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Tribological properties of PTFE-based fabric composites at cryogenic temperature

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Friction 2024年第2期12卷 245-257页

作者： Mingkun XU Zidan wang Lihe guo Liming TAO Tianbao MA Tingmei wang Qihua wang Key Laboratory of Science and Technology on Wear and Protection of Materials Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

Fabric composites are widely employed in self-lubricating bearing liners as solid lubrication *** the tribological behaviors of fabric composites have been extensively studied,the cryogenic tribological properties and mechanisms have been scarcely reported and are largely unclear to instruct material design for aerospace and other high-tech ***,the tribological properties of polytetrafluoroethylene(PTFE)-based hybrid-fabric composites were investigated at cryogenic and ambient temperatures in the form of pin-on-disk friction under heavy *** results suggest that the friction coefficients of the hybrid-fabric composites obviously increase with a decrease in wear when the temperature drops from 25 to−150°***,thermoplastic polyetherimide(PEI),as an adhesive for fabric composites,has better cryogenic lubrication performance than thermosetting phenol formaldehyde(PF)resin,which can be attributed to the flexible chemical structure of *** excellent lubrication performance of hybrid-fabric composites is attributed to the transfer film formed by PTFE fibers on the surface of fabrics.

关键词： cryogenic temperatures fabric composites friction and wear transfer film

Cushioning Performance of a Novel Polyurethane Foam Material Applied in Fragile Packaging

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Acta Mechanica Solida Sinica 2024年第3期37卷 487-497页

作者： Huifeng Xi Chunqiu guo Jinbiao Yang Xiaogang wang Bowei wang Shiqing Huang Zhiwei wang School of Mechanics and Construction Engineering Jinan UniversityGuangzhou510632China College of Packing Engineering Jinan UniversityZhuhai519070China MOE Key Lab of Disaster Forecast and Control in Engineering Jinan UniversityGuangzhou510632China Foshan Soft Valley Technology Co. Ltd.Foshan528000China

For fragile products,packaging requires cushioning protection to prevent irreversible damage from accidental falls,transportation impacts,and other *** new polyurethane foam(PUF)material demonstrates superior cushioning and vibration isolation performance in practical applications,effectively minimizing damage from *** and vibration experiments were conducted on packages comprising novel PUF,expandable polyethylene,ethylene-vinyl acetate copolymer foam,and *** verify that the new PUF material outperforms in cushioning and vibration isolation,as observed from the acceleration ***,a random vibration analysis of a packaging unit involving different thicknesses of PUF materials and bracelets reveals the enhanced vibration isolation effect within a specific thickness *** vibration results of the bracelet’s outer packaging align closely with finite element simulation results,validating the effectiveness of designing and optimizing the outer *** finite element simulation,deeper understanding and prediction of the bracelet’s vibration response under various conditions is achieved,facilitating optimized packaging design for better protection and vibration damping.

关键词： Flexible polyurethane foam Packaging of fragile goods Nonlinear dynamics Vibration frequency Finite element simulation

Machine learning model based on non-convex penalized huberized-SVM

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Journal of Electronic Science and Technology 2024年第1期22卷 81-94页

作者： Peng wang Ji guo Lin-Feng Li School of Finance and Economics Xizang Minzu UniversityXianyang712082China Research Center for Quality Development of Xizang Special Industries Xianyang712082China School of Computer Science and Technology Xinjiang UniversityUrumqi830017China

The support vector machine(SVM)is a classical machine learning *** the hinge loss and least absolute shrinkage and selection operator(LASSO)penalty are usually used in traditional ***,the hinge loss is not differentiable,and the LASSO penalty does not have the Oracle *** this paper,the huberized loss is combined with non-convex penalties to obtain a model that has the advantages of both the computational simplicity and the Oracle property,contributing to higher accuracy than traditional *** is experimentally demonstrated that the two non-convex huberized-SVM methods,smoothly clipped absolute deviation huberized-SVM(SCAD-HSVM)and minimax concave penalty huberized-SVM(MCP-HSVM),outperform the traditional SVM method in terms of the prediction accuracy and classifier *** are also superior in terms of variable selection,especially when there is a high linear correlation between the *** they are applied to the prediction of listed companies,the variables that can affect and predict financial distress are accurately filtered *** all the indicators,the indicators per share have the greatest influence while those of solvency have the weakest *** companies can assess the financial situation with the indicators screened by our algorithm and make an early warning of their possible financial distress in advance with higher precision.

