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FeCrNiCoCu合金疲劳性能及缺陷演变的分子动力学研究

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原子与分子物理学报 2025年第4期42卷 81-86页

作者：朱和军常州工业职业技术学院常州213164

疲劳失效是机械构件的重要失效形式之一,因此本文通过分子动力学模拟方法在应变量ε=0.08下,对高熵合金FeCrNiCoCu合金进行20次循环加载模拟,以探究了高熵合金FeCrNiCoCu合金的疲劳力学性能和组织演变.结果发现,在循环加载过程中,FeCrNi... 详细信息

疲劳失效是机械构件的重要失效形式之一,因此本文通过分子动力学模拟方法在应变量ε=0.08下,对高熵合金FeCrNiCoCu合金进行20次循环加载模拟,以探究了高熵合金FeCrNiCoCu合金的疲劳力学性能和组织演变.结果发现,在循环加载过程中,FeCrNiCoCu模型存在明显的循环软化和循环硬化现象,且循环软化和循环硬化交替出现.通过对模型组织分析发现每个循环周期结束后,有残余位错和层错,这些缺陷直接影响到下一周期的疲劳应力.通过对模型中总能量和无序原子百分比的统计分析可知,模型的总能量呈升高的趋势.模型中无序原子的百分比逐渐升高,最后稳定在0.09左右,无序原子对位错的生成和湮灭有直接的影响,进而影响循环硬化和循环软化.

关键词：循环加载分子动力学疲劳变形微观缺陷演化

Karhunen-loéve expansion for random earthquake excitations

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Earthquake Engineering and Engineering Vibration 2015年第1期14卷 77-84页

作者： he jun Department of Civil Engineering Shanghai Jiaotong University

This paper develops a trigonometric-basis-fimction based Karhunen-Loeve （KL） expansion for simulating random earthquake excitations with known covariance functions. The methods for determining the number of the KL terms and defining the involved random variables are described in detail. The simplified form of the KL expansion is given, whereby the relationship between the KL expansion and the spectral representation method is investigated and revealed. The KL expansion is of high efficiency for simulating long-term earthquake excitations in the sense that it needs a minimum number of random variables, as compared with the spectral representation method. Numerical examples demonstrate the convergence and accuracy of the KL expansion for simulating two commonly-used random earthquake excitation models and estimating linear and nonlinear random responses to the random excitations.

关键词： Karhunen-loeve expansion trigonometric basis function Galerkin method random earthquake excitation random response

Experimental investigation and analytically modeling of hysteretic behavior of rigid bus-flexible connectors of 220 kV electrical substations

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Earthquake Engineering and Engineering Vibration 2023年第3期22卷 841-852页

作者： Tang Tingxuan he jun Department of Civil Engineering School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

This paper describes the quasi-static testing and analytical modelling of the hysteretic behavior of aluminum alloy rigid bus-flexible connectors of 220 kV electrical *** main objective of the study is to experimentally investigate the hysteretic behavior of six different types of rigid bus-flexible connectors 220 kV electrical substations when subjected to cyclic *** objective is to theoretically study the flexibility and effectiveness of a previously proposed analytical model in fitting the experimental hysteresis loops of the tested rigid bus-flexible *** experimental investigation indicates that the tested rigid bus-flexible connectors exhibit highly asymmetric hysteresis behavior along with tension stiffening *** theoretical study demonstrates that the generalized Bouc-Wen model has high flexibility and is effective in fitting the experimental hysteresis resisting force-displacement curves of the six tested rigid bus-flexible connectors.

关键词： rigid bus-flexible connectors 220 kV electrical substations hysteretic behavior experimental curves analytical model

Mechanism,Actuation,Perception,and Control of Highly Dynamic Multilegged Robots:A Review

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Chinese Journal of Mechanical Engineering 2020年第5期33卷 120-149页

作者： jun he Feng Gao State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Multilegged robots have the potential to serve as assistants for humans,replacing them in performing dangerous,dull,or unclean ***,they are still far from being sufficiently versatile and robust for many *** paper addresses key points that might yield breakthroughs for highly dynamic multilegged robots with the abilities of running(or jumping and hopping)and ***,21 typical multilegged robots from the last five years are surveyed,and the most impressive performances of these robots are ***,current developments regarding key technologies of highly dynamic multilegged robots are reviewed in *** latest leg mechanisms with serial-parallel hybrid topologies and rigid–flexible coupling configurations are ***,the development trends of three typical actuators,namely hydraulic,quasi-direct drive,and serial elastic actuators,are *** that,the sensors and modeling methods used for perception are ***,this paper pays special attention to the review of control approaches since control is a great challenge for highly dynamic multilegged *** dynamics-based control methods and two model-free control methods are described in ***,key open topics of future research concerning the mechanism,actuation,perception,and control of highly dynamic multilegged robots are *** paper reviews the state of the art development for multilegged robots,and discusses the future trend of multilegged robots.

