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Tree-decompositions of graphs ( I )

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chinese Science Bulletin 1997年第4期42卷 277-281页

作者： shi minyonginstitute of Systems Science, chinese academy of sciences beijing 100080, china Institute of Systems Science Chinese Academy of Sciences Beijing China

IN this note all graphs are undirected, finite and simple. For a subgraph H of G, V(H), E(H), ε(H) and μ(H) denote the set of vertices, the set of edges, the number of edges in H and the number of cycles in H respectively. H[X] denotes the subgraph of H induced by X. Given two disjoint subsets X and Y of V(G), we write E_G(X, Y)={xy∈E(G)

关键词： tree-decomposition singular vertex maximal planar bipartite graph.

GENERALIZED GAUSSIAN QUADRATURE FORMULASWITH CHEBYSHEV NODES

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Journal of Computational Mathematics 1999年第2期17卷 171-178页

作者： Ying-guang shi(ICMSEC, chinese academy of sciences, beijing 100080, china) 中科院计算数学与科学工程计算所北京

Explicit expressions of the Cotes numbers of the generalized Gaussian quadrature formulas for the Chebyshev nodes (of the first kind and the second kind) and their asymptotic behavior are given.

关键词： quadrature formula Chebyshev polynomials

OPTIMAL MIXED H-P FINITE ELEMENT METHODS FOR STOKES AND NON-NEWTONIAN FLOW

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Journal of Computational Mathematics 2001年第1期19卷 67-76页

作者： Ping-bing Ming Zhong-ci shi (Institute of Computational Mathematics, chinese academy of sciences, beijing 100080, china) 中科院计算数学与工程计算数学所北京 100080

Presents an h -- p finite element methods based upon a mixed variational formulation for the three-field Stokes equations and linearized Non-Newtonian flow. Computation of the algebraic system generated from Problem H... 详细信息

关键词： mixed hp- finite element method non-Newtonian flow stabilization scaled weak B-Binequality

MATHEMATICAL ANALYSIS FOR QUADRILATERAL ROTATED Q_1 ELEMENT Ⅲ: THE EFFECT OF NUMERICAL INTEGRATION

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Journal of Computational Mathematics 2003年第3期21卷 287-294页

作者： Ping-bing Ming Zhong-ci shi (Institute of Computational Mathematics, chinese academy of sciences, beijing 100080, china) Institute of Computational Mathematics Chinese Academy of Sciences 北京 100080

This is the third part of the paper for the rotated Q1 nonconforming element on quadrilateral meshes for general second order elliptic problems. Some optimal numerical formulas are presented and analyzed. The novelty is that it includes a formula with only two sampling points which excludes even a Q1 unisolvent set. It is the optimal numerical integration formula over a quadrilateral mesh with least sampling points up to now.

关键词： Quadrilateral rotated Q1 element Numerical quadrature.

COPOLYMERIZATION OF ETHYLENE AND PROPYLENE WITH (CpCH_2CH_2CH=CH_2)_2MCl_2(M=Zr,Hf)AND Cp_2ZrCl_2 CATALYSTS

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chinese Journal of Polymer Science 2000年第2期18卷 169-175页

作者： Hui Yao shi-jing Xiao Institute of Chemistry, chinese academy of sciences, beijing 100080, china chinese Acad Sci Inst Chem Beijing 100080 Peoples R China

(CpCH_2CH_2CH = CH_2)_2MCl_2(M=Zr, Hf)/MAO and Cp_2ZrCl_2/MAO (Cp=cyclopentadienyl; MAO=methylaluminoxane) catalyst systems have been compared for ethylene copolymerization to investigate the influence of theligand and transition metal on the polymerization activity and copolymer properties. For both CH_2CH_2CH=CH_2 substitutedcatalysts the catalytic activity decreased with increasing propene concentration in the feed. The activity of the hafnocenecatalyst was 6～8 times lower than that of the analogous zirconocene catalyst, ^(13)C NMR analysis showed that the copolymerobtained using the unsubstituted catalyst Cp_2ZrCl_2 has greater incorporatien of propene than those produced byCH_2CH_2CH=CH_2 substituted Zr and Hf catalysts. The melting point, crystallinity and the viscosity-average molecularweight of the copolymer decreased with an increase of propenc concentration in the feed. Both CH_2CH_2CH= CH_2 substitutedZr and Hf catalysts exhibit little or no difference in the melting point and crystallinity of the produced copolymers. However,there are significant differences between the two zirconocene catalysts. The copolymer produced by Cp_2ZrCl_2 catalyst havemuch lower T_m and X_c than those obtained with the (CpCH_2CH_2CH=CH_2)_2ZrCl_2 catalyst. The density and molecular weightof the copolymer decreased in the order: (CpCH_2CH_2CH=CH_2)_2HfCl_2>(CpCH_2CH_2CH=CH_2)_2ZrCl_2>Cp_2ZrCl_2. The kineticbehavior of copolymerizaton with Hf catalyst was found to be different from that with Zr catalyst.

