Pub Date : 2006-09-01DOI: 10.1109/DEIV.2006.357243
O. Yamamoto, H. Hayashi, T. Satoh, S. Hamada, T. Kobayashi, H. Omura, H. Morii
In our previous studies, with a comparatively short cylindrical insulator of 10 mm length, we have found that the charging process due to ac voltage excitation in vacuum is characterized by three different states; initiation, quasi-stable state and stable state. In all of the states, the insulator surface acquires positive charge irrespective of applied voltage amplitude or phase. Also, we have reported that the magnitude of the charge decreases with the roughness of insulator, and that this results in the improvement of surface insulation strength. To apply the above results for practical insulators used for vacuum valves of VCBs, we have investigated the characteristics for a longer insulator up to 50 mm made of borosilicate (Pyrexreg). As a result, we have confirmed that the charging process is basically the same as that observed in the previous studies. We have also confirmed the effectiveness of roughening the surface on reducing the charge magnitude and increasing the flashover voltage
{"title":"Flashover and Charging Characteristics of a Long Solid Insulator Exposed to ac Voltage in Vacuum","authors":"O. Yamamoto, H. Hayashi, T. Satoh, S. Hamada, T. Kobayashi, H. Omura, H. Morii","doi":"10.1109/DEIV.2006.357243","DOIUrl":"https://doi.org/10.1109/DEIV.2006.357243","url":null,"abstract":"In our previous studies, with a comparatively short cylindrical insulator of 10 mm length, we have found that the charging process due to ac voltage excitation in vacuum is characterized by three different states; initiation, quasi-stable state and stable state. In all of the states, the insulator surface acquires positive charge irrespective of applied voltage amplitude or phase. Also, we have reported that the magnitude of the charge decreases with the roughness of insulator, and that this results in the improvement of surface insulation strength. To apply the above results for practical insulators used for vacuum valves of VCBs, we have investigated the characteristics for a longer insulator up to 50 mm made of borosilicate (Pyrexreg). As a result, we have confirmed that the charging process is basically the same as that observed in the previous studies. We have also confirmed the effectiveness of roughening the surface on reducing the charge magnitude and increasing the flashover voltage","PeriodicalId":369861,"journal":{"name":"2006 International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116189806","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}
M. Ohnishi, H. Nozaki, H. Osawa, K. Minaki, K. Kitajima, K. Yokota
A negative potential is applied to an object in plasma consisting of methane or acetylene in order to coat a solid thin film such as DLC (diamond-like-carbon) on a material surface. The method is called plasma-based ion implantation (PBII). Since mechanical objects commonly possess complex shapes, it may be difficult to coat DLC on them in a uniform manner. This non-uniformity in thickness has been studied in many papers, and it has been reported that it is improved by applying a pulse potential repeatedly to the coated material. Using a scratch test, we studied the local adhesion of DLC coated by PBII to SUS304 thin plates attached at several places in a trench-shaped cathode. We found that the adhesion gets greater, in order, for the plates at the side, the bottom of the groove in a trench, and the top of a trench. In order to explain the results, further studies are required
{"title":"Local Adhesion of Diamond-Like Carbon Films Coated on Substrates in a Trench-shaped Cathode","authors":"M. Ohnishi, H. Nozaki, H. Osawa, K. Minaki, K. Kitajima, K. Yokota","doi":"10.3131/jvsj.50.328","DOIUrl":"https://doi.org/10.3131/jvsj.50.328","url":null,"abstract":"A negative potential is applied to an object in plasma consisting of methane or acetylene in order to coat a solid thin film such as DLC (diamond-like-carbon) on a material surface. The method is called plasma-based ion implantation (PBII). Since mechanical objects commonly possess complex shapes, it may be difficult to coat DLC on them in a uniform manner. This non-uniformity in thickness has been studied in many papers, and it has been reported that it is improved by applying a pulse potential repeatedly to the coated material. Using a scratch test, we studied the local adhesion of DLC coated by PBII to SUS304 thin plates attached at several places in a trench-shaped cathode. We found that the adhesion gets greater, in order, for the plates at the side, the bottom of the groove in a trench, and the top of a trench. In order to explain the results, further studies are required","PeriodicalId":369861,"journal":{"name":"2006 International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"404 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123000337","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 : 2006-09-01DOI: 10.1109/DEIV.2006.357289
Zhiyuan Liu, Z. Wang, Jimei Wang
