Electric Power Systems Research最新文献_第7页

A SEPIC-Ćuk derived hybrid converter with single-input inductor and dual DC/AC outputs for microgrid applications 一种SEPIC-Ćuk衍生的混合转换器，具有单输入电感和双直流/交流输出，用于微电网应用

IF 4.2 3区工程技术

Electric Power Systems Research Pub Date : 2026-06-01 Epub Date: 2026-02-12 DOI: 10.1016/j.epsr.2026.112844

Md. Sohel Rana , Md. Anwarul Abedin , Waqas Hassan , Md. Alamgir Hossain , Alamgir Hossain

{"title":"A SEPIC-Ćuk derived hybrid converter with single-input inductor and dual DC/AC outputs for microgrid applications","authors":"Md. Sohel Rana , Md. Anwarul Abedin , Waqas Hassan , Md. Alamgir Hossain , Alamgir Hossain","doi":"10.1016/j.epsr.2026.112844","DOIUrl":"10.1016/j.epsr.2026.112844","url":null,"abstract":"<div><div>As load profiles continue to shift toward a hybrid mix of AC and DC, microgrids increasingly require cost-effective converters capable of powering both AC and DC loads simultaneously. However, existing converter topologies often exhibit limitations including inadequate voltage gain, high switching stress, complex control schemes, and reliability challenges. To address these challenges, this paper proposes a novel SEPIC-Ćuk Derived Hybrid Converter (SCDHC), integrating SEPIC and Ćuk converters utilizing a single, shared input inductor and replacing the conventional control switch with a single-phase voltage-source inverter (VSI). This design achieves double the DC voltage gain compared to conventional SEPIC, Ćuk, or SEPIC/Ćuk-based hybrid converters, while exhibiting lower switching stress, and inherently provides shoot-through protection for the AC output, significantly enhancing reliability while reducing the required number of control switches. A modified unipolar sinusoidal pulse width modulation (SPWM) strategy is adopted to regulate power flow, while a memory-efficient switching scheme, implemented by Verilog HDL on an FPGA, ensures precise gate pulse generation. The converter’s steady-state behavior, cross-regulation performance, and dynamic response under step load changes are thoroughly analyzed. Experimental validation using an 80 W laboratory prototype substantiates the SCDHC’s ability to maintain stable and regulated DC and AC outputs under varying load conditions. Comparative evaluations demonstrate the proposed converter’s superiority over existing topologies in terms of voltage gain, efficiency, component count, reliability, switching stress, and control complexity, highlighting its suitability for residential microgrid applications requiring simultaneous DC and AC power delivery from a single DC source.</div></div>","PeriodicalId":50547,"journal":{"name":"Electric Power Systems Research","volume":"255 ","pages":"Article 112844"},"PeriodicalIF":4.2,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Wave propagation analysis of HTLS conductors with equivalent electrical performance to conventional conductors 电性能与传统导体相当的HTLS导体的波传播分析

IF 4.2 3区工程技术

Electric Power Systems Research Pub Date : 2026-06-01 Epub Date: 2026-01-14 DOI: 10.1016/j.epsr.2026.112737

Jesus E. Guevara Asorza , Theofilos A. Papadopoulos , Ricardo A. De Araujo , José Pissolato Filho

