Pub Date : 2017-10-01DOI: 10.1109/INTLEC.2017.8214182
S. Bolte, Jehan Khan Afridi, J. Böcker
DC-DC converters with wide-bandgap semiconductors facilitate the operation at higher switching frequencies. Thus, inductors can be reduced in size which is beneficial in regard to power density and weight of the converter. As a drawback, high frequency inductors suffer from considerably large winding losses caused by skin and proximity effects. Litz wire is a possible solution but it results in a poor copper fill factor. Therefore, this paper discusses a mixed winding consisting of litz and solid wires in parallel. By means of calorimetric measurement it was shown that the winding losses can be reduced up to 9.8% with this solution.
{"title":"Winding concepts for high frequency inductors with reduced DC resistance","authors":"S. Bolte, Jehan Khan Afridi, J. Böcker","doi":"10.1109/INTLEC.2017.8214182","DOIUrl":"https://doi.org/10.1109/INTLEC.2017.8214182","url":null,"abstract":"DC-DC converters with wide-bandgap semiconductors facilitate the operation at higher switching frequencies. Thus, inductors can be reduced in size which is beneficial in regard to power density and weight of the converter. As a drawback, high frequency inductors suffer from considerably large winding losses caused by skin and proximity effects. Litz wire is a possible solution but it results in a poor copper fill factor. Therefore, this paper discusses a mixed winding consisting of litz and solid wires in parallel. By means of calorimetric measurement it was shown that the winding losses can be reduced up to 9.8% with this solution.","PeriodicalId":366207,"journal":{"name":"2017 IEEE International Telecommunications Energy Conference (INTELEC)","volume":"5 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127612037","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 : 2017-10-01DOI: 10.1109/INTLEC.2017.8214154
Yuan-sheng Huang
The lithium-ion battery has been gradually used in telecom industry as its outstanding cycle performance, large charge and discharge current, high energy density and so on. However, the expensive cost of lithium-ion battery is still the big trouble for telecom operators in the context of spending cuts. This paper introduces an innovative lithium-ion battery and lead-acid battery hybrid solution to solve the issue that operators need high performance battery and long backup time in frequent grid-off region. Compared with pure lithium-ion battery or traditional diesel generator power solution, the lithium-ion battery and lead-acid battery hybrid solution has better economy to help operators reduce investment and OPEX.
{"title":"An Innovative lithium-ion battery and lead-acid battery hybrid solution for telecom in frequent grid off region","authors":"Yuan-sheng Huang","doi":"10.1109/INTLEC.2017.8214154","DOIUrl":"https://doi.org/10.1109/INTLEC.2017.8214154","url":null,"abstract":"The lithium-ion battery has been gradually used in telecom industry as its outstanding cycle performance, large charge and discharge current, high energy density and so on. However, the expensive cost of lithium-ion battery is still the big trouble for telecom operators in the context of spending cuts. This paper introduces an innovative lithium-ion battery and lead-acid battery hybrid solution to solve the issue that operators need high performance battery and long backup time in frequent grid-off region. Compared with pure lithium-ion battery or traditional diesel generator power solution, the lithium-ion battery and lead-acid battery hybrid solution has better economy to help operators reduce investment and OPEX.","PeriodicalId":366207,"journal":{"name":"2017 IEEE International Telecommunications Energy Conference (INTELEC)","volume":"348 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134325330","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 : 2017-10-01DOI: 10.1109/INTLEC.2017.8214125
Naomichi Nakamura, F. Mahmood, Ken Okamoto, Y. Okugawa, Y. Akiyama
Recently, lighting equipment using inverter control and light emitting diode (LED) has been used in machine rooms in telecommunication centers and data centers to save energy. However, LED lighting equipment is known to generate harmful levels of electromagnetic transient disturbances (in particular, transient currents in power lines) to ICT equipment [1]. CISPR 15 [2], the international standard for electromagnetic disturbances from lighting equipment, defines a measurement method and limit level for continuous electromagnetic disturbance, but does not specify a measurement method or limit level for transient currents. We propose a measurement method to evaluate the peak level of transient currents from LED lighting equipment in a representative actual-use environment. This method, using a phase control switch, a power network impedance (PNI) compensation circuit, a PNI artificial circuit, a current probe and an oscilloscope, can avoid dependence on test sites, and enable highly reproducible measurements. We optimized the parameters of the PNI compensation circuit by circuit simulation, and the PNI artificial circuit by measurement. It was found that the proposed method enables highly reproducible measurement of transient currents from LED lighting equipment, thus avoiding dependence on test sites.
