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CONVERGENCE OF VORTEX METHODS FOR 3-D EULER EQUATIONS

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Journal of Computational Mathematics 2000年第3期18卷 239-250页

作者： Jia-fu Lin (Institute of System Science, academy of Mathematics and System sciences, chinese academy of sciences, beijing, 100080, china School of Mathematical sciences, Peking University, beijing 100871, china) 中科院系统科学所北京 100080

Presents a study on the convergence of vortex methods for the three-dimensional Euler equations in bounded domains. Related studies on the convergence of vortex methods; Formulation of vortex methods; Convergence for ... 详细信息

关键词： Euler equations vortex methods convergence initial-boundary value problem

Scheme construction with numerical flux residual correction (NFRC) and group velocity control (GVC)

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Progress in Natural Science:Materials International 2006年第12期16卷 1252-1259页

作者： MA Yanwen **and fu Dexun(LNM, Institute of Mechanics, chinese academy of sciences, beijing 100080, china) [a]LNM Institute of Mechanics Chinese Academy of Sciences Beijing China

For simulating multi-scale complex flow fields like turbulent flows, the high order accurate schemes are preferred. In this paper, a scheme construction with numerical flux residual correction (NFRC) is presented. Any order accurate difference approximation can be obtained with the NFRC. To improve the resolution of the shock, the constructed schemes are modified with group velocity control (GVC) and weighted group velocity control (WGVC). The method of scheme construction is simple, and it is used to solve practical problems.

关键词： high order accurate scheme group velocity control high resolution of the shock.

SYNTHESIS AND POLYMERIZATION OF TRI(2-PYRIDYL)METHYL METHACRYLATE

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chinese Journal of Polymer Science 1999年第3期17卷 295-298页

作者： Chuan-fu Chen Yong-hong Yang fu Xi Institute of Chemistry, chinese academy of sciences, beijing 100080, china chinese Acad Sci Inst Chem Beijing 100080 Peoples R China

A novel methacrylate monomer with bulky side group, tri(2-pyridyl)methyl methacrylate (Tr2PyMA), was synthesized and polymerized. The polymer obtained by radical polymerization exhibits high isotactic tacticity.

关键词： optical activity tri(2-pyridyl)methyl methacrylate

On Stability and Trajectory Boundedness in Mean-square Sense for ARMA Processes

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Acta Mathematicae Applicatae Sinica 2003年第4期19卷 573-580页

作者： Han-fu Chenacademy of Mathematics and Systems Science, chinese academy of sciences, beijing 100080, china academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China

For the multidimensional ARMA system A(z)y k = C(z)w k it is shown that stability (det A(z) = 0, z : |z| 1) of A(z) is equivalent to the trajectory boundedness in the mean square sense (MSS) which, as a rule, is a consequence of a successful stochastic adaptive control leading the closed-loop of an ARMAX system to a steady state ARMA system. In comparison with existing results the stability condition imposed on C(z) is no longer needed. The only structural requirement on the system is that det A(z) and det C(z) have no unstable common factor.

关键词： ARMA stability boundedness in MSS equivalence

Numerical simulation of Richtmyer-Meshkov instability

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Science china Mathematics 2004年第z1期47卷 234-244页

作者： fu Dexun, MA Yanwen, ZHANG Linbo & TIAN BaolinState Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, chinese academy of sciences, beijing 100080, china State Key Laboratory of Scientific and Engineering Computing, Institute of Computational Mathematics, chinese academy of sciences, beijing 100080, china 1. State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences 100080 Beijing China2. State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics Chinese Academy of Sciences 100080 Beijing China

The compressible Navier-Stokes equations discretized with a fourth order accurate compact finite difference scheme with group velocity control are used to simulate the Richtmyer-Meshkov (R-M) instability problem produced by cylindrical shock-cylindrical material interface with shock Mach number Ms=1.2 and density ratio 1:20 (interior density/outer density). Effect of shock refraction, reflection, interaction of the reflected shock with the material interface, and effect of initial perturbation modes on R-M instability are investigated numerically. It is noted that the shock refraction is a main physical mechanism of the initial phase changing of the material surface. The multiple interactions of the reflected shock from the origin with the interface and the R-M instability near the material interface are the reason for formation of the spike-bubble structures. Different viscosities lead to different spike-bubble structure characteristics. The vortex pairing phenomenon is found in the initial double mode simulation. The mode interaction is the main factor of small structures production near the interface.

关键词： R-M instability, direct numerical simulation, shock-interface interaction.

Control of Melt Structures on Cu-Au Mineralization in Basic-Ultrabasic Complexes of Northern china

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Acta Geologica Sinica(English Edition) 2000年第4期74卷 786-794页

作者： YUAN Wanming Institute of High Energy physics, chinese academy of sciences, beijing 100080and MO Xuanxue china University of Geoscienses, beijing 100083 Institute of High Energy physics Chinese Academy of Sciences Beijing 100080 china University of Geoscienses Beijing 100083 [?]3Yuan Wanming Born in April 1956 graduated from Hebei College of Geology in 1982. He was once engaged in teaching in Hebei College of Geology for many years and acquired M.Sc and Ph.D degrees in petrology at china University of Geosciences (Wuhan) and china University of Geosciences (beijing) in 1989 and 1997 respectively. Dr. Yuan now works with the Institute of High Energy physics Chinese Academy of Sciences doing postdoctoral research work. His interests are mainly nuclear techniques and their applications to geology. E-mail: panm@***.

