Pub Date : 2002-04-07DOI: 10.1109/ELINSL.2002.995981
R. Bruetsch, R. Schwander, F. Wolf, Marco Naegelin
The driving force of material and process development in the insulation technology of rotating high voltage machines has changed in the last ten to fifteen years. Being mainly technology driven in the past, cost has become the determining factor in the industry. Improvements in products or processing are only accepted if they reduce overall cost. On the other hand, high voltage motors and generators are long-life capital goods and a reduction in reliability cannot be tolerated. To be successful in the market any development of new insulating materials has to reflect these facts. For this reason a new range of fast curing products for the consolidation of Roebel bars and double layer coils has been developed. The application of the new fast curing materials can be automated using new types of equipment for the production and consolidation of Roebel bars. The new fast curing materials provide a substantial reduction of. processing time and saving of hot press capacity and energy. Together with the new automated Roebelling and application equipment they go a long way towards cost reduction in the production of rotating high voltage machines.
{"title":"New insulating materials and process equipment for the consolidation of coils and Roebel bars","authors":"R. Bruetsch, R. Schwander, F. Wolf, Marco Naegelin","doi":"10.1109/ELINSL.2002.995981","DOIUrl":"https://doi.org/10.1109/ELINSL.2002.995981","url":null,"abstract":"The driving force of material and process development in the insulation technology of rotating high voltage machines has changed in the last ten to fifteen years. Being mainly technology driven in the past, cost has become the determining factor in the industry. Improvements in products or processing are only accepted if they reduce overall cost. On the other hand, high voltage motors and generators are long-life capital goods and a reduction in reliability cannot be tolerated. To be successful in the market any development of new insulating materials has to reflect these facts. For this reason a new range of fast curing products for the consolidation of Roebel bars and double layer coils has been developed. The application of the new fast curing materials can be automated using new types of equipment for the production and consolidation of Roebel bars. The new fast curing materials provide a substantial reduction of. processing time and saving of hot press capacity and energy. Together with the new automated Roebelling and application equipment they go a long way towards cost reduction in the production of rotating high voltage machines.","PeriodicalId":10532,"journal":{"name":"Conference Record of the the 2002 IEEE International Symposium on Electrical Insulation (Cat. No.02CH37316)","volume":"7 1","pages":"488-491"},"PeriodicalIF":0.0,"publicationDate":"2002-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81082895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-04-07DOI: 10.1109/ELINSL.2002.996003
D. Gross
With respect to the basic gas discharge physics, the rise time of an electron avalanche under nitrogen atmosphere results in a partial discharge signal bandwidth of several hundreds of MHz. However, in terms of high frequency properties, a rotating machine acts as a highly complex network. Mismatch of impedance and other effects hamper the applicability of different frequency bands for partial discharge testing. The epoxy-mica insulation system widely tolerates partial discharge. Thus, partial discharge activity often serves as an indicator for other defect mechanism, such as mechanical, thermal, or environmental influence.
{"title":"Partial discharge measurement and monitoring on rotating machines","authors":"D. Gross","doi":"10.1109/ELINSL.2002.996003","DOIUrl":"https://doi.org/10.1109/ELINSL.2002.996003","url":null,"abstract":"With respect to the basic gas discharge physics, the rise time of an electron avalanche under nitrogen atmosphere results in a partial discharge signal bandwidth of several hundreds of MHz. However, in terms of high frequency properties, a rotating machine acts as a highly complex network. Mismatch of impedance and other effects hamper the applicability of different frequency bands for partial discharge testing. The epoxy-mica insulation system widely tolerates partial discharge. Thus, partial discharge activity often serves as an indicator for other defect mechanism, such as mechanical, thermal, or environmental influence.","PeriodicalId":10532,"journal":{"name":"Conference Record of the the 2002 IEEE International Symposium on Electrical Insulation (Cat. No.02CH37316)","volume":"10 1","pages":"570-574"},"PeriodicalIF":0.0,"publicationDate":"2002-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83662401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-04-07DOI: 10.1109/ELINSL.2002.995957
R. Kotte, E. Gockenbach, H. Borsi
Experimental investigations concerning the influence of the cure parameters on the partial discharge inception voltage (PDIV) of four heat-resistant cast resin systems are presented and discussed in this paper. The tests were performed on two epoxy resin systems in combination with silica flour and wollastonite, respectively, with different post-cure parameters. The PDIV was measured in a nonuniform electrical field in dependence on the temperature. The contribution reveals that a raise of the cure temperature can lead to a significant decline of the PDIV.
