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Simulation on control of beam halo-chaos by power function in the hackle periodic-focusing channel

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Nuclear Science and Techniques 2008年第6期19卷 325-328页

作者： YU Haijun WENG Jiaqiang bai long Department of Physics Huainan Normal University Huainan 232001 China College of Physics and Information Technology Guangxi Normal University Guilin 541004 China College of Science China University of Mining and Technology Xuzhou 221008 China

The K-V beam through a hackle periodic-focusing magnetic field is studied using the particle-core model. The beam halo-chaos is found, and a power function controller is proposed based on mechanism of halo formation and strategy of controlling halo-chaos. Multiparticle simulation was performed to control the halo by using the power function control method. The results show that the halo-chaos and its regeneration can be eliminated effectively. We also find that the radial particle density evolvement is of uniformity at the beam’s centre as long as appropriate parameters are chosen.

关键词：束晕混沌状态周期性聚焦磁场幂函数核技术

Dynamic modeling of spacecraft solar panels deployment with Lie group variational integrator

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Theoretical & Applied Mechanics Letters 2018年第6期8卷 415-424,I0005页

作者： long bai Xinsheng Ge School of Mechanical and Electrical Engineering Beijing Information Science and Technology University

The spacecraft with multistage solar panels have nonlinear coupling between attitudes of central body and solar panels, especially the rotation of central body is considered in space. The dynamics model is based for dynamics analysis and control, and the multistage solar panels means the dynamics modeling will be very complex. In this research, the Lie group variational integrator method is introduced, and the dynamics model of spacecraft with solar panels that connects together by flexible joints is built. The most obvious character of this method is that the attitudes of central body and solar panels are all described by three-dimensional attitude matrix. The dynamics models of spacecraft with one and three solar panels are established and simulated. The study shows Lie group variational integrator method avoids parameters coupling and effectively reduces difficulty of modeling. The obtained continuous dynamics model based on Lie group is a set of ordinary differential equations and equivalent with traditional dynamics model that offers a basis for the geometry control.

关键词： Lie group Variational integrator Spacecraft Solar panels deployment Dynamics modeling

Optimal Variable Stiffness Control and Its Applications in Bionic Robotic Joints:A Review

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Journal of Bionic Engineering 2023年第2期20卷 417-435页

作者： Yuanxi Sun Yuntao Tang Jia Zheng Dianbiao Dong long bai State Key Laboratory of Mechanical Transmission Chongqing UniversityChongqing400044China School of Advanced Manufacturing Engineering Chongqing University of Posts and TelecommunicationsChongqing400065China School of Mechanical Engineering Northwestern Polytechnical UniversityXi’an710072China

Variable Stiffness Actuation(VSA)is an efficient,safe,and robust actuation technology for bionic robotic joints that have emerged in recent *** introducing a variable stiffness elastomer in the actuation system,the mechanical-electric energy conversion between the motor and the load could be adjusted on-demand,thereby improving the performance of the actuator,such as the peak power reduction,energy saving,bionic actuation,*** present,the VSA technology has achieved fruitful research results in designing the actuator mechanism and the stiffness adjustment servo,which has been widely applied in articulated robots,exoskeletons,prostheses,***,how to optimally control the stiffness of VSAs in different application scenarios for better actuator performance is still challenging,where there is still a lack of unified cognition and ***,from the perspective of optimal VSA performance,this paper first introduces some typical structural design and servo control techniques of common VSAs and then explains the methods and applications of the Optimal Variable Stiffness Control(OVSC)approaches by theoretically introducing different types of OVSC mathematical models and summarizing OVSC methods with varying optimization goals and application scenarios or *** addition,the current research challenges of OVSC methods and possible innovative insights are also presented and discussed in-depth to facilitate the future development of VSA control.