{"title":"Wave propagation analysis of HTLS conductors with equivalent electrical performance to conventional conductors","authors":"Jesus E. Guevara Asorza , Theofilos A. Papadopoulos , Ricardo A. De Araujo , José Pissolato Filho","doi":"10.1016/j.epsr.2026.112737","DOIUrl":"10.1016/j.epsr.2026.112737","url":null,"abstract":"<div><div>This study examines the effect of replacing conventional conductors with high-temperature, low-sag (HTLS) conductors in overhead transmission lines, with a focus on electrical performance. The research analyzes both steady-state and transient behavior, focusing on modifications in propagation modes and the response to electrical excitations. The steady-state analysis reveals that the best HTLS conductors selected that meet ampacity requirements do not satisfy the critical electric field gradient limit. To address this limitation, two HTLS conductors were chosen, and the number of conductors per phase was varied. In the propagation modes, HTLS conductors show a lower phase velocity at low frequencies but exhibit similar behavior to conventional conductors at high frequencies. Additionally, subtle variations in attenuation constants were observed. In the transient analysis, the response to a step voltage excitation demonstrates that HTLS conductors attenuate overvoltages more quickly than conventional ones. Soil resistivity is found to be a determining factor: higher values lead to lower overvoltage amplitudes and faster attenuation, while lower values result in higher amplitudes and delayed wave dissipation. This relationship between soil resistivity and transient behavior emphasizes the importance of this parameter in ensuring model accuracy and system safety. The results suggest that the selected HTLS conductors did not show significant differences in transient response, highlighting the need for further studies to assess their performance in switching operations and atmospheric discharges, with the goal of improving the reliability of transmission systems.</div></div>","PeriodicalId":50547,"journal":{"name":"Electric Power Systems Research","volume":"255 ","pages":"Article 112737"},"PeriodicalIF":4.2,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145980426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Study on surface hydrophobicity of silicone rubber insulator with grating structure based on nanosecond pulse laser processing 基于纳秒脉冲激光加工的光栅结构硅橡胶绝缘子表面疏水性研究

IF 4.2 3区工程技术

Electric Power Systems Research Pub Date : 2026-06-01 Epub Date: 2026-01-09 DOI: 10.1016/j.epsr.2026.112710

Yuyao Hu , Yulin Wang , Fangbin Liu , Xingliang Jiang , Wentao Jia , Qiang Zhou , Hui Liu

{"title":"Study on surface hydrophobicity of silicone rubber insulator with grating structure based on nanosecond pulse laser processing","authors":"Yuyao Hu , Yulin Wang , Fangbin Liu , Xingliang Jiang , Wentao Jia , Qiang Zhou , Hui Liu","doi":"10.1016/j.epsr.2026.112710","DOIUrl":"10.1016/j.epsr.2026.112710","url":null,"abstract":"<div><div>As the insulation equipment of the power grid, the original contact angle of the silicone rubber of the main material of the composite insulator is about 110°, which does not meet the superhydrophobic standard. To improve the hydrophobicity, a biomimetic superhydrophobic structure, namely the grating micro/nano composite structure of rice leaf, was textured on silicone rubber surface using nanosecond pulsed laser, and the influence of laser technological parameters on the grating microstructure and wetting performance was investigated. Moreover, the chemical elements and functional groups on the surface of silicone rubber before and after laser treatment were tested with an energy dispersive spectrometer and Fourier transform infrared spectroscope. The results show that after laser processing, the grating microstructure and micro / nano particles on the surface of silicone rubber increase the average roughness from 0.6537 μm to 2.5191 μm, and the maximum contact angle is 154.25°. The elemental species on the surface of silicone rubber remain unchanged, but the overall content of carbon and oxygen elements increases, while that of silicon element declines. In summary, the grating microstructure prepared by nanosecond laser can effectively improve the hydrophobicity of the silicone rubber surface, thereby improving the performance of the composite insulator.</div></div>","PeriodicalId":50547,"journal":{"name":"Electric Power Systems Research","volume":"255 ","pages":"Article 112710"},"PeriodicalIF":4.2,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145915240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Risk assessment of cascading failures in wind power DC transmission system based on improved black-winged kite algorithm 基于改进黑翼风筝算法的风电直流输电系统级联故障风险评估

IF 4.2 3区工程技术

Electric Power Systems Research Pub Date : 2026-06-01 Epub Date: 2026-02-09 DOI: 10.1016/j.epsr.2026.112829

