Pub Date : 2008-03-12DOI: 10.1109/MEPCON.2008.4562319
M. El-Saadawi, M. Tantawy, A. Hatata
Harmonics is one of the major disturbances that affect the power quality of electric utilities. Many techniques were used to analyze the harmonics in power systems. These techniques generally have difficulties in determining the collective impact of distributed harmonic sources. This paper introduces a proposed methodology for analyzing harmonics in distribution systems with distributed harmonic sources. The method takes into account the effect of diversity and attenuation. The method is illustrated through a numerical application applied on a real distributor.
{"title":"A proposed methodology to analyze systems with distributed harmonic sources","authors":"M. El-Saadawi, M. Tantawy, A. Hatata","doi":"10.1109/MEPCON.2008.4562319","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562319","url":null,"abstract":"Harmonics is one of the major disturbances that affect the power quality of electric utilities. Many techniques were used to analyze the harmonics in power systems. These techniques generally have difficulties in determining the collective impact of distributed harmonic sources. This paper introduces a proposed methodology for analyzing harmonics in distribution systems with distributed harmonic sources. The method takes into account the effect of diversity and attenuation. The method is illustrated through a numerical application applied on a real distributor.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130429126","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562392
Adel Ali, A. El-Ela, R. El-Sehiemy, O. Ahmed
This paper proposes modified distribution factors (MDF) for computing the transmission power flows in terms of power generation outputs. The proposed MDF are capable for obtaining higher quality solutions for different power system problems. A modified particle swarm optimization (MPSO) version is proposed to solve the power dispatch problem. Comparison studies based on the optimal generation payment model are performed to show the superiority of the proposed MDF and MPSO compared to the existed methods. In the competitive environment, the use of the proposed distribution factors leads to fair allocation of users' responsibilities in recovery problems such as loss allocation and transmission usage allocation. Added to that, the use of the MPSO leads to competitive generation costs.
{"title":"Optimized generation costs using a modified particle swarm optimization version","authors":"Adel Ali, A. El-Ela, R. El-Sehiemy, O. Ahmed","doi":"10.1109/MEPCON.2008.4562392","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562392","url":null,"abstract":"This paper proposes modified distribution factors (MDF) for computing the transmission power flows in terms of power generation outputs. The proposed MDF are capable for obtaining higher quality solutions for different power system problems. A modified particle swarm optimization (MPSO) version is proposed to solve the power dispatch problem. Comparison studies based on the optimal generation payment model are performed to show the superiority of the proposed MDF and MPSO compared to the existed methods. In the competitive environment, the use of the proposed distribution factors leads to fair allocation of users' responsibilities in recovery problems such as loss allocation and transmission usage allocation. Added to that, the use of the MPSO leads to competitive generation costs.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115131495","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562383
H. Kojima, N. Hayakawa, F. Endo, H. Okubo
An understanding of mechanism of partial discharge (PD) in SF6 gas is critical for diagnosis of PD in electric power equipment and contributes to the optimization of the design of electric power applications. However, for complexity of PD characteristics under non-uniform electric field, the mechanism of PD in SF6 is not comprehended enough. For this reason, we aim to reveal the PD mechanism by measuring current waveform, propagation characteristics and light emission of PD in SF6 gas and analyzing these data. For this purpose, we have developed excellent measurement and analysis techniques. For an analysis of PD under ac voltage application, not only PD waveforms but also PD propagation property is essential. We have constructed partial discharge current pulse waveform analysis (PD-CPWA) system. This system has enabled us to observe PD current sequentially at high speed and analyze the propagation of PD current pulse statistically. By the application of PD-CPWA system to diagnosis of PD activity due to the metallic particle in SF6, we could identify the particle type and size. On the other hand, for an analysis of PD under impulse voltage application, an ultra high-speed PD measurement by various methods is extremely important. In order to investigate the impulse PD mechanism spatially and temporally, the simultaneous measurement of current and light emission intensity waveforms, streak and still light emission images and temporal evolution of spectrum of PD light emission have been carried out. By using this synchronous ultra-high speed PD measurement system, we revealed the change of light emission from decomposition products depending on the step propagation of leader discharge.
