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Rare Metals 2024年第5期43卷 2275-2281页

作者： Guo-Chao Li Xu Cheng hua-ming wang National Engineering Laboratory of Additive Manufacturing for Large Metallic Components and Engineering Research Center of Ministry of Education on Laser Direct Manufacturing for Large Metallic Components School of Materials Science and EngineeringBeihang UniversityBeijing 100191China

The solid solution and aging treatment for conventional manufacturing processes might not be suitable for laser additive manufactured titanium alloys due to the different lamellar *** this study,the influence of aging temperatures(600,700 and 800°C)on microstructure and mechanical properties of titanium alloy Ti-6Al-2V-1.5Mo-0.5Zr-0.3Si was *** results indicate that after solid solution treatment at 970°C followed by water quenching,the alloy mainly consists of coarsening lamellar a phase in martensite α' *** at 600°C will not change the size of primary lamellar α phase but lead to huge amount of secondary a phases(α_(s))generating with very fine *** increasing the aging temperature,the number of α_(s) decreases but with coarsened *** aged at 800°C,the width of the asphase reaches 350 nm,almost 7 times wider than that aged at 600°*** changing size of α_(s) obviously influences the property of the *** fine α_(s) leads to high strength and microhardness but low plasticity,and specimen aged at 700°C with suitable assize has the best comprehensive properties.

关键词： α+βtitanium alloy Laser additive manufacturing Solid solution and aging treatment Microstructure Room temperature tensile property

Times of a Branching Process with Immigration in Varying Environments Attaining a Fixed Level

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Acta Mathematica Sinica,English Series 2024年

作者： hua-ming wang School of Mathematics and Statistics Anhui Normal University

Consider a branching process{Z_n}n≥0with immigration in varying *** a∈{0,1,2,...},let C（a）={n≥0:Z_n=a}be the collection of times at which the population size of the process attains level *** give a criterion to determine whether the set C（a） is finite or *** the critical Galton-Watson process,based on a moment method,we show that|C（a）∩[1,n]|/log n→Sin distribution,where S is an exponentially distributed random variable with P （S>t）=e-t,t>0.

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变环境下两物种分枝过程灭绝时的极限定理

中国科学：数学 2024年第6期54卷 839-862页

作者：王华明安徽师范大学数学与统计学院芜湖241003

考虑变环境下两物种分枝过程.假定系统中个体的后代分布为线性分式分布且后代分布的均值矩阵存在极限,设ν为过程的灭绝时,且对k1记M_(k)为第k-1代个体的后代均值矩阵.在一定条件下,本文证明当n→∞时,P(ν=n)和P(ν>n)渐近等价于后代... 详细信息

考虑变环境下两物种分枝过程.假定系统中个体的后代分布为线性分式分布且后代分布的均值矩阵存在极限,设ν为过程的灭绝时,且对k1记M_(k)为第k-1代个体的后代均值矩阵.在一定条件下,本文证明当n→∞时,P(ν=n)和P(ν>n)渐近等价于后代均值矩阵谱半径乘积的一些函数,推广了wang和Yao(2022)的结论.wang和Yao(2022)需要一个特定的假设,即存在ε>0使得对于任意k1,有det(M_(k))<-ε.在该假设下,系统中的个体更倾向于产生另一个物种的子女,故而将一大类矩阵排除在均值矩阵之外.本文去除了这一额外的假设,研究了灭绝时的分布极限理论.此外,为证明灭绝时的极限定理,本文用谱半径乘积给出了非齐次2阶矩阵乘积内部元素极限行为的等价刻画,并得到渐近周期连分数一些精细的极限定理.这些结论在非齐次矩阵乘积的遍历理论及连分数的极限理论中也自有其意义.

