检索结果-内蒙古大学图书馆

arXiv 2023年

作者： Liu, Xiaogeng Li, Minghui Wang, Haoyu Hu, Shengshan Ye, Dengpan Jin, Hai Wu, Libing Xiao, Chaowei School of Cyber Science and Engineering Huazhong University of Science and Technology China School of Computer Science and Technology Huazhong University of Science and Technology China School of Software Engineering Huazhong University of Science and Technology China National Engineering Research Center for Big Data Technology and System China Services Computing Technology and System Lab China Hubei Key Laboratory of Distributed System Security China Hubei Engineering Research Center on Big Data Security China Cluster and Grid Computing Lab China School of Cyber Science and Engineering Wuhan University China Arizona State University United States

Deep neural networks are proven to be vulnerable to backdoor attacks. Detecting the trigger samples during the inference stage, i.e., the test-time trigger sample detection, can prevent the backdoor from being triggered. However, existing detection methods often require the defenders to have high accessibility to victim models, extra clean data, or knowledge about the appearance of backdoor triggers, limiting their practicality. In this paper, we propose the test-time corruption robustness consistency evaluation (TeCo)1, a novel test-time trigger sample detection method that only needs the hard-label outputs of the victim models without any extra information. Our journey begins with the intriguing observation that the backdoor-infected models have similar performance across different image corruptions for the clean images, but perform discrepantly for the trigger samples. Based on this phenomenon, we design TeCo to evaluate test-time robustness consistency by calculating the deviation of severity that leads to predictions' transition across different corruptions. Extensive experiments demonstrate that compared with state-of-the-art defenses, which even require either certain information about the trigger types or accessibility of clean data, TeCo outperforms them on different backdoor attacks, datasets, and model architectures, enjoying a higher AUROC by 10% and 5 times of stability. Copyright © 2023, The Authors. All rights reserved.

关键词： Crime

来源：评论

学校读者我要写书评

暂无评论

PointCA: Evaluating the Robustness of 3D Point Cloud Completion Models Against Adversarial Examples

arXiv

引用

arXiv 2022年

作者： Hu, Shengshan Zhang, Junwei Liu, Wei Hou, Junhui Li, Minghui Zhang, Leo Yu Jin, Hai Sun, Lichao School of Cyber Science and Engineering Huazhong University of Science and Technology China School of Computer Science and Technology Huazhong University of Science and Technology China School of Software Engineering Huazhong University of Science and Technology China Cluster and Grid Computing Lab China National Engineering Research Center for Big Data Technology and System Hubei Engineering Research Center on Big Data Security China Hubei Key Laboratory of Distributed System Security China Services Computing Technology and System Lab China City University of Hong Kong Hong Kong Deakin University Australia Lehigh University United States

Point cloud completion, as the upstream procedure of 3D recognition and segmentation, has become an essential part of many tasks such as navigation and scene understanding. While various point cloud completion models have demonstrated their powerful capabilities, their robustness against adversarial attacks, which have been proven to be fatally malicious towards deep neural networks, remains unknown. In addition, existing attack approaches towards point cloud classifiers cannot be applied to the completion models due to different output forms and attack purposes. In order to evaluate the robustness of the completion models, we propose PointCA, the first adversarial attack against 3D point cloud completion models. PointCA can generate adversarial point clouds that maintain high similarity with the original ones, while being completed as another object with totally different semantic information. Specifically, we minimize the representation discrepancy between the adversarial example and the target point set to jointly explore the adversarial point clouds in the geometry space and the feature space. Furthermore, to launch a stealthier attack, we innovatively employ the neighbourhood density information to tailor the perturbation constraint, leading to geometry-aware and distribution-adaptive modification for each point. Extensive experiments against different premier point cloud completion networks show that PointCA can cause a performance degradation from 77.9% to 16.7%, with the structure chamfer distance kept below 0.01. We conclude that existing completion models are severely vulnerable to adversarial examples, and state-of-the-art defenses for point cloud classification will be partially invalid when applied to incomplete and uneven point cloud data. Copyright © 2022, The Authors. All rights reserved.

关键词： Deep neural networks

来源：评论

学校读者我要写书评

暂无评论

Assessment on Transient Reactive Power Capability of a Grid-Connected Synchronous Condenser

Assessment on Transient Reactive Power Capability of a Grid-...