关键词： Huberized loss Machine learning Non-convex penalties Support vector machine(SVM)

Vibration response and safety control for blasting vibration of the existing tunnel with defects

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Underground Space 2024年第2期15卷 76-89页

作者： Junying Xia Bo wang Xinxin guo Zhuoxiong Xie Key Laboratory of Transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China College of Environment and Civil Engineering Chengdu University of TechnologyChengdu 610059China Guangdong Communication Planning&Design Institute Group Co. LtdGuangzhou 510507China

Current studies on blasting construction of small clear-distance tunnels have not considered the impact of existing tunnel lining defects when establishing safety *** paper offers a series of study results based on the blasting project of a new tunnel adjacent to the existing defect Xinling tunnel to thoroughly examine the dynamic response,safety control standards,and measures of the existing defect ***,structural models were developed to investigate the influence of the presence or absence of specific defects(like lining cracks and cavities behind the lining)on the dynamic response of the current tunnel lining to identify the most unfavorable defect ***,establish safety control standards for intact linings and those with the most unfavorable ***,two types of control measures,single safe charge and reasonable delay time,were studied based on the established safety control *** particular,the most adverse position of cracks was the wall facing the explosion,the rise in depth was more unfavorable for vibration response,and the impact of the longitudinal crack was restricted to the vicinity of the *** the vault was the most adverse cavity position,the rise in cavity area was more damaging,and the influence range varied with longitudinal cavity ***,the impact of cracks was mainly evident in the amplification effect of stress at the crack *** contrast,cavities had varied degrees of amplification effects on the vibration velocity and stress response and a relatively extensive influence *** control research was conducted,when the tunnel was intact,with a right wall crack,a vault cavity,and both vault cavity and crack for this project,the peak particle velocity(PPV)of the safety control standard for vibration velocity was 13,10,13,and 8 cm/s,respectively,and the respective single safe charge could be adjusted at 64,53,37,and 25 ***,the presence of different defects had a relati

关键词： Existing tunnel Defect Blasting construction Vibration response Control standards and measures

Generation and characterization of customized Laguerre–Gaussian beams with arbitrary profiles

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Frontiers of physics 2024年第4期19卷 235-241页

作者： Chengyuan wang yun Chen Jinwen wang Xin Yang Hong Gao Fuli Li Ministry of Education Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter Shaanxi Province Key Laboratory of Quantum Information and Quantum Optoelectronic DevicesSchool of PhysicsXi’an Jiaotong UniversityXi’an 710049China Department of Physics Huzhou UniversityHuzhou 313000China

We experimentally demonstrate the generation of customized Laguerre–Gaussian(LG)beams whose intensity maxima are localized around any desired *** principle is to act with appropriate algebraic functions on the angular spectra of LG *** characterize the propagation properties of these beams and compare them with non-diffraction caustic beams possessing the same intensity *** results manifest that the customized-LG beams can maintain their profiles during propagation and suffer less energy loss than the non-diffraction caustic beams,and hence are able to propagate a longer ***,the customized-LG beam exhibits self-healing ability when parts of their bodies are *** new structure beam has potential applications in areas such as optical communication,soliton routing and steering,and optical tweezing.

关键词： light manipulation wave propagation invariant optical fields

Parameter calibration of the tensile-shear interactive damage constitutive model for sandstone failure

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1153-1174页

作者： yun Shu Zheming Zhu Meng wang Weiting Gao Fei wang Duanying Wan yuntao wang MOE Key Laboratory of Deep Earth Science and Engineering College of Architecture and EnvironmentSichuan UniversityChengdu610065China Failure Mechanics and Engineering Disaster Prevention Key Laboratory of Sichuan ProvinceSichuan UniversityChengdu610065China Tianfu Engineering-oriented Numerical Simulation & Software Innovation Center Chengdu620107China

The tensile-shear interactive damage(TSID)model is a novel and powerful constitutive model for rock-like *** study proposes a methodology to calibrate the TSID model parameters to simulate *** basic parameters of sandstone are determined through a series of static and dynamic tests,including uniaxial compression,Brazilian disc,triaxial compression under varying confining pressures,hydrostatic compression,and dynamic compression and tensile tests with a split Hopkinson pressure *** on the sandstone test results from this study and previous research,a step-by-step procedure for parameter calibration is outlined,which accounts for the categories of the strength surface,equation of state(EOS),strain rate effect,and *** calibrated parameters are verified through numerical tests that correspond to the experimental loading *** between numerical results and experimental data indicates the precision and reliability of the calibrated *** methodology presented in this study is scientifically sound,straightforward,and essential for improving the TSID ***,it has the potential to contribute to other rock constitutive models,particularly new user-defined models.