关键词：变环境下分枝过程灭绝时非齐次矩阵乘积谱半径连分数

On Total Progeny of Multitype Galton-Watson Process and the First Passage Time of Random Walk on Lattice

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Acta Mathematica Sinica,English Series 2014年第12期30卷 2161-2172页

作者： hua ming wang Department of Mathematics Anhui Normal University

In this paper,we form a method to calculate the probability generating function of the total progeny of multitype branching *** examples,we calculate probability generating function of the total progeny of the multitype branching processes within random walk which could stay at its position and（2-1） random ***,we could give the probability generating functions and the distributions of the first passage time of corresponding random ***,for recurrent random walk which could stay at its position with probability 0 〈 r 〈 1,we show that the tail probability of the first passage time decays as 2/√π（1-r）1/√n= when n →∞.

关键词： Multitype branching process total progeny random walk

A Note on Multitype Branching Process with Bounded Immigration in Random Environment

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Acta Mathematica Sinica,English Series 2013年第6期29卷 1095-1110页

作者： hua ming wang Department of Mathematics Anhui Normal University

In this paper, we study the total number of progeny, W, before regenerating of multitype branching process with immigration in random environment. We show that the tail probability of ｜W｜ is of order t-κ as t→∞, with κ some constant. As an application, we prove a stable law for （L-1） random walk in random environment, generalizing the stable law for the nearest random walk in random environment （see ＂Kesten, Kozlov, Spitzer： A limit law for random walk in a random environment. Compositio Math., 30, 145-168 （1975）＂）.

关键词： Branching process random walk random environment

Triphenylphosphine as Reducing Agent for Copper(II)-catalyzed AGET ATRP

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Chinese Journal of Polymer Science 2015年第9期33卷 1260-1270页

作者：柏良久 Wen-xiang wang ming-hua wang Jin-ming Sun 陈厚 School of Chemistry and Materials Science Ludong University

Triphenylphosphine （TPP） was used as reducing agent to continuously generate the Cu（I） activator in copper（II）- catalyzed activators generated by electron transfer atom transfer radical polymerization （AGET ATRP）. For example, the polymers prepared with a molar ratio of [MMA]0/[EBiB]0/[CuC12]o/[PMDETA]0/[TPP]o = 500/1/0.1/0.5/0.5 had controlled molecular weights and low molecular weight distribution （Mw/Mn） values （-1.2）. TPP as a commercial reducing agent provides a convenient copper-catalyzed AGET ATRP procedure for the preparation of well-defined polymers.

关键词： ATRP AGET ATRP Reducing agent Triphenylphosphine (TPP).

A Class of New Large-Update Primal-Dual Interior-Point Algorithms for P＊（k） Nonlinear Complementarity Problems

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Acta Mathematica Sinica,English Series 2011年第10期27卷 1979-1994页

作者： hua Ping CHEN ming wang ZHANG College of Science China Three Gorges University Yichang 443002 P. R. China

In this paper we propose a class of new large-update primal-dual interior-point algorithms for P.（k） nonlinear complementarity problem （NCP）, which are based on a class of kernel functions investigated by Bai et al. in their recent work for linear optimization （LO）. The arguments for the algorithms are followed as Peng et al.＇s for P.（n） complementarity problem based on the self-regular functions [Peng, J., Roos, C., Terlaky, T.： Self-Regularity： A New Paradigm for Primal-Dual Interior- Point Algorithms, Princeton University Press, Princeton, 2002]. It is worth mentioning that since this class of kernel functions includes a class of non-self-regular functions as special case, so our algorithms are different from Peng et al.＇s and the corresponding analysis is simpler than theirs. The ultimate goal of the paper is to show that the algorithms based on these functions have favorable polynomial complexity.

