Determination of the largest lyapunov index for short chaotic time sequences in self-oscillating chemical reactions

A method was developed for the determination of largest Lyapunov index for short chaotic time sequences with allowance for the presence of noise in the response of the system. For this purpose a simple unidimensional representation modelling the dynamics of irregular self-oscillations was investigated. Conditions were found for adequate determination of the largest Lyapunov index from the noise-distorted signals. The results were used to obtain the largest Lyapunov index for the Belousov—Zhabotinskii reaction taking place in an ideal-mixing closed reactor and in a constant-mixing flow-type reactor. Institute of Organic Chemistry, National Academy of Sciences of Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 3, pp. 136–142, May–June, 1997.     

Influence of the domain structure on the permeability of planar hexaferrites in the natural ferrimagnetic resonance region

A calculation is presented of the permeability of hexaferrites with an easy magnetization plane in the region of natural ferrimagnetic resonance and in the presence of a domain structure. It is shown that the domain structure strongly influences both the magnitude of the permeability and the natural ferrimagnetic resonance frequency. The expressions obtained are compared with the results of calculations of the natural ferrimagnetic resonance spectra of single-domain planar hexaferrites. State University, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 53–57, February, 1997.     

Interaction of soliton-like light beamsin second-order non-linear materials

We investigate numerically the interaction between two light beams, initially monochromatic, during the excitation of solitary waves in quadratically non-linear media. We show that the result of the interaction is strongly dependent on soliton oscillations occurring during excitation, generating a new class of threshold phenomena.     

A method for wave decomposition in computations for nonlinear dynamical three-dimensional towing systems

We propose a new method for computing multimode wave interactions in towing systems; our method is based on wave splitting of the equations of a model in such a way that each computational step requires computation for only one mode. The efficiency of the method is demonstrated by analysis of a concrete towing system with a turning towboat. Translated fromDinamicheskic Sistermy. Vol. 12, pp. 55–64, 1993.     

Approximation of solutions of operator-differential equations by operator polynomials

We prove theorems that characterize the classes of functions whose best approximations by algebraic polynomials tend to zero with given order. We construct approximations of solutions of operator-differential equations by polynomials in the inverse operator. Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 50, No. 11, pp. 1506–1516, November, 1998.     

Criteria for controllability and observability in complex domain models of stationary systems

We propose criteria for controllability and observability of stationary systems specified by complex domain models. Conclusions concerning controllability and observability are made on the basis of coefficients in the corresponding transfer functions. Translated fromDinamicheskie Sistemy, Vol. 12, pp. 120–126, 1993.     

Asymptotic behavior of neutron small-angle multiple scattering spectra

The asymptotic behavior of the spectra for large values of the scattering vector for the case of elastic multiple small-angle neutron scattering (SANS) is investigated theoretically and experimentally. An expansion of the spectrum in terms of the reciprocal of the magnitude of the momentum transfer is obtained taking account of the influence of the instrumental line. It is shown that, to within some factor, the leading term of the expansion is identical to the differential single-scattering cross section averaged over a statistical ensemble of particles; several subsequent terms in the expansion are calculated and the range of applicability of the resulting expressions is determined. The asymptotic behavior of the multiple SANS spectrum is measured, using a two-crystal neutron spectrometer, for samples of an HTSC ceramic, the alloy Fe-Ni, and Al powder. The agreement between the experimental results and the theoretical predictions is analyzed. Zh. éksp. Teor. Fiz. 114, 2194–2203 (December 1998)     

Influence of composition and annealing on the criteria of superparamagnetism and the interaction of particles in granular electrolytically deposited films of CuCo

Films of nonuniform Cu_100−xCo_x alloys with x = 6, 11, 20, and 35 at. %, obtained by electrolytic deposition, are investigated using quantum magnetometry in fields of up to 5.5 T and temperatures of 2–300 K. In all the compositions a characteristic feature is the deviation from pure superparamagnetic behavior, which increases as the annealing of the films and their cobalt content increase. Institute of Solid State and Semiconductor Physics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 60–62, March, 1998.     

Effect of hydrogen on the current-voltage characteristics of tunneling mis diodes based on gallium arsenide

Results are presented for experimental studies of the static current-voltage characteristics of tunneling MIS diodes based on n-type gallium arsenide. It is shown that the forward branch of the current-voltage characteristics can be used to determine the dependence of the surface potential at the dielectric-semiconductor interface on the voltage and the distribution of the surface state density over energy in the forbidden band. The results of studies of these dependences for diodes prepared by thermal annealing at various temperatures are given. The possible causes of changes in the forward and reverse current, and the dependence of the surface potential on the voltage and distribution of surface state density in energy under the action on the diodes of a gaseous mixture containing hydrogen are analyzed. V. D. Kuznetsov Siberian Physicotechnical Institute at Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 69–83, January, 1998.