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Performance Analysis of Corroded Grounding Devices with an Accurate Corrosion Model

CSEE Journal of Power and Energy systems 2023年第3期9卷 1235-1247页

作者： Yihua Dan Zhanlong Zhang Pengfei Gan Huarui Ye Qiaoyi Li Jun Deng State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqing 400030China Test Centre of EHV Transmission Company China Southern Power GridGuangzhou 510663China

Grounding devices are significant to the operation of the power transmission line and power *** soil and leakage current can easily cause the corrosion of carbon steel grounding devices,resulting in power ***,most carbon steel grounding devices in service are already corroded,and the accurate calculation of grounding parameters for corroded grounding devices is ***,most existing methods for calculating the grounding parameters of corroded grounding devices usually have the following disadvantages:1)They only consider whether the grounding devices are broken or not,and cannot analyze the grounding parameters of grounding devices with different corrosion degrees;2)They assume that the corroded grounding device is a conductor with a smaller diameter,and ignore the impact of the corrosion product layer,resulting in calculation *** solve the above problems,this paper establishes an accurate corrosion model for grounding devices based on the volume expansion coefficient of corrosion *** grounding parameters calculation method for corroded grounding devices is proposed based on the boundary element method(BEM)and Galerkin’s *** the grounding performance of tower grounding grids with different corrosion degrees in different soils(uniform and layered)is ***,some features of grounding parameters of corroded grounding devices are *** study can accurately calculate the grounding parameters of the corroded grounding devices and has far-reaching engineering significance for the safety of power equipment.

关键词： Corroded grounding devices corrosion product layer grounding parameters volume expansion coefficient

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Research Status and Trends of Indoor Positioning and Navigation technology in China

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Journal of Geodesy and Geoinformation Science 2023年第3期6卷 87-101页

作者： Baoguo YU Lu HUANG Yachuan BAO Haonan JIA Shuang LI Chong CHEN Academy for Network&Communications of CETC Shijiazhuang 050081China State Key Laboratory of Satellite Navigation System and Equipment Technology Shijiazhuang 050081China

As an essential component of future comprehensive Positioning,Navigation,and Timing(PNT)system,indoor positioning technology has extensive application demands,making it a focal point of attention in both academia and *** article comprehensively reviews the research status of indoor positioning technology in China,with a focus on highlighting representative achievements and application validations from major research institutions in recent *** addresses the challenges and issues faced in promotion and application of large-scale,high-precision indoor ***,a universal and seamless indoor-outdoor positioning system architecture is proposed,along with a technical roadmap and key technologies to achieve this ***,an analysis and outlook on future technological trends are presented.

关键词： indoor positioning location services integrated PNT

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Dynamic synchronous motion accuracy measurement and estimation for a five-axis mirror milling system

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Science China(Technological Sciences) 2023年第3期66卷 689-705页

作者： XU Kun TANG XinYu BI QingZhen YU YangBo QIAN DeHou JI YuLei State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Shanghai TOP Numerical Control Technology Co. Ltd.Shanghai 201100China

A mirror milling system(MMS)comprises two face-to-face five-axis machine tools,one for the cutting spindle and the other for the support *** it is essential to maintain the cutter and support coaxial during the cutting process,synchronous motion accuracy is the key index of the *** paper proposed a novel method for measuring and estimating the synchronous motion accuracy of the dual five-axis machine *** method simultaneously detects errors in the tool center point(TCP)and tool axis direction(TAD)during synchronous *** implement the suggested method,a measurement device,with five high-precision displacement sensors was developed.A kinematic model was then developed to estimate the synchronous motion accuracy from the displacement sensor *** screw theory was used to obtain the analytical expression of the inverse kinematic model,and the synchronous motion error was compensated and adjusted based on the inverse kinematic model of the dual five-axis machine *** and TAD quasi-static errors,such as geometric and backlash errors,were first *** adjusting the servo parameters,the dynamic TCP and TAD errors,such as gain mismatch and reversal spike,were also *** proposed method and device were tested in a large MMS,and the measured quasi-static and dynamic errors were all reduced when the compensation and adjustment method was *** Carlo simulations were also used to estimate the uncertainty of the proposed scheme.