{"title":"Influence of the cure parameters on the partial discharge behavior of cast resins","authors":"R. Kotte, E. Gockenbach, H. Borsi","doi":"10.1109/ELINSL.2002.995957","DOIUrl":"https://doi.org/10.1109/ELINSL.2002.995957","url":null,"abstract":"Experimental investigations concerning the influence of the cure parameters on the partial discharge inception voltage (PDIV) of four heat-resistant cast resin systems are presented and discussed in this paper. The tests were performed on two epoxy resin systems in combination with silica flour and wollastonite, respectively, with different post-cure parameters. The PDIV was measured in a nonuniform electrical field in dependence on the temperature. The contribution reveals that a raise of the cure temperature can lead to a significant decline of the PDIV.","PeriodicalId":10532,"journal":{"name":"Conference Record of the the 2002 IEEE International Symposium on Electrical Insulation (Cat. No.02CH37316)","volume":"1 1","pages":"387-390"},"PeriodicalIF":0.0,"publicationDate":"2002-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89495859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-04-07DOI: 10.1109/ELINSL.2002.995870
Xiongwei Jiang, Gang Liu, Guangchun Zhang, Guangning Wu
Generally there are four types of defects inside the stator bar insulation of large generators, i.e. void, internal delamination, crack and delamination at conduct edge. It's evident that these four types of internal defects appear at the different stages of aging and play significantly different roles in the aging and ultimate failure of stator bar insulation. Thus it makes sense to distinguish them. In this paper, partial discharge experiments were performed on four elaborate model defects to establish a firm basis for the recognition of defect type.
{"title":"Study on PD characteristics of insulation internal defects of large generator stator bar","authors":"Xiongwei Jiang, Gang Liu, Guangchun Zhang, Guangning Wu","doi":"10.1109/ELINSL.2002.995870","DOIUrl":"https://doi.org/10.1109/ELINSL.2002.995870","url":null,"abstract":"Generally there are four types of defects inside the stator bar insulation of large generators, i.e. void, internal delamination, crack and delamination at conduct edge. It's evident that these four types of internal defects appear at the different stages of aging and play significantly different roles in the aging and ultimate failure of stator bar insulation. Thus it makes sense to distinguish them. In this paper, partial discharge experiments were performed on four elaborate model defects to establish a firm basis for the recognition of defect type.","PeriodicalId":10532,"journal":{"name":"Conference Record of the the 2002 IEEE International Symposium on Electrical Insulation (Cat. No.02CH37316)","volume":"35 1","pages":"14-18"},"PeriodicalIF":0.0,"publicationDate":"2002-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79243246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-04-07DOI: 10.1109/ELINSL.2002.995973
W. Song, D.I. Yang, Y.H. Chung, D.S. Kim, H. S. Koh
This study aims to analyze the performance of the SF/sub 6//N/sub 2/ mixtures that can be a substitute for SF/sub 6/ in gas circuit breaker (GCB). The interrupting capability of SF/sub 6//N/sub 2/ mixtures were verified in real GCB with N/sub 2/ percentage varying from 0 to 50%. We carried out the current interrupting tests of SF/sub 6//N/sub 2/ mixtures by using a 170 kV puffer-type GCB at a laboratory. The results obtained from this study show that a 25% of N/sub 2/ mixture has an equivalent current-interrupting capability to pure SF/sub 6/ and a 50% of N/sub 2/ mixture has lesser capabilities. We will test a 75% of N/sub 2/ mixture soon and by using the test results, we develop a new-type interrupter of gas mixture.
