Pub Date : 2019-12-01DOI: 10.1109/COBEP/SPEC44138.2019.9065501
Lorena Lorraine Oliveira Albuquerque, Marcos Victor Dantas de Sá, Fellipe André Lucena de Oliveira, I. Soares de Freitas, R. Andersen
This paper proposes the mathematic model and the control of the current and voltage loops of the ZVS-PWM three-phase current-fed push-pull DC-DC converter. The converter has three ports, two bidirectional ports and one unidirectional port and can be used in various applications such as electric vehicles, battery charging system, fuel cell, isolated mini grids and micro grids. The proposed control is able to invert power flow by imposing main inductor current value and direction as well as maintaining voltage at a given port under load variations. The control structure for each case is presented, as well as the deduction of the main mathematical expressions. In order to validate the performance of the proposed control strategy, simulation results for a 500 W converter with 50V in port 1 and 200 V in port 3 and a switching frequency of 40 kHz are presented here.
{"title":"Dynamic Modeling and Control of a Three-Port ZVS-PWM Three-Phase Push Pull DC-DC Converter","authors":"Lorena Lorraine Oliveira Albuquerque, Marcos Victor Dantas de Sá, Fellipe André Lucena de Oliveira, I. Soares de Freitas, R. Andersen","doi":"10.1109/COBEP/SPEC44138.2019.9065501","DOIUrl":"https://doi.org/10.1109/COBEP/SPEC44138.2019.9065501","url":null,"abstract":"This paper proposes the mathematic model and the control of the current and voltage loops of the ZVS-PWM three-phase current-fed push-pull DC-DC converter. The converter has three ports, two bidirectional ports and one unidirectional port and can be used in various applications such as electric vehicles, battery charging system, fuel cell, isolated mini grids and micro grids. The proposed control is able to invert power flow by imposing main inductor current value and direction as well as maintaining voltage at a given port under load variations. The control structure for each case is presented, as well as the deduction of the main mathematical expressions. In order to validate the performance of the proposed control strategy, simulation results for a 500 W converter with 50V in port 1 and 200 V in port 3 and a switching frequency of 40 kHz are presented here.","PeriodicalId":69617,"journal":{"name":"电力电子","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81980315","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 : 2019-12-01DOI: 10.1109/COBEP/SPEC44138.2019.9065330
C. A. Caldeira, H. R. Schlickmann, A. D. de Almeida, L. V. Hartmann, C. Gehrke, F. Salvadori, Gilielson F. da Paz
With increasing use of intermittent renewable energy sources, energy storage is needed to maintain the balance between demand and supply. The renewable energy sources, e.g. solar and wind energy sources, are characterized by their intermittent generation, causing fluctuations in power generation, and, similarly, demand may vary. There may be fluctuations in power generation, and, similarly, demand may vary. Then, for these new sources become completely reliable as primary energy sources, energy storage is a crucial factor. This work uses real-time simulation to analyze the impact of battery-based energy storage systems on electrical systems. The simulator used is the OPAL-RT/5707™ real-time simulator, from OPAL-RT Technologies company. The simulated system consists of a three-phase inverter connected to a BESS (battery energy storage system) and to the electrical grid with variable loads. The obtained results from real-time simulations prove its effectiveness for this type of analysis and open the possibility to perform PHIL (power hardware in the loop) simulations.
