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251.
V. Yu. Karaev E. M. Meshkov G. N. Balandina E. M. Zuikova V. Yu. Gol'dblat V. I. Titov 《Radiophysics and Quantum Electronics》2005,48(8):587-598
We present the results of data processing of the field experiment devoted to a study of a microwave signal backscattered by
a rough water surface and compare them with the theoretical estimates. The measurements were conducted sequentially using
a radar with parabolic and knife-beam antennas. The radar was mounted on the Molitovsky bridge at a height of 40 m across
the Oka river in Nizhny Novgorod, Russia. For the radar with knife-shaped antenna pattern, we examined the reflected-signal
power and the shift and width of the Doppler spectrum as functions of the azimuthal angle for the nadir sounding. For the
parabolic antenna, we studied the reflected-signal power as a function of the incidence angle. Comparison with the experimental
data shows that the developed theoretical model of a Doppler spectrum is in good agreement with the observations.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 8, pp. 661–673, August 2005. 相似文献
252.
Valery V. Kiselev 《Central European Journal of Physics》2004,2(3):523-534
We calculate the leptonic constant for the pseudoscalar ground state of the B
c
meson in the framework of a QCD-motivated potential model taking into account the two-loop anomalous dimension for the heavy
quark current in nonrelativistic QCD as matched with full QCD. 相似文献
253.
254.
A nonlinear (in the cubic approximation) relaxation equation of state is derived for a rod containing cracks partially filled with an incompressible viscous liquid. The nonlinear effects of the self-action and interaction of low-and high-frequency longitudinal elastic waves propagating in such a rod are studied for the cases of identical and size-varied cracks. Linear and nonlinear acoustic parameters characterizing the self-action and interaction of elastic waves in a cracked rod are determined. 相似文献
255.
B.I. Sturman A.S. Gorkunova K.H. Ringhofer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(2):291-297
We investigate analytically and numerically the influence of the type of the photorefractive nonlinear response on the periodic
states (attractors) which occur during feedback controlled 2W-coupling and correspond to almost 100% diffraction efficiency
of the dynamic index grating. In addition to the case of the local response typical, for example, for LiNbO3 crystals we consider the cases of nonlocal (diffusive) response (BaTiO3, SBN) and resonant response (DC-biased BSO, BTO, and BGO crystals). It is shown that the conditions for the transition to
the periodic states and their apparent characteristics are strongly different for the two limiting cases above.
Received 16 July 2002 / Received in final form 29 October 2002 Published online 4 March 2003 相似文献
256.
V. A. Nadtochenko A. S. Lobach F. E. Gostev O. M. Sarkisov D. O. Shcherbinin E. D. Obraztsova 《JETP Letters》2004,80(3):176-180
The dynamics of the photoinduced differential absorption and excited-state bleaching spectra of single-walled carbon nanotubes suspended in a micellar solution were studied in the spectral range from 40 to 1000 nm within a time interval from 70 fs to 150 ps under excitation by 50-fs pulses with photon energies 2 and 4 eV. The bleaching and absorption bands were observed in the spectra; the positions of the bleaching peaks were independent of the photon energy of the exciting femtosecond pulse in the range 2–4 eV. It was established that, for delay times shorter than 1 ps, the shape of the differential spectrum of excited nanotubes coincided with the shape of the second derivative of the absorption spectrum of unexcited nanotubes in the frequency range of exciting pulse above 18000 cm?1 (the range of absorption bands of metallic nanotubes). In the frequency range below 16000 cm?1 (the range of absorption peaks of semiconducting nanotubes), the bleaching peaks in the differential spectrum of excited nanotubes undergo a high-frequency shift of 200–300 cm?1 with respect to the second-derivative spectrum of unexcited nanotubes. The excited-state relaxation rate constants were measured. They are well approximated by the exponential dependences and depend on the probe-pulse wavelength. An assumption was made about the nature of the observed spectra of excited nanotubes and about the excitation relaxation. 相似文献
257.
Photorefractive scattering occurs in rhodium-doped lithium niobate crystals irradiated by coherent light. The photorefractive scattering has both wide-angle and selective components. The results of experimental investigation of selective photorefractive scattering in LiNbO3:Rh crystals and calculation of the spatial structure of scattering are reported. The selective scattering is regarded as a kind of a frequency-degenerate fourwave vector interaction. 相似文献
258.
In order to study the influence of seeded impurities on ITER like reactor operation the COREDIV code has been extended to include the transport of several sputtered and/or injected impurities. In the COREDIV code the core plasma is treated in the frame of 1D radial transport model whereas in the edge the 2D multifluid code EPIT is used. The EPIT code solves in the slab geometry the MHD equations for densities and velocities for all ions species as well as for electron and ion temperatures. The iteration scheme in the code leads to steady state solution of coupled core and SOL system. The numerical results for Carbon and Nickel plate and seeded impurities Silicon and Neon are presented. 相似文献
259.
This paper deals with a singular perturbation of the stationary Stokes and Navier-Stokes systems. The term ε2Δp is added to the continuity equation, where ε is a small parameter. For a domain with cylindrical outlets to infinity and exponentially decaying data, existence and uniqueness of solutions under flux conditions at infinity are established for the linear problem and also for the nonlinear problem in the case of small data. Asymptotically exact estimates are proved for ε tending to zero. For sufficiently regular data, these estimates imply the convergence in H
loc
5/2−δ
for the velocity parts and in H
loc
3/2−δ
for the pressure parts, respectively. Bibliography: 17 titles.Dedicated to V. A. Solonnikov on the occasion of his 70th birthday__________Published in Zapiski Nauchnykh Seminarov POMI, Vol. 306, 2003, pp. 107–133. 相似文献
260.