Many fabric defects are very small and undistinguishable, which are very difficult to detect by only monitoring the intensity change. Faultless fabric is a repetitive and regular global texture and Fourier transform can be applied to monitor the spatial frequency spectrum of a fabric. When a defect occurs in fabric, its regular structure is changed so that the corresponding intensity at some specific positions of the frequency spectrum would change. However, the three-dimensional frequency spectrum is very difficult to analyze. In this paper, a simulated fabric model is used to understand the relationship between the fabric structure in the image space and in the frequency space. Based on the three-dimensional frequency spectrum, two significant spectrum diagrams are defined and used for analyzing the fabric defect. These two diagrams are called the central spatial frequency spectrums. The defects are broadly classified into four classes: (1) double yarn; (2) missing yarn; (3) webs or broken fabric; and (4) yarn densities variation. After evaluating these four classes of defects using some simulated models and real samples, seven characteristic parameters for central spatial frequency spectrum are extracted for defect classification.
{"title":"Fabric defect detection by Fourier analysis","authors":"Chi-Ho Chan, G. Pang","doi":"10.1109/IAS.1999.805975","DOIUrl":"https://doi.org/10.1109/IAS.1999.805975","url":null,"abstract":"Many fabric defects are very small and undistinguishable, which are very difficult to detect by only monitoring the intensity change. Faultless fabric is a repetitive and regular global texture and Fourier transform can be applied to monitor the spatial frequency spectrum of a fabric. When a defect occurs in fabric, its regular structure is changed so that the corresponding intensity at some specific positions of the frequency spectrum would change. However, the three-dimensional frequency spectrum is very difficult to analyze. In this paper, a simulated fabric model is used to understand the relationship between the fabric structure in the image space and in the frequency space. Based on the three-dimensional frequency spectrum, two significant spectrum diagrams are defined and used for analyzing the fabric defect. These two diagrams are called the central spatial frequency spectrums. The defects are broadly classified into four classes: (1) double yarn; (2) missing yarn; (3) webs or broken fabric; and (4) yarn densities variation. After evaluating these four classes of defects using some simulated models and real samples, seven characteristic parameters for central spatial frequency spectrum are extracted for defect classification.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128876135","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}
This paper addresses the problem of controlling the speed of a permanent magnet stepper motor assumed to operate in a high-performance drives environment. An artificial neural network control scheme which uses continual on-line random training (with no off-line training) to simultaneously identify and adaptively control the speed of the stepper motor is proposed. The control scheme utilizes two three-layer feed-forward artificial neural networks: (1) a tracker identification neural network which captures the nonlinear dynamics of the motor over any arbitrary time interval in its range of operation and (2) a controller neural network to provide the necessary control actions to achieve trajectory tracking of the motor speed. The inputs to the controller neural network are not constructed from the actual motor/load dynamics, but as a feedback signal, from the estimated state variables of the motor supplied by the neural identifier and the reference trajectory to be tracked by the actual speed. This paper also makes use of a very realistic and practical scheme to estimate and adaptively learn the noise content in the speed-load torque characteristic of the motor. Simulations reveal that the neuro-controller adapts and generalizes its learning rate to a wide variety of loads, in addition to providing the necessary abstraction when measurements are contaminated with noise.
{"title":"Adaptation learning control scheme for a high performance permanent magnet stepper motor using online random training of neural networks","authors":"A. Rubaai, R. Kotaru","doi":"10.1109/IAS.1999.799176","DOIUrl":"https://doi.org/10.1109/IAS.1999.799176","url":null,"abstract":"This paper addresses the problem of controlling the speed of a permanent magnet stepper motor assumed to operate in a high-performance drives environment. An artificial neural network control scheme which uses continual on-line random training (with no off-line training) to simultaneously identify and adaptively control the speed of the stepper motor is proposed. The control scheme utilizes two three-layer feed-forward artificial neural networks: (1) a tracker identification neural network which captures the nonlinear dynamics of the motor over any arbitrary time interval in its range of operation and (2) a controller neural network to provide the necessary control actions to achieve trajectory tracking of the motor speed. The inputs to the controller neural network are not constructed from the actual motor/load dynamics, but as a feedback signal, from the estimated state variables of the motor supplied by the neural identifier and the reference trajectory to be tracked by the actual speed. This paper also makes use of a very realistic and practical scheme to estimate and adaptively learn the noise content in the speed-load torque characteristic of the motor. Simulations reveal that the neuro-controller adapts and generalizes its learning rate to a wide variety of loads, in addition to providing the necessary abstraction when measurements are contaminated with noise.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"22 6S 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122813614","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}
An evaluation and comparison of a two-level conventional voltage source inverter (VSI) and an auxiliary resonant commutated pole voltage source inverter (ARCPVSI) featuring IGCTs for a 3 MVA application is presented. Design issues of both topologies are addressed. The IGCT loss approximations are based on extensive measurements of the devices under hard and soft switching conditions. The results show that the ARCPVSI with IGCTs is a highly competitive alternative to conventional VSIs in this power range.
