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Fractional order distance regularized level set method with bias correction

The Journal of China Universities of Posts and Telecommunications 2024年第1期31卷 64-82页

作者： Cai Xiumei He Ningning Wu Chengmao Liu Xiao Liu Hang School of Automation Xi'an University of Posts and TelecommunicationsXi'an 710121China School of Electronic Engineering Xi'an University of Posts and TelecommunicationsXi'an 710121China

The existing level set segmentation methods have drawbacks such as poor convergence,poor noise resistance,and long iteration *** this paper,a fractional order distance regularized level set segmentation method with bias correction is *** method firstly introduces fractional order distance regularized term to punish the deviation between the level set function(LSF)and the signed distance *** a series of covering template is constructed to calculate fractional derivative and its conjugate of image *** introducing the offset correction term and fully using the local clustering property of image intensity,the local clustering criterion of image intensity is defined and integrated with the neighborhood center to obtain the global criterion of image ***,the fractional distance regularization,offset correction,and external energy constraints are combined,and the energy optimization segmentation method for noisy image is established by level *** results show that the proposed method can accurately segment the image,and effectively improve the efficiency and robustness of exiting state of the art level set related algorithms.

关键词： image segmentation fractional order distance regularization level set function fractional derivative bias correction

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Voltage Vector Rapid Screening-Based Three-Vector Model Predictive Current Control for Permanent Magnet Synchronous Motor 11th

Voltage Vector Rapid Screening-Based Three-Vector Model Pred...

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11th Frontier Academic Forum of Electrical engineering, FAFEE 2024

作者： Jiang, Youping Yuan, Jiaxin Mao, Zhiyang School of Electrical and Automation Engineering East China Jiaotong University Nanchang330013 China School of Electrical Engineering and Automation Wuhan University Wuhan430072 China

ISBN: (纸本)9789819788231

The permanent magnet synchronous motor's current regulation is predicted using a dual vector model, the current still has a large pulsation because of the limited selection of the second effective vector. To address this issue, discourse provide a voltage vector fast selection based three-vector model predictive current control method for permanent magnet synchronous motors. To cut down on computation and limit control complexity, a quick selection of an efficient voltage vector switching table is created. A voltage vector with an arbitrary direction and amplitude is created by combining the chosen voltage vector with the zero voltage vector. The current ripple is reduced effectively, and the deadbeat control of the direct improves the system's steady-state performance, and quadrature current components simultaneously. The simulation results indicate the validity and usefulness of the proposed technique. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Vectors

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Nanodiamond/Ti_(3)C_(2) MXene-coated quartz crystal microbalance humidity sensor with high sensitivity and high quality factor

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Rare Metals 2024年第6期43卷 2719-2729页

作者： Yao Yao Qiao Chen Yan-Qi Li Xian-He Huang Wei-Wei Ling Zhe-MiaoXie Jia-QiWang Chang-Ming Chen College of Communication Engineering Chengdu University of Information TechnologyChengdu 610225China School of Automation Chongqing University of Posts and TelecommunicationsChongqing 400065China School of Automation Engineering University of Electronic Science and Technology of ChinaChengdu 611731China Advanced Micro-/Nano-Devices Lab Department of Systems Design EngineeringUniversity of WaterlooWaterlooON N2L 3GlCanada

To address the challenge of achieving both high sensitivity and a high quality factor in quartz crystal microbalance(QCM)humidity sensors,a nanodiamond(ND)/Ti_(3)C_(2)MXene composite-coated QCM humidity sensor was *** material characteristics of ND,Ti_(3)C_(2)MXene,and ND/Ti_(3)C_(2)MXene composite were analyzed by transmission electron microscopy(TEM)and Fourier transform infrared(FTIR)*** experimental results demonstrated that the hydrophilic ND nanoparticles coated on Ti_(3)C_(2) MXene nanosheet prevented the self-stacking of Ti_(3)C_(2)MXene and enhanced the sensitivity of Ti_(3)C_(2) MXene-based QCM humidity ***,the high mechanical modulus of Ti_(3)C_(2) MXene material helped ND/Ti_(3)C_(2)MXene composite-coated QCM humidity sensor to achieve a high quality factor(>20,000).ND/Ti_(3)C_(2)MXene compositecoated QCM humidity sensor exhibited a sensitivity of 82.45 Hz/%RH,a humidity hysteresis of 1.1%RH,fast response/recovery times,acceptable repeatability,and good stability from 11.3%RH to 97.3%*** response mechanism of ND/Ti_(3)C_(2) MXene composite-coated QCM humidity sensor was analyzed in combination with a bi-exponential kinetic adsorption ***,the potential application of ND/Ti_(3)C_(2)MXene composite-coated QCM humidity sensor was demonstrated through its frequency response to wooden blocks with different moisture contents.

