Pub Date : 2018-06-01DOI: 10.1109/SPEEDAM.2018.8445414
A. K. Jha, Ziwei Li, Adolfo G. Garcia, Pranshu Upadhayay, P. Rasmussen, Afef Kedous-Lcbouc, L. Garbuio
With increasing demand of electric vehicles it is very important to recycle critical rare earth materials used in the permanent magnet motors such as Neodymium (Nd), Dysprosium (Dy) and Cobalt (Co) etc. To achieve easy recycling, focus of the motor design shall shift to design for recycling. The article presents a methodology (WIRE) to evaluate and benchmark the motor in terms of their recyclability. The method can be used to compare different motors. The method was used for evaluation of a commercial permanent magnet based HUB motor and the results are presented. A comparison between recyclability index of four different motors topology is also presented.
{"title":"Weighted Index of Recycling and Energy (WIRE) Cost for Motors in Electric Vehicles","authors":"A. K. Jha, Ziwei Li, Adolfo G. Garcia, Pranshu Upadhayay, P. Rasmussen, Afef Kedous-Lcbouc, L. Garbuio","doi":"10.1109/SPEEDAM.2018.8445414","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2018.8445414","url":null,"abstract":"With increasing demand of electric vehicles it is very important to recycle critical rare earth materials used in the permanent magnet motors such as Neodymium (Nd), Dysprosium (Dy) and Cobalt (Co) etc. To achieve easy recycling, focus of the motor design shall shift to design for recycling. The article presents a methodology (WIRE) to evaluate and benchmark the motor in terms of their recyclability. The method can be used to compare different motors. The method was used for evaluation of a commercial permanent magnet based HUB motor and the results are presented. A comparison between recyclability index of four different motors topology is also presented.","PeriodicalId":117883,"journal":{"name":"2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115934807","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 : 2018-06-01DOI: 10.1109/SPEEDAM.2018.8445329
Léopold Sepulchre, M. Fadel, Maria Ptetrzak-David
Synchronous motors with Interior Permanent Magnets (IPMSM) are particularly effective for operation at high speed due to their high power density. However the speeds generate large electromagnetic forces and it is necessary to set up a flux-weakening. Classical control algorithms do flux-weakening by injecting a negative $mathbf{I}_{mathrm{d}}$ current in respect of current norm. The value of this current is usually defined on the LUTs (Look Up Tables) depending on the speed and the torque required reflecting open-loop operation. This article presents continuous control law in closed loop ensuring the operation from the speed zero up to the maximum speed. The generation of the current reference $mathbf{I}_{mathrm{d}}$ is based on strategy to Minimum Current per Torque (MinCPT) followed a Maximum Torque per Volt (MTPV) strategy. The goal is to maximize the speed for a given power. The effectiveness of this unified algorithm is tested on an experimental platform.
{"title":"MTPV for Continuous Flux-Weakening Strategy Control Law for IPMSM","authors":"Léopold Sepulchre, M. Fadel, Maria Ptetrzak-David","doi":"10.1109/SPEEDAM.2018.8445329","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2018.8445329","url":null,"abstract":"Synchronous motors with Interior Permanent Magnets (IPMSM) are particularly effective for operation at high speed due to their high power density. However the speeds generate large electromagnetic forces and it is necessary to set up a flux-weakening. Classical control algorithms do flux-weakening by injecting a negative $mathbf{I}_{mathrm{d}}$ current in respect of current norm. The value of this current is usually defined on the LUTs (Look Up Tables) depending on the speed and the torque required reflecting open-loop operation. This article presents continuous control law in closed loop ensuring the operation from the speed zero up to the maximum speed. The generation of the current reference $mathbf{I}_{mathrm{d}}$ is based on strategy to Minimum Current per Torque (MinCPT) followed a Maximum Torque per Volt (MTPV) strategy. The goal is to maximize the speed for a given power. The effectiveness of this unified algorithm is tested on an experimental platform.","PeriodicalId":117883,"journal":{"name":"2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124372083","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 : 2018-06-01DOI: 10.1109/SPEEDAM.2018.8445365
P. Guerriero, I. Matacena, S. Daliento
This paper proposes a method to recover energy losses occurring in partially shaded solar fields when the MPPT algorithm converge in a local maximum power point in place of the global maximum power point. The method is based on the observation that the distortion of the power voltage curve, and the appearance of multiple maxima, originates from the turning off of bypass diodes when, at increasing voltages, the current delivered by sunny modules becomes comparable with that delivered by shaded ones. Forced bypass of shaded modules smoothes the power voltage curve and allows the MPPT to reach the global maximum power point.
