Pub Date : 2014-10-23DOI: 10.1109/UPEC.2014.6934632
Krisztina Vezer, A. Ceclan, L. Czumbil
The paper presents an integrative approach of energy efficiency solutions proposed for a building belonging to the Technical University of Cluj-Napoca. These efficiency measures were proposed by an interdisciplinary academic research team, committed to empower the university energy efficiency, so as to contribute to the welfare of society and also raise awareness on the importance and potential that lays in buildings in respect energy efficiency. Besides energy cuts, behavioral change and environmental benefits, a detailed financial assessment revealed that investment in these solutions is also feasible and profitable.
{"title":"EMpower university efficiency. Solutions investigation within the buildings of technical university of Cluj-Napoca","authors":"Krisztina Vezer, A. Ceclan, L. Czumbil","doi":"10.1109/UPEC.2014.6934632","DOIUrl":"https://doi.org/10.1109/UPEC.2014.6934632","url":null,"abstract":"The paper presents an integrative approach of energy efficiency solutions proposed for a building belonging to the Technical University of Cluj-Napoca. These efficiency measures were proposed by an interdisciplinary academic research team, committed to empower the university energy efficiency, so as to contribute to the welfare of society and also raise awareness on the importance and potential that lays in buildings in respect energy efficiency. Besides energy cuts, behavioral change and environmental benefits, a detailed financial assessment revealed that investment in these solutions is also feasible and profitable.","PeriodicalId":414838,"journal":{"name":"2014 49th International Universities Power Engineering Conference (UPEC)","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116735470","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 : 2014-10-23DOI: 10.1109/UPEC.2014.6934629
Juniku Matsuura, K. Kawahara, Zoka Yoshifumi
In recent years, a photovoltaic solar energy system has widely spread on residential areas as an alternative energy of a fossil fuel. Since the output of photovoltaic (PV) cell sharply changes according to weather conditions, a certain power storage device is required to smooth the output and to meet electricity demand equivalent to a household load. Such devices are effective also a backup power at the time of a disaster like the Great East Japan Earthquake. A fuel cell (FC) is a promising candidate for long term energy system because hydrogen is supplied stably. We have so far proposed a hybrid system of PV and FC in residential use. The proposed system is consists of PV array, FC stack, electrolyzer (EL), hydrogen storage tank, and power conversion devices. This paper deals with a mixed integer programming problem for determining the amount of hydrogen flow and hydrogen remaining amount in the storage tank. We verify the effectiveness of the proposed method through numerical simulations.
{"title":"Optimal control of a hybrid system of photovoltaic and fuel cell in residential use","authors":"Juniku Matsuura, K. Kawahara, Zoka Yoshifumi","doi":"10.1109/UPEC.2014.6934629","DOIUrl":"https://doi.org/10.1109/UPEC.2014.6934629","url":null,"abstract":"In recent years, a photovoltaic solar energy system has widely spread on residential areas as an alternative energy of a fossil fuel. Since the output of photovoltaic (PV) cell sharply changes according to weather conditions, a certain power storage device is required to smooth the output and to meet electricity demand equivalent to a household load. Such devices are effective also a backup power at the time of a disaster like the Great East Japan Earthquake. A fuel cell (FC) is a promising candidate for long term energy system because hydrogen is supplied stably. We have so far proposed a hybrid system of PV and FC in residential use. The proposed system is consists of PV array, FC stack, electrolyzer (EL), hydrogen storage tank, and power conversion devices. This paper deals with a mixed integer programming problem for determining the amount of hydrogen flow and hydrogen remaining amount in the storage tank. We verify the effectiveness of the proposed method through numerical simulations.","PeriodicalId":414838,"journal":{"name":"2014 49th International Universities Power Engineering Conference (UPEC)","volume":"606 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117078194","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 : 2014-10-23DOI: 10.1109/UPEC.2014.6934641
A. Hassan, A. Firrincieli, C. Marmaras, L. Cipcigan, M. Pastorelli
Integration of renewable energy sources and Electric Vehicles (EVs) into a micro-grid was modeled. Time Series load flow for summer and winter load profiles was carried out. The voltage profiles over 24 hour period were evaluated for different Distributed Generators (DGs) and EV penetration. Uncontrolled and dual tariff EV charging were considered. The results indicate that voltage drops are less significant for the dual-tariff EV charging regime with increasing levels of DG penetration. Energy losses decrease in the case of dual tariff charging with maximum network loading (winter maximum load).
