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991.
The excess electrical conductivity of an inhomogeneous superconducting film is calculated using a Random-Ginzburg-Landau model. Treating the quartic interaction within a self-consistent Hartree-approximation the excess conductivity of a random superconductor is found, for T ? Tc, to be enhanced compared to that of a homogeneous film. 相似文献
992.
The electrical conductivity, the Hall effect and the thermoelectric power in thec andb crystallo-graphic directions as a function of temperature on pure and doped ZnSb single crystals with hole conductivity were studied.The anisotropy of the hole mobility was explained on the basis of the anisotropy of the effective mass of holes in the crystallographic directions and the assumption of isotropic relaxation time. A model of the ZnSb valency band with two equivalent extremes was proposed which made it possible to explain the studied transport phenomena.The authors thank Mrs. V. Míková for preparing the ZnSb single crystals, Mr. J. Kapar for the crystallographic orientation and Mrs. J. Trepeová for her help in the experimental work. 相似文献
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996.
A systematic treatment of modifications to the usual form of dispersion relations and sum rules is given. The treatment is based on the fact that if a function g(z) has analyticity properties analogous to those of a scattering amplitudef (z), the usual dispersion relation for the productf (z)g(z) holds. After having described the general form of the weight function g(z) we concentrate on cases wheng(z) is large in a pre-chosen region and small elsewhere. Weight functions of this type are useful in practical applications where a weight functiong(z) may enhance a contribution of regions where accurate data are available and suppress those of regions with inaccurate or lacking data.Dedicated to Professor V. Votruba on his sixtieth birthday. 相似文献
997.
J. Šlechta 《Czechoslovak Journal of Physics》1968,18(10):1299-1308
On the basis of the classical theory of radiation produced in incomplete Coulomb interaction, a formula is derived for the coefficient of the bremsstrahlung of fully ionized plasma. In the region of rectilinear approximation a comparison is made with the results of the quantum formula derived from the Born approximation. Furthermore, the influence of dispersion upon the emission coefficient is taken into account; some relations for the region of dispersion are given. 相似文献
998.
For a Coulomb system contained in a domain Λ, the dielectric susceptibility tensor χ Λ is defined as relating the average polarization in the system to a constant applied electric field, in the linear limit. According to the phenomenological laws of macroscopic electrostatics, χ Λ depends on the specific shape of the domain Λ. In this paper we derive, using the methods of equilibrium statistical mechanics in both canonical and grand-canonical ensembles, the shape dependence of χ Λ and the corresponding finite-size corrections to the thermodynamic limit, for a class of general ν-dimensional (ν≥2) Coulomb systems, of ellipsoidal shape, being in the conducting state. The microscopic derivation is based on a general principle: the total force acting on a system in thermal equilibrium is zero. The results are checked in the Debye–Hückel limit. The paper is a generalization of a previous one [L. ?amaj, J. Stat. Phys. 100:949 (2000)], dealing with the special case of a one-component plasma in two dimensions. In that case, the validity of the presented formalism has already been verified at the exactly solvable (dimensionless) coupling Γ=2. 相似文献
999.
An improved calculation model for the prediction of levels of noise from trams is presented. The model is based on current calculation models for noise from trams and the measurements of equivalent noise levels from trams carried out in Kos?ice, Slovakia. The data were processed using correlation and regression analysis and besides already known factors (the number of tram sets passing a certain location per hour, tram speed, the type of tram rail, the tramline gradient), several new factors (wavelength of rail corrugations and rail grinding, the age of the tramcars and tramlines and the detailed composition of tram sets) have been included in the presented calculation model for the prediction of levels of noise from trams. 相似文献
1000.
M. Konč T. Švec A. Zeleňáková P. Sovák P. Kollár M. Kollárová 《Czechoslovak Journal of Physics》2002,52(2):195-198
We have investigated the structure (by TEM and SEM) and basic surface and bulk magnetic properties (by measurement of surface and bulk hysteresis loop and domain structure observations) of a Fe-Cu-Nb-Si-B/Fe-Nb-Si-B bilayer prepared by melt spinning method. We have detected perfect bonding between the two layers of the bilayered ribbon. This bonding produces tangential stress, which influences magnetic properties measured in surface layers at both sides of the ribbon. 相似文献