Pub Date : 2012-06-02DOI: 10.1109/IPEMC.2012.6259034
Kyung-Min Jin, Quách Ngọc Thịnh, Eel-Hwan Kim
This paper presents a method for compensating fault ride-through (FRT) of a wind turbine based on doubly-fed induction generator (DFIG) by using a dynamic voltage restorer (DVR). The performance of the DVR depends on its controller. Therefore, in this method, two controllers are proposed in the stationary and synchronous reference frame for DVR voltage regulation. A proportional-resonant (PR) controller is first designed in stationary frame. A proportional-integral (PI) controller is then proposed in the synchronous reference frame. The performance comparison of these two controllers in both transient and steady state responses are also carried out in this paper. With the proposed control method, the DVR can compensate for the FRT, while the DFIG wind turbine can continue its normal operation as demanded in actual grid codes. Simulation results using Psim simulation program are expressed for a 2 MW DFIG and a DVR system to validate the effectiveness of the proposed control methods during the FRT.
{"title":"DVR control of DFIG for compensating fault ride-through based on stationary and synchronous reference frame","authors":"Kyung-Min Jin, Quách Ngọc Thịnh, Eel-Hwan Kim","doi":"10.1109/IPEMC.2012.6259034","DOIUrl":"https://doi.org/10.1109/IPEMC.2012.6259034","url":null,"abstract":"This paper presents a method for compensating fault ride-through (FRT) of a wind turbine based on doubly-fed induction generator (DFIG) by using a dynamic voltage restorer (DVR). The performance of the DVR depends on its controller. Therefore, in this method, two controllers are proposed in the stationary and synchronous reference frame for DVR voltage regulation. A proportional-resonant (PR) controller is first designed in stationary frame. A proportional-integral (PI) controller is then proposed in the synchronous reference frame. The performance comparison of these two controllers in both transient and steady state responses are also carried out in this paper. With the proposed control method, the DVR can compensate for the FRT, while the DFIG wind turbine can continue its normal operation as demanded in actual grid codes. Simulation results using Psim simulation program are expressed for a 2 MW DFIG and a DVR system to validate the effectiveness of the proposed control methods during the FRT.","PeriodicalId":236136,"journal":{"name":"Proceedings of The 7th International Power Electronics and Motion Control Conference","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126438207","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 : 2012-06-02DOI: 10.1109/IPEMC.2012.6259202
Q. Liu, Lin Li, Hao Peng, Yan Deng, Xiangning He
In this paper, an improved droop control method is proposed for the parallel inverters in microgrids. The proposed strategy is based on the droop control technique, which only using the local measurable feedback information. This approach can be applied to the inverter-based microgrids where communication wires are not economic and reliable due to the distant physical locations. Unfortunately, the trade-off has to be made between the transient response and the power sharing accuracy for the conventional voltage and frequency droop control method. Moreover, the output and line impedance of the inverter presents a great impact on the power sharing accuracy. The proposed method takes into account the resistance of inverter output impedance and line impedance, and uses the active and reactive output current as the control variables, which limits the current spikes during the initial and transient states. Additionally, the derivate-integral terms are introduced to enhance the dynamic response of the inverters. Simulation results and experimental waveforms are given to validate the proposed control strategy.