关键词： Damage constitutive model Parameter calibration Rock modeling Sandstone Dynamic impact load Tensile-shear interactive damage(TSID)model

Adaptive patient-cooperative compliant control of lower limb rehabilitation robot

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Biomimetic Intelligence & Robotics 2024年第2期4卷 42-49页

作者： Lingling Chen Jjiabao Huang Yanglong wang Shijie guo Mengge wang Xin guo School of Artificial Intelligence Hebei University of TechnologyTianjin 300400China Inteligent Rehabilitation Device and Detection Technology Engineering Research Centre of the Ministry of Education Tianjin 300400China School of Mechanical Engineering Hebei University of TechnologyTianjin 300400China School of Electrical Engineering Hebei University of TechnologyTianjin 300400China

With the increase in the number of stroke patients,there is a growing demand for rehabilitation ***-assisted training is expected to play a crucial role in meeting this *** ensure the safety and comfort of patients during rehabilitation training,it is important to have a patient-cooperative compliant control system for rehabilitation *** order to enhance the motion compliance of patients during rehabilitation training,a hierarchical adaptive patient-cooperative compliant control strategy that includes patient-passive exercise and patient-cooperative exercise is proposed.A low-level adaptive backstepping position controller is selected to ensure accurate tracking of the desired *** the high-level,an adaptive admittance controller is employed to plan the desired trajectory based on the interaction force between the patient and the *** results of the patient-robot cooperation experiment on a rehabilitation robot show a significant improvement in tracking trajectory,with a decrease of 76.45%in the dimensionless squared jerk(DSJ)and a decrease of 15.38%in the normalized root mean square deviation(NRMSD)when using the adaptive admittance *** proposed adaptive patient-cooperative control strategy effectively enhances the compliance of robot movements,thereby ensuring the safety and comfort of patients during rehabilitation training.

关键词： Compliant control Lower limb rehabilitation robot(LLRR) Adaptive admittance controller Adaptive backstepping controller Human-robot interaction

Mechanism of a dual-phase Ti-Nb alloy exhibiting near-linear elastic deformation

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Rare Metals 2024年第5期43卷 2282-2289页

作者： Yan guo wang Ding Wen Ma Shun guo Hao-Dong Meng Nian-Yao Xu School of Automotive Engineering Changzhou Institute of TechnologyChangzhou 213032China School of Materials Science and Engineering Jiangsu UniversityZhenjiang 212013China Youke Publishing Co. LtdChina Grinm Group Co.LtdBeijing 100088China

In this work,the underlying mechanism responsible for the near-linear elastic deformation behavior of a dual-phase Ti-Nb alloy consisting of β and α'' phase with large recoverable strain was systematically *** on in situ synchrotron X-ray diffraction(SXRD)analyses,it was found that besides intrinsic elastic deformation,a slight reversible β-α'' stress-induced martensitic(SIM)transformation,which proceeded in a consecutive mode under the retarding effect of micro-defects,took place during the near-linear elastic *** unloading,a small amount of residual macroscopic strain remained in the specimen due to the incomplete reverse α''→β transformation on *** high near-linear elastic deformability of the cold drawing(CD)Ti-Nb alloy has been revealed to be attributed to the coupling actions of intrinsic elasticity as well as the consecutive and reversible β-α'' SIM *** research may contribute to a new avenue for the design and development of novel dual-phase Ti-based alloys with desirable elastic deformability.

关键词： Titanium alloys Dual-phase Near-linear elastic deformation Martensitictransformation

Lead-free piezoceramic macro-fiber composite actuators toward active vibration control systems

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Journal of Materiomics 2024年第1期10卷 78-85页

作者： Binquan wang Geng Huangfu Jie wang Shujun Zhang Yiping guo State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai200240China Institute for Superconducting and Electronic Materials Australian Institute for Innovative MaterialsUniversity of WollongongWollongongNSW2500Australia

Macro-fiber composite actuators(MFCAs)suffer from strict restrictions on the utilization of lead-containing precursors due to growing environmental *** address this issue,a novel lead-free MFCA based on potassium sodium niobate piezoceramics has been developed using the dice&fill *** MFCA demonstrates large electric field-induced displacement(31.4μm over-500-1500 V at 0.5 Hz),excellent frequency stability,and a strong linear relationship between the induced displacement and the external voltage ***,unlike lead-based MFCA that requires superposition of a negative dc bias voltage to pursue higher output performance but risks depolarization,lead-free MFCA can achieve larger displacement by superimposing only a positive bias *** device exhibits excellent reliability,maintaining a stable output over 10^(5) electrical ***,a“back-to-back”coupled MFCA has been developed to regulate bidirectional displacement,making it suitable for various practical applications,including active vibration *** approach has resulted in a 90%vibration reduction and provides new insights into the design of MFCAs,further facilitating their application in active vibration control systems.

关键词： Lead-free piezoceramic actuator Macro-fiber composite Active vibration control