Pub Date : 2002-12-10DOI: 10.1109/IAS.2002.1044060
C. Kuert, M. Jufer, Y. Perriard
To be able to calculate the performances of a hybrid stepping motor or to design it in a short time, it is essential to apply an efficient model, accepting a slight loss of precision. Using software based on finite elements and executing calculations are difficult and time consuming, but normally offers increased precision. Finite elements may be used to better understand some phenomena and help establishing an analytic modeling based on magnetic equivalent scheme. Torque calculation is therefore much faster and permits to easily optimize a given structure. The dynamic modeling permits an estimation of dynamic behavior of the hybrid stepping motor in stationary and transient states.
{"title":"New method for dynamic modeling of hybrid stepping motors","authors":"C. Kuert, M. Jufer, Y. Perriard","doi":"10.1109/IAS.2002.1044060","DOIUrl":"https://doi.org/10.1109/IAS.2002.1044060","url":null,"abstract":"To be able to calculate the performances of a hybrid stepping motor or to design it in a short time, it is essential to apply an efficient model, accepting a slight loss of precision. Using software based on finite elements and executing calculations are difficult and time consuming, but normally offers increased precision. Finite elements may be used to better understand some phenomena and help establishing an analytic modeling based on magnetic equivalent scheme. Torque calculation is therefore much faster and permits to easily optimize a given structure. The dynamic modeling permits an estimation of dynamic behavior of the hybrid stepping motor in stationary and transient states.","PeriodicalId":202482,"journal":{"name":"Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344)","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123119295","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 : 2002-12-10DOI: 10.1109/IAS.2002.1042811
J. J. Nelson, G. Venkataramanan, B. Beihoff
Widespread application of IGBTs in the past decade has resulted in dramatic improvement in performance of power electronic converters, with simultaneous reduction in costs. In order to further reduce the cost of power electronics systems and improve their reliability it is imperative that techniques for standardized and integrated architectures be adopted, allowing them to be mass-customized for a larger class of applications. One of the key factors that allow broad application of a power switching devices rated at a lower power level across large power levels is ease of parallel operation. This paper is devoted to presenting the results from investigation of parallel operation of IGBT devices. Experimental and computer simulation results are presented.
{"title":"Investigation of parallel operation of IGBTs","authors":"J. J. Nelson, G. Venkataramanan, B. Beihoff","doi":"10.1109/IAS.2002.1042811","DOIUrl":"https://doi.org/10.1109/IAS.2002.1042811","url":null,"abstract":"Widespread application of IGBTs in the past decade has resulted in dramatic improvement in performance of power electronic converters, with simultaneous reduction in costs. In order to further reduce the cost of power electronics systems and improve their reliability it is imperative that techniques for standardized and integrated architectures be adopted, allowing them to be mass-customized for a larger class of applications. One of the key factors that allow broad application of a power switching devices rated at a lower power level across large power levels is ease of parallel operation. This paper is devoted to presenting the results from investigation of parallel operation of IGBT devices. Experimental and computer simulation results are presented.","PeriodicalId":202482,"journal":{"name":"Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344)","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117129736","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 : 2002-12-10DOI: 10.1109/IAS.2002.1042698
D. Vilathgamuwa, H. M. Wijekoon
Highly automated production processes are particularly susceptible to voltage disturbances in the power system. Series compensation in the form of dynamic voltage restorer (DVR) is used to mitigate these voltage disturbances. The compensation capability of a particular DVR topology depends on its voltage injection ability and maximum energy storage. This paper presents a new DVR circuit topology which has the ability to mitigate long duration voltage sags with comparatively small energy storage capacitors. The proposed DVR is equipped with a line-side current forced reversible rectifier that helps to maintain the DC-link voltage under voltage sag conditions. A closed loop controller that consists of an inner current loop and an outer voltage loop has been incorporated into the DVR inverter to maintain the load voltage at a desired level. Simulation and experimental results are presented to demonstrate the efficacy of proposed DVR multiloop controller for various voltage sags.
