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Modelling and experimental investigation of micro-dimpled structures milling with spiral trajectory tool reciprocating motion

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Chinese Journal of Aeronautics 2025年第2期38卷 577-596页

作者： Guangzhou WANG Linjie ZHAO Qi LIU Xiguang LI Yazhou SUN Mingjun CHEN School of Mechatronics Engineering Harbin Institute of TechnologyHarbin 150001China Centre for Precision Manufacturing DMEMUniversity of StrathclydeGlasgow G11XJUK State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China

To mill fine and well-defined micro-dimpled structures,a machining manner of spiral trajectory tool reciprocating motion,where the tool repeats the process of‘feed milling–retract–cutting feed–feed milling again’along the spiral trajectory,was *** the kinematics analysis,it is found that the machining quality of micro-dimpled structures is highly dependent on the machining trajectory using spiral trajectory tool reciprocating *** reveal this causation,simulation modelling and experimental studies were carried out.A simulation model was developed to quantitatively and qualitatively investigate the influence of the trajectory discretization strategies(constant-angle and constant-arc length)and parameters(discrete angle,discrete arc length,and pitch)on surface texture and residual height of micro-dimpled ***,micro-dimpled structures were milled under different trajectory discretization strategies and parameters with spiral trajectory tool reciprocating motion.A comprehensive comparison between the milled results and simulation analysis was made based on geometry accuracy,surface morphology and surface roughness of milled ***,the errors and factors affecting the above three aspects were *** results demonstrate both the feasibility of the established simulation model and the machining capability of this machining way in milling high-quality micro-dimpled *** trajectory tool reciprocating motion provides a new machining way for milling micro-dimpled structures and micro-dimpled functional *** an appropriate machining trajectory can be generated based on the optimized trajectory parameters,thus contributing to the improvement of machining quality and efficiency.

关键词： Tool reciprocating motion Spiral trajectory Micro-dimpled structure Micromachining Simulation modelling with diamond tool Surface texture

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Radiation belt electron wisp inside South Atlantic Anomaly due to terrestrial VLF transmitter observed by MSS-1

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Science China Earth Sciences 2025年第2期68卷 538-548页

作者： Yixin SUN Ying LIU Qiugang ZONG Yixin HAO Hong ZOU Yuguang YE Institute of Space Physics and Applied Technology Peking UniversityBeijing 100871China State Key Laboratory of Lunar and Planetary Science Macao University of Science and TechnologyMacao 999078China Max Planck Institute for Solar System Research Goettingen 37077Germany

The South Atlantic Anomaly represents a region within near-Earth space characterized by a significantly weaker geomagnetic field and a higher flux of energetic particles compared to other areas. It is a space weather hazards to Low-EarthOrbit satellites. There has been evidence that the Very Low Frequency(VLF) waves from the powerful ground VLF radio transmitter in Australia, known as NWC, have the capacity to scatter energetic electrons' pitch angle in the inner radiation *** scattering directs electrons into the drift loss cone, forms a “wisp”, characterized by its peak intensity outside the South Atlantic Anomaly(SAA), and a “rift” exhibiting minimal intensity within SAA. Our findings mark the initial observation of a“wisp” precipitation, an unusual occurrence with peak intensity detected inside the SAA, observed via the Macao Science Satellite-1. Enabled by the Medium-energy Electron Spectrometer onboard Macao Science Satellite-1, we were able to comprehensively measure the full pitch angle distribution at Low-Earth-Orbit. This allowed us to attribute the “wisp” within the anomaly to a specific pitch angle range just outside the drift loss cone, a measurement unattainable by previous satellites. This“wisp” occurrence aligns with previous model predictions, despite being overlooked. Moreover, we distinguished between the trapped and precipitating electron populations. Directly derived from the ratio of these populations, our analysis revealed that approximately 2%-5% of trapped electrons will be lost in this specific wisp due to the influence of the ground VLF *** results not only complement existing evidence of energetic electron pitch angle scattering facilitated by the ground VLF transmitter but also offer a quantitative estimation of its impact.

关键词： South Atlantic Anomaly Radiation belts Electrons precipitation VLF transmitter Wave-particle interaction

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An Optimal Control Based Trajectory Planning Method for Cooperative Merging Maneuvers 3

An Optimal Control Based Trajectory Planning Method for Coop...

