The method of entropy minimax in the problem of identification of linear dynamic objects

Reducing the problem of identification to a problem of spectral analysis, we propose a recurrent procedure of calculations using the informational criterion of the entropy minimax. Its relation to the known solution of the problem by the least squares method is considered. The results of mathematical simulation are given. It is shown that the method of entropy minimax improves the quality of identification and the speed of convergence, and, as a result, minizizes requirements on the length of the analyzed sample.State Technical University, Nizhny Novgorod. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, No. 5, pp. 415–421, May, 1995.     

The theory of the spin-spin relaxation of electron subsystem in antiferromagnets and polyenes

The theory of conductivity of rare earth compounds and polyenes is constructed on the basis of the fluctuational theory of magnetic superconductors. The criterion of the appearance of the high-temperature superconducting phase in rare earth antiferromagnetic compounds and of the superconductivity in polyene systems is found.     

Exoelectron emission from solid nitrogen

Solid nitrogen was investigated by activation spectroscopy methods – thermally stimulated luminescence and thermally stimulated exoelectron emission (TSL and TSEE) in combination with luminescence analysis. TSEE from solid nitrogen pre-irradiated by an electron beam was measured and investigated for the first time. A set of peaks both in TSL and TSEE were observed. It was found that one of the peaks in the TSEE curve is caused by release of electrons in the course of the α-β phase transition of solid nitrogen. The corresponding activation energy was estimated.     

Antiferromagnet with an antisymmetry center in an external static magnetic field as a left-handed medium

Using the example of a tetragonal easy-axis antiferromagnet with a 4 _z ⁻2 _x ⁺ I ⁻ structure, the conditions have been determined under which both the negative refraction effect and the negative phase velocity effect are simultaneously possible in an external field orthogonal to the easy axis. The results are extended to multiferroics with the uniform magnetoelectric effect and to centrosymmetric magnets.     

Low-density carbon material modified with pyrolytic carbon

Here we report a physicochemical investigation of low-density carbon materials modified with pyrolytic carbon (PC). Exfoliated graphite (EG) obtained by nitrate expandable graphite thermal destruction was pressed into low-density graphite materials (LDGMs) with densities of 0.045-0.50 g/cm³ and saturated with PC by impact CVI technique. LDGM infiltration with PC leads to sample weight and density growth. The amount of deposited PC strictly depends on synthesis conditions. The maximum surface and volume deposition of PC occurred for samples with density of 0.05 g/cm³. XRD, Raman spectroscopy and scanning electron microscopy revealed that the deposited PC is of smooth laminar (SL) type. Composite thermal conductivity is about 2-3.5 Wt/m K.     

A New Non-Overlapping Domain Decomposition Method for a 3D Laplace Exterior Problem

We propose a method for solving three-dimensional boundary value problems for Laplace’s equation in an unbounded domain. It is based on non-overlapping decomposition of the exterior domain into two subdomains so that the initial problem is reduced to two subproblems, namely, exterior and interior boundary value problems on a sphere. To solve the exterior boundary value problem, we propose a singularity isolation method. To match the solutions on the interface between the subdomains (the sphere), we introduce a special operator equation approximated by a system of linear algebraic equations. This system is solved by iterative methods in Krylov subspaces. The performance of the method is illustrated by solving model problems.     

Mixed-Ligand Europium(III) Complexes with 4-Methylbenzoic Acid

Russian Journal of General Chemistry - Europium(III) complexes with p-methylbenzoic acid and nitrogen- or phosphorus-containing neutral ligand with the compositions [Eu(p-MBA)3·D]2·xH2O...     

Weak localization in graphene flakes

We show that the manifestation of quantum interference in graphene is very different from that in conventional two-dimensional systems. Because of the chiral nature of charge carriers, it is not only sensitive to inelastic, phase-breaking scattering, but also to a number of elastic scattering processes. We study weak localization in different samples and at different carrier densities, including the Dirac region, and find the characteristic rates that determine it. We show how the shape and quality of graphene flakes affect the values of the elastic and inelastic rates and discuss their physical origin.