{"title":"A study of large current interrupting capability of SF/sub 6//N/sub 2/ mixtures","authors":"W. Song, D.I. Yang, Y.H. Chung, D.S. Kim, H. S. Koh","doi":"10.1109/ELINSL.2002.995973","DOIUrl":"https://doi.org/10.1109/ELINSL.2002.995973","url":null,"abstract":"This study aims to analyze the performance of the SF/sub 6//N/sub 2/ mixtures that can be a substitute for SF/sub 6/ in gas circuit breaker (GCB). The interrupting capability of SF/sub 6//N/sub 2/ mixtures were verified in real GCB with N/sub 2/ percentage varying from 0 to 50%. We carried out the current interrupting tests of SF/sub 6//N/sub 2/ mixtures by using a 170 kV puffer-type GCB at a laboratory. The results obtained from this study show that a 25% of N/sub 2/ mixture has an equivalent current-interrupting capability to pure SF/sub 6/ and a 50% of N/sub 2/ mixture has lesser capabilities. We will test a 75% of N/sub 2/ mixture soon and by using the test results, we develop a new-type interrupter of gas mixture.","PeriodicalId":10532,"journal":{"name":"Conference Record of the the 2002 IEEE International Symposium on Electrical Insulation (Cat. No.02CH37316)","volume":"11 1","pages":"457-459"},"PeriodicalIF":0.0,"publicationDate":"2002-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78074673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-04-07DOI: 10.1109/ELINSL.2002.996001
H. Zhu, V. Green, D. Huynh
Rotating machine failures due to insulation breakdown can cause catastrophic damages to the equipment, loss or de-rating of power output, lengthy forced outages and heavy costs to the utility. Therefore it is desirable to detect the onset of significant insulation deterioration and identify potential failures as early as possible. As in the medical field, regular testing and early detection of problems mean better chances of survival for the 'patient'. Faced with increasing pressure to increase unit availability yet reduce maintenance costs, utilities are moving away from time-based maintenance practices to condition-based maintenance efforts. Owners of generators and large motors are using on-line partial discharge analysis (PDA) systems for condition monitoring of the stator insulation system. Regular condition monitoring of the stator winding insulation can give users the confidence to safely operate machines, even ones that have suffered some degree of insulation degradation. This paper presents two case studies of how utilities applied an online PD testing system on a generator and a motor with insulation degradation to avoid substantial costs and forced outages. Long-term online PD monitoring has given the utilities confidence to continue running machines that have the potential for insulation failures.
{"title":"Lifetime extension experience on rotating machine insulation using on-line PD testing","authors":"H. Zhu, V. Green, D. Huynh","doi":"10.1109/ELINSL.2002.996001","DOIUrl":"https://doi.org/10.1109/ELINSL.2002.996001","url":null,"abstract":"Rotating machine failures due to insulation breakdown can cause catastrophic damages to the equipment, loss or de-rating of power output, lengthy forced outages and heavy costs to the utility. Therefore it is desirable to detect the onset of significant insulation deterioration and identify potential failures as early as possible. As in the medical field, regular testing and early detection of problems mean better chances of survival for the 'patient'. Faced with increasing pressure to increase unit availability yet reduce maintenance costs, utilities are moving away from time-based maintenance practices to condition-based maintenance efforts. Owners of generators and large motors are using on-line partial discharge analysis (PDA) systems for condition monitoring of the stator insulation system. Regular condition monitoring of the stator winding insulation can give users the confidence to safely operate machines, even ones that have suffered some degree of insulation degradation. This paper presents two case studies of how utilities applied an online PD testing system on a generator and a motor with insulation degradation to avoid substantial costs and forced outages. Long-term online PD monitoring has given the utilities confidence to continue running machines that have the potential for insulation failures.","PeriodicalId":10532,"journal":{"name":"Conference Record of the the 2002 IEEE International Symposium on Electrical Insulation (Cat. No.02CH37316)","volume":"7 1","pages":"561-564"},"PeriodicalIF":0.0,"publicationDate":"2002-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74024496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-04-07DOI: 10.1109/ELINSL.2002.995963
C. Bak, B. Bak‐Jensen, J. T. Sørensen
Most hardware for use in HV systems requires a thorough geometric design concerning the inception of breakdown (partial discharges, corona). Work shows an interest in such corona onset design optimization criteria. Corona onset optimization is based on numerical E-field calculations and different methods for determination of onset/no onset. Practical HV equipment conductor surfaces will normally form nonuniform E-fields possessing a breakdown behaviour determined by both the surface electric field and the rate of decay of the field. Besides that, among other issues, one has to take into account the type of gas, the temperature and the pressure. Therefore it seems important to apply an accurate onset criteria in corona onset design. This work presents the first step of a validated onset criteria useful for practical electrode geometries. This is accomplished for atmospheric air on the basis of the well-known Townsend approach for nonuniform fields with modifications concerning the gas parameters and validation against IEC 52 sphere-sphere gap breakdown voltages. It was found that the onset/breakdown voltage for medium nonuniform fields can be calculated by means of the same criteria for varying electrode curvatures and degrees of field utilization with an accuracy better than 4%.