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3rd International Symposium on intelligent Robotics and systems, ISoIRS 2023

作者： Wang, Qi Ge, Hao Duan, Xuting Zhou, Jianshan School of Transportation Science and Engineering Beihang University State Key Lab of Intelligent Transportation System Beijing Key Laboratory for Cooperative Vehicle Infrastructure Systems and Safety Control State Key Laboratory of Air Traffic Management System and Technology Beijing China Nanjing Research Institute of Electronic Engineering State Key Laboratory of Air Traffic Management System and Technology Nanjing China School of Transportation Science and Engineering Beihang University State Key Lab of Intelligent Transportation System Beijing Key Laboratory for Cooperative Vehicle Infrastructure Systems and Safety Control Beijing China

ISBN: (纸本)9798350339963

Due to the prediction errors and diverse driving styles of surrounding vehicles, traffic congestion and even accidents can occur in the traffic bottleneck area where vehicles merge into the main road. To ensure that connected and automated vehicles (CAVs) can quickly and efficiently merge into the main road, this paper proposes a cooperative trajectory planning method based on optimal control for vehicle cut-in scenarios. A optimal control model is constructed, and a quintic polynomial is used to generate the initial solution of the optimal control problem to accelerate the solution process and improve the success rate. Finally, The obtained merging trajectory is then synchronized with the movement of vehicles on the main road to optimize their actions and ensure a safe merging process. Joint simulation with Robot Operating system (ROS) and RVIZ is utilized, and the results show that the proposed algorithm can quickly obtain cooperative results, the locally successful merging trajectory meets the requirements of smoothness and safety, and if the solution does not allow merging, the merging vehicle is instructed to terminate the execution. © 2023 IEEE.

关键词： Trajectories

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Linear Modulation of the Resonant Frequency of a Double-bubble Model Below an Air-Water Interface

Linear Modulation of the Resonant Frequency of a Double-bubb...

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2024 OES China Ocean Acoustics, COA 2024

作者： Cheng, Xuan Li, Shiyu Gong, Zhixiong Fan, Jun School of Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai China School of Ocean and Civil Engineering Shanghai Jiao Tong University State Key Laboratory of Ocean Engineering Key Laboratory of Marine Intelligent Equipment and System Shanghai China School of Ocean and Civil Engineering Key Laboratory of Marine Intelligent Equipment and System State Key Laboratory of Ocean Engineering Shanghai China

ISBN: (纸本)9798350340297

The study of sound wave propagation across the air-water interface is important for several potential applications, e.g., acoustic communication between underwater environments and air. However, only 0.1% of the power of the incident wave perpendicular to the interface can cross the interface owing to the large acoustic-impedance mismatch between air and water. This renders the propagation of acoustic energy between the media inefficient, leading to the failure of effective acoustic communication between these media. This situation could be solved using designed bubble systems because bubbles are good acoustic impedance matchers. The existing research is mainly limited periodic single-bubble systems, which are not suitable for acoustic propagation in the broadband frequency range. This is because the large sound transmission coefficient between the air-water interface occurs only near a sharp resonant frequency and decreases rapidly away from the resonance. In this work, we propose a periodic double-bubble model below the air-water interface for efficient propagation over a wide frequency range. A numerical simulation model based on COMSOL was developed and validated through comparison with a theoretically analyzed periodic single-bubble system. Then, a periodic double- bubble model was built to study the modulation effect of the resonance frequency versus the vertical interval between the two bubbles. Numerical simulations show that the resonant frequency of the periodic double-bubble system varies linearly with the vertical interval. Therefore this study offers a potential method for designing broadband acoustic communication techniques across the sea-air interface. © 2024 IEEE.

关键词： Acoustic impedance

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Effect of Free-End Torsion on the Corrosion and Mechanical Properties for Mg-3Zn-0.2Ca Alloy

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Acta Metallurgica Sinica(English Letters) 2025年第1期38卷 59-70页

作者： Li-Lan Gao Jiang Ma Yan-Song Tan Xiao-Hao Sun Qi-Jun Gao De-Bao Liu Chun-Qiu Zhang Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical EngineeringTianjin University of TechnologyTianjin300384China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of TechnologyTianjin300384China School of Materials Science and Engineering Tianjin University of TechnologyTianjin300384China

