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Remaining useful life prediction for train bearing based on an ILSTM network with adaptive hyperparameter optimization

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Transportation Safety and Environment 2024年第2期6卷 75-86页

作者： Deqiang He Jingren Yan Zhenzhen Jin Xueyan Zou Sheng Shan Zaiyu Xiang Jian Miao State key laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures Guangxi Key Laboratory of Manufacturing System&Advanced Manufacturing Tec hnologySc hool of Mec hanical EngineeringGuangxi Univ ersityNanning 530004GuangxiChina Zhuzhou CRRC Times Electric Co. Ltd.Zhuzhou 412001HunanChina

Remaining useful life(RUL)prediction for bearing is a significant part of the maintenance of urban rail transit trains.Bearing RUL is closely linked to the reliability and safety of train running,but the current prediction accuracy makes it difficult to meet the re-quirements of high reliability operation.Aiming at the problem,a prediction model based on an improved long short-term memory(ILSTM)network is proposed.Firstly,the variational mode decomposition is used to process the signal,the intrinsic mode function with stronger representation ability is determined according to energy entropy and the degradation feature data is constructed com-bined with the time domain characteristics.Then,to improve learning ability,a rectified linear unit(ReLU)is applied to activate a fully connected layer lying after the long short-term memory(LSTM)network,and the hidden state outputs of the layer are weighted by attention mechanism.The Harris Hawks optimization algorithm is introduced to adaptively set the hyperparameters to improve the performance of the LSTM.Finally,the ILSTM is applied to predict bearing RUL.Through experimental cases,the better perfor-mance in bearing RUL prediction and the effectiveness of each improving measures of the model are validated,and its superiority of hyperparameters setting is demonstrated.

关键词： train bearing remaining useful life prediction long short-term memory(LSTM) attention mechanism Harris Hawks op-timization(HHO)

Effect of Mn content on microstructure and properties of AlCrCuFeMnx high-entropy alloy

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China Foundry 2024年第2期21卷 147-158页

作者： Ning Wang Kai Ma Qiu-da Li Yu-dong Yuan Yan-chun Zhao Li Feng School of Materials Science and Engineering Lanzhou University of TechnologyLanzhou 730050China State key laboratory of advanced Processing and Reuse of Nonferrous Metals Lanzhou 730050China CNNC Nuclear Power Operation and Management Co. Ltd.Haiyan 314300ZhejiangChina

AlCrCuFeMnx(x=0,0.5,1,1.5,and 2)high-entropy alloys were prepared using the vacuum arc melting technology.The microstructure and mechanical properties of AlCrCuFeMnxwere analyzed and tested by XRD,SEM,TEM,nanoindentation,and electronic universal testing.The results indicate that the AlCrCuFeMnxhigh-entropy alloy exhibits a dendritic structure,consisting of dendrites with a BCC structure,interdendrite regions with an FCC structure,and precipitates with an ordered BCC structure that form within the dendrite.Manganese(Mn)has a strong affinity for dendritic,interdendritic,and precipitate structures,allowing it to easily enter these areas.With an increase in Mn content,the size of the precipitated nanoparticles in the dendritic region initially increases and then decreases.Similarly,the area fraction initially decreases and then increases.Additionally,the alloy’s strength and wear resistance decrease,while its plasticity increases.The Al Cr Cu Fe Mn1.5alloy boasts excellent mechanical properties,including a hardness of 360 HV and a wear rate of 2.4×10^(-5)mm^(3)·N^(-1)·mm^(-1).It also exhibits impressive yield strength,compressive strength,and deformation rates of 960 MPa,1,700 MPa,and 27.5%,respectively.

关键词： high-entropy alloys microstructure mechanical properties wear resistance strengthening mechanisms

Ultracompact silicon on-chip polarization controller

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Photonics Research 2024年第2期12卷 183-193页

作者： WEIKE ZHAO YINGYING PENG MINGYU ZHU RUORAN LIU XIAOLONG HU YAOCHENG SHI DAOXIN DAI State key laboratory for Modern Optical Instrumentation Center for Optical&Electromagnetic ResearchCollege of Optical Science and EngineeringInternational Research Center for Advanced PhotonicsZhejiang UniversityZijingang CampusHangzhou 310058China School of Precision Instrument and Optoelectronic Engineering Tianjin UniversityTianjin 300072China key laboratory of Optoelectronic Information Science and technology Ministry of EducationTianjin 300072China Ningbo Research Institute Zhejiang UniversityNingbo 315100China

