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311.
312.
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
313.
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
314.
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
315.
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
316.
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
317.
N. S. Smirnova 《Journal of Mathematical Sciences》1991,55(3):1741-1746
We consider theoretical seismographs of a wave field passing through an elastic layer with high propagation velocity. We note the presence of a low-frequency part of the seismogram for longitudinal waves. It is shown that the propagation time of low-frequency vibrations is equal to that of longitudinal disturbances screened by the layer.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova, AN SSSR, Vol. 173, pp. 134–141, 1988. 相似文献
318.
N. L. Vekshin 《Journal of Applied Spectroscopy》1991,54(1):17-22
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 1, pp. 26–32, January, 1991. 相似文献
319.
Recently published data on thep T dependence of the angular distributions of muon pairs produced in collisions of negative pions with deuterium and tungsten nuclei reveal an unexpected tendency. We show that the quantum statistical approach involving expansions in terms of coherent states leads in this case to an exact, non-perturbative result which in the lowest order approximation describes the observed trends with sufficient accuracy. In this procedure, the non-vanishing correlations between the coordinates and momenta of dimuons play a decisive role. 相似文献
320.