Pub Date : 2012-12-24DOI: 10.1109/ESARS.2012.6387418
E. Chiodo, D. Lauria
It is widely recognized that one of the crucial point for designing and planning electrical power system is the load characterization. The problem is well known and analyzed for any power system - since peak demand may exceed the maximum generated power, resulting in power outages and load shedding - but it is particularly cumbersome for railway and light transportation systems. In these cases indeed the loads exhibit fast changes and a large degree of randomness, whose description requires a proper analysis by using stochastic processes. In particular, it is of interest to have information about the extreme value of the stochastic load process in time for properly designing the generation and distribution system, and the storage devices. In the paper a new efficient estimation algorithm for the frequency of peak load occurrences is proposed. The core of the procedure, which is easily extensible to other peak load parameters, is based upon the assumption that the peak power is a Poisson process. In the paper, after a proper probabilistic description, attention is focused on the estimation of the above frequency by means of a suitable Bayesian estimation technique. Finally, the summary of a large set of numerical simulations is presented, which show the high efficiency of such estimation methodology.
{"title":"Probabilistic description and prediction of electric peak power demand","authors":"E. Chiodo, D. Lauria","doi":"10.1109/ESARS.2012.6387418","DOIUrl":"https://doi.org/10.1109/ESARS.2012.6387418","url":null,"abstract":"It is widely recognized that one of the crucial point for designing and planning electrical power system is the load characterization. The problem is well known and analyzed for any power system - since peak demand may exceed the maximum generated power, resulting in power outages and load shedding - but it is particularly cumbersome for railway and light transportation systems. In these cases indeed the loads exhibit fast changes and a large degree of randomness, whose description requires a proper analysis by using stochastic processes. In particular, it is of interest to have information about the extreme value of the stochastic load process in time for properly designing the generation and distribution system, and the storage devices. In the paper a new efficient estimation algorithm for the frequency of peak load occurrences is proposed. The core of the procedure, which is easily extensible to other peak load parameters, is based upon the assumption that the peak power is a Poisson process. In the paper, after a proper probabilistic description, attention is focused on the estimation of the above frequency by means of a suitable Bayesian estimation technique. Finally, the summary of a large set of numerical simulations is presented, which show the high efficiency of such estimation methodology.","PeriodicalId":243822,"journal":{"name":"2012 Electrical Systems for Aircraft, Railway and Ship Propulsion","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115232725","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 : 2012-12-24DOI: 10.1109/ESARS.2012.6387462
Fabrizio Re
Airport ground operations have a great impact on the surrounding environment. Many have proposed or are studying innovative systems to perform taxi without use of the main engines. This would result in cleaner and quieter airport operations, as well as in improved fuel efficiency. In this paper, the possibilities and limitations of such systems are discussed considering real scenarios and constraints. The technical challenges that determine their viability and integrability into the aircraft or airport, as well as the expected benefits and issues are addressed. Finally, the most important current research and development projects are presented.
{"title":"Viability and state of the art of environmentally friendly aircraft taxiing systems","authors":"Fabrizio Re","doi":"10.1109/ESARS.2012.6387462","DOIUrl":"https://doi.org/10.1109/ESARS.2012.6387462","url":null,"abstract":"Airport ground operations have a great impact on the surrounding environment. Many have proposed or are studying innovative systems to perform taxi without use of the main engines. This would result in cleaner and quieter airport operations, as well as in improved fuel efficiency. In this paper, the possibilities and limitations of such systems are discussed considering real scenarios and constraints. The technical challenges that determine their viability and integrability into the aircraft or airport, as well as the expected benefits and issues are addressed. Finally, the most important current research and development projects are presented.","PeriodicalId":243822,"journal":{"name":"2012 Electrical Systems for Aircraft, Railway and Ship Propulsion","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115670378","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 : 2012-12-24DOI: 10.1109/ESARS.2012.6387466
A. Kuperman, S. Arogeti, Z. Brand, Q. Zhong
In this paper, a feedback linearization control strategy, robustified by an uncertainty and disturbance estimator (UDE) is proposed for a two axis active magnetic bearing (AMB). An experimentally derived dynamical model of an AMB, employed in a flywheel, is utilized. The couplings between the axes as well as the uncertainties are treated as additional disturbances to the system. These terms are quickly estimated and compensated by an UDE observer, allowing the classical feedback linearization controller to operate on a nearly nominal system. Extended simulation results are presented to demonstrate the feasibility and effectiveness of the proposed control structure.