On-chip polarization controllers are extremely important for various optical systems.In this paper,a compact and robust silicon-based on-chip polarization controller is proposed and demonstrated by integrating a special polarization converter and phase shifters.The special polarization converter consists of a 1×1 Mach–Zehnder interferometer with two polarization-dependent mode converters at the input/output ends.When light with an arbitrary state of polarization(SOP)is launched into the chip,the TE_(0)and TM_(0)modes are simultaneously excited.The polarization extinction ratio(PER)and the phase difference for the TE_(0)∕TM_(0)modes are tuned by controlling the first phase shifter,the polarization converter,and the second phase shifter.As a result,one can reconstruct the light SOP at the output port.The fabricated polarization controller,as compact as~150μm×700μm,exhibits an excess loss of less than 1 dB and a record PER range of>54 dB for arbitrary input light beams in the wavelength range of 1530–1620 nm.

关键词： polarization SOP interferometer

Reinforced Lewis covalent bond by twinborn nitride heterostructure for lithium-sulfur batteries

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Journal of Energy Chemistry 2024年第1期88卷 363-372,I0009页

作者： Yaochen Song Pengkai Tang Yanjie Wang Yi Wang Linnan Bi Qi Liang Liang He Qingyu Xie Yiyong Zhang Peng Dong Yingjie Zhang Yao Yao Jiaxuan Liao Sizhe Wang Yangtze Delta Region Institute(QuZhou) University of Electronic Science and Technology of ChinaQinzhou 324000ZhejiangChina School of Materials and Energy University of Electronic Science and Technology of ChinaChengdu 611731SichuanChina National and Local Joint Engineering laboratory for Lithium-ion Batteries and Materials Preparation technology Key Laboratory of Advanced Battery Materials of Yunnan ProvinceFaculty of Metallurgical and Energy EngineeringKunming University of Science and TechnologyKunming 650093YunnanChina School of Materials Science and Engineering Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic MaterialsShaanxi University of Science&TechnologyXi’an 710021ShaanxiChina School of Environmental Science and Engineering North China Electric Power UniversityBaoding 071003HebeiChina

The practical application of lithium-sulfur(Li-S)batteries,as promising next-generation batteries,is hindered by their shuttle effect and the slow redox kinetics.Herein,a tungsten and molybdenum nitride heterostructure functionalized with hollow metal-organic framework-derived carbon(W_(2)N/Mo_(2)N)was proposed as the sulfur host.The hollow spherical structure provides storage space for sulfur,enhances electrical conductivity,and inhibits volume expansion.The metal atoms in the nitrides bonded with lithium polysulfides(Li PSs)through Lewis covalent bonds,enhancing the high catalytic activity of the nitrides and effectively reducing the energy barrier of Li PSs redox conversion.Moreover,the high intrinsic conductivity of nitrides and the ability of the heterostructure interface to accelerate electron/ion transport improved the Li+transmission.By leveraging the combined properties of strong adsorption and high catalytic activity,the sulfur host effectively inhibited the shuttle effect and accelerated the redox kinetics of Li PSs.High-efficiency Li+transmission,strong adsorption,and the efficient catalytic conversion activities of Li PSs in the heterostructure were experimentally and theoretically verified.The results indicate that the W_(2)N/Mo_(2)N cathode provides stable,and long-term cycling(over 2000 cycles)at 3 C with a low attenuation rate of 0.0196%per cycle.The design strategy of a twinborn nitride heterostructure thus provides a functionalized solution for advanced Li-S batteries.

关键词： Heterostructure Adsorption Redox kinetics

Constructing electron-blocking grain boundaries in garnet to suppress lithium dendrite growth

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Journal of advanced Ceramics 2024年第2期13卷 166-175页

作者： Xing Xiang Zecheng Fang Congkun Du Zhenzhen Zhao Jiajia Chen Yanhua Zhang Huihu Wang Chenhuinan Wei Fei Chen Qiang Shen Hubei Provincial key laboratory of Green Materials for Light Industry Hubei University of TechnologyWuhan 430068China Hubei Longzhong laboratory Wuhan University of Technology Xiangyang Demonstration ZoneXiangyang 441000China Collaborative Innovation Center of Green Light-weight Materials and Processing Hubei University of TechnologyWuhan 430068China New Materials and Green manufacturing Talent Introduction and Innovation Demonstration Base Hubei University of TechnologyWuhan 430068China State key Lab of advanced technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