{"title":"A study on measurement method for transient current from lighting equipment with considering the dependence on test sites","authors":"Naomichi Nakamura, F. Mahmood, Ken Okamoto, Y. Okugawa, Y. Akiyama","doi":"10.1109/INTLEC.2017.8214125","DOIUrl":"https://doi.org/10.1109/INTLEC.2017.8214125","url":null,"abstract":"Recently, lighting equipment using inverter control and light emitting diode (LED) has been used in machine rooms in telecommunication centers and data centers to save energy. However, LED lighting equipment is known to generate harmful levels of electromagnetic transient disturbances (in particular, transient currents in power lines) to ICT equipment [1]. CISPR 15 [2], the international standard for electromagnetic disturbances from lighting equipment, defines a measurement method and limit level for continuous electromagnetic disturbance, but does not specify a measurement method or limit level for transient currents. We propose a measurement method to evaluate the peak level of transient currents from LED lighting equipment in a representative actual-use environment. This method, using a phase control switch, a power network impedance (PNI) compensation circuit, a PNI artificial circuit, a current probe and an oscilloscope, can avoid dependence on test sites, and enable highly reproducible measurements. We optimized the parameters of the PNI compensation circuit by circuit simulation, and the PNI artificial circuit by measurement. It was found that the proposed method enables highly reproducible measurement of transient currents from LED lighting equipment, thus avoiding dependence on test sites.","PeriodicalId":366207,"journal":{"name":"2017 IEEE International Telecommunications Energy Conference (INTELEC)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125936491","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 : 2017-10-01DOI: 10.1109/INTLEC.2017.8214204
Kosuke Sasakura, Takeshi Aoki, Takeshi Watanabe
Data Centers (DCs) are becoming increasingly important in recent years and require efficient operation and management. Thus, a topic of focus has been DC Infrastructure Management (DCIM) that can manage ICT equipment, power equipment, HVAC systems, etc. In this study, we developed a method to design the ICT equipment layout in the server room by using DCIM and Computer Fluid Dynamics (CFD). The method's effectiveness was evaluated and its ability to achieve efficient data center operation and management was validated.
{"title":"Study on Data Center Optimal Management by utilizing Data Center Infrastructure Management","authors":"Kosuke Sasakura, Takeshi Aoki, Takeshi Watanabe","doi":"10.1109/INTLEC.2017.8214204","DOIUrl":"https://doi.org/10.1109/INTLEC.2017.8214204","url":null,"abstract":"Data Centers (DCs) are becoming increasingly important in recent years and require efficient operation and management. Thus, a topic of focus has been DC Infrastructure Management (DCIM) that can manage ICT equipment, power equipment, HVAC systems, etc. In this study, we developed a method to design the ICT equipment layout in the server room by using DCIM and Computer Fluid Dynamics (CFD). The method's effectiveness was evaluated and its ability to achieve efficient data center operation and management was validated.","PeriodicalId":366207,"journal":{"name":"2017 IEEE International Telecommunications Energy Conference (INTELEC)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125078025","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 : 2017-10-01DOI: 10.1109/INTLEC.2017.8211685
Leo Saro, Clemente Zanettin, Vinko Božič
A modular UPS system is generally presented as having a much higher level of availability than a monolithic, double conversion, on-line UPS system. However, there are different types of modular UPS systems available on the market, with varying degrees of reliability and availability. To represent the strengths and weaknesses of each architecture and accurately compare them to one another, a detailed reliability model must be built. This paper presents a rational methodology to define and analyse each modular UPS system, and to identify its mode of operation and possible failure conditions. This methodology is then applied to the most common modular UPS architectures present on the market, highlighting the advantages and disadvantages of each, and making the differentiation between ordinary, good and excellent modular UPS system designs possible.
