共查询到20条相似文献,搜索用时 640 毫秒
1.
Russian Physics Journal - Using the methods of transmission electron microscopy, new aspects of formation of reorientation nanobands with partial involvement of nondislocational deformation... 相似文献
2.
Russian Physics Journal - Based on the results of electron microscopy examinations, a theoretical study of the distortion tensors of strain localization nanobands with a 90°... 相似文献
3.
W.L. Zhou E.E. Carpenter J. Lin A. Kumbhar J. Sims C.J. O'Connor 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):289-292
Pure metal iron nanoparticles are unstable in the air. By a coating iron on nanoparticle surface with a stable noble metal,
these air-stable nanoparticles are protected from the oxidation and retain most of the favorable magnetic properties, which
possess the potential application in high density memory device by forming self-assembling nanoarrays. Gold-coated iron core-shell
structure nanoparticles (Fe/Au) synthesized using reverse micelles were characterized by transmission electron microscopy
(TEM). The average nanoparticle size of the core-shell structure is about 8 nm, with about 6 nm diameter core and 1∼2 nm shell.
Since the gold shell is not epitaxial growth related to the iron core, the morié pattern can be seen from the overlapping
of iron core and gold shell. However, the gold shell lattice can be seen by changing the defocus of TEM. An energy dispersive
X-ray spectrum (EDS) also shows the nanoparticles are air-stable. The magnetic measurement of the nanoparticles also proved
successful synthesis of gold coated iron core-shell structure. The nanoparticles were then assembled under 0.5 T magnetic
field and formed parallel nanobands with about 10 μm long. Assembling two dimensional ordered nanoarrays are still under going.
Received 29 November 2000 相似文献
4.
5.
利用大学物理实验中的光杠杆法测定金属丝弹性模量的原理和设备,对具有超弹性的NiTi丝的弹性滞后环进行了测定结果表明,此种方法可以很好地测定NiTi丝的弹性滞后环,而且操作简单使用方便,是一种非常有效的测定金属细丝弹性滞后环的方法. 相似文献
6.
The differential, total and transport elastic cross sections are calculated with an adiabatic effective (µ––H) potential and with regard to inelastic transitions. The elastic cross section is greater than the inelastic one by an order of value in the atomic-capture energy region. The excess increases with particle mass. The effect of the elastic scattering on the energy distribution of Coulomb capture is considered within the approximation of continuous elastic energy losses. An appreciable increase of the capture probability due to elastic scattering is obtained in the low-energy region. 相似文献
7.
8.
9.
10.
《Comptes Rendus Physique》2009,10(8):728-739
In this short review I argue that the progress in our understanding the mechanism of turbulent drag reduction is conditioned by obtaining experimental data on dynamics and statistics of polymer stretching and elastic stresses in inertial turbulence at high Reynolds numbers that is a technically challenging task. The suggested way out of the currently unresolved technical problem is to collect the same data in elastic turbulence, which is a smooth random flow similar to that found in inertial turbulence below the dissipation scale. Since the polymer stretching and elastic stresses in inertial turbulence are influenced only by small scales, it is appropriate to use information on the polymer stretching and elastic stresses obtained in elastic turbulence. The experimental data on the statistics of the polymer stretching, the coil–stretch transition, and elastic stresses together with spatial distribution and values of the rms of the velocity gradients were collected in elastic turbulence for the last several years. This information serves a basis for a new hypothesis of turbulent drag reduction. To cite this article: V. Steinberg, C. R. Physique 10 (2009). 相似文献
11.
利用一维固-固结构圆柱声子晶体中弹性波横向受限的条件,推导出弹性波在其中各个模式满足的关系式,利用它研究了弹性波各模式的特性.并利用转移矩阵研究了弹性波的传输特性随模式量子数和圆柱半径的变化规律.得出了一些一维固-固结构圆柱声子晶体的新特征,即弹性波的传输特性由模式量子数和圆柱半径决定.
关键词:
圆柱声子晶体
弹性波
受限
模式 相似文献
12.
V. M. Rodyushkin 《Ultrasonics》1995,33(6):437-439
It is known that ultrasound can be used to measure the constant in time deformations and residual stresses, through the acoustoelasticity effect. The method presented here is different from this principle. It is based on the non-resonant parametric interaction of elastic waves and enables measurement of the dynamic deformation in elastic media. The aim of this work is to investigate the interaction of waves in non-linear elastic media with the deformation fields in parametric approximation and to create a method that permits observation (in three-dimensions) of the dynamic stress-state of the opaque elements of a structure. In particular, interest in the solution of this problem arises for high-frequency non-stationary loading on the structure, when it is impossible to determine the internal stress-state of the elastic body by measurement of the vibration of its surface. The solution to this is found by using ultrasonic waves as a type of transducer that can freely penetrate the elastic body in the necessary direction. 相似文献
13.
