共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
V. Shikin 《JETP Letters》2002,76(6):355-359
The origin of the specific activation-type behavior of the mobility of electrons on liquid-helium films with different kinds of substrates is discussed. The characteristic feature of the activation energy E a observed in the experiment is its dependence on the effective film thickness d in the form E a∝d ?2. A scenario of this effect is proposed with consideration for the roughness of the substrate underlying the liquid-helium film. 相似文献
3.
4.
5.
6.
Modeling of the rough spherical nanoparticles manipulation on a substrate based on the AFM nanorobot
In this paper, dynamic behavior of the rough spherical micro/nanoparticles during pulling/pushing on the flat substrate has been investigated and analyzed. For this purpose, at first, two hexagonal roughness models (George and Cooper) were studied and then evaluations for adhesion force were determined for rough particle manipulation on flat substrate. These two models were then changed by using of the Rabinovich theory. Evaluations were determined for contact adhesion force between rough particle and flat substrate; depth of penetration evaluations were determined by the Johnson–Kendall–Roberts contact mechanic theory and the Schwartz method and according to Cooper and George roughness models. Then, the novel contact theory was used to determine a dynamic model for rough micro/nanoparticle manipulation on flat substrate. Finally, simulation of particle dynamic behavior was implemented during pushing of rough spherical gold particles with radii of 50, 150, 400, 600, and 1,000 nm. Results derived from simulations of particles with several rates of roughness on flat substrate indicated that compared to results for flat particles, inherent roughness on particles might reduce the rate of critical force needed for sliding and rolling given particles. Given a fixed radius for roughness value and increased roughness height, evaluations for sliding and rolling critical forces showed greater reduction. Alternately, the rate of critical force was shown to reduce relative to an increased roughness radius. With respect to both models, based on the George roughness model, the predicted rate of adhesion force was greater than that determined in the Cooper roughness model, and as a result, the predicted rate of critical force based on the George roughness model was closer to the critical force value of flat particle. 相似文献
7.
The anchoring properties of substrate with a grating surface are
investigated analytically. The alignment of nematic liquid
crystal (NLC) in a grating surface originates from two
mechanisms, thus the anchoring energy consists of two parts. One
originates from the interaction potential between NLC molecules
and the molecules on the substrate surface, and the other stems
from the increased elastic strain energy. Based on the two
mechanisms, the expression of anchoring energy per unit area of
a projected plane of this grating surface is deduced and called
the equivalent anchoring energy formula. Both the strength and
the easy direction of equivalent anchoring energy are a function
of the geometrical parameters (amplitude and pitch) of a grating
surface. By using this formula, the grating surface can be
replaced by its projected plane and its anchoring properties can
be described by the equivalent anchoring energy formula. 相似文献
8.
The hysteresis loops, of Co films with thicknesses ranging from 12- to 80-monolayer-equivalent (MLE) coverages grown by thermal evaporation on a Cu-covered Si(111) surface, were measured in situ by the surface magneto-optic Kerr effect (SMOKE) technique. The hysteresis loops were measured as a function of Co coverage under an external sinusoidal magnetic field at fixed driving frequency. The coercivity Hc of the Co film versus thickness t followed a power law t−n with n=0.4±0.1 between 12 and 44 MLE, and stabilized after 44 MLE, up to the 80 MLE studied. The surface morphology of the 80-MLE Co film was imaged ex situ by atomic force microscopy (AFM) and scanning tunneling microscopy (STM), revealing cauliflower-like islands that were rough both in the short and long range. Analysis of the height–height correlation function for the largest image gave measurements of the effective roughness exponent (0.8), the vertical interface width w(2500 Å), and the lateral correlation length ξ(10 000 Å). We suggest that the coercivity changed in part due to changes in roughness of the Co films, deposited on a rough substrate; the spatial roughness would create an additional surface anisotropy, contributing to a fluctuation in the domain wall energy, resulting in a roughness-dependent coercivity. 相似文献
9.
XiaoYan Lu 《Journal of magnetism and magnetic materials》2010,322(15):2113-2116
Substrate thickness effects on the magnetization and magnetostriction of Terfenol-D films was studied by using a nonlinear constitutive model combined with the Timosheko elastic theory. Results show that characteristics of Terfenol-D films on compliant substrates are different from those of their bulk counterpart. Tunable properties can be obtained by adjusting the film/substrate thickness ratio. 相似文献
10.
11.
Time-dependent flow of a viscoelastic material through a wavy curved channel is studied. The flow traversing the wavy curved domain is modelled in the curvilinear coordinates. The viscoelastic fluid is described by the fluid relaxation and retardation times, and their variations are considered in relation to the flow characteristic time scale. The wavy walls of the curved channels are in sinusoidal form, with arbitrary phase difference. Using domain perturbation technique, the analytical solution of the model is obtained, including the velocity and the volumetric flow rate. The analytical solution is explained as a function of the flow domain structure, the viscoelastic fluid properties, and the flow generating force. Flow enhancement due to the flow domain is discussed; we have shown that the flow augmentation depends on the properties of the viscoelastic fluid. Furthermore, comparisons have been made with Newtonian fluid flow, and the prominent variations in the flow behaviours have been reported. 相似文献
12.