Based on systematic analyses of 72 samples of different basic-ultrabasic rocks, the present paper discusses the relationship between melt structure and Cu and Au mineralization. It is found that if the NBO/T, NBO, M2+, FeO and MgO values are relatively high and the T, M3+, Fe2O3 and CaO values are low the basic-ultrabasic melt will be favourable to Cu (Ni) mineralization, but if the former are low and the latter are high it is favourable to Au metallization. Cu ions occupy dominantly octahedra in basic-ultrabasic melt and the higher the NBO/T, NBO and M2+ values, the more the octahedra in the melt. Au element mainly takes the form of Au+ ions in basic-ultrabasic melt and the Au+ ions constitute tetrahedral sites together with Fe3+ ions. Therefore, low M2+ and high Fe3+, i.e. high oxygen fu-gacity, can promote the enrichment of Au+ ions and Au mineralization. Components NT (other than Au+), Al2O3 and SiO2 in basic-ultrabasic melt have no effect on metallogenetic species. As mentioned above, in relevant diagrams distribution areas of the characteristic values of ore-free melt and those of ore-forming melt are overlapped in different degrees, which possibly indicates that not all the magmas have mineralizing ability. It can be well distinguished whether basic-ultrabasic rocks are favourable to Cu or Au mineralization or they are just ore-free rocks by analysing integrated diagrams of the characteristic values of the magmatic melt structure.

关键词： melt structure Cu-Au mineralization basic-ultrabasic complex

MORPHOLOGICAL CHARACTERIZATION OF POLY (N-VINYLCARBAZOLE) OBTAINED WITH ASYMMETRICALLY STEREOSELECTIVE POLYMERIZATION

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chinese Journal of Polymer Science 1999年第2期17卷 159-163页

作者： Quan Su Chuan-fu Chen Yong-ming Chen fu Xi PCLCC, Institute of Chemistry, chinese academy of sciences. beijing 100080, china chinese Acad Sci Inst Chem PCLCC Beijing 100080 Peoples R China

The morphological characterizations of poly(N-vinylcarbazole)(PVCZ) obtained by asymmetrically stereoselective polymerization were studied using x-ray diffraction pattern, DSC and GPC. The results show that the PVCZs have lower crystallinities (11.0 similar to 18.6%) and lower melting heats (2.2 similar to 7.5 J/g), but the degree of crystallinities of the PVCZ samples obtained using the organic salts (acid) with chiral or stereodifferentiating ligands are higher than that using radical and general protonic initiator. It has shown that the crystallization is directly related to the packing density of the hexagonal array of the rodlike molecules formed from the helical chain.

关键词： crystal optically active poly(N-vinylcarbazole)

Difference schemes on non-uniform mesh and their application

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Progress in Natural Science:Materials International 2004年第10期14卷 8-14页

作者： MA Yanwen ,GAO Hui,fu Dexun and LI Xinliang (Laboratory of Nonlinear Mechanics,Institute of Mechanics,chinese academy of sciences,beijing100080,china) chinese Acad Sci Inst Mech Lab Nonlinear Mech Beijing 100080 Peoples R China

High order accurate schemes are needed to simulate the multi-scale complex flow fields to get fine structures in simula-tion of the complex flows with large gradient of fluid parameters near the wall,and schemes on non-uniform mesh are desirable for many CFD(computational fluid dynamics)*** construction methods of difference approximations and several difference approxima-tions on non-uniform mesh are *** accuracy of the methods and the influence of stretch ratio of the neighbor mesh increment on accuracy are *** comments on these methods are given,and comparison of the accuracy of the results obtained by schemes based on both non-uniform mesh and coordinate transformation is made,and some numerical examples with non-uniform mesh are present-ed.

关键词： scheme on non-uniform mesh high order accurate scheme compact difference approximation

OPTICALLY ACTIVE COPOLYESTERS BASED ON AXIALLY DISSYMMETRIC 1,1’-BINAPHTHALENE-2,2’-DIYL UNITS

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chinese Journal of Polymer Science 2000年第5期18卷 443-447页

作者： Chuan-fu Chen Min Ai Zhong Li Hong-wei Liu Ai-jun Gong fu Xi Institute of Chemistry, chinese academy of sciences, beijing 100080, china chinese Acad Sci Inst Chem Beijing 100080 Peoples R China

Optically active copolyesters based on axially dissymmetric 1,1'-binaphthalene-2,2'-diyl units have been preparedand characterized by specific rotation, ^(13)C-NMR and CD spectra. The results show that the rotation signs of tribasiccopolyesters or the mixture of corresponding homopolyesters obey a three dimensional quadrant pattern. The composition ofthe copolyesters was determined from ^(13)C-NMR spectra to be triad sequence distributions and corresponding with the ratioby feed.

关键词： Optical activity Copolyester 1, 1'-Binaphthalene-2,2'-diol Diethyl tartrate