关键词： Humidity sensor Quartz crystal microbalance Nanodiamond Ti_(3)C_(2)MXene High quality factor

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Electromagnetic disturbance characteristic of typical high voltage switchgear interruption process in offshore wind farm based on integrated conduction model

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High Voltage 2023年第5期8卷 907-920页

作者： Huaqing Wang Daochun Huang Mingjing Shuang Huipeng Li Yiqun Qiu Engineering Research Center of Ministry of Education for Lightning Protection and Grounding Technology Wuhan UniversityWuhanChina School of Electrical Engineering and Automation Wuhan UniversityWuhanChina

In an offshore wind farm,a high‐voltage switchgear interruption in an offshore substation creates a high‐frequency,high‐amplitude overvoltage that can cause severe electromagnetic interference problems in the intelligent electronic *** address this issue,mathematical models,vector fitting and finite element method were used to build an integrated electromagnetic disturbance conduction model,whose accuracy was verified by large current interruption *** the simulation of a typical offshore wind farm's single‐phase grounding fault interruption process,the electromagnetic disturbance characteristics and the impact of the ground position are *** results show that during the fault interruption process of phase B grounded,the dominant frequency of disturbance voltage can reach 4.34 MHz,and the amplitude can reach 1.12 *** ground grid has a large impact on the interference voltage,which can reach a maximum value of 2.28 kV under specific *** disturbance voltage in the fault process mainly comes through the current transformer,while during the interruption process,it mainly comes through the ground *** authors provide a method to establish the integrated electromagnetic disturbance simulation model,which can improve the accuracy of the electromagnetic disturbance conduction process simulation of intelligent components.

关键词： offshore fault disturbance

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Trajectory Tracking Control of Nonholonomic Wheeled Mobile Robots Based on Event-Triggered and Time-Varying Functions 9

Trajectory Tracking Control of Nonholonomic Wheeled Mobile R...

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9th International Symposium on Computer and Information Processing Technology, ISCIPT 2024

作者： Li, Gaohan Fan, Yuan Guo, Yuchao Anhui University School of Electrical Engineering and Automation China

ISBN: (纸本)9798350388404

In this work, we study the trajectory-tracking control problem of the nonholonomic wheeled mobile robot and propose an event-triggered control method based on the control system, which enables the robot's motion trajectory to be sufficiently smooth and capable of quickly tracking the desired trajectory, while greatly reducing the update frequency of the system and saving computational resources. Firstly, a unified mathematical model is constructed based on the tracking problem, and a controller based on a time-varying function is selected. This controller enables the robot to obtain a smoother autonomous motion trajectory, and a faster convergence rate, and can achieve desired trajectory tracking well. Then, we propose an event-triggered control method based on this, which can significantly reduce the update frequency without affecting the speed and stability of the system. Finally, it is proved that the system is stable, and the solution of it is uniformly asymptotically stable and ultimately bounded. It is proved that the system does not have Zeno behavior. Simulations verify the feasibility and effectiveness of the proposed method. © 2024 IEEE.

关键词： Mobile robots

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Bionic Design and Analysis of a Novel Quadruped Robot with a Multistage Buffer System

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Chinese Journal of Mechanical engineering 2022年第2期35卷 56-76页

作者： Yi Zheng Kun Xu Yaobin Tian Huichao Deng Xilun Ding School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China

Large quadruped mammals,such as ruminants,have outstanding motion ability,including running and *** advanced motion abilities are related to the buffer effect of their complicated musculoskeletal ***,the buffer effect of most bio-robots is not satisfactory owing to the simple design of their buffer *** this paper,a physiological analysis of the ruminant musculoskeletal system is presented to explain the intrinsic buffer mechanism of *** on the physical buffer parts of the ruminant limbs,the corresponding bionic mappings were *** mappings were used to guide the mechanism design of the robot multistage buffer *** multistage buffer system includes two main buffer mechanisms:the first stage and the second *** buffer mechanism analysis of the first stage and multiple stages is discussed in theory to compare the effects between the normal single buffer system and the novel multistage buffer ***,the detailed mechanical structure of the limbs was designed based on the limb mechanism *** further verify the superior efficacy of the multistage buffer system,the corresponding walking simulation experiments were conducted after the virtual prototype of a quadruped robot with a novel limb was built *** theoretical analysis and simulation experiments prove that the bionic robot design with the novel multistage buffer system achieves better motion performance than the traditional robot buffer design and can be regarded as the design template of the robot limb.