{"title":"Evaluation of a high power ARCP voltage source inverter with IGCTs","authors":"S. Bernet, R. Teichmann, J. Weber, P. Steimer","doi":"10.1109/IAS.1999.801636","DOIUrl":"https://doi.org/10.1109/IAS.1999.801636","url":null,"abstract":"An evaluation and comparison of a two-level conventional voltage source inverter (VSI) and an auxiliary resonant commutated pole voltage source inverter (ARCPVSI) featuring IGCTs for a 3 MVA application is presented. Design issues of both topologies are addressed. The IGCT loss approximations are based on extensive measurements of the devices under hard and soft switching conditions. The results show that the ARCPVSI with IGCTs is a highly competitive alternative to conventional VSIs in this power range.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122833349","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}
The majority of rotor related faults in three-phase induction motors are due to broken bars and end rings. These faults occur primarily due to the thermal, magnetic, mechanical, environmental stresses that the rotor has to undergo during the routine usage. Faults involving several broken bars cause excessive vibration, noise and sparking during motor starting. Fabricated type rotors have more incidents of rotor bar and end ring breakage than cast rotors. On the other hand, cast rotors are more difficult to repair once they fail. Once a bar breaks; the condition of the neighboring bars also deteriorates progressively due to increased stresses. To prevent such a cumulative destructive process, the problem should be detected early, that is, when the bars are beginning to crack. This condition can be visualized as continuous increase in rotor bar resistance which increases from its nominal value to infinity when the bar is fully broken. Any experimental study to diagnose broken bar faults is costly as it causes irreversible damage to the rotor. Thus, a model based approach to simulate broken bar related faults at various degrees of severity is indeed essential. The present paper evaluates through simulation the line current spectrum of an induction motor at the incipient stage of bar breakage. The model can also be extended to multiple, full blown broken bar case. The speed and torque ripples caused by broken bars can also be studied. The rules and laws generated through such simulations can then be used in neural network based diagnostic tools. Results in case of complete broken bars are validated by finite element calculations. Experimental results with up to four bars partially broken with machine operating from balanced sinusoidal and inverter fed supply are presented. Simulation results showing that certain abnormal power supply conditions can produce broken bar like spectrum have also been included.
{"title":"Study of three phase induction motors with incipient rotor cage faults under different supply conditions","authors":"S. Nandi, R. Bharadwaj, H. Toliyat, A. Parlos","doi":"10.1109/IAS.1999.806001","DOIUrl":"https://doi.org/10.1109/IAS.1999.806001","url":null,"abstract":"The majority of rotor related faults in three-phase induction motors are due to broken bars and end rings. These faults occur primarily due to the thermal, magnetic, mechanical, environmental stresses that the rotor has to undergo during the routine usage. Faults involving several broken bars cause excessive vibration, noise and sparking during motor starting. Fabricated type rotors have more incidents of rotor bar and end ring breakage than cast rotors. On the other hand, cast rotors are more difficult to repair once they fail. Once a bar breaks; the condition of the neighboring bars also deteriorates progressively due to increased stresses. To prevent such a cumulative destructive process, the problem should be detected early, that is, when the bars are beginning to crack. This condition can be visualized as continuous increase in rotor bar resistance which increases from its nominal value to infinity when the bar is fully broken. Any experimental study to diagnose broken bar faults is costly as it causes irreversible damage to the rotor. Thus, a model based approach to simulate broken bar related faults at various degrees of severity is indeed essential. The present paper evaluates through simulation the line current spectrum of an induction motor at the incipient stage of bar breakage. The model can also be extended to multiple, full blown broken bar case. The speed and torque ripples caused by broken bars can also be studied. The rules and laws generated through such simulations can then be used in neural network based diagnostic tools. Results in case of complete broken bars are validated by finite element calculations. Experimental results with up to four bars partially broken with machine operating from balanced sinusoidal and inverter fed supply are presented. Simulation results showing that certain abnormal power supply conditions can produce broken bar like spectrum have also been included.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126404391","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}
This paper describes the analysis of the neutral point (mid-point) potential variation in the 3-level SVPWM converter and inverter, and proposes a mid-point current controller (MPCC). The variation of the mid-point potential is analyzed in detail with the focus on the current flowing out of or into the mid-point with the proposed SVPWM method. The authors show that the 3-level converter and inverter could be controlled to have no mid-point potential fluctuation by the MPCC. But, both the 3-level converter and inverter have the control limitation. In the converter/inverter pair system, however, the limitation could be overcome with the MPCC. The validity of the proposed method is demonstrated by the simulation results using Mablab/Simulink.