{"title":"Integration of electric vehicles in a microgrid with distributed generation","authors":"A. Hassan, A. Firrincieli, C. Marmaras, L. Cipcigan, M. Pastorelli","doi":"10.1109/UPEC.2014.6934641","DOIUrl":"https://doi.org/10.1109/UPEC.2014.6934641","url":null,"abstract":"Integration of renewable energy sources and Electric Vehicles (EVs) into a micro-grid was modeled. Time Series load flow for summer and winter load profiles was carried out. The voltage profiles over 24 hour period were evaluated for different Distributed Generators (DGs) and EV penetration. Uncontrolled and dual tariff EV charging were considered. The results indicate that voltage drops are less significant for the dual-tariff EV charging regime with increasing levels of DG penetration. Energy losses decrease in the case of dual tariff charging with maximum network loading (winter maximum load).","PeriodicalId":414838,"journal":{"name":"2014 49th International Universities Power Engineering Conference (UPEC)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129943487","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 : 2014-10-23DOI: 10.1109/UPEC.2014.6934742
N. Braiwish, F. Anayi, A. Fahmy, E. Eldukhri
Electric machines designs for traction application are concerned with paying particular attention to power density and efficiency. Therefore, this paper is focused on applying Bees algorithm (BA) for optimal design of Brushless Permanent Magnet Synchronous Motor (BLPMSM) for propulsion application. The analytical approach for the motor magnetic circuit is performed using the radial instantaneous magnetic field distribution in the airgap under specified loading condition; taking into account the magnetic core saturation and motor overall performance. The design aims to maximize the power density. Therefore, the optimisation objective function is formed to minimise motor weight and maximise efficiency. While the Bees Algorithm (BA) is applied to search for the optimum design parameters; the optimised design is then verified using Finite Element Method (FEM). Comparing with an existing machine, called here basic motor; the obtained results show that motor weight can be reduced by approximately 20%, while motor output power is kept constant. As the motor is designed for traction applications, the characteristics of the developed torque and speed were investigated under different gearing levels using magnetic gearing technique, the efficiency shows improvements in comparison to the basic motor.
{"title":"Design optimisation of Permanent Magnet Synchronous Motor for electric vehicles traction using the Bees Algorithm","authors":"N. Braiwish, F. Anayi, A. Fahmy, E. Eldukhri","doi":"10.1109/UPEC.2014.6934742","DOIUrl":"https://doi.org/10.1109/UPEC.2014.6934742","url":null,"abstract":"Electric machines designs for traction application are concerned with paying particular attention to power density and efficiency. Therefore, this paper is focused on applying Bees algorithm (BA) for optimal design of Brushless Permanent Magnet Synchronous Motor (BLPMSM) for propulsion application. The analytical approach for the motor magnetic circuit is performed using the radial instantaneous magnetic field distribution in the airgap under specified loading condition; taking into account the magnetic core saturation and motor overall performance. The design aims to maximize the power density. Therefore, the optimisation objective function is formed to minimise motor weight and maximise efficiency. While the Bees Algorithm (BA) is applied to search for the optimum design parameters; the optimised design is then verified using Finite Element Method (FEM). Comparing with an existing machine, called here basic motor; the obtained results show that motor weight can be reduced by approximately 20%, while motor output power is kept constant. As the motor is designed for traction applications, the characteristics of the developed torque and speed were investigated under different gearing levels using magnetic gearing technique, the efficiency shows improvements in comparison to the basic motor.","PeriodicalId":414838,"journal":{"name":"2014 49th International Universities Power Engineering Conference (UPEC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128766756","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 : 2014-10-23DOI: 10.1109/UPEC.2014.6934831
O. Pop
In the last years, induction heating systems have gained a big growing in the home appliances market. The following work proposes to design an induction cooking heating system. The power transfer process will be optimized by limiting or even eliminating switching losses using techniques such as zero current/voltage switching and by designing a parallel LC resonant circuit, which operates near at the resonant frequency. The paper will present a simulation and a design method for such type of converters, with an and without implementation of zero current switching algorithm.