{"title":"Control and analysis of a new dynamic voltage restorer circuit topology for mitigating long duration voltage sags","authors":"D. Vilathgamuwa, H. M. Wijekoon","doi":"10.1109/IAS.2002.1042698","DOIUrl":"https://doi.org/10.1109/IAS.2002.1042698","url":null,"abstract":"Highly automated production processes are particularly susceptible to voltage disturbances in the power system. Series compensation in the form of dynamic voltage restorer (DVR) is used to mitigate these voltage disturbances. The compensation capability of a particular DVR topology depends on its voltage injection ability and maximum energy storage. This paper presents a new DVR circuit topology which has the ability to mitigate long duration voltage sags with comparatively small energy storage capacitors. The proposed DVR is equipped with a line-side current forced reversible rectifier that helps to maintain the DC-link voltage under voltage sag conditions. A closed loop controller that consists of an inner current loop and an outer voltage loop has been incorporated into the DVR inverter to maintain the load voltage at a desired level. Simulation and experimental results are presented to demonstrate the efficacy of proposed DVR multiloop controller for various voltage sags.","PeriodicalId":202482,"journal":{"name":"Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121060072","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 : 2002-12-10DOI: 10.1109/PAPCON.2003.1216900
P. Pillai, A. Pierce, B. Bailey, B. Douglas, C. Mozina, C. Normand, D. Love, D. Shipp, G. Dalke, J.R. Jones, J. Fischer, J. Bowen, L. Padden, L. Powell, N. Nichols, R. Young, N. Stringer
The paper discusses typical grounding practices and ground fault protection methods for medium voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. These topics are presented in four separate papers. Part 1 covers scope, introduction, user examples of stator ground failure, and theoretical basis for the problem.
{"title":"Grounding and ground fault protection of multiple generator installations on medium-voltage industrial and commercial power systems. I. The problem defined","authors":"P. Pillai, A. Pierce, B. Bailey, B. Douglas, C. Mozina, C. Normand, D. Love, D. Shipp, G. Dalke, J.R. Jones, J. Fischer, J. Bowen, L. Padden, L. Powell, N. Nichols, R. Young, N. Stringer","doi":"10.1109/PAPCON.2003.1216900","DOIUrl":"https://doi.org/10.1109/PAPCON.2003.1216900","url":null,"abstract":"The paper discusses typical grounding practices and ground fault protection methods for medium voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. These topics are presented in four separate papers. Part 1 covers scope, introduction, user examples of stator ground failure, and theoretical basis for the problem.","PeriodicalId":202482,"journal":{"name":"Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124922790","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 : 2002-12-10DOI: 10.1109/IAS.2002.1043772
M. Prieto, A. Pernía, J. Lopera, J.A. Martin, F. Nuño
Driven by the need to reduce the size and weight of power converters, there have been several attempts to provide a structural integration of inductors and transformers. However, most of them are focused on the MHz-range handling very low currents. A recent work has proven the suitability of thick-film technology to produce power inductors, but the design suggested did not provide turn-coupling in the structure. The present paper builds on the results of the above mentioned work indicating new conductor arrangements that allow obtaining turn coupling in thick-film magnetic structures. The benefit of having such a coupling is twofold. On the one hand, it allows integrating inductors in even smaller volumes. On the other hand, it makes it possible to design flat power transformers using this integration technique. A complete design procedure of both, power inductors with turn-coupling and power transformers, is presented in this paper. A full characterization of these thick-film transformers is also given. Some experimental results are included as well so that the reader can validate the modeling proposed.
{"title":"Turn-coupling in thick-film integrated magnetic components for power converters","authors":"M. Prieto, A. Pernía, J. Lopera, J.A. Martin, F. Nuño","doi":"10.1109/IAS.2002.1043772","DOIUrl":"https://doi.org/10.1109/IAS.2002.1043772","url":null,"abstract":"Driven by the need to reduce the size and weight of power converters, there have been several attempts to provide a structural integration of inductors and transformers. However, most of them are focused on the MHz-range handling very low currents. A recent work has proven the suitability of thick-film technology to produce power inductors, but the design suggested did not provide turn-coupling in the structure. The present paper builds on the results of the above mentioned work indicating new conductor arrangements that allow obtaining turn coupling in thick-film magnetic structures. The benefit of having such a coupling is twofold. On the one hand, it allows integrating inductors in even smaller volumes. On the other hand, it makes it possible to design flat power transformers using this integration technique. A complete design procedure of both, power inductors with turn-coupling and power transformers, is presented in this paper. A full characterization of these thick-film transformers is also given. Some experimental results are included as well so that the reader can validate the modeling proposed.","PeriodicalId":202482,"journal":{"name":"Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125972320","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 : 2002-12-10DOI: 10.1109/IAS.2002.1044123
Jun-Koo Kang, H. Hara, E. Yamamoto, E. Watanabe
The matrix converter (MC) is a bidirectional AC/AC conversion device that generates variable-voltage variable-frequency output from ac voltage utility. Since power topology and switching rules of MC are quite different from voltage source inverter (VSI), power device loss analysis based on VSI topology cannot be applied to MC. In this paper, analysis method for evaluation of bidirectional switch losses of MC is proposed. Variation of collector-emitter voltage and current distribution in bidirectional IGBTs are investigated at various operating conditions for power loss analysis. The validity of the proposed analysis has been verified through the simulations and the experimental results with 7.5 kW MC driven-AC drives system.