Li_(7)La_(3)Zr_(2)O_(12)(LLZO)is considered as a promising solid-state electrolyte due to its high ionic conductivity,wide electrochemical window,and excellent electrochemical stability.However,its application in solid-state lithium metal batteries(SSLMBs)is impeded by the growth of lithium dendrites in LLZO due to some reasons such as its high electronic conductivity.In this study,lithium fluoride(LiF)was introduced into Ta-doped LLZO(LLZTO)to modify its grain boundaries to enhance the performance of SSLMBs.A nanoscale LiF layer was uniformly coated on the LLZTO grains,creating a threedimensional continuous electron-blocking network at the grain boundaries.Benefiting from the electronic insulator LiF and the special structure of the modified LLZTO,the symmetric cells based on LLZO achieved a high critical current density(CCD)of 1.1 mA·cm^(-2)(in capacity-constant mode)and maintained stability over 2000 h at 0.3 mA·cm^(-2).Moreover,the full cells combined with a LiFePO_(4)(LFP)cathode,demonstrated excellent cycling performance,retaining 97.1% of capacity retention after 500 cycles at 0.5 C.Therefore,this work provides a facile and effective approach for preparing a modified electrolyte suitable for high-performance SSLMBs.

关键词： solid electrolyte garnet lithium dendrite microstructure solid-state batteries

Cutting edge preparation of microdrills by shear thickening polishing for improved hole quality in electronic PCBs

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Frontiers of Mechanical Engineering 2024年第2期19卷 99-107页

作者： Jiahuan WANG Mingfeng KE Jiepei LIAO Yu ZHOU Saurav GOEL Jaya VERMA Xu WANG Weigang GUO Julong YUAN Binghai LYU College of Mechanical Engineering Zhejiang University of TechnologyHangzhou 310000China Ultra-precision Machining Center Key Laboratory of Special Purpose Equipment and Advanced Manufacturing TechnologyZhejiang University of TechnologyHangzhou 310000China School of Engineering London South Bank UniversityLondon SE10AAUK Shenzhen Jinzhou Precision technology Corporation Shenzhen 518116China Department of Mechanical Engineering University of Petroleum and Energy StudiesDehradun 248007India Special Equipment Institute Hangzhou Vocational&Technical CollegeHangzhou 310018China

Printed circuit boards(PCBs)are representative composite materials,and their high-quality drilling machining remains a persistent challenge in the industry.The finishing of the cutting edge of a microdrill is crucial to drill performance in machining fine-quality holes with a prolonged tool life.The miniature size involving submicron scale geometric dimensions,a complex flute shape,and low fracture toughness makes the cutting edge of microdrills susceptible to breakage and has been the primary limiting factor in edge preparation for microdrills.In this study,a newly developed cutting edge preparation method for microdrills was tested experimentally on electronic printed circuit boards.The proposed method,namely,shear thickening polishing,limited the cutting edge burrs and chipping on the cutting edge,and this in turn transformed the cutting edge’s radius from being sharp to smooth.Moreover,the edge–edge radius could be regulated by adjusting the processing time.PCB drilling experiments were conducted to investigate the influence of different cutting edge radii on wear,hole position accuracy,nail head value,and hole wall roughness.The proposed approach showed 20%enhancement in hole position accuracy,33%reduction in the nail head value,and 19%reduction in hole wall roughness compared with the original microdrill.However,a threshold is needed;without it,excessive shear thickening polishing will result in a blunt edge,which may accelerate the wear of the microdrill.Wear was identified as the primary factor that reduced hole quality.The study indicates that in printed circuit board machining,microdrills should effectively eliminate grinding defects and maintain the sharpness of the cutting edge as much as possible to obtain excellent drilling quality.Overall,shear thickening polishing is a promising method for cutting edge preparation of microdrills.Further research and optimization can lead to additional improvements in microdrill performance and contribute to the continued advancement of printed circuit board manufa

关键词： microdrill shear thickening polishing cutting edge preparation electronic printed circuit boards hole quality

Multi-layer quasi-zero-stiffness meta-structure for high-efficiency vibration isolation at low frequency

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Applied Mathematics and Mechanics(English Edition) 2024年第7期45卷 1189-1208页

作者： Jiahao ZHOU Jiaxi ZHOU Hongbin PAN Kai WANG Changqi CAI Guilin WEN College of Mechanical and Vehicle Engineering Hunan University State key laboratory of advanced Design and manufacturing for Vehicle Body The Ministry of Science and Technology School of Mechanical Engineering Zhejiang Sci-Tech University School of Mechanical Engineering Yanshan University