This paper introduces a new slot type axial magnetic field (AMF) contact. It has lower resistance compared with its counterpart conventional one by introducing a contact bridge that substitutes for stainless steel support in conventional contact. There is a gap between the contact bridge and contact plate. In close position, the contact bridge is pressed on contact plate by contact force and coil deformation. So current goes through the contact bridge to reach contact plate directly. In an interruption operation, the gap restores with contact force disappearing, which pushes current passing through coils of the slot type AMF contact. So the same AMF can be generated as a conventional one. As a result, short circuit current interruption tests showed that the interrupting capacity of the vacuum interrupter with new contacts was not less than that with conventional contacts. Resistance of vacuum interrupter with conventional contact is 10-12 muOmega at contact force 2000N. It decreased to 7muOmega with the new contact
{"title":"A New Slot Type Axial Magnetic Field Contact with Low Resistance","authors":"Zhiyuan Liu, Z. Wang, Jimei Wang","doi":"10.1109/DEIV.2006.357289","DOIUrl":"https://doi.org/10.1109/DEIV.2006.357289","url":null,"abstract":"This paper introduces a new slot type axial magnetic field (AMF) contact. It has lower resistance compared with its counterpart conventional one by introducing a contact bridge that substitutes for stainless steel support in conventional contact. There is a gap between the contact bridge and contact plate. In close position, the contact bridge is pressed on contact plate by contact force and coil deformation. So current goes through the contact bridge to reach contact plate directly. In an interruption operation, the gap restores with contact force disappearing, which pushes current passing through coils of the slot type AMF contact. So the same AMF can be generated as a conventional one. As a result, short circuit current interruption tests showed that the interrupting capacity of the vacuum interrupter with new contacts was not less than that with conventional contacts. Resistance of vacuum interrupter with conventional contact is 10-12 muOmega at contact force 2000N. It decreased to 7muOmega with the new contact","PeriodicalId":369861,"journal":{"name":"2006 International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131265216","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 : 2006-09-01DOI: 10.1109/DEIV.2006.357350
Chunguang Hou, Jing Sun, Yundong Cao, Xiaoming Liu, Erzhi Wang
A novel permanent magnet actuator (PMA) for mining vacuum circuit breaker (VCB) is presented in this paper. Which is monostable, has two coils and able to break the VCB when the fault of low-voltage happened. And can detect the voltage variation in main circuit at each instant. When the fault of low-voltage happened, it can automatically break without additional detection and control of apparatus. Moreover, the different states and parameters of breaking and closing courses have been numerical computed and analyzed by adopting ANSOFT software. Based on the simulation results, the prototype is manufactured and assembled in the mining VCB. The feasibility and validity of the proposed PMA have been proved by testing results
{"title":"Design and Analyses on Permanent Magnet Actuator for Mining Vacuum Circuit Breaker","authors":"Chunguang Hou, Jing Sun, Yundong Cao, Xiaoming Liu, Erzhi Wang","doi":"10.1109/DEIV.2006.357350","DOIUrl":"https://doi.org/10.1109/DEIV.2006.357350","url":null,"abstract":"A novel permanent magnet actuator (PMA) for mining vacuum circuit breaker (VCB) is presented in this paper. Which is monostable, has two coils and able to break the VCB when the fault of low-voltage happened. And can detect the voltage variation in main circuit at each instant. When the fault of low-voltage happened, it can automatically break without additional detection and control of apparatus. Moreover, the different states and parameters of breaking and closing courses have been numerical computed and analyzed by adopting ANSOFT software. Based on the simulation results, the prototype is manufactured and assembled in the mining VCB. The feasibility and validity of the proposed PMA have been proved by testing results","PeriodicalId":369861,"journal":{"name":"2006 International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131765021","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 : 2006-09-01DOI: 10.1109/DEIV.2006.357225
A. Batrakov, D.J. Johnson, S. Onischenko, D. Proskurovsky
The paper is devoted to study of mechanisms responsible on vacuum breakdown as a whole and the total voltage effect in particular. Experiments at dc and pulsed voltages were carried out. It has been shown that there is no manifestation of the total voltage effect at dc voltages up to 20 kV. The strong dependence of hold-off on anode temperature was recognized at dc voltages while pulsed hold-off turned out to be almost the same with heating electrodes. This gives a basis to consider gas desorption as an insufficient factor in initiation of pulsed breakdown. An attempt to enhance hold-off with electrostatic removing of loosely bound particles with assistance of electron flow from a thermionic cathode was undertaken in the work. The approach tuned out to be ineffective
