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RANDOM COPOLYMER OF PROPYLENE OXIDE AND ETHYLENE OXIDE PREPARED BY DOUBLE METAL CYANIDE COMPLEX CATALYST

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Chinese Journal of Polymer Science 2002年第5期20卷 453-459页

作者： Yi-jun Huang Guo-rong Qi Guan-xi Chen Department of Polymer Science and Engineering, zhejiang university hangzhou 310027,china zhejiang Univ Dept Polymer Sci & Engn Hangzhou 310027 Peoples R China

Copolymerization of propylene oxide (PO) and ethylene oxide (EO) using double metal cyanide (DMC) complex as the catalyst was carried out. The structure of random copolymers was confirmed by C-13-NMR and IR spectra. H-1-NMR analysis shows that the EO content in the copolymer is the same as that in the initial monomer feed. Moderate molecular weight copolymers with various EO content were obtained and their values of molecular weight distribution (MWD) fell in the range of 1.21-1.55. It was found that the molecular weight of copolymers is controlled by the mass ratio of EO+PO to initiator moles used, The reaction rate as well as polymer yield decrease with increasing EO content in the feed composition.

关键词： propylene oxide ethylene oxide double metal cyanide complex

Hodograph computation and bound estimation for rational B-spline curves

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Progress in Natural Science:Materials International 2007年第8期17卷 988-992页

作者： Xu Huixia~(1,2) Wang Guojin~(1,2**) (1.Institute of Computer Images and Graphics,zhejiang university,hangzhou 310027,china 2.State Key Laboratory of CAD&CG,zhejiang university,hangzhou 310027,china) [a]Institute of Computer Images and Graphics Zhejiang University Hangzhou China [b]State Key Laboratory of CAD&CG Zhejiang University Hangzhou China

It is necessary to compute the derivative end estimate the bound of rational B-spline curves in design system,which has not been studied to *** improve the function of computer aided design (CAD) system,end to enhance the efficiency of different algo- rithms of rational B-spline curves,the representation of scaled hodograph and bound of derivative magnitude of uniform planar rational B- spline curves are derived by applying Dir function,which indicates the direction of Cartesian vector between homogeneous points,discrete B-spline theory end the formula of translating the product into a summation of B-spline *** an application of the result above, upper bound of parametric distance between any two points in a uniform planar rational B-spline curve is further presented.

关键词： computer aided design (CAD) rational B-spline discrete B-spline hodograph bound of derivative distance between two points

EXACT SOLUTION TO THE PROBLEM OF A HALF-PLANE CRACK IN A TRANSVERSELY ISOTROPIC PIEZOELECTRIC BODY SUBJECTED TO ANTISYMMETRIC TANGENTIAL POINT FORCES

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Acta Mechanica Solida Sinica 2001年第2期14卷 176-182页

作者： Hou Pengfei Ding Haojiang Guan Fuling (Department of Civil Engineering, zhejiang university, hangzhou 310027, china) ***

An exact and complete solution of the problem of a half-planecrack in an infinite transversely isotropic piezoelectric body ispresented. The upper and lower crack faces are assumed to be loadedantisym- metrically by a couple of tangential point forces inopposite directions. The solution is derived through a lim- itingprocedure from that of a penny-shaped crack. The expressions for theelectroelastic field are given in terms of elementary ***, the numerical results of the second and third mode stressintensity factors k_2 and k_3 of piezoelectric materials and elasticmaterials are compared in figures.