引用

International Conference on Electrical Machines and systems (ICEMS)

作者： Jianfu Li Hui Li Wang Xiao Bin Yuan Youbin Zhou Tao Wang Guanghou Zhou State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing China State Grid Hubei Electric Power Company Electric Power Research Institute Hubei China Dongfang Electric Machinery Co. Ltd Deyang China

ISBN: (纸本)9781728133997

New generation of large-capacity synchronous condensers (SC) is used in ultrahigh-voltage direct current (UHVDC) engineering. It aims to improve the commutation failure of DC system and suppress the transient over-voltage of the system by using its dynamic reactive characteristics. Therefore, it is necessary to accurately evaluate the transient reactive output capability of the SC. Firstly, based on the mathematical model of SC, the transient reactive power expression in the grid fault is deduced. Secondly, the saturation of the SC parameters, the steady-state reactive power, and the degree of grid voltage change are analyzed. Finally, the SC simulation model is established based on the actual SC electromagnetic parameters, and its transient reactive output characteristics are simulated and compared with the theoretical analysis results. The results show that the transient reactive power output of the SC will increase when parameters become saturated. The output transient reactive power increment of the SC increases with the increase of the surge degree of power grid voltage. The output transient reactive power increment of the SC increases and then decreases with the drop degree of power grid voltage. It can provide more effective reactive power support for the system when the steady-state operation of the SC is in phase advance and when the power grid fails.

关键词： Transient analysis Reactive power Mathematical model Windings Steady-state Stator windings

来源：评论

学校读者我要写书评

暂无评论

Modulation of Switching Current Density in T-Type Magnetic Structure Through Magnetic Anisotropy

SSRN

引用

SSRN 2023年

作者： Li, Peizhi Wu, Chuangwen Zhou, Xiangqing Ren, Chuantong Cao, Cuimei Su, Yurong Chen, Shiwei Liang, Shiheng School of Physics Hubei University Wuhan430062 China School of Integrated Circuits Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan430074 China Key Laboratory for Intelligent Sensing System and Security of Ministry of Education Wuhan430062 China

We investigate magnetic field driven domain wall motion and spin-orbit torque (SOT) induced perpendicular magnetization switching of the ferrimagnetic layer in a T-type magnetic heterojunction with the structure of Pt/Co/Ta/Co81Tb19/Ta, where the bottom Co layer has in-plane magnetic anisotropy and the top Co81Tb19 layer has perpendicular magnetic anisotropy. SOT-induced perpendicular magnetization switching of the Co81Tb19 layer is observed. A lower critical switching current density was obtained at the optimized thickness (tCo = 1.2 nm), resulting in a 37% reduction in critical switching current density. Meanwhile, the research reveals a strong correlation between critical switching current density and magnetic anisotropy field, indicating that tuning the magnetic anisotropy is an efficient way to modulate the switching current density in a T-type magnetic structure. These results provide a new perspective on SOT manipulation and will be useful for the design of SOT-based devices. © 2023, The Authors. All rights reserved.

关键词： Binary alloys

来源：评论

学校读者我要写书评

暂无评论

Experimental and simulation analysis of the influence of moisture on dielectric and breakdown properties of insulation pressboard used in power transformer 3

Experimental and simulation analysis of the influence of moi...

引用

2020 3rd International Conference on Mechatronics and Computer Technology Engineering, MCTE 2020

作者： Wen, Hao Cheng, Lin Jiang, Yi Zhao, Zhigang Ye, Wenyu Hao, Jian Nanjing Nari Group Corp. State Grid Electric Power Research Institute Nanjing Jiangsu211000 China Wuhan Nari Co Ltd. State Grid Electric Power Research Institute Wuhan Hubei430074 China China Electric Power Research Institute Beijing100192 China State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing University Chongqing400044 China

The influence of water molecules on cellulose has attracted much attention. The influence of water molecules on the dielectric property and breakdown property of cellulose requires in-depth research. In this paper, firstly, the effect of water on the dielectric spectrum in the frequency domain dielectric spectrum and the breakdown voltage of cellulose were studied. Then the parameters such as free volume, hydrogen bond, energy level and state density of cellulose under different moisture content were analysed by molecular simulation. The changes of dielectric properties and breakdown properties of cellulose under different water content were studied and summarized. The variation mechanism of dielectric property and breakdown property of different moisture content was explained by molecular simulation. © Published under licence by IOP Publishing Ltd.

