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Chinese Annals of Mathematics,Series B 2024年第5期45卷 805-822页

作者： jian-xin LIU zhi-qiang GAO School of Mathematical Sciences Beijing Normal UniversityBeijing 100875China Laboratory of Mathematics and Complex Systems(Ministry of Education) School of Mathematical SciencesBeijing Normal UniversityBeijing 100875China

Consider a branching random walk with a random environment in time in the d-dimensional integer *** branching mechanism is governed by a supercritical branching process,and the particles perform a lazy random walk with an independent,non-identical increment *** A■Z^(d),let Z_(n)(A)be the number of offsprings of generation n located in *** exact convergence rate of the local limit theorem for the counting measure Z_(n)(·)is *** partially extends the previous results for a simple branching random walk derived by Gao(2017,*** Appl.).

关键词： Branching random walk Random environment Local limit theorems Exact convergence rate

Adaptive command filter constraint control of rolling mill torsional vibration under current harmonic

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Journal of Iron and Steel Research International 2023年第9期30卷 1782-1791页

作者： Shu-zong Chen Cheng jia Chang-chun Hua jia-qiang Chen Institute of Electrical Engineering Yanshan UniversityQinhuangdao 066004HebeiChina

An adaptive command filter control strategy was proposed to realize the asymptotic tracking of the roll speed,which successfully suppressed torsional vibration for the main drive system of the rolling mill with nonlinear friction,nonlinear damping,current harmonic,time-varying stiffness and unknown disturbance.A finite time predetermined performance method was proposed,so that the speed tracking error of the main transmission system was always constrained in the performance function and converged to its minimum boundary within the specified *** on the adaptive estimation of harmonic amplitude,the torque control law of the motor was obtained by using the filter backstepping method,which prevented the torsional vibration of the system caused by the input fluctuation and avoided the complexity explosion of the controller design,and the stability of the closed-loop system was strictly proved by the Lyapunov *** actual numerical simulation verified the effectiveness of the proposed control strategy.

关键词： Main drive system Torsional vibration Command filter Finite time predetermined performance

A curve-based material recognition method in MeV dual-energy X-ray imaging system

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Nuclear Science and Techniques 2016年第1期27卷 13-20页

作者： zhi-qiang Chen Tiao Zhao Liang Li Department of Engineering Physics Tsinghua University Key Laboratory of Particle and Radiation Imaging (TsinghuaUniversity) Ministry of Education

High-energy dual-energy X-ray digital radiography imaging is mainly used in the material recognition of cargo inspection. We introduce the development history and principle of the technology and describe the data process flow of our system. The system corrects original data to get a dual-energy transparence image. Material categories of all points in the image are identified by the classification curve,which is related to the X-ray energy spectrum. For the calibration of classification curve, our strategy involves a basic curve calibration and a real-time correction devoted to enhancing the classification accuracy. Image segmentation and denoising methods are applied to smooth the image. The image contains more information after colorization. Some results show that our methods achieve the desired effect.

关键词： X射线成像系统校准曲线材料识别识别方法数据处理流程透明图像分类精度实时校正

二维光晶格中旋转玻色-爱因斯坦凝聚基态中的涡旋分布

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原子与分子物理学报 2025年第1期42卷 118-126页

作者：张志强王平平吕亚南郑州商学院大学物理教研室郑州451200

利用多重网格预条件共轭梯度法,研究了囚禁在二维光晶格与谐振势组成的复合势阱中的旋转玻色-爱因斯坦凝聚体中的涡旋分布,探讨了光晶格深度、晶格常数和凝聚体旋转频率对旋转凝聚体中涡旋分布的影响.结果表明,由于光晶格势阱的引入,凝... 详细信息

利用多重网格预条件共轭梯度法,研究了囚禁在二维光晶格与谐振势组成的复合势阱中的旋转玻色-爱因斯坦凝聚体中的涡旋分布,探讨了光晶格深度、晶格常数和凝聚体旋转频率对旋转凝聚体中涡旋分布的影响.结果表明,由于光晶格势阱的引入,凝聚体中产生涡旋,且涡旋位于外部势阱极小值处.随着光晶格势阱深度的增加,凝聚体集聚在光晶格势阱的底部,形成格点状分布,其中的涡旋形成涡旋对,并融合形成更大的涡旋.在晶格常数较小时,凝聚体中涡旋分布形成类似Abrikosov涡旋晶格,随着晶格常数的增加,凝聚体中涡旋的分布形式出现多样化,出现了内中外三层结构.随着旋转频率的增加,凝聚体中涡旋数目也随之增加,涡旋分布也更加复杂和富于变化,凝聚体密度分布范围也随着旋转频率的增加而扩展.当凝聚体旋转频率接近外部谐振势阱的谐振频率,即凝聚体处于最低朗道能级近似时,其中的涡旋数量大幅度增加,且出现涡旋成对组合与融合现象,并形成了涡旋斑图花纹.