{"title":"Robust UDE-based control of active magnetic bearing for flywheel applications","authors":"A. Kuperman, S. Arogeti, Z. Brand, Q. Zhong","doi":"10.1109/ESARS.2012.6387466","DOIUrl":"https://doi.org/10.1109/ESARS.2012.6387466","url":null,"abstract":"In this paper, a feedback linearization control strategy, robustified by an uncertainty and disturbance estimator (UDE) is proposed for a two axis active magnetic bearing (AMB). An experimentally derived dynamical model of an AMB, employed in a flywheel, is utilized. The couplings between the axes as well as the uncertainties are treated as additional disturbances to the system. These terms are quickly estimated and compensated by an UDE observer, allowing the classical feedback linearization controller to operate on a nearly nominal system. Extended simulation results are presented to demonstrate the feasibility and effectiveness of the proposed control structure.","PeriodicalId":243822,"journal":{"name":"2012 Electrical Systems for Aircraft, Railway and Ship Propulsion","volume":"153 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123086638","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 : 2012-12-24DOI: 10.1109/ESARS.2012.6387390
Zha Wenqi, Wang Li, Chen Wei
Wire on-line detection technology is significant to aircraft wire fault diagnosis. Spread Spectral Time Domain Reflectometry (SSTDR), which is an effective method for wire fault detection on-line, is studied and analyzed in this paper for aviation field. Simulation platform and experimental system with FPGA as the core are established. Based on test results, this method is verified to be effective on real-time detection of wire carrying 115V/400HZ AC power signal. Through the analysis of theory and experiments, its detection accuracy and application field are obtained.
{"title":"Theoretical and experimental study of Spread Spectral Domain Reflectometry","authors":"Zha Wenqi, Wang Li, Chen Wei","doi":"10.1109/ESARS.2012.6387390","DOIUrl":"https://doi.org/10.1109/ESARS.2012.6387390","url":null,"abstract":"Wire on-line detection technology is significant to aircraft wire fault diagnosis. Spread Spectral Time Domain Reflectometry (SSTDR), which is an effective method for wire fault detection on-line, is studied and analyzed in this paper for aviation field. Simulation platform and experimental system with FPGA as the core are established. Based on test results, this method is verified to be effective on real-time detection of wire carrying 115V/400HZ AC power signal. Through the analysis of theory and experiments, its detection accuracy and application field are obtained.","PeriodicalId":243822,"journal":{"name":"2012 Electrical Systems for Aircraft, Railway and Ship Propulsion","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120842077","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 : 2012-12-24DOI: 10.1109/ESARS.2012.6387471
Tao Yang, S. Bozhko, G. Asher
The paper develops a diode-bridge rectifier model based on dynamic phasors (DP) concept. The model is targeted at the functional modeling level according to the multi-layer modeling definition. The performance and efficiency of the developed model have been revealed by comparison against abc three-phase model and dq0 functional model under balanced and unbalanced conditions. The comparison shows the DP model is more accurate than dq0 model in the discontinuous dc-link current case and is the fastest model under unbalanced conditions. The interface between DP models and normal time-domain three-phase systems is also introduced, which allows combination of the DP model with other standard three-phase models and make the application of the DP model more convenient.
