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Prediction of contact resistance of electrical contact wear using different machine learning algorithms

Friction 2024年第6期12卷 1250-1271页

作者： Zhen-bing CAI Chun-lin LI Lei YOU Xu-dong CHEN Li-ping HE Zhong-qing CAO Zhi-nan ZHANG Tribology Research Institute Southwest Jiaotong UniversityChengdu 610031China State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China

H62 brass material is one of the important materials in the process of electrical energy transmission and signal transmission,and has excellent performance in all *** the wear behavior of electrical contact pairs is particularly complex when they are in service,we evaluated the effects of load,sliding velocity,displacement amplitude,current intensity,and surface roughness on the changes in contact *** learning(ML)algorithms were used to predict the electrical contact performance of different factors after wear to determine the correlation between different factors and contact *** forest(RF),support vector regression(SVR)and BP neural network(BPNN)algorithms were used to establish RF,SVR and BPNN models,respectively,and the experimental data were trained and *** was proved that BP neural network model could better predict the stable mean resistance of H62 brass alloy after *** analysis shows that the load and current have great influence on the predicted electrical contact *** wear behavior of electrical contacts is influenced by factors such as load,sliding speed,displacement amplitude,current intensity,and surface roughness during *** learning algorithms can predict the electrical contact performance after wear caused by these *** results indicate that an increase in load,current,and surface roughness leads to a decrease in stable mean resistance,while an increase in displacement amplitude and frequency results in an increase in stable mean resistance,leading to a decline in electrical contact *** reduce testing time and costs and quickly obtain the electrical contact performance of H62 brass alloy after wear caused by different factors,three algorithms(random forest(RF),support vector regression(SVR),and BP neural network(BPNN))were used to train and test experimental results,resulting in a machine learning model suitable for predicting the stable mean

关键词： electrical contact wear contact resistance machine learning(ML) neural network

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Analysis and Suppression of End Flare in AHSS Roll‑Formed Seat Rail

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Automotive Innovation 2023年第3期6卷 404-413页

作者： Tianxia Zou Yang Liu Weiqin Tang Dayong Li State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China

Roll forming has been widely used to manufacture long channels with complex *** flare,one of the typical shape errors,seriously affects the forming accuracy of roll-formed parts,especially using advanced high-strength *** this paper,the mechanism of end flare during the roll forming process of a high-strength automobile seat rail is *** roll forming process of an actual seat rail is *** finite element models of the roll forming process and cut-off springback are established to predict the deformation process and occurrence of end *** results indicate that the uneven distribution of longitudinal and shear residual stress along the length of the part is the main reason for the end *** on the simulation,two strategies are proposed to mitigate the end *** multiple bending processes in the transverse direction effectively balances the longitudinal and shear residual ***,the longitudinal bending process can make the longitudinal residual stress in the roll-formed parts more ***,verification experiments are carried out,and the forming accuracy of the seat rail is significantly improved.

关键词： Seat rail Roll forming End flare Residual stress Geometrical accuracy Finite element modelling

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Construction of mesoporous silica-implanted tungsten oxides for selective acetone gas sensing

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Chinese Chemical Letters 2024年第11期35卷 492-498页

作者： Jichun Li Zhengren Wang Yu Deng Hongxiu Yu Yonghui Deng Xiaowei Cheng Kaiping Yuan Department of Chemistry Shanghai Stomatological Hospital&School of StomatologyState Key Laboratory of Molecular Engineering of PolymersShanghai Key Laboratory of Molecular Catalysis and Innovative MaterialsiCHEMFudan UniversityShanghai 200433China Frontier Institute of Chip and System State Key Laboratory of ASIC and SystemFudan UniversityShanghai 200433China State Key Lab of Transducer Technology Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050China

As a key biomarker for noninvasive diagnosis of diabetes,the selective detection of trace acetone in exhaled gas using a portable and low-cost device remains a great *** metal oxide(SMO)based gas sensors have drawn signification attention due to their potential in miniaturization,user-friendliness,high cost-effectiveness and selective real-time detection for noninvasive clinical ***,we propose a one-pot solvent evaporation induced tricomponent co-assembly strategy to design a novel ordered mesoporous SMO of silica-implanted WO_(3)(Si O_(2)/WO_(3))as sensing materials for trace acetone *** controlled co-assembly of silicon and tungsten precursors and amphiphilic diblock copolymer poly(ethylene oxide)-block-polystyrene(PEO-b-PS),and the subsequent thermal treatment enable the local lattice disorder of WO_(3)induced by the amorphous silica and the formation of ordered mesoporous Si O_(2)/WO_(3)hybrid walls with a unique metastableε-phase WO_(3)*** obtained mesoporous SiO_(2)/WO_(3)composites possess highly crystalline framework with large uniform pore size(12.0-13.3 nm),high surface area(99-113 m^(2)/g)and pore volume(0.17-0.23 cm^(3)/g).Typically,the asfabricated gas sensor based on mesoporous 2.5%Si O_(2)/WO_(3)exhibits rapid response/recovery rate(5/17 s),superior sensitivity(R_(air)/R_(gas)=105 for 50 ppm acetone),as well as high selectivity towards *** limit of detection is as low as 0.25 ppm,which is considerably lower than the thresh value of acetone concentration(>1.1 ppm)in the exhaled breath of diabetic patients,demonstrating its great prospect in real-time monitoring in diabetes ***,the mesoporous 2.5%Si O_(2)/WO_(3)sensor is integrated into a wireless sensing module connected to a smart phone,providing a convenient real-time detection of acetone.