An easily stackable multi-layer quasi-zero-stiffness(ML-QZS) meta-structure is proposed to achieve highly efficient vibration isolation performance at low frequency.First, the distributed shape optimization method is used to design the unit cel, i.e., the single-layer QZS(SL-QZS) meta-structure. Second, the stiffness feature of the unit cell is investigated and verified through static experiments. Third, the unit cells are stacked one by one along the direction of vibration isolation, and thus the ML-QZS meta-structure is constructed. Fourth, the dynamic modeling of the ML-QZS vibration isolation metastructure is conducted, and the dynamic responses are obtained from the equations of motion, and verified by finite element(FE) simulations. Finally, a prototype of the ML-QZS vibration isolation meta-structure is fabricated by additive manufacturing, and the vibration isolation performance is evaluated experimentally. The results show that the vibration isolation performance substantially enhances when the number of unit cells increases. More importantly, the ML-QZS meta-structure can be easily extended in the direction of vibration isolation when the unit cells are properly stacked. Hence, the ML-FQZS vibration isolation meta-structure should be a fascinating solution for highly efficient vibration isolation performance at low frequency.

关键词： quasi-zero stiffness (QZS) meta-structure high efficiency low frequency vibration isolation O328 34C15 74P10

Research Progress in the Fabrication of Covalent Organic Framework Membranes for Chemical Separations

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Chinese Journal of Polymer Science 2024年第2期42卷 141-158,I0005页

作者： Cui-Ting Ding Jin-Qiu Yuan Meng-Ying Xie Qing-Yuan Liu Zeng-Guang Yao Shi-Yu Zhang Run-Nan Zhang Hong Wu Zhong-Yi Jiang key laboratory for Green Chemical technology of Ministry of Education School of Chemical Engineering and TechnologyTianjin UniversityTianjin300072China zhejiang Institute of Tianjin University NingboZhejiang315201China Haihe laboratory of Sustainable Chemical Transformations Tianjin300192China Tianjin key laboratory of Membrane Science and Desalination technology Tianjin UniversityTianjin300072China Joint School of National University of Singapore and Tianjin University International Campus of Tianjin UniversityBinhai New CityFuzhou350207China

Membrane technology has become one of the most promising separation technologies for its energy saving, high separation efficiency, environmental friendliness, and economic feasibility. Covalent organic frameworks(COFs) with intrinsically high porosity, controllable pore size, uniform pore size distribution and long-range ordered channel structure, have emerged as next-generation materials to fabricate advanced separation membranes. This feature article summarizes some latest studies in the development of pure COF membranes in our lab, including their fabrication and applications in chemical separations. Finally, current challenges facing high-performance COF separation membranes are discussed.

关键词： Covalent organic frameworks Covalent organic framework membranes Water treatment Organic solvent nanofiltration Gas separation

A 3D-printed microhemispherical shell resonator with electrostatic tuning for a Coriolis vibratory gyroscope

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Microsystems & Nanoengineering 2024年第2期10卷 25-35页

作者： Baoyin Hou Ye Zhu Chaofan He Weidong Wang Zhi Ding Wen He Yong He Lufeng Che College of Information Science and Electronic Engineering Zhejiang UniversityHangzhou310027China Center for Microelectronics Shaoxing InstituteZhejiang UniversityShaoxing312035China State key laboratory of Fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou310058China School of Mechanical Engineering Zhejiang UniversityHangzhou310058China

The emergence of microhemispherical resonant gyroscopes,which integrate the advantages of exceptional stability and long lifetime with miniaturization,has afforded new possibilities for the development of whole-angle gyroscopes.However,existing methods used for manufacturing microhemispherical resonant gyroscopes based on MEMS technology face the primary drawback of intricate and costly processing.Here,we report the design,fabrication,and characterization of the first 3D-printable microhemispherical shell resonator for a Coriolis vibrating gyroscope.We remarkably achieve fabrication in just two steps bypassing the dozen or so steps required in traditional micromachining.By utilizing the intricate shaping capability and ultrahigh precision offered by projection microstereolithography,we fabricate 3D high-aspect-ratio resonant structures and controllable capacitive air gaps,both of which are extremely difficult to obtain via MEMS technology.In addition,the resonance frequency of the fabricated resonators can be tuned by electrostatic forces,and the fabricated resonators exhibit a higher quality factor in air than do typical MEMS microhemispherical resonators.This work demonstrates the feasibility of rapidly batch-manufacturing microhemispherical shell resonators,paving the way for the development of microhemispherical resonator gyroscopes for portable inertial navigation.Moreover,this particular design concept could be further applied to increase uptake of resonator tools in the MEMS community.

关键词： resonator tuning electrostatic