关键词： Bionic robotic joint Variable stiffness actuator Optimal control Robotics Controller design

A hybrid physics-data-driven surface roughness prediction model for ultra-precision machining

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Science China(Technological Sciences) 2023年第5期66卷 1289-1303页

作者： bai long YANG QiZhong CHENG Xin DING Yue XU JianFeng State Key Laboratory of Digital Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan430074China Wuhan Digital Design and Manufacturing Innovation Center Co. LtdWuhan430074China

The surface finish quality is critical to the service performance of a machined part,and single-point diamond ultra-precision machining can achieve excellent surface quality for many engineering *** study studied the problem of predicting the surface roughness for titanium alloy workpieces in ultra-precision *** data and surface roughness measurement results were obtained during end-face machining experiments.A deep learning neural network model was built based on the ResNet-50 architecture to predict surface *** propose increasing prediction accuracy by using the energy ratio difference(ERD)as a stability feature that can be extracted using fast iterative variational mode decomposition(FI-VMD).The roughness value obtained with an analytic model was also used as an input feature of the prediction *** prediction accuracy of the proposed approach was depicted to be improved by 8.7%with the two newly introduced roughness *** influence of the tool parameters on the prediction accuracy was investigated,and the proposed hybrid-driven model exhibited higher robustness to errors of the tool parameters than the analytic roughness model.

关键词： surface roughness ultra-precision machining prediction model stability feature

Vehicle color recognition based on smooth modulation neural network with multi-scale feature fusion

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Frontiers of Computer Science 2023年第3期17卷 91-102页

作者： Mingdi HU long bai Jiulun FAN Sirui ZHAO Enhong CHEN School of Communications and Information Engineering&School of Artificial Intelligence Xi’an University of Posts&TelecommunicationsXi’an 710121China School of Computer Science and Technology University of Science and Technology of ChinaHefei 230026China

Vehicle Color Recognition(VCR)plays a vital role in intelligent traffic management and criminal investigation ***,the existing vehicle color datasets only cover 13 classes,which can not meet the current actual ***,although lots of efforts are devoted to VCR,they suffer from the problem of class imbalance in *** address these challenges,in this paper,we propose a novel VCR method based on Smooth Modulation Neural Network with Multi-Scale Feature Fusion(SMNN-MSFF).Specifically,to construct the benchmark of model training and evaluation,we first present a new VCR dataset with 24 vehicle classes,Vehicle Color-24,consisting of 10091 vehicle images from a 100-hour urban road surveillance ***,to tackle the problem of long-tail distribution and improve the recognition performance,we propose the SMNN-MSFF model with multiscale feature fusion and smooth *** former aims to extract feature information from local to global,and the latter could increase the loss of the images of tail class instances for training with ***,comprehensive experimental evaluation on Vehicle Color-24 and previously three representative datasets demonstrate that our proposed SMNN-MSFF outperformed state-of-the-art VCR *** extensive ablation studies also demonstrate that each module of our method is effective,especially,the smooth modulation efficiently help feature learning of the minority or tail *** Color-24 and the code of SMNN-MSFF are publicly available and can contact the author to obtain.

关键词： vehicle color recognition benchmark dataset multi-scale feature fusion long-tail distribution improved smooth l1 loss

Extremes of threshold-dependent Gaussian processes

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Science China Mathematics 2018年第11期61卷 1971-2002页

作者： long bai Krzysztof Debicki Enkelejd Hashorva Lanpeng Ji Department of Actuarial Science University of Lausanne Mathematical Institute University of Wroclaw School of Mathematics University of Leeds

In this paper,we are concerned with the asymptotic behavior,as u→∞,of P{sup_t∈|0,T|X_u(t)>u},where X_u(t),t∈|0,T|,u>0 is a family of centered Gaussian processes with continuous trajectories.A key application of our findings concerns P{sup_t∈|0,T|(X(t)+g(t))>u},as u→∞,for X a centered Gaussian process and g some measurable trend *** applications include the approximation of both the ruin time and the ruin probability of the Brownian motion risk model with constant force of interest.