{"title":"Cathode and Anode Phenomena at Initiation of Pulsed Vacuum Breakdown","authors":"A. Batrakov, D.J. Johnson, S. Onischenko, D. Proskurovsky","doi":"10.1109/DEIV.2006.357225","DOIUrl":"https://doi.org/10.1109/DEIV.2006.357225","url":null,"abstract":"The paper is devoted to study of mechanisms responsible on vacuum breakdown as a whole and the total voltage effect in particular. Experiments at dc and pulsed voltages were carried out. It has been shown that there is no manifestation of the total voltage effect at dc voltages up to 20 kV. The strong dependence of hold-off on anode temperature was recognized at dc voltages while pulsed hold-off turned out to be almost the same with heating electrodes. This gives a basis to consider gas desorption as an insufficient factor in initiation of pulsed breakdown. An attempt to enhance hold-off with electrostatic removing of loosely bound particles with assistance of electron flow from a thermionic cathode was undertaken in the work. The approach tuned out to be ineffective","PeriodicalId":369861,"journal":{"name":"2006 International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133436215","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 : 2006-09-01DOI: 10.1109/DEIV.2006.357219
Y. Korolev, O. B. Frants, V. G. Geyman, R. V. Ivashov, V. N. Landl, I. A. Shemyakin
In this paper the electric strength recovery process in the pseudospark switch is investigated. The reasons which lead to pulse repetition rate limitation are analyzed. The electric schemes for frequency operation increasing are investigated
本文研究了假火花开关的电强度恢复过程。分析了造成脉冲重复率限制的原因。研究了提高运行频率的电气方案
{"title":"Investigation of the Electric Strength Recovery Process in the Pseudospark Switch with a High Pulse Repetition Rate","authors":"Y. Korolev, O. B. Frants, V. G. Geyman, R. V. Ivashov, V. N. Landl, I. A. Shemyakin","doi":"10.1109/DEIV.2006.357219","DOIUrl":"https://doi.org/10.1109/DEIV.2006.357219","url":null,"abstract":"In this paper the electric strength recovery process in the pseudospark switch is investigated. The reasons which lead to pulse repetition rate limitation are analyzed. The electric schemes for frequency operation increasing are investigated","PeriodicalId":369861,"journal":{"name":"2006 International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133625880","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 : 2006-09-01DOI: 10.1109/DEIV.2006.357356
J. Langner, M. Sadowski, P. Strzyzewski, R. Mirowski, J. Witkowski, S. Tazzari, L. Catani, A. Cianchi, J. Lorkiewicz, Roberto Russo, T. Paryjczak, J. Rogowski, J. Sekutowicz
The paper reports on recent progress in the application of the UHV arc technology, which was proposed as an alternative solution for the deposition of thin superconducting films of pure niobium (Nb) upon the inner surfaces of RF cavities designed for particle accelerators. There are presented new experimental studies aimed at the deposition of superconducting films of pure niobium (Nb) and lead (Pb) needed for the modern accelerator technology. The main experimental results and characteristics of arc-deposited thin superconducting films are discussed, and the progress achieved recently in the formation of such films is presented
{"title":"Progress in Use of Ultra-High Vacuum Cathodic Arcs for Deposition of Thin Film Superconducting Layers","authors":"J. Langner, M. Sadowski, P. Strzyzewski, R. Mirowski, J. Witkowski, S. Tazzari, L. Catani, A. Cianchi, J. Lorkiewicz, Roberto Russo, T. Paryjczak, J. Rogowski, J. Sekutowicz","doi":"10.1109/DEIV.2006.357356","DOIUrl":"https://doi.org/10.1109/DEIV.2006.357356","url":null,"abstract":"The paper reports on recent progress in the application of the UHV arc technology, which was proposed as an alternative solution for the deposition of thin superconducting films of pure niobium (Nb) upon the inner surfaces of RF cavities designed for particle accelerators. There are presented new experimental studies aimed at the deposition of superconducting films of pure niobium (Nb) and lead (Pb) needed for the modern accelerator technology. The main experimental results and characteristics of arc-deposited thin superconducting films are discussed, and the progress achieved recently in the formation of such films is presented","PeriodicalId":369861,"journal":{"name":"2006 International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"174 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134118238","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 : 2006-09-01DOI: 10.1109/DEIV.2006.357342
Yuesheng Zheng, Zhongyi Wang, Zhiyuan Liu, Mengmeng Hao, Jimei Wang
Magnetic field characteristics of vacuum interrupter with cup type axial magnetic field (AMF) contacts where an iron ring is introduced are investigated by three dimensions finite element method. The results show that 1) Axial magnetic flux density at current peak increases greatly on iron area, while it decreases slightly on center area. With increase of gap distance, AMF keeps unchanged on non-iron area, while it decreases greatly on iron area. 2) Axial magnetic flux density at current zero increases greatly on iron area. With increase of gap distance, it decreases greatly. Influence of irons on AMF only takes place on iron area. 3) Phase shift time between AMF and source current becomes higher all over the contact area including iron area and non-iron area