{"title":"Modeling and Simulation of the Battery Energy Storage System for Analysis Impact in the Electrical Grid.","authors":"C. A. Caldeira, H. R. Schlickmann, A. D. de Almeida, L. V. Hartmann, C. Gehrke, F. Salvadori, Gilielson F. da Paz","doi":"10.1109/COBEP/SPEC44138.2019.9065330","DOIUrl":"https://doi.org/10.1109/COBEP/SPEC44138.2019.9065330","url":null,"abstract":"With increasing use of intermittent renewable energy sources, energy storage is needed to maintain the balance between demand and supply. The renewable energy sources, e.g. solar and wind energy sources, are characterized by their intermittent generation, causing fluctuations in power generation, and, similarly, demand may vary. There may be fluctuations in power generation, and, similarly, demand may vary. Then, for these new sources become completely reliable as primary energy sources, energy storage is a crucial factor. This work uses real-time simulation to analyze the impact of battery-based energy storage systems on electrical systems. The simulator used is the OPAL-RT/5707™ real-time simulator, from OPAL-RT Technologies company. The simulated system consists of a three-phase inverter connected to a BESS (battery energy storage system) and to the electrical grid with variable loads. The obtained results from real-time simulations prove its effectiveness for this type of analysis and open the possibility to perform PHIL (power hardware in the loop) simulations.","PeriodicalId":69617,"journal":{"name":"电力电子","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81995003","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 : 2019-12-01DOI: 10.1109/COBEP/SPEC44138.2019.9065423
Rafael H. Eckstein, T. Lazzarin, G. Waltrich
It is no exaggeration to consider electric vehicles a reality in our current society. Comparing to combustion vehicles they have better efficiency and monetary profitability by distance traveled. However, the necessary infrastructure for the proper functioning of EVs, as batteries, individual chargers, charge stations, etc., are still precarious in several places. This paper introduces a new interleaved model for a low voltage battery pack charger for neighborhood electric vehicles (NEV). The system has two power stages, a SEPIC PFC rectifier and a DC-DC Buck converter, which process 1.5 kW per cell a total of 4.5 kW. The proposed system is adequate to lower power single-phase systems, which the battery pack voltage is lower than the grid.
{"title":"Two-Stage SEPIC-Buck Topology for Neighborhood Electric Vehicle Charger","authors":"Rafael H. Eckstein, T. Lazzarin, G. Waltrich","doi":"10.1109/COBEP/SPEC44138.2019.9065423","DOIUrl":"https://doi.org/10.1109/COBEP/SPEC44138.2019.9065423","url":null,"abstract":"It is no exaggeration to consider electric vehicles a reality in our current society. Comparing to combustion vehicles they have better efficiency and monetary profitability by distance traveled. However, the necessary infrastructure for the proper functioning of EVs, as batteries, individual chargers, charge stations, etc., are still precarious in several places. This paper introduces a new interleaved model for a low voltage battery pack charger for neighborhood electric vehicles (NEV). The system has two power stages, a SEPIC PFC rectifier and a DC-DC Buck converter, which process 1.5 kW per cell a total of 4.5 kW. The proposed system is adequate to lower power single-phase systems, which the battery pack voltage is lower than the grid.","PeriodicalId":69617,"journal":{"name":"电力电子","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76118519","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 : 2019-12-01DOI: 10.1109/COBEP/SPEC44138.2019.9065748
D. C. Morais, Falcondes José Mendes de Seixas, Luís de Oro Arenas, Lucas Carvalho Souza, Luciano de Souza da Costa e Silva
In this paper, a bridgeless buck-boost converter with power factor correction is proposed, using a three-state switching cell named of B configuration, operating in continuous conduction mode. The bridgeless technique allows the bridge rectifier inclusion switched on power grid frequency, in the high frequency DC-DC converter stage, reducing the stages number required and increasing the structure reliability. Due to three-state switching cell configuration, there is a current stress division by half of the inductor current in all of circuit semiconductors. Moreover, the ripple frequency on converter energy storage elements is twice switching frequency value, which make easier the design of input and output passive filters and reduces the converter’s volume and weight. Preliminary simulation results prove the converter effectiveness on power factor correction, keeping output voltage stable in a specified operation point, with a total harmonic distortion of the input current less than 2%.
