Pub Date : 2020-05-01DOI: 10.1109/ICEDME50972.2020.00026
Hao Chen, Xin Qiao, Feng Tian, Yunfei Sun
With the rapid improvement of power capacity and the continuous enlargement of the power grid, accidents caused by corrosion occurs frequently. Therefore, in order to ensure the reliability of power system, more and more attention has been paid to corrosion and protection of metallic components used in power grid equipment. In this paper, the macro and micro characteristics of galvanic corrosion, oxygen concentration corrosion, stress corrosion and intergranular corrosion for metallic components of electrical equipment were summarized, and the corresponding corrosion mechanism and corrosion behaviour were systematically investigated and analysed. Additionally, effective suggestions were put forward in order to improve the anti-corrosion performance of the metallic components and guarantee the safety and stability of power grid.
{"title":"Corrosion and Protection of Metallic Components in Power Grid Equipment","authors":"Hao Chen, Xin Qiao, Feng Tian, Yunfei Sun","doi":"10.1109/ICEDME50972.2020.00026","DOIUrl":"https://doi.org/10.1109/ICEDME50972.2020.00026","url":null,"abstract":"With the rapid improvement of power capacity and the continuous enlargement of the power grid, accidents caused by corrosion occurs frequently. Therefore, in order to ensure the reliability of power system, more and more attention has been paid to corrosion and protection of metallic components used in power grid equipment. In this paper, the macro and micro characteristics of galvanic corrosion, oxygen concentration corrosion, stress corrosion and intergranular corrosion for metallic components of electrical equipment were summarized, and the corresponding corrosion mechanism and corrosion behaviour were systematically investigated and analysed. Additionally, effective suggestions were put forward in order to improve the anti-corrosion performance of the metallic components and guarantee the safety and stability of power grid.","PeriodicalId":155375,"journal":{"name":"2020 3rd International Conference on Electron Device and Mechanical Engineering (ICEDME)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132945960","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 : 2020-05-01DOI: 10.1109/ICEDME50972.2020.00060
Liang Xue, Chang’an Hu, Shutong Luo, Jieji Li, Jiangang Li
Long term stress action is easy to cause stress crack of pressure vessel. In the process of producing corrosion stress crack, the early stage of crack growth is slow, and the evolution process reaches critical size, which will become a large crack in a very short time, with great harm. In this study, the influence of crack shape on eddy current detection signal is studied. The general finite element analysis software is used as the simulation calculation tool to study the influence of different crack shape on eddy current detection signal size. The control variable method is used to get the detection signal of different shape cracks under other fixed conditions. By comparing with the fatigue crack detection signal, we have mastered the influence of crack shape on detection signal.
{"title":"Study on the relationship between the shape of stress crack and its detection signal","authors":"Liang Xue, Chang’an Hu, Shutong Luo, Jieji Li, Jiangang Li","doi":"10.1109/ICEDME50972.2020.00060","DOIUrl":"https://doi.org/10.1109/ICEDME50972.2020.00060","url":null,"abstract":"Long term stress action is easy to cause stress crack of pressure vessel. In the process of producing corrosion stress crack, the early stage of crack growth is slow, and the evolution process reaches critical size, which will become a large crack in a very short time, with great harm. In this study, the influence of crack shape on eddy current detection signal is studied. The general finite element analysis software is used as the simulation calculation tool to study the influence of different crack shape on eddy current detection signal size. The control variable method is used to get the detection signal of different shape cracks under other fixed conditions. By comparing with the fatigue crack detection signal, we have mastered the influence of crack shape on detection signal.","PeriodicalId":155375,"journal":{"name":"2020 3rd International Conference on Electron Device and Mechanical Engineering (ICEDME)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134012922","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 : 2020-05-01DOI: 10.1109/ICEDME50972.2020.00048
Chen Shuo, Cao Lijun, Huang Shaoluo
Aiming at the difficulty of fault simulation in virtual maintenance training system, on the basis of studying the mechanism of fault generation, a fault model composed of maintenance object, fault source, fault phenomenon, fault propagation digraph and detection point is established by using object-oriented method, and the simulation of fault characteristic signal and fault phenomenon in virtual environment and the simulation operation flow are studied. The Virtools is used to realize the simulation. Now the modeling and Simulation of typical faults of equipment system is completed, and the real-time generation of fault phenomena and data is completed.