{"title":"Reconfiguration of solar fields by means of forced activation of bypass diodes","authors":"P. Guerriero, I. Matacena, S. Daliento","doi":"10.1109/SPEEDAM.2018.8445365","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2018.8445365","url":null,"abstract":"This paper proposes a method to recover energy losses occurring in partially shaded solar fields when the MPPT algorithm converge in a local maximum power point in place of the global maximum power point. The method is based on the observation that the distortion of the power voltage curve, and the appearance of multiple maxima, originates from the turning off of bypass diodes when, at increasing voltages, the current delivered by sunny modules becomes comparable with that delivered by shaded ones. Forced bypass of shaded modules smoothes the power voltage curve and allows the MPPT to reach the global maximum power point.","PeriodicalId":117883,"journal":{"name":"2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114745465","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 : 2018-06-01DOI: 10.1109/SPEEDAM.2018.8445340
M. Dudzik, A. Jagiełło, S. Drapik, J. Prusak
The paper constitutes a continuation of research on load variability of rectifier units. The research are made for the selected tram substation. The performed analysis uses the actual measurements. This time the analysis focuses on relation between the maximum loads and 60 minutes overloads currents. The second part of the paper shows the effectiveness of use of the feedforward type artificial neural network. The effectiveness of the analyze was calculated for 250 times, for 50 cases. The results shown in the paper were obtained for optimal structure of the artificial neural network. The results presented in this publication prove to be the best results among the results known by the authors of the work.
{"title":"The selected real tramway substation overload analysis using the optimal structure of an artificial neural network","authors":"M. Dudzik, A. Jagiełło, S. Drapik, J. Prusak","doi":"10.1109/SPEEDAM.2018.8445340","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2018.8445340","url":null,"abstract":"The paper constitutes a continuation of research on load variability of rectifier units. The research are made for the selected tram substation. The performed analysis uses the actual measurements. This time the analysis focuses on relation between the maximum loads and 60 minutes overloads currents. The second part of the paper shows the effectiveness of use of the feedforward type artificial neural network. The effectiveness of the analyze was calculated for 250 times, for 50 cases. The results shown in the paper were obtained for optimal structure of the artificial neural network. The results presented in this publication prove to be the best results among the results known by the authors of the work.","PeriodicalId":117883,"journal":{"name":"2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117006394","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 : 2018-06-01DOI: 10.1109/SPEEDAM.2018.8445370
Pieter Nguyen Phuc, K. Stockman, G. Crevecoeur
Thermal modelling of induction machines is becoming increasingly important with the demand for machines with ever increasing efficiency as well as compact design. The lumped parameter thermal model is a flexible and computationally cheap method for the temperature analysis inside an induction machine. However, there are a number of thermal parameter values which are difficult to determine analytically. This includes the air gap convection coefficient, the equivalent radial conductivity of the stator winding and the width of the equivalent air gap between the frame and the stator lamination. In this work, the identification of the thermal model values follows the inverse methodology: assign values to the thermal parameters by aligning temperature measurements at a specific location in the motor with the lumped-parameter model response. Simulation results show that the accuracy of the proposed thermal parameter identification scheme depends on the location of the thermal measurement and more specifically on the sensitivity of the temperature profile with respect to the unknown parameters.