矩阵变换器(MC)是一种双向交流/交流转换装置，它从交流电压公用事业产生可变电压变频输出。由于MC的功率拓扑和开关规则与电压源逆变器(VSI)有很大的不同，基于VSI拓扑的功率器件损耗分析无法应用于MC。本文提出了MC双向开关损耗评估的分析方法。研究了双向igbt在不同工作条件下集电极-发射极电压和电流分布的变化规律，用于功率损耗分析。通过7.5 kW MC - ac驱动系统的仿真和实验结果验证了分析的有效性。
{"title":"Analysis and evaluation of bi-directional power switch losses for matrix converter drive","authors":"Jun-Koo Kang, H. Hara, E. Yamamoto, E. Watanabe","doi":"10.1109/IAS.2002.1044123","DOIUrl":"https://doi.org/10.1109/IAS.2002.1044123","url":null,"abstract":"The matrix converter (MC) is a bidirectional AC/AC conversion device that generates variable-voltage variable-frequency output from ac voltage utility. Since power topology and switching rules of MC are quite different from voltage source inverter (VSI), power device loss analysis based on VSI topology cannot be applied to MC. In this paper, analysis method for evaluation of bidirectional switch losses of MC is proposed. Variation of collector-emitter voltage and current distribution in bidirectional IGBTs are investigated at various operating conditions for power loss analysis. The validity of the proposed analysis has been verified through the simulations and the experimental results with 7.5 kW MC driven-AC drives system.","PeriodicalId":202482,"journal":{"name":"Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115053406","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 : 2002-12-10DOI: 10.1109/IAS.2002.1042699
Rong Zheng, Jinliang He, J. Zou, Xinfu Sheng
A scientific design method was introduced to decrease the grounding resistances of two 110 kV urban substations' grounding systems in this paper. The first step of the grounding system design process is to gain the soil structure, and the second step is to design the grounding system by numerical analysis according to the multi-layer soil structure model. The peripheral geographical conditions have been taken into consideration to effectively decrease the grounding resistances of substation's grounding system.
{"title":"Novel method in decreasing grounding resistances of urban substations by utilizing peripheral geographical conditions","authors":"Rong Zheng, Jinliang He, J. Zou, Xinfu Sheng","doi":"10.1109/IAS.2002.1042699","DOIUrl":"https://doi.org/10.1109/IAS.2002.1042699","url":null,"abstract":"A scientific design method was introduced to decrease the grounding resistances of two 110 kV urban substations' grounding systems in this paper. The first step of the grounding system design process is to gain the soil structure, and the second step is to design the grounding system by numerical analysis according to the multi-layer soil structure model. The peripheral geographical conditions have been taken into consideration to effectively decrease the grounding resistances of substation's grounding system.","PeriodicalId":202482,"journal":{"name":"Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344)","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114143049","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 : 2002-12-10DOI: 10.1109/IAS.2002.1042732
Young-Deok Choi, Dong-Yun Lee, D. Hyun
In this paper, a new control scheme of Class-E inverter for induction heating (IH) jar applications with clamped voltage characteristics using pulse-frequency modulation (PFM) is introduced. To reduce the voltage stress of the switch, the proposed PFM control scheme doesn't need any auxiliary circuit in comparison to a family of active clamped Class E (ACCE) inverter. It can decrease voltage stress of switch through modulation of switching frequency. The Class-E inverter using the proposed control scheme has the advantages of not only the same output power when it is compared with a hybrid-active clamped Class-E (hybrid-ACCE) inverter but also zero-voltage-switching (ZVS), which are characteristics of conventional Class-E and active clamped Class-E (ACCE) inverter. The control principles of the proposed method are explained in detail and its validity is verified through experimental results.
