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961.
962.
963.
Experimental studies of the scattering of a monochromatic sound signal by a rough sea surface are carried out. The signal is produced by a point source in a shallow-water basin. The measurements are performed with the use of horizontal and vertical linear receiving arrays. The experimental data are compared with the estimates obtained on the basis of the model developed by the authors for resonant sound scattering by surface roughness. A satisfactory agreement between the experiments and the calculations is achieved. It is shown that the scattered signal is formed within small surface areas, whose sizes have the same order of magnitude as the first Fresnel zone with respect to the source and the receiving system. 相似文献
964.
H. K. Avetissian G. F. Mkrtchian M. G. Poghosyan 《Journal of Experimental and Theoretical Physics》2004,99(2):290-295
The relativistic quantum theory of cyclotron resonance in a medium with arbitrary dispersive properties is presented. The quantum equation of motion for a charged particle in the field of a plane electromagnetic wave and in the uniform magnetic field in a medium is solved in the eikonal approximation. The probabilities of induced multiphoton transitions between the Landau levels in a strong laser field are calculated. 相似文献
965.
A. V. Okotrub L. G. Bulusheva A. V. Gusel’nikov 《Journal of Experimental and Theoretical Physics》2004,99(6):1244-1252
A carbonaceous material containing single-wall carbon nanotubes (SWNTs) has been synthesized by arc-discharge evaporation of graphite with a catalytic additive of nickel and cobalt powders. The synthesized SWNTs were purified from an amorphous carbon component (soot) and the catalyst particles by boiling in nitric acid. A comparison of the X-ray fluorescence spectra measured before and after this treatment showed that acid etching significantly decreased the content of soot in the material. The material enriched with SWNTs is characterized by a reduced threshold for the appearance of the field emission current, which is explained by a decrease in the screening effect of soot. The current-voltage characteristics of SWNTs exhibit a hysteresis, which is suggested to be due to the adsorption of molecules and radicals on the surface and at the ends of carbon nanotubes. 相似文献
966.
A. A. Stanislavsky 《Journal of Experimental and Theoretical Physics》2004,98(4):705-706
An integrodifferential equation describing the angular distribution of beams is analyzed for a medium with random inhomogeneities. Beams are trapped because inhomogeneities give rise to wave localization at random locations and random times. The expressions obtained for the mean square deviation from the initial direction of beam propagation generalize the “3/2 law.” 相似文献
967.
The kinetics of current decay and partial restoration in planar doped GaAs:Si due to the formation of DX? centers in strong electric fields has been experimentally studied. The existence of thresholds with respect to the field strength and donor concentration is explained. A model of the DX? center formation is proposed, which is based on the notions about variation of the depth and width of a potential well created by planar doping, caused by the redistribution of hot electrons between quantum confinement subbands. As a result, the energy level of DX? centers, which is situated above the potential well depth in the absence of strong field, decreases and falls within the potential well. This makes possible the DX? center formation, provided that hot electrons, occupying the resonance electron levels in the conduction band, simultaneously excite local vibrational modes. 相似文献
968.
L. P. Babich 《Journal of Experimental and Theoretical Physics》2004,98(4):707-718
The collision operator of relativistic electrons with a cold gas of atomic particles is derived consistently taking into account elastic interactions, excitation of electron shells, and ionization. The creation of secondary electrons is described accurately. In the range of energies exceeding the binding energy of atomic electrons, the operator implicates only the angular scattering by nuclei and the ionization integral that automatically allows for scattering by atomic electrons. The collision operator used earlier for studying the kinetics of avalanches of relativistic runaway electrons is analyzed. A more exact operator derived in the present study is simpler in form and saves time in computer calculations. 相似文献
969.
970.
Results of a numerical analysis of mass transfer in systems of macroscopic particles with various isotropic interaction potentials are presented. Parameters that determine transport properties of nonideal dissipative systems are obtained for a broad class of model potentials. An approximate expression for the diffusivity of interacting particles is proposed. The relationship between diffusivity and viscosity is analyzed for strongly nonideal systems. 相似文献