{"title":"Influence of Irons on Magnetic Field Characteristics of Vacuum Interrupter with Cup type Axial Magnetic Field Contacts","authors":"Yuesheng Zheng, Zhongyi Wang, Zhiyuan Liu, Mengmeng Hao, Jimei Wang","doi":"10.1109/DEIV.2006.357342","DOIUrl":"https://doi.org/10.1109/DEIV.2006.357342","url":null,"abstract":"Magnetic field characteristics of vacuum interrupter with cup type axial magnetic field (AMF) contacts where an iron ring is introduced are investigated by three dimensions finite element method. The results show that 1) Axial magnetic flux density at current peak increases greatly on iron area, while it decreases slightly on center area. With increase of gap distance, AMF keeps unchanged on non-iron area, while it decreases greatly on iron area. 2) Axial magnetic flux density at current zero increases greatly on iron area. With increase of gap distance, it decreases greatly. Influence of irons on AMF only takes place on iron area. 3) Phase shift time between AMF and source current becomes higher all over the contact area including iron area and non-iron area","PeriodicalId":369861,"journal":{"name":"2006 International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115216581","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 : 2006-09-01DOI: 10.1109/DEIV.2006.357216
G. Sandolache, S. Rowe
The presence of molten metal on the surface of the electrodes of vacuum circuit breakers, following the interruption of high currents, is a potential source of reduction of breakdown strength. The authors thus devised special experiments to study this effect by separating the roles of the presence of the metal vapour from that of the presence of a molten metal. The experiments also separate the pure dielectric effect from that of the post arc plasma sheath and its dynamic movement, under the influence of the transient recovery voltage, TRV. The results show clearly the large reduction of breakdown voltage which can occur in under these circumstances. These results allow an improved understanding of the physical mechanisms taking place under the transient plasma sheath during the TRV
{"title":"Vacuum Breakdown between Molten Metal Electrodes","authors":"G. Sandolache, S. Rowe","doi":"10.1109/DEIV.2006.357216","DOIUrl":"https://doi.org/10.1109/DEIV.2006.357216","url":null,"abstract":"The presence of molten metal on the surface of the electrodes of vacuum circuit breakers, following the interruption of high currents, is a potential source of reduction of breakdown strength. The authors thus devised special experiments to study this effect by separating the roles of the presence of the metal vapour from that of the presence of a molten metal. The experiments also separate the pure dielectric effect from that of the post arc plasma sheath and its dynamic movement, under the influence of the transient recovery voltage, TRV. The results show clearly the large reduction of breakdown voltage which can occur in under these circumstances. These results allow an improved understanding of the physical mechanisms taking place under the transient plasma sheath during the TRV","PeriodicalId":369861,"journal":{"name":"2006 International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114370553","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 : 2006-09-01DOI: 10.1109/DEIV.2006.357335
A. Chaly, I. N. Poluyanova
An analysis of switching processes at interruption of lightly loaded urban and rural networks with the aid of VCB has been provided. It has been found that typical loading of the distribution feeders result in virtual absence of recovery voltage shift being the main reason for non-sustained disruptive discharges (NSDD). Truly unloaded situation is interruption of section located between neighbouring points of isolation in cable line, but 95% of lengths of these sections are less than 3km that is substantially shorter than ~50km lengths considered by standard. This difference results in different duration of current pulses relevant for VCB closing in real and test cases. Estimation of the probability of contact micro welding has shown that in real case probability of contact welding is much lowers which results in lower probability of NSDD. On the basis of the above irrelevancy of the current IEC requirement with regard to general purpose VCB has been stated. Alternative test procedure for special purpose VCB has also been offered
{"title":"Relevancy of IEC Requirements Related to Switching Cable and Line Charging Currents for Medium Voltage Vacuum Circuit Breakers (VCB)","authors":"A. Chaly, I. N. Poluyanova","doi":"10.1109/DEIV.2006.357335","DOIUrl":"https://doi.org/10.1109/DEIV.2006.357335","url":null,"abstract":"An analysis of switching processes at interruption of lightly loaded urban and rural networks with the aid of VCB has been provided. It has been found that typical loading of the distribution feeders result in virtual absence of recovery voltage shift being the main reason for non-sustained disruptive discharges (NSDD). Truly unloaded situation is interruption of section located between neighbouring points of isolation in cable line, but 95% of lengths of these sections are less than 3km that is substantially shorter than ~50km lengths considered by standard. This difference results in different duration of current pulses relevant for VCB closing in real and test cases. Estimation of the probability of contact micro welding has shown that in real case probability of contact welding is much lowers which results in lower probability of NSDD. On the basis of the above irrelevancy of the current IEC requirement with regard to general purpose VCB has been stated. Alternative test procedure for special purpose VCB has also been offered","PeriodicalId":369861,"journal":{"name":"2006 International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"249 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124721452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：