{"title":"Novel measurement and analysis system for investigation of partial discharge mechanism in SF6 Gas","authors":"H. Kojima, N. Hayakawa, F. Endo, H. Okubo","doi":"10.1109/MEPCON.2008.4562383","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562383","url":null,"abstract":"An understanding of mechanism of partial discharge (PD) in SF6 gas is critical for diagnosis of PD in electric power equipment and contributes to the optimization of the design of electric power applications. However, for complexity of PD characteristics under non-uniform electric field, the mechanism of PD in SF6 is not comprehended enough. For this reason, we aim to reveal the PD mechanism by measuring current waveform, propagation characteristics and light emission of PD in SF6 gas and analyzing these data. For this purpose, we have developed excellent measurement and analysis techniques. For an analysis of PD under ac voltage application, not only PD waveforms but also PD propagation property is essential. We have constructed partial discharge current pulse waveform analysis (PD-CPWA) system. This system has enabled us to observe PD current sequentially at high speed and analyze the propagation of PD current pulse statistically. By the application of PD-CPWA system to diagnosis of PD activity due to the metallic particle in SF6, we could identify the particle type and size. On the other hand, for an analysis of PD under impulse voltage application, an ultra high-speed PD measurement by various methods is extremely important. In order to investigate the impulse PD mechanism spatially and temporally, the simultaneous measurement of current and light emission intensity waveforms, streak and still light emission images and temporal evolution of spectrum of PD light emission have been carried out. By using this synchronous ultra-high speed PD measurement system, we revealed the change of light emission from decomposition products depending on the step propagation of leader discharge.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"93 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124666445","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562311
M. Alkuran, M. Orabi
A novel method for making Capacitive Deionization (CDI) water purification more efficient and cheaper using a buck- boost DC/DC converter is presented in this paper. The energy recovery is superior (51%) versus maximum reported results in the literature (30%) [1]. First, the concept of a CDI cell is introduced. Second, the existing methods for energy recovery are reported showing their advantages and disadvantages. Then, the novel method using a buck-boost converter is presented. Also, the method of segmented capacitors is presented. Simulation results are provided. Experimental data verified the new technique and agrees with simulation.
{"title":"Utilization of a buck boost converter and the method of segmented capacitors in a CDI water purification system","authors":"M. Alkuran, M. Orabi","doi":"10.1109/MEPCON.2008.4562311","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562311","url":null,"abstract":"A novel method for making Capacitive Deionization (CDI) water purification more efficient and cheaper using a buck- boost DC/DC converter is presented in this paper. The energy recovery is superior (51%) versus maximum reported results in the literature (30%) [1]. First, the concept of a CDI cell is introduced. Second, the existing methods for energy recovery are reported showing their advantages and disadvantages. Then, the novel method using a buck-boost converter is presented. Also, the method of segmented capacitors is presented. Simulation results are provided. Experimental data verified the new technique and agrees with simulation.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130691293","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562360
A. Hoballah, I. Erlich
This paper presents a security constrained power system dynamic performance enhancement using particle swarm optimization (PSO) based on time domain simulation (TDS). The key feature of the security monitoring is the critical fault clearing time. Time-domain simulation is used to determine the unstable point of the power system based on bisection technique to reduce computation time. The Independent System Operator (ISO) should plan hours-ahead or days-ahead rescheduling to determine the optimal allocation of generated power from each generator based on the expected system disturbances. The objective is to find proper adjustments of the generated power that maintain acceptable security levels throughout the system and minimize system losses. The generation rescheduling (GR) is considered as a necessary remedial action to improve the system transient stability during the disturbances. PSO is used to determine the most suitable generation coordination among system generators.
{"title":"Generation coordination for transient stability enhancement using particle swarm optimization","authors":"A. Hoballah, I. Erlich","doi":"10.1109/MEPCON.2008.4562360","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562360","url":null,"abstract":"This paper presents a security constrained power system dynamic performance enhancement using particle swarm optimization (PSO) based on time domain simulation (TDS). The key feature of the security monitoring is the critical fault clearing time. Time-domain simulation is used to determine the unstable point of the power system based on bisection technique to reduce computation time. The Independent System Operator (ISO) should plan hours-ahead or days-ahead rescheduling to determine the optimal allocation of generated power from each generator based on the expected system disturbances. The objective is to find proper adjustments of the generated power that maintain acceptable security levels throughout the system and minimize system losses. The generation rescheduling (GR) is considered as a necessary remedial action to improve the system transient stability during the disturbances. PSO is used to determine the most suitable generation coordination among system generators.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"36 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114112156","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562352
T. Kawady, N. Mansour, A. Osheiba, A. Taalab
This paper provides the basic outlines of dynamic modeling of Al-Zaafarana wind farm as a typical example for large wind farm simulation for protection applications. MATLAB "the most known simulation Package" is employed for this target. The package represents an ideal candidate for dynamic simulation purposes with its own highly performance graphical interface and built-in libraries. All abnormal operating conditions including load variations, short circuits, and wind speed variations are considered. This gives a better understanding of the overall performance of wind farms during fault circumstances as well as provides a sufficient platform for investigating conventional and non-conventional protection equipment for wind farms.