关键词： Mesoporous materials ε-Tungsten oxide Silica-implanted Acetone sensing Real-time detection

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Effects of fluorene-9-bisphenol exposure on anxiety-like and social behavior in mice and protective potential of exogenous melatonin

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Environmental Science and Pollution Research 2024年第20期31卷 29385-29399页

作者： Zuo, Xiang Zhang, Shuhui Bai, Huijuan Yu, Qian Zhao, Qili Sun, Mingzhu Zhao, Xin Feng, Xizeng College of Life Sciences State Key Laboratory of Medicinal Chemical Biology Key Laboratory of Bioactive Materials Ministry of Education Nankai University Weijin Road 94 Tianjin300071 China Institute of Robotics & amp Automatic Information System College of Artificial Intelligence Nankai University Tianjin300071 China

Fluorene-9-bisphenol (BHPF) is widely used in the manufacture of plastic products and potentially disrupts several physiological processes, but its biological effects on social behavior remain unknown. In this study, we investigated the effects of BHPF exposure on anxiety-like and social behavior in female mice and the potential mechanisms, thereby proposing a potential therapy strategy. We exposed female Balb/c mice to BHPF by oral gavage at different doses (0.5, 50 mg/kg bw/2-day) for 28 days, which were found BHPF (50 mg/kg) exposure affected motor activity in the open field test (OFT) and elevated cross maze (EPM), resulting in anxiety-like behaviors, as well as abnormal social behavioral deficits in the Social Interaction Test (SIT). Analysis of histopathological staining results showed that BHPF exposure caused damage to hippocampal neurons in the CA1/CA3/DG region and decreased Nissl pyramidal neurons in the CA1/CA3 regions of the hippocampus, as well as a decrease in parvalbumin neuron expression. In addition, BHPF exposure upregulated the expression of excitatory and inhibitory (E/I) vesicle transporter genes (Vglut1, Vglut2, VGAT, GAD67, Gabra) and axon growth gene (Dcc) in the mouse hippocampus. Interestingly, behavioral disturbances and E/I balance could be alleviated by exogenous melatonin (15 mg/kg bw/2-day) therapy. Our findings suggest that exogenous melatonin may be a potential therapy with protective potential for ameliorating or preventing BHPF-induced hippocampal neuronal damage and behavioral disturbances. This study provided new insight into the neurotoxicological effects on organisms exposed to endocrine-disrupting chemicals and aroused our vigilance in current environmental safety about chemical use. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.

关键词： Neurons

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Mechanical Properties Inside Origami-Inspired Structures: An Overview

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Applied Mechanics Reviews 2025年第1期77卷 011001页

作者： Yan, Peng Huang, Hailin Meloni, Marco Li, Bing Cai, Jianguo Department of Mechanical Engineering and Automation Harbin Institute of Technology Shenzhen518052 China Harbin Institute of Technology Shenzhen518052 China Key Laboratory of C & PC Structures of Ministry of Education National Prestress Engineering Research Center Southeast University Nanjing211189 China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China Guangdong Provincial Key Laboratory of Intelligent Morphing Mechanisms and Adaptive Robotics Harbin Institute of Technology Shenzhen518052 China Key University Laboratory of Mechanism Machine Theory and Intelligent Unmanned Systems of Guangdong Habin Institute of Technology Shenzhen518052 China

In recent decades, origami has transitioned from a traditional art form into a systematic field of scientific inquiry, characterized by attributes such as high foldability, lightweight frameworks, diverse deformation modes, and limited degrees-of-freedom. Despite the abundant literature on smart materials, actuation methods, design principles, and manufacturing techniques, comprehensive reviews focusing on the mechanical properties of origami-inspired structures are relatively rare and unsystematic. This review aims to fill this void by analyzing and summarizing the significant studies conducted on the mechanical properties of origami-inspired structures from 2013 to 2023. We begin with an overview that includes essential definitions of origami, classical origami patterns, and their associated tessellated or stacked structures. Following this, we delve into the principal dynamic modeling method for origami and conduct an in-depth analysis of the key mechanical properties of origami-inspired structures. These properties include tunable stiffness, bistability and multistability, metamechanical properties demonstrated by origami-based metamaterials, and bio-inspired mechanical properties. Finally, we conclude with a comprehensive summary that discusses the current challenges and future directions in the field of origami-inspired structures. Our review provides a thorough synthesis of both the mechanical properties and practical applications of origami-inspired structures, aiming to serve as a reference and stimulate further research. © 2025 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Degrees of freedom (mechanics)