V. G. Sokolov D. D. Zhdanov I. S. Potemin A. A. Garbul A. G. Voloboy V. A. Galaktionov N. Kirilov 《Optical Review》2016,23(5):834-841
The article is devoted to elaboration of the method of reconstruction of rough surface scattering properties. The object with rough surface is made of transparent dielectric material. Typically these properties are described with bi-directional scattering distribution function (BSDF). Direct measurement of such function is either impossible or very expensive. The suggested solution provides physically reasonable method for the rough surface BSDF reconstruction. The method is based on Monte-Carlo ray tracing simulation for BSDF calculation. Optimization technique is further applied to correctly reconstruct the BSDF. The results of the BSDF reconstruction together with measurement results are presented in the article as well. 相似文献
13.
V. V. Kozlov I. D. Zverkov B. Yu. Zanin A. V. Dovgal V. Ya. Rudyak E. G. Bord D. F. Kranchev 《Thermophysics and Aeromechanics》2007,14(3):329-336
The development of velocity perturbations at laminar boundary-layer separation from a wing with wavy surface has been examined.
Experiments were carried out to identify flow features displayed by the spatially periodic flow structure. An analysis of
the linear stability of measured velocity profiles is performed. As a result of the analysis, the influence of surface waviness
on the frequency range and growth rates of instability waves was investigated, with a good agreement between calculated and
experimental data.
This work was supported by the Ministry of Education and Science of the Russian Federation under the Program “Development
of Higher-School Scientific Potential” for the years 2006–2008 (Projects RNP 2.1.1.471 and RNP 2.1.2.3370), and also by the
Russian Foundation for Basic Research (Grant No. 07-08-00164). 相似文献
14.
I. N. Pavlov I. L. Raskovskaya A. V. Tolkachev 《Journal of Experimental and Theoretical Physics》2017,124(4):570-579
Based on the refraction images of a droplet evaporating on a rough substrate, we simultaneously observed the dynamics of its surface microrelief, contact angle, and contact line deformations along the entire perimeter of the contact line. This has led us conclude that the microrelief structure is directly related to the phenomenon of contact angle hysteresis and the jump-like pattern of contact line deformation. We suggest a possible mechanism for the occurrence of contact angle hysteresis during droplet evaporation and derive the relations that specify the range of possible contact angles at known microrelief parameters. 相似文献
15.
A general theory, of second order in the film thickness and surface roughness over the wavelength, is developed of the optical properties of a thin film. These properties are described by a small number of electromagnetic constitutive coefficients. Formulae for these coefficients are derived in terms of the height-height correlation functions of the upper and lower surfaces of the film, and its average thickness. The reflectance, transmittance and ellipsometric coefficient are expressed in terms of the constitutive coefficients, for arbituary angles of incidence. 相似文献
16.
17.
A comparative analysis of hydrophobicity of fluoroalkylsiloxane and alkylsiloxane monolayers is presented. In order to compare wetting behavior on smooth and rough substrates, a simple model considering various self-assembly degrees of organic molecules and various area fractions of air inclusion is used. Sliding behavior for water on rough silanized needle-like surfaces is also evaluated. On smooth surfaces, regardless of assembly degree of coatings, contact angles of fluoroalkylsiloxane monolayers are always ∼10° larger. The difference, however, decreases when rough substrates with air inclusion are used. It is shown that assembly order of silane molecules and reduced water-solid contact area are the key factors leading to both high contact angles and low sliding angles. Such coatings are expected to be potential snow- and ice-repellent materials. 相似文献
18.
In this paper the directional hemispherical reflectivity and transmissivity of one-dimensional, randomly rough, dielectric surfaces are determined by the use of the integral method. This method is derived from electromagnetic theory without any restrictive hypotheses. Since this exact approach is computationally very intensive, a geometric optics approximation method is also developed. Curves displaying radiative properties versus the correlation length for a constant mean square deviation of the surface from flatness are presented. In this respect, the influence on the validity of the approximate method of multiple scattering, the shadowing effect and the real index of refraction of the dielectric have been investigated. Transverse electric and transverse magnetic polarized incident plane waves are considered. For the latter, our interest is focused on the influence of roughness on the reflected and transmitted intensities for an angle of incidence close to the Brewster angle. 相似文献
19.
《Waves in Random and Complex Media》2013,23(4):469-486
In this paper the directional hemispherical reflectivity and transmissivity of one-dimensional, randomly rough, dielectric surfaces are determined by the use of the integral method. This method is derived from electromagnetic theory without any restrictive hypotheses. Since this exact approach is computationally very intensive, a geometric optics approximation method is also developed. Curves displaying radiative properties versus the correlation length for a constant mean square deviation of the surface from flatness are presented. In this respect, the influence on the validity of the approximate method of multiple scattering, the shadowing effect and the real index of refraction of the dielectric have been investigated. Transverse electric and transverse magnetic polarized incident plane waves are considered. For the latter, our interest is focused on the influence of roughness on the reflected and transmitted intensities for an angle of incidence close to the Brewster angle. 相似文献
20.
E. E. Pestov D. V. Masterov A. E. Parafin S. A. Pavlov A. M. Klushin 《Physics of the Solid State》2017,59(11):2137-2142
HTS bicrystal junctions up to 50 μm wide on sapphire substrates have been studied. The dependences of the critical current on the temperature and external magnetic field of these contacts have been measured. The irradiation of the Josephson junction on a sapphire substrate at the frequency of 73 GHz at the temperature of 77 K resulted in the appearance of Shapiro steps in the current–voltage characteristic (IVC) at the voltage of 150 μV. The possibility of using such contacts in voltage standards at the temperature of 77 K in the ranges of microwave and terahertz frequencies has been analyzed. 相似文献