关键词：波色-爱因斯坦凝聚涡旋二维光晶格复合势阱

Analysis of a new 5-phase bearingless induction motor

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第8期8卷 1311-1319页

作者： HUANG Jin KANG Min YANG jia-qiang School of Electrical Engineering Zhejiang University Hangzhou 310027 China

This paper addresses the bearingless motor with a single set of multiphase windings. The interaction between M and M±1 pole-pair magnetic fields produces radial force. Based on this principle,a bearingless machine is obtained. Conventional bearingless machine has dual windings,levitation windings and torque windings,which produce the two magnetic fields. In the proposed bearingless motor,the two needed magnetic fields are produced by feeding two groups of currents to a single set of multiphase windings. Taking a 5-phase induction motor as example,the inductance matrices,considering air gap eccentricity,are calculated with the modified winding function method. The radial force analytical model is deduced by virtual displacement,and its results are validated by FEA. The mathematical model of the new bearingless machine is set up,and the simulation results verified the feasibility of this novel bearingless motor.

关键词： Air-gap-flux-oriented control Bearingless motor Multiphase Radial force Single set of windings Modified winding function method

Diagnosis of stator faults in induction motor based on zero sequence voltage after switch-off

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第2期9卷 165-172页

作者： jia-qiang YANG Jin HUANG Tong LIU School of Electrical Engineering Zhejiang University Hangzhou 310027 China

To improve the accuracy of the stator winding fault diagnosis in induction motor,a new diagnostic method based on the Hilbert-Huang transform(HHT)was *** ratio of fundamental zero sequence voltage to positive sequence voltage after switch-off was selected as the stator fault characteristic,which could effectively avoid the influence of the supply unbalance and the load fluctuation,and directly represent the asymmetry in the *** the empirical mode decomposition(EMD)based on HHT,the zero sequence voltage after switch-off was decomposed and the fundamental component was ***,the fault characteristic can be *** results on a 4-kW induction motor demonstrate the feasibility and effectiveness of this method.

关键词： Induction motor Stator fault diagnosis Hilbert-Huang transform (HHT) Zero sequence voltage Empirical modedecomposition (EMD)

A numerical study of hydrodynamic influence on collision of brash ice with a structural plate

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Journal of Hydrodynamics 2022年第1期34卷 43-51页

作者： Li Zhou zhi Zong jia-nan Li School of Naval Architecture Dalian University of TechnologyDalian116024China Tianjin Branch HuaDian Heavy Industries Co.Ltd Tianjin300010China

The ice-structure collision is a transient process, which is further complicated by the presence of the water. It remains unclear how important the hydrodynamic influences are during the collision. This problem is partially investigated in this paper using numerical methods. To simplify the problem as much as possible without loss of generality, a short ice cylinder of circular section is assumed to collide with a vertical large structure plate under a variety of collision scenarios. Among them the most important cases are: (1) the rigid ice cylinder collision with the rigid or elastic structural plate at different collision velocities, (2) the elastic ice cylinder collision with the rigid or elastic structural plate at different collision velocities and (3) the elastoplastic ice cylinder collision with the rigid or elastic structural plate at different collision velocities. The numerical results show that: (1) the hydrodynamic influences are negligible in the first case, (2) the hydrodynamic influences in the second and third cases are not negligible, and become very significant in the third case. The influences are numerically estimated to be in the range of 20%–60% in terms of the momentum change. If the ice response is approximately decomposed into the rigid-body motions and the deformation modes at the instant of the collision with the structure, the previous conclusions show that the hydrodynamic influences on the rigid-body motions of the ice are negligible, but those on the elastic and elastoplastic modes of the ice are significant. Comparison with the case of a submerged ice cylinder (although not a practical case) reveals that the hydrodynamic influences are small in the first case due to the fact that the energy loss is used to produce the water splash and the cavity behind the ice cylinder. Through this study we come into the conclusion that the hydrodynamic influences are not important for the rigid-body motions, but important for the elastic or elastop