Magnesium alloys with excellent degradability and biocompatibility are promising materials for biomedical implants,saving patients the burden of second ***,their mechanical properties and corrosion resistance are significantly below the requirements for implant *** study aims to improve the mechanical and corrosion resistance properties of Mg-3Zn-0.2Ca alloy by pre-torsion treatment,and find out the optimal shear *** rod-shaped Mg-3Zn-0.2Ca alloy specimens were pre-torsion treated at different torsion *** effect of free-end torsion on Mg-3Zn-0.2Ca alloy was characterized through microstructure analysis,mechanical testing,and corrosion ***-torsion treatment can refine grain and induce twins and dislocations in Mg-3Zn-0.2Ca *** surface hardness increases with the increase in torsion *** yield strength and ultimate strength initially increase and then decrease with increasing torsion angle,while ductility decreases with increasing torsion *** with a shear strain of 30%exhibit the highest tensile strength,reaching 284.78±10.62 MPa,with an elongation of 19.37±1.66%.Furthermore,they show a significant improvement in fatigue lives both before and after *** the stress amplitude is 120 MPa,the fatigue lives for specimens without pre-torsion treatment are 54,275 cycles and 4324 cycles before and after pre-corrosion,while they increased significantly to 92,015 cycles and 5050 cycles with the 30%shear strain,***,the 30%shear strain specimens show a significant reduction in corrosion *** conclusion,pre-torsion treatment can effectively modify the microstructure of Mg-3Zn-0.2Ca alloy,enhancing both mechanical properties and corrosion *** optimal shear strain for this improvement is 30%.This study provides a practical method to enhance the mechanical properties and corrosion resistance of Mg-3Zn-0.2Ca alloy,making it more suitable for biomedical implan

关键词： Magnesium alloy Pre-torsion Microstructure Mechanical property Corrosion resistance

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Nonlinear Disturbance Observer of Clutch Slipping Torque for Multi-Mode Hybrid Electric Vehicles

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Journal of Shanghai Jiaotong University (Science) 2024年 1-8页

作者： Peng, Cheng Chen, Li Fu, Shenglai Key Laboratory of Marine Intelligent Equipment and System of Ministry of Education School of Naval Architecture Ocean & ampCivil Engineering Shanghai Jiao Tong University Shanghai200240 China State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University Shanghai200240 China

Clutch slipping torque varies complicatedly and has a strong nonlinearity during the mode transition of hybrid electric vehicles. In order to estimate the clutch slipping torque, an online estimator based on the nonlinear disturbance observer (NDO) is proposed. First, an estimation-oriented model of the clutch slipping torque is established based on the LuGre friction model. Next, the NDO is designed to estimate the unknown part of clutch slipping torque based on the dynamics of the output shaft, while the output shaft torque required by NDO is estimated by a Luenberger state observer. To verify the effectiveness of the proposed estimator, experiments are conducted under different initial slipping speeds and inlet oil temperatures. The results show that the proposed estimator gains high accuracy. © Shanghai Jiao Tong University 2024.

关键词： Clutches

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Solar evaporation for simultaneous oil-water separation and electricity generation with Janus wood-based absorbers

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Frontiers of Environmental Science & Engineering 2024年第2期18卷 13-23页

作者： Yue Yang Ze Fu Qi Zhang Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse School of Environmental and Biological EngineeringNanjing University of Science&TechnologyNanjing 210094China Key Laboratory of Industrial Ecology and Environmental Engineering(Ministry of Education) School of Environmental Science and TechnologyDalian University of TechnologyDalian 116024China National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced MicrostructuresCollege of Engineering and Applied SciencesKey Laboratory of Intelligent Optical Sensing and Manipulation(Ministry of Education)Jiangsu Key Laboratory of Artificial Functional MaterialsNanjing UniversityNanjing 210093China

Oily wastewater from ocean oil spills endangers marine ecosystems and human health. Therefore, developing an effective and sustainable solution for separating oil-water mixtures is urgent. Interfacial solar photothermal evaporation is a promising approach for the complete separation of two-phase mixtures using only solar energy. Herein, we report a carbonized wood-based absorber with Janus structure of comprising a hydrophobic top-layer and an oleophobic bottom-layer for simultaneous solar-driven oil-water separation and electricity generation. Under sunlight irradiation, the rapid evaporation of seawater will induce a separation of oil-water mixtures, and cause a high salt concentration region underlying the interface, while the bottom “bulk water” maintains in a low salt concentration, thus forming a salinity gradient. Electricity can be generated by salinity gradient power. Therefore, oil-water separation efficiency of > 99% and derived extra electricity power of ~0.1 W/m2 is achieved under solar radiation, demonstrating the feasibility of oil-water separation and electricity production synchronously directly using solar energy. This work provides a green and cost-effective path for the separation of oil-water mixtures.

