Structure, magnetic, and electric properties of bismuth niobates doped with d -elements: V. Magnetic and electrophysical properties of copper-containing solid solutions with the structure of bismuth niobate, Bi5Nb3O15

Magnetic susceptibility and electrophysical properties of copper-containing solid solutions with the structure of bismuth niobate, Bi₅Nb₃O₁₅, were studied. Paramagnetic aggregates (dimers) of copper atoms are formed in the solid solutions, their fraction substantially exceeding the statistically probable value. The parameters of exchange interactions in the dimer clusters of copper atoms and the distribution of monomers and dimers in the solutions were calculated. The exchange parameter of antiferromagnetic interactions between copper atoms in the dimers is −210 cm⁻¹. Original Russian Text ? N.A. Zhuk, I.V. Piir, A.L. Pimenov, N.V. Chezhina, 2008, published in Zhurnal Obshchei Khimii, 2008, Vol. 78, No. 3, pp. 353–357. For communication IV, see [1].     

Dynamics of particles near a plane boundary in the radiation field of an acoustic wave

The problem of interaction of a rigid body and a boundary of a viscous fluid under acoustic wave propagation is investigated. An example of the motion of a cylinder in the vicinity of a flat rigid wall caused by acoustic field forces is examined. S. P. Timoshenko Institute of Mechanics, National Academy of Sciences of Ukraine, Kiev. Translated from Prikladnaya Mekhanika, Vol. 35, No. 10, pp. 74–79, October, 1999.     

State estimation for a dynamical system described by a linear equation with unknown parameters

We investigate the state estimation problem for a dynamical system described by a linear operator equation with unknown parameters in a Hilbert space. In the case of quadratic restrictions on the unknown parameters, we propose formulas for a priori mean-square minimax estimators and a posteriori linear minimax estimators. A criterion for the finiteness of the minimax error is formulated. As an example, the main results are applied to a system of linear algebraic-differential equations with constant coefficients.     

Approximating periodic functions by interpolation sums of Jackson type

Let

Regularities of adhesive failure in particulate filled polymers

The effect of adhesion between matrix and filler on mechanical properties of composites is analyzed. It is shown, that the loss of adhesion (extension of exfoliated surface) leads to a marked reduction of uniaxial tension modulus. Regularities of interphase crack growth were found and dependences of initial (critical) and final angles of exfoliation upon mechanical and scale factors were obtained.     

Boundary-condition transformation in problems of electromagnetic-wave scattering by an uneven impedance surface

A rigorous method is developed for transforming a boundary-value problem of electrodynamics in a domain with an uneven boundary to an equivalent problem in a domain with a boundary of a new form. The resulting problem is reduced to an integral boundary equation. This equation is solved by expansion into a series in powers of a small parameter, which is determined by the height of the irregularities in the case of a rough boundary. Impedance corrections for roughness-both determinate and randomare found for an underlying surface of arbitrary form in an inhomogeneous medium.Kharkov State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 36, No. 3-–, pp. 240–257, March–April, 1993.     

Boundary conditions for an electromagnetic field in the presence of a rough interface

Kharkov State University. Translated from Izvestiya Vysshikh Uchebykh Zavedenii, Radiofizika, Vol. 32, No. 9, pp. 1091–1096, September, 1989.