{"title":"Analysis and simulation of quasi-resonant inverter for induction heating applications","authors":"O. Pop","doi":"10.1109/UPEC.2014.6934831","DOIUrl":"https://doi.org/10.1109/UPEC.2014.6934831","url":null,"abstract":"In the last years, induction heating systems have gained a big growing in the home appliances market. The following work proposes to design an induction cooking heating system. The power transfer process will be optimized by limiting or even eliminating switching losses using techniques such as zero current/voltage switching and by designing a parallel LC resonant circuit, which operates near at the resonant frequency. The paper will present a simulation and a design method for such type of converters, with an and without implementation of zero current switching algorithm.","PeriodicalId":414838,"journal":{"name":"2014 49th International Universities Power Engineering Conference (UPEC)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128370760","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 : 2014-10-23DOI: 10.1109/UPEC.2014.6934656
Kiyoto Kuraishi, T. Nanahara
Large-scale integration of wind power generation causes various concerns for its impacts on an electricity grid. One of the concerns is voltage stability of a power system because most wind power generators use an induction generator and the generator does not basically have a voltage supporting ability. Meanwhile, one of the authors has observed a phenomenon that limited variable speed machines kept a stable operation after a system disturbance with voltage level lower than that in a normal condition. However, operation of an induction generator in a low voltage solution is generally considered to be unstable. This paper analyzes voltage stability of wind power generations using the voltage-power curves (nose curves). Sensitivity studies are conducted for line impedance of fixed speed machine, for external resistance of a limited variable speed machine and for power factor of a variable speed machine. The results suggest the possibility for stable operation of a limited variable speed machine at a low voltage solution by controlling its external resistance.
{"title":"Fundamental study on voltage stability of induction generators for wind power generation — Voltage-power curves for various types of generators","authors":"Kiyoto Kuraishi, T. Nanahara","doi":"10.1109/UPEC.2014.6934656","DOIUrl":"https://doi.org/10.1109/UPEC.2014.6934656","url":null,"abstract":"Large-scale integration of wind power generation causes various concerns for its impacts on an electricity grid. One of the concerns is voltage stability of a power system because most wind power generators use an induction generator and the generator does not basically have a voltage supporting ability. Meanwhile, one of the authors has observed a phenomenon that limited variable speed machines kept a stable operation after a system disturbance with voltage level lower than that in a normal condition. However, operation of an induction generator in a low voltage solution is generally considered to be unstable. This paper analyzes voltage stability of wind power generations using the voltage-power curves (nose curves). Sensitivity studies are conducted for line impedance of fixed speed machine, for external resistance of a limited variable speed machine and for power factor of a variable speed machine. The results suggest the possibility for stable operation of a limited variable speed machine at a low voltage solution by controlling its external resistance.","PeriodicalId":414838,"journal":{"name":"2014 49th International Universities Power Engineering Conference (UPEC)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128573283","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 : 2014-10-23DOI: 10.1109/UPEC.2014.6934652
Xiayun Duan, M. Redfern
This paper examines the real value of the solar PV system for residential use. The analysis was based on a domestic property in Bath in the West of England. Two systems have been analysed, these consist of a solar PV system with and without energy storage. In each system, two PV capacity rating systems have been considered, 1.5 and 3.5 kWp. The analysis examined the value of the electricity generated including the contribution from the Feed in Tariff for the four quarters of the year. These together with the electricity consumption of a test household were then analysed and led to an assessment of the potential value of the electricity generated and the percentage electricity savings provided by the PV array.
