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Near-resonance tidal evolution of the Earth-Moon system influenced by orbital-scale climate change

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Research in Astronomy and Astrophysics 2019年第9期19卷 3-12页

作者： Nan Wang Zhi-guo he Ocean College Zhejiang University

We build a conceptual coupled model of the climate and tidal evolution of the Earth-Moon system to find the influence of the former on the latter. An energy balance model is applied to calculate steady-state temperature field from the mean annual insolation as a function of varying astronomical parameters. A harmonic oscillator model is applied to integrate the lunar orbit and Earth’s rotation with the tidal torque dependent on the dominant natural frequency of ocean. An ocean geometry acts as a bridge between temperature and oceanic frequency. On assumptions of a fixed hemispherical continent and an equatorial circular lunar orbit, considering only the 41 kyr periodicity of Earth’s obliquity ε and the M2 tide, simulations are performed near tidal resonance for 106 yr. It is verified that the climate can influence the tidal evolution via ocean. Compared with the tidal evolution with constant ε, that with varying ε is slowed down;the EarthMoon distance oscillates in phase with ε before the resonance maximum but exactly out of phase after that;the displacement of the oscillation is in positive correlation with the difference between oceanic frequency and tidal frequency.

关键词： Moon planets and satellites:dynamical evolution and stability planets and satellites:oceans

Lifting of Outer Actions of Groups

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Acta Mathematica Sinica,English Series 2010年第9期26卷 1693-1700页

作者： Fang ZHOU he guo LIU Department of Mathematics Taiyuan Normal University Taiyuan 030012 P. R. China Department of Mathematics Hubei University Wuhan 430062 P. R. China

Let G and N be arbitrary groups. In this paper, we construct an associated group extension εx of N/Z（N） by G for any group homomorphism X ： G → Out N, and prove that X can be lifted to a group action, that is, a group homomorphism from G to Aut N, if and only if the extension εx splits. Furthermore we obtain an explicit description for all such lifting homomorphisms and the number of its conjugacy classes, and give an application of the lifting technique of outer actions to the theory of group extensions.

关键词： Outer action group extension lifting

Polycyclic Groups Admitting a Regular Automorphism of Order Four

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Acta Mathematica Sinica,English Series 2017年第4期33卷 565-570页

作者： Tao XU he guo LIU Department of Science Hebei University of Engineering Handan 056038 P. R. China Department of Mathematics Hubei University Wuhan 430062 P. R. China

Let G be a polycyclic group and α a regular automorphism of order four of G. If the map φ: G→ G defined by g;= [g, α] is surjective, then the second derived group of G is contained in the centre of G. Abandoning t... 详细信息

关键词： Polycyclic group regular automorphism residually finite

KINETIC STUDY ON FORMATION OF BULK GLASS STATE Zr_52.5Ni_14.6Al₁₀Cu_17.9Ti₅ ALLOY

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中国有色金属学会会刊：英文版 1999年第2期9卷 69-73页

作者： he, guo Bian, Zhan Chen, guoliang Univ of Science and Technology Beijing Beijing China

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关键词： Zrbased glass state alloybulk glass state alloymelt injectioncritical cooling rate

The Isomorphism Problem of Normalized Unit Groups of Group Algebras of a Class of Finite 2-groups

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Acta Mathematica Sinica,English Series 2023年第11期39卷 2275-2282页

作者： Yu Lei WANG he guo LIU Department of Mathematics He’nan University of TechnologyZhengzhou 450001P.R.China Department of Mathematics Hainan UniversityHaikou 570228P.R.China

Let p be a prime and F_p be a finite field of p *** F_(pG)denote the group algebra of the finite p-group G over the field F_(p)and V(F_(pG))denote the group of normalized units in F_(pG).Suppose that G and H are finite p-groups given by a central extension of the form 1→Z_(p)^(m)→G→Z_(p)×···×Z_(p)→1 and G'≌Z_(p),m≥*** V(F_(p)G)≌V(F_(p)H)if and only if G≌*** and Bovdi only solved the isomorphism problem when p is *** this paper,the case p=2 is determined.

关键词： isomorphism problem normalized unit Frattini subgroup finite 2-group

Automorphisms of a Class of Finite p-groups with a Cyclic Derived Subgroup

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Acta Mathematica Sinica,English Series 2021年第6期37卷 926-940页

作者： Yu Lei WANG he guo LIU Department of Mathematics He’nan University of TechnologyZhengzhou 450001P.R.China Department of Mathematics Hubei UniversityWuhan 430062P.R.China