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Microscopic Protection Mechanisms of Antioxidants on Vegetable Oils at Different Moisture Levels Based on Quantum Mechanics and Reactive Molecular Dynamic Simulations

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IEEE Transactions on Dielectrics and Electrical Insulation 2025年第3期32卷 1252-1262页

作者： Hu, Xuefeng Cong, Haoxi Quan, Shaomin Su, Wenjing Wang, Yuxin Liu, Zhaoling Xie, Li Cheng, Yangchun Li, Qingmin North China Electric Power University State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources Beijing102206 China

New transformers using vegetable oil as the insulating liquid have promising applications, but the oxidative stability of vegetable oil limits its development. Currently, an effective improvement method is adding antioxidants. In this paper, simulations based on quantum mechanics and reactive molecular dynamics are used to study the molecular properties of different antioxidants and their protective effect on vegetable oil at different moisture levels. The results showed that propyl gallate (PG) has a higher molecular polarity index (MPI) and more molecular polar surface area than tert-butyl hydroquinone (TBHQ) and butyl hydroxytoluene (BHT). As a result, PG has a higher polarity and is able to create more hydrogen bonds with water and triglycerides. Due to the smaller molecular orbital gap of PG, it is easier to protect against the molecular degradation of vegetable oils. PG has higher antioxidant activity than TBHQ and BHT. However, PG is hydrophilic and will be affected at high moisture levels and its antioxidant performance will be reduced. The above research reveals the molecular characteristics of antioxidants at the microscopic level and proposes the influence laws of antioxidants on vegetable oils. It provides theoretical support for the application of vegetable oil in large-scale oil-immersed transformers. © 1994-2012 IEEE.

关键词： Hydrogen bonds

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Fabrication of amorphous nanoporous ZrO_(2)/SiO_(2) aerogel enabling nonlinear optical properties

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Journal of Materiomics 2024年第5期10卷 1109-1116页

作者： Hongwei Chu Mingjie Xu Benxue Liu Zhongben Pan Han Pan Shengzhi Zhao Dong Xu Dechun Li School of Information Science and Engineering and Key Laboratory of Laser and Infrared System of Ministry of EducationShandong UniversityQingdao266237ShandongChina State Key Laboratory of Crystal Materials Shandong UniversityJinan250100China

Amorphous oxides have unique physicochemical properties with extensive opto-electronic applications such as the thin-film transistor,light-emitting diode backplanes,and supercontinuum *** this contribution,we synthesize the amorphous ZrO_(2)/SiO_(2) nanoporous aerogel with high structural *** the femtosecond excitation laser at 800–1,064 nm,the broadband second harmonic generation is *** nonlinear optical properties of the as-prepared ZrO_(2)/SiO_(2) aerogel are investigated at 1.0μm and 1.5μm for the first ***,the amorphous ZrO_(2)/SiO_(2) saturable absorber is originally applied in the Yb-doped and Er-doped fiber lasers to realize the mode-locking *** the Yb-doped fiber laser,the dissipative soliton resonance mode-locking operation is demonstrated with the largest pulse duration of 22 ns at a repetition rate of 7.8 MHz and a high signal-to-noise ratio of 64 *** the Er-doped fiber laser,a conventional soliton mod-locking regime is observed with an ultrashort pulse width of 960 fs,a repetition frequency of 6.55 MHz,and a time-bandwidth production of *** work shows the good ability of the ZrO_(2)/SiO_(2) aerogel in generating ultrafast pulses and extends the saturable absorber into the amorphous material realm.