E. G. Sheikin 《Technical Physics》2010,55(1):1-9
A new model differential cross section is proposed for describing elastic scattering of electrons in simulating the passage
of electrons through a substance by the Monte Carlo method. This differential cross section correctly describes the first
and second transport scattering cross sections, but is characterized by the total elastic scattering cross section much smaller
than the actual value of the total elastic scattering cross section. The application of this differential cross section makes
it possible to considerably reduce the number of elastic collisions in the Monte Carlo simulation of passage of electrons
in a substance and to model the passage of high-energy electrons using the individual collision model. 相似文献
14.
Cells play an active role in the maintenance of mechanical homeostasis within tissues and their response to elastic forces is important for tissue engineering. We predict the collective response of an ensemble of contractile cells in a three-dimensional elastic medium to externally applied strain fields. Motivated by experiment, we model the cells as polarizable force dipoles that change their orientation in response to the local elastic strain. The analogy between the mechanical response of these systems and the dielectric response of polar molecules is used to calculate the elastic response function. We use this analogy to evaluate the average cell orientation, the mean polarization stress, and the effective elastic constants of the material, as a function of the cell concentration and matrix properties. 相似文献
15.
向列液晶预倾角与其弹性常量的相关性研究 总被引:3,自引:2,他引:1
向列液晶分子在基片上形成预倾角是液晶分子进行重新排列取向的过程,预倾角的大小会影响与取向相关的向列液晶的弹性变形行为.本文通过设置不同的预倾角,在不同的温度下用激光散射技术测量向列液晶的弛豫系数,从而获得液晶的弹性常量,并研究弹性常量随预倾角的变化规律.研究结果表明,当预倾角小于某一角度,由于向列液晶分子内部排列不规整而无法体现其整体的弹性变形特征;当预倾角达到一定的角度,向列液晶就表现出最大的弹性常量值,液晶特有的弹性变形行为得以充分的体现. 相似文献
16.
黏弹性吸声材料复弹性模量优化研究 总被引:4,自引:0,他引:4
针对黏弹性材料吸声效率问题,利用分层介质声传播理论和数值算法优化了不同物理条件下材料的复弹性模量。采用参数等效的方法分析了含气泡黏弹性材料的声学特性,并给出了此种材料优化后的弹性模量曲线。根据物理模型计算了一定边界条件下材料复弹性模量等吸声系数曲线,得到了几种背衬条件下黏弹性材料吸声系数大于0.8的弹性模量和损耗因子范围。研究表明调节黏弹性材料的复弹性模量可以有效提高材料的吸声性能,吸声系数大于0.8时其弹性模量和损耗因子范围在不同背衬条件下差异较大,发现一定厚度的钢背衬会降低调控复弹性模量的难度,对含气泡黏弹性材料的计算也可得到类似结果。 相似文献
17.
The complete set of non-vanishing third-order elastic constants of the semiconductors ZnS and ZnSe is obtained theoretically. The strain energy density is estimated using finite strain elasticity theory by considering the interactions up to two nearest neighbours of each atom in the unit cell of these compounds. This energy density is compared with the strain dependent lattice energy density from the continuum model approximation. The second-order parameter of the potential function φ is obtained from the measured principal axis Cij. The third-order potential parameter is estimated by assuming a Lennard-Jones type of interatomic potential. The interlattice displacements as well as the second-order elastic constants are evaluated along with the six third-order elastic constants of ZnS and ZnSe. Using these second- and third-order elastic constants of ZnS, the pressure derivatives of second-order elastic constants are evaluated. The second- and third-order elastic constants of ZnSe are compared with the available experimental values. The third-order elastic constants show anisotropy in different directions. 相似文献
18.
The elastic field of centres of dilatation at arbitrary positions in a spherical specimen with cubic elastic constants is studied. The influence of the (free) boundary, which is of central importance due to the long-range nature of the elastic interaction, is included. For materials with small elastic anisotropy expansions in terms of vector spherical harmonics are obtained for the displacements due to one defect, as well as for the interaction energy of two defects. Infinite material expressions and surface contributions are given separately. The general treatment is exemplified by presenting explicit results for the case of hydrogen atoms dissolved in vanadium. 相似文献
19.
Nematic liquid crystals are shown to be able to visualize elastic deformations even if no dynamic scattering is present. At
low values of the elastic energy density, by observing the excited birefringence it is possible to map the normal modes of
the elastic disturbance. At higher energy density a cellular motion (rolls) is produced which, in the homeotropic geometry,
gives rise to a domain pattern which allows to visualize the velocity field.
Work supported by Gruppo Nazionale di Struttura della Materia (GNSM) of CNR. 相似文献
20.
Calculation of Elastic Constants of Ag/Pd Superlattice Thin Films by Molecular Dynamics with Many-Body Potentials 下载免费PDF全文
The calculation of elastic constants of Ag/Pd superlattice thin films by molecular dynamics simulations with many-body potentials is presented. It reveals that the elastic constants C11 and C55 increase with decreasing modulation wavelength A of the films, which is consistent with experiments. However, the change of C11 and C55 with A is found to be around the values determined by a rule of mixture using bulk elastic constants of metals. No supermodulus effect is observed and it is due to cancellation between enhanced and reduced contributions to elastic constants from Ag and Pd layers subjected to compressive and tensile strains, respectively. 相似文献