{"title":"Bridgeless Buck-Boost PFC Converter with Three-State Switching Cell","authors":"D. C. Morais, Falcondes José Mendes de Seixas, Luís de Oro Arenas, Lucas Carvalho Souza, Luciano de Souza da Costa e Silva","doi":"10.1109/COBEP/SPEC44138.2019.9065748","DOIUrl":"https://doi.org/10.1109/COBEP/SPEC44138.2019.9065748","url":null,"abstract":"In this paper, a bridgeless buck-boost converter with power factor correction is proposed, using a three-state switching cell named of B configuration, operating in continuous conduction mode. The bridgeless technique allows the bridge rectifier inclusion switched on power grid frequency, in the high frequency DC-DC converter stage, reducing the stages number required and increasing the structure reliability. Due to three-state switching cell configuration, there is a current stress division by half of the inductor current in all of circuit semiconductors. Moreover, the ripple frequency on converter energy storage elements is twice switching frequency value, which make easier the design of input and output passive filters and reduces the converter’s volume and weight. Preliminary simulation results prove the converter effectiveness on power factor correction, keeping output voltage stable in a specified operation point, with a total harmonic distortion of the input current less than 2%.","PeriodicalId":69617,"journal":{"name":"电力电子","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79466087","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 : 2019-12-01DOI: 10.1109/COBEP/SPEC44138.2019.9065493
I. F. Carvalho, M. Corrêa
Due to the increasing proportion of photovoltaic production in the electric generation mix, it is important to know the capacity of photovoltaic generation to estimate the efficiency of the solar power plant in any condition and thus to predict the point where the maximum power is converted. The process of converting solar energy into electrical energy is directly influenced by the level of irradiance and temperature of the photovoltaic module. In this way, equipment and tools that enable the acquisition of such data contribute directly to the knowledge of the efficiency of the photovoltaic system. While the acquisition of temperature values in photovoltaic panels is easy to implement, the same does not occur for irradiance values, where the costs of the sensors and their calibration are some of the problems faced. With the objective of exploring and comparing irradiance estimation techniques, the present work presents four solar radiation estimation algorithms, based on PV panel datasheet.
{"title":"Techniques of Solar Irradiance Estimation from Datasheet Information of Photovoltaic Panels","authors":"I. F. Carvalho, M. Corrêa","doi":"10.1109/COBEP/SPEC44138.2019.9065493","DOIUrl":"https://doi.org/10.1109/COBEP/SPEC44138.2019.9065493","url":null,"abstract":"Due to the increasing proportion of photovoltaic production in the electric generation mix, it is important to know the capacity of photovoltaic generation to estimate the efficiency of the solar power plant in any condition and thus to predict the point where the maximum power is converted. The process of converting solar energy into electrical energy is directly influenced by the level of irradiance and temperature of the photovoltaic module. In this way, equipment and tools that enable the acquisition of such data contribute directly to the knowledge of the efficiency of the photovoltaic system. While the acquisition of temperature values in photovoltaic panels is easy to implement, the same does not occur for irradiance values, where the costs of the sensors and their calibration are some of the problems faced. With the objective of exploring and comparing irradiance estimation techniques, the present work presents four solar radiation estimation algorithms, based on PV panel datasheet.","PeriodicalId":69617,"journal":{"name":"电力电子","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76711068","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 : 2019-12-01DOI: 10.1109/COBEP/SPEC44138.2019.9065674
Vitor C. S. Torres, Vinícius M. de Albuquerque, M. A. Rendón, P. S. Almeida, J. G. Oliveira, M. Rodrigues
This paper presents the development of a state-space-based modeling approach for an interleaved bidirectional DC-DC converter, which is part of an aircraft hybrid propulsion system. The proposed model is presented in order to obtain relationships of voltage and current control loops of two operational modes of this interleaved DC-DC converter: buck mode, which controls voltage and current during on-board battery pack charging; and boost mode, responsible for aircraft hybrid propulsion system DC bus regulation. Simulation results are used to validate the developed model as well as to evaluate control system performance.