{"title":"Research on fault mechanism modeling method of virtual maintenance training equipment system","authors":"Chen Shuo, Cao Lijun, Huang Shaoluo","doi":"10.1109/ICEDME50972.2020.00048","DOIUrl":"https://doi.org/10.1109/ICEDME50972.2020.00048","url":null,"abstract":"Aiming at the difficulty of fault simulation in virtual maintenance training system, on the basis of studying the mechanism of fault generation, a fault model composed of maintenance object, fault source, fault phenomenon, fault propagation digraph and detection point is established by using object-oriented method, and the simulation of fault characteristic signal and fault phenomenon in virtual environment and the simulation operation flow are studied. The Virtools is used to realize the simulation. Now the modeling and Simulation of typical faults of equipment system is completed, and the real-time generation of fault phenomena and data is completed.","PeriodicalId":155375,"journal":{"name":"2020 3rd International Conference on Electron Device and Mechanical Engineering (ICEDME)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134412312","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 : 2020-05-01DOI: 10.1109/ICEDME50972.2020.00032
Sijin Wang, Chunsheng Guo, Boyang Liu, Lei Wei, Shiwei Zhang
The electrical method for measuring junction temperature inhomogeneity of IGBT modules has always been a scientific research problem in the field of microelectronics. This paper proposes a new type of electrical method for measuring junction temperature inhomogeneity, which is different from the conventional electrical methods using a single test condition. The collector currents measured in this paper are at high and low gate voltage, respectively. Based on the temperature calibration curve and the IGBT chips parallel model, the junction temperature inhomogeneity of the double-chip IGBT modules was analyzed successfully, and the junction temperature of the two chips were obtained respectively.
{"title":"Measuring Junction Temperature Inhomogeneity of Double-chip IGBT Modules by Electrical Method","authors":"Sijin Wang, Chunsheng Guo, Boyang Liu, Lei Wei, Shiwei Zhang","doi":"10.1109/ICEDME50972.2020.00032","DOIUrl":"https://doi.org/10.1109/ICEDME50972.2020.00032","url":null,"abstract":"The electrical method for measuring junction temperature inhomogeneity of IGBT modules has always been a scientific research problem in the field of microelectronics. This paper proposes a new type of electrical method for measuring junction temperature inhomogeneity, which is different from the conventional electrical methods using a single test condition. The collector currents measured in this paper are at high and low gate voltage, respectively. Based on the temperature calibration curve and the IGBT chips parallel model, the junction temperature inhomogeneity of the double-chip IGBT modules was analyzed successfully, and the junction temperature of the two chips were obtained respectively.","PeriodicalId":155375,"journal":{"name":"2020 3rd International Conference on Electron Device and Mechanical Engineering (ICEDME)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134512180","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 : 2020-05-01DOI: 10.1109/ICEDME50972.2020.00152
Jing Sun
According to disadvantages of low convergence rate, big steady-state and local convergence error of traditional equalization constant modulus algorithm(CMA), combined with the orthogonal wavelet transform and the chicken swarm optimization algorithm(CSO), an orthogonal wavelet transform blind equalization algorithm based on chicken swarm optimization algorithm (CSO-WT-CMA) is proposed. Based on the CMA, the proposed algorithm improved the convergence rate by using the orthogonal wavelet transform to normalize the transmission signal (WT-CMA). Meanwhile, in order to avoid premature convergence, local optimization and can’t achieve global optimization, inertia weight factor is introduced into the location update formula of hens and chicks, improving the global search and local search ability. Computer simulations in underwater acoustic channels indicate that the proposed algorithm outperforms the WT-CMA in mean square error and convergence rate.