Darui Zhu, Wenhao Zhang, Jing Bai, Wanqiao Chen

{"title":"Risk assessment of cascading failures in wind power DC transmission system based on improved black-winged kite algorithm","authors":"Darui Zhu, Wenhao Zhang, Jing Bai, Wanqiao Chen","doi":"10.1016/j.epsr.2026.112829","DOIUrl":"10.1016/j.epsr.2026.112829","url":null,"abstract":"<div><div>The wind power DC transmission system has unparalleled advantages over traditional AC transmission. However, under complex operating conditions, local faults may trigger a series of cascading failures, threatening the safety and stability of the entire system. To comprehensively assess the cascading failure characteristics of the wind power DC transmission system, this paper establishes identification indicators based on the most intuitive and closely related parameters of the transmission line itself to predict fault sequences. Additionally, five system risk assessment indicators: covering load levels, power flow distribution, voltage characteristics, wind power stability, and the interaction effects of the DC system are proposed to evaluate the impact of faults on the system. These indicators require the determination of comprehensive weights, which are calculated using the correlation coefficient method and variation coefficient method for subjective and objective weights, respectively. A linear combination of both weights is then used to establish a deviation minimization objective function, which is solved using the improved Black-winged Kite Algorithm to obtain the comprehensive indicator. The comprehensive identification indicators are applied for line identification to obtain the cascading fault sequence. Subsequently, risk assessment indicators are used to evaluate the severity of the obtained cascading fault sequence. Finally, the improved IEEE39 wind power DC transmission system is used as a test case to perform cascading fault sequence search and risk assessment, validating the feasibility and correctness of the proposed method.</div></div>","PeriodicalId":50547,"journal":{"name":"Electric Power Systems Research","volume":"255 ","pages":"Article 112829"},"PeriodicalIF":4.2,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146188582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Optimization of corona ring design dimensions for extra high-voltage substation bus post insulators using a linear regression approach 用线性回归方法优化特高压变电站母线杆绝缘子电晕环设计尺寸

IF 4.2 3区工程技术

Electric Power Systems Research Pub Date : 2026-06-01 Epub Date: 2026-02-06 DOI: 10.1016/j.epsr.2026.112814

M.Raja Nayak , G. Radhika , M. Saritha , Prabhakara Sharma Pidatala , Pradeep Panthagani , B. Devulal , Harish Sesham

{"title":"Optimization of corona ring design dimensions for extra high-voltage substation bus post insulators using a linear regression approach","authors":"M.Raja Nayak , G. Radhika , M. Saritha , Prabhakara Sharma Pidatala , Pradeep Panthagani , B. Devulal , Harish Sesham","doi":"10.1016/j.epsr.2026.112814","DOIUrl":"10.1016/j.epsr.2026.112814","url":null,"abstract":"<div><div>This study introduces an advanced approach for predicting the optimal dimensions of corona rings in bus post insulators using computational simulations combined with linear regression techniques. Accurate corona ring design is essential to manage this severe electric field stress failing which may lead to insulation failures, energy losses, and decreased system reliability. Although, existing system follow consistent corona ring dimension configuration, further optimization includes abating field stress with reducing ring material size empowers cost effective reliable operation. Thus, optimization of ring dimensions using actual testing approach solely results in expensive choice, while computational simulation-based testing approach aids in arriving optimal ring design dimensions. The goal of this research is to develop empirical relation in systematic approach include sophisticated linear regression machine learning approach to predict the accurate optimal dimensions of corona rings across various voltage levels. Initially, the study employs the precise Boundary Element Method (BEM) in COULOMB 3D software to simulate electric field stress for 400 kV and 765 kV bus post insulators using industry provided design dimensions and arrives optimal ring dimension configuration from multiple case studies. To the optimal ring dimension data generated from these simulations forms the basis for creating a linear regression model. This linear regression model is then applied to predict the corona ring dimensions for further 1200 kV insulators and validated with same 1200 kV BEM simulation data. The key findings underscore the potential of proposed linear regression method to offer scalable, cost-effective solutions for optimizing corona ring dimensions.</div></div>","PeriodicalId":50547,"journal":{"name":"Electric Power Systems Research","volume":"255 ","pages":"Article 112814"},"PeriodicalIF":4.2,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146188585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Vibration-induced micro-discharge at suspension clamp-conductor interfaces under short circuit conditions 短路条件下悬架钳-导体界面振动诱发微放电