{"title":"The value of PV electricity generation for domestic properties in the West of England","authors":"Xiayun Duan, M. Redfern","doi":"10.1109/UPEC.2014.6934652","DOIUrl":"https://doi.org/10.1109/UPEC.2014.6934652","url":null,"abstract":"This paper examines the real value of the solar PV system for residential use. The analysis was based on a domestic property in Bath in the West of England. Two systems have been analysed, these consist of a solar PV system with and without energy storage. In each system, two PV capacity rating systems have been considered, 1.5 and 3.5 kWp. The analysis examined the value of the electricity generated including the contribution from the Feed in Tariff for the four quarters of the year. These together with the electricity consumption of a test household were then analysed and led to an assessment of the potential value of the electricity generated and the percentage electricity savings provided by the PV array.","PeriodicalId":414838,"journal":{"name":"2014 49th International Universities Power Engineering Conference (UPEC)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123603903","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 : 2014-10-23DOI: 10.1109/UPEC.2014.6934710
Amanda E. Kahunzire, K. Awodele
As more Distributed Generation (DG) is connected to distribution networks; they are evolving from passive networks to active networks. Some of the new characteristics of active networks include bi-directional power flows, voltage profile issues, as well as unintentional islanding, to mention but a few. With these new characteristics, the present monitoring schemes characterized by slow and highly inaccurate measurements are no longer adequate. There is a need to develop a faster, more accurate real-time monitoring scheme. One way of achieving this is by installing Phasor Measurement Units (PMUs) on distribution networks. This paper investigates the impact that PMUs can have on distribution network monitoring. Specifically, it considers the role that appropriate PMU placement patterns have to play in improving Distribution System State Estimation (DSSE). Finally, it investigates the effect of improved system monitoring on the reliability of distribution systems.
{"title":"Improving distribution network state estimation by means of Phasor Measurement Units","authors":"Amanda E. Kahunzire, K. Awodele","doi":"10.1109/UPEC.2014.6934710","DOIUrl":"https://doi.org/10.1109/UPEC.2014.6934710","url":null,"abstract":"As more Distributed Generation (DG) is connected to distribution networks; they are evolving from passive networks to active networks. Some of the new characteristics of active networks include bi-directional power flows, voltage profile issues, as well as unintentional islanding, to mention but a few. With these new characteristics, the present monitoring schemes characterized by slow and highly inaccurate measurements are no longer adequate. There is a need to develop a faster, more accurate real-time monitoring scheme. One way of achieving this is by installing Phasor Measurement Units (PMUs) on distribution networks. This paper investigates the impact that PMUs can have on distribution network monitoring. Specifically, it considers the role that appropriate PMU placement patterns have to play in improving Distribution System State Estimation (DSSE). Finally, it investigates the effect of improved system monitoring on the reliability of distribution systems.","PeriodicalId":414838,"journal":{"name":"2014 49th International Universities Power Engineering Conference (UPEC)","volume":"486 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124047980","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 : 2014-10-23DOI: 10.1109/UPEC.2014.6934708
E. Plota, C. Rehtanz
Unmanaged charging of a commercial electric vehicle fleet at the grid connection point of an office building might cause higher grid usage costs and thereby high specific electricity costs due to an increase of power demand when charging with high rates. Through the year the charging load will vary due to dependence of consumption and range of the electric vehicle to the weather. Therefore the effect of unmanaged charging on the load curve is studied by means of simulation of charging with varying charging rates and differentiated energy consumption. Shifting load by controlled charging offers potential to relieve the electricity grid, but also to increase the business efficiency of the fleet operation. For the latter three mechanisms are considered in optimized charging. Limiting rising peak loads, increasing own consumption of PV generated energy, which feeds into the supply network of the office building as well as varying electricity tariffs are simulated, applying different scenarios.