关键词： Multilegged robot Mechanism Actuation Perception Control

Continuity of the Solution to the L_(p) Minkowski Problem in Gaussian Probability Space

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Acta Mathematica Sinica,English Series 2022年第12期38卷 2253-2264页

作者： he jun WANG School of Mathematics and Statistics Shandong Normal UniversityJi'nan 250358P.R.China

In this paper,it is proved that the weak convergence of the L_(p) Gaussian surface area measures implies the convergence of the corresponding convex bodies in the Hausdorff metric for p≥***,continuity of the solution... 详细信息

关键词： L_(p)Gaussian Minkowski problem L_(p)Gaussian surface area measure continuity convex body

Posterior probability calculation procedure for recognition rate comparison

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Journal of Systems Engineering and Electronics 2016年第3期27卷 700-711页

作者： jun he Qiang Fu Science and Technology on Automatic Target Recognition Laboratory College of Electronic Science and EngineeringNational University of Defense Technology

This paper focuses on the recognition rate comparison for competing recognition algorithms, which is a common problem of many pattern recognition research areas. The paper firstly reviews some traditional recognition rate comparison procedures and discusses their limitations. A new method, the posterior probability calculation（PPC） procedure is then proposed based on Bayesian technique. The paper analyzes the basic principle, process steps and computational complexity of the PPC procedure. In the Bayesian view, the posterior probability represents the credible degree（equal to confidence level） of the comparison results. The posterior probability of correctly selecting or sorting the competing recognition algorithms is derived, and the minimum sample size requirement is also pre-estimated and given out by the form of tables. To further illustrate how to use our method, the PPC procedure is used to prove the rationality of the experiential choice in one application and then to calculate the confidence level with the fixed-size datasets in another application. These applications reveal the superiority of the PPC procedure, and the discussions about the stopping rule further explain the underlying statistical causes. Finally we conclude that the PPC procedure achieves all the expected functions and be superior to the traditional methods.

关键词： pattern recognition performance evaluation algorithm uncertainty analysis

Type Synthesis for Bionic Quadruped Walking Robots

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Journal of Bionic Engineering 2015年第4期12卷 527-538页

作者： jun he Feng Gao State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai 200240 China

Regarding walking robots, biomimetic design has attracted a great deal of attention. Currently, studies have focused mainly on performance analysis and the design of some specific biomimetic walking robots. However, the systematic type synthesis of bionic quadruped robots has seldom been studied. In this paper, a new approach to type synthesis for quadruped walking robots is proposed based on the generalized fimction （Ge） set theory. The current types of typical walking robots are analyzed using the Ge set theory. The research status and existing problems are investigated. The skeletal systems of quadruped mammals are analyzed. The motion characteristics of all joints of quadruped mammals are denoted by 6;F sets. A process of conversion from biological types to serial, parallel and hybrid types is proposed. Limb types in serial, parallel and hybrid topology are synthe- sized. Finally the quadruped robots with serial, parallel and hybrid topology are produced. Two of these types have been suc- cessfully used for the design of walking rescue robots that is suitable for responding to nuclear accidents.

关键词： type synthesis bionic design quadruped robot parallel mechanism GF set

Amphiphilic Dendrimer-like Copolymers with High Chain Density by Living Anionic Polymerization

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Chinese Journal of Polymer Science 2019年第9期37卷 875-883页

作者： Ke Zheng jun-Po he State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular Science Fudan University

We report here a method for the preparation of amphiphilic dendrimer-like copolymers with dendritic polystyrene (PS) core and protonated poly(2-vinyl pyridine)(P2VP) or poly(methacrylic acid)(PMAA) shell. The method employed the efficient coupling reaction of anionic living polymer chains and chlorosilane. The synthesis started from a functionalized 3rd generation dendritic polystyrene, G3PS-g-SiCl, used as the precursor. The dendrimer-like copolymer of styrene and 2-vinyl pyridine, G3PS-g-P2VP, was synthesized by direct coupling of living P2VPLi to the precursor. The dendrimer-like copolymer of styrene and Zer/-butyl methacrylate, G3PS-g-PtBMA, was synthesized by an indirect procedure in which a living polymer containing mainly PtBMA segment was attached to the precursor. Both methods resulted in the formation of dendrimer-like copolymers with the high molecular weights (up to 8.5 × 10^6 Da), large molecular sizes (diameter up to 73 nm), and dense shells (number of arms up to 1300). These products, G3PS-g-P2VP and G3PS-g- PtBMA, were protonated with trifluoroacetic acid and acidic hydrolyzed, respectively. After transformation, amphiphilic dendrimer-like copolymers, G3PS-g-P2VPH^+ and G3PS-g-PMAA, were obtained. Preliminary results on the solution properties of the amphiphilic products were presented.

关键词： Dendrimer-like polymer Living anionic polymerization Amphiphilic copolymer

Study of primordial deuterium abundance in Big Bang nucleosynthesis

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Nuclear Science and Techniques 2024年第3期35卷 208-215页

作者： Zhi-Lin Shen Jian-jun he Key Laboratory of Beam Technology of Ministry of Education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China Institute of Radiation Technology Beijing Academy of Science and TechnologyBeijing 100875China

Big Bang nucleosynthesis(BBN)theory predicts the primordial abundances of the light elements^(2) H(referred to as deuterium,or D for short),^(3)he,^(4)he,and^(7) Li produced in the early *** these,deuterium,the first nuclide produced by BBN,is a key primordial material for subsequent *** date,the uncertainty in predicted deuterium abundance(D/H)remains larger than the observational *** this study,the Monte Carlo simulation code PRIMAT was used to investigate the sensitivity of 11 important BBN reactions to deuterium *** found that the reaction rate uncertainties of the four reactions d(d,n)^(3)he,d(d,p)t,d(p,γ)^(3)he,and p(n,γ)d had the largest influence on the calculated D/H ***,the calculated D/H uncertainty cannot reach observational precision even with the recent LUNA precise d(p,γ)^(3) he *** the nuclear physics aspect,there is still room to largely reduce the reaction-rate uncertainties;hence,further measurements of the important reactions involved in BBN are still necessary.A photodisintegration experiment will be conducted at the Shanghai Laser Electron Gamma Source Facility to precisely study the deuterium production reaction of p(n,γ)d.

关键词： Big Bang nucleosynthesis Abundance of deuterium Reaction cross section Reaction rate Monte Carlo method