关键词： Cellulose

来源：评论

学校读者我要写书评

暂无评论

Tensor Dynamic Fusion Based Modality-Imbalanced Multimodal Federated Learning in Mobile Edge Computing for Consumer Applications

引用

IEEE Transactions on Consumer Electronics 2024年

作者： Nie, Xin Yi, Lingzhi Yang, Laurence T. Deng, Xianjun Fan, Fulan Zhang, Hongtao Huazhong University of Science and Technology Hubei Key Laboratory of Distributed System Security Hubei EngineeringResearch Center on Big Data Security School of Cyber Science and Engineering Wuhan430074 China Zhongnan University of Economics and Law School of Information and Safety Engineering Wuhan430074 China Huazhong University of Science and Technology School of Computer Science and Technology Wuhan China Zhengzhou University School of Computer and Artificial Intelligence Zhengzhou China St. Francis Xavier University Department of Computer Science Antigonish Canada South-Central Minzu University School of Education Wuhan430074 China

Mobile edge computing extends the capabilities of computation and storage from the cloud to the edge, enabling local data storage and processing. This computing paradigm complements federated learning (FL), as it satisfies the need for privacy protection while providing efficiency and quick response. In consumer applications, multimodal data is experiencing explosive growth. Therefore, multimodal FL has emerged as a crucial research area. However, applying traditional FL methods directly to multimodal data poses certain challenges. Additionally, issues like sensor failures result in modality-imbalanced data among clients, i.e., the number and type of data modalities between client devices vary. Hence, it is imperative to design specialized FL frameworks and models specifically tailored for analyzing multimodal data. To address these challenges, we propose a tensor fusion-based multimodal federated learning (TenMFL). First, a tensor dynamic fusion network is designed for addressing the challenge of multimodal data fusion. This approach separates the parameter forward computation and the modal fusion computation, effectively resolving issues related to client-side modality imbalance. Second, we introduce a hybrid fusion method that combines feature fusion and decision fusion to further exploit the complementarity of multimodal data. We evaluate TenMFL on three multimodal datasets, experimental results demonstrate our superior performances. © 1975-2011 IEEE.

关键词： Federated learning

来源：评论

学校读者我要写书评

暂无评论

Study on modelling and its parameter identification method of doubly-fed wind turbines LVRT based on measured power response curves

Study on modelling and its parameter identification method o...

引用

12th International Conference on Renewable Power Generation (RPG 2023)

作者： L. Jia X. Peng J. He S. Li F. Miao Hubei Key Laboratory of Power Equipment & System Security for Integrated Energy School of Electrical Engineering and Automation Wuhan University People's Republic of China China Electric Power Research Institute Beijing People's Republic of China

With the increasingly prominent energy and environmental problems, wind power generation with its advantages of clean, flexible, sustainable and other advantages in the grid account for an increasing *** is important to study the electromechanical transient model of wind turbine low voltage ride-through (LVRT) and its modeling method based on the measured data to improve the analysis results of the transient response characteristics of wind power grid-connected system to voltage faults. In this paper, based on Doubly-Fed Induction Generator (DFIG), firstly, the dynamic regulation process of converter and generator is ignored, and based on the electromechanical transient model of wind turbine active-reactive power regulation command to stator output active-reactive current respectively, the typical active-reactive power control mode of wind turbine LVRT is studied according to the measured power response curve of LVRT, and the active-reactive power limitation strategy during LVRT. The typical active-reactive power control method of LVRT and the active-reactive power limiting strategy during LVRT are investigated. Then, a method is proposed to identify the fault ride-through control strategy using the characteristic points of the power, voltage and current response curves of the measured voltage fault ride-through. Based on analyzing the main control parameters of the model with the parameter sensitivity, an optimization method based on the least square method is proposed to identify the model parameters step by step. Finally, the validity of the model and the identification method are verified by using Matlab/Simulink simulation and real measurement data, and the robustness of the model is verified by using operating conditions with different degrees of voltage dips.

关键词：

来源：评论

学校读者我要写书评

暂无评论

An Improved End-Winding Leakage Inductance Calculation Method Based on Frozen Permeability for Large Synchronous Condenser

An Improved End-Winding Leakage Inductance Calculation Metho...

