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991.
A. T. Barabanov 《Journal of Mathematical Sciences》1998,90(6):2537-2540
We propose criteria for controllability and observability of stationary systems specified by complex domain models. Conclusions
concerning controllability and observability are made on the basis of coefficients in the corresponding transfer functions.
Translated fromDinamicheskie Sistemy, Vol. 12, pp. 120–126, 1993. 相似文献
992.
Yu. G. Abov D. S. Denisov N. O. Elyutin S. K. Matveev Yu. I. Smirnov A. O. Éidlin F. S. Dzheparov D. V. L’vov 《Journal of Experimental and Theoretical Physics》1998,87(6):1195-1200
The asymptotic behavior of the spectra for large values of the scattering vector for the case of elastic multiple small-angle
neutron scattering (SANS) is investigated theoretically and experimentally. An expansion of the spectrum in terms of the reciprocal
of the magnitude of the momentum transfer is obtained taking account of the influence of the instrumental line. It is shown
that, to within some factor, the leading term of the expansion is identical to the differential single-scattering cross section
averaged over a statistical ensemble of particles; several subsequent terms in the expansion are calculated and the range
of applicability of the resulting expressions is determined. The asymptotic behavior of the multiple SANS spectrum is measured,
using a two-crystal neutron spectrometer, for samples of an HTSC ceramic, the alloy Fe-Ni, and Al powder. The agreement between
the experimental results and the theoretical predictions is analyzed.
Zh. éksp. Teor. Fiz. 114, 2194–2203 (December 1998) 相似文献
993.
We propose a method for deriving duality relations for two-dimensional inhomogeneous Z(N)-symmetric models on a finite square lattice wound around a torus. The method is used to obtain duality relations for the
vector Potts model, the Berezinskii-Villain Z(N)-model, the Ashkin-Teller model, and the 8-vertex model on a lattice obliquely wound around a torus, as well as an exact
relation linking the partition functions of the latter two models.
Zh. éksp. Teor. Fiz. 113, 240–260 (January 1998) 相似文献
994.
A. P. Zhernov 《Physics of the Solid State》1998,40(10):1658-1660
The linear thermal expansion coefficient of crystal lattices of germanium with different isotopic compositions is analyzed.
Fiz. Tverd. Tela (St. Petersburg) 40, 1829–1831 (October 1998) 相似文献
995.
M. A. Korzhuev 《Physics of the Solid State》1998,40(2):204-205
It is shown that the entropy of crystallization of materials (such as Cu, Ag, Au, and Li) in a “molten” sublattice of superionic
conductors→crystal system may substantially exceed the entropy of crystallization of the same materials from a melt. The observed
behavior explains the known tendency of various superionic conductors to form filamentary crystals (whiskers) in the solid
phase, together with the completely different structure of these whiskers.
Fiz. Tverd. Tela (St. Petersburg) 40, 227–228 (February 1998) 相似文献
996.
Time-resolved photoluminescence from porous silicon coated with a diamondlike carbon film is investigated. The intensity of
the photoluminescence from the carbon film is obserd to increase after deposition, and there is an accompanying change in
the intensity and a shortwavelength shift of the photoluminescence band of porous silicon that depends on the porosity of
its original layers. These changes are explained by the formation of carbon nanoclusters on the surface of the silicon filaments.
Zh. Tekh. Fiz. 68, 83–87 (April 1998) 相似文献
997.
S. A. Kazantsev N. M. Firstova L. K. Kashapova A. V. Bulatov A. G. Petrashen' 《Russian Physics Journal》1998,41(12):1258-1262
Polarization data are given for three whiskers recorded with the large solar vacuum telescope at the Baikal Observatory, Institute
of Solar-Terrestrial Physics, Russian Academy of Sciences. The observed degree of polarization varies from 2 to 13%. The direction
of the polarization plane for the mediumintensity whisker was tangential, while that for the weakest one was radial. The brightest
whisker had the polarization plane direction close to radial at the center of the line but tangential at the flanks. It is
assumed that the polarization is due to impact excitation of a hydrogen-atom ensemble in the solar chromosphere by an electron
beam, and estimates are made of the beam energy.
St. Petersburg Fine Mechanics and Optics Institute, St. Petersburg. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii,
Fizika, Vol. 41, No. 12, pp. 85–89, December 1998. 相似文献
998.
We set up model transport equations that describe the behavior of molecular (diatomic and polyatomic) gases with a molecule
collision rate proportional to the molecular velocity. In deriving these equations we allow for the internal (rotational)
degrees of freedom, while the vibrational degrees of freedom are assumed “frozen.” We also set up an exact equation for the
problem of the temperature jump with allowance for slow evaporation from the liquid surface into the saturated vapor atmosphere.
Finally, we derive explicit formulas for calculating the coefficients of the temperature jump and gas-density jump above a
flat surface and do the necessary numerical calculations.
Zh. éksp. Teor. Fiz. 114, 956–971 (September 1998) 相似文献
999.
B. Dubrulle F.-M. Bréon F. Graner A. Pocheau 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,4(1):89-94
We consider fields which take random values over several decades. Starting from physical examples, we postulate that scale is not an absolute quantity. We then establish the equivalence between two existing approaches based on scale symmetry arguments as general as possible.
This yields a classification of log-infinitely divisible laws, possibly universal. The physical significance of the parameters
entering in the classification is discussed.
Received: 7 November 1997 / Received in final form: 26 March 1998 / Accepted: 30 March 1998 相似文献
1000.
A statistical approach including direct correlation functions is applied to study the influence of the surface confining the
nematic liquid phase on the Franck elastic coefficients. Specific calculations are made for a model system composed of ellipsoidal
molecules interacting by means of the Gay-Berne potential near the interacting surface.
Fiz. Tverd. Tela (St. Petersburg) 40, 1356–1359 (July 1998) 相似文献