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71.
Despite considerable presence of periodic multilayers with wavy architectures in nature and technology, little simulation data is available on their response. A recent investigation of wavy multilayers comprised of alternating elastic and elastic-perfectly plastic plies has revealed the important role that plasticity plays on their post-yield response relative to the corresponding flat configurations [Khatam, H., Pindera, M.-J., 2009b. Parametric finite-volume micromechanics of periodic materials with elastoplastic phases. Int. J. Plasticity 25 (7), 1386–1411]. Herein, we extend this investigation by considering the effect of elastic layer thickness on the post-yield response at several fixed elastic phase volume fractions using the parametric finite-volume direct averaging micromechanics (FVDAM) theory. The layer thickness is shown to have a substantial impact on the post-yield response whose extent depends on the loading mode and waviness amplitude, in contrast with the minimal impact on the homogenized elastic moduli. Decreasing the layer thickness at sufficiently high fixed volume fractions decreases the extent of strain hardening under transverse normal loading, as well as the maximum normal and shear stresses in the stiff layers, reducing the possibility of failure and thus potentially enhancing durability. The opposite holds under transverse shear loading for low waviness amplitudes. The presented results provide a framework for tailoring the elastoplastic response of multilayers with sinusoidally varying plies under different loading modes. 相似文献
72.
O. Bourgeois P. Gandit J. Lesueur A. Sulpice X. Grison J. Chaussy 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(1):75-80
We report transport measurements on Superconductor/Ferromagnet/Superconductor (S/F/S) junctions: Nb/Al/Gd/Al/Nb where gadolinium
(Gd) is a weakly polarized ferromagnet. A sizeable critical current I
c is observed in the I(V) characteristics. This current can be modulated by a weak magnetic field, as expected for a Josephson current. With these
experiments, we establish that superconducting coherent transport survives across a small ferromagnetic layer. The penetration
depth of Cooper pairs in Gd has been measured. An extensive study of the Josephson critical current in temperature for different
thicknesses of magnetic compounds is presented. A comparison of transport measurements with S/N/S junction is given through
measurements made on Nb/Al/Y/Al/Nb, where yttrium (Y) is used as non magnetic rare earth metal.
Received 20 September 2000 and Received in final form 22 February 2001 相似文献
73.
Electronic structures in coupled two quantum dots by 3D-mesh Hartree-Fock-Kohn-Sham calculation 总被引:2,自引:0,他引:2
T. Matsuse T. Hama H. Kaihatsu N. Toyoda T. Takizawa 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):391-394
To study the electronic structures of quantum dots in the framework of self-interaction-free including three dimensional effects,
we adopt the theory of nonlocal effective potential introduced by Kohn and Sham [#!ks65!#]. For utilizing the advantageous
point of the real space (3D) mesh method to solve the original nonlinear and nonlocal Hartree-Fock-Kohn-Sham (HFKS)-equation,
we introduce a linearization of the equation in the local form by introducing the local Coulomb potentials which depend on
explicitly the two single particle states. In practice, for solving the local form HFKS-equation, we use the Car-Parrinello-like
relaxation method and the Coulomb potentials are obtained by solving the Poisson equation under proper boundary conditions.
Firstly the observed energy gap between triplet- and singlet-states of N = 4 in DBS [#!tarucha96!#] is discussed to reproduce the addition energies and chemical potentials depending the magnetic
field. Next the coupling between two-quantum dots in TBS [#!aht97!#] is studied by adding the square barrier between two dots.
The spin-degeneracy [#!aht97!#] measured in gate-voltage depending on magnetic field is well reproduced in the limit of small
mismatch. Finally, the electronic states in the ring structure are calculated and discussed how the ring size and magnetic
field affect to the structures.
Received 30 November 2000 相似文献
74.
M.A. Gilmore B.L. Johnson 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(3):297-305
We study the effects of layer thickness variations on the collective plasmon excitation modes of finite superlattices. Unlike
other symmetry lowering mechanisms, thickness variation does not strongly localize the surface modes. We find that the reason
for this insensitivity lies in the fact that the collective modes of a given finite structure must evolve continuously from
the single-finite-superlattice at zero thickness deviation into modes of a pair of uncoupled finite structures at large thickness
variation. We also show that this behavior is analogous to the evolution of molecular orbitals from atomic orbitals as the
internuclear separation is reduced, in contrast to the analogy of the superlattice modes as a stack of coupled quantum wells.