关键词： half-plane crack transversely isotropic piezoelectric body antisymmetrictangential forces

Genome organization and phylogenetic tree analysis of Garlic virus E,a new member of genus Allexivirus

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Chinese Science Bulletin 2002年第1期47卷 33-37页

作者： CHEN Jiong & CHEN JianpingCollege of Life sciences, zhejiang university, hangzhou 310029, china Virology Department, zhejiang Academy of Agricultural sciences, hangzhou 310021, china College of Life sciences Zhejiang University Hangzhou China Virology Department Zhejiang Academy of Agricultural Sciences Hangzhou China

The complete sequence of an Allexivirus iso-lated from garlic plants in Yuhang City, zhejiang Province, china had been determined. The single-strand, positive RNA genome was 8451 nucleotides in length excluding poly(A) tail. The genome organization of this virus was similar to that of the other Allexiviruses but only with 62.8%-64.8% nucleo-tide acid identities. The amino acid sequences of proteins encoded by ORFl-6 shared 67.6%-78.5%, 55.4%-66.2%, 56.7%-66.4%,40.3%-55.6%,66.3%-79.7%and 52.2%-68.8% identities with those of the others respectively. The homology range between it and the other Allexiviruses was similar to that between the other distinct species in this genus. A more comprehensive comparison using all available CP amino acid sequences showed that it shared only 63.9%-79.8% amino acids identical with the others. Therefore, it had been considered as a new member of the genus, named as garlic virus E (GarV-E). Phylogenetic analysis confirmed GarV-E as a distinct member and the correct names

关键词： genus Allexivirus garlic virus E nucleotide sequence classification.

Preparation of TiC/Ni_3Al Composites by Upward Melt Infiltration

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Journal of Materials Science & Technology 2000年第4期16卷 387-392页

作者： Yi PAN (Department of Materials Science and Engineering, zhejiang university, hangzhou 310027, china) Kewei SUN (National Engineering Research center of Solid Waste Resources Recovery, Kunming university of Science and Technology,Kunming 650093, china) Department of Materials Science and Engineering Zhejiang University Hangzhou 310027 China National Engineering Research center of Solid Waste Resources Recovery Kunming University of Science and Technology Kunming 650093 China

TiC/Ni_3Al composites have been prepared using upward infiltration method. The densification was performed by both Ni_3Al melt filling and TiC sintering during the infiltration. The dissolution of TiC in liquid Ni_3Al has been evidenced by finding Ni_3(Al,Ti)C after fast cooling in the TiC/Ni_3Al composites. The dissolution may be responsible for the infiltration and sintering. Compared with downward infiltration, the upward infiltration brought about higher strength and fracture toughness and shorter infiltration time. TiC/20 vol. pct Ni_3Al composite processed by upward infiltration had a flexural strength of 1476 MPa with a statistic Weibull modulus of 20.2 and a fracture toughness of 20.4 MPa . Better mechanical properties may be attributed to melt unidirectional movement in upward infiltration.

关键词： TiC Preparation of TiC/Ni3Al Composites by Upward Melt Infiltration Ni Al

Wake structures of two spheres in tandem arrangement at various gaps for Re=300

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Progress in Natural Science:Materials International 2005年第2期15卷 37-41页

作者： ZOU Jianfeng*, REN Anlu, DENG Jian and CHEN Wenqu(Department of Mechanics, zhejiang university, hangzhou 310027, china) Department of Mechanics Zhejiang University Hangzhou 310027 China

The virtual boundary method is extended to a 3D application and used to simulate the flow field of two spheres in tandem arrangement for a Reynolds number of 300. The wake structures and flow spectra at various gaps are investigated. The numerical results show that for small gaps (≈1.5), due to the mutual suppress between the wakes of the two spheres, the full flow field is stable and axisymmetric. As the gap is increased to 2.0, an asymmetric but stable flow is constructed through a certain bifurcation. The downstream wake structure is characterized by a double-thread vortex structure that comprises two slender parallel vortex tubes. The double-thread structure has a planar symmetry at gap 2.0. The hairpin-shape vortices are periodically shed from the downstream sphere at gap 2.5, but the planar symmetry persists. The vortex structures at gaps ranging from 3.0 to 4.0 are irregular and the flow field is undergoing a kind of 3D transition. It is up to the large gap 5.0 that the hairpin-shape structures are reconstructed behind the upstream and the downstream sphere, and the planar symmetry is resumed. All these numerical computations were performed on an SGI Origin3900 machine at the center for Engineering and Scientific Computation of zhejiang university.