{"title":"Inverse Methodology for the Parameter Identification of a Lumped Parameter Thermal Network for an Induction Machine","authors":"Pieter Nguyen Phuc, K. Stockman, G. Crevecoeur","doi":"10.1109/SPEEDAM.2018.8445370","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2018.8445370","url":null,"abstract":"Thermal modelling of induction machines is becoming increasingly important with the demand for machines with ever increasing efficiency as well as compact design. The lumped parameter thermal model is a flexible and computationally cheap method for the temperature analysis inside an induction machine. However, there are a number of thermal parameter values which are difficult to determine analytically. This includes the air gap convection coefficient, the equivalent radial conductivity of the stator winding and the width of the equivalent air gap between the frame and the stator lamination. In this work, the identification of the thermal model values follows the inverse methodology: assign values to the thermal parameters by aligning temperature measurements at a specific location in the motor with the lumped-parameter model response. Simulation results show that the accuracy of the proposed thermal parameter identification scheme depends on the location of the thermal measurement and more specifically on the sensitivity of the temperature profile with respect to the unknown parameters.","PeriodicalId":117883,"journal":{"name":"2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116396109","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 : 2018-06-01DOI: 10.1109/SPEEDAM.2018.8445295
C. Concari, G. Pietrini, Alessandro Soldati, C. Tassoni, A. Toscani, G. Franceschini
This paper extends the authors' deep investigation of the electric rotor fault signatures of induction machines to machines of different size operating in various conditions. Authors researches have already shown the limits of the usual diagnostic procedures based on the sum of both left and right current sidebands. A proper faulty machine model leading to a more robust diagnosis has been proposed and the effect of machine size and load conditions on current space vector sidebands, flux, torque and speed spectral components is shown. These physical quantities, in case of small faults, can be described by their representative phasors in a synchronous reference frame. The analytical links among the phasors are validated by simulations and experiments. The prominent role of mechanical inertia in the diagnostic process is highlighted, assessing the range of validity of the usual diagnostic index versus machine size and load, eventually an alternative procedure is here proposed.
{"title":"Induction Machines with Rotor Faults: Analysis of the Physical Quantities for Different Operating Conditions and Machine Sizes for Improved Diagnostics","authors":"C. Concari, G. Pietrini, Alessandro Soldati, C. Tassoni, A. Toscani, G. Franceschini","doi":"10.1109/SPEEDAM.2018.8445295","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2018.8445295","url":null,"abstract":"This paper extends the authors' deep investigation of the electric rotor fault signatures of induction machines to machines of different size operating in various conditions. Authors researches have already shown the limits of the usual diagnostic procedures based on the sum of both left and right current sidebands. A proper faulty machine model leading to a more robust diagnosis has been proposed and the effect of machine size and load conditions on current space vector sidebands, flux, torque and speed spectral components is shown. These physical quantities, in case of small faults, can be described by their representative phasors in a synchronous reference frame. The analytical links among the phasors are validated by simulations and experiments. The prominent role of mechanical inertia in the diagnostic process is highlighted, assessing the range of validity of the usual diagnostic index versus machine size and load, eventually an alternative procedure is here proposed.","PeriodicalId":117883,"journal":{"name":"2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122059996","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 : 2018-06-01DOI: 10.1109/SPEEDAM.2018.8445369
A. Dannier, P. Guerriero, M. Coppola, G. Brando
The paper deals with a high performance fast charger system for Zero Electric Vehicles (ZEVs). The proposed converter, which is built upon two interleaved three-leg two-level Voltage Source Converters (VSC), allows for a substantial increase of the total output power, thus leading to a high reliable topology. Furthermore, this approach allows a strong reduction of the output voltage ripple while exhibiting excellent dependability characteristics. The performance of the proposed DC/DC converter is validated by an extended numerical analysis, which confirms the effectiveness of both the control strategy and the system topology.
{"title":"Interleaved converter for fast charge of battery system","authors":"A. Dannier, P. Guerriero, M. Coppola, G. Brando","doi":"10.1109/SPEEDAM.2018.8445369","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2018.8445369","url":null,"abstract":"The paper deals with a high performance fast charger system for Zero Electric Vehicles (ZEVs). The proposed converter, which is built upon two interleaved three-leg two-level Voltage Source Converters (VSC), allows for a substantial increase of the total output power, thus leading to a high reliable topology. Furthermore, this approach allows a strong reduction of the output voltage ripple while exhibiting excellent dependability characteristics. The performance of the proposed DC/DC converter is validated by an extended numerical analysis, which confirms the effectiveness of both the control strategy and the system topology.","PeriodicalId":117883,"journal":{"name":"2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124651245","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 : 2018-06-01DOI: 10.1109/SPEEDAM.2018.8445371
M. M. Bijaieh, W. Weaver, R. Robinett
The distributed nature of micro-sources with intermittent behavior requires development of appropriate microgrid integration schemes. In a system comprising of solely renewable sources that have no inertia, the operation at a fixed frequency with effective power sharing capability is a viable solution. This paper presents the effects of dc droop settings on the energy storage systems of three-phase microgrids that utilize a dq droop control for power sharing at a fixed frequency. The microgrid control is modeled according to the Hamiltonian Surface Shaping and Power Flow Control (HSSPFC) scheme. The energy storage control law is developed so that the required storage is in a minimal form however, the choice of grid-side local droop control settings may impose significant burden on source-side dc energy storage systems. Two simulation examples of energy storage requirements versus the dq droop settings are presented in this paper.