关键词： mirror milling synchronous motion error five-axis machine tool measurement dynamic accuracy

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High accuracy target point classification through dark-field detection of large-aperture optics surface based on machine vision

High accuracy target point classification through dark-field...

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2024 Applied Optics and Photonics China: Optical Sensing, Imaging technology, and Applications, AOPC 2024

作者： Zhou, Shicheng Yin, Zhaoyang Wang, Bei Zhao, Linjie Cheng, Jian Chen, Mingjun School of Mechatronics Engineering Harbin Institute of Technology Harbin150001 China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China

ISBN: (数字)9781510687820

ISBN: (纸本)9781510687813

Surface defects on optics seriously affect their service life in high-power laser system. To address this issue, repair technologies for large-aperture optics are extensively employed. However, the operation of high-power laser system generates a large number of optics requiring repair. Currently, microscopic inspection is widely used for target points classification due to its high accuracy, but it has limitations such as small field of view and low efficiency. Utilizing the OTSU algorithm and Convolutional Neural Networks (CNN), a dark-field classification model for optical surface target points has been developed. Upon conducting experiments with several network models, the ResNet model, a probability threshold of 0.998 were determined. In conclusion, the classification accuracy for defects was 99.18% and for contaminants was 90.34%. The outcomes show that target points on the surfaces of optics can be accurately classified using this method. © 2024 SPIE.

关键词： Machine vision

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An insight into the pass effect of the planet gear from an elastodynamics perspective

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Science China(Technological Sciences) 2023年第8期66卷 2415-2431页

作者： HUANGFU YiFan DONG XingJian CHEN KangKang LI ZhanWei PENG ZhiKe Institute of Vibration Shock and NoiseState Key Laboratory of Mechanical System and VibrationShanghai Jiao Tong UniversityShanghai 200240China National Key Laboratory of Science and Technology on Helicopter Transmission Nanjing University of Aeronautics and AstronauticsNanjing 210016China School of Mechanical Engineering Ningxia UniversityYinchuan 750021China

Distinguished from parallel-axis gear systems,the revolution of the carrier brings out the pass effect of the planet *** with the phenomenological descriptions in conventional studies,this paper aims to provide more abundant physical information and the elastodynamics mechanism of the pass effect of the planet *** this end,a continuous-discrete model of helical planetary gears is *** both the in-plane and out-of-plane vibration,a semi-analytical model is established to simulate the elastic ring *** elastic and the lumped parameter submodels are synthesized using the moving elastic coupling *** simulated modal and dynamic characteristics are verified using a planetary gear test *** on the proposed dynamic model,the pass effect of the planet gear,the effects of bolt constraint,and the out-of-plane vibration of helical planetary gears are *** is revealed that the“realistic rotation”strategy adopted in the proposed dynamic model can better reflect the physical essence of the pass effect of the planet gear compared with the“pseudo rotation”strategy utilized in the traditional model.

关键词： planetary gear elastodynamics pass effect semi-analytical model dynamic characteristics

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An Unbalance Identification Method of a Whole Aero-Engine Based on the Casing Vibrations 11th

An Unbalance Identification Method of a Whole Aero-Engine Ba...