关键词： Large-update method interior-point algorithm nonlinear complementarity problem non- self-regular function polynomial complexity

Improvement of proof-ultimate strength difference in laser additive manufactured Ti-6Al-2V-1.5Mo-0.5Zr-0.3Si alloy by tuning basketweave structure

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Journal of Iron and Steel Research International 2019年第6期26卷 631-636页

作者： Guo-chao Li Xu Cheng hua-ming wang National Engineering Laboratory of Additive Manufacturing for Large Metallic Components and Engineering Research Center of Ministry of Education on Laser Direct Manufacturing for Large Metallic Components School of Materials Science and Engineering Beihang University Beijing 100191 China Beijing Yuding Additive Manufacturing Research Institute Co. Ltd. Beijing 102206 China

After annealed at 1000 ℃, a special basket-weave structure is obtained in laser additive manufactured Ti-6Al-2V-1.5Mo- 0.5Zr-0.3Si alloy. The unit of the special basket-weave structure is a lamellas clusters, which consist of lamellar primary ot (otp), crab-like structures at the edges of otp and lamellar secondary a (as) on both sides of otp. As the units of basket-weave structures, the width of the clusters is much larger than that of a lamellas in as-deposited alloy. The formation temperature and process of the special basket-weave structure are studied, and the room temperature properties are tested and compared with the as-deposited alloy. The results show that the formation of the special basket-weave structure finishes within about 30 s and crab-like structures form earlier than lamellar as. The yield strength of the alloy is decreased by about 75 MPa compared to that of the as-deposited alloy. Besides, the proof-ultimate strength difference of the alloy is two times higher than that of the as-deposited alloy with about 34% improvement for the impact toughness. It is because ot colony size shows a positive correlation to the width of the unit forming basket-weave structure. The enhancement in proof-ultimate strengthdifference could significantly improve the toughness of the alloy, and thus effectively increase the safety of the alloy.

关键词： Titanium alloy Basket-weave structure Formation process a colony size Yield strength

Simulation,experimental evaluation and performance improvement of a cone dielectric elastomer actuator

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第9期10卷 1296-1304页

作者： hua-ming wang Jing-ying ZHU Ke-bei YE Jiangsu Key Laboratory of Precision and Micro-manufacturing Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

Dielectric elastomer actuators (DEAs) are an emerging class of polymer actuation devices and have extensive application prospect in the field of robotics because of their light weight, high efficiency and large deformation. A cone DEA is manufactured and its working principle is analyzed. To obtain the deformation of elastomer and movement of DEA in advance, a finite element method (FEM) simulation is performed first. According to the working principle, two working equilibrium points of DEA, corresponding to the displacements of DEA with voltage off and on, are obtained and validated by experiments, thus work output in a workcycle is computed. Experiments show that the actuator can respond quickly when voltage is applied and can return to its original position rapidly when voltage is released. Simulation results agree well with experimental ones and the feasibility of DEA simulation is proved, and causes for the small difference between them in displacement output are analyzed. The performance of the actuator is improved from the aspects of both displacement and force output. A diamond four-bar linkage mechanism is used as the preload part and a displacement output of 17 mm is obtained. The force output of one actuating unit is about 1.77 N, so three actuating units are assembled in parallel and the force output is heightened to as high as 5.07 N.

关键词： Dielectric elastomer (DE) Actuator Simulation Performance improvement

High-cycle fatigue crack initiation and propagation in laser melting deposited TC18 titanium alloy

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International Journal of Minerals,Metallurgy and Materials 2013年第7期20卷 665-670页

作者： Yang wang Shu-quan Zhang Xiang-jun Tian hua-ming wang Laboratory of Laser Materials Processing and Manufacturing School of Materials Science and Engineering Beihang University

This article examines fatigue crack nucleation and propagation in laser deposited TC18 titanium alloy. The Widmanstatten structure was obtained by double-annealing treatment,. High-cycle fatigue （HCF） tests were conducted at room temperature with the stress ratio of 0.1 and the notch concentration factor Kt = 1. Fatigue cracks initiated preferentially at micropores, which had great effect on the HCF properties. The effect decreased with the decrease of pore size and the increase of distance from the pore location to the specimen surface. The crack initiation region was characterized by the cleavage facets of a lamella and the tearing of β matrix. The soft a precipitated-free zone formed along grain boundaries accelerated the crack propagation. Subsurface observation indicated that the crack preferred to propagate along the grain boundary α or border of a lamella or vertical to a lamella.

关键词： titanium alloys fatigue crack initiation crack propagation laser melting deposition