引用

International Conference on Electrical Machines and systems (ICEMS)

作者： Jianfu Li Hui Li Youbin Zhou Tao Wang Bin Yuan Wang Xiao Guanghou Zhou State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing China Electric Power Research Institute State Grid Hubei Electric Power Company Wuhan Hubei China Dongfang Electric Machinery Co. Ltd Deyang Sichuan China

ISBN: (纸本)9781728133997

New and large synchronous condensers (SC) are required to improve the sub-transient voltage stability on the high voltage DC transmission, and the leakage inductance accurate calculation of SC is vital to meet the grid requirements. An improved end leakage inductance calculation method based on frozen permeability was proposed. Firstly, the end leakage inductance separation method by using 2D/3D finite element analysis was presented. Secondly, according to the actual structure of a 300 Mvar SC, 2D and 3D end FEA models were established respectively to analyze the magnetic saturation distribution in different operational states. Finally, the end leakage inductance under the different operation conditions was calculated and compared with the conventional method. The results show that to calculate the end-winding leakage inductance of SC, the effect of magnetic saturation and the rotor position should be considered, especially in the transient condition, and the saturation distribution of d and q-axis are also different under different working conditions.

关键词： Inductance Permeability Stator cores Three-dimensional displays Solid modeling Windings

来源：评论

学校读者我要写书评

暂无评论

Structural disorder-induced topological phase transitions in quasicrystals

arXiv

引用

arXiv 2024年

作者： Peng, Tan Xiong, Yong-Chen Hua, Chun-Bo Liu, Zheng-Rong Zhu, Xiaolu Cao, Wei Lv, Fang Hou, Yue Zhou, Bin Wang, Ziyu Xiong, Rui Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education School of Physics and Technology Wuhan University Wuhan430072 China Hubei Key Laboratory of Energy Storage and Power Battery School of Mathematics Physics and Optoelectronic Engineering Hubei University of Automotive Technology Shiyan442002 China School of Electronic and Information Engineering Hubei University of Science and Technology Xianning437100 China Department of Physics Hubei University Wuhan430062 China The Institute of Technological Science Wuhan University Wuhan430072 China Key Laboratory of Intelligent Sensing System and Security of Ministry of Education Hubei University Wuhan430062 China

Recently, the structural disorder-induced topological phase transitions in periodic systems have attracted much attention. However, in aperiodic systems such as quasicrystalline systems, the interplay between structural disorder and band topology is still unclear. In this work, we investigate the effects of structural disorder on a quantum spin Hall insulator phase and a higher-order topological phase in a two-dimensional Amman-Beenker tiling quasicrystalline lattice, respectively. We demonstrate that the structural disorder can induce a topological phase transition from a quasicrystalline normal insulator phase to an amorphous quantum spin Hall insulator phase, which is confirmed by bulk gap closing and reopening, robust edge states, quantized spin Bott index and conductance. Furthermore, the structural disorder-induced higher-order topological phase transition from a quasicrystalline normal insulator phase to an amorphous higher-order topological phase characterized by quantized quadrupole moment and topological corner states is also found. More strikingly, the disorder-induced higher-order topological insulator with eight corner states represents a distinctive topological state that eludes realization in conventional crystalline systems. Our work extends the study of the interplay between disorder effects and topologies to quasicrystalline and amorphous systems. Copyright © 2024, The Authors. All rights reserved.

关键词： Topology

来源：评论

学校读者我要写书评

暂无评论

An operational strategy of variable speed pumped storage units considering system flexibility

An operational strategy of variable speed pumped storage uni...

引用

12th International Conference on Renewable Power Generation (RPG 2023)

作者： W. Lv X. Peng T. Shi H. Zhao B. Wang Q. Xu Hubei Key Laboratory of Power Equipment & System Security for Integrated Energy School of Electrical Engineering and Automation Wuhan University Wuhan People's Republic of China State Grid Hubei Province Power Company No.197 Xudong street Hongshan District Wuhan People's Republic of China

With the continuous increase in the installed capacity proportion of new energy units, the volatility and uncertainty of their output pose a great challenge to the flexibility of the power system. Compared with conventional pumped storage units (CPSU), variable-speed pumped storage units (VSPSU) have a wider operating range and higher efficiency. In order to clarify the advantages of VSPSU in typical application scenarios, this paper conducts research on how to use VSPSU to improve power system flexibility. Power system flexibility refers to the ability of a power system to quickly respond to significant fluctuations in supply or load. Thus, this paper firstly introduces a power system flexibility calculation method considering uncertainty and converts it into corresponding economic benefit indicators. Secondly, based on the structural characteristics of VSPSU, the operational constraint equations are confirmed. Then, considering the operational cost, its impact on system flexibility and the operation constraints, a day-ahead dispatching operation strategy of VSPSU is proposed using the bacterial colony chemotaxis algorithm under the scenario of a high proportion of new energy units. By adjusting the operation conditions and output power of VSPSU, the effect of suppressing system power fluctuations can be achieved.

关键词：

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：