Pub Date : 2014-11-24DOI: 10.1109/NAPS.2014.6965353
A. Nagarajan, R. Ayyanar
This paper demonstrates the application of a graph search algorithm for the network reduction of the distribution feeder. The purpose behind the network-reduction is to develop a reduced distribution system to facilitate the dynamic analysis of the feeders with high penetration of PV generators. Dynamic analysis requires modeling of the distribution feeders in the electromagnetic transient programs for understanding the transients. Performing the transient analysis on large distribution feeders with high PV penetration is time intensive and impracticable. To aid this purpose a network-reduction algorithm for the distribution feeder is proposed in this paper. The objective is to develop a reduced distribution system to support the study of long-term transients of the PV inverters such as - interaction with other control devices (capacitor banks and PV generators), cloud transients, and voltage flicker. This paper proposes a novel network-reduction technique, based on a network-flow procedure, which is referred to as Minimum Spanning Tree (MST) with additional capabilities. The network reduction proposed in this paper selectively retains the laterals and additionally accommodates the reactive power generation from the cable capacitance to the loads. The proposed algorithm will serve as an interface for modeling the feeder from the GIS database to the transient analysis tool.
{"title":"Application of Minimum Spanning Tree algorithm for network reduction of distribution systems","authors":"A. Nagarajan, R. Ayyanar","doi":"10.1109/NAPS.2014.6965353","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965353","url":null,"abstract":"This paper demonstrates the application of a graph search algorithm for the network reduction of the distribution feeder. The purpose behind the network-reduction is to develop a reduced distribution system to facilitate the dynamic analysis of the feeders with high penetration of PV generators. Dynamic analysis requires modeling of the distribution feeders in the electromagnetic transient programs for understanding the transients. Performing the transient analysis on large distribution feeders with high PV penetration is time intensive and impracticable. To aid this purpose a network-reduction algorithm for the distribution feeder is proposed in this paper. The objective is to develop a reduced distribution system to support the study of long-term transients of the PV inverters such as - interaction with other control devices (capacitor banks and PV generators), cloud transients, and voltage flicker. This paper proposes a novel network-reduction technique, based on a network-flow procedure, which is referred to as Minimum Spanning Tree (MST) with additional capabilities. The network reduction proposed in this paper selectively retains the laterals and additionally accommodates the reactive power generation from the cable capacitance to the loads. The proposed algorithm will serve as an interface for modeling the feeder from the GIS database to the transient analysis tool.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125541495","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965403
Shamina Hossain, Hao Zhu, T. Overbye
The detection and location of high impedance faults has historically been a difficult endeavor due to the low currents produced. However, the recent advent of distributed voltage monitoring devices, enabling access to fast-sampled, expansive voltage measurements throughout a distribution network, can ease this task. This paper considers the potential to use these distribution level devices to detect and locate such faults. A simulation-based method is proposed that compares a measured voltage profile, obtained from the devices, and simulated voltage profiles at various locations using a power system simulation software. The simulation locations are intelligently selected using the Golden section search and possible fault impedance values are iterated through for each location. The L1-norm is used to compare the two profiles, with the lowest error norm representing the best match - the most likely fault location and impedance.
{"title":"Distribution high impedance fault location using localized voltage magnitude measurements","authors":"Shamina Hossain, Hao Zhu, T. Overbye","doi":"10.1109/NAPS.2014.6965403","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965403","url":null,"abstract":"The detection and location of high impedance faults has historically been a difficult endeavor due to the low currents produced. However, the recent advent of distributed voltage monitoring devices, enabling access to fast-sampled, expansive voltage measurements throughout a distribution network, can ease this task. This paper considers the potential to use these distribution level devices to detect and locate such faults. A simulation-based method is proposed that compares a measured voltage profile, obtained from the devices, and simulated voltage profiles at various locations using a power system simulation software. The simulation locations are intelligently selected using the Golden section search and possible fault impedance values are iterated through for each location. The L1-norm is used to compare the two profiles, with the lowest error norm representing the best match - the most likely fault location and impedance.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"506 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130019072","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965372
Titiksha Joshi, G. Heydt, R. Ayyanar
A project on high penetration of solar photovoltaic resources in a power distribution system is described. The photovoltaic resources energize pulse width modulated inverters to interface with the 60 Hz distribution system. The inverter currents have high frequency components (these are not `harmonics', but they are artifacts of the pulse width modulation and generally they are in the 2.0 kHz range and higher). Residential (i.e., `roof top') PV resources are generally relegated to the 5 kW range or less, while `utility scale' PV in the range of 400 kW or more has been used. Modeling of the distribution feeder appropriate for high frequency studies is discussed and simulation results from high frequency power flow are presented. The distribution system is an actual system in the Western United States, and instrumented measurements are available.