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11th IFToMM International Conference on Rotordynamics, IFToMM 2023

作者： Wang, Weimin Wang, Jiale Li, Qihang Beijing Key Laboratory of Health Monitoring and Self-Recovery for High-End Mechanical Equipment Beijing University of Chemical Technology Beijing100029 China State Key Laboratory of High-End Compressor and System Technology Beijing China

ISBN: (纸本)9783031404580

Squeeze film dampers (SFDs) have been frequently employed in aero-engines due to their excellent vibration reduction performance. However, their nonlinear characteristics make it difficult for traditional balancing methods to achieve efficient vibration suppression. In addition, because of the harsh condition and restricted space inside the casing, sensors are only able to be installed on the surface of the casing to evaluate the operational state of an aero-engine. Therefore, it is vital to propose an unbalance identification method of a whole aero-engine with SFDs. In this paper, the equivalent unbalance calculation equation, which takes the vibration transfer characteristics of the casing, nonlinear oil film forces, the flexible support and gyroscopic moments into account, is derived by decoupling the differential equation of rotor motion in modal coordinates. The equivalent unbalance distribution of the rotor is generated by solving very ill-conditioned linear equations produced by modal parameters. Finally, a nonlinear unbalance identification method based on casing vibrations is developed. By establishing a whole aero-engine dynamics model, simulation is used to verify the accuracy of this unbalance identification method. The results show that, when the High Pressure rotor has unbalance alone, the vibration reduction rates for the aero-engine rotor system are no less than 93%. For the condition that HP and LP rotors are unbalanced at the same time, using the excitation source separation method proposed in this paper, the balancing effects are also very significant. © 2024, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Nonlinear equations

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Design of 3D-printed Cable Driven Humanoid Hand Based on Bidirectional Elastomeric Passive Transmission

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Chinese Journal of Mechanical Engineering 2021年第4期34卷 225-235页

作者： Teru Chen Xingwei Zhao Guocai Ma Bo Tao Zhouping Yin State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China State Key Laboratory of Intelligent Manufacturing System Technology Beijing Institute of Electronic System EngineeringBeijing 100854China

Motion control of the human hand is the most complex part of the human *** has always been a challenge for a good balance between the cost,weight,responding speed,grasping force,finger extension,and dexterity of prosthetic *** solve these issues,a 3D-printed cable driven humanoid hand based on bidirectional elastomeric passive transmission(BEPT)is designed in this paper.A semi-static model of BEPT is investigated based on energy conservation law to analyze the mechanical properties of BEPT and a dynamical simulation of finger grasping is *** a good imitation of human hand and an excellent grasping performance,specific BEPT is selected according to human finger grasping *** advantage of BEPT based humanoid hand is that a good balance between the price and performance of the humanoid hand is *** proved that the designed prosthetic hand’s single fingertip force can reach 33 N and the fastest fingertip grasping speed realized 0.6 s/180°.It also has a good force compliance effect with only 430g’s *** can not only grab fragile objects like raw eggs and paper cup,but also achieve strong grasping force to damage metal *** humanoid hand has considerable application prospects in artificial prosthesis,human-computer interaction,and robot operation.

关键词： Humanoid hand Bidirectional elastomeric passive transmission Artificial prosthesis

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Investigation on influence of gamma irradiation on piezoelectric and resonance characteristics of surface acoustic wave resonators 5

Investigation on influence of gamma irradiation on piezoelec...

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5th International Conference on Mechanical Engineering and Materials, ICMEM 2024

作者： Sun, Lei Peng, Bin Yang, Yuntao Sun, Zhaofeng Zhu, Jialiang Zhang, Wanli State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of China Chengdu China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

ISBN: (数字)9781510688971

ISBN: (纸本)9781510688964

In this work, an evaluation towards influence of high-dose gamma irradiation on surface acoustic wave (SAW) resonators, is reported. The single-port SAW resonators are fabricated using Lithium niobate (LiNbO3) and Catangasite (CTGS, Ca3TaGa3Si2O14) substrates, along respective cut directions of (0º, 38º, 0º) and (0º, 90º, 0º). Piezoelectric coefficient of substrates, and several main resonance parameters covering resonance frequency, amplitude of resonance peak in reflection coefficient, quality factor together with electromechanical coupling factor of manufactured SAW resonators are investigated, as suitable representatives of piezoelectric and resonance characteristics of SAW resonators. After exposure to gamma ray with a maximum dose of 250 kGy, substrates show insignificant variation not exceeding 6% in their piezoelectric coefficient. Meanwhile, resonance parameters of SAW resonators also alter slightly. Such excellent stability of these characteristics demonstrates credible irradiation hardness owned by both SAW resonators. Results in this study can provide supportive references for usage of LiNbO3 and CTGS-based SAW devices in harsh environments. © 2025 SPIE.

