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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
Gabriel N. Gatica Ernst P. Stephan 《Numerical Methods for Partial Differential Equations》2002,18(1):105-128
This article deals with an expanded mixed finite element formulation, based on the Hu‐Washizu principle, for a nonlinear incompressible material in the plane. We follow our related previous works and introduce both the stress and the strain tensors as further unknowns, which yields a two‐fold saddle point operator equation as the corresponding variational formulation. A slight generalization of the classical Babu?ka‐Brezzi's theory is applied to prove unique solvability of the continuous and discrete formulations, and to derive the corresponding a priori error analysis. An extension of the well‐known PEERS space is used to define an stable associated Galerkin scheme. Finally, we provide an a posteriori error analysis based on the classical Bank‐Weiser approach. © 2002 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 18: 105–128, 2002 相似文献
983.
Let T be a suitable system of classical set theory. We will show, that the Σ1 spectrum of T, i.e. the set of ordinals having good Σ1 definition in T is an initial segment of the ordinals.
Received: 11 October 1999 / Published online: 12 December 2001 相似文献
984.
A. V. Ivanchenko S. A. Gromilov S. M. Zemskova I. A. Baidina L. A. Glinskaya 《Foundations of Physics Letters》2002,15(1):554-558
A new mixed-ligand complex, Cd(S2CN(C4H9)2)2Phen, is synthesized and investigated by thermal, element, and IR analyses and by diffractometry of polycrystals (DRON-3M, CuKα radiation, Ni filter). The crystal structure was determined on a CAD-4 Enraf-Nonius automatic diffractometer (MoKα radiation, θ from 1.5 to 25?, 2325 nonzero independent reflections, 190 refined parameters, R = 0.036 for I > 2Σ(I)). Crystal data for C30H44CdN4S4 : a = 15.592(3), b = 22.724(5), c = 9.922(2) å, space group Pbcn, V = 3515.5(12) å3, Z = 4, M = 701.33, dcalc = 1.325 g/cm3. The structure involves monomeric molecules in which the cadmium atom has a distorted octahedral environment. 相似文献
985.
Time-resolved electron paramagnetic resonance (TREPR) experiments are reported on an α-hydroxy acetophenone in waterg-glycerol and ethanol-ethanediol mixtures over a viscosity range of 1–32 cP. The magnitude and viscosity dependence of the radical pair mechanism polarization is in good agreement with theory. The triplet mechanism polarization is found to increase with decreasing solvent polarity and this is ascribed to an increase in the α-cleavage rate constant. The liquid spectra are used to interpret TREPR spectra of the acetophenone in dry and wet cotton. In dry cotton anti-phase structure is seen and is due to some of the radical pairs being trapped in cages. The triplet and radical pair mechanism polarization shows that the acetophenone adsorbs to the apolar crystallite surface and releases radicals into the polar amorphous regions where they experience a microviscosity of approximately 30 cP. In wet cotton there are no cages and the viscosity is greater than in ethanol alone. 相似文献
986.
This paper describes the performance and simulation of a compact integrated optical processor for the real-time reconstruction of two-dimensional images in airborne stripmap synthetic aperture radar applications. The functional behavior of the processor is explained in some detail. The design criteria are briefly given. The simulation step allowed the main processor characteristics and properties to be identified. A number of comparisons were obtained in airborne SAR mission scenarios between the predictions of the optical device and those achieved by the modern electronic digital approach, based on the wavefront reconstruction method by matched filtering. 相似文献
987.
Laser driven shocks can lead to a dynamic failure, called film spallation. Here, we use a modified laser spallation set-up
to measure the dynamic adhesion of thin films and we propose a novel diagnostic technology. Based on correlation theory, new
spallation criteria for characterizing the progressive damage at the interface between the film and the substrate are established,
such as interface delamination, film spallation and film expulsion. With the help of the theory, the degree of damage and
the dimension of damage (i.e. fracture), such as the minimum width of delamination radius, the thickness of the film etc.,
are estimated. Experiments are carried out on epoxy/stainless steel and epoxy/Al, and the experimental results show that their
dynamic bonding strengths are about 25 MPa and 20 MPa, respectively. The detailed results, analyses and discussions are presented
in this paper.
Received: 6 February 2001 / Accepted: 3 December 2001 / Published online: 11 February 2002 相似文献
988.
M. Gutowski I. Dabkowska J. Rak S. Xu J.M. Nilles D. Radisic K.H. Bowen Jr 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):431-439
The photoelectron spectra (PES) of anions of uracil-glycine and uracil-phenylalanine complexes reveal broad features with
maxima at 1.8 and 2.0 eV. The results of ab initio density functional B3LYP and second order M?ller-Plesset theory calculations indicate that the excess electron occupies a
π* orbital localized on uracil. The excess electron attachment to the complex can induce a barrier-free proton transfer (BFPT)
from the carboxylic group of glycine to the O8 atom of uracil. As a result, the four most stable structures of the anion of
uracil-glycine complex can be characterized as the neutral radical of hydrogenated uracil solvated by the anion of deprotonated
glycine. The similarity between the PES spectra for the uracil complexes with glycine and phenylalanine suggests that the
BFPT is also operative in the case of the latter anionic species. The BFPT to the O8 atom of uracil may be related to the
damage of nucleic acid bases by low energy electrons because the O8 atom is involved in a hydrogen bond with adenine in the
standard Watson-Crick pairing scheme.
Received 6 April 2002 Published online 13 September 2002 相似文献
989.
N.-K. Lee T.A. Vilgis 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(4):451-465
We study the elastic properties of single A/B random copolymer chains, with a specific sequence and use them as theoretical
model for so called HP proteins. HP proteins carry hydrophilic (P) and hydrophobic (H) monomers. We predict a rich structure
in the force-extension relations which can be attributed to the information in the sequence. The variational method is used
to probe local minima on the path of stretching and releasing for the chain molecules. At a given force, we find multiple
configurations which are separated by energy barriers. A collapsed globular configuration consists of several domains which
unravel cooperatively. Upon stretching, the unfolding path shows a stepwise pattern corresponding to the unfolding of each
domain. While releasing, several cores can be created simultaneously in the middle of the chain, resulting in a different
path of collapse. The long-range interactions and stiffness of the chain simplify the potential landscape given by the disorder
in sequence.
Received 5 March 2002 / Received in final form 16 May 2002 Published online 13 August 2002 相似文献
990.
Ying Zhang Gang Hu Shigang Chen H.A. Cerdeira 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(3):381-384
A method of controlling global stochasticity in Hamiltonian systems by applying nonlinear perturbation is proposed. With the
well-known standard map we demonstrate that this control method can convert global stochasticity into regular motion in a
wide chaotic region for arbitrary initial condition, in which the control signal remains very weak after a few kicks. The
system in which chaos has been controlled approximates to the original Hamiltonian system, and this approach appears robust
against small external noise. The mechanism underlying this high control efficiency is intuitively explained.
Received 15 January 2002 Published online 6 June 2002 相似文献