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141.
We examine the smoothness properties of the principal curvatures of subdivision surfaces near irregular points. In particular we give an estimate of their L
p
class based on the eigenstructure of the subdivision matrix. As a result we can show that the popular Loop and Catmull–Clark schemes (among many others) have square integrable principal curvatures enabling their use as shape functions in FEM treatments of the thin shell equations. 相似文献
142.
In this work we derive lower bounds for the Hausdorff and fractal dimensions of the global attractor of the Sabra shell model
of turbulence in different regimes of parameters. We show that for a particular choice of the forcing term and for sufficiently
small viscosity term ν, the Sabra shell model has a global attractor of large Hausdorff and fractal dimensions proportional
to log ν −1 for all values of the governing parameter ε, except for ε =1. The obtained lower bounds are sharp, matching the upper bounds
for the dimension of the global attractor obtained in our previous work. Moreover, the complexity of the dynamics of the shell
model increases as the viscosity ν tends to zero, and we describe a precise scenario of successive bifurcations for different
parameters regimes. In the “three-dimensional” regime of parameters this scenario changes when the parameter ε becomes sufficiently
close to 0 or to 1. We also show that in the “two-dimensional” regime of parameters, for a certain non-zero forcing term,
the long-term dynamics of the model becomes trivial for every value of the viscosity.
AMS Subject Classifications: 76F20, 76D05, 35Q30 相似文献
143.
Reduced-temperature ordering of FePt nanoparticle assembled films by Fe30Pt70/Fe3O4 core/shell structure
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In this paper, Fe30Pt70/Fe3O4 core/shell nanoparticles were synthesized by chemical routine and the layered polyethylenimine (PEI)-Fe30Pt70/Fe3O4 structure was constructed by molecule-mediated self-assembly technique. The dimension of core/shell structured nanoparticles was that of 4nm core and 2 nm shell. After annealing under a flow of forming gas (50%Ar2+30%H2) for 1 h at or above 400℃, the iron oxide shell was reduced to Fe and diffused to Pt-rieh core, which leaded to the formation of L1. phase FePt at low temperature. The x-ray diffraction results and magnetic properties measurement showed that the chemical ordering temperature of Fe30Pt70/Fe3O4 core/shell nanoparticles assembly can be reduced to as low as 400℃. The sample annealed at 400℃ showed the eoereivity of 4KOe with the applied field of 1.5T. The core/shell structure was suggested to be an effective way to reduce the ordering temperature obviously.[第一段] 相似文献
144.
Floraine Collette Régis Delatouche Christophe Blanquart Fabien Gueugnon Marc Grégoire Philippe Bertrand Valérie Héroguez 《Journal of polymer science. Part A, Polymer chemistry》2013,51(1):176-189
In this contribution, a versatile approach for the synthesis of functionalized particles for drug delivery is presented, using two nonaggressive standardized procedures. The first procedure considered is the functionalization of an azido‐terminated α‐norbornenyl poly(ethylene oxide) (PEO) macromonomer with an alkyne‐containing active molecule via the copper catalyzed azide alkyne cycloaddition, click type reaction. The functionalized macromonomer is then polymerized by Ring‐Opening Metathesis Polymerization (ROMP) in dispersion to form functionalized particles. The second procedure consists in synthesizing particles by ROMP in dispersed media of norbornene with azido‐terminated α‐norbornenyl PEO macromonomer. The ROMP was initiated by the first generation Grubbs catalyst. Such functionalized core‐shell particles have stealthy properties due to their PEO shell and can be viewed as universal nanocarriers on which any alkyne‐modified active molecule can be grafted by click chemistry. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
145.
Saram Lee Segyeong Joo Sejin Park Soyoun Kim Hee Chan Kim Taek Dong Chung 《Electrophoresis》2010,31(10):1623-1629
In this study, in situ surface‐enhanced Raman scattering (SERS) decoding was demonstrated in microfluidic chips using novel thin micro gold shells modified with Raman tags. The micro gold shells were fabricated using electroless gold plating on PMMA beads with diameter of 15 μm. These shells were sophisticatedly optimized to produce the maximum SERS intensity, which minimized the exposure time for quick and safe decoding. The shell surfaces produced well‐defined SERS spectra even at an extremely short exposure time, 1 ms, for a single micro gold shell combined with Raman tags such as 2‐naphthalenethiol and benzenethiol. The consecutive SERS spectra from a variety of combinations of Raman tags were successfully acquired from the micro gold shells moving in 25 μm deep and 75 μm wide channels on a glass microfluidic chip. The proposed functionalized micro gold shells exhibited the potential of an on‐chip microfluidic SERS decoding strategy for micro suspension array. 相似文献
146.