关键词： ZrO_(2)/SiO_(2)aerogel Nonlinear optical properties Second harmonic generation Dissipative soliton resonance Soliton mode-locking

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Interactions between Initial and Lateral Boundary Perturbations in Convection-Permitting Ensemble Prediction

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Journal of Meteorological Research 2025年第1期39卷 116-131页

作者： Jingzhuo WANG Jing CHEN Fajing CHEN Yanan Ma CMA Earth System Modeling and Prediction Centre China Meteorological Administration(CMA)Beijing100081China State Key Laboratory of Severe Weather China Meteorological AdministrationBeijing100081China Key Laboratory of Earth System Modeling and Prediction China Meteorological AdministrationBeijing100081China Chinese Academy of Meteorological Sciences China Meteorological AdministrationBeijing100081China

How to construct appropriate perturbations for convection-permitting ensemble prediction systems(CPEPSs)is a critical issue awaiting urgent *** two common perturbations,initial perturbations(IPs)and lateral boundary perturbations(BPs)interact with each other,affecting the model error growth,especially in mesoscale *** the china Meteorological Administration(CMA)-CPEPS,this study tries to elucidate how BPs interact with matched and mismatched IPs under varied large-scale weather conditions/*** groups of experiments were conducted for strong-forcing and weak-forcing weather regimes over southern china:three with single IPs,one with single BPs,and three with combined *** is found that the perturbation magnitudes were dominated by meso-α-scale components,and IPs under weak forcing exhibited more pronounced effects than under strong forcing;whereas BPs exerted more pronounced effects under strong forcing than weak forcing ***,it lasts longer for high-level variables when the perturbation energy from BPs is higher than that from IPs,compared to low-level ***,for precipitation and dynamic variables,IPs and BPs can mutually *** source of these perturbations,and their specific vertical levels,do not alter the extent of their ***,the weather regime and the scales of the perturbations influence the strength of their mutual *** particular,the weak-forcing regimes exhibit a more pronounced reinforcing effect,and meso-α-scale perturbations are more conducive to fostering interactions compared to meso-β-scale ***,it is the perturbation magnitude inherent in the initial perturbation itself that determines the interactions between IPs and BPs.

关键词： interactions initial perturbations lateral boundary perturbations convection-permitting ensemble prediction

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Magnetic Actuated Shape-memory Helical Microswimmers with Programmable Recovery Behaviors

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Journal of Bionic Engineering 2021年第4期18卷 799-811页

作者： Fu Zhao Weibin Rong Lefeng Wang Lining Sun State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin150080China

Inspired by bacterial flagella in nature,magnetic helical microswimmer is an ideal model to perform complex task in a low Reynolds number *** Memory Polymers(SMPs)with desirable properties are considered as one of the most preferred options for the development of small-scale ***,fabricating and programming strategies are still ***,we report an approach to fabricate helical microswimmers based on thermoplastic SMP(polylactic acid).Melt-spun polylactic acid fibers containing magnetic particles were enwound to form helical *** shape recovery behaviors were programmed by annealing and *** forms of helical microswimmers(constant-helix-angle conical helix,constant-pitch conical helix,and straight helix)with controlled morphological parameters were *** obtained microswimmers showed 3D locomotion capability under rotating magnetic *** maximum swimming velocity of microswimmers was nearly six body lengths per second,and the near-wall swimming of conical helixes along their sharp end exhibited a smaller ***,we demonstrated programmed shape-switching processes(spring-like contraction and elongation,coiling and uncoiling)and self-repairing of the *** demonstrations of potential applications,tasks of mobile microstent,cargo delivery,and minimally invasive injection were carried *** multifunctional shape-memory microswimmers have immense potential in a variety of applications.

关键词： helical microrobot magnetic actuation Shape Memory Polymer(SMP) polylactic acid magnetic particles

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Fabrication of a biomimetic controllable adhesive surface by ultraprecision multistep and layered scribing and casting molding

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Science china(Technological Sciences) 2021年第8期64卷 1814-1826页

作者： WANG Wei XIE ZongWu State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin150001China

Wedge-shaped microstructures have the ability to reproduce the excellent adhesive properties of geckos’feet because of their unique anisotropic *** particular,the controllability of the wedge-shaped microstructures on adhesion is beneficial to the undisturbed grasp or the capture of space ***,the problem currently remains of how to process it efficiently and with high *** a strategy called ultraprecision multistep and layered scribing is proposed for the manufacture of the biomimetic controllable adhesive *** results show that the metal master mold prepared based on the manufacturing strategy has not only good surface topography but also high reliability and ***,the controllable adhesive surface of 1.96 cm2,fabricated by the proposed manufacturing strategy,has a normal adhesion of 1.012 N,and the corresponding shear friction and adhesion coefficient are 3.105 N and 4.82,***,the controllable adhesive surface has been shown to be approximately superhydrophobic and also to possess the properties of controllable adhesion and dynamic ***,after 250 adhesion-detachment cycles,the normal adhesion and shear friction only decrease by 5%and 3%,*** research realizes an environmentally friendly and efficient method by which to manufacture a durable metal mold for fabricating a biomimetic controllable adhesive surface,laying a foundation for its effective application in the adherence of space-floating targets.

关键词： continuous and tilted wedge-shaped microstructures biomimetic controllable adhesive surface ultraprecision multistep and layered scribing controllable adhesion dynamic adhesion

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