Faculty of Physics
M.V.Lomonosov Moscow State University

## Investigation of the dynamical properties of a fourth-oder system with one limiting point by the root-trajectory method

### G.A. Bendrikov, V.I. Miftakhov

Moscow University Physics Bulletin 1982. 37. N 3. P. 1

The family of root trajectories of a fourth-order system with the characteristic equation(a$_0$p$^{4}$+a$_1$p$^3$+a$_2$p$^2$+a$_3$p+a$_4$+K(b$_0$p+b$_1$)=0 is investigated. Having determined the types of root trajectory, their analysis leads to the establishment of general properties, allowing calculations of such systems to be more expediently performed.

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## Radial distribution of Xe atoms in the positive column of a glow discharge in an He—Xe mixturе

### L.M. Volkova, A.M. Devyatov, E.A. Kral'kina, L.V. Shibkova

Moscow University Physics Bulletin 1982. 37. N 3. P. 8

In plasma of a helium-xenon discharge, the radical distribution of xenon atoms due to cataphoresis is investigated as a function of the partial pressures of helium and xenon, the discharge current, and the distance from the cathode. The experimental results are compared with theoretical calculation.

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## Uniqueness of determining a heat source from indirect data

### V.В. Glaskо, Е.Е. Коndоrskауа, Sh.M. Вidzinоv

Moscow University Physics Bulletin 1982. 37. N 3. P. 13

The problem considered is the uniqueness of determining a heat source from minimal information on the temperature field outside the region that it occupies, when either or both of the intensity and the region of localization are unknown (in R$_{2}$). The problem is formulated for different stages of development of the source. Theorems for a point source (various cases) and also for a distributed source of uniform intensity with a given localization region are given.

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## Optical appearance of the inhomogeneous broadening of the electrons spectra of liquid dye solutions

### L.V. Levshin, B.D. Ryzhikov, N.R. Senatorova

Moscow University Physics Bulletin 1982. 37. N 3. P. 17

The nature of the changes in absorption spectra of a series of dyes occurring in mixed polar solvents is discussed. The data obtained are interpreted as the appearance of inhomogeneous broadening of the electronic absorption spectra. The relation between the dependence observed and the luminescent characteristics of the investigated materials is demonstrated.

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## Evolution of the orbits of the components of a triple star system

### A.A. Оrlоv, N.A. Sоlоvауa

Moscow University Physics Bulletin 1982. 37. N 3. P. 22

The evolution of the orbits of the components of a triple star system is considered. For the example of the triple system £ Aqu, the importance of determining the sign of the inclination of the orbits of the triple- star components is demonstrated. At certain values of the inclination, the possibility of close approach of internal-pair stars is created periodically over time.

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## Point-defect formation in the nonconservative motion of dislocations under the action of a sign-variable load

### Yu.A. Ivashkin

Moscow University Physics Bulletin 1982. 37. N 3. P. 27

The features of the mechanism of point-defect formation in the nonconservative motion of dislocations with steps under the action of a sign-variable load in alkali-halide crystals is considered. Within the framework of the model, taking account of vacancy emission by steps on spiral dislocations and of vacancy absorption by dislocations, an experimental dependence of the excess vacancy concentration on the amplitude of the mechanical stress at the initial stage of deformation is found.- It is shown that, at the stage of linear strengthening, the excess vacancy concentration must reach saturation.

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## Appearance of shock waves in a shock tube when a diaphragm bursts

### L.S. Shtemenko

Moscow University Physics Bulletin 1982. 37. N 3. P. 32

The appearance in a shock tube of weak shock waves that interact to form a basic shock wave is investigated. It is shown that, in a gas that is under propulsion, both acoustic perturbations (M = 1) and weak shock waves (M = 1.03-1.40) are produced by the propellant. The first arise when a flow of propellant gas passes around the sharp edges of a bursting diaphragm and the second arises in the motion of a region of finite density change behind the front of the second nonsteady shock discontinuity. The Mach machine of the basic shock wave varies from 1.5 to 3.

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## Generation of electromagnetic waves by gravitation waves in electric and magnetic fields

### V.I. Grigoriev

Moscow University Physics Bulletin 1982. 37. N 3. P. 39

A theoretical investigation is made into the intensity, spectral composition, and angular distribution of the electromagnetic radiation arising when a plane gravitational wave passes through an electric or magnetic quasistatic field.

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## Magnetic splitting of the nonlinear resonance in the three-level system Ar II

### N.A. Glavatskikh, L.E. Grin, V.V. Lebedeva, A.I. Odintsov

Moscow University Physics Bulletin 1982. 37. N 3. P. 44

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