{"title":"Dynamic modeling of Al-Zaafarana wind farm for protection applications","authors":"T. Kawady, N. Mansour, A. Osheiba, A. Taalab","doi":"10.1109/MEPCON.2008.4562352","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562352","url":null,"abstract":"This paper provides the basic outlines of dynamic modeling of Al-Zaafarana wind farm as a typical example for large wind farm simulation for protection applications. MATLAB \"the most known simulation Package\" is employed for this target. The package represents an ideal candidate for dynamic simulation purposes with its own highly performance graphical interface and built-in libraries. All abnormal operating conditions including load variations, short circuits, and wind speed variations are considered. This gives a better understanding of the overall performance of wind farms during fault circumstances as well as provides a sufficient platform for investigating conventional and non-conventional protection equipment for wind farms.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121509161","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562347
M. Abdel-Akher, K. M. Nor, A. Abdul-Rashid
This paper presents a new power-flow method for analyzing unbalanced distribution networks. In this method, an unbalanced distribution network Is decomposed to: 1) main three-phase network with three-phase line segments and 2) unbalanced laterals with two-phase and single-phase line segments. The proposed method allows solving the main three-phase network based on the decoupled positive-, negative, and zero-sequence networks. The unbalanced laterals are solved using the forward/backward method In phase components. The solution process Involves three main steps. Firstly, In phase components, the backward step Is executed to calculate an equivalent current Injection for each unbalanced lateral. Secondly, the main three-phase network Is solved In sequence components. The standard Newton-Raphson and fast decoupled methods are used for solving the positive-sequence network whereas the negative- and zero-sequence networks are represented by two nodal voltage equations. Finally, In phase components, the forward step Is performed to update the voltages In the unbalanced laterals. The three-steps are repeated till convergence happen. Distribution network characteristics such as line coupling, transformer phase shifts, voltage regulators, PV nodes, capacitor banks, and spot or distributed loads with any type and connection are considered. Solution of unbalanced radial feeders shows that the proposed hybrid algorithm Is accurate.
{"title":"Development of unbalanced three-phase distribution power flow analysis using sequence and phase components","authors":"M. Abdel-Akher, K. M. Nor, A. Abdul-Rashid","doi":"10.1109/MEPCON.2008.4562347","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562347","url":null,"abstract":"This paper presents a new power-flow method for analyzing unbalanced distribution networks. In this method, an unbalanced distribution network Is decomposed to: 1) main three-phase network with three-phase line segments and 2) unbalanced laterals with two-phase and single-phase line segments. The proposed method allows solving the main three-phase network based on the decoupled positive-, negative, and zero-sequence networks. The unbalanced laterals are solved using the forward/backward method In phase components. The solution process Involves three main steps. Firstly, In phase components, the backward step Is executed to calculate an equivalent current Injection for each unbalanced lateral. Secondly, the main three-phase network Is solved In sequence components. The standard Newton-Raphson and fast decoupled methods are used for solving the positive-sequence network whereas the negative- and zero-sequence networks are represented by two nodal voltage equations. Finally, In phase components, the forward step Is performed to update the voltages In the unbalanced laterals. The three-steps are repeated till convergence happen. Distribution network characteristics such as line coupling, transformer phase shifts, voltage regulators, PV nodes, capacitor banks, and spot or distributed loads with any type and connection are considered. Solution of unbalanced radial feeders shows that the proposed hybrid algorithm Is accurate.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117218868","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562403
A. Alkandari, S. Soliman, A.H. Mantwy
This paper introduces new applications to Simulated Annealing (SA) optimization algorithm for measuring the voltage flicker magnitude and frequency as well as the harmonics contents of the voltage signal, for power quality analysis Moreover, the power system voltage magnitude, frequency and phase angle of the fundamental component is estimated by the proposed technique. This is a nonlinear optimization problem in continuous variables. An efficient SA algorithm with an adaptive cooling schedule and a new method for variable discretization are implemented. The new algorithm minimizes the sum of the absolute value of the error in the estimated voltage signal, and does need any approximation in modeling the voltage signal. The proposed algorithm is tested on simulated and actual recorded data. Effects of sampling frequency as well as the number of samples on the estimated parameters are discussed, ft is shown that the proposed algorithm is able to identify the parameters of the voltage signal.
