共查询到20条相似文献,搜索用时 15 毫秒
1.
A method is proposed for improving the accuracy of measuring the wedge angle of transparent plates using a lateral-shear holographic
interferometer. Consecutive processing of a pair of interferograms with doubled number of interference fringes leads to reduction
of the observational error by a factor of two compared to traditional interferometric methods. Data on the experimental validation
of the method are presented. 相似文献
2.
The distributions of zeros of the partition function of lattice gas models of Fisher (at some temperature) and of Temperley are obtained. The former is a closed loop crossing the real axis and the latter is a part of the negative real axis. 相似文献
3.
A. Yu. Gufan O. V. Kukin Yu. M. Gufan 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(5):661-665
It is widely known that the interaction of triplets of particles (which are not reducible to the sum of pair interactions)
play an important role in formation the nonlinear and anisotropic properties of crystals. The aim of this work is to establish
a general form of the dependence of these properties on interactions of triplets of atoms that is dependent only on the structure
of the crystals. To separate the interactions of triplets of atoms from those of quadruples, we assume that the energy of
triplets of interacting atoms depends only on the characteristics of a triangle whose vertices are the centers of gravity
of interacting atoms. In this model, the internal energy must therefore be invariant upon rearrangement of the numbers of
interacting atoms and any rotation of the triangle in isotropic space, P(3) × O(3). To specify the form of energy dependence on characteristics of selected triangles, we constructed an integral rational
basis of invariants in dependence on the components of the vectors connecting the vertices of each triangle. Using the example
of a simple dependence of the energy on basic invariants, we show how to move from the assumed energy dependence on invariants
to the dependence of energy on lattice sums. 相似文献
4.
A. V. Matveev 《Russian Physics Journal》2007,50(7):646-652
Within the framework of the electron density functional, a technique is developed for calculation of the adsorption energy
and variation in the electron work function for metal substrates due to metal atom adsorption. The corrections to the local
density approximation, which are associated with non-uniformity of the electron density in the subsurface region and discontinuous
ion charge distribution over the crystal lattice sites, are included into consideration. It is shown that adsorption of alkali
metal atoms results in lower electron work function, while that of transition metals (cobalt, iron, and chromium) might both
decrease and increase the electron work function. Formation of a variety of adsorption structures from metal atoms depending
on the temperature is discussed.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 14–19, July, 2007. 相似文献
5.
The specific features revealed in the superlinearity of dose dependences of thermoluminescence of anion-defective aluminum oxide single crystals have been considered theoretically in terms of the model of an interactive trap system. The model explains the decrease in the degree of superlinearity at a low heating rate, as well as with an increase in the dose increment, the occupancy of deep traps, and the sensitivity of the crystals to radiation due to the increase in the concentration of luminescence centers. The obtained results indicate a widening of the possibilities of the model for interpreting experimental data in the investigation of the dose characteristics of thermoluminescence of the studied crystals. 相似文献
6.
E. T. Shavgulidze 《Russian Journal of Mathematical Physics》2009,16(1):130-132
The amenability of several discrete subgroups of the group of diffeomorphisms of the circle is proved. 相似文献
7.
A. H. Martirosyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2009,44(6):296-299
A new method for determining the density of polymer materials based on determination of the path-length differences in moiré
patterns is proposed. The method is characterized by simplicity and accuracy of results. The densities of polychloropren and
polystirol have been determined with high accuracy. Knowledge of the dependence of the polymer density on the stretching degree
enables one to reveal the dynamics of changes in the permolecular structure at deformation of polymers. 相似文献
8.
New methods of interpretation of meteor observations were developed and published in [1?C9]. The interpretation of ground-based observations of meteors and bolides available today in the scientific literature all over the world suffers from serious contradictions. Observers use the so-called photometric approach for determination of extra-atmospheric masses of meteoric bodies. This approach is based on the formula proposed in 1933 [10] and very simple ideas of how to describe the interaction between the atmospheric air and the surface of a meteoric body. These ideas are provisionally suitable to describe the flow around a body in a free molecular regime. Subsequently, the photometric approach was applied to all the meteor events including bolides. The main effort aimed to elaborate the approach included a choice of new formulas for the radiative efficiency. 相似文献
9.
N. K. Choudhury 《Zeitschrift für Physik A Hadrons and Nuclei》1958,151(2):93-105
The polarization ratio (I b/Ia) of fluorescence of a monocrystalline film of pure anthracene is measured correcting for all probable errors. Comparison with decay-time data brings out that deviation from the value obtained from absorption measurements is due to a loss of intensity in the a-polarized fluorescence as compared to what is expected from absorption data. This is interpreted as an evidence that anthracene crystal fluorescence is emitted from regions of local lattice imperfections. It is confirmed that the first electronic transition takes place along the short axis of the anthracene molecule. 相似文献
10.
The features of the macroscopic inhomogeneity of plastic deformation in the form of autowaves with a pulsating amplitude are analyzed, and data on the localization of sources of acoustic emission at different stages of plastic flow in the stretching of fcc mono- and polycrystals are presented. The relationship between the local components of the plastic distortion tensor in the strain localization zone is traced. The role of acoustic phenomena accompanying the localization of plastic strain in the development of the process of plastic deformation is considered. 相似文献
11.