{"title":"Interleaved Bidirectional DC-DC Converter for Application in Hybrid Propulsion System: Modeling and Control","authors":"Vitor C. S. Torres, Vinícius M. de Albuquerque, M. A. Rendón, P. S. Almeida, J. G. Oliveira, M. Rodrigues","doi":"10.1109/COBEP/SPEC44138.2019.9065674","DOIUrl":"https://doi.org/10.1109/COBEP/SPEC44138.2019.9065674","url":null,"abstract":"This paper presents the development of a state-space-based modeling approach for an interleaved bidirectional DC-DC converter, which is part of an aircraft hybrid propulsion system. The proposed model is presented in order to obtain relationships of voltage and current control loops of two operational modes of this interleaved DC-DC converter: buck mode, which controls voltage and current during on-board battery pack charging; and boost mode, responsible for aircraft hybrid propulsion system DC bus regulation. Simulation results are used to validate the developed model as well as to evaluate control system performance.","PeriodicalId":69617,"journal":{"name":"电力电子","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76934815","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 : 2019-12-01DOI: 10.1109/COBEP/SPEC44138.2019.9065733
Eliabe Duarte Queiroz, J. Antenor Pomilio
A SRF-PLL model considering voltage influences is used to develop a state-space model of a current source converter operating on droop mode. The linear and non-linear models are simulated with two different frequency estimations. Due to the frequency estimation, an instability arises in the non-linear simulation and it is verified in the linear model. Comparisons are made between the linear and non-linear models.
{"title":"SRF-PLL Influence on the Stability of a Current Source Converter in Droop Mode","authors":"Eliabe Duarte Queiroz, J. Antenor Pomilio","doi":"10.1109/COBEP/SPEC44138.2019.9065733","DOIUrl":"https://doi.org/10.1109/COBEP/SPEC44138.2019.9065733","url":null,"abstract":"A SRF-PLL model considering voltage influences is used to develop a state-space model of a current source converter operating on droop mode. The linear and non-linear models are simulated with two different frequency estimations. Due to the frequency estimation, an instability arises in the non-linear simulation and it is verified in the linear model. Comparisons are made between the linear and non-linear models.","PeriodicalId":69617,"journal":{"name":"电力电子","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77417087","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 : 2019-12-01DOI: 10.1109/COBEP/SPEC44138.2019.9065814
Eduardo Luiz Santos da Silva, André Luís Kirsten, D. Pagano
This article presents the design and evaluation of a discrete non-linear controller with bilinear approximation to regulate the output voltage of a Dual Active Bridge (DAB) converter under parametric uncertainties. In this paper we consider the possible uncertainties in the system, such as variations in load and input voltage. The drive is controlled by single phase shift modulation (SPS) with a fixed duty cycle. The discrete controller developed ensures disturbance rejection, reference tracking and zero overshoot, with a small transient regime. The results obtained through the Typhoon HIL are presented to validate the effectiveness of the developed controller.
{"title":"Discrete SPS Control of a DAB converter using partial Feedback Linearization","authors":"Eduardo Luiz Santos da Silva, André Luís Kirsten, D. Pagano","doi":"10.1109/COBEP/SPEC44138.2019.9065814","DOIUrl":"https://doi.org/10.1109/COBEP/SPEC44138.2019.9065814","url":null,"abstract":"This article presents the design and evaluation of a discrete non-linear controller with bilinear approximation to regulate the output voltage of a Dual Active Bridge (DAB) converter under parametric uncertainties. In this paper we consider the possible uncertainties in the system, such as variations in load and input voltage. The drive is controlled by single phase shift modulation (SPS) with a fixed duty cycle. The discrete controller developed ensures disturbance rejection, reference tracking and zero overshoot, with a small transient regime. The results obtained through the Typhoon HIL are presented to validate the effectiveness of the developed controller.","PeriodicalId":69617,"journal":{"name":"电力电子","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79111271","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 : 2019-12-01DOI: 10.1109/COBEP/SPEC44138.2019.9065847
Dênis de Castro Pereira, Rúbio Campos Marques, P. S. Almeida, G. M. Soares, F. L. Tofoli, P. L. Tavares, Henrique Antônio Carvalho Braga
This work lies on the active cooling and thermal evaluation applied to an extra-high current (up to 12 A) chip-on-board (COB) light-emitting diode (LED). Simulations are performed employing computational fluid dynamics (CFD) so that the main thermal parameters can be obtained as close as possible to real results. Aiming at a thorough analysis of heat dissipation at very high current levels in floodlighting applications, a finite element analysis is carried out in order to establish a comparative approach concerning the convected air flow through a volume-reduced fin-heatsink. The simulated results show that the lighting system can be significantly improved by employing such active cooling technique for the device’s power rated condition (i.e., 350 W). For this operating point, the manufacturer’s heatsink physical volume could be decreased by 87% when applying the active cooling system with convected air flux, while also ensuring a safe thermal operation under maximum junction temperature of 120 °C.