{"title":"Improved droop control for parallel inverters in microgrids","authors":"Q. Liu, Lin Li, Hao Peng, Yan Deng, Xiangning He","doi":"10.1109/IPEMC.2012.6259202","DOIUrl":"https://doi.org/10.1109/IPEMC.2012.6259202","url":null,"abstract":"In this paper, an improved droop control method is proposed for the parallel inverters in microgrids. The proposed strategy is based on the droop control technique, which only using the local measurable feedback information. This approach can be applied to the inverter-based microgrids where communication wires are not economic and reliable due to the distant physical locations. Unfortunately, the trade-off has to be made between the transient response and the power sharing accuracy for the conventional voltage and frequency droop control method. Moreover, the output and line impedance of the inverter presents a great impact on the power sharing accuracy. The proposed method takes into account the resistance of inverter output impedance and line impedance, and uses the active and reactive output current as the control variables, which limits the current spikes during the initial and transient states. Additionally, the derivate-integral terms are introduced to enhance the dynamic response of the inverters. Simulation results and experimental waveforms are given to validate the proposed control strategy.","PeriodicalId":236136,"journal":{"name":"Proceedings of The 7th International Power Electronics and Motion Control Conference","volume":"10 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121300426","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 : 2012-06-02DOI: 10.1109/IPEMC.2012.6259029
Rui Li, Huiyu Zhu, Dianguo Xu
To improve the power rating of direct-drive wind turbine system, this paper proposes the parallel operation of two generator-side converters with interphase inductors. In the paper, the decoupling equivalent circuit and the zero-sequence circulating-current (ZSCC) models are derived. The fundamental mechanism of ZSCC suppression with interphase inductors is illustrated. Then the control strategy of the system is designed in the synchronous rotating coordinates. The ZSCCs are suppressed well and the discrepancy and distortion of currents are overcome. Therefore, the reliability and efficiency of the system are improved. Finally, the parallel generator-side converters with the power rating of 1.5 MW are simulated, which verifies the validity of the above analysis.
{"title":"Application of interphase inductors for parallel generator-side converters in direct-drive wind turbine system","authors":"Rui Li, Huiyu Zhu, Dianguo Xu","doi":"10.1109/IPEMC.2012.6259029","DOIUrl":"https://doi.org/10.1109/IPEMC.2012.6259029","url":null,"abstract":"To improve the power rating of direct-drive wind turbine system, this paper proposes the parallel operation of two generator-side converters with interphase inductors. In the paper, the decoupling equivalent circuit and the zero-sequence circulating-current (ZSCC) models are derived. The fundamental mechanism of ZSCC suppression with interphase inductors is illustrated. Then the control strategy of the system is designed in the synchronous rotating coordinates. The ZSCCs are suppressed well and the discrepancy and distortion of currents are overcome. Therefore, the reliability and efficiency of the system are improved. Finally, the parallel generator-side converters with the power rating of 1.5 MW are simulated, which verifies the validity of the above analysis.","PeriodicalId":236136,"journal":{"name":"Proceedings of The 7th International Power Electronics and Motion Control Conference","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121456834","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 : 2012-06-02DOI: 10.1109/IPEMC.2012.6259165
M. Shao, Ruiye Liu, Dianjun Lv
The voltage and frequency (V/F) of microgrid loss support when the operation of microgrid switches from grid-connected mode to islanded mode, therefore controlling of voltage and frequency is needed. A control strategy of voltage and frequency based on battery is proposed in this paper which purposed on regulating an islanded microgrid containing kinds of distributed generators (DG). According to the problem of traditional droop control of V/F that does not take into account of load structural changes, the control of battery introduces the voltage and current feedforward based on traditional V/F control strategy. Considering the variation of structure and parameter of the load is more suitable for practical power system. At the same time, aiming at the irreasonability caused by the equivalent source of photovoltaic (PV) system, this paper constructs the detailed system of PV. The validity of proposed control strategy is demonstrated through simulating the various states of searched microgrid.