{"title":"Orthogonal Wavelet Transform Blind Equalization Algorithm based on Chicken Swarm Optimization Algorithm","authors":"Jing Sun","doi":"10.1109/ICEDME50972.2020.00152","DOIUrl":"https://doi.org/10.1109/ICEDME50972.2020.00152","url":null,"abstract":"According to disadvantages of low convergence rate, big steady-state and local convergence error of traditional equalization constant modulus algorithm(CMA), combined with the orthogonal wavelet transform and the chicken swarm optimization algorithm(CSO), an orthogonal wavelet transform blind equalization algorithm based on chicken swarm optimization algorithm (CSO-WT-CMA) is proposed. Based on the CMA, the proposed algorithm improved the convergence rate by using the orthogonal wavelet transform to normalize the transmission signal (WT-CMA). Meanwhile, in order to avoid premature convergence, local optimization and can’t achieve global optimization, inertia weight factor is introduced into the location update formula of hens and chicks, improving the global search and local search ability. Computer simulations in underwater acoustic channels indicate that the proposed algorithm outperforms the WT-CMA in mean square error and convergence rate.","PeriodicalId":155375,"journal":{"name":"2020 3rd International Conference on Electron Device and Mechanical Engineering (ICEDME)","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115616001","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 : 2020-05-01DOI: 10.1109/ICEDME50972.2020.00045
Yu Yang
The ultrafine crystallization of 20 steel can make it have higher tensile strength, corrosion resistance and thermal stability. Therefore, it is widely used in the fields of medical instruments, aerospace and passenger vehicle manufacturing. However, the development of spinning technology has been limited in the theoretical research stage. In this paper, the tube 20 steel is taken as the research object, and the ultra-fine grain forming process based on "three pass strong spinning - heat treatment - two pass common spinning - heat treatment" is proposed. On the basis of spinning process test, the ultimate thinning rate of this method is explored, and the evolution rule of its surface microstructure is analyzed by metallographic microscope. The results show that the multi pass spinning with small and medium thinning makes the grain structure elongate along the axial and tangential directions, and then refine. The uniformity of the axial fiber structure was improved. The research results are of great scientific significance to reduce the consumption of high-performance metals, improve the utilization rate and properties of materials, and promote the development of preparation technology of ultrafine grained metals.
{"title":"Research on the Preparation and Mechanism of Ultrafine Crystallization of 20 Steel by Strong Spinning","authors":"Yu Yang","doi":"10.1109/ICEDME50972.2020.00045","DOIUrl":"https://doi.org/10.1109/ICEDME50972.2020.00045","url":null,"abstract":"The ultrafine crystallization of 20 steel can make it have higher tensile strength, corrosion resistance and thermal stability. Therefore, it is widely used in the fields of medical instruments, aerospace and passenger vehicle manufacturing. However, the development of spinning technology has been limited in the theoretical research stage. In this paper, the tube 20 steel is taken as the research object, and the ultra-fine grain forming process based on \"three pass strong spinning - heat treatment - two pass common spinning - heat treatment\" is proposed. On the basis of spinning process test, the ultimate thinning rate of this method is explored, and the evolution rule of its surface microstructure is analyzed by metallographic microscope. The results show that the multi pass spinning with small and medium thinning makes the grain structure elongate along the axial and tangential directions, and then refine. The uniformity of the axial fiber structure was improved. The research results are of great scientific significance to reduce the consumption of high-performance metals, improve the utilization rate and properties of materials, and promote the development of preparation technology of ultrafine grained metals.","PeriodicalId":155375,"journal":{"name":"2020 3rd International Conference on Electron Device and Mechanical Engineering (ICEDME)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114774270","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 : 2020-05-01DOI: 10.1109/ICEDME50972.2020.00043
Liu Yan-shu, Wang Yu
There are many deep hole processing methods for TC4 titanium alloy, but it is a blank to drill with a mahine-clamped deep hole drill, so we have carried out some experi--mental studies. Using different spindle speed and feed in the test process of chip morphology and chip removal condition respectively and drill bit, the abrasion of guide block is analyzed using single factor method is suitable for the machine clamp type TC4 titanium alloy drilling deep hole drill in the best condition, get the best speed, the best feeding, for deep hole drill machine clamp type provides effective of TC4 titanium alloy drilling processing parameters.
