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141.
The numerical prediction of the fields of inelastic strains (the linear invariant of the tensor of inelastic strains) in thermoset polyester/marble filler composite plates is discussed. A uniformly distributed load is applied to the plates, which lie on a steel base. The strain fields are predicted by means of the boundary element method by using creep test data for the composites and the polyester matrix itself. Identical creep tests were performed for two ages of the materials (1 month and 13 years), which allowed evaluating the aging effect. The study is carried out in two stages. At the first stage, the application of the generalized Maxwell-Gurevich equation to the thermoset matrix/mineral filler composite is demonstrated. The model parameters determined from the experimental creep data is used for the second stage, where the state of inelastic strains in the plates is predicted by applying the boundary element method. The influence of composite formulation (filler content) and physical aging of the polyester matrix on the state of inelastic strains in the plates is shown.__________Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 41, No. 2, pp. 145–156, March–April, 2005. 相似文献
142.
Within the framework of microscopic fluctuation-dissipation theory, we obtain the stochastic equation describing the Brownian motion of an electron in the phonon field of the crystal lattice. An expression for the Green’s function of the phonon field is found in general form and for the case of linear phonon-variable interaction of an electron with the phonon field with allowance for the potential screening of crystal-lattice nuclei. An expression for the phonon drag acting on a conduction electron in the lattice field is found and analyzed with allowance for the interaction. Frequency dependence of the coefficient of the phonon drag acting on a conduction electron is studied and the contribution of the electron-phonon interaction to the effective mass of a charge carrier is determined.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 3, pp. 249–268, March 2005. 相似文献
143.
144.
本文提出从高分辨电子显微像中,利用光学、全息和部分相干等方法,提取传递函数,制作相位和振幅滤波器,实现解卷,提高高分辨电子显微像的分辨率. 相似文献
145.
A method of solving the problem of sound radiation from a plate with elements of different thickness in its plane is proposed, and the results obtained with this method are presented. It is shown that the main sources of sound radiation are the inhomogeneous flexural fields formed in the elements on both sides of their joint. 相似文献
146.
Amplitude equations, as well as the effective dispersion and nonlinearity parameters, which define the dynamics of a wave
packet formed by two strongly coupled modes, are derived with allowance for the frequency dependence of the linear mode coupling
coefficient. These equations are used to study the onset of the modulation instability of the two-mode wave packet, soliton-like
pulses, and compression modes. Unlike single-mode systems, the last two effects in optical waveguides may arise for both a
negative and positive disper-sion of the waveguide material. 相似文献
147.
G. Lujanienë 《Czechoslovak Journal of Physics》2003,53(1):A57-A65
In order to understand better the way in which radioactive contamination may be transferred from the atmosphere to other ecological compartments it is necessary to obtain information of the deposition mechanisms of radionuclides. Concentration and speciation of 137Cs and 7Be in the atmospheric aerosol and deposition were studied. The mixed deposition velocities of water-soluble and insoluble 137Cs and 7Be were determined. The relation between activity concentrations of insoluble 7Be in the atmosphere and its amount in deposition was observed. It is supposed that in the deposition process of radiocesium the precipitation plays an important role in scavenging of water-soluble radiocesium by falling raindrops, in contrast to insoluble 137Cs where the dry deposition becomes predominant. 相似文献
148.
The method of nonlinear moments, when used to solve the Boltzmann equation, necessitates the calculation of collision integral
matrix elements. The matrix elements are hard to calculate numerically, especially at large indices. The asymptotics of the
matrix elements are constructed. In terms of the model of pseudopower particle interaction, a formula free of summation is
derived. This makes it possible to find the asymptotic behavior of linear and nonlinear elements when two indices are large.
For an arbitrary interaction cross section, asymptotic expansions of linear and nonlinear matrix elements in one index are
obtained. For Maxwellian molecules, asymptotic formulas are derived for three large indices. 相似文献
149.
The fine-structure parameters of a series of configurations of the first ion of indium and the gyromagnetic ratios in intermediate coupling are calculated by a semiempirical method in the single-configuration approximation. 相似文献
150.
V. N. Popov 《Technical Physics》2003,48(5):541-545
The slip velocity of a rarefied gas nonuniform in temperature and mass velocity is calculated for gas slip over the surface
of a right circular cylinder. The calculation uses the two-moment boundary condition in an approximation linear in Knudsen
number. Corrections to the slip velocity that are due to the interface curvature, volume temperature stresses, and nonuniform
temperature distribution in the Knudsen layer are studied as func-tions of the accommodation coefficients in the first two
moments of the distribution function. The Bhatnagar-Gross-Krook model of the Boltzmann kinetic equation is employed as the
basic equation for the gas state. 相似文献