{"title":"Modeling of uncontrolled rectifiers using dynamic phasors","authors":"Tao Yang, S. Bozhko, G. Asher","doi":"10.1109/ESARS.2012.6387471","DOIUrl":"https://doi.org/10.1109/ESARS.2012.6387471","url":null,"abstract":"The paper develops a diode-bridge rectifier model based on dynamic phasors (DP) concept. The model is targeted at the functional modeling level according to the multi-layer modeling definition. The performance and efficiency of the developed model have been revealed by comparison against abc three-phase model and dq0 functional model under balanced and unbalanced conditions. The comparison shows the DP model is more accurate than dq0 model in the discontinuous dc-link current case and is the fastest model under unbalanced conditions. The interface between DP models and normal time-domain three-phase systems is also introduced, which allows combination of the DP model with other standard three-phase models and make the application of the DP model more convenient.","PeriodicalId":243822,"journal":{"name":"2012 Electrical Systems for Aircraft, Railway and Ship Propulsion","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126736677","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 : 2012-12-24DOI: 10.1109/ESARS.2012.6387498
I. Boldea, L. Tutelea, S. Deaconu, F. Marignetti
In an effort to simplify the planetary-geared e-CVT for the parallel HEV or the series HEV we hereby propose-in a synthesis of these authors quite a few previous recent IEEExplore papers on the subject- to replace the basically two electric machines and their two power converters by a single, axial-air-gap, electric machine central stator, fed from a single PWM converter with dual frequency voltage output and two independent PM rotors capable to deliver independently torque by adequate vector control. The paper presents preliminary design with Matlab, optimal design via Hooke Jeeves method, sample quasi-2D and 3-D FEM results and dual vector control of a synchronous machine with axial air-gap single stator dual-rotor with permanent surface magnets and different pole pair's number, destined for hybrid electric vehicles (HEV) applications. For machine's designing the equivalent 3D magnetic circuits method, that takes into account the saturation and the magnetic field fringing, was used. A control model is developed for a single inverter that produces three phase output voltages with two frequency components. The modeling and performance characterization, and dual vector control show promising results, but experiments, which are now in preparation, are needed to prove the practicality of the proposed system.
{"title":"Dual rotor single- stator axial air gap PMSM motor/generator drive for HEVs: A review of comprehensive modeling and performance characterization","authors":"I. Boldea, L. Tutelea, S. Deaconu, F. Marignetti","doi":"10.1109/ESARS.2012.6387498","DOIUrl":"https://doi.org/10.1109/ESARS.2012.6387498","url":null,"abstract":"In an effort to simplify the planetary-geared e-CVT for the parallel HEV or the series HEV we hereby propose-in a synthesis of these authors quite a few previous recent IEEExplore papers on the subject- to replace the basically two electric machines and their two power converters by a single, axial-air-gap, electric machine central stator, fed from a single PWM converter with dual frequency voltage output and two independent PM rotors capable to deliver independently torque by adequate vector control. The paper presents preliminary design with Matlab, optimal design via Hooke Jeeves method, sample quasi-2D and 3-D FEM results and dual vector control of a synchronous machine with axial air-gap single stator dual-rotor with permanent surface magnets and different pole pair's number, destined for hybrid electric vehicles (HEV) applications. For machine's designing the equivalent 3D magnetic circuits method, that takes into account the saturation and the magnetic field fringing, was used. A control model is developed for a single inverter that produces three phase output voltages with two frequency components. The modeling and performance characterization, and dual vector control show promising results, but experiments, which are now in preparation, are needed to prove the practicality of the proposed system.","PeriodicalId":243822,"journal":{"name":"2012 Electrical Systems for Aircraft, Railway and Ship Propulsion","volume":"126 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122491780","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 : 2012-12-24DOI: 10.1109/ESARS.2012.6387489
O. Veneri, F. Migliardini, C. Capasso, P. Corbo
In this paper some preliminary experimental results on a Zebra battery based propulsion system for urban bus applications are presented. The tests were carried out using a laboratory 1:1 scale test bench, composed by a 65 kW electric drive, specifically designed for urban bus applications, supplied by two 20 kWh Zebra batteries connected in parallel. The electric power train was tested on a laboratory bench, connected through a fixed ratio gear box to a 100 kW regenerative electric brake provided with speed and torque controls, in order to evaluate the propulsion system performance in steady state operative conditions. The obtained preliminary experimental results were utilized to implement a Matlab-Simulink model of urban bus, which might be powered by the same electric propulsion system studied. Thanks to this model it was possible to evaluate the dynamic behavior of the urban bus, working on standard driving cycles, taking into account the resistant forces represented by proper vehicle/road/aerodynamic parameters. An evaluation of the expected real vehicle driving range was also estimated in different road conditions.