IF 4.2 3区工程技术

Electric Power Systems Research Pub Date : 2026-06-01 Epub Date: 2026-01-24 DOI: 10.1016/j.epsr.2026.112772

Chuanyi Zheng , Gengbiao Deng , Beisi Huang , Rui Wang , Deming Guo , Gang Liu

{"title":"Vibration-induced micro-discharge at suspension clamp-conductor interfaces under short circuit conditions","authors":"Chuanyi Zheng , Gengbiao Deng , Beisi Huang , Rui Wang , Deming Guo , Gang Liu","doi":"10.1016/j.epsr.2026.112772","DOIUrl":"10.1016/j.epsr.2026.112772","url":null,"abstract":"<div><div>The conductor at the suspension clamp is always the weak point of the overhead line due to its unique contact structure. When a short circuit occurs, the discharge generated inside the suspension clamp may cause damage to the conductor and lead to serious safety accidents. This article conducted multi contact vibration discharge experiments at the clamp-conductor interfaces. For the first time, microsecond-level observation of vibration discharge inside the clamp has been achieved. Experiments have shown that spark discharge occurs at the clamp-conductor interfaces during dynamic contact separation. Besides, the resistance between contact points is a key factor affecting discharge energy. The energy reduction exceeded 98% for contact discharge and 99% for separation discharge when the resistance between contact points rose from 1.61 mΩ to 8.07 mΩ. The research results of this paper supplement the damage mechanism of conductor at suspension clamps under short circuit current. It provides experimental support for vibration discharge suppression and online monitoring technology inside the clamp.</div></div>","PeriodicalId":50547,"journal":{"name":"Electric Power Systems Research","volume":"255 ","pages":"Article 112772"},"PeriodicalIF":4.2,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A cross-correlation based islanding detection technique using negative sequence injection 负序列注入的互相关孤岛检测技术

IF 4.2 3区工程技术

Electric Power Systems Research Pub Date : 2026-06-01 Epub Date: 2026-02-09 DOI: 10.1016/j.epsr.2026.112805

Chiranjit Biswas , Abanishwar Chakrabarti , Swanirbhar Majumder , Anindita Jamatia

{"title":"A cross-correlation based islanding detection technique using negative sequence injection","authors":"Chiranjit Biswas , Abanishwar Chakrabarti , Swanirbhar Majumder , Anindita Jamatia","doi":"10.1016/j.epsr.2026.112805","DOIUrl":"10.1016/j.epsr.2026.112805","url":null,"abstract":"<div><div>This paper presents a robust islanding detection strategy for grid-connected voltage source converter (VSC) systems. The approach is based on injecting a controlled negative-sequence voltage through the VSC and evaluating the correlation between the injected signal and the negative-sequence voltage measured at the point of common coupling (PCC). Instead of depending on the magnitude of the injected disturbance, the proposed technique relies on the similarity between the two signals, which enables accurate islanding detection even when very small negative-sequence components are used. The use of a correlation-based index also enhances immunity to measurement noise and system disturbances. The effectiveness of the method is validated through detailed simulation and experimental investigations under different load and source variations. Results show that the proposed technique consistently identifies islanding conditions within 1.5 cycles for a 50-Hz power system, demonstrating fast response and high reliability, making it well suited for modern converter-dominated grids.</div></div>","PeriodicalId":50547,"journal":{"name":"Electric Power Systems Research","volume":"255 ","pages":"Article 112805"},"PeriodicalIF":4.2,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Wind power scenario generation via multi-scale condition adaptive diffusion model 基于多尺度条件自适应扩散模型的风电情景发电

IF 4.2 3区工程技术

Electric Power Systems Research Pub Date : 2026-06-01 Epub Date: 2026-01-27 DOI: 10.1016/j.epsr.2026.112753

