A rectifier system having a voltage step-up and step-down characteristic is treated. The system consists of a three-phase PWM voltage source rectifier and a DC-to-DC buck converter connected in cascade. The linearized state equation which governs the whole system is presented. An optimal regulator is applied to control the rectifier system. The validity of the modeling and control strategy is confirmed by simulation studies.
{"title":"Modeling and control of PWM voltage source rectifier with a buck-boost characteristic in its output","authors":"S. Fukuda, T. Ito","doi":"10.1109/IAS.1999.798758","DOIUrl":"https://doi.org/10.1109/IAS.1999.798758","url":null,"abstract":"A rectifier system having a voltage step-up and step-down characteristic is treated. The system consists of a three-phase PWM voltage source rectifier and a DC-to-DC buck converter connected in cascade. The linearized state equation which governs the whole system is presented. An optimal regulator is applied to control the rectifier system. The validity of the modeling and control strategy is confirmed by simulation studies.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"197 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":"121835850","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 presents a comparison between two highly salient rotor structures for synchronous reluctance traction motors for electric vehicles. This work is the summary of many years of research aimed at providing an economically advantageous alternative to a currently produced induction motor drive. The traction motor must provide a wide constant power range, high overload capability, low torque ripple and limited temperature rise. For these reasons, the comparison is not limited to torque production and efficiency, but includes torque ripple, noise and temperature rise considerations. The rotors being compared all mate with a common stator structure (also used for the induction motor) but are manufactured with different technologies: it is shown that, although the axially laminated rotor allows higher saliency ratios, the radially laminated (punched) rotor provides better torque uniformity, lower temperature rise with a minor peformance degradation, at a lower manufacturing cost.
{"title":"Rotors for synchronous reluctance traction motors: a comparative study","authors":"F. Leonardi, P. Mccleer, A. ElAntably","doi":"10.1109/IAS.1999.801605","DOIUrl":"https://doi.org/10.1109/IAS.1999.801605","url":null,"abstract":"This paper presents a comparison between two highly salient rotor structures for synchronous reluctance traction motors for electric vehicles. This work is the summary of many years of research aimed at providing an economically advantageous alternative to a currently produced induction motor drive. The traction motor must provide a wide constant power range, high overload capability, low torque ripple and limited temperature rise. For these reasons, the comparison is not limited to torque production and efficiency, but includes torque ripple, noise and temperature rise considerations. The rotors being compared all mate with a common stator structure (also used for the induction motor) but are manufactured with different technologies: it is shown that, although the axially laminated rotor allows higher saliency ratios, the radially laminated (punched) rotor provides better torque uniformity, lower temperature rise with a minor peformance degradation, at a lower manufacturing cost.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"33 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":"134067261","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, a new modular motor-modular inverter (MM-MI) concept for medium voltage adjustable speed drive (MV-ASD) systems is introduced. It is shown that a standard medium voltage motor winding connections can be reconnected into several three-phase groups, each powered by a separate three-phase PWM inverter, resulting in a high performance MV-ASD system. The proposed approach is fault tolerant and can continue to operate at reduced power levels, under inverter and/or motor faults. An example 250 hp, 4 pole, 60 Hz, 2300 V/4160 V motor winding connection diagram along with the associated inverter configurations is analyzed. Results from analysis are presented on the aspects of faults and motor operation under partial winding excitation. Experimental results on a low voltage (460 V), 10 hp ASD are demonstrated.
{"title":"A new modular motor-modular inverter (MM-MI) concept for medium voltage adjustable speed drive systems","authors":"E. Cengelci, P. Enjeti, W. Gray","doi":"10.1109/IAS.1999.806008","DOIUrl":"https://doi.org/10.1109/IAS.1999.806008","url":null,"abstract":"In this paper, a new modular motor-modular inverter (MM-MI) concept for medium voltage adjustable speed drive (MV-ASD) systems is introduced. It is shown that a standard medium voltage motor winding connections can be reconnected into several three-phase groups, each powered by a separate three-phase PWM inverter, resulting in a high performance MV-ASD system. The proposed approach is fault tolerant and can continue to operate at reduced power levels, under inverter and/or motor faults. An example 250 hp, 4 pole, 60 Hz, 2300 V/4160 V motor winding connection diagram along with the associated inverter configurations is analyzed. Results from analysis are presented on the aspects of faults and motor operation under partial winding excitation. Experimental results on a low voltage (460 V), 10 hp ASD are demonstrated.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"39 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":"134223999","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 present a novel PWM control strategy that can be used for general 3 phase AC/AC series resonant DC link converters in uninterruptible power supplies (UPS) applications. The algorithm can achieve control over unity input power factor and provide low total harmonic distortions of input and output line currents. The control is performed in the DQ rotating reference frame and incorporates a modified space vector PWM strategy for determination of switching instants. A control algorithm has been derived to provide decoupling of the d and q-axis responses, allowing effective use of linear controllers to force the error signal to zero. Results from simulations and experimental studies show that a close to unity input power factor and total harmonic distortions as low as 1-2% can be achieved for both the input currents and output voltages.
{"title":"PWM control of three-phase series resonant DC link converters for UPS applications","authors":"M. Marwali, A. Keyhani","doi":"10.1109/IAS.1999.806014","DOIUrl":"https://doi.org/10.1109/IAS.1999.806014","url":null,"abstract":"This paper present a novel PWM control strategy that can be used for general 3 phase AC/AC series resonant DC link converters in uninterruptible power supplies (UPS) applications. The algorithm can achieve control over unity input power factor and provide low total harmonic distortions of input and output line currents. The control is performed in the DQ rotating reference frame and incorporates a modified space vector PWM strategy for determination of switching instants. A control algorithm has been derived to provide decoupling of the d and q-axis responses, allowing effective use of linear controllers to force the error signal to zero. Results from simulations and experimental studies show that a close to unity input power factor and total harmonic distortions as low as 1-2% can be achieved for both the input currents and output voltages.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"35 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":"133951496","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}
Our work dealt with the problems of corona wind and acoustic emission, encountered in pin-to-plane corona generators. Our generator had 19-mm electrode separation, with anode grounded and pin driven by negative voltages from three to fifteen kilovolts. The acoustic signal generated by the corona discharge was received with a microphone (B=10 kHz, at 3 dB). Both the corona generator and microphone were placed in an acoustic anechoic chamber and samples of the acoustic signal for different voltages and corona currents taken. The sampling and on-line analysis of the signal was performed by a signal processing system (Motorola, DSP 56300, r/sub s/=43/spl times/10/sup 3/ s/sup -1/), and a PC. The time domain signal was filtered and acquired in the time domain, then Fourier transformed into the frequency domain, to yield the acoustic signature of the wind, produced by the negative corona. The corona acoustic emission expressed in terms of energy is directly proportional to the intensity of the field, which sustains the corona discharge. The acoustic signal spectrum at low voltages shows a fundamental and a number of harmonic components, superimposed on the spectrum of white noise, with a signal-to-noise ratio of better than one to five. At higher voltages, harmonic components are no longer present, and the acoustic signal energy is emitted in a single spectral line. Although the measurements were performed mostly with a pin-to-plane generator, the results and the developed technique were applied to a cylindrical and to an array generator, with similar results.
{"title":"Corona wind in a system with the pin-to-plane discharge geometry","authors":"Z. Kucerovsky, G.D. Greason, A. Weigl","doi":"10.1109/IAS.1999.799918","DOIUrl":"https://doi.org/10.1109/IAS.1999.799918","url":null,"abstract":"Our work dealt with the problems of corona wind and acoustic emission, encountered in pin-to-plane corona generators. Our generator had 19-mm electrode separation, with anode grounded and pin driven by negative voltages from three to fifteen kilovolts. The acoustic signal generated by the corona discharge was received with a microphone (B=10 kHz, at 3 dB). Both the corona generator and microphone were placed in an acoustic anechoic chamber and samples of the acoustic signal for different voltages and corona currents taken. The sampling and on-line analysis of the signal was performed by a signal processing system (Motorola, DSP 56300, r/sub s/=43/spl times/10/sup 3/ s/sup -1/), and a PC. The time domain signal was filtered and acquired in the time domain, then Fourier transformed into the frequency domain, to yield the acoustic signature of the wind, produced by the negative corona. The corona acoustic emission expressed in terms of energy is directly proportional to the intensity of the field, which sustains the corona discharge. The acoustic signal spectrum at low voltages shows a fundamental and a number of harmonic components, superimposed on the spectrum of white noise, with a signal-to-noise ratio of better than one to five. At higher voltages, harmonic components are no longer present, and the acoustic signal energy is emitted in a single spectral line. Although the measurements were performed mostly with a pin-to-plane generator, the results and the developed technique were applied to a cylindrical and to an array generator, with similar results.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"71 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":"134298081","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 performances of three different types of plasma reactors such as ferroelectric packed-bed (FPB), pulsed corona (PCR), and silent discharge (SDP) were compared in the decomposition of trichloroethylene (Cl/sub 2/C=CHCl, TCE), bromomethane (CH/sub 3/Br), and tetrafluoromethane (CF/sub 4/). Irrespective of reactors, HAP (hazardous air pollutants) reactivity decreased in the order: TCE>CH/sub 3/Br>CF/sub 4/. Similar byproducts were obtained with any of the above reactors, and similar trends were observed in the HAP decomposition rate-retarding effect by gaseous oxygen and water. In the TCE decomposition, PCR was extremely effective and 1000 ppm of TCE almost completely decomposed in dry nitrogen at 0.09 s of residence time, but its performance went down in the CH/sub 3/Br decomposition. Comparable performances were observed for FPB and SDP, and CF/sub 4/ conversions were little higher with SDP than with FPB at the same specific energy densities.
