Volume 62, Nº 1 (2017)

The effect of the generation of stimulated Raman scattering in monoclinic niobate LaNbO₄, which is known as a base crystal for lasant ions Ln³⁺, has been discovered. The χ⁽³⁾ nonlinear Stokes and anti-Stokes biphonon lasing of this niobate has been studied under picosecond excitation.

The nature of the magnetocaloric effect (MCE) in compounds R₂Fe₁₄B (R = Nd, Er) and their hydrides in a wide temperature range is investigated. The investigation is carried out on initial samples of a special purity including single-crystalline ones. The highest value of the magnetocaloric effect is established in the Curie-temperature region. The hydrogenation of samples affects the value of the MCE. The model explaining the dependence of the value and sign of the magnetocaloric effect on the hydrogen contents in R₂Fe₁₄B compounds with participation of erbium and neodymium is proposed.

The purpose of this investigation is quantitative determination of deformational changes in the ice structure immediately upon displacement under conditions of high hydrostatic pressure by the method of acoustic emission and estimation of the effect of the structure on the ice−substrate adhesive bond strength. The relation between the reciprocal acoustic compliance of ice, the size of mobile elements of its structure, their resonance eigenfrequency, and the density is established. The model is verified. The correlation of the amplitude−frequency spectra of the acoustic emission on the frictional contact with the acoustic spectra of eigenvibrations on glaciers from remote sources is confirmed. The results obtained can be used for distant study of the modes of motion of ice in glaciers.

The Kowalewski exponents in the problem on the motion of a solid under the Chaplygin condition are calculated (when there is a velocity-linear invariant relation). The method of calculation uses the generalizing Ioshida theorems on the Kowalewski exponents found by V.V. Kozlov. It is shown that the general solution of the equations of motion branches out in the complex time plane under the Chaplygin conditions.

The states of a linearly elastic micropolar body in which there are pure couple stresses are studied, while the force stresses are zero. The plane and spherically symmetric problems are investigated for a micropolar body under conditions of quasi-solid states. The obtained solutions can be useful for experimental determination of the moment constants of micropolar media.

An approach for level-by-level analysis is considered, and models for corrected investigation of stress-strain states in layers of generally irregular three-layer conical shells are developed on its basis. The models make it possible to take into account the features of a layer-inhomogeneous structure, the moment state of carrying layers, and the three-dimensional stressed state in the filler layer.

It is shown that for Mindlin media with fields of defects there is an alternative interpretation allowing to describe the material affected by defects as equivalent functionally-gradient material with varying properties for coordinates, modeled in the classical theory of elasticity. We establish clear relationships for determining the properties of functionally graded materials by the solutions, taking into account the availability of fields of defects. It is shown that, in general, the properties of equivalent functionally-gradient material depend on the coordinates, as well as on the loading and boundary conditions.