{"title":"ZEBRA battery based propulsion system for urban bus applications: Preliminary laboratory tests","authors":"O. Veneri, F. Migliardini, C. Capasso, P. Corbo","doi":"10.1109/ESARS.2012.6387489","DOIUrl":"https://doi.org/10.1109/ESARS.2012.6387489","url":null,"abstract":"In this paper some preliminary experimental results on a Zebra battery based propulsion system for urban bus applications are presented. The tests were carried out using a laboratory 1:1 scale test bench, composed by a 65 kW electric drive, specifically designed for urban bus applications, supplied by two 20 kWh Zebra batteries connected in parallel. The electric power train was tested on a laboratory bench, connected through a fixed ratio gear box to a 100 kW regenerative electric brake provided with speed and torque controls, in order to evaluate the propulsion system performance in steady state operative conditions. The obtained preliminary experimental results were utilized to implement a Matlab-Simulink model of urban bus, which might be powered by the same electric propulsion system studied. Thanks to this model it was possible to evaluate the dynamic behavior of the urban bus, working on standard driving cycles, taking into account the resistant forces represented by proper vehicle/road/aerodynamic parameters. An evaluation of the expected real vehicle driving range was also estimated in different road conditions.","PeriodicalId":243822,"journal":{"name":"2012 Electrical Systems for Aircraft, Railway and Ship Propulsion","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122657032","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 : 2012-12-24DOI: 10.1109/ESARS.2012.6387417
F. Ciccarelli, M. Fantauzzi, D. Lauria, R. Rizzo
This paper deals with special transformer connections for mitigating the current and voltage unbalances generated by single-phase AC traction loads, as typically occurs for electric high speed railway loads supplied by the three phase power system. In fact they represent one of the main sources of power quality perturbation of the grid, with consequent denigration of its performance. The current unbalance reduces efficiency, productivity and profits at the generation, transmission and distribution of electric energy. Voltage asymmetry reduces efficiency, productivity and profits at the consumption and utilization level. Transformer connections for mitigating these perturbations are summarized and compared each other. These mainly consist on different types of connections of single-phase transformers of the substation to the three-phase primary section with phase-transformation methods. Finally, an advanced scheme for current balancing and power factor improving of two unbalanced loads is performed.
{"title":"Special transformers arrangement for AC railway systems","authors":"F. Ciccarelli, M. Fantauzzi, D. Lauria, R. Rizzo","doi":"10.1109/ESARS.2012.6387417","DOIUrl":"https://doi.org/10.1109/ESARS.2012.6387417","url":null,"abstract":"This paper deals with special transformer connections for mitigating the current and voltage unbalances generated by single-phase AC traction loads, as typically occurs for electric high speed railway loads supplied by the three phase power system. In fact they represent one of the main sources of power quality perturbation of the grid, with consequent denigration of its performance. The current unbalance reduces efficiency, productivity and profits at the generation, transmission and distribution of electric energy. Voltage asymmetry reduces efficiency, productivity and profits at the consumption and utilization level. Transformer connections for mitigating these perturbations are summarized and compared each other. These mainly consist on different types of connections of single-phase transformers of the substation to the three-phase primary section with phase-transformation methods. Finally, an advanced scheme for current balancing and power factor improving of two unbalanced loads is performed.","PeriodicalId":243822,"journal":{"name":"2012 Electrical Systems for Aircraft, Railway and Ship Propulsion","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124642843","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 : 2012-12-24DOI: 10.1109/ESARS.2012.6387428
J. Igelspacher, Q. Hecker, H. Herzog
In this paper a method for simulating an axial-flux induction machine with squirrel cage is presented. The Simulation is based on the multiple coupled circuit theory wherein the needed inductances are calculated with the winding function theory. This simulation model is the basis for fault simulations like short circuits. First, the principle arrangement and the machine data are shown. After a short introduction to the winding function and multiple circuit theory the calculation of the self- and mutual- inductances based on its Fourier series is explained. Moreover the difference between using a rectangular and a trapezoidal characteristic of the winding function is described. Especially for this type of machine the needed assumptions and simplifications are presented as well. In a next step the simulation model implemented in Matlab/Simulink is presented. The paper ends with some simulation results compared to the machine data and a short conclusion.