{"title":"Experimental Study of TC4 Titanium Alloy Deep Hole Drilling Based on Machine-Clamped Deep Hole Drill","authors":"Liu Yan-shu, Wang Yu","doi":"10.1109/ICEDME50972.2020.00043","DOIUrl":"https://doi.org/10.1109/ICEDME50972.2020.00043","url":null,"abstract":"There are many deep hole processing methods for TC4 titanium alloy, but it is a blank to drill with a mahine-clamped deep hole drill, so we have carried out some experi--mental studies. Using different spindle speed and feed in the test process of chip morphology and chip removal condition respectively and drill bit, the abrasion of guide block is analyzed using single factor method is suitable for the machine clamp type TC4 titanium alloy drilling deep hole drill in the best condition, get the best speed, the best feeding, for deep hole drill machine clamp type provides effective of TC4 titanium alloy drilling processing parameters.","PeriodicalId":155375,"journal":{"name":"2020 3rd International Conference on Electron Device and Mechanical Engineering (ICEDME)","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122974580","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}
Vertical-cavity surface-emitting lasers (VCSELs) with 894.6nm as the ideal light source for cesium (Cs) atomic clock is analyzed. The VCSEL with central wavelength of 894.6nm is designed and fabricated for Cs atomic clock using the control mode of two-dimensional triangular-hole structure oxidation type VCSEL. The output power is 0.86mw, with the single mode suppression ratio (SMSR) of more than 20dB and the threshold current of 1mA. The observation of laser spectrum and far-field pattern shows that the single-mode VCSEL can be used in atomic clock successfully.
{"title":"894.6nm VCSEL for Cs-Based Atomic Clocks with triangular holey structure","authors":"W. Pang, Guanzhong Pan, Qiuhua Wang, Liangchen Hu, Zhuangzhuang Zhao, Yiyang Xie","doi":"10.1109/ICEDME50972.2020.00136","DOIUrl":"https://doi.org/10.1109/ICEDME50972.2020.00136","url":null,"abstract":"Vertical-cavity surface-emitting lasers (VCSELs) with 894.6nm as the ideal light source for cesium (Cs) atomic clock is analyzed. The VCSEL with central wavelength of 894.6nm is designed and fabricated for Cs atomic clock using the control mode of two-dimensional triangular-hole structure oxidation type VCSEL. The output power is 0.86mw, with the single mode suppression ratio (SMSR) of more than 20dB and the threshold current of 1mA. The observation of laser spectrum and far-field pattern shows that the single-mode VCSEL can be used in atomic clock successfully.","PeriodicalId":155375,"journal":{"name":"2020 3rd International Conference on Electron Device and Mechanical Engineering (ICEDME)","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128928992","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 : 2020-05-01DOI: 10.1109/ICEDME50972.2020.00050
Hongguang Li
During laser welding of titanium alloy, it is easy to absorb nitrogen, oxygen and hydrogen in the surrounding air, and react with them to form a gap solid solution, which hinders the movement of dislocations between grain boundaries and significantly improves the hardness of the weld, but its plasticity will deteriorate, resulting in the embrittlement of the whole welded joint. Because of the low thermal conductivity of titanium alloy, the weld pool continuously transfers the heat to the heat affected zone in the way of heat conduction, which keeps the heat affected zone at a high temperature all the time. In this way, the volume of hydride precipitated rapidly expands, resulting in a large local stress. When the local stress exceeds the yield limit of the material, cracks will occur. The quality of welding joint determines the reliability and economy of welding structure to a great extent. The defects of welded joints often destroy the performance of components, and in some cases, accidents will occur. Therefore, the control of weld defects is particularly important.