关键词： Gamma rays

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A Cost-Sensitive Multi-scale Feature Multi-order Fusion Network for Bearing Fault Diagnosis Under Data Imbalance Conditions

A Cost-Sensitive Multi-scale Feature Multi-order Fusion Netw...

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International Conference on Artificial Intelligence and Autonomous Transportation, AIAT 2024

作者： Deng, Shuaiqing Lei, Zihao Wen, Guangrui Su, Yu Liu, Zimin Meng, Zhangxuan Zhang, Zhifen National Key Laboratory of Aviation Power System and Plasma Technology Xi’an Jiaotong University Xi’an710049 China State Key Laboratory for Manufacturing Systems Engineering Xi’an Jiaotong University Xi’an710049 China Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System Xi’an Jiaotong University Xi’an710049 China

ISBN: (纸本)9789819639724

Railroad transportation plays a vital role in the national economy, and fault diagnosis of its key components is of great significance in ensuring its safe operation. However, due to its long-term operation in a healthy state, it is tough to obtain fault signals, and this class imbalance data seriously degrades the diagnostic capability of intelligent diagnostic algorithms, leading to increased misclassification of minority classes. To address this problem, we propose a cost-sensitive multi-scale feature multi-order fusion network for bearing fault diagnosis under data imbalance conditions. Firstly, a lightweight multi-scale convolutional layer is employed to effectively extract the multi-scale features of the signal. Then the multi-order feature fusion is performed by a hornet to fully utilize the multi-scale information and enhance the ability to mine the limited diagnostic information of the minority class. And the excellent high-dimensional discriminative features are extracted through residual blocks. In addition, an improved cost-sensitive strategy is designed through the posterior probability distribution to rebalance the contribution of each class to the training process for improving the overall diagnostic performance of the model. Finally, the effectiveness and superiority of the proposed method are comprehensively verified by several sets of experiments with different imbalance rates. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Railroad transportation

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Cavitation recognition of axial piston pumps in noisy environment based on Grad-CAM visualization technique

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CAAI Transactions on Intelligence technology 2023年第1期8卷 206-218页

作者： Qun Chao Xiaoliang Wei Jianfeng Tao Chengliang Liu Yuanhang Wang State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghaiChina State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang UniversityHangzhouChina MoE Key Laboratory of Artificial Intelligence AI InstituteShanghai Jiao Tong UniversityShanghaiChina China Electronic Product Reliability and Environmental Testing Research Institute GuangzhouChina Guangdong Provincial Key Laboratory of Electronic Information Products Reliability Technology GuangzhouChina

The cavitation in axial piston pumps threatens the reliability and safety of the overall hydraulic *** signal can reflect the cavitation conditions in axial piston pumps and it has been combined with machine learning to detect the pump ***,the vibration signal usually contains noise in real working conditions,which raises concerns about accurate recognition of cavitation in noisy *** paper presents an intelligent method to recognise the cavitation in axial piston pumps in noisy ***,we train a convolutional neural network(CNN)using the spectrogram images transformed from raw vibration data under different cavitation ***,we employ the technique of gradient-weighted class activation mapping(Grad-CAM)to visualise class-discriminative regions in the spectrogram ***,we propose a novel image processing method based on Grad-CAM heatmap to automatically remove entrained noise and enhance class features in the spectrogram *** experimental results show that the proposed method greatly improves the diagnostic performance of the CNN model in noisy *** classification accuracy of cavitation conditions increases from 0.50 to 0.89 and from 0.80 to 0.92 at signal-to-noise ratios of 4 and 6 dB,respectively.

关键词： axial piston pump cavitation recognition CNN Grad-CAM spectrogram image

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