关键词： Metallocene catalyst Ethylene/propylene copolymerization Methylaluminoxane

SURFACE MODIFICATION OF POLYPROPYLENE MICROFIBRE BY PLASMA-INDUCED VAPOR GRAFTING WITH ACRYLIC ACID

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chinese Journal of Polymer Science 1999年第3期17卷 221-229页

作者： Hong-jun Liang Qiu-shi Sun Xiao-huai Hou Institute of Chemistry, chinese academy of sciences, beijing, 100080, china chinese Acad Sci Inst Chem Beijing 100080 Peoples R China

The hydrophilicity, dyeing and antistatic ability of polypropylene microfibre (PPMF) were improved by plasma-induced vapor grafting with acrylic acid. The effects of plasma discharge time, power, liquid phase acrylic acid temperature and environmental temperature on grafting yield were investigated. The existence of grafted polyacrylic acid (PAA) was verified by ESCA and ATR FT-IR. The morphology of grafted PAA was directly observed by SEM. The wicking test shows that the hydrophilicity of modified PPMF is greatly enhanced. The dyeability test of modified PPMF was carried out using Dispersion Yellow. It was found that the dye uptake ratio is linear to the weight percent of grafting. The antistatic ability was indicated by specific resistance. The specific resistance of modified PPMF was reduced to 10(6) similar to 10(7) Ohm . cm, thus the antistatic ability was considerably improved.

关键词： polypropylene microfibre (PPMF) plasma-induced grafting dyeability antistatic ability hydrophilicity contact angle

MgCl_2·6H_2O-BASED ZIRCONOCENE CATALYST FOR ETHYLENE POLYERIZATION

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chinese Journal of Polymer Science 1999年第2期17卷 185-188页

作者： shi-jing Xiao Hui Yao Ke-quan Peng Institute of Chemistry, chinese academy of sciences, beijing 100080, china Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China

Several supported zirconocene catalysts were prepared by using MgCl_2·6H_2O as a precursor forproducing an active support. Such catalysts combined with methylaluminoxane (MAO) obtained by reactingMgCl_2·6H_2O with AlMe_3 show good activity for ethylene polymerization similar to that of anhydrousMgCl_2 supported zirconocene catalyst.

关键词： MgCl_2.6H_2O, Supported zirconocene catalyst Ethylene polymerization

SYNTHESIS OF NOVEL SOLUBLE AROMATIC POLYPYROMELLITIMIDE CONTAINING ORDERED 1,2,4-TRIAZINE IN THE MAIN CHAIN

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chinese Journal of Polymer Science 2002年第3期20卷 219-224页

作者： Xiao-bing Yi Guo-shi Wu Feng-cai Lu Department of Chemistry Tsinghua University, beijing 100084 china Institute of Chemistry chinese academy of sciences, beijing 100080, china Tsing Hua Univ Dept Chem Beijing 100084 Peoples R China chinese Acad Sci Inst Chem Beijing 100080 Peoples R China

A new heat-resistant, soluble polymer, poly(phenyl-1,2,4-triazine imide), has been prepared via a two-step method of polycondensation of N,N'-bis(4-benzil)pyromellitimide and terephthalamidrazone in cresol, followed by curing at higher temperature. The rigid 1,2,4-triazine group increases the solubility of the polyimide so that the polymer is soluble in cresol, N-methyl-2-pyrrolidone (NMP), trifluoroacetic acid and concentrated sulfuric acid, etc. Thermogravimetric analysis (TGA) indicates that this novel polyimide has good thermal stability with a high decomposition temperature of 447degreesC in air and of 423 degreesC in N-2, It has a tensile strength of 107.4 MI'a with an elongation at break of around 7.6%.

关键词： polyimides N,N '-bis(4-benzil)pyromellitimide rigid-rod group 1,2,4-triazine

Experimental Studies on Combustion Characteristics of Mixed Municipal Solid Waste

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Journal of Thermal Science 2003年第4期12卷 367-370页

作者： Fan Jiang Zhonggang Pan shi Liu Haigang WangInstitute of Engineering Thermophysics, chinese academy of sciences, beijing 100080, china Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing China

In our country, municipal solid wastes (MSW) are always burnt in their original forms and only a few pretreatments are taken. Therefore it is vital to study the combustion characteristics of mixed waste. In this paper, thermogravimetric analysis and a lab scale fluidized bed facility were used as experimental means. The data in two different experimental systems were introduced and compared. It took MSW 3-3.5 min to burn out in FB, but in thermogravimetric analyzer, the time is 20-25 min. It can be concluded that, in general, the behavior of a mixture of waste in TGA can be expressed by simple combination of individual components of the waste mixtures. Only minor deviations from the rule were observed. Yet, in Fluidized Bed, it was found that, for some mixtures, there was interference among the components during fluidized bed combustion.

关键词： municipal solid waste thermogravimetric analysis fluidized bed combustion characteristics.