{"title":"A study on the new control scheme of Class-E inverter for IH-jar application with clamped voltage characteristics using pulse frequency modulation","authors":"Young-Deok Choi, Dong-Yun Lee, D. Hyun","doi":"10.1109/IAS.2002.1042732","DOIUrl":"https://doi.org/10.1109/IAS.2002.1042732","url":null,"abstract":"In this paper, a new control scheme of Class-E inverter for induction heating (IH) jar applications with clamped voltage characteristics using pulse-frequency modulation (PFM) is introduced. To reduce the voltage stress of the switch, the proposed PFM control scheme doesn't need any auxiliary circuit in comparison to a family of active clamped Class E (ACCE) inverter. It can decrease voltage stress of switch through modulation of switching frequency. The Class-E inverter using the proposed control scheme has the advantages of not only the same output power when it is compared with a hybrid-active clamped Class-E (hybrid-ACCE) inverter but also zero-voltage-switching (ZVS), which are characteristics of conventional Class-E and active clamped Class-E (ACCE) inverter. The control principles of the proposed method are explained in detail and its validity is verified through experimental results.","PeriodicalId":202482,"journal":{"name":"Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344)","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121912969","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 : 2002-12-10DOI: 10.1109/IAS.2002.1043751
S. E. Schulz, Khwaja M. Rahman
This paper presents a design methodology for digital PI current regulators that may be used for the highly nonlinear switched reluctance motor control. The important nonlinear behavior of saturation, back EMF, and mutual coupling are accounted for to achieve consistent current regulator performance over the entire operating regime. Gain adaptation is used with respect to both position and current to ensure stability. An improved back EMF decoupling scheme is implemented to reduce bandwidth requirements. The proposed control is implemented on a high torque traction drive for EV applications. Simulation and experimental results demonstrate excellent performance over the entire operating regime.
{"title":"High performance digital PI current regulator for EV switched reluctance motor drives","authors":"S. E. Schulz, Khwaja M. Rahman","doi":"10.1109/IAS.2002.1043751","DOIUrl":"https://doi.org/10.1109/IAS.2002.1043751","url":null,"abstract":"This paper presents a design methodology for digital PI current regulators that may be used for the highly nonlinear switched reluctance motor control. The important nonlinear behavior of saturation, back EMF, and mutual coupling are accounted for to achieve consistent current regulator performance over the entire operating regime. Gain adaptation is used with respect to both position and current to ensure stability. An improved back EMF decoupling scheme is implemented to reduce bandwidth requirements. The proposed control is implemented on a high torque traction drive for EV applications. Simulation and experimental results demonstrate excellent performance over the entire operating regime.","PeriodicalId":202482,"journal":{"name":"Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122232174","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 : 2002-12-10DOI: 10.1109/IAS.2002.1043823
K. Mino, S. Igarashi, K. Kazuo
This paper describes an AC-DC converter using a universal input voltage type three-phase power factor correction (PFC) circuit and phase-shifted zero voltage switching (ZVS) DC-DC converters. The AC-DC converter has features of low impressed voltage on the semiconductors, high frequency operation, and high efficiency, which are confirmed through experiments. Moreover, the PFC circuit is capable of controlling the voltages of two output capacitors connected in series, individually. The ZVS DC-DC converters, on the other hand, reduce the output voltage ripple at the switching transient with the phase-shifted control. The efficiency of the AC-DC converter is improved 1.3% higher than that of our conventional products.
{"title":"A three-phase AC-DC converter using universal input voltage type PFC circuit and phase-shift controlled DC-DC converters","authors":"K. Mino, S. Igarashi, K. Kazuo","doi":"10.1109/IAS.2002.1043823","DOIUrl":"https://doi.org/10.1109/IAS.2002.1043823","url":null,"abstract":"This paper describes an AC-DC converter using a universal input voltage type three-phase power factor correction (PFC) circuit and phase-shifted zero voltage switching (ZVS) DC-DC converters. The AC-DC converter has features of low impressed voltage on the semiconductors, high frequency operation, and high efficiency, which are confirmed through experiments. Moreover, the PFC circuit is capable of controlling the voltages of two output capacitors connected in series, individually. The ZVS DC-DC converters, on the other hand, reduce the output voltage ripple at the switching transient with the phase-shifted control. The efficiency of the AC-DC converter is improved 1.3% higher than that of our conventional products.","PeriodicalId":202482,"journal":{"name":"Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344)","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116749350","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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