{"title":"A new neutral point current control for a 3-level converter/inverter pair system","authors":"Yo-han Lee, B. Suh, C. Choi, D. Hyun","doi":"10.1109/IAS.1999.805944","DOIUrl":"https://doi.org/10.1109/IAS.1999.805944","url":null,"abstract":"This paper describes the analysis of the neutral point (mid-point) potential variation in the 3-level SVPWM converter and inverter, and proposes a mid-point current controller (MPCC). The variation of the mid-point potential is analyzed in detail with the focus on the current flowing out of or into the mid-point with the proposed SVPWM method. The authors show that the 3-level converter and inverter could be controlled to have no mid-point potential fluctuation by the MPCC. But, both the 3-level converter and inverter have the control limitation. In the converter/inverter pair system, however, the limitation could be overcome with the MPCC. The validity of the proposed method is demonstrated by the simulation results using Mablab/Simulink.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126410673","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}
W. Brumsickle, G. Luckjiff, R. Schneider, D. Divan, M. McGranaghan
Voltage sags, transients, and momentary interruption of power together constitute 92% of the PQ problems encountered by typical industrial customers. The series-parallel connected dynamic sag corrector (DySC) provides statistically significant protection at greatly reduced cost. The DySC is rated 1.5 kVA 1-phase to 2000 kVA 3-phase and features a patented single stage power conversion circuit with minimal stored energy. A unique circuit allows operation with opened upstream circuit breaker. The paper presents a detailed discussion of DySC operating principles and validation of performance. It also provides conditions under which this new category of product can be applied.
{"title":"Dynamic sag correctors: cost effective industrial power line conditioning","authors":"W. Brumsickle, G. Luckjiff, R. Schneider, D. Divan, M. McGranaghan","doi":"10.1109/IAS.1999.801675","DOIUrl":"https://doi.org/10.1109/IAS.1999.801675","url":null,"abstract":"Voltage sags, transients, and momentary interruption of power together constitute 92% of the PQ problems encountered by typical industrial customers. The series-parallel connected dynamic sag corrector (DySC) provides statistically significant protection at greatly reduced cost. The DySC is rated 1.5 kVA 1-phase to 2000 kVA 3-phase and features a patented single stage power conversion circuit with minimal stored energy. A unique circuit allows operation with opened upstream circuit breaker. The paper presents a detailed discussion of DySC operating principles and validation of performance. It also provides conditions under which this new category of product can be applied.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127565039","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}
The paper presents the different measurement and identification approaches applied to a nonconventional PM synchronous machine: the novel axial flux interior permanent magnet (AFIPM) synchronous motor. The nonconventional geometry of the AFIPM motors requires a dedicated discussion on the parameters identification subject. In this paper, the standstill frequency response test and the standstill time response test on a AFIPM prototype are presented. On the basis of these tests, the d- and q-axis circuit parameters are chosen. To confirm the validity of the standstill tests, load tests have also been performed. Furthermore, the load tests provide some preliminary AFIPM machine performance results and additional information on the saturation phenomena. The d- and q-axis equivalent circuit parameters obtained by the performed measurements are analyzed and compared. Finally, the most appropriate AFIPM machine model is selected.
