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141.
目前,多边形表面模型是最常用的一种三维几何模型表示方法.然而这种复杂的三维几何模型经常超过了系统的处理能力,既占据大量的存储空间,也不利于互联网传输.针对这一缺陷,文章提供一种使用X3D的Indexed Triangle Strip Set节点构造不规则圆柱体模型的方法.不规则圆柱体采用层数及每一层半径表示方法,并结合曲面精度一同拟合3D几何面.此方法具有模型构建精度高的特点. 相似文献
142.
M. Sajid 《Numerical Methods for Partial Differential Equations》2010,26(1):221-228
This article investigates the analytic solution for the flow of a third grade fluid past an infinite porous plate. The method of parameter differentiation is used to linearized the governing flow equation. The solution of the obtained linear equation is developed by differential transform method in combination with the method of superposition. The obtained results are compared with existing results in the literature and an excellent agreement is found. This shows that the parameter differentiation is a powerful technique for solving nonlinear problems. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2010 相似文献
143.
V.I. Afonso D. Bazeia M.A. Gonzalez Len L. Losano J. Mateos Guilarte 《Nuclear Physics B》2009,810(3):427-459
This work deals with the construction of networks of topological defects in models described by a single complex scalar field. We take advantage of the deformation procedure recently used to describe kinklike defects in order to build networks of topological defects, which appear from complex field models with potentials that engender a finite number of isolated minima, both in the case where the minima present discrete symmetry, and in the non-symmetric case. We show that the presence of symmetry guide us to the construction of regular networks, while the non-symmetric case gives rise to irregular networks which spread throughout the complex field space. We also discuss bifurcation, a phenomenon that appear in the non-symmetric case, but is washed out by the deformation procedure used in the present work. 相似文献
144.
Ronald G. Larson 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2012,124(11):2596-2598
145.
Matthias Schulz Susanne Tanner Haitham Barqawi Wolfgang H. Binder 《Journal of polymer science. Part A, Polymer chemistry》2010,48(3):671-680
The end‐to‐end cyclization of telechelic polyisobutylenes (PIB's) toward cyclic polyisobutylenes is reported, using either ring‐closing metathesis (RCM) or the azide/alkyne‐“click”‐reaction. The first approach uses bisallyl‐telchelic PIB's (Mn = 1650, 3680, 9770 g mol?1) and Grubbs 1st‐, 2nd‐, and 3rd‐generation catalyst leading to cyclic PIB's in 60–80% yield, with narrow polydispersities (Mw/Mn = 1.25). Azide/alkyne‐“click”‐reactions of bisalkyne‐telechelic PIB's (Mn = 3840 and 9820 g mol?1) with excess of 1,11‐diazido‐undecane leads to the formation of mixtures of linear/cyclic PIB's under formation of oligomeric cycles. Subsequent reaction of the residual azide‐moieties in the linear PIB's with excess of alkyne‐telechelic PEO enables the chromatographic removal of the resulting linear PEO‐PIB‐block copolymers by column chromatography. Thus pure cyclic PIB's can be obtained using this double‐“click”‐method, devoid of linear contaminants. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 671–680, 2010 相似文献
146.
When certain trivalent rare-earth ions (Ln's) are co-doped in CaGa2S4:Mn2+ as sensitizers, the Mn red emission of the compound is strikingly enhanced. In this work, efficiency of each lanthanide is studied. The best efficiencies are achieved with La3+-, Pr3+-, and Tb3+- co-doped compounds, for each of which the effects of concentrations of the co-doped ions on the Mn2+ emission are investigated. The energy-transfer mechanisms and the location of electronic energy levels of both the trivalent and the divalent lanthanides in the energy band gap of the host material are discussed. Depending on Ln's, charge transfer or cross-relaxation should be taken into account. 相似文献
147.
Steady-state and time-resolved techniques are used to study photoinduced electron and/or excitational energy transfer processes involved within a novel donor (zinc tetraphenylporphyrin)-acceptor (9-cyanoanthracene) system in a polar liquid medium (acetonitrile) at the ambient temperature (300 K). After photoexcitation of 9-cyanoanthracene, its fluorescence emission as well as lifetime are found to be quenched in presence of zinc tetraphenylporphyrin. The fluorescence quenching is ascribed to be due to the combined effect of electron transfer from zinc tetraphenylporphyrin to 9-cyanoanthracene and energy transfer (radiative as well as non-radiative) from 9-cyanoanthracene to zinc tetraphenylporphyrin. The highly exergonic values of Gibbs free energy change for both forward electron transfer reaction (−1.15 eV) and charge recombination reaction (−1.94 eV) indicate the possibilities of occurrences of these two processes in the Marcus inverted region. The fluorescence quenching rate due to photoinduced electron transfer reaction is found to be close to the diffusion-controlled limit within the present donor-acceptor system upon excitation of the acceptor molecules. 相似文献
148.
A. H.M. Zaheri S. Srivastava K. Tankeshwar 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(4):465-473
Expressions for zeroth, second and fourth sum rules of longitudinal and bulk
stress auto correlation functions have been derived for binary fluid mixtures.
Longitudinal and bulk viscosities of an Ar–Kr mixture have been calculated using
Mori's memory function formalism coupled with the sum rules of longitudinal and
bulk stress auto correlation functions.
The results obtained are compared with the molecular dynamics
simulation. Mass dependence of the longitudinal and bulk viscosities has
been studied for different compositions
of an isotopic mixture at different densities and temperatures. For very large mass ratio, the
longitudinal and bulk viscosities of the isotopic mixture are more dependent on mole fraction than on mass. 相似文献
149.
《科学通报(英文版)》1989,34(11):902-902
150.
设{X_n,n≥1}为独立同分布序列,公共分布函数为F(x),为第k个最大值。在一定条件下,讨论了第k个规范化最大值的矩收敛性,得到定理若F∈D(H),则n→∞时 相似文献