{"title":"Reliability analysis and calculation for the most common modular UPS system architectures","authors":"Leo Saro, Clemente Zanettin, Vinko Božič","doi":"10.1109/INTLEC.2017.8211685","DOIUrl":"https://doi.org/10.1109/INTLEC.2017.8211685","url":null,"abstract":"A modular UPS system is generally presented as having a much higher level of availability than a monolithic, double conversion, on-line UPS system. However, there are different types of modular UPS systems available on the market, with varying degrees of reliability and availability. To represent the strengths and weaknesses of each architecture and accurately compare them to one another, a detailed reliability model must be built. This paper presents a rational methodology to define and analyse each modular UPS system, and to identify its mode of operation and possible failure conditions. This methodology is then applied to the most common modular UPS architectures present on the market, highlighting the advantages and disadvantages of each, and making the differentiation between ordinary, good and excellent modular UPS system designs possible.","PeriodicalId":366207,"journal":{"name":"2017 IEEE International Telecommunications Energy Conference (INTELEC)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123784200","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 : 2017-10-01DOI: 10.1109/INTLEC.2017.8214151
Yuan-sheng Huang
Lead-acid battery has been widely used as a standby power for telecom industry. As the different electrical characteristic of battery among different categories, even battery banks of same category and same manufacture but different serving age, they can't be directly used in parallel connection, or it will bring disastrous consequences, including fewer discharge capacity, shorter battery life. This rule leads to trouble for existing lead-acid battery utilization during telecom base station expansion. Operators should pay much more money for the new larger capacity of lead-acid battery, then existing battery is replaced and abandoned, it's not environmental too. This paper introduces an innovative hybrid battery management system to solve the issue that old battery banks can't be reused with new battery banks during site expansion. It can help operators to realize low TCO, high reliability of power supply, and best cost performance. The hybrid battery management system supports managing the new and old two categories of lead-acid battery banks with same or different rated capacity. Especially, it also supports the hybrid application of lithium battery and lead-acid battery though upgrading the software.
{"title":"An innovative hybrid battery management system for telecom","authors":"Yuan-sheng Huang","doi":"10.1109/INTLEC.2017.8214151","DOIUrl":"https://doi.org/10.1109/INTLEC.2017.8214151","url":null,"abstract":"Lead-acid battery has been widely used as a standby power for telecom industry. As the different electrical characteristic of battery among different categories, even battery banks of same category and same manufacture but different serving age, they can't be directly used in parallel connection, or it will bring disastrous consequences, including fewer discharge capacity, shorter battery life. This rule leads to trouble for existing lead-acid battery utilization during telecom base station expansion. Operators should pay much more money for the new larger capacity of lead-acid battery, then existing battery is replaced and abandoned, it's not environmental too. This paper introduces an innovative hybrid battery management system to solve the issue that old battery banks can't be reused with new battery banks during site expansion. It can help operators to realize low TCO, high reliability of power supply, and best cost performance. The hybrid battery management system supports managing the new and old two categories of lead-acid battery banks with same or different rated capacity. Especially, it also supports the hybrid application of lithium battery and lead-acid battery though upgrading the software.","PeriodicalId":366207,"journal":{"name":"2017 IEEE International Telecommunications Energy Conference (INTELEC)","volume":"153 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127421144","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 : 2017-10-01DOI: 10.1109/INTLEC.2017.8214138
N. Grass, Anja Woelfel
The transition from centralized grid control towards distributed and cellular control requires new methods and intelligent solutions for power generation, storage and transmission. Due to temporary occurrence of reversed power flow during low load conditions in distribution grids, the grid voltage may reach or may exceed voltage limits. Data centers and telecom facilities, which are equipped with batteries, generation units and power electronic grid interfaces are highly appropriate to offer services to the grid operators to solve this problem. One possible option to keep grid voltages within the limits is the transmission of reactive power over critical grid lines, generated at the connection points of renewable sources. Additionally, reactive power sources need to be provided at transformer stations to avoid additional reactive power flow towards the MV grid. The paper shows results of an ongoing research project, where four partners cooperate to demonstrate the effects and the automatic voltage optimization in a real existing low voltage grid. Research partners are Technische Hochschule Esslingen, KBR Kompensationsanlagenbau GmbH, Schwabach and VWEW-Energie, Kaufbeuren. The equipment has already been installed into the grid and is currently operated in the test phase.