{"title":"An improved model for the calculation of the electrical onset in gas insulated medium inhomogeneous gaps","authors":"C. Bak, B. Bak‐Jensen, J. T. Sørensen","doi":"10.1109/ELINSL.2002.995963","DOIUrl":"https://doi.org/10.1109/ELINSL.2002.995963","url":null,"abstract":"Most hardware for use in HV systems requires a thorough geometric design concerning the inception of breakdown (partial discharges, corona). Work shows an interest in such corona onset design optimization criteria. Corona onset optimization is based on numerical E-field calculations and different methods for determination of onset/no onset. Practical HV equipment conductor surfaces will normally form nonuniform E-fields possessing a breakdown behaviour determined by both the surface electric field and the rate of decay of the field. Besides that, among other issues, one has to take into account the type of gas, the temperature and the pressure. Therefore it seems important to apply an accurate onset criteria in corona onset design. This work presents the first step of a validated onset criteria useful for practical electrode geometries. This is accomplished for atmospheric air on the basis of the well-known Townsend approach for nonuniform fields with modifications concerning the gas parameters and validation against IEC 52 sphere-sphere gap breakdown voltages. It was found that the onset/breakdown voltage for medium nonuniform fields can be calculated by means of the same criteria for varying electrode curvatures and degrees of field utilization with an accuracy better than 4%.","PeriodicalId":10532,"journal":{"name":"Conference Record of the the 2002 IEEE International Symposium on Electrical Insulation (Cat. No.02CH37316)","volume":"25 1","pages":"411-416"},"PeriodicalIF":0.0,"publicationDate":"2002-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74220990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-04-07DOI: 10.1109/ELINSL.2002.995871
YongJun Kim, D. Kang, D. Hwang, Doh-Young Park
A novel sensor called CGVPI (Coupler for Global VPI) has been developed for simple mounting on Global VPI surface of small rotating machines without deterioration of insulation system. Even for large rotating machines of individual VPI insulation, CGVPI can be a cost effective option by tremendously reducing the sensor installation process. This paper describes the laboratory test results of the sensor. In addition, the on-line partial discharge sensor called Ceramic Coupler is introduced.
为了在不破坏绝缘系统的前提下，简单地安装在小型旋转机械的全局VPI表面，研制了一种新型传感器CGVPI (Coupler for Global VPI)。即使对于单个VPI绝缘的大型旋转机器，CGVPI也可以通过大大减少传感器安装过程而成为一种具有成本效益的选择。本文介绍了该传感器的实验室测试结果。此外，还介绍了在线局部放电传感器陶瓷耦合器。
{"title":"A partial discharge coupler for global VPI (CGVPI) rotating machines","authors":"YongJun Kim, D. Kang, D. Hwang, Doh-Young Park","doi":"10.1109/ELINSL.2002.995871","DOIUrl":"https://doi.org/10.1109/ELINSL.2002.995871","url":null,"abstract":"A novel sensor called CGVPI (Coupler for Global VPI) has been developed for simple mounting on Global VPI surface of small rotating machines without deterioration of insulation system. Even for large rotating machines of individual VPI insulation, CGVPI can be a cost effective option by tremendously reducing the sensor installation process. This paper describes the laboratory test results of the sensor. In addition, the on-line partial discharge sensor called Ceramic Coupler is introduced.","PeriodicalId":10532,"journal":{"name":"Conference Record of the the 2002 IEEE International Symposium on Electrical Insulation (Cat. No.02CH37316)","volume":"27 1","pages":"19-22"},"PeriodicalIF":0.0,"publicationDate":"2002-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83385695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-04-07DOI: 10.1109/ELINSL.2002.995995
S. Brettschneider, E. Lemke, J. L. Hinkle, M. Schneider
The paper reports on service field experiences with PD diagnostics on distribution cables using damped oscillating voltage waveforms: This test method was introduced some years ago in particular for on-site tests. Standard test procedures using continuous AC voltages are very cost intensive due to the high capacitive power demand of the cables and the resulting large sizes of the test sets, whereas other alternative methods do not reproduce similar PD than under service conditions. Experiences from the service field reveal that the oscillating voltage waveforms (OVW) method shows a very high sensitivity of PD detection and recognition of electrical treeing. Examples for critical assessment values have been determined for cross linked polyethylene (XLPE) cables as well as for oil-paper (PILC) cables allowing the network operator to decide which maintenance operation has to be performed on the distribution cable.