{"title":"Control strategy of voltage and frequency for islanded microgrid","authors":"M. Shao, Ruiye Liu, Dianjun Lv","doi":"10.1109/IPEMC.2012.6259165","DOIUrl":"https://doi.org/10.1109/IPEMC.2012.6259165","url":null,"abstract":"The voltage and frequency (V/F) of microgrid loss support when the operation of microgrid switches from grid-connected mode to islanded mode, therefore controlling of voltage and frequency is needed. A control strategy of voltage and frequency based on battery is proposed in this paper which purposed on regulating an islanded microgrid containing kinds of distributed generators (DG). According to the problem of traditional droop control of V/F that does not take into account of load structural changes, the control of battery introduces the voltage and current feedforward based on traditional V/F control strategy. Considering the variation of structure and parameter of the load is more suitable for practical power system. At the same time, aiming at the irreasonability caused by the equivalent source of photovoltaic (PV) system, this paper constructs the detailed system of PV. The validity of proposed control strategy is demonstrated through simulating the various states of searched microgrid.","PeriodicalId":236136,"journal":{"name":"Proceedings of The 7th International Power Electronics and Motion Control Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121621969","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 : 2012-06-02DOI: 10.1109/IPEMC.2012.6259184
Jiarong Kan, Ning Li, Zhilei Yao, Y. Xue, Dongchun Wu
Using grid voltage feed-forward control, the current-loop parameters and filter inductor affect the power factor of grid-connected inverter. Based on droop phase-locked loop (PLL) a novel control strategy is proposed. The phase difference between the grid current and grid voltage is detected and is used to calculate the output frequency of PLL. Unity power factor can be achieved without affecting quality of grid current. The control block diagram is given. The operating principle of the proposed PLL and the selection guidance of droop coefficient are analyzed. The simulation and experimental results verify that the proposed method is effective in improving the power factor.
{"title":"Droop PLL for grid-connected inverter","authors":"Jiarong Kan, Ning Li, Zhilei Yao, Y. Xue, Dongchun Wu","doi":"10.1109/IPEMC.2012.6259184","DOIUrl":"https://doi.org/10.1109/IPEMC.2012.6259184","url":null,"abstract":"Using grid voltage feed-forward control, the current-loop parameters and filter inductor affect the power factor of grid-connected inverter. Based on droop phase-locked loop (PLL) a novel control strategy is proposed. The phase difference between the grid current and grid voltage is detected and is used to calculate the output frequency of PLL. Unity power factor can be achieved without affecting quality of grid current. The control block diagram is given. The operating principle of the proposed PLL and the selection guidance of droop coefficient are analyzed. The simulation and experimental results verify that the proposed method is effective in improving the power factor.","PeriodicalId":236136,"journal":{"name":"Proceedings of The 7th International Power Electronics and Motion Control Conference","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126602824","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}
In this paper, the driving strategy of the input split type series-parallel hybrid electric vehicle (SPHEV) is established with considering the energy efficiency and interpretation of dynamic characteristics for four kinds of HEV operation modes, such as electric vehicle mode (EV mode), engine mode, hybrid mode, and regeneration mode, are described. For this research, the simulation method based on the forward-facing approach is chosen, which is useful for the vehicle dynamic analysis. The rating of each powertrain components, such as planetary gear (PG), motor, energy storage system (ESS), and engine, is designed on the energy-based concept and the electrical peaking hybrid (ELPH) method. All powertrain components are designed individually and are controlled by a primary controller. Finally, the designed powertrain is evaluated with the developing of PSiM simulator.
{"title":"PSiM based establishment of driving strategy and dynamic analysis for input split type HEV","authors":"Taesuk Bae, Taekyu Kang, Jaeho Choi, Deokyoung Lim","doi":"10.1109/IPEMC.2012.6258822","DOIUrl":"https://doi.org/10.1109/IPEMC.2012.6258822","url":null,"abstract":"In this paper, the driving strategy of the input split type series-parallel hybrid electric vehicle (SPHEV) is established with considering the energy efficiency and interpretation of dynamic characteristics for four kinds of HEV operation modes, such as electric vehicle mode (EV mode), engine mode, hybrid mode, and regeneration mode, are described. For this research, the simulation method based on the forward-facing approach is chosen, which is useful for the vehicle dynamic analysis. The rating of each powertrain components, such as planetary gear (PG), motor, energy storage system (ESS), and engine, is designed on the energy-based concept and the electrical peaking hybrid (ELPH) method. All powertrain components are designed individually and are controlled by a primary controller. Finally, the designed powertrain is evaluated with the developing of PSiM simulator.","PeriodicalId":236136,"journal":{"name":"Proceedings of The 7th International Power Electronics and Motion Control Conference","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126607324","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 : 2012-06-02DOI: 10.1109/IPEMC.2012.6259080
Wen-Chen Zhang, N. Dai, M. Wong, Chikong Wong
The capacitive-coupled grid-connected inverter (CGCI) system is proposed in this paper. It can reduce the active power from the grid by injecting active power from the PV generators into the grid. The reactive power and harmonic compensation ability of the CGCI leads to reduced root-mean-square (RMS) value of source current and thus reduced residential power loss. The proposed CGCI and conventional inductive-coupled grid-connected inverter (IGCI) are compared. Results indicate that CGCI can achieve the required power delivery with lower inverter voltage rating. The proposed CGCI is utilized to integrate a PV generation system to the grid. Besides, reactive power and harmonic compensation is achieved simultaneously when the active power is injected. A dynamic reactive power adjustment block is added to the control system of the CGCI, which can improve its performance when the required reactive power compensation exceeds its control capability. Simulation results are provided to verify the validity of the CGCI and its control system.
