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A FAMILY OF DIFFERENCE SCHEMES WITH FOURNEAR-CONSERVED QUANTITIES FOR THE KdV EQUATION

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Journal of Computational Mathematics 1998年第2期16卷 129-140页

作者： Han, z Shen, LJ No Jiaotong Univ Dept Comp Sci & Technol Beijing 100044 Peoples R China Inst Appl Phys & Computat Math Beijing 100088 Peoples R China

We construct and analyze a family of semi-discretized difference schemes with two parameters for the Korteweg-de Vries (KdV) equation. The scheme possesses the first four near-conserved quantities for periodic boundary conditions. The existence and the convergence of its global solution in Sobolev space L-infinity(0,T;H-3) are proved and the scheme is also stable about initial values. Furthermore, the scheme conserves exactly the first two conserved quantities in the special case.

关键词： convergence difference scheme KdV equation conserved quantity

Deformation behaviors of Cu bicrystals with an inclined twin boundary at multiple scales

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Journal of Materials Science & Technology 2017年第7期33卷 698-702页

作者： L.L.Li z.J.zhang P.zhang J.Tan J.B.yang z.F.zhang Shenyaag National Laboratory for Materials Science lastitute of Metal Research Chinese Academy of Sciences Shenyaag 110016 China

Cu bicrystals of different sizes with a sole twin boundary（TB） inclined at 45？with respect to the loading direction were deformed under unidirectional and cyclic loading, respectively. It is found that the slip bands（SBs） parallel to the TB can be activated near the TB at all scales without obeying the Schmid＇s *** is concerned with the local stress enhancement in the macroscale while it is more closely related to the scarce dislocation sources in the microscale. Moreover, a wedge-shaped zone formed near the TB in the microscale ascribed to the limited specimen size.

关键词： Bicrystal Micropillar Twin boundary Schmid factors Size effect

Effects of Biomimetic Surface Designs on Furrow Opener Performance

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Journal of Bionic Engineering 2009年第3期6卷 280-289页

作者： Ballel.z.Moayad Department of Agricultural Engineering University of Kordofan

The effects of biomimetic designs of tine furrow opener surface on equivalent pressure and pressure in the direction of motion on opener surface against soil were studied by finite element method (FEM) simulation and the effects of these designs on tool force and power requirements were examined *** structures of the cuticle surfaces of dung beetle (Copris ochus Motschulsky) were examined by *** structures of the cuticle surfaces and Ultra High Mo- lecular Weight Polyethylene (UHMWPE) material were modeled on surface of tine furrow opener as biomimetic *** furrow openers were analyzed in ANSYS program (a FEM simulation software).The biomimetic furrow opener surfaces with UHMWPE structures were found to have lower equivalent pressure and pressure in the direction of motion as compared to the conventional surface and to the biomimetic surfaces with textured steel-35 *** was found that the tool force and power were increased with the cutting depth and operating speed and the biomimetic furrow opener with UHMWPE tubular section ridges showed the lowest resistance and power requirement against soil..

关键词： furruw opener UHMWPE biomimetic surface design tillage resistance finite element analysis

Correlation Between Local Atomic Symmetry and Mechanical Properties in Metallic Glasses

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Journal of Materials Science & Technology 2014年第6期30卷 551-559页

作者： M.z.Li Department of Physics Renmin University of China Beijing Key Laboratory of Opto-Electronic Functional Materials & Micro-nano Devices Renmin University of China

The local atomic symmetry was investigated and discussed for understanding mechanical, vibrational and dynamical properties in metallic glasses. Local five-fold symmetry was defined based on the ratio of pentagons to the total number of faces in a Voronoi cluster analyzed by Voronoi tessellation method. It is found that the plastic deformation prefer to be initiated in the regions with less degree of local five-fold symmetry （LFFS） and propagate gradually toward the region with more degree of LFFS. On the other hand, the local structures having less degree of LFFS contribute more to the soft low-frequency modes, and thus the so-called boson peak, while those with more degree of LFFS participate more in moderate- and high- frequency modes in metallic glasses. The relationship between local atomic symmetry and structural heterogeneity, mechanical heterogeneity, and glass transition was also discussed. It is shown that local atomic symmetry could be a general structural indicator in metallic liquids and glasses for better understanding the structure-property relationship in amorphous alloys.

关键词： Metallic glasses Atomic symmetry Deformation Molecular dynamics

STRESS ANALYSIS OF THE APERTURE IN COMPOUND PIPELINE BY FEM

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Acta Metallurgica Sinica(English Letters) 2007年第5期20卷 385-390页

作者： J.G. yang H.Y. Fang C.L. Fan z. Luo X.z. Hou State Key Laboratory of Advanced Welding Production Technology Harbin Institute of Technology Harbin 150001 China School of Material Science and Engineering Tianjin University Tianjin 300072 China Daqing Oil-Ghem-Wdding Institute Daqing 163712 China

There is a cyclical aperture at a certain part of the fiberglass reinforced plastic compound pipeline with a stainless steel pipe as a liner, which becomes the weakness of the conduit. The field of stress and strain of the aperture was investigated using the nonliner finite element code Marc. The results of the finite element analysis showed that there were concentrations of stress and strain in the layer of stainless steel at the part of the pipeline where the aperture existed. The method to solve these problems was also discussed.