{"title":"Optimization-algorithm addressing voltage and power quality in distributed grid control systems","authors":"N. Grass, Anja Woelfel","doi":"10.1109/INTLEC.2017.8214138","DOIUrl":"https://doi.org/10.1109/INTLEC.2017.8214138","url":null,"abstract":"The transition from centralized grid control towards distributed and cellular control requires new methods and intelligent solutions for power generation, storage and transmission. Due to temporary occurrence of reversed power flow during low load conditions in distribution grids, the grid voltage may reach or may exceed voltage limits. Data centers and telecom facilities, which are equipped with batteries, generation units and power electronic grid interfaces are highly appropriate to offer services to the grid operators to solve this problem. One possible option to keep grid voltages within the limits is the transmission of reactive power over critical grid lines, generated at the connection points of renewable sources. Additionally, reactive power sources need to be provided at transformer stations to avoid additional reactive power flow towards the MV grid. The paper shows results of an ongoing research project, where four partners cooperate to demonstrate the effects and the automatic voltage optimization in a real existing low voltage grid. Research partners are Technische Hochschule Esslingen, KBR Kompensationsanlagenbau GmbH, Schwabach and VWEW-Energie, Kaufbeuren. The equipment has already been installed into the grid and is currently operated in the test phase.","PeriodicalId":366207,"journal":{"name":"2017 IEEE International Telecommunications Energy Conference (INTELEC)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130620723","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 : 2017-10-01DOI: 10.1109/INTLEC.2017.8214172
Javad Khodabakhsh, P. Prabhu, G. Moschopoulos
Single stage power factor corrected (SSPFC) AC-DC converters are popular in industrial applications such as telecom because they are cheaper and smaller than conventional two-stage converters. The intermediate DC bus voltage of these converters, however, varies significantly when used in universal voltage range applications. A new AC-DC SSPFC resonant converter that can be operated with universal input line voltage and significantly reduced DC bus voltage variation is proposed in the paper. In the paper, the operation of the new converter is explained, its stead state operation is analyzed, and the design of the converter is discussed and demonstrated with a design example. The feasibility of the converter is confirmed with results obtained from a prototype converter.
