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Seregin Maxim S., Naberezhnov Alexander A., Shaganov Anton P., Sysoeva Anna A.

Temperature stability of ferroelectric phase in potassium nitrate nanoparticles

Published in category «Condensed matter physics»

Powder X-ray diffraction spectra of potassium nitrate embedded into porous boron-silicate glasses have been obtained. The temperature range of spectra recording was 100 – 400 K. The phase ratio of samples at various temperatures and its relationship to temperature treatment and to the way of embedding material were analyzed.

Views: 1950 Comments: 0

Semenov Artem S.

The identification of anisotropy parameters of phenomenological plasticity criterion for single crystals worked out on the micromechanical model basis

Published in category «Condensed matter physics»

The analysis of the predictive ability of the Hill quadratic criterion of plasticity has been carried out for monocrystalline nickel based superalloys. The possibilities of determining the parameters of the quadratic criterion on uniaxial tensile tests for single-crystal samples of different crystallographic orientation were investigated. The experimental results and predictions of micromechanical model with the Schmid criterion were compared. In order to improve the prediction accuracy the phenomenological fourth degree criterion of plasticity was proposed, that allowed taking into account a number of effects that could not be described by a quadratic criterion.

Views: 1517 Comments: 0

Alekseeva Olga A., Naberezhnov Alexander A., Poprawsky Ryszard

Pecularities of melting and crystallization of low-melting metal nanoparticles

Published in category «Condensed matter physics»

The melting and crystallization processes of low-melting metals (gallium and indium) embedded into porous glasses with average pores diameters of 2 and 7 nm have been studied by differential scanning calorimetry. The applicable Tm and Tcr temperatures and a thermal hysteresis between these processes were determined. The hysteresis values were found to increase with reducing the average pore diameter.

Views: 1494 Comments: 0

Bakaev Alexander V., Zhurkin Evgeniy E.

Characterization of radiation defects in austenitic alloys

Published in category «Condensed matter physics»

Numerical calculation of formation energy of different radiation defects at zero temperature (T = 0 K) in the austenitic Fe0.7Ni0.1Cr0.2 model alloy using classical molecular dynamics method has been carried out. Thermal stability of the radiation defects by means of annealing modeling at different non-zero temperatures was studied.

Views: 1029 Comments: 0

Bakaev Alexander V., Zhurkin Evgeniy E.

Atomic-scale simulation of dislocations in the iron austenitic alloy

Published in category «Condensed matter physics»

We have investigated the movement of dislocations in a model iron alloy with 10 % Ni and 20 % Cr by means of computer simulation in order to study an interaction of dislocations with radiation defects in metals afterwards. Among other things, we tested the model of periodical dislocations and calculated a set of dislocation characteristics.

Views: 948 Comments: 0

Igolkin S.I., Melker Alexander I.

Molecular hydrodynamics of underwater explosion

Published in category «Simulation of physical processes»

In this contribution we report on modeling underwater explosion in the framework of molecular dynamics. We have developed a computer program which allows studying the underwater explosion in two dimensional Lennard-Jones liquid. Calculations of the dynamical structure of underwater explosion displayed the striking resemblance of the underwater-explosion evolution obtained and the real process; namely, generation of a shock wave and its expanding; formation of a cavity; disintegrating the shock wave, when reaching a surface, into two parts which begin to move in the opposite direction parallel to the surface; transforming the cavity into a water crater of an arising water volcano; its activity and decay.

Views: 1442 Comments: 0

Pogoda Anastasiya P., Petrov Victor M.

The spectral selectivity of reflective holographic gratings in the BaTiO3:Co crystal

Published in category «Physical optics»

The spectral selectivity of refractive-index gratings in the BaTiO3: Co crystal has been investigated. A new technique for the spectral selectivity measurement of thick reflective holograms was suggested. That technique allowed direct measurement of the spectral selectivity of gratings using a tunable wavelength laser reader. A good agreement between experimental data and theoretical calculations was obtained.

Views: 1368 Comments: 0

Semenov Semen N., Vorobyev Stanislav I., Dudkin Valentin I.

Constructing a microwave image of an object using the inverse diffraction problem

Published in category «Physical optics»

The paper designs a calculation procedure for the electromagnetic field to construct a microwave image of an object. The procedure suggested was tested with the AMu256 experimental setup. We proved it was possible to create the construction required in real-time using this setup.

Views: 1592 Comments: 0

Miroshnikov Konstantin A., Simakova Maria N.

The structure and properties of gp181 lytic enzyme of phiKZ bacteriophage

Published in category «Biophysics and medical physics»

In this paper the gp181 peptidoglycan hydrolase (structural lysin) of phiKZ bacteriophage Pseudomonas aeruginosa has been investigated. The study of gp181 was performed using directed deletion mutagenesis. The assumption that the C-terminal part of gp181 may be involved in the infection process as the sensory molecular needle-like cell-puncturing device of phiKZ was experimentally confirmed.

Views: 1425 Comments: 0

Khokhlyuk Vitaly I.

The illustration of the calculating partitioning procedures

Published in category «Mathematics»

The present article continues a series of papers devoted to the numerical solution of practical mixed optimization problems. Previously the partitioning theorem of the indicated mixed maximization problem was formulated and proved. In this article some methods for solving problems by partitioning, including the graphical method, a three-step procedure, and the iterative procedures 1 and 2, are shown by a specific example of the solution of the simplest mixed maximization problem. A feasible set of the problem and the convex hull of this set are graphically presented within the framework of solving the problem.

Views: 1288 Comments: 0

Petrichenko Mikhail R.

Extreme properties of solutions of a parabolic equation

Published in category «Mathematics»

Rational procedures and properties of solutions of limiting problems have been considered for equations and limiting problems with partial derivatives of a parabolic type. It was proved that such limiting problems for parabolic equations admitting the group of self-transformations were necessary conditions for a minimum of positive functionals; furthermore, the Crocco equation was proved to be equivalent to a canonical system and its applicable functional was shown to be found at once. It was also demonstrated that someone was able to bring a parabolic equation in its original notation into a canonical form using additive doubling variables.

Views: 1520 Comments: 0

Kachalov Vasily I.

Holomorphic in the parameter integrals of the second-order equations perturbed singularly and limit theorems

Published in category «Mathematics»

Holomorphic in the parameter integrals of the second-order equations perturbed singularly have been built up on the basis of homomorphisms of algebras of holomorphic functions of different numbers of variables. A limit transition theorem follows from those integrals.

Views: 1286 Comments: 0

Tikhomirov Victor V.

Longitudinal shear crack terminating at a wedge-shaped elastic inclusion

Published in category «Mechanics»

The interaction between a semi-infinite crack of mode III and a wedge-shaped elastic inclusion has been considered. The stress singularity at the crack tip was investigated. It was shown that the stress asymptotics was able, unlike the classical case, to have two singular terms at some parameter values for composite material. A crack deflection by the interface was analyzed.

Views: 1421 Comments: 0

Tsygan Anatoly I., Shalybkov Dmitry A., Barsukov Dmitry P., Goglichidze Oleg A.

An analysis of differential rotation of neutron star polar caps for the case of the anisotropic conductivity of the cap substance

Published in category «Astrophysics»

The differential rotation of liquid polar caps caused by magnetospheric currents closing up under neutron star surface has been considered. The anisotropy of cap electric conductivity and viscosity due to magnetic field was taken into account. The rