Pub Date : 1993-10-17DOI: 10.1109/CEIDP.1993.378919
C. Araki, T. Taguchi
The thermal degradation mechanism of EI (polyester imide) film on copper and aluminum wire was investigated. The effects of the metallic conductor on the degradation behavior and diagnosis methods applied to the EI films are reviewed. The physico-chemical properties were evaluated using a thermogravimetric analyzer, a Fourier-transform infrared (FTIR) spectrophotometer with a pyrolytic gaschromatograph (PGC) with FTIR. The degradation of EI was found to be accelerated by the presence of copper. In the presence of copper, decomposition of imide and ester bonds occurred simultaneously, resulting in a decrease in the breakdown stress. The PGC method was found to be effective for the insulation diagnosis of EI and the analysis of degradation mechanisms.<>
{"title":"Thermal degradation of polyesterimide magnet wire","authors":"C. Araki, T. Taguchi","doi":"10.1109/CEIDP.1993.378919","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378919","url":null,"abstract":"The thermal degradation mechanism of EI (polyester imide) film on copper and aluminum wire was investigated. The effects of the metallic conductor on the degradation behavior and diagnosis methods applied to the EI films are reviewed. The physico-chemical properties were evaluated using a thermogravimetric analyzer, a Fourier-transform infrared (FTIR) spectrophotometer with a pyrolytic gaschromatograph (PGC) with FTIR. The degradation of EI was found to be accelerated by the presence of copper. In the presence of copper, decomposition of imide and ester bonds occurred simultaneously, resulting in a decrease in the breakdown stress. The PGC method was found to be effective for the insulation diagnosis of EI and the analysis of degradation mechanisms.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115239776","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378889
W.M. Al-Hasai, A. Hossam-eldin, A. Pearmain
The phenomena of water treeing (WT) were simulated using finite-difference programs. The main parameters were investigated, and a comparison was made between the simulated results and experimental work. The point-plane model used to initiate and grow WTs is simulated. The programs calculated the equipotential distribution and the fields. Changing the permitivities of some parts in the grid used represented the propagation of voids in the model. Good agreement was obtained between simulation results and experimental work, some more simulation work has to be done.<>
{"title":"Computer simulation for water treeing in polymeric materials","authors":"W.M. Al-Hasai, A. Hossam-eldin, A. Pearmain","doi":"10.1109/CEIDP.1993.378889","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378889","url":null,"abstract":"The phenomena of water treeing (WT) were simulated using finite-difference programs. The main parameters were investigated, and a comparison was made between the simulated results and experimental work. The point-plane model used to initiate and grow WTs is simulated. The programs calculated the equipotential distribution and the fields. Changing the permitivities of some parts in the grid used represented the propagation of voids in the model. Good agreement was obtained between simulation results and experimental work, some more simulation work has to be done.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127057394","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378949
J.F. Liu, G. Raju
Corona discharge in SF/sub 6/ is analyzed avoiding the equilibrium assumption. This is accomplished by a Monte Carlo simulation of electrons, considering the ionization, attachment, and photoionization processes, and finding the solution to Poisson's equation for the space charge field. The current pulses simulated at various voltages are found to have more than one peak. This agrees with experimental observation. The current lasts several nanoseconds depending on the voltage. The development of electron avalanches due to ionization and photoionization are displayed in great detail. The quenching of the electrons at later surges is due to space-charge field suppression.<>
{"title":"Negative corona discharges in SF/sub 6/","authors":"J.F. Liu, G. Raju","doi":"10.1109/CEIDP.1993.378949","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378949","url":null,"abstract":"Corona discharge in SF/sub 6/ is analyzed avoiding the equilibrium assumption. This is accomplished by a Monte Carlo simulation of electrons, considering the ionization, attachment, and photoionization processes, and finding the solution to Poisson's equation for the space charge field. The current pulses simulated at various voltages are found to have more than one peak. This agrees with experimental observation. The current lasts several nanoseconds depending on the voltage. The development of electron avalanches due to ionization and photoionization are displayed in great detail. The quenching of the electrons at later surges is due to space-charge field suppression.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126851932","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378880
É. David, J. Parpal, J. Crine
The authors investigate the influence of both passive internal strains in drawn PE (polyethylene) samples with semiconductive electrodes and active internal stresses around embedded steel electrodes on the electrical tree growth. Results of insitu photoelastic measurements showing the fringe pattern evolution accompanying tree propagation are also presented. It has been found that the internal stress model developed by J. V. Champion et al (1992) for embedded electrodes in an epoxy resin block can be successfully applied to polyethylene samples. Photoelastic measurement is an efficient and simple tool for experimental determination of such stresses. The electrical performance of polyethylene samples show complex variations in the presence of increasing internal strain. Orientation effects (passive internal stresses) and residual stresses (active internal stresses) might make different contributions, possibly in opposite directions. Nevertheless, it is believed that polyethylene specimens oriented perpendicularly to the make electric field have better resistance to electrical treeing than unoriented samples.<>
{"title":"In-situ photoelastic monitoring of electrical treeing in polyethylene","authors":"É. David, J. Parpal, J. Crine","doi":"10.1109/CEIDP.1993.378880","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378880","url":null,"abstract":"The authors investigate the influence of both passive internal strains in drawn PE (polyethylene) samples with semiconductive electrodes and active internal stresses around embedded steel electrodes on the electrical tree growth. Results of insitu photoelastic measurements showing the fringe pattern evolution accompanying tree propagation are also presented. It has been found that the internal stress model developed by J. V. Champion et al (1992) for embedded electrodes in an epoxy resin block can be successfully applied to polyethylene samples. Photoelastic measurement is an efficient and simple tool for experimental determination of such stresses. The electrical performance of polyethylene samples show complex variations in the presence of increasing internal strain. Orientation effects (passive internal stresses) and residual stresses (active internal stresses) might make different contributions, possibly in opposite directions. Nevertheless, it is believed that polyethylene specimens oriented perpendicularly to the make electric field have better resistance to electrical treeing than unoriented samples.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114444379","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378894
Y. Miyashita, Y. Makishi, H. Kato
The authors have studied the basic electrical behavior of semiconducting materials employing a variety of CB (carbon black) loading amounts dispersed in several polyolefins. In the present work, the electrical conductivity of CB filled semiconducting materials is shown to depend on the nature of the CB network in the polymer matrix. The growth of the network may be accelerated by thermal vibration since higher molding temperature gives stable and enhanced conductivity. Both the amount of bound polymer and the dielectric breakdown strength seemed to predict the level of CB network development. Transmission electron microscope (TEM) observation of these semicon materials gave direct evidence for a well-grown CB network with high electrical conductivity.<>
{"title":"New approach to elucidate the properties of carbon black-filled semiconducting materials for high voltage power cables","authors":"Y. Miyashita, Y. Makishi, H. Kato","doi":"10.1109/CEIDP.1993.378894","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378894","url":null,"abstract":"The authors have studied the basic electrical behavior of semiconducting materials employing a variety of CB (carbon black) loading amounts dispersed in several polyolefins. In the present work, the electrical conductivity of CB filled semiconducting materials is shown to depend on the nature of the CB network in the polymer matrix. The growth of the network may be accelerated by thermal vibration since higher molding temperature gives stable and enhanced conductivity. Both the amount of bound polymer and the dielectric breakdown strength seemed to predict the level of CB network development. Transmission electron microscope (TEM) observation of these semicon materials gave direct evidence for a well-grown CB network with high electrical conductivity.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"90 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121678611","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378957
R. Sundararaman, C. Li, S. Goode, T. Sudarshan
Spectroscopic investigations of the prebreakdown and breakdown luminescence of a dielectric surface under the application of a high-voltage pulse were performed in vacuum ambience on polycrystalline alumina. Information about the composition of the light emission was obtained with the aid of a 2D CCD (charge coupled device) camera interfaced with a flat field spectrometer. Time-resolved studies of the light emission were also done using two PMTs (photomultiplier) tubes with spectral response in the UV and visible region. The surface of the insulator was treated with different polishing media like silicon carbine discs and diamond paste in order to understand the role played by the surface microstructure of the sample. The results reported indicate that the surface treatment of a dielectric plays a very important role in the electrical performance of the insulator. In addition, it is evident that there are significant differences in the spectral nature of the light emission that can be observed from the spectrum of surface flashover from a SiC polished sample compared to that of an unpolished sample. A correlation between the electrical performance of the insulator and the development of the spectral nature of the light emission is indicated. All these interesting and important observations are being investigated in an extensive manner. The important role played by material defects and desorbed gases in the pre-breakdown phase of the surface flashover events are again confirmed.<>
{"title":"Spectroscopic observations of light emission from surface flashover of insulators under high voltage stress","authors":"R. Sundararaman, C. Li, S. Goode, T. Sudarshan","doi":"10.1109/CEIDP.1993.378957","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378957","url":null,"abstract":"Spectroscopic investigations of the prebreakdown and breakdown luminescence of a dielectric surface under the application of a high-voltage pulse were performed in vacuum ambience on polycrystalline alumina. Information about the composition of the light emission was obtained with the aid of a 2D CCD (charge coupled device) camera interfaced with a flat field spectrometer. Time-resolved studies of the light emission were also done using two PMTs (photomultiplier) tubes with spectral response in the UV and visible region. The surface of the insulator was treated with different polishing media like silicon carbine discs and diamond paste in order to understand the role played by the surface microstructure of the sample. The results reported indicate that the surface treatment of a dielectric plays a very important role in the electrical performance of the insulator. In addition, it is evident that there are significant differences in the spectral nature of the light emission that can be observed from the spectrum of surface flashover from a SiC polished sample compared to that of an unpolished sample. A correlation between the electrical performance of the insulator and the development of the spectral nature of the light emission is indicated. All these interesting and important observations are being investigated in an extensive manner. The important role played by material defects and desorbed gases in the pre-breakdown phase of the surface flashover events are again confirmed.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115032240","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378876
J. Koo, H. Kim, K. Kim, Y. Ann
Systematic investigations have been carried out to compare the aging characteristics of 22.9kV XLPE (cross-linked polyethylene) power cables which might be dependent not only on the different types of curing processes on the various antioxidant additives. Sample cables were aged at 60 Hz and 41kV (3Uo), for which hot water at 70/spl deg/C was introduced between the conductor and the semiconductive layer during up to 8760 hrs in a water bath. Afterwards, the AC breakdown characteristics of these aged cables were measured. In a microscopic analysis of the insulating materials, water trees, crystallinity, and oxidation level were measured using a sliced specimen cut into radial sections.<>
{"title":"An experimental investigation on the degradation characteristics of 22.9kV XLPE cables; dependence on the compounds and curing process","authors":"J. Koo, H. Kim, K. Kim, Y. Ann","doi":"10.1109/CEIDP.1993.378876","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378876","url":null,"abstract":"Systematic investigations have been carried out to compare the aging characteristics of 22.9kV XLPE (cross-linked polyethylene) power cables which might be dependent not only on the different types of curing processes on the various antioxidant additives. Sample cables were aged at 60 Hz and 41kV (3Uo), for which hot water at 70/spl deg/C was introduced between the conductor and the semiconductive layer during up to 8760 hrs in a water bath. Afterwards, the AC breakdown characteristics of these aged cables were measured. In a microscopic analysis of the insulating materials, water trees, crystallinity, and oxidation level were measured using a sliced specimen cut into radial sections.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114934661","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378910
B. N. Rao, K. Mallikarjunappa, C. Keri, S. N. Moorching
Field testing and extensive laboratory investigations indicate that periodic diagnostic tests such as tan delta, capacitance, and IDE (integrated discharge energy) give useful information on the relative condition of winding insulation. Each test parameter provides particular information regarding the condition of stator insulation should be monitored and as many diagnostic parameters as possible should be monitored to obtain reliable and complete information regarding the state, quality, and trend in ageing of the insulation. A strong correlation has been shown to exist between tan delta and capacitance tip-ups.<>
{"title":"Experience with dielectric diagnosis of high voltage motors in service","authors":"B. N. Rao, K. Mallikarjunappa, C. Keri, S. N. Moorching","doi":"10.1109/CEIDP.1993.378910","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378910","url":null,"abstract":"Field testing and extensive laboratory investigations indicate that periodic diagnostic tests such as tan delta, capacitance, and IDE (integrated discharge energy) give useful information on the relative condition of winding insulation. Each test parameter provides particular information regarding the condition of stator insulation should be monitored and as many diagnostic parameters as possible should be monitored to obtain reliable and complete information regarding the state, quality, and trend in ageing of the insulation. A strong correlation has been shown to exist between tan delta and capacitance tip-ups.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"288 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121072987","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378900
D. Ryder
The author discusses partial discharge (PD) measurements with insulation damage and ageing, and presents evidence of various stages of solid dielectric deterioration. It is shown that the effect of these processes on measurements is demonstrated. The effects of PD activity within internal voids or cavities caused by delamination can produce acidic by-products, which then affect the surface conductivity. An attempt is made to identify processes that can cause confusion in the interpretation of results and propose an engineering option.<>
{"title":"The interpretation of partial electrical discharge measurements with insulation damage and ageing","authors":"D. Ryder","doi":"10.1109/CEIDP.1993.378900","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378900","url":null,"abstract":"The author discusses partial discharge (PD) measurements with insulation damage and ageing, and presents evidence of various stages of solid dielectric deterioration. It is shown that the effect of these processes on measurements is demonstrated. The effects of PD activity within internal voids or cavities caused by delamination can produce acidic by-products, which then affect the surface conductivity. An attempt is made to identify processes that can cause confusion in the interpretation of results and propose an engineering option.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116380841","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378875
S. Nakamura, A. Ito, G. Sawa, K. Kitagawa, T. Hanada, A. Ueno
The temperature dependence of the resistivity and dielectric properties of carbon black-polyethylene composites was measured in the temperature range from room temperature to 95 /spl deg/C. The composites show a dielectric relaxation, which obeys a Cole-Cole circular arc law. The strength of relaxation, /spl delta/ /spl epsi/, and the parameter /spl beta/, a measure of the distribution of relaxation time, were estimated from the Cole-Cole plot. It is suggested that the rapid increase of resistivity observed about 70 /spl deg/C is due to a scission of conducting paths caused by the thermal expansion of the resin, because of the increase of /spl delta/ /spl epsi/ above 70 /spl deg/C. The decrement of /spl beta/ indicates that the scission makes the distribution of relaxation broader. In the temperature region below 70 /spl deg/C, /spl delta/, /spl epsi/ decreases with heating. It is concluded that branches likely combine to conducting paths, bringing about a mild increase in resistivity with increasing temperature.<>
{"title":"Temperature dependence of resistivity and dielectric property of furnace carbon black-polyethylene composite","authors":"S. Nakamura, A. Ito, G. Sawa, K. Kitagawa, T. Hanada, A. Ueno","doi":"10.1109/CEIDP.1993.378875","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378875","url":null,"abstract":"The temperature dependence of the resistivity and dielectric properties of carbon black-polyethylene composites was measured in the temperature range from room temperature to 95 /spl deg/C. The composites show a dielectric relaxation, which obeys a Cole-Cole circular arc law. The strength of relaxation, /spl delta/ /spl epsi/, and the parameter /spl beta/, a measure of the distribution of relaxation time, were estimated from the Cole-Cole plot. It is suggested that the rapid increase of resistivity observed about 70 /spl deg/C is due to a scission of conducting paths caused by the thermal expansion of the resin, because of the increase of /spl delta/ /spl epsi/ above 70 /spl deg/C. The decrement of /spl beta/ indicates that the scission makes the distribution of relaxation broader. In the temperature region below 70 /spl deg/C, /spl delta/, /spl epsi/ decreases with heating. It is concluded that branches likely combine to conducting paths, bringing about a mild increase in resistivity with increasing temperature.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116403091","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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