This paper studies the symmetry of Lagrangians of
nonholonomic systems of non-Chetaev's type. First, the definition
and the criterion of the symmetry of the system are given. Secondly,
it obtains the condition under which there exists a conserved
quantity and the form of the conserved quantity. Finally, an example
is shown to illustrate the application of the result. 相似文献
12.
Russian Physics Journal - A mathematical model of the flow of aggregated load characteristics of network traffic data packets in the form of a set of analytical signals is proposed. The real parts... 相似文献
13.
14.
L. S. Lunin B. M. Sinel’nikov I. A. Sysoev 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2018,12(5):898-901
The effect of an argon ion beam on the surface of sapphire is studied at different technological parameters: the ion energy, and the angle α between the sapphire surface and the ion-beam axis. The roughness of the sapphire surface is analyzed before and after ion polishing. The optimum ion-beam parameters are determined, at which the surface roughness after polishing decreases to 0.8 nm. At angles α = 20°–30°, the relief of the sapphire surface is found to become wavy. The study of the impact of the ion energy on the roughness of the sapphire surface in the 400–1200-eV range reveals that an increase in the energy of the ion beam to 1200 eV is accompanied with a decrease by 8.8 times in the roughness which falls below the level of 3 nm. 相似文献
15.
A. A. Sobko 《Doklady Physics》2018,63(5):186-188
General considerations on the form of the real equation of state make it possible to assume that the ratio of the melting temperature to the critical temperature is constant for each group of elements. This assumption is verified for two groups of elements, the critical temperatures of which are measured. It is shown that, for certain groups of elements, the critical temperatures of which are calculated instead of being measured, this assumption is also valid. The critical temperatures of certain elements are calculated or refined. 相似文献
16.
The frequencies of the harmonic vibrations of 88 compounds consisting of atoms of the first period are calculated in the approximation of the hybrid density functional B3LYP with the 6-31G* basis set. Using 1189 frequencies from experimental IR and Raman spectra of these compounds in the gas phase and the corresponding theoretical frequencies, the coefficients of the function of linear scaling are found by the least squares method. The method of linear scaling of frequencies is applied to the prediction of the 108 vibrational frequencies of a porphin molecule. A conclusion is made that this method is promising for the interpretation of vibrational spectra of complex molecules and, in combination with the Pulay method of scaling of a quantum-mechanical field, for the determination of harmonic force constants. 相似文献
17.
Based on the analysis of the experimental data on the observation of the fluorescence and superradiance of praseodymium ions in a matrix of lanthanum trifluoride, a model of superradiance of three-level radiators with two close upper levels is developed in the mean-field approximation and studied. The uppermost level is coherently pumped by an ultrashort pulse of electromagnetic field, after which the excitation is transferred to the close energy level, from which the superradiance transition occurs to the lower level. In limiting cases, the considered model is reduced to the known models of superradiance and describes the ordinary regimes of monopulse and multipulse (oscillatory) superradiance. However, in a certain region of parameters, the model under discussion describes such a multipulse superradiance signal in which electromagnetic field spikes composing it follow in time with random intervals and amplitudes, so that the regime of regular chaotic dynamics is demonstrated in a single superradiance signal. In a certain time interval, the proposed model can be described by the Lorenz equations with the parameters corresponding to the chaotic dynamics of spikes composing the superradiance signal. The presented results of the numerical simulation of the model equations qualitatively correspond to the picture of stochastic pulsations observed experimentally. 相似文献
18.
We consider two classes of probability distributions for configurations of the ideal gas. They depend only on kinetic energy and they remain of the same form when degrees of freedom are integrated out. The relation with equilibrium distributions of Tsallis’ thermostatistics is discussed. 相似文献
19.
多介质流体动力学过程的数值模拟往往涉及混合物状态方程的计算. 做图法和Newton 法是混合物状态方程计算常采用的方法, 前者虽直观精度却差, 后者计算效率高却只具有局部收敛性, 当解与其初始猜测值相差较远时Newton法不一定能够获得收敛解. 为此, 本文给出一种具有大范围收敛性的嵌入算法(imbedding method)求解混合物状态方程, 其基本思想是通过引入嵌入参数, 将待解的混合物状态方程和易解的混合物状态方程线性组合, 构成嵌入方程组, 当嵌入参数从0连续地变化到1 时, 嵌入方程组的解由易解的混合物状态方程的解连续地变化为待解的混合物状态方程的解. 嵌入方程组可由Newton法迭代求解, 也可转化为以嵌入参数为自变量的常微分方程组, 从而易于由成熟的计算方法如梯形法等进行求解. 进一步利用热力学基本关系, Maxwell形式的微分方程描述了压力和温度随嵌入参数的演化速率与应变速率和组分质量分数演化速率的关系. 对铅锡混合物热力学量的计算表明了本文算法的有效性. 相似文献
20.
Using time-resolved high-speed shadowgraphy, the dynamics of phenomena due to laser-based lithotripsy is studied. Collapsing mechanism of bubble formed therein is investigated. In order to study the mechanism, the optically implemented mathematical morphology is applied. The study of the shape of the plasma and the collapsing region of the bubble of fluid that we are studying can possibly be used for practical application for laser-based lithotripsy. 相似文献