The Hill's quadric anisotropy yield function and the Barlat-Lian anisotropy yield function describing well anisotropy sheet
metal with stronger texture are introduced into a quadric-flow corner constitutive theory of elastic-plastic finite deformation
suitable for deformation localization analysis. And then, the elastic-plastic large deformation finite element formulation
based on the virtual power principle and the discrete Kirchhoff shell element model including the yield functions and the
constitutive theory are established. The focus of the present research is on the numerical simulation of the flange earing
of the deep-drawing of anisotropy circular sheets, based on the investigated results, the schemes for controlling the flange
earing are proposed.
Supported by NSFC(No. 19832020) and National Automobile Dynamic Simulation Laboratory of China. 相似文献
147.
Micron-sized monodispersed polystyrene (PS)/poly(3,5-xylidine) (PXy) composite particles were produced by chemical oxidative
seeded dispersion polymerization of 3,5-xylidine at 20 °C with 1.6-μm-sized monodispersed PS seed particles in HCl aqueous
solution, the pH of which was always kept at 2.5 with a pH stat. The composite particles produced consisted of a PS core and
a PXy shell.
Received: 16 December 1998 Accepted in revised form: 25 March 1999 相似文献
148.
Zhenping Cheng Lifen Zhang Xiulin Zhu E. T. Kang K. G. Neoh 《Journal of polymer science. Part A, Polymer chemistry》2008,46(6):2119-2131
Crosslinked poly(4‐vinylbenzyl chloride) (PVBC) nanospheres of about 160 nm were first synthesized by emulsion copolymerization of 4‐vinylbenzyl chloride (VBC) in the presence of a crosslinking agent, p‐divinylbenzene. Subsequent modification of the nanosphere surfaces via surface‐initiated atom transfer radical polymerization of 4‐vinylpyridine, using the VBC units of PVBC on the nanosphere surface as the macroinitiators, produced a well‐defined and covalently tethered poly(4‐vinylpyridine) (P4VP) shells of 24–27 nm in thickness. Activation of the P4VP shells in a PdCl2 solution, followed by reactions with CO or H2S gas, gave rise to the corresponding P4VP composite shells containing densely dispersed palladium metal or palladium sulfide nanoparticles. The chemical composition of the nanosphere surfaces at various stages of surface modification was characterized by X‐ray photoelectron spectroscopy. Field emission scanning electron microscopy and transmission electron microscopy were used to characterize the morphology of the organic/inorganic hybrid nanospheres coated with palladium/P4VP shells. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2119–2131, 2008 相似文献
149.
A quasi-three-dimensional shell element model, which can be effectively used to simulate the flanging and spring-back deformation,
is introduced into the independently developed CAE software, KMAS. In this model, a double surface contact algorithm, which
allows the gap between punch and die to change, and a spring-back treatment scheme based on finite element meshing are described.
And then the flanging and spring-back deformations of the retractor's kickstand of a railcar made of stamped thick metal plate
are numerically simulated. The simulation results of flanging deformation are compared with those of international commercial
software, PAM-STAMP, and experimental ones. Finally, a predicting scheme of spring-back quantily for this problem is given.
Project supported by the National Natural Science Foundation of China (No. 19832020) and the Ministry of Education of China. 相似文献
150.
A method is proposed to solve the contact problem for laminated anisotropic shells of revolution. The method is based on a two-dimensional model that accounts for transverse shears and reduction. Also the method is based on the method of successive approximations, the generalized pseudo-force method, and a numerical-analytical method of solving boundary-value problems. The results obtained for a cylindrical shell of complex thickness structure are compared with those obtained in three-dimensional formulation__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 5, pp. 68–75, May 2005. 相似文献