R e g u l a r p a p e r s

Moscow University Physics Bulletin 1977. **32**. N 5. P. 10

A model of a thermal control enamel-ceramic type surface coating damaged by impact of streams of charged particles is presented, and a procedure is proposed for calculating changes in coating reflectivity. The limits of applicability of the proposed method, and errors inherent in the method, are discussed. Conclusions are drawn on the feasibility of calculating the behavior of the spectral reflectivity of thermal control coatings during laboratory testing and field tests.

Show AbstractMoscow University Physics Bulletin 1977. **32**. N 5. P. 18

A brief survey is presented of mathematical models of the topography of rough surfaces, a statistical survey of which can be described with the aid of distribution functions of heights and inclination angles of the faces when the mean height of asperities and the mean angle of inclination of faces are specified. A simplified model is proposed to account for diffuse reflection of electromagnetic waves from rough surfaces. The dependence of the scattered radiation field on the geometrical and optical characteristics of the surface topography, angle of incidence, wavelength, and interaction scale of interacting wave and reflecting surface is presented.

Show AbstractMoscow University Physics Bulletin 1977. **32**. N 5. P. 27

Moscow University Physics Bulletin 1977. **32**. N 5. P. 35

Interaction between the velocity field and turbidity field of a suspensionladen stream is examined on the basis of statistical identification of dynamical systems. It is shown that the amplitude-frequency response of the velocityturbidity system presents additional information on the effect of stream velocity fluctuations on turbidity fluctuation at different frequencies.

Show AbstractMoscow University Physics Bulletin 1977. **32**. N 5. P. 41

It is shown that the amplitude of standing gravitational waves in the interior of a spherical resonator cavity is a whole order of magnitude greater than the amplitude of a gravitational wave in a concentric resonator. Expressions are derived for the gravitational field components, and several limiting cases are investigated. Calculations are performed with exact account taken of time lag. The effect of the surroundings on the process of radiation of standing gravitational waves is discussed.

Show AbstractMoscow University Physics Bulletin 1977. **32**. N 5. P. 46

A formula is derived for the pressure in a system with three - particle interaction via binary and three - particle distribution functions, and on that basis thermal and caloric equations of state of the crystal are derived, jointly with a formula for the mean value of the energy, accurate to the order of collective vibrations.

Show AbstractMoscow University Physics Bulletin 1977. **32**. N 5. P. 53

The existence of Poincare periodic solutions in the problem of planar translational- rotational motion of two rigid possessing a common plane of dynamical symmetry is proved. Qualitative and numerical analysis of analytical conditions of the existence of periodic solutions is carried out. The discussion covers synchronous motion of two similar ellipsoids.

Show AbstractMoscow University Physics Bulletin 1977. **32**. N 5. P. 60

A phenomenological description of three-photon dipolar and quadrupolar scattering from density fluctuations in an Isotropic medium, analogous to the thermodynamic theory of two-photon scattering done in Ref. [15], is carried out. The equations obtained describe the angular distribution and the polarization properties of the scattered light. It is shown that in the case of scattering by a gas only the quadrupolar scattering takes place, and its intensity is expressed in terms of molecular quantities. A numerical evaluation of the intensity is performed, and the possibility of observing the effect experimentally is discussed briefly.

Show AbstractMoscow University Physics Bulletin 1977. **32**. N 5. P. 65

The root locus method is employed in investigating automatic control systems containing a distributed oscillatory component. Basic equations are derived for the loci. Reduction of the fundamental system to a lumped - parameter automatic control system is discussed.

Show AbstractMoscow University Physics Bulletin 1977. **32**. N 5. P. 71

An approximate method is developed for calculating averages with the aid of a relativistic Oort distribution function for gravitating particles with cylindrical symmetry. Accuracy estimates are obtained for the method. The relativistic Oort formula is derived for the dependence of the mean velocity of the particles on the distance to the rotation axis, and this formula is in agreement with results of nonrelativistic statistics for low velocities ϑ≪c. The relativistic particle number density, the component of the mean velocity 4 - vector, and the momentum - energy tensor are calculated. The relativistic particle number density coincides with the familiar barometric formula for low velocities ϑ≪c and for low potentials Ф≪c^2. Reliance on Eckart phenomenological yields equations of state which coincide in the relativistic limit with the equations of state of an ideal gas.

Show AbstractMoscow University Physics Bulletin 1977. **32**. N 5. P. 76

The mean occupation number of some state in the forbidden band in a disordered semiconductor illuminated by light is found in the one - electron approximation. If the matrix element of the dipolar interaction with the light is less than the level broadening caused by the electron - phonon interaction, the effect of light on the collision processes can be neglected. In this approximation, the small corrections to the Fermi distribution function are found: aconstant, and a term which fluctuates in time with double the frequency of the light. It is shown that the second is smaller than the first if the width of the levels is smaller than the energy of the photon. The expression for the time - independent correct ion can be put in the form of a balance equation havinga clear physical sense.

Show AbstractMoscow University Physics Bulletin 1977. **32**. N 5. P. 84

On the basis of previously derived simplified equations the performance of a nonlinear dielectric resonator in a microwave regenerative parametric amplifier is analyzed. Expressions are derived for the threshold power of the self - excitation and for the band width of such an amplifier.

Show AbstractMoscow University Physics Bulletin 1977. **32**. N 5. P. 90

The effect of scattering into side valleys on the conductivity of a semiconductor when electrons are warmed up by a RP field is discussed. It is shown that the field dependence of the conductivity has a droop interval under certain conditions.

Show AbstractMoscow University Physics Bulletin 1977. **32**. N 5. P. 97

A model scheme Is examined for separate measurements of the magnitudes of the real and imaginary parts of the cross-spectral density of stationary coupled random processes. The use of heterodyne multiplication with preliminary filtering of the signals significantly simplifies the measuring scheme of the spectral characteristics. The use of hard clipping of the signals after preliminary filtering is considered, which leads to theoretical and technical advantages. In this work the exact characteristics of the described schemes are evaluated.

Show AbstractB r i e f r e p o r t s

Moscow University Physics Bulletin 1977. **32**. N 5. P. 105

Moscow University Physics Bulletin 1977. **32**. N 5. P. 108

Moscow University Physics Bulletin 1977. **32**. N 5. P. 110

Moscow University Physics Bulletin 1977. **32**. N 5. P. 114

Moscow University Physics Bulletin 1977. **32**. N 5. P. 117

Moscow University Physics Bulletin 1977. **32**. N 5. P. 119