关键词： virtual boundary method flow past two spheres wake structure flow spectra

P systems based multi-objective optimization algorithm

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Progress in Natural Science:Materials International 2007年第4期17卷 458-465页

作者： Huang Liang, He Xiongxiong, Wang Ning and Xie Yi ( National Laboratory of Industrial Control Technology, Institute of Advanced Process Control, zhejiang university, hangzhou 310027, china zhejiang university of Technology, hangzhou 310033, china) [a]National Laboratory of Industrial Control Technology Institute of Advanced Process Control Zhejiang University Hangzhou China [b]zhejiang university of Technology Hangzhou China

Based on P systems, this paper proposes a new multi-objective optimization algorithm (PMOA). Similar to P systems, PMOA has a cell-like structure. The structure is dynamic and its membranes merge and divide at different stages. The key rule of a membrane is the communication rule which is derived from P systems. Mutation rules are important for the algorithm, which has different ranges of mutation in different membranes. The cooperation of the two rules contributes to the diversity of the population, the conquest of the muhimodality of objective function and the convergence of algorithm. Moreover, the unique structure divides the whole population into several sub populations, which decreases the computational complexity. Almost a dozen popular algorithms are compared using several test problems. Simulation results illustrate that the PMOA has the best performance. Its solutions are closer to the true Pareto-optimal front

关键词： P systems evolutionary algorithm multi-objective optimization Pareto optimality.

An extension of Bernstein-Bezier surface over the triangular domain

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Progress in Natural Science:Materials International 2007年第3期17卷 352-357页

作者： CAO Juan and WANG Guozhao (Institute of Image Processing and Computer Graphic, Department of Mathematics, zhejiang university, hangzhou 310027, china) Institute of Image Processing and Computer Graphic Department of Mathematics Zhejiang University Hangzhou 310027 China

In this paper, a set of quasi-Bernstein polynomials of degree n with one parameter is presented, which is an extension of the Bernstein polynomials over the triangular domain. Using the presented polynomials as basis functions, we construct a class of shape adjusting surfaces defined over the triangular domain with a shape parameter, namely, quasi-B-B parametric surfaces. These surfaces share many properties with the B-B parametric surfaces. In particular, when shape parameters equal 1, they degenerate to be the B-B parametric surfaces. By changing the value of the shape parameter, we can get different surfaces under the fixed control net.

关键词： triangular domain shape parameter Bezier surfaces.

Constrained Bézier curves' best multi-degree reduction in the L2-norm

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Progress in Natural Science:Materials International 2005年第9期15卷 843-850页

作者： ZHANG Renjiang 1,2 ** and WANG Guojin1(1. Institute of Computer Images and Graphics, zhejiang university, hangzhou 310027, china 2. china Institute of Metrology, zhejiang, hangzhou 310034, china) Institute of Computer Images and Graphics Zhejiang University Hangzhou 310027 China. State Key Laboratory of CAD&CG Zhejiang University Hangzhou 310027 China. china Institute of Metrology Zhejiang Hangzhou 310034 China

In computer aided geometric design, the degree reduction of the parameter curve is a key technique in data exchange and data compression. The various existing methods of degree reduction cannot decide whether the degree reduction curve satisfying the given tolerance exists beforehand, cannot give approximation of the best multi-degree reduction, or cannot provide explicit expression and error formula of the degree reduction curve. In this paper, we propose an entirely new method, which can hurdle the above flaws completely. For a given Bézier curve of degree n, we can easily decide whether a Bézier reduction curve of degree m exists, which has equal derivatives with the given curve up to （r-1）-th and （s-1）-th orders （r,s≤m） respectively at the endpoints, so the approximating error is less than the given tolerance ε in the L2-norm. If the curve exists, the explicit expression can be given.

关键词： computer aided design Bézier curve degree reduction L2-norm tolerance.