{"title":"High frequency spectral components in distribution voltages and currents due to photovoltaic resources","authors":"Titiksha Joshi, G. Heydt, R. Ayyanar","doi":"10.1109/NAPS.2014.6965372","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965372","url":null,"abstract":"A project on high penetration of solar photovoltaic resources in a power distribution system is described. The photovoltaic resources energize pulse width modulated inverters to interface with the 60 Hz distribution system. The inverter currents have high frequency components (these are not `harmonics', but they are artifacts of the pulse width modulation and generally they are in the 2.0 kHz range and higher). Residential (i.e., `roof top') PV resources are generally relegated to the 5 kW range or less, while `utility scale' PV in the range of 400 kW or more has been used. Modeling of the distribution feeder appropriate for high frequency studies is discussed and simulation results from high frequency power flow are presented. The distribution system is an actual system in the Western United States, and instrumented measurements are available.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115805260","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965388
Hung-Ming Chou, K. Butler-Purry
Because of the slow expansion of distribution systems, fast growth of load, and increased penetration level of distribution generation (DG), voltage stability becomes an important issue for the proper operation of distribution systems. In this work modal analysis technique was extended to three-phase unbalanced distribution systems to analyze voltage stability problem. Netwon-Raphson algorithm with power mismatch in polar representation was adopted to find the three-phase power flow solution, and its Jacobian matrix was used for three-phase modal analysis technique. This technique was applied to IEEE 13-node test feeder. Several case studies were performed to investigate the impact of unbalance loading degree and DG power output on voltage stability problem. It was found that both would influence not only the maximum loadability of the system but also the location of the weak buses, weak branches and suitable locations to provide reactive power support.
{"title":"Investigation of voltage stability in three-phase unbalanced distribution systems with DG using modal analysis technique","authors":"Hung-Ming Chou, K. Butler-Purry","doi":"10.1109/NAPS.2014.6965388","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965388","url":null,"abstract":"Because of the slow expansion of distribution systems, fast growth of load, and increased penetration level of distribution generation (DG), voltage stability becomes an important issue for the proper operation of distribution systems. In this work modal analysis technique was extended to three-phase unbalanced distribution systems to analyze voltage stability problem. Netwon-Raphson algorithm with power mismatch in polar representation was adopted to find the three-phase power flow solution, and its Jacobian matrix was used for three-phase modal analysis technique. This technique was applied to IEEE 13-node test feeder. Several case studies were performed to investigate the impact of unbalance loading degree and DG power output on voltage stability problem. It was found that both would influence not only the maximum loadability of the system but also the location of the weak buses, weak branches and suitable locations to provide reactive power support.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114071412","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965415
A. Esmaeilian, M. Kezunovic
Several major blackouts were caused by distance relay mis-operation. Distance relay mis-operation may occur following a large disturbance in the system causing power swing and out-of-step conditions. If an on-line fault analysis tool is able to detect power swing or out-of-step conditions and indicate mis-operation of relays, the operator may be notified to switch back the healthy transmission lines tripped due to relay mis-operation. A new automated fault analysis tool comprising fault detection, classification and location has been developed and its performance under various power swing and out-of-step conditions is reported. The test results indicate that the fault analysis tool performs better than distance relay under power swing and out of-step conditions and can be used as a tool to verify distance relay operation in practical circumstances. The simulations have been performed using IEEE118 bus test system modeled in ATP software.