关键词： Ruminant musculoskeletal system Bioinspired multistage buffer system Mechanism design Robotics Quadruped robot

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Effect of pouring time on microstructure and mechanical properties of centrifugal cast Ti-46Al alloy tubes

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China Foundry 2025年第1期22卷 65-74页

作者： Gang Huang Qian Dang Cong-cong Su Jing Zhao Chi Zhang Guo-huai Liu Zhao-dong Wang The State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China

The grain size of TiAl alloy castings prepared by traditional casting process is coarse,thus showing poor mechanical *** this study,a new type of high performance Ti-46Al alloy tube prepared by vacuum centrifugal casting technology was *** research comprehensively examined the influence of pouring time on the microstructure and mechanical performance of the castings,employing both experimental approaches and ProCast simulation *** findings indicate that prolonging the pouring time facilitates a microstructural evolution from coarse columnar grains to refined equiaxed *** the condition of pouring temperature of 1,600℃,rotation speed of 800 r·min^(-1) and pouring time of 6 s,the tensile strength of Ti-46Al alloy at room temperature reaches 650 MPa,and the tensile strength at 800℃ reaches 705 MPa,which is significantly higher than that of traditional as-cast Ti-Al alloy.

关键词： vacuum induction melting centrifugal casting Ti-46Al alloy pouring time Ti-Al alloy tubes

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Dynamics modeling and error analysis for antenna pointing mechanisms with frictional spatial revolute joints on SE(3)

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Chinese Journal of Aeronautics 2022年第8期35卷 265-279页

作者： Long LI Shengnan LYU Xilun DING School of Mechanical Engineering and Automation Beihang UniversityBeijing 100083China

This paper presents a non-smooth multibody dynamic formulation and error analysis of an antenna pointing mechanism including frictional spatial revolute joints(FSRJs)with small clearance in the framework of the special Euclidian group SE(3).The formulation leads to an inertial frame-invariant,a compact and unified description for rigid bodies and spatial revolute joints(SRJs).The geometric constraint of the bearing is covered by four open semi-cylinders,which can be treated as bilateral constraints assuming that the impact effects are *** frictional contact problem is formulated as a horizontal linear complementary problem(HLCP),which is embedded in the Lie-group integration *** of the antenna pointing mechanism is modeled by means of the adjoint transformation and POE-based *** evolution of errors is obtained through the solution of non-smooth *** obtained numerical results illustrate the influences of FSRJs in dynamics modeling and error analysis of the antenna pointing mechanism.

关键词： LCP Lie-group integration Mechanism error analysis Non-smooth dynamics Spatial revolute joints

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Research on Unmanned Aerial Vehicle Attitude Estimation Algorithm Based on Monocular Vision 43

Research on Unmanned Aerial Vehicle Attitude Estimation Algo...

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43rd Chinese Control Conference, CCC 2024

作者： Zhang, Wei Dong, Wanlong Ma, Fengying Ji, Peng School of Information and Automation Engineering Jinan250000 China

ISBN: (纸本)9789887581581

The detection and pose estimation of targets are crucial for many applications of unmanned aerial vehicles, with one of the important applications being the completion of ground moving target tracking tasks. This paper addresses the problem of target detection and relative pose estimation for unmanned aerial vehicle target tracking, proposing a monocular vision-based UAV pose estimation method. The method constructs a pose estimation system using target QR code features and a monocular camera. It employs a QR code feature point detection algorithm to extract QR code feature point information and utilizes the Zhang camera calibration algorithm to calibrate camera intrinsic and distortion parameters. The monocular camera's pose estimation is achieved based on the mapping relationship between feature point pixel coordinates and actual coordinates in the world coordinate system. Through experiments estimating the target pose from the UAV's viewpoint, this method accurately estimates the relative position and attitude of the UAV with respect to the target, satisfying subsequent tracking requirements. © 2024 Technical Committee on Control Theory, Chinese Association of automation.

关键词： Aircraft detection

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A Novel Fault Diagnosis Method for Main Circulation Pump of VSC-HVDC Valve Cooling System Based on CWT and Dilated 2DCNN 24

A Novel Fault Diagnosis Method for Main Circulation Pump of ...

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2024 International Conference on Machine Learning, Pattern Recognition and automation engineering, MLPRAE 2024

作者： Zhou, Sihan Liu, Haofeng He, Min Qin, Liang School of Electrical Engineering and Automation Wuhan University China

ISBN: (纸本)9798400709876

Main circulation pumps play a vital role in VSC-HVDC systems cooling process. Current solutions for unattended operation and maintenance of these pumps are underdeveloped, and fault diagnosis research is limited. To address this issue, this paper presents a fault diagnosis model for the main circulation pump of a VSC-HVDC cooling system using continuous wavelet transform (CWT) and dilated 2D convolutional neural networks (2DCNN). CWT converts one-dimensional time-series vibration data into two-dimensional time-frequency images, which retain both time-domain and frequency-domain information and are processed by a dilated 2DCNN to enhance fault detection accuracy. Experiments demonstrate that the proposed method achieves higher evaluation metrics compared to other methods, with an accuracy of 95.20%, precision of 95.22%, recall of 95.20%, and F1 score of 95.20%, providing a data-driven fault diagnosis tool for on-site operation, maintenance, and planned repairs of the main circulation pump. © 2024 ACM.

关键词： Frequency domain analysis

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