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1.
We study theoretically a nonlinear response of the planar metal/dielectric nanostructures constituted from periodical array
of ultra thin silver layers and the layers of Kerr-like nonlinear dielectric. We predict hysteresis-type dependences of the
components of the tensor of effective dielectric permittivity on the field intensity allowing the change in material transmission
properties from transparent to opaque and back at extremely low intensities of the light. It makes possible to control the
light by light in all-optical nanoscale devices and circuits. 相似文献
2.
3.
Simin Cao Haoyang Li Zenan Zhao Sanjun Zhang Jinquan Chen Jianhua Xu Jay R. Knutson Ludwig Brand 《Molecules (Basel, Switzerland)》2021,26(1)
In this review, the experimental set-up and functional characteristics of single-wavelength and broad-band femtosecond upconversion spectrophotofluorometers developed in our laboratory are described. We discuss applications of this technique to biophysical problems, such as ultrafast fluorescence quenching and solvation dynamics of tryptophan, peptides, proteins, reduced nicotinamide adenine dinucleotide (NADH), and nucleic acids. In the tryptophan dynamics field, especially for proteins, two types of solvation dynamics on different time scales have been well explored: ~1 ps for bulk water, and tens of picoseconds for “biological water”, a term that combines effects of water and macromolecule dynamics. In addition, some proteins also show quasi-static self-quenching (QSSQ) phenomena. Interestingly, in our more recent work, we also find that similar mixtures of quenching and solvation dynamics occur for the metabolic cofactor NADH. In this review, we add a brief overview of the emerging development of fluorescent RNA aptamers and their potential application to live cell imaging, while noting how ultrafast measurement may speed their optimization. 相似文献
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5.
T. V. Brantseva A. V. Antonov Yu. A. Gorbatkina M. L. Kerber T. P. Kravchenko A. A. Rybin 《Mechanics of Composite Materials》1999,35(6):453-460
A new device for studying the dynamic adhesive strength is created. A procedure for determining the dynamic adhesive strength in fiber—polymer systems under impact loading (pull-out technique) is developed. The adhesive strength of the interface of polymer—steel wire joints formed by polymers of different chemical nature (epoxy resin, polysulfone, and polypropylene) is examined. It is shown that the dynamic adhesive strength grows as the loading rate increases for all the systems under investigation and that the relationship between the adhesive strength and the loading rate,
, over a wide range of rates can be described by two straight lines corresponding to the quasi-static and impact loading, respectively. When passing from the quasi-static to dynamic loading, the character of scale relations of the adhesive strength does not change.Translated from Mekhanika Kompozitnykh Materialov, Vol. 35, No. 6, pp. 689–700, November–December, 1999. 相似文献
6.
Piotr Kowalczyk 《Transport in Porous Media》1993,11(3):281-295
The anatomy and geometry of the lung at the micro- and macroscopic level have been described briefly. A notion of lung parenchyma — a macroscopically continuous medium whose mechanical properties result from those of microstructural components — has been adapted. Simplifying assumptions propounded in the constitutive model have been discussed. Two phases have been distinguished in the medium: the solid phase — a highly deformable, nonlinearly elastic skeleton in the form of a thin-walled tissue structure on the micro-scale — and the fluid phase — perfect gas (air) filterating through the structure. General constitutive relations for both phases and their mechanical interactions have ben formulated. Further, the fundamental set of differential equations of the quasi-static coupled problem has been developed. Large deformations, material nonlinearities, and dependence of permeability on skeleton deformation have been included. Matrix formulation of the problem has been presented from the point of view of the finite element method. An implicit iterative time integration scheme has been proposed. The algorithm has been illustrated with results of simple numerical tests. 相似文献
7.
移动荷载作用下地基动力分析的有限元方法 总被引:3,自引:0,他引:3
通过对地基动力问题的基本方程进行变换,把基本方程变换到随荷载移动的运动坐标系中,通过加权残数法推导了相应的单元刚度矩阵,从而建立了移动问题的有限元格式,并发现移动荷载问题的单元刚度矩阵是对相应静力问题单元刚度矩阵的修正,在静力单元刚度矩阵的主对角元素上增加与移动速度有关的项,即可得到移动问题有限元的单元刚度矩阵,这样就将动力学问题转化为“拟静力”问题处理。文中用移动问题有限元方法计算了地基的动力响应,并与解析解进行了对比,以说明本方法具有较好的精度。 相似文献
8.
An elastic-viscoplastic constitutive model was adopted to analyze asymptotically the tip-field of moving crack in linear-hardening materials under plane strain condition. Under the assumption that the artificial viscosity coefficient was in inverse proportion to power law of the rate of effective plastic strain, it is obtained that stress and strain both possess power law singularity and the singularity exponent is uniquely determined by the power law exponent of the rate of effective plastic strain. Variations of zoning structure according to each material parameter were discussed by means of numerical computation for the tip-field of mode Ⅱ dynamic propagating crack, which show that the structure of crack tip field is dominated by hardening coefficient rather than viscosity coefficient. The secondary plastic zone can be ignored for weak hardening materials while the secondary plastic zone and the secondary elastic zone both have important influence on crack tip field for strong hardening materials. The dynamic solution approaches to the corresponding quasi-static solution when the crack moving speed goes to zero, and further approaches to the HR (Hui-Riedel) solution when the hardening coefficient is equal to zero. 相似文献
9.
The shear compression specimen (SCS), which is used for large strain testing, is thoroughly investigated numerically using
three-dimensional elastoplastic finite element simulations. In this first part of the study we address quasi-static loading.
A bi-linear material model is assumed. We investigate the effect of geometrical parameters, such as gage height and root radius,
on the stress and strain distribution and concentration. The analyses show that the stresses and strains are reasonably uniform
on a typical gage mid-section, and their average values reflect accurately the prescribed material model. We derive accurate
correlations between the averaged von Mises stress and strain and the applied experimental load and displacement. These relations
depend on the specimen geometry and the material properties. Numerical results are compared to experimental data, and an excellent
agreement is observed. This study confirms the potential of the SCS for large strain testing of material. 相似文献
10.
By using the adaptive steplength integration scheme with a shooting technique, a rather difficult singular perturbation problem
of ordinary differential equations with boundary layers can be calculated effectively. Computing examples are given in this
paper which show the convergence within one iteration of the method in the case of a linear problem, the efficiency of the
method for many boundary layers and turning points, especially the convenience in calculating multiple solutions. A comparison
with traditional difference method is given at the end of this paper. 相似文献