{"title":"Evaluation of fault analysis tool under power swing and out-of-step conditions","authors":"A. Esmaeilian, M. Kezunovic","doi":"10.1109/NAPS.2014.6965415","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965415","url":null,"abstract":"Several major blackouts were caused by distance relay mis-operation. Distance relay mis-operation may occur following a large disturbance in the system causing power swing and out-of-step conditions. If an on-line fault analysis tool is able to detect power swing or out-of-step conditions and indicate mis-operation of relays, the operator may be notified to switch back the healthy transmission lines tripped due to relay mis-operation. A new automated fault analysis tool comprising fault detection, classification and location has been developed and its performance under various power swing and out-of-step conditions is reported. The test results indicate that the fault analysis tool performs better than distance relay under power swing and out of-step conditions and can be used as a tool to verify distance relay operation in practical circumstances. The simulations have been performed using IEEE118 bus test system modeled in ATP software.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125781073","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965395
Byungkwon Park, C. DeMarco
This paper revisits active and reactive power decomposition techniques as applied to the optimal power flow problem. The full nonlinear AC optimal power flow problem is decoupled into two lower dimensional nonlinear subproblems (active and reactive), seeking to characterize and exploit the well recognized property of the power flow Jacobian matrix: that the off-diagonal submatrix blocks are in some sense “small,” reflecting the fact that network flow of active power is relatively weakly dependent on bus voltage magnitudes, while reactive power flow is relatively weakly dependent on bus voltage phase angles. We further exploit the fact that the standard objective function of the optimal power flow depends directly on active powers (of generators) only, and different, loss-related objective functions may be used for the reactive subproblem. These formulations are examined in a number of numerical examples, evaluating speed of convergence, and how close decoupled P-Q OPF solution is to that of the full AC OPF. While the improvements in computation time are modest, use of decoupled solutions as initial guesses to a full AC OPF is shown to be promising. In addition to the solution algorithms themselves, a method to characterize the magnitude of off-diagonal coupling terms in the power flow Jacobian is examined.
{"title":"Active/reactive power decomposition approaches to the AC optimal power flow problem","authors":"Byungkwon Park, C. DeMarco","doi":"10.1109/NAPS.2014.6965395","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965395","url":null,"abstract":"This paper revisits active and reactive power decomposition techniques as applied to the optimal power flow problem. The full nonlinear AC optimal power flow problem is decoupled into two lower dimensional nonlinear subproblems (active and reactive), seeking to characterize and exploit the well recognized property of the power flow Jacobian matrix: that the off-diagonal submatrix blocks are in some sense “small,” reflecting the fact that network flow of active power is relatively weakly dependent on bus voltage magnitudes, while reactive power flow is relatively weakly dependent on bus voltage phase angles. We further exploit the fact that the standard objective function of the optimal power flow depends directly on active powers (of generators) only, and different, loss-related objective functions may be used for the reactive subproblem. These formulations are examined in a number of numerical examples, evaluating speed of convergence, and how close decoupled P-Q OPF solution is to that of the full AC OPF. While the improvements in computation time are modest, use of decoupled solutions as initial guesses to a full AC OPF is shown to be promising. In addition to the solution algorithms themselves, a method to characterize the magnitude of off-diagonal coupling terms in the power flow Jacobian is examined.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126863427","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965457
Qiang Zhang, V. Venkatasubramanian
The most critical part of the synchrophasor technology is the availability of accurate UTC time. Usually an external GPS clock device feeds PMU with 1 pulse per second time signals. During the second, PMU's internal clock keeps the pace until the next time signal arrives. Because of various reasons, time skews have been observed in some real life synchrophasor data. Two fundamental types of time skews are identified in this paper. Synchrophasor time skew problem is fundamentally different from that in SCADA system, because time shift is translated into error in phase angle measurements and subsequent errors in frequency and rate of change of frequency measurements. Algorithms are developed to automatically detect time skews online and to estimate the time errors. A correction method is also provided. Both simulated data and real life data are used to verify that the proposed methods are effective and accurate.
{"title":"Synchrophasor time skew: Formulation, detection and correction","authors":"Qiang Zhang, V. Venkatasubramanian","doi":"10.1109/NAPS.2014.6965457","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965457","url":null,"abstract":"The most critical part of the synchrophasor technology is the availability of accurate UTC time. Usually an external GPS clock device feeds PMU with 1 pulse per second time signals. During the second, PMU's internal clock keeps the pace until the next time signal arrives. Because of various reasons, time skews have been observed in some real life synchrophasor data. Two fundamental types of time skews are identified in this paper. Synchrophasor time skew problem is fundamentally different from that in SCADA system, because time shift is translated into error in phase angle measurements and subsequent errors in frequency and rate of change of frequency measurements. Algorithms are developed to automatically detect time skews online and to estimate the time errors. A correction method is also provided. Both simulated data and real life data are used to verify that the proposed methods are effective and accurate.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115743355","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965381
Bo Chen, K. Butler-Purry, A. Goulart, D. Kundur
Numerous innovative smart grid technologies are deployed in modern power systems, making a power system a typical cyber-physical system (CPS). The increasing coupling between a physical power system and its communication network requires a smart grid simulator to run in a cyber-physical environment for cyber security research. In addition, smart grid technologies introduce numerous access points to the communication network, making cyber security a big concern in smart grid planning and operation. In this paper, a simple real time CPS test bed, implemented in RTDS and OPNET, is discussed. The setup of the test bed is introduced. Results of a case study simulated in the test bed to study the impact of cyber attacks on system transient stability are presented. The simple test bed was capable of accurately modelling a smart grid while providing user-friendly modeling experience.