{"title":"Comparison of reactor performance in the nonthermal plasma chemical processing of hazardous air pollutants","authors":"S. Futamura, H. Einaga, A. Zhang","doi":"10.1109/IAS.1999.801642","DOIUrl":"https://doi.org/10.1109/IAS.1999.801642","url":null,"abstract":"The performances of three different types of plasma reactors such as ferroelectric packed-bed (FPB), pulsed corona (PCR), and silent discharge (SDP) were compared in the decomposition of trichloroethylene (Cl/sub 2/C=CHCl, TCE), bromomethane (CH/sub 3/Br), and tetrafluoromethane (CF/sub 4/). Irrespective of reactors, HAP (hazardous air pollutants) reactivity decreased in the order: TCE>CH/sub 3/Br>CF/sub 4/. Similar byproducts were obtained with any of the above reactors, and similar trends were observed in the HAP decomposition rate-retarding effect by gaseous oxygen and water. In the TCE decomposition, PCR was extremely effective and 1000 ppm of TCE almost completely decomposed in dry nitrogen at 0.09 s of residence time, but its performance went down in the CH/sub 3/Br decomposition. Comparable performances were observed for FPB and SDP, and CF/sub 4/ conversions were little higher with SDP than with FPB at the same specific energy densities.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"165 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":"131576636","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 presents the design and experiment of a hybrid fuzzy control scheme for a high performance brushless DC motor drive system. Both the design of the fuzzy controller and its integration with the proportional integral (PI) in a global control scheme are discussed. The principle of the proposed control scheme is to use a PI controller, which performs satisfactorily in most cases, while keeping in the background, a fuzzy controller, which, is ready to take over the PI controller when severe perturbations occur. Performance of the hybrid fuzzy-PI controller is evaluated through a laboratory implementation. The laboratory implementation is based on a linguistic fuzzy controller whose design is derived from the expert knowledge during disturbed phases. Experimental results have shown excellent tracking performance of the hybrid control system, and have convincingly demonstrated the usefulness of the hybrid fuzzy controller in high performance drives with uncertainties.
{"title":"Experimental verification of a hybrid fuzzy controller for a high performance brushless DC drive system","authors":"A. Rubaai, D. Ricketts, M. D. Kankam","doi":"10.1109/IAS.1999.801633","DOIUrl":"https://doi.org/10.1109/IAS.1999.801633","url":null,"abstract":"This paper presents the design and experiment of a hybrid fuzzy control scheme for a high performance brushless DC motor drive system. Both the design of the fuzzy controller and its integration with the proportional integral (PI) in a global control scheme are discussed. The principle of the proposed control scheme is to use a PI controller, which performs satisfactorily in most cases, while keeping in the background, a fuzzy controller, which, is ready to take over the PI controller when severe perturbations occur. Performance of the hybrid fuzzy-PI controller is evaluated through a laboratory implementation. The laboratory implementation is based on a linguistic fuzzy controller whose design is derived from the expert knowledge during disturbed phases. Experimental results have shown excellent tracking performance of the hybrid control system, and have convincingly demonstrated the usefulness of the hybrid fuzzy controller in high performance drives with uncertainties.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"39 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":"132822750","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}
Capacitors are utilised in a variety of different ways in power electronic circuits. Typical applications are in snubber, clamping and resonant circuits. For design purposes, it is necessary to make an accurate measurement of the actual behaviour of the capacitance that is added to the circuit under conditions related to those prevailing in a converter. For this purpose, a number of different measurement systems or techniques can be utilised. Four of these measurement systems are compared. These are small signal, variable frequency measurement, large signal quasi-DC measurement, in-situ high voltage measurement and small signal with large bias voltage measurement. Each of these measurement techniques returns characteristic values based on its particular model of the test capacitor. These tests are done on both ceramic and nonceramic capacitors at room temperature. The results are discussed.