{"title":"Analysis and control of laser weld crack","authors":"Hongguang Li","doi":"10.1109/ICEDME50972.2020.00050","DOIUrl":"https://doi.org/10.1109/ICEDME50972.2020.00050","url":null,"abstract":"During laser welding of titanium alloy, it is easy to absorb nitrogen, oxygen and hydrogen in the surrounding air, and react with them to form a gap solid solution, which hinders the movement of dislocations between grain boundaries and significantly improves the hardness of the weld, but its plasticity will deteriorate, resulting in the embrittlement of the whole welded joint. Because of the low thermal conductivity of titanium alloy, the weld pool continuously transfers the heat to the heat affected zone in the way of heat conduction, which keeps the heat affected zone at a high temperature all the time. In this way, the volume of hydride precipitated rapidly expands, resulting in a large local stress. When the local stress exceeds the yield limit of the material, cracks will occur. The quality of welding joint determines the reliability and economy of welding structure to a great extent. The defects of welded joints often destroy the performance of components, and in some cases, accidents will occur. Therefore, the control of weld defects is particularly important.","PeriodicalId":155375,"journal":{"name":"2020 3rd International Conference on Electron Device and Mechanical Engineering (ICEDME)","volume":"160 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116438509","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 : 2020-05-01DOI: 10.1109/ICEDME50972.2020.00018
Boyang Liu, Chunsheng Guo, Sijin Wang, Hang Wei, Lei Wei
This paper proposes a novel method for online junction temperature measurement of silicon carbide metaloxide-semiconductor field-effect transistors (SiC MOSFETs). The measurement method is using the miller plateau voltage (VGS) and source leakage current (IDS) at transient inrush currents during turn-on process that based on the temperaturesensitive electrical parameters measurement method (TSEP). The comparison of infrared temperature measurement results shows that this method can provide more accurate junction temperature results and also can be used for transient junction temperature measurement in SiC MOSFET devices. It solves the problem that the traditional temperature-sensitive electrical parameter measurement method is difficult to measure the transient temperature rise. Finally, the results show that the use of VGS and IDS can provide more accurate junction temperature results which can be used for transient junction temperatures in SiC MOSEFT devices.
{"title":"Online Junction Temperature Measurement Method of SiC MOS Devices Using Multiple Electrical Parameters at Transient Surge Current","authors":"Boyang Liu, Chunsheng Guo, Sijin Wang, Hang Wei, Lei Wei","doi":"10.1109/ICEDME50972.2020.00018","DOIUrl":"https://doi.org/10.1109/ICEDME50972.2020.00018","url":null,"abstract":"This paper proposes a novel method for online junction temperature measurement of silicon carbide metaloxide-semiconductor field-effect transistors (SiC MOSFETs). The measurement method is using the miller plateau voltage (VGS) and source leakage current (IDS) at transient inrush currents during turn-on process that based on the temperaturesensitive electrical parameters measurement method (TSEP). The comparison of infrared temperature measurement results shows that this method can provide more accurate junction temperature results and also can be used for transient junction temperature measurement in SiC MOSFET devices. It solves the problem that the traditional temperature-sensitive electrical parameter measurement method is difficult to measure the transient temperature rise. Finally, the results show that the use of VGS and IDS can provide more accurate junction temperature results which can be used for transient junction temperatures in SiC MOSEFT devices.","PeriodicalId":155375,"journal":{"name":"2020 3rd International Conference on Electron Device and Mechanical Engineering (ICEDME)","volume":"76 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116289828","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：