{"title":"Implementing a real-time cyber-physical system test bed in RTDS and OPNET","authors":"Bo Chen, K. Butler-Purry, A. Goulart, D. Kundur","doi":"10.1109/NAPS.2014.6965381","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965381","url":null,"abstract":"Numerous innovative smart grid technologies are deployed in modern power systems, making a power system a typical cyber-physical system (CPS). The increasing coupling between a physical power system and its communication network requires a smart grid simulator to run in a cyber-physical environment for cyber security research. In addition, smart grid technologies introduce numerous access points to the communication network, making cyber security a big concern in smart grid planning and operation. In this paper, a simple real time CPS test bed, implemented in RTDS and OPNET, is discussed. The setup of the test bed is introduced. Results of a case study simulated in the test bed to study the impact of cyber attacks on system transient stability are presented. The simple test bed was capable of accurately modelling a smart grid while providing user-friendly modeling experience.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114433545","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965452
L. Mathew, S. Chatterji
Pilot installations of STATCOM and UPFC have been built, commissioned and installed in the recent years. The high cost of these Voltage Source Converters (VSC) based FACTS controllers is found to be the major hindrance to their widespread use. Novel and cost effective FACTS topologies have been proposed which are built upon existing equipment which makes use of static converters. The different HPFC configurations devised by the investigator have been implemented on an SMIB system and simulated using MATLAB/ SIMULINK. The comparison of simulation results show that HPFC is a better option for damping power system oscillations and thus enhancing the stability of the system.
{"title":"Modeling and simulation of hybrid power flow controller implemented on SMIB system","authors":"L. Mathew, S. Chatterji","doi":"10.1109/NAPS.2014.6965452","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965452","url":null,"abstract":"Pilot installations of STATCOM and UPFC have been built, commissioned and installed in the recent years. The high cost of these Voltage Source Converters (VSC) based FACTS controllers is found to be the major hindrance to their widespread use. Novel and cost effective FACTS topologies have been proposed which are built upon existing equipment which makes use of static converters. The different HPFC configurations devised by the investigator have been implemented on an SMIB system and simulated using MATLAB/ SIMULINK. The comparison of simulation results show that HPFC is a better option for damping power system oscillations and thus enhancing the stability of the system.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"284 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114942926","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 : 2014-11-24DOI: 10.1109/NAPS.2014.6965390
M. Lauby, J. Bian, S. Ekisheva, M. Varghese
With higher penetrations of renewable energy resources, assessing frequency response trends becomes extremely important. It is a critical component to the reliable operation of the bulk power system, particularly during disturbances and restoration. This paper presents a new and comprehensive statistical method to evaluate the trends for the Eastern and Western Interconnections of the North American electric grid. The statistical analysis tests whether observable decreases or increases between four annual data points constitute a statistically significant trend. The probability distribution of frequency response and contributing factors to it changes over the years are also examined. The statistical significance tests and studies have indicated a stable general trend for the Eastern and Western Interconnections over time.
{"title":"Frequency response assessment of Eastern and Western Interconnections","authors":"M. Lauby, J. Bian, S. Ekisheva, M. Varghese","doi":"10.1109/NAPS.2014.6965390","DOIUrl":"https://doi.org/10.1109/NAPS.2014.6965390","url":null,"abstract":"With higher penetrations of renewable energy resources, assessing frequency response trends becomes extremely important. It is a critical component to the reliable operation of the bulk power system, particularly during disturbances and restoration. This paper presents a new and comprehensive statistical method to evaluate the trends for the Eastern and Western Interconnections of the North American electric grid. The statistical analysis tests whether observable decreases or increases between four annual data points constitute a statistically significant trend. The probability distribution of frequency response and contributing factors to it changes over the years are also examined. The statistical significance tests and studies have indicated a stable general trend for the Eastern and Western Interconnections over time.","PeriodicalId":421766,"journal":{"name":"2014 North American Power Symposium (NAPS)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130228623","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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