{"title":"Recent field experience in PD assessment of power cables using oscillating voltage waveforms","authors":"S. Brettschneider, E. Lemke, J. L. Hinkle, M. Schneider","doi":"10.1109/ELINSL.2002.995995","DOIUrl":"https://doi.org/10.1109/ELINSL.2002.995995","url":null,"abstract":"The paper reports on service field experiences with PD diagnostics on distribution cables using damped oscillating voltage waveforms: This test method was introduced some years ago in particular for on-site tests. Standard test procedures using continuous AC voltages are very cost intensive due to the high capacitive power demand of the cables and the resulting large sizes of the test sets, whereas other alternative methods do not reproduce similar PD than under service conditions. Experiences from the service field reveal that the oscillating voltage waveforms (OVW) method shows a very high sensitivity of PD detection and recognition of electrical treeing. Examples for critical assessment values have been determined for cross linked polyethylene (XLPE) cables as well as for oil-paper (PILC) cables allowing the network operator to decide which maintenance operation has to be performed on the distribution cable.","PeriodicalId":10532,"journal":{"name":"Conference Record of the the 2002 IEEE International Symposium on Electrical Insulation (Cat. No.02CH37316)","volume":"86 1","pages":"546-552"},"PeriodicalIF":0.0,"publicationDate":"2002-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77682886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-04-07DOI: 10.1109/ELINSL.2002.995939
X. Qi, S. Boggs
M.M. Perlmann (1989) has published models for conduction with "traps" (potential wells in the range of 0.8 eV) and with a combination of "traps" and "hopping sites" (potential wells in the range of 0.3 eV). However, the model for the latter does not extrapolate into the former as the number of hopping sites goes to zero. As a result, the conductivity cannot be computed for arbitrary densities of traps and hopping sites. A model has been developed based on quantum tunneling between the nearest neighbor and next nearest neighbor "traps" and "hopping sites" to calculate the hopping-induced conductivity, especially at high electric fields. The results are compared with Perlman's data.
{"title":"Model for high field conduction in doped polymers","authors":"X. Qi, S. Boggs","doi":"10.1109/ELINSL.2002.995939","DOIUrl":"https://doi.org/10.1109/ELINSL.2002.995939","url":null,"abstract":"M.M. Perlmann (1989) has published models for conduction with \"traps\" (potential wells in the range of 0.8 eV) and with a combination of \"traps\" and \"hopping sites\" (potential wells in the range of 0.3 eV). However, the model for the latter does not extrapolate into the former as the number of hopping sites goes to zero. As a result, the conductivity cannot be computed for arbitrary densities of traps and hopping sites. A model has been developed based on quantum tunneling between the nearest neighbor and next nearest neighbor \"traps\" and \"hopping sites\" to calculate the hopping-induced conductivity, especially at high electric fields. The results are compared with Perlman's data.","PeriodicalId":10532,"journal":{"name":"Conference Record of the the 2002 IEEE International Symposium on Electrical Insulation (Cat. No.02CH37316)","volume":"23 1","pages":"313-316"},"PeriodicalIF":0.0,"publicationDate":"2002-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78580694","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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