{"title":"Simulated annealing optimization algorithm for electric power systems quality analysis: harmonics and voltage flickers","authors":"A. Alkandari, S. Soliman, A.H. Mantwy","doi":"10.1109/MEPCON.2008.4562403","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562403","url":null,"abstract":"This paper introduces new applications to Simulated Annealing (SA) optimization algorithm for measuring the voltage flicker magnitude and frequency as well as the harmonics contents of the voltage signal, for power quality analysis Moreover, the power system voltage magnitude, frequency and phase angle of the fundamental component is estimated by the proposed technique. This is a nonlinear optimization problem in continuous variables. An efficient SA algorithm with an adaptive cooling schedule and a new method for variable discretization are implemented. The new algorithm minimizes the sum of the absolute value of the error in the estimated voltage signal, and does need any approximation in modeling the voltage signal. The proposed algorithm is tested on simulated and actual recorded data. Effects of sampling frequency as well as the number of samples on the estimated parameters are discussed, ft is shown that the proposed algorithm is able to identify the parameters of the voltage signal.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"90 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120888050","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562358
Jin-Woo Jung, A. Keyhani
The paper presents a circuit model and controllers of fuel -cell -based distributed generation systems (DGS) in a standalone AC power supply. A dynamic model of the fuel cell is considered. To boost low -output DC voltage of the fuel cell to high DC voltage and to compensate for its slow response during the transient, two full-bridge DC-to-DC converters are adopted and their controllers are designed: a unidirectional full-bridge DC-to-DC boost converter for the fuel cell and a bidirectional full-bridge DC-to DC-buck/boost converter for the battery. For a three-phase DC-to-AC inverter, a discrete-time state space model in the stationary dq reference frame is derived, and two discrete-time-sliding mode controllers are designed: a voltage controller in the outer loop and a current controller in the inner loop.
{"title":"Fuel cell based distributed generation system","authors":"Jin-Woo Jung, A. Keyhani","doi":"10.1109/MEPCON.2008.4562358","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562358","url":null,"abstract":"The paper presents a circuit model and controllers of fuel -cell -based distributed generation systems (DGS) in a standalone AC power supply. A dynamic model of the fuel cell is considered. To boost low -output DC voltage of the fuel cell to high DC voltage and to compensate for its slow response during the transient, two full-bridge DC-to-DC converters are adopted and their controllers are designed: a unidirectional full-bridge DC-to-DC boost converter for the fuel cell and a bidirectional full-bridge DC-to DC-buck/boost converter for the battery. For a three-phase DC-to-AC inverter, a discrete-time state space model in the stationary dq reference frame is derived, and two discrete-time-sliding mode controllers are designed: a voltage controller in the outer loop and a current controller in the inner loop.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128884891","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 : 2008-03-12DOI: 10.1109/MEPCON.2008.4562364
Heungjae Lee, Kyeong-Seob Lee, Chanho Lim
This paper introduces an expert system to identify and correct a topology error in double-bus double-breaker substations. The proposed expert system has a topology based simple structure and it describes data required to represent the topology of substation such as switching devices and connection structures between devices. Also, the rule-base of this expert system composes basic rules suggested by KEPCO (Korean electric power company), including topology identification rules, topology error identification rules and heuristic rules. This expert system will be applied to Korean substation automation systems.
{"title":"Identification of topology error in double-bus double-breaker substations","authors":"Heungjae Lee, Kyeong-Seob Lee, Chanho Lim","doi":"10.1109/MEPCON.2008.4562364","DOIUrl":"https://doi.org/10.1109/MEPCON.2008.4562364","url":null,"abstract":"This paper introduces an expert system to identify and correct a topology error in double-bus double-breaker substations. The proposed expert system has a topology based simple structure and it describes data required to represent the topology of substation such as switching devices and connection structures between devices. Also, the rule-base of this expert system composes basic rules suggested by KEPCO (Korean electric power company), including topology identification rules, topology error identification rules and heuristic rules. This expert system will be applied to Korean substation automation systems.","PeriodicalId":236620,"journal":{"name":"2008 12th International Middle-East Power System Conference","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116321687","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：