关键词： Oily wastewater Carbonized wood Salinity gradient Electricity generation Solar irradiation

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Transfer Learning in Motor Imagery Brain Computer Interface: A Review

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Journal of Shanghai Jiaotong university(Science) 2024年第1期29卷 37-59页

作者：李明爱许冬芹 Faculty of Information Technology Beijing University of TechnologyBeijing 100124China Beijing Key Laboratory of Computational Intelligence and Intelligent System Beijing 100124China Engineering Research Center of Digital Community Ministry of EducationBeijing 100124China

Transfer learning,as a new machine learning methodology,may solve problems in related but different domains by using existing knowledge,and it is often applied to transfer training data from another domain for model training in the case of insuficient training *** recent years,an increasing number of researchers who engage in brain-computer interface(BCI),have focused on using transfer learning to make most of the available electroencephalogram data from different subjects,effectively reducing the cost of expensive data acquisition and labeling as well as greatly improving the learning performance of the *** paper surveys the development of transfer learning and reviews the transfer learning approaches in *** addition,according to the"what to transfer"question in transfer learning,this review is organized into three contexts:instance-based transfer learning,parameter-based transfer learning,and feature-based transfer ***,the current transfer learning applications in BCI research are summarized in terms of the transfer learning methods,datasets,evaluation performance,*** the end of the paper,the questions to be solved in future research are put forward,laying the foundation for the popularization and in-depth research of transfer learning in BCI.

关键词： transfer learning brain-computer interface(BCI) electroencephalogram machine learning

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Fault-induced gear meshing modulation sideband extraction and evaluation for fault diagnosis of planetary gearboxes

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Science China(Technological Sciences) 2025年第1期68卷 335-351页

作者： Peng ZHOU Xiaoluo YU Yang YANG Qingbo HE Zhike PENG State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China School of Mechanical Engineering Ningxia UniversityYinchuan 750021China Science and Technology on Vehicle Transmission Laboratory China North Vehicle InstituteBeijing 100072China

Gearboxes,known for their compact size and stable transmission capability,are widely used as power transmission structures in various types of mechanical equipment,such as wind turbines,helicopters,and special ***,due to harsh and non-stationary working conditions,gear surfaces often deteriorate,leading to faults such as wear,pitting,and ***,it is vital to monitor the working status of gearboxes and diagnose gear faults as early as *** faults can induce characteristic modulation effects near the gear meshing frequency(GMF),resulting in the appearance of faultinduced sidebands in a vibration *** of these sidebands allows for the diagnosis of gear faults in a ***,when faced with a planetary gearbox having a complex configuration,strong background noise and additional faultunrelated sidebands can interfere with fault-induced sidebands,making accurate diagnosis *** address these challenging issues,this paper proposes a novel fault-induced gear meshing modulation sideband extraction *** the process,the sidebands directly related to the gear fault near the GMF are first identified and then extracted by a variational harmonic mode decomposition(VHMD)***,a fault-related gear meshing modulation component(GMMC)can be accurately reconstructed by summing up the extracted fault-induced *** the GMMC,the gear fault severity can be assessed by evaluating its amplitude modulation(AM)*** superior performance of the proposed method is finally demonstrated by experimental data.

关键词： planetary gearbox gear meshing frequency modulation sideband signal decomposition fault diagnosis

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A comparative study on mechanical and vibroacoustic performance of sandwich cylindrical shells with positive,negative,and zero Poisson’s ratio cellular cores

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Journal of Ocean Engineering and Science 2024年第4期9卷 379-390页

作者： Qing Li Peichang Li Yongjin Guo Xi’an Liu State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai200240China China Ship Development and Design Center Wuhan430064China MOE Key Laboratory of Marine Intelligent Equipment and System Shanghai Jiao Tong UniversityShanghai200240China

Deep-sea submersibles are significant mobile platforms requiring multi-functional capabilities that are strongly determined by the constituent *** cylindrical protective cover can be advanced by designing their sandwiched cellular materials whose physical properties can be readily parameterized and flexibly *** honeycomb materials are capable of possessing tuned positive,negative,or zero Poisson’s ratios(PPR,NPR,and ZPR),which is expected to produce distinct physical performance when utilized as a cellular core of cylindrical shells for the deep-sea submersibles.A novel cylindrical meta-structure sandwiched with the semi-re-entrant ZPR metamaterial has been designed as well as its similarly-shaped sandwich cylindrical shell structures with PPR and NPR *** mechanical and vibroacoustic performance of sandwich cylindrical shells with cellular materials featuring a full characteristic range of Poisson’s ratios are then compared systematically to explore their potential for engineering applications on submerged pressure-resistant *** respective unit cells are designed to feature an equivalent load-bearing *** properties of pressure resistance,buckling,and sound insulation are simulated,respectively,and the orders of each property are then generalized by systematic *** results indicate that the PPR honeycomb core takes advantage of higher structural strength and stability while the ZPR one yields better energy absorption and sound insulation *** NPR one yields moderate properties and has the potential for lower circumferential *** work explores the application of cellular materials with varied Poisson’s ratios and provides guidance for the multi-functional design of sandwich cylindrical meta-structures.

关键词： Sandwich cylindrical shells Poisson’s ratio Pressure-resistant Buckling Vibroacoustic

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