{"title":"Effects of DQ Droop Settings on Energy Storage Systems of Inverter-Based Microgrids","authors":"M. M. Bijaieh, W. Weaver, R. Robinett","doi":"10.1109/SPEEDAM.2018.8445371","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2018.8445371","url":null,"abstract":"The distributed nature of micro-sources with intermittent behavior requires development of appropriate microgrid integration schemes. In a system comprising of solely renewable sources that have no inertia, the operation at a fixed frequency with effective power sharing capability is a viable solution. This paper presents the effects of dc droop settings on the energy storage systems of three-phase microgrids that utilize a dq droop control for power sharing at a fixed frequency. The microgrid control is modeled according to the Hamiltonian Surface Shaping and Power Flow Control (HSSPFC) scheme. The energy storage control law is developed so that the required storage is in a minimal form however, the choice of grid-side local droop control settings may impose significant burden on source-side dc energy storage systems. Two simulation examples of energy storage requirements versus the dq droop settings are presented in this paper.","PeriodicalId":117883,"journal":{"name":"2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)","volume":"61 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129532324","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 : 2018-06-01DOI: 10.1109/SPEEDAM.2018.8445367
A. Anuchin, D. Shpak, M. Gulyaeva, D. Aliamkin, A. Zharkov, Y. Vagapov
This paper discusses the approach for the witching loss minimisation in a 3-level inverter. It utilises a model predictive method which is used for evaluation of both the switching loss and voltage unbalance. The method is based on the cost functions implemented to provide simultaneous minimisation of loss and DC link voltage balance control. The simulation results shown that the total loss is reduced in 15% compared to a standard PWM strategy for a 3-level inverter operating at PWM frequency of 16 kHz.
{"title":"A PWM Strategy for the Minimisation of Losses in a 3-level T-type Voltage Source Inverter","authors":"A. Anuchin, D. Shpak, M. Gulyaeva, D. Aliamkin, A. Zharkov, Y. Vagapov","doi":"10.1109/SPEEDAM.2018.8445367","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2018.8445367","url":null,"abstract":"This paper discusses the approach for the witching loss minimisation in a 3-level inverter. It utilises a model predictive method which is used for evaluation of both the switching loss and voltage unbalance. The method is based on the cost functions implemented to provide simultaneous minimisation of loss and DC link voltage balance control. The simulation results shown that the total loss is reduced in 15% compared to a standard PWM strategy for a 3-level inverter operating at PWM frequency of 16 kHz.","PeriodicalId":117883,"journal":{"name":"2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128233897","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 : 2018-06-01DOI: 10.1109/SPEEDAM.2018.8445335
A. Andreotti, F. Mottola, A. Pierno, D. Proto
Power quality issues are fundamental in modern power systems. With reference to the lightning phenomenon, induced voltage is one of the problems that is drawing greater and greater attention for distribution lines. An adequate strategy of protection is then needed in order to prevent damages and outages. In this scenario, an accurate analysis of the induced-voltages effects is then essential, and randomness of the phenomenon has also to be considered. In this work, a probabilistic procedure is applied: particularly, an exact analytical solution is used within a Monte Carlo procedure. The analytical solution to evaluate the induced voltage peak value is applied with reference to measured data on first stroke current values. Further, an analysis has been carried out in order to look for the parametric distributions that best match the obtained distributions.
{"title":"Statistical features of lightning-induced voltages","authors":"A. Andreotti, F. Mottola, A. Pierno, D. Proto","doi":"10.1109/SPEEDAM.2018.8445335","DOIUrl":"https://doi.org/10.1109/SPEEDAM.2018.8445335","url":null,"abstract":"Power quality issues are fundamental in modern power systems. With reference to the lightning phenomenon, induced voltage is one of the problems that is drawing greater and greater attention for distribution lines. An adequate strategy of protection is then needed in order to prevent damages and outages. In this scenario, an accurate analysis of the induced-voltages effects is then essential, and randomness of the phenomenon has also to be considered. In this work, a probabilistic procedure is applied: particularly, an exact analytical solution is used within a Monte Carlo procedure. The analytical solution to evaluate the induced voltage peak value is applied with reference to measured data on first stroke current values. Further, an analysis has been carried out in order to look for the parametric distributions that best match the obtained distributions.","PeriodicalId":117883,"journal":{"name":"2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129354499","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：