{"title":"Active Cooling and Thermal Simulation Applied to an Extra-High Current COB LED","authors":"Dênis de Castro Pereira, Rúbio Campos Marques, P. S. Almeida, G. M. Soares, F. L. Tofoli, P. L. Tavares, Henrique Antônio Carvalho Braga","doi":"10.1109/COBEP/SPEC44138.2019.9065847","DOIUrl":"https://doi.org/10.1109/COBEP/SPEC44138.2019.9065847","url":null,"abstract":"This work lies on the active cooling and thermal evaluation applied to an extra-high current (up to 12 A) chip-on-board (COB) light-emitting diode (LED). Simulations are performed employing computational fluid dynamics (CFD) so that the main thermal parameters can be obtained as close as possible to real results. Aiming at a thorough analysis of heat dissipation at very high current levels in floodlighting applications, a finite element analysis is carried out in order to establish a comparative approach concerning the convected air flow through a volume-reduced fin-heatsink. The simulated results show that the lighting system can be significantly improved by employing such active cooling technique for the device’s power rated condition (i.e., 350 W). For this operating point, the manufacturer’s heatsink physical volume could be decreased by 87% when applying the active cooling system with convected air flux, while also ensuring a safe thermal operation under maximum junction temperature of 120 °C.","PeriodicalId":69617,"journal":{"name":"电力电子","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73418279","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 : 2019-12-01DOI: 10.1109/COBEP/SPEC44138.2019.9065499
Valesca Bettim Feltrin, Thiago Brezolin Dalmolin, L. Bellinaso, L. Michels
Equivalent grid impedance is an important information for testing control stability of grid-connected inverters. Furthermore, grid impedance parameters impact on local grid voltage when the local load or generator changes its active and reactive power. In grid connection standards such as the Brazilian Association of Technical Standards (ABNT) Brazilian Regulatory Standard (NBR) 16149, Photovoltaic (PV) inverters higher than 6 kW shall have external control of active and reactive power. This manuscript proposes a methodology for experimental determination of grid impedance by using the external commands of PV inverters. Experimental results were obtained with a 100 kW inverter of a photovoltaic power plant, and then the local grid impedance was calculated. Finally, the impedance calculation was validated in simulation.
{"title":"Methodology for experimental determination of equivalent grid impedance by using external commands of PV inverters","authors":"Valesca Bettim Feltrin, Thiago Brezolin Dalmolin, L. Bellinaso, L. Michels","doi":"10.1109/COBEP/SPEC44138.2019.9065499","DOIUrl":"https://doi.org/10.1109/COBEP/SPEC44138.2019.9065499","url":null,"abstract":"Equivalent grid impedance is an important information for testing control stability of grid-connected inverters. Furthermore, grid impedance parameters impact on local grid voltage when the local load or generator changes its active and reactive power. In grid connection standards such as the Brazilian Association of Technical Standards (ABNT) Brazilian Regulatory Standard (NBR) 16149, Photovoltaic (PV) inverters higher than 6 kW shall have external control of active and reactive power. This manuscript proposes a methodology for experimental determination of grid impedance by using the external commands of PV inverters. Experimental results were obtained with a 100 kW inverter of a photovoltaic power plant, and then the local grid impedance was calculated. Finally, the impedance calculation was validated in simulation.","PeriodicalId":69617,"journal":{"name":"电力电子","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75439653","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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