable Sizing Case Study","authors":"C. Bates, Pk Sen","doi":"10.1109/ICPS.2019.8733342","DOIUrl":"https://doi.org/10.1109/ICPS.2019.8733342","url":null,"abstract":"A cable ampacity study for a PV power plant is evaluated based on temperature measurements taken during normal operation for one year. Differences between the design and the installation are discussed regarding their impact on cable temperature. Soil thermal resistivity measurements are reviewed, highlighting the need for the design engineer to properly specify the soil conditions for the measurement. The measured temperature was significantly less than the temperature calculated using the Neher-McGrath method.","PeriodicalId":160476,"journal":{"name":"2019 IEEE/IAS 55th Industrial and Commercial Power Systems Technical Conference (I&CPS)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123179067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-05-01DOI: 10.1109/ICPS.2019.8733381
Suntiti Yoomak, A. Ngaopitakkul
This study investigates and analyses the feasibility of different energy storage systems for solar road lighting systems. The energy storage systems used in this study are divided into two cases, namely homogenous energy storage system (lead-acid (LA) batteries, lithium-ion (LI) batteries, and ultracapacitors (UCs)) and hybrid energy storage systems (leadacid batteries with ultracapacitors (LA and UC) and lithium-ion batteries with ultracapacitors (LI and UC)). Various solar power schemes are implemented based on stable and unstable solar irradiance conditions using an experimental setup. Economic analysis of the solar road lighting systems is performed based on the presented energy storage systems using discounted payback period (DPP), net present value (NPV), and internal rate of return (IRR). The installation of energy storage systems with individual and central systems for the solar road lighting system is also discussed. Results show that LA batteries, LI batteries, and UCs yielded satisfactory active power quality for effective charging in all ranges of solar irradiance. However, the lifetimes of battery devices are degraded during dynamic active power charging. To overcome this shortcoming, hybrid energy storage systems are proposed using batteries and UCs. The use of LA batteries yields the lowest installation cost. However, LI batteries offer the best economic viability in the long term. The cost of UCs is too high to be used as an energy storage system for solar road lighting systems. However, the use of appropriate proportions of UCs with batteries to reduce current and active power fluctuations for charging the batteries is economically viable.
{"title":"Feasibility Analysis of Different Energy Storage Systems for Solar Road Lighting Systems","authors":"Suntiti Yoomak, A. Ngaopitakkul","doi":"10.1109/ICPS.2019.8733381","DOIUrl":"https://doi.org/10.1109/ICPS.2019.8733381","url":null,"abstract":"This study investigates and analyses the feasibility of different energy storage systems for solar road lighting systems. The energy storage systems used in this study are divided into two cases, namely homogenous energy storage system (lead-acid (LA) batteries, lithium-ion (LI) batteries, and ultracapacitors (UCs)) and hybrid energy storage systems (leadacid batteries with ultracapacitors (LA and UC) and lithium-ion batteries with ultracapacitors (LI and UC)). Various solar power schemes are implemented based on stable and unstable solar irradiance conditions using an experimental setup. Economic analysis of the solar road lighting systems is performed based on the presented energy storage systems using discounted payback period (DPP), net present value (NPV), and internal rate of return (IRR). The installation of energy storage systems with individual and central systems for the solar road lighting system is also discussed. Results show that LA batteries, LI batteries, and UCs yielded satisfactory active power quality for effective charging in all ranges of solar irradiance. However, the lifetimes of battery devices are degraded during dynamic active power charging. To overcome this shortcoming, hybrid energy storage systems are proposed using batteries and UCs. The use of LA batteries yields the lowest installation cost. However, LI batteries offer the best economic viability in the long term. The cost of UCs is too high to be used as an energy storage system for solar road lighting systems. However, the use of appropriate proportions of UCs with batteries to reduce current and active power fluctuations for charging the batteries is economically viable.","PeriodicalId":160476,"journal":{"name":"2019 IEEE/IAS 55th Industrial and Commercial Power Systems Technical Conference (I&CPS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130323951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-05-01DOI: 10.1109/ICPS.2019.8733339
Zhe Li, Hongcai Chen, Yi Wu, Ya-ping Du, Yang Zhang
This paper analyzes the lightning transients in a commercial building with a grid like structure. The simulation is performed by using the Partial Element Equivalent Circuit (PEEC) method. Both the skin effect of the conductors and the nonlinear protection devices are taken into consideration. The current distribution in the structure, the induced voltage in the wiring system with different SPDs installations and the current sharing in the wiring system are discussed. Finally, suggestions are provided for effective protection against lightning in buildings.
{"title":"Analysis of Lightning Transients in a Commercial Building Using the PEEC Method","authors":"Zhe Li, Hongcai Chen, Yi Wu, Ya-ping Du, Yang Zhang","doi":"10.1109/ICPS.2019.8733339","DOIUrl":"https://doi.org/10.1109/ICPS.2019.8733339","url":null,"abstract":"This paper analyzes the lightning transients in a commercial building with a grid like structure. The simulation is performed by using the Partial Element Equivalent Circuit (PEEC) method. Both the skin effect of the conductors and the nonlinear protection devices are taken into consideration. The current distribution in the structure, the induced voltage in the wiring system with different SPDs installations and the current sharing in the wiring system are discussed. Finally, suggestions are provided for effective protection against lightning in buildings.","PeriodicalId":160476,"journal":{"name":"2019 IEEE/IAS 55th Industrial and Commercial Power Systems Technical Conference (I&CPS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126288067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-05-01DOI: 10.1109/ICPS.2019.8733369
Massimo Mitolo, M. Tartaglia, G. Zizzo
The resonant grounding is one of the possible methods of system neutral grounding for the medium-voltage distribution. IEEE standards do define this grounding configuration, but important advantages and drawbacks of the resonant grounding might not be fully known, due to its rather uncommon application in North America. On the other hand, resonant grounding in Europe is imposed by the increased requirements for power quality, especially for medium-voltage industrial users, and imposed to electric utilities by Regulatory Authorities, with the purpose to protect the interests of users and consumers. Level of the continuity of the service, magnitude and phase of ground-fault currents, magnitude of touch voltages, all depend on how the neutral is connected to ground. In this paper, the authors will discuss electrical safety features of the resonant ground, and analyze issues when a substation, originally operated with different methods of system neutral grounding, is reconfigured with a resonant ground.
{"title":"Electrical Safety of Resonant Grounding","authors":"Massimo Mitolo, M. Tartaglia, G. Zizzo","doi":"10.1109/ICPS.2019.8733369","DOIUrl":"https://doi.org/10.1109/ICPS.2019.8733369","url":null,"abstract":"The resonant grounding is one of the possible methods of system neutral grounding for the medium-voltage distribution. IEEE standards do define this grounding configuration, but important advantages and drawbacks of the resonant grounding might not be fully known, due to its rather uncommon application in North America. On the other hand, resonant grounding in Europe is imposed by the increased requirements for power quality, especially for medium-voltage industrial users, and imposed to electric utilities by Regulatory Authorities, with the purpose to protect the interests of users and consumers. Level of the continuity of the service, magnitude and phase of ground-fault currents, magnitude of touch voltages, all depend on how the neutral is connected to ground. In this paper, the authors will discuss electrical safety features of the resonant ground, and analyze issues when a substation, originally operated with different methods of system neutral grounding, is reconfigured with a resonant ground.","PeriodicalId":160476,"journal":{"name":"2019 IEEE/IAS 55th Industrial and Commercial Power Systems Technical Conference (I&CPS)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125265467","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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