{"title":"Impact of controlled charging of an electrical vehicle fleet on business efficiency","authors":"E. Plota, C. Rehtanz","doi":"10.1109/UPEC.2014.6934708","DOIUrl":"https://doi.org/10.1109/UPEC.2014.6934708","url":null,"abstract":"Unmanaged charging of a commercial electric vehicle fleet at the grid connection point of an office building might cause higher grid usage costs and thereby high specific electricity costs due to an increase of power demand when charging with high rates. Through the year the charging load will vary due to dependence of consumption and range of the electric vehicle to the weather. Therefore the effect of unmanaged charging on the load curve is studied by means of simulation of charging with varying charging rates and differentiated energy consumption. Shifting load by controlled charging offers potential to relieve the electricity grid, but also to increase the business efficiency of the fleet operation. For the latter three mechanisms are considered in optimized charging. Limiting rising peak loads, increasing own consumption of PV generated energy, which feeds into the supply network of the office building as well as varying electricity tariffs are simulated, applying different scenarios.","PeriodicalId":414838,"journal":{"name":"2014 49th International Universities Power Engineering Conference (UPEC)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128159037","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 : 2014-10-23DOI: 10.1109/UPEC.2014.6934766
H. Iswadi, D. Morrow, R. Best
The small signal stability of interconnected power systems is one of the important aspects that need to be investigated since the oscillations caused by this kind of instability have caused many incidents. With the increasing penetration of wind power in the power system, particularly doubly fed induction generator (DFIG), the impact on the power system small signal stability performance should be fully investigated. Because the DFIG wind turbine integration is through a fast action converter and associated control, it does not inherently participate in the electromechanical small signal oscillation. However, it influences the small signal stability by impacting active power flow paths in the network and replacing synchronous generators that have power system stabilizer (PSS). In this paper, the IEEE 39 bus test system has been used in the analysis. Furthermore, four study cases and several operation scenarios have been conducted and analysed. The selective eigenvalue Arnoldi/lanczos's method is used to obtain the system eigenvalue in the range of frequency from 0.2 Hz to 2 Hz which is related to electromechanical oscillations. Results show that the integration of DFIG wind turbines in a system during several study cases and operation scenarios give different influence on small signal stability performance.
{"title":"Small signal stability performance of power system during high penetration of wind generation","authors":"H. Iswadi, D. Morrow, R. Best","doi":"10.1109/UPEC.2014.6934766","DOIUrl":"https://doi.org/10.1109/UPEC.2014.6934766","url":null,"abstract":"The small signal stability of interconnected power systems is one of the important aspects that need to be investigated since the oscillations caused by this kind of instability have caused many incidents. With the increasing penetration of wind power in the power system, particularly doubly fed induction generator (DFIG), the impact on the power system small signal stability performance should be fully investigated. Because the DFIG wind turbine integration is through a fast action converter and associated control, it does not inherently participate in the electromechanical small signal oscillation. However, it influences the small signal stability by impacting active power flow paths in the network and replacing synchronous generators that have power system stabilizer (PSS). In this paper, the IEEE 39 bus test system has been used in the analysis. Furthermore, four study cases and several operation scenarios have been conducted and analysed. The selective eigenvalue Arnoldi/lanczos's method is used to obtain the system eigenvalue in the range of frequency from 0.2 Hz to 2 Hz which is related to electromechanical oscillations. Results show that the integration of DFIG wind turbines in a system during several study cases and operation scenarios give different influence on small signal stability performance.","PeriodicalId":414838,"journal":{"name":"2014 49th International Universities Power Engineering Conference (UPEC)","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125584962","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：