{"title":"Simulation of an axial-flux induction machine with squirrel cage based on the winding function theory","authors":"J. Igelspacher, Q. Hecker, H. Herzog","doi":"10.1109/ESARS.2012.6387428","DOIUrl":"https://doi.org/10.1109/ESARS.2012.6387428","url":null,"abstract":"In this paper a method for simulating an axial-flux induction machine with squirrel cage is presented. The Simulation is based on the multiple coupled circuit theory wherein the needed inductances are calculated with the winding function theory. This simulation model is the basis for fault simulations like short circuits. First, the principle arrangement and the machine data are shown. After a short introduction to the winding function and multiple circuit theory the calculation of the self- and mutual- inductances based on its Fourier series is explained. Moreover the difference between using a rectangular and a trapezoidal characteristic of the winding function is described. Especially for this type of machine the needed assumptions and simplifications are presented as well. In a next step the simulation model implemented in Matlab/Simulink is presented. The paper ends with some simulation results compared to the machine data and a short conclusion.","PeriodicalId":243822,"journal":{"name":"2012 Electrical Systems for Aircraft, Railway and Ship Propulsion","volume":"32 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123538493","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 : 2012-12-24DOI: 10.1109/ESARS.2012.6387477
K. Boudjit, W. Korzet, A. Nacer, H. Moulai, C. Larbes
Power grids are actually more complex in their structure and in the requirements that they must satisfy, including perfect sinusoidal wave without outages and transitory over-voltages. Among the faults that can occur in the distribution networks, high impedance and arc faults are the most persistent and difficult to solve. Recent advances in digital technology have enabled practical solutions for fast detection of a high percentage of these previously undetectable faults. In this paper, a new approach for high impedance arc faults detection is presented. It is possible, by using a Digital Signal processor (DSP), to conceive a system able to detect the presence of unwanted and alarming frequencies in the distribution network. These particular frequencies are generated by electrical arcs occurring in the network. Finally, experimental and simulation results are provided to validate the performance of the digital implementation.
{"title":"DSP use in distribution power grids - A new approach for high impedance ARC faults detection","authors":"K. Boudjit, W. Korzet, A. Nacer, H. Moulai, C. Larbes","doi":"10.1109/ESARS.2012.6387477","DOIUrl":"https://doi.org/10.1109/ESARS.2012.6387477","url":null,"abstract":"Power grids are actually more complex in their structure and in the requirements that they must satisfy, including perfect sinusoidal wave without outages and transitory over-voltages. Among the faults that can occur in the distribution networks, high impedance and arc faults are the most persistent and difficult to solve. Recent advances in digital technology have enabled practical solutions for fast detection of a high percentage of these previously undetectable faults. In this paper, a new approach for high impedance arc faults detection is presented. It is possible, by using a Digital Signal processor (DSP), to conceive a system able to detect the presence of unwanted and alarming frequencies in the distribution network. These particular frequencies are generated by electrical arcs occurring in the network. Finally, experimental and simulation results are provided to validate the performance of the digital implementation.","PeriodicalId":243822,"journal":{"name":"2012 Electrical Systems for Aircraft, Railway and Ship Propulsion","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127892962","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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