Jiawei Zhang , Shuhao Liu , Zeyi Shi , Yuancheng Li

{"title":"Wind power scenario generation via multi-scale condition adaptive diffusion model","authors":"Jiawei Zhang , Shuhao Liu , Zeyi Shi , Yuancheng Li","doi":"10.1016/j.epsr.2026.112753","DOIUrl":"10.1016/j.epsr.2026.112753","url":null,"abstract":"<div><div>The large-scale integration of wind power poses significant challenges to power system operation, as the intermittency and stochasticity of wind power generation can adversely affect grid stability. While diffusion models have been applied to wind power scenario generation, their performance remains sensitive due to an inadequate capacity for processing conditional information. To address these issues, this manuscript proposes an multi-scale condition adaptive diffusion model(MS-CADM). Specifically, a multi-scale embedding network is proposed to extract complex conditions at multiple hierarchical levels, while a time step adaptation Transformer architecture is introduced to decouple the time-step condition unique to diffusion models from the external control conditions, which makes model to learn different controllable conditions accurately. During training, a learnable variance term is incorporated to enhance posterior expressiveness, and a random conditional masking strategy is applied for regularization to stabilize training. On Global Energy Forecasting Competition 2014 (GEFCom2014) wind power dataset, MS-CADM reduces MAE by 4.26% and RMSE by 1.91% compared to state-of-the-art methods and achieves competitive performance across six metrics, demonstrating its ability to effectively leverage conditional information and achieve more efficient convergence.</div></div>","PeriodicalId":50547,"journal":{"name":"Electric Power Systems Research","volume":"255 ","pages":"Article 112753"},"PeriodicalIF":4.2,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Spatio-temporal graph fusion framework for accurate city-wide EV charging forecasting 面向城市电动汽车充电预测的时空图融合框架

IF 4.2 3区工程技术

Electric Power Systems Research Pub Date : 2026-06-01 Epub Date: 2026-01-30 DOI: 10.1016/j.epsr.2026.112765

Xufeng Wu , Zuowei Chen , Hefang Jiang , Shoukang Luo , Honghao Liang , Siming Li , Chenyang Xu , Bojin Wang , Wensai Xuan , Yi Zhao , Lin Lin , Hao Wang

{"title":"Spatio-temporal graph fusion framework for accurate city-wide EV charging forecasting","authors":"Xufeng Wu , Zuowei Chen , Hefang Jiang , Shoukang Luo , Honghao Liang , Siming Li , Chenyang Xu , Bojin Wang , Wensai Xuan , Yi Zhao , Lin Lin , Hao Wang","doi":"10.1016/j.epsr.2026.112765","DOIUrl":"10.1016/j.epsr.2026.112765","url":null,"abstract":"<div><div>Accurately forecasting city-wide electric vehicle (EV) charging demand is hindered by complex spatio-temporal dependencies and the static fusion limitations of conventional models. To address these challenges, this paper proposes <strong>DyConfuse-Net</strong>, a novel Dynamic Context-driven Multi-component Hierarchical Fusion Network. DyConfuse-Net overcomes the rigidity of existing hybrid models by integrating four parallel prediction branches: Last Observation (LO), Bi-directional LSTM (BiLSTM), a Fully Connected Network (FCNN), and Differentiated Feature Projection (DFP). The core innovation is a dynamic fusion strategy that adaptively weights the contribution of each branch based on the specific spatio-temporal context of the input data. Experiments on the large-scale UrbanEV benchmark dataset demonstrate that DyConfuse-Net achieves state-of-the-art performance, with a Mean Absolute Percentage Error (MAPE) of 9.680% and a Mean Absolute Error (MAE) of 0.0155, significantly outperforming mainstream approaches. The results validate that our dynamic, hierarchical fusion framework offers a more robust and accurate solution for complex urban energy forecasting tasks.</div></div>","PeriodicalId":50547,"journal":{"name":"Electric Power Systems Research","volume":"255 ","pages":"Article 112765"},"PeriodicalIF":4.2,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Asynchronous learning-based control for power systems with topological disturbances 具有拓扑扰动的电力系统异步学习控制

IF 4.2 3区工程技术

Electric Power Systems Research Pub Date : 2026-06-01 Epub Date: 2026-01-13 DOI: 10.1016/j.epsr.2025.112697

Weidi Cheng , Yanyan Yin , Arindam Ghosh , Shuping He , Yanqing Liu

引用次数: 0