关键词： Ice-structure collision hydrodynamic influence numerical rigid mode elastic mode

Rational Design of Biomolecules/Polymer Hybrids by Reversible Deactivation Radical Polymerization (RDRP) for Biomedical Applications

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Chinese Journal of Polymer Science 2021年第9期39卷 1093-1109页

作者： Jie Zhou Xiao-Yuan Zhang zhi-qiang Su State Key Laboratory of Chemical Resource Engineering Beijing Key Laboratory of Advanced Functional Polymer CompositesBeijing University of Chemical TechnologyBeijing 100029China

Hybrids,produced by hybridization of proteins,peptides,DNA,and other new biomolecules with polymers,often have unique functional *** properties,such as biocompatibility,stability and specificity,lead to various smart *** review mainly introduces biomolecule polymer hybrid materials by reversible deactivation radical polymerization(RDRP),emphasizing reverse addition-fragmentation chain transfer(RAFT)polymerization,and nitroxide mediated polymerization(NMP).It includes the methods of RDRP to improve the biocompatibility of biomedical materials and organisms by surface *** key to the current synthesis of biomolecule polymer hybrids is to control ***,this review describes several different kinds of biomolecule polymer hybrid materials and their applications in the biomedical *** progresses provide ideas for the investigation of biodegradable and highly bioactive biomedical soft tissue *** research hotspots of nanotechnology in biomedical fields are controlled drug release materials and gene therapy carrier *** showed that RDRP method could improve the therapeutic effect and reduce the dosage and side effects of the ***,by means of RDRP,the original materials can be modified to develop intelligent polymer materials as membrane materials with selective permeability and surface modification.

关键词： Biomolecule-polymer hybrids RDRP Biomedical applications Drug release Nanotechnology

Payne Effect and Weak Overshoot in Rubber Nanocomposites

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Chinese Journal of Polymer Science 2022年第1期40卷 85-92页

作者： zhi-Yun Li Yi-Hu Song qiang Zheng MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027China

Payne effect and its associated weak overshoot are of importance for understanding and regulating the softening of rubber nanocomposites under large amplitude ***,Payne effect in diverse filled vulcanizates is investigated for generalizing the common *** curves of strain amplitude dependent storage modulus are created with respect to microscopic strain amplitude of the matrix,revealing a matrix-dominated elastic nonlinearity being independent of type and dispersity of filler,crosslinking density and sol fraction of matrix and filler-rubber interfacial ***,carbonaceous fillers with higher affinity to the rubber matrices yield lower strain amplification and higher overshoot behavior in comparison with siliceous *** investigation would be illuminating for preparing rubber nanocomposites with optimized reinforcement and softening performances.

关键词： Vulcanizate nanocomposites Payne effect Weak overshoot

Preparation of crystalline rare earth carbonates with large particle size from the lixivium of weathered crust elution-deposited rare earth ores

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International Journal of Minerals,Metallurgy and Materials 2020年第11期27卷 1482-1488页

作者： Jing-qun Yin zhi-qiang Zou Jun Tian Institute of Applied Chemistry Jiangxi Academy of SciencesNanchang 330029China School of Resource and Environmental Engineering Jiangxi University of Science and TechnologyGanzhou 341000China

Crystalline rare-earth(RE)carbonates having large particle size were prepared from the lixivium of weathered crust elution-deposited rare-earth ores using the precipitation method with ammonium bicarbonate as the *** chemical composition was studied using elemental and thermogravimetric analyses(TGA),and their structure and morphology were characterized using Fourier transform infrared(FTIR)spectroscopy,X-ray diffraction(XRD),and scanning electron microscopy(SEM).The results demonstrate that the crystalline rareearth carbonate is a hydrated basic carbonate or oxycarbonate and not astable intermediate carbonate in the process of thermal *** particle size of crystalline rare-earth carbonates with large particle size is in the range of 50–200μ*** an RE2O3 content of up to 95wt%,the quality of crystalline rare-earth carbonates is higher compared to the Chinese National Standard(GB/T 28882–2012).The quality of the product is superior to the Chinese National Standard.

关键词： rare-earth ores precipitation crystalline rare-earth carbonate large particle size