{"title":"Capacitor measurements for power electronic applications","authors":"J. Strydom, J. V. van Wyk, J. Ferreira","doi":"10.1109/IAS.1999.799182","DOIUrl":"https://doi.org/10.1109/IAS.1999.799182","url":null,"abstract":"Capacitors are utilised in a variety of different ways in power electronic circuits. Typical applications are in snubber, clamping and resonant circuits. For design purposes, it is necessary to make an accurate measurement of the actual behaviour of the capacitance that is added to the circuit under conditions related to those prevailing in a converter. For this purpose, a number of different measurement systems or techniques can be utilised. Four of these measurement systems are compared. These are small signal, variable frequency measurement, large signal quasi-DC measurement, in-situ high voltage measurement and small signal with large bias voltage measurement. Each of these measurement techniques returns characteristic values based on its particular model of the test capacitor. These tests are done on both ceramic and nonceramic capacitors at room temperature. The results are discussed.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"62 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":"133353592","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 presents a novel usage of a dual stator winding, three-phase induction machine as a stand-alone generator with both controlled output load voltage magnitude and frequency. This generator, with both three-phase power and control windings housed in the stator structure, has the load connected to the power winding and a three-phase PWM voltage source inverter sourcing the control winding. The input to the PWM inverter is either a battery source or a charged DC capacitor. The operational characteristics of these generator schemes with either of the two inverter sources is investigated and shown to have desirable performance. How the load voltage magnitude depends on the various control and design parameters such as rotor speed, compensating capacitance and load impedance are determined using a detailed mathematical model of the system which is confirmed to accurately predict dynamic and steady-state performance characteristics.
{"title":"PWM-VSI inverter assisted stand-alone dual stator winding induction generator","authors":"O. Ojo, I. Davidson","doi":"10.1109/IAS.1999.805950","DOIUrl":"https://doi.org/10.1109/IAS.1999.805950","url":null,"abstract":"This paper presents a novel usage of a dual stator winding, three-phase induction machine as a stand-alone generator with both controlled output load voltage magnitude and frequency. This generator, with both three-phase power and control windings housed in the stator structure, has the load connected to the power winding and a three-phase PWM voltage source inverter sourcing the control winding. The input to the PWM inverter is either a battery source or a charged DC capacitor. The operational characteristics of these generator schemes with either of the two inverter sources is investigated and shown to have desirable performance. How the load voltage magnitude depends on the various control and design parameters such as rotor speed, compensating capacitance and load impedance are determined using a detailed mathematical model of the system which is confirmed to accurately predict dynamic and steady-state performance characteristics.","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":"133645632","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 is on a novel use of lighting or signaling devices constructed by light-emitting diodes(LEDs). The idea is on their concurrent use for simultaneous signaling and communications. The visible light from LEDs can be modulated and encoded with audio or data signal. Hence, an LED indicator lamp or traffic light can become an information broadcasting device. Such a system made up of high brightness visible LEDs can provide the function of open space, wireless broadcasting of audio or data signals. An implemented system with experimental results is shown. A portable receiver is designed to demodulate the optically transmitted information. The distance for audio transmission of an LED traffic light can reach over 20 m. The optical link employs intensity modulation with direct detection. The system is limited to line-of-sight communications. However, this concurrent use of LEDs will open up many new applications.
{"title":"Optical wireless based on high brightness visible LEDs","authors":"Grantham K. H. Pang, T. Kwan, H. Liu, Chi-Ho Chan","doi":"10.1109/IAS.1999.805968","DOIUrl":"https://doi.org/10.1109/IAS.1999.805968","url":null,"abstract":"This paper is on a novel use of lighting or signaling devices constructed by light-emitting diodes(LEDs). The idea is on their concurrent use for simultaneous signaling and communications. The visible light from LEDs can be modulated and encoded with audio or data signal. Hence, an LED indicator lamp or traffic light can become an information broadcasting device. Such a system made up of high brightness visible LEDs can provide the function of open space, wireless broadcasting of audio or data signals. An implemented system with experimental results is shown. A portable receiver is designed to demodulate the optically transmitted information. The distance for audio transmission of an LED traffic light can reach over 20 m. The optical link employs intensity modulation with direct detection. The system is limited to line-of-sight communications. However, this concurrent use of LEDs will open up many new applications.","PeriodicalId":125787,"journal":{"name":"Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)","volume":"43 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":"127815656","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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