{"title":"Analysis and design of AC-DC resonant single-stage converter with reduced DC bus voltage variation","authors":"Javad Khodabakhsh, P. Prabhu, G. Moschopoulos","doi":"10.1109/INTLEC.2017.8214172","DOIUrl":"https://doi.org/10.1109/INTLEC.2017.8214172","url":null,"abstract":"Single stage power factor corrected (SSPFC) AC-DC converters are popular in industrial applications such as telecom because they are cheaper and smaller than conventional two-stage converters. The intermediate DC bus voltage of these converters, however, varies significantly when used in universal voltage range applications. A new AC-DC SSPFC resonant converter that can be operated with universal input line voltage and significantly reduced DC bus voltage variation is proposed in the paper. In the paper, the operation of the new converter is explained, its stead state operation is analyzed, and the design of the converter is discussed and demonstrated with a design example. The feasibility of the converter is confirmed with results obtained from a prototype converter.","PeriodicalId":366207,"journal":{"name":"2017 IEEE International Telecommunications Energy Conference (INTELEC)","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116630673","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 : 2017-10-01DOI: 10.1109/INTLEC.2017.8214135
M. Yong, D. Bettle
As the demand for data increase and the need for higher density network load, greater resiliency and efficiency a need for a reliable power distribution and back up is required. Currently our −48VDC distribution has limitation in size (kW), length of cable run and large battery reserves. Higher Voltage DC offers a number of benefits for Telstra from reduced cable size, simplified distribution set up without need for synchronization and switching, reduced battery reserves and the ability to match network and thermal load. From a Telcos perspective, power topologies using HVDC become viable when the total cost of ownership is less than persevering with −48VDC architecture and accepted the expected rate of outages (and consequential financial impact) that comes with it. This paper explores the practical and financial benefits of HVDC architecture, and whether it is financially viable for Telcos today even if non-HVDC native loads are the norm and require extra power conversion.
{"title":"Deploying ‘HVDC’ in existing network exchanges practical and financial benefits for telecommunications carriers","authors":"M. Yong, D. Bettle","doi":"10.1109/INTLEC.2017.8214135","DOIUrl":"https://doi.org/10.1109/INTLEC.2017.8214135","url":null,"abstract":"As the demand for data increase and the need for higher density network load, greater resiliency and efficiency a need for a reliable power distribution and back up is required. Currently our −48VDC distribution has limitation in size (kW), length of cable run and large battery reserves. Higher Voltage DC offers a number of benefits for Telstra from reduced cable size, simplified distribution set up without need for synchronization and switching, reduced battery reserves and the ability to match network and thermal load. From a Telcos perspective, power topologies using HVDC become viable when the total cost of ownership is less than persevering with −48VDC architecture and accepted the expected rate of outages (and consequential financial impact) that comes with it. This paper explores the practical and financial benefits of HVDC architecture, and whether it is financially viable for Telcos today even if non-HVDC native loads are the norm and require extra power conversion.","PeriodicalId":366207,"journal":{"name":"2017 IEEE International Telecommunications Energy Conference (INTELEC)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117216243","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 : 2017-10-01DOI: 10.1109/INTLEC.2017.8214158
Bernd Wunder, L. Ott, Julian Kaiser, Kilian Gosses, Matthias Schulz, Fabian Fersterra, M. März, M. Lavery, Yunchao Han
A dc-based low-voltage power supply offers many advantages over the historically grown ac voltage infrastructure. The paper shows the potentials for cost reduction, efficiency enhancement and equipment miniaturization through new cognitive power electronics, but also discusses the obstacles to a faster market penetration of dc microgrids. These include aspects of grid control, grid stability, security and safety. As a main challenge the arc phenomena in connectors will be discussed, which affects all mechanical connectors in a dc grid installation.
{"title":"Droop controlled cognitive power electronics for DC microgrids","authors":"Bernd Wunder, L. Ott, Julian Kaiser, Kilian Gosses, Matthias Schulz, Fabian Fersterra, M. März, M. Lavery, Yunchao Han","doi":"10.1109/INTLEC.2017.8214158","DOIUrl":"https://doi.org/10.1109/INTLEC.2017.8214158","url":null,"abstract":"A dc-based low-voltage power supply offers many advantages over the historically grown ac voltage infrastructure. The paper shows the potentials for cost reduction, efficiency enhancement and equipment miniaturization through new cognitive power electronics, but also discusses the obstacles to a faster market penetration of dc microgrids. These include aspects of grid control, grid stability, security and safety. As a main challenge the arc phenomena in connectors will be discussed, which affects all mechanical connectors in a dc grid installation.","PeriodicalId":366207,"journal":{"name":"2017 IEEE International Telecommunications Energy Conference (INTELEC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130991167","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：