Let p be an odd prime,and let k be a nonzero nature *** that nonabelian group G is a central extension as follows1→G’→G→Z_(pK)×…×Z_(pK),where G’≌Zpk,andζG/G’is a,direct factor of G/G’.Then G is a central product of an extraspecial pkgroup E andζ***|E|=p(2n+1)k and|ζG|=p(m+1)*** that the exponents of E andζG are pk+l and pk+r,respectively,where 0≤l,r≤*** AutG’G be the normal subgroup of Aut G consisting of all elements of Aut G which act trivially on the derived subgroup G’,let AutG/ζG,ζG G be the normal subgroup of Aut G consisting of all central automorphisms of G which also act trivially on the centerζG and let AutG/ζG,ζG/G’G be the normal subgroup of Aut G consisting of all central automorphisms of G which also act trivially onζG/G’.Then(ⅰ)The group extension 1→Aut G’→Aut G→Aut G’→1 is split.(ⅱ)AutG’G/AutG/ζG,ζG G≌G1×G2,where Sp(2n-2,Zpk)■H≤G1≤Sp(2n,Zpk),H is an extraspecial pk-group of order p(2n-1)k and(GL(m-1,Zpk)■Zpk(m-1)■Zpk(m)≤G2≤GL(m,Zpk)■Zpk(m).In particular,G1=Sp(2n-2,Zpk)■H if and only if l=k and r=0;G1=Sp(2n,Zpx)if and only if l≤r;G2=(GL(m-1,Zpk)■Zpk(m-1)■Zpk(m)if and only if r=k;G2=GL(m,Zpk)■Zpk((m))if and only if r=0.(ⅲ)AutG’G/Aut G/ζG,ζG/G’G≌G1×G3,where G1 is defined in(ⅱ);GL(ml,Zpk)■Zpk(m-1)≤G3≤GL(n,Zpk).In particular,G3=GL(m-1,Zpk)■Zpk(m-1)if and only if r=k;G3=GL(m,Zpk)if and only if r=0.(ⅳ)AntG/ζG,ζG/G’G≌AutG/ζG,ζG/G’G■Zpk(m),If m=0,then AntG/ζG,ζG/G’G=Inn G≌Zpk(2n);If m>0,then AntG/ζG,ζG/G’G≌Zpk(2nm)×Zpk-r(2n),and AutG/ζG,ζG G/Inn G≌Zpk((2n(m-1))×Zpk-r(2n).

关键词： Automorphism p-group cyclic derived subgroup symplectic group

Mechanical Properties,Damage and Fracture Mechanisms of Bulk Metallic Glass Materials

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Journal of Materials Science & Technology 2007年第6期23卷 I0003-I0006,747-767页

作者： Zhefeng ZHANG Fufa WU guo he Eckert Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China School of Materials Science and Engineering Shanghai Jiaotong University Shanghai 200030 China IFW Dresden Institute for Complex Materials P.O. Box 270116 D-01171 Dresden Germany TU Dresden Institute for Materials Science D-01062 Dresden Germany

The deformation, damage, fracture, plasticity and melting phenomenon induced by shear fracture were investigated and summarized for Zr-, Cu-, Ti- and Mg-based bulk metallic glasses （BMGs） and their composites. The shear fracture angles of these BMG materials often display obvious differences under compression and tension, and follow either the Mohr-Coulomb criterion or the unified tensile fracture criterion. The compressive plasticity of the composites is always higher than the tensile plasticity, leading to a significant inconsistency. The enhanced plasticity of BMG composites containing ductile dendrites compared to monolithic glasses strongly depends on the details of the microstructure of the composites. A deformation and damage mechanism of pseudo-plasticity, related to local cracking, is proposed to explain the inconsistency of plastic deformation under tension and compression. Besides, significant melting on the shear fracture surfaces was observed. It is suggested that melting is a common phenomenon in these materials with high strength and high elastic energy, as it is typical for BMGs and their composites failing under shear fracture. The melting mechanism can be explained by a combined effect of a significant temperature rise in the shear bands and the instantaneous release of the large amount of elastic energy stored in the material.

关键词： Bulk metallic glasses (BMGs) criterion Plastic deformation Mechanical properties Shear fracture Failure Melting phenomenon

A constrained particle dynamics for continuum-particle hybrid method in micro- and nano-fluidics

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Acta Mechanica Sinica 2006年第6期22卷 503-508页

作者： Jia Cui guo Wei he Dewei Qi LNM Institute of Mechanics Chinese Academy of SciencesBeijing 100080 China Department of Paper and Chemical Engineering Western Michigan University Kalamazoo MI 49008 USA

A hybrid method of continuum and particle dynamics is developed for micro- and nano-fluidics, where fluids are described by a molecular dynamics （MD） in one domain and by the Navier-Stokes （NS） equations in another domain. In order to ensure the continuity of momentum flux, the continuum and molecular dynamics in the overlap domain are coupled through a constrained particle dynamics. The constrained particle dynamics is constructed with a virtual damping force and a virtual added mass force. The sudden-start Couette flows with either non-slip or slip boundary condition are used to test the hybrid method. It is shown that the results obtained are quantitatively in agreement with the analytical solutions under the non-slip boundary conditions and the full MD simulations under the slip bound- ary conditions.

关键词： Hybrid method Molecular dynamicsimulation Navier-Stokes equation Microfluidics

A review on conventional and nonconventional machining of SiC particle-reinforced aluminium matrix composites

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Advances in Manufacturing 2020年第3期8卷 279-315页

作者： Ji-Peng Chen Lin Gu guo-Jian he School of Mechanical and Electronic Engineering Nanjing Forestry UniversityNanjing 210037People’s Republic of China Department of Mechanical Engineering Polytechnic University of MilanPiazza Leonardo da Vinci 32Milan 20133Italy State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240People’s Republic of China

Among the various types of metal matrix composites,SiC particle-reinforced aluminum matrix composites(SiCp/Al)are finding increasing applications in many industrial fields such as aerospace,automotive,and ***,SiCp/Al composites are considered as difficult-to-cut materials due to the hard ceramic reinforcement,which causes severe machinability degradation by increasing cutting tool wear,cutting force,*** improve the machinability of SiCp/Al composites,many techniques including conventional and nonconventional machining processes have been *** purpose of this study is to evaluate the machining performance of SiCp/Al composites using conventional machining,i.e.,turning,milling,drilling,and grinding,and using nonconventional machining,namely electrical discharge machining(EDM),powder mixed EDM,wire EDM,electrochemical machining,and newly developed high-efficiency machining technologies,e.g.,blasting erosion arc *** research not only presents an overview of the machining aspects of SiCp/Al composites using various processing technologies but also establishes optimization parameters as reference of industry applications.

关键词： SiCp/Al Machining Conventional Wear mechanism Nonconventional Performance