{"title":"Axial flux interior PM synchronous motor: parameters identification and steady-state performance measurements","authors":"A. Cavagnino, M. Lazzari, F. Profumo, A. Tenconi","doi":"10.1109/IAS.1999.799199","DOIUrl":"https://doi.org/10.1109/IAS.1999.799199","url":null,"abstract":"The paper presents the different measurement and identification approaches applied to a nonconventional PM synchronous machine: the novel axial flux interior permanent magnet (AFIPM) synchronous motor. The nonconventional geometry of the AFIPM motors requires a dedicated discussion on the parameters identification subject. In this paper, the standstill frequency response test and the standstill time response test on a AFIPM prototype are presented. On the basis of these tests, the d- and q-axis circuit parameters are chosen. To confirm the validity of the standstill tests, load tests have also been performed. Furthermore, the load tests provide some preliminary AFIPM machine performance results and additional information on the saturation phenomena. The d- and q-axis equivalent circuit parameters obtained by the performed measurements are analyzed and compared. Finally, the most appropriate AFIPM machine model is selected.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"117 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122852821","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}
The common mode voltage produced by the modulation of three-phase power inverters creates a significant amount of common mode conducted current in motor drives. As an alternative to inserting a large common mode choke to attenuate this common mode current, a modification to the inverter topology and the modulation strategy is proposed that can eliminate zero state components in the common mode voltage produced by the inverter. With the proposed modification, it is observed that the inverter generates substantially low common mode voltage, thereby resulting in the reduction of common mode current by several orders of magnitude. The topological structure, operating principles and performance characteristics are presented. A comparative evaluation of various alternatives studied in the literature to mitigate electromagnetic interference is also presented in the paper.
{"title":"An auxiliary zero state synthesizer to reduce common mode voltage in three-phase inverters","authors":"M. Manjrekar, T. Lipo","doi":"10.1109/IAS.1999.799924","DOIUrl":"https://doi.org/10.1109/IAS.1999.799924","url":null,"abstract":"The common mode voltage produced by the modulation of three-phase power inverters creates a significant amount of common mode conducted current in motor drives. As an alternative to inserting a large common mode choke to attenuate this common mode current, a modification to the inverter topology and the modulation strategy is proposed that can eliminate zero state components in the common mode voltage produced by the inverter. With the proposed modification, it is observed that the inverter generates substantially low common mode voltage, thereby resulting in the reduction of common mode current by several orders of magnitude. The topological structure, operating principles and performance characteristics are presented. A comparative evaluation of various alternatives studied in the literature to mitigate electromagnetic interference is also presented in the paper.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127857842","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 transient response of the voltage regulator module (VRM) output voltage when the processor has a sudden load change is analyzed. The parasitic parameters play important roles in the transient. The system can be divided into several resonant loops. Each loop can be considered approximately as a decoupled second order system. The voltage drop of the capacitor is analyzed. By reducing the inductance and increasing converter bandwidth, the transient of VRM can be improved.
{"title":"Voltage regulator module (VRM) transient modeling and analysis","authors":"P. Wong, F. Lee, Xunwei Zhou, Jiabin Chen","doi":"10.1109/IAS.1999.805965","DOIUrl":"https://doi.org/10.1109/IAS.1999.805965","url":null,"abstract":"In this paper, the transient response of the voltage regulator module (VRM) output voltage when the processor has a sudden load change is analyzed. The parasitic parameters play important roles in the transient. The system can be divided into several resonant loops. Each loop can be considered approximately as a decoupled second order system. The voltage drop of the capacitor is analyzed. By reducing the inductance and increasing converter bandwidth, the transient of VRM can be improved.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127794000","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}
Sibylle Dieckerhoff, Michael J. Ryan, R. W. D. Doncker
A power electronic inverter is developed for a high-frequency induction heating application. The application requires up to 160 kW of power at a frequency of 100 kHz. This power-frequency product represents a significant challenge for today's power semiconductor technology. Voltage source and current source inverters both using ZCS or ZVS are analyzed and compared. To attain the level of performance required, an LCL load-resonant topology is selected to enable ZVS close to the zero current crossing of the load. This mode of soft-switching is suitable to greatly reduce the IGBT losses. Inverter control is achieved via a phase locked loop (PLL). This paper presents the circuit design, modeling and control considerations.
{"title":"Design of an IGBT-based LCL-resonant inverter for high-frequency induction heating","authors":"Sibylle Dieckerhoff, Michael J. Ryan, R. W. D. Doncker","doi":"10.1109/IAS.1999.806017","DOIUrl":"https://doi.org/10.1109/IAS.1999.806017","url":null,"abstract":"A power electronic inverter is developed for a high-frequency induction heating application. The application requires up to 160 kW of power at a frequency of 100 kHz. This power-frequency product represents a significant challenge for today's power semiconductor technology. Voltage source and current source inverters both using ZCS or ZVS are analyzed and compared. To attain the level of performance required, an LCL load-resonant topology is selected to enable ZVS close to the zero current crossing of the load. This mode of soft-switching is suitable to greatly reduce the IGBT losses. Inverter control is achieved via a phase locked loop (PLL). This paper presents the circuit design, modeling and control considerations.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"277 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114078435","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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