{"title":"Capacitive-coupled grid-connected inverter with active power injection ability","authors":"Wen-Chen Zhang, N. Dai, M. Wong, Chikong Wong","doi":"10.1109/IPEMC.2012.6259080","DOIUrl":"https://doi.org/10.1109/IPEMC.2012.6259080","url":null,"abstract":"The capacitive-coupled grid-connected inverter (CGCI) system is proposed in this paper. It can reduce the active power from the grid by injecting active power from the PV generators into the grid. The reactive power and harmonic compensation ability of the CGCI leads to reduced root-mean-square (RMS) value of source current and thus reduced residential power loss. The proposed CGCI and conventional inductive-coupled grid-connected inverter (IGCI) are compared. Results indicate that CGCI can achieve the required power delivery with lower inverter voltage rating. The proposed CGCI is utilized to integrate a PV generation system to the grid. Besides, reactive power and harmonic compensation is achieved simultaneously when the active power is injected. A dynamic reactive power adjustment block is added to the control system of the CGCI, which can improve its performance when the required reactive power compensation exceeds its control capability. Simulation results are provided to verify the validity of the CGCI and its control system.","PeriodicalId":236136,"journal":{"name":"Proceedings of The 7th International Power Electronics and Motion Control Conference","volume":"49 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114128224","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 : 2012-06-02DOI: 10.1109/IPEMC.2012.6259102
Xiangjun Zhang, Binze Wang, Hao Ding, Dianguo Xu
Power factor correction (PFC) technology has gradually become an important subject in the field of power electronic research. CCM mode Boost PFC is the most commonly used topology in high power converting occasions. This paper presented a detailed analysis on working principle of CCM Boost PFC. Besides, according to the different states of inductor current and output current, the working mode of inductor energy supply can be devided into two types. In this paper the two working modes were analyzed, with the derivation of boundary conditions and the value of critical inductance. A 400W Boost PFC model was made on the basis of Simulink platform. The simulation waveforms and experimental results were presented at last.