关键词： compound pipeline stress software Marc

Comparison Study of Constitutive Models for Overconsolidated Clays

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Acta Mechanica Solida Sinica 2020年第1期33卷 98-120页

作者： z.Wan Y.P.Yao z.W.Gao Research Institute of Base and Foundation China Academy of Building ResearchBeijing 100013China School of Transportation Science and Engineering Beihang UniversityBeijing 100091China School of Engineering University of GlasgowGlasgow G128QQUK

Widely distributed in natural deposits,the overconsolidated(OC)clays have attracted extensive experimental investigations on their mechanical behaviors,especially in the 1960s and *** on these results,numerous constitutive models have also been *** models generally fall into two categories:one based on the classical plasticity theory and the other the bounding surface(BS)plasticity theory,with the latter being more popular and *** BS concept and the subloading surface(SS)concept are the two major BS plasticity *** features of these two concepts and the representative models based on them are introduced,*** unified hardening(UH)model for OC clays is also based on the BS plasticity theory but distinguishes itself from other models by the integration of the reference yield surface,unified hardening parameter,potential failure stress ratio,arid transformed stress *** is made to the Hvorslev envelop employed in the UH model to improve its capability of describing the behaviors of clays with extremely high overconsolidation ratio in this *** comparison among the BS model,SS model,and UH model is *** shows that all these three models can characterize the fundamental behaviors of OC clays,such as the stress dilatancy,strain softening and attainment of the critical *** UH model with the revised Hvorslev envelop has the fewest parameters which are identical to those of the modified Cam-Clay model.

关键词： Clay Overconsolidation Critical state Bounding surface Subloading surface Unified hardening model

STRUCTURAL DETERMINATION OF TITANIUM-OXIDE NANOPARTICLES BY X-RAY ABSORPTION SPECTROSCOPY

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Acta Metallurgica Sinica(English Letters) 2002年第1期15卷 53-57页

作者： z.Y. Wu J. zhang K. Ibrahim M.I. Abbas G. Li Y. Tao T.D. Hu F.Q. Liu H.J. Qian Y.N. Xie Q.H. zhang L. Gao z.z. Chen Beijing Synchrotron Radiat. Facility Inst. of High Energy Phys. Chinese Acad. of Sci. Beijing 100039 China

As a potential application of titanium-oxide nanoparticles, it is extremely important to investigate a detailed picture of the surface and interior structural properties of nanocrystalline materials, such as rutile and anatase with diameters 7.0 and 4.5nm, respectively. X-ray absorption spectroscopy has been used to identify the local Ti environment and related electronic structure. We combine the experimental results at the Ti edge in both bulk and nano-crystals to determine the lattice distortion in terms of differently characteristic preedge features and the variation in the multiple-scattering region of X-ray absorption near-edge structure (XANES) spectra. The relationship between the transition peaks and the surface-to volume ratio is also discussed.

关键词： X-ray absorption near edge structure nano particle transition metal oxide

Pyroelectric spectrum in Pb(zr,Sn,Ti)O3 antiferroelectric- ferroelectric ceramics

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Chinese Science Bulletin 2000年第13期45卷 1169-1172页

作者： Feng, YJ Xu, z yang, TQ Yao, X Xian Jiao Tong Univ Elect Mat Res Lab Xian 710049 Peoples R China

The pyroelectric effect of phase transition induced with temperature in Nb-modified Pb(zr,Sn,Ti)O3 antiferroelectric-ferroelectric ceramics is studied. Experimental results reveal that the phase transitions are accompanied with marked pyroelectric peaks, there exists the close relation between the type of phase transition and the shape of pyroelectric peak. Because of the variations of phase transition, various pyroelectric spectra result. The pyroelectric spectrum can display the polarization effect and some inferior phase transitions with temperature variations, such as antiferroelectric AFEA-AFEB or ferroelectric FEL-FEH transition, which are not detected by the conventional dielectric measurement.

关键词： Pb(zr Sn Ti)O3 ceramics pyroelectric spectrum temperature-induced phase transition.

Physical and Kinematical Characteristics of Wolf–Rayet Central Stars and their Host Planetary Nebulae

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Research in Astronomy and Astrophysics 2023年第9期23卷 219-240页

作者： z.Awad A.Ali Department of Astronomy Space Science and MeteorologyFaculty of ScienceCairo University12613 Giza

We address the physical and kinematical properties of Wolf–Rayet[WR]central stars(CSs)and their host planetary nebulae(PNe).The studied sample comprises all[WR]CSs that are currently *** analysis is based on recent observations of the parallax,proper motion,and color index of[WR]CSs from the Gaia space mission’s early third release(eDR3)catalog,as well as common nebular *** results revealed an evolutionary sequence,in terms of decreasing Teff,from the early hot[WO 1]to the late cold[WC 12]*** evolutionary sequence extends beyond[WR]CS temperature and luminosity to additional CS and nebular *** statistical analysis shows that the mean final stellar mass and evolutionary age of the[WR]CS sample are 0.595±0.13M⊙and 9449±2437 yr,respectively,with a mean nebular dynamical age of 7270±1380 *** addition,we recognize that the color of the majority(∼85%)of[WR]CSs tends to be red rather than their genuine blue *** analysis indicates that two-thirds of the apparent red color of most[WR]s is attributed to the interstellar extinction whereas the other one-third is due to the PN self-extinction effect.

关键词： Wolf-Rayet-(ISM )planetary nebulae general-ISM kinematics and dynamics