Study of a Microwave Radar Signal Backscattered at Small Incidence Angles: In-Situ Measurements

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.     

Frequency characteristics of a linear two-mode laser with anisotropic coupled resonators

On the basis of the general method of calculation of linear weakly coupled anisotropic resonators, we obtained specific analytical expressions for the beat frequency between orthogonally polarized waves in resonators that contain a phase anisotropic plate in the active part and a polarizer in the passive part. We carried out experimental investigations. Good qualitative and quantitative agreement between theory and experiment is established. To whom correspondence should be addressed. Belarusian State Polytechnic Academy, 65, F. Skorina Ave., Minsk, 220027, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 4, pp. 565–568, July–August, 1999.     

Use of compression wave focusing for the production of a superjet

The principle of focusing compression waves by their reflection from nonflat surfaces is well-known. The invention in [1] postulates for this purpose the use in a pulsed hydrojet of a piston with a specially shaped surface. In this paper, the use of focusing is investigated numerically for the production of superjets.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 153–156, September–October, 1976.     

127I NQR spectra of iodoorganic compounds for diagnostic purposes

Theoretical and Experimental Chemistry -     

Determining the sea-roughness spectra from an optical image of the sea surface

An optical model of sea-surface imaging based on a two-scale presentation of sea roughness is developed. Using this model, an exact expression for the sea-surface image spectrum in diffuse sky light is obtained, which made it possible to estimate the nonlinear contribution of waves of different scales to the image spectrum. In particular, it is shown that the image spectrum is proportional to the wave tilt spectrum and the coefficient before the tilt spectrum is determined by the modulation of the short-wave contrast by long waves. Accuracy of determination of spectral contrasts of waves in surface-roughness anomalies (film slicks, internal-wave field, etc.) and accuracy of measurement of two-dimensional wave spectra from the sea-surface image spectrum are estimated. Examples of sea-roughness variability in the internal-wave field and examples of two-dimensional sea-roughness spectra are presented. All data were obtained by the optical method under full-scale conditions. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 1, pp. 53–63, January 2006.     

Slot diffraction of waves generated by an underwater explosion on the axis of a circular cylindrical shell

The problem of diffraction of a cylindrical shock wave generated by an electrical explosion in water on a longitudinal slot in a cylindrical rigid shell is considered. The numerical method of discontinuity breakdown is modified in relation to the polar coordinates used, which simplifies significantly the technical aspect of the solution. In the calculations pressure fields with diffraction maxima and minima are obtained and the evolution of the minima into ruptures is traced.Donetsk. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 6, pp. 3–8, November–December, 1996.