{"title":"Study of CCM Boost PFC based on Simulink","authors":"Xiangjun Zhang, Binze Wang, Hao Ding, Dianguo Xu","doi":"10.1109/IPEMC.2012.6259102","DOIUrl":"https://doi.org/10.1109/IPEMC.2012.6259102","url":null,"abstract":"Power factor correction (PFC) technology has gradually become an important subject in the field of power electronic research. CCM mode Boost PFC is the most commonly used topology in high power converting occasions. This paper presented a detailed analysis on working principle of CCM Boost PFC. Besides, according to the different states of inductor current and output current, the working mode of inductor energy supply can be devided into two types. In this paper the two working modes were analyzed, with the derivation of boundary conditions and the value of critical inductance. A 400W Boost PFC model was made on the basis of Simulink platform. The simulation waveforms and experimental results were presented at last.","PeriodicalId":236136,"journal":{"name":"Proceedings of The 7th International Power Electronics and Motion Control Conference","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114216449","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 : 2012-06-02DOI: 10.1109/IPEMC.2012.6258897
H. Cui, Youichi Ito, Keisuke Nakano, Nobuaki Yokoyama, H. Bin
This paper describes the design of 100kVA EV (electric Vehicle) Charger which outputs 750V/150A. For the requirement of different type of EV, 13 units are in series; this can make the output voltage as the following: 40V–60V, 400V–600V or 500V–750V, and output voltage and current of each unit are 48V/150A. AC/DC of unit is Buck-type converter, this makes 350V of DC bus; it is very cheap for selection of power device of DC/DC. Resonant circuits are used in this part for high efficiency. It makes voltage of power device become zero before the power device turns on, so turn-on loss can be ignored. DC/DC part uses LLC resonant circuit, and power device can work in ZVS (zero voltage switching) condition and high frequency (about 100 kHz), so this part has high efficiency and small volume. To make charging faster and more security, two control loops are used in the power supply: one is voltage-loop and the other is current-loop. Power factor of input is above 0.99, and harmonic of input is less than 5%, the overall efficiency is more than 92% by charging experiment for bus.
{"title":"100kVA electric vehicle charger using resonant buck-type AC-DC converter","authors":"H. Cui, Youichi Ito, Keisuke Nakano, Nobuaki Yokoyama, H. Bin","doi":"10.1109/IPEMC.2012.6258897","DOIUrl":"https://doi.org/10.1109/IPEMC.2012.6258897","url":null,"abstract":"This paper describes the design of 100kVA EV (electric Vehicle) Charger which outputs 750V/150A. For the requirement of different type of EV, 13 units are in series; this can make the output voltage as the following: 40V–60V, 400V–600V or 500V–750V, and output voltage and current of each unit are 48V/150A. AC/DC of unit is Buck-type converter, this makes 350V of DC bus; it is very cheap for selection of power device of DC/DC. Resonant circuits are used in this part for high efficiency. It makes voltage of power device become zero before the power device turns on, so turn-on loss can be ignored. DC/DC part uses LLC resonant circuit, and power device can work in ZVS (zero voltage switching) condition and high frequency (about 100 kHz), so this part has high efficiency and small volume. To make charging faster and more security, two control loops are used in the power supply: one is voltage-loop and the other is current-loop. Power factor of input is above 0.99, and harmonic of input is less than 5%, the overall efficiency is more than 92% by charging experiment for bus.","PeriodicalId":236136,"journal":{"name":"Proceedings of The 7th International Power Electronics and Motion Control Conference","volume":"202 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114231223","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 : 2012-06-02DOI: 10.1109/IPEMC.2012.6258968
Q. Yu, C. Laudensack, D. Gerling
The can loss is the biggest constraint for canned drives at high speed. In this paper, the can loss of a canned switched reluctance machine (SRM) is analyzed. Then, the can loss is reduced by investigating topology of windings based on the spatial winding distribution theory. A new mathematical model is built up by considering arrangement of wires within a coil. The proposed winding topology is verified by simulation that not only can loss but iron loss can be suppressed at any speed and meanwhile the active torque is enhanced.
{"title":"Analysis and loss reduction of a canned switched reluctance drive from the windings perspective","authors":"Q. Yu, C. Laudensack, D. Gerling","doi":"10.1109/IPEMC.2012.6258968","DOIUrl":"https://doi.org/10.1109/IPEMC.2012.6258968","url":null,"abstract":"The can loss is the biggest constraint for canned drives at high speed. In this paper, the can loss of a canned switched reluctance machine (SRM) is analyzed. Then, the can loss is reduced by investigating topology of windings based on the spatial winding distribution theory. A new mathematical model is built up by considering arrangement of wires within a coil. The proposed winding topology is verified by simulation that not only can loss but iron loss can be suppressed at any speed and meanwhile the active torque is enhanced.","PeriodicalId":236136,"journal":{"name":"Proceedings of The 7th International Power Electronics and Motion Control Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121151974","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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