This emphasizes the difference between the electromagnetic symmetry of the finite superlattice and the structural symmetry.
Received 16 April 2001 and Received in final form 6 July 2001 相似文献
75.
M. Langlet M. Burgos C. Coutier C. Jimenez C. Morant M. Manso 《Journal of Sol-Gel Science and Technology》2001,22(1-2):139-150
TiO2 sol-gel thin films have attracted a large attention for applications which require high refractive index transparent layers. In this work, sol-gel TiO2 layers were prepared by Aerosol-gel deposition followed by a thermal treatment procedure in air. Depending on the experimental conditions, abrasion resistant and high refractive index layers could be obtained after post-treatment at only 110°C. In this paper, the experimental parameters which allow the preparation of functional TiO2 sol-gel layers at such low temperature are discussed. It is concluded that the preparation of high refractive index and mechanically resistant TiO2 layers can be interpreted in terms of competition between polycondensation and densification mechanisms. This result allows to envisage the sol-gel processing at low temperature of multilayer antireflective coatings. 相似文献
76.
77.
J. Osterwalder T. Greber E. Wetli J. Wider H. J. Neff 《Progress in Surface Science》2000,64(3-8):65-87
The routine measurement of full hemispherical photoemission intensity maps gives us the possibility for the combined investigation of structural and electronic phenomena at surfaces. As an example the growth of ultrathin films of Co on Cu(111) is studied as a function of film thickness. While X-ray photoelectron diffraction (XPD) shows the early appearance of stacking faults as a precursor of the hcp structure, Fermi surface maps reveal the very fast evolution of the Co Fermi surface that can be compared to measurements on a clean Co(0001) crystal. For the system O/Rh(111), XPD brings up important structural clues, relating changes in surface reactivity to small amounts of subsurface oxygen, which forces adjacent oxygen atoms to occupy new and more reactive adsorption sites. In the course of this last study we observed for the first time the weak backscattering signals in the angular pattern of adsorbate emission. These cone-like features are extremely sensitive to the adsorbate–substrate bond length. 相似文献
78.
Tonya D. Andreeva Andrs Dr Lrnd Kelemen Rumen Krastev Stefka G. Taneva 《先进技术聚合物》2020,31(7):1562-1570
Controlling the surface properties and structure of thin nanosized coatings is of primary importance in diverse engineering and medical applications. Here we report on how the nanostructure, growth mechanism, thickness, roughness, and hydrophilicity of nanocomposites composed of weak natural or strong synthetic polyelectrolytes (PE) can be tailored by graphene oxide (GO) doping. GO reverses the build‐up mechanism affecting the internal structure and the hydrophilicity in a way depending on the type of the PE‐matrix. The extent of GO‐adsorption and its impact on the surface morphology was found to be independent on the type of the underlying PE‐matrix. The nanostructure of the hybrid films is not significantly altered when a single surface‐exposed GO‐layer is deposited, while increasing the number of embedded GO‐layers leads to pronounced surface heterogeneity. These results are expected to have valuable impact on the construction strategies of coatings with tunable surface properties. 相似文献
79.
Andrea Locatelli Daniele Modotto Costantino De Angelis Filippo Maria Pigozzo Antonio-Daniele Capobianco 《Optical and Quantum Electronics》2005,37(1-3):121-131
We propose a time domain bidirectional beam propagation method based on scattering operators for wide band pulse propagation in nonlinear multilayers. The reported numerical examples demonstrate the applicability of the algorithm for the analysis of temporal effects related to the process of second harmonic generation. 相似文献
80.
多层膜软X光反射镜的研制 总被引:1,自引:0,他引:1
本文介绍了镍-碳多层膜软X光反射镜的设计与制造方法,特别是膜厚监控法.用俄歇谱仪分析了一个样品的剖面情况;对一些样品在1.54(?)的衍射特性和在软X光区的反射率进行了测量并与理论计算结果作了比较. 相似文献