关键词： extremes Gaussian processes fractional Brownian motion ruin probability ruin time

Effect of enamel top coating on oxidation behavior of multi-arc ion plating NiCrAlY coating in oxygen containing water vapor

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中国有色金属学会会刊：英文版 2004年第z1期14卷 446-450页

作者： XIE Dong-bai ZHU Sheng-long WANG Fu-hui State Key Laboratory for Corrosion and Protection Institute of Metal Research Chinese Academy of Science Shenyang 110016 China State Key Laboratory for Corrosion and Protection Institute of Metal Research Chinese Academy of Science Shenyang 110016 China State Key Laboratory for Corrosion and Protection Institute of Metal Research Chinese Academy of Science Shenyang 110016 China

The oxidation behavior of Ni-Cr-Al-Y coating produced by multi-arc ion plating with and without an enamel coating was investigated in flow oxygen and oxygen containing water vapor at 900 ℃. The results show that Ni-Cr-Al-Y coating exhibits low oxidation rate at 900 ℃ in pure oxygen and the oxidation kinetics follow the parabolic rate law. The presence of water vapor accelerates the oxidation rate of Ni-Cr-Al-Y coating and K38G *** enamel top coating is very effective in protecting the Ni-Cr-Al-Y coating from water vapor corrosion attack, but the corrosion attack beneath the enamel coating is not observed.

关键词： water vapor enamel coating Ni-Cr-Al-Y coating oxidation

Surface roughness classification using light scattering matrix and deep learning

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Science China(Technological Sciences) 2024年第2期67卷 520-535页

作者： SUN Hao TAN Wei RUAN YiXiao bai long XU JianFeng State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China Wuhan Digital Design and Manufacturing Innovation Center Co. LtdWuhan 430074China

High-quality optical components have been widely used in various applications;thus,extremely high beam quality is ***,surface roughness is a key indicator of the surface *** this study,the angular distribution of light scattering field intensity was obtained for surfaces having different roughness profiles based on the finite difference time domain(FDTD)method,and the results were compared with those obtained using the generalized Harvey-Shack(GHS)*** was shown that the FDTD approach can be used for an accurate simulation of the scattered field of a rough surface,and the superposition of results obtained from many surfaces that have the same roughness level was in good agreement with the result given by the analytic GHS model.A light scattering matrix(LSM)method was proposed based on the FDTD simulation results that could obtain rich surface roughness *** classification effect of LSM was compared with that of the single-incidence scattering distribution(SISD)based on a ResNet-50 deep learning *** classification accuracy of the model trained with the LSM dataset was obtained as 95.74%,which was 23.40%higher than that trained using the SISD ***,the effects of different noise types and filtering methods on the classification performance were analyzed,and the LSM was also shown to improve the robustness and generalizability of the trained surface roughness ***,the proposed LSM method has important implications for improving the data acquisition scheme of current light scattering measurement systems,and it also has the potential to be used for detection and characterization of surface defects of optical components.

关键词： surface roughness FDTD simulation GHS theory deep learning light scattering matrix

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Response of a transmission tower-line system at a canyon site to spatially varying ground motions

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第2期12卷 103-120页

作者： Hong-nan LI Feng-long bai Li TIAN Hong HAO State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116024 China Sehool of Civil and Resource Engineering University of Western Australia WA 6009 Australia

Collapses of transmission towers were often observed in previous large earthquakes such as the Chi-Chi earthquake in Taiwan and Wenchuan earthquake in Sichuan,China. These collapses were partially caused by the pulling forces from the transmission lines generated from out-of-phase responses of the adjacent towers owing to spatially varying earthquake ground motions. In this paper,a 3D finite element model of the transmission tower-line system is established considering the geometric nonlinearity of transmission lines. The nonlinear responses of the structural system at a canyon site are analyzed subjected to spatially varying ground motions. The spatial variations of ground motion associated with the wave passage,coherency loss,and local site effects are given. The spatially varying ground motions are simulated stochastically based on an empirical coherency loss function and a filtered Tajimi-Kanai power spectral density function. The site effect is considered by a transfer function derived from 1D wave propagation theory. Compared with structural responses calculated using the uniform ground motion and delayed excitations,numerical results indicate that seismic responses of transmission towers and power lines are amplified when considering spatially varying ground motions including site effects. Each factor of ground motion spatial variations has a significant effect on the seismic response of the structure,especially for the local site effect. Therefore,neglecting the earthquake ground motion spatial variations may lead to a substantial underestimation of the response of transmission tower-line system during strong earthquakes. Each effect of ground motion spatial variations should be incorporated in seismic analysis of the structural system.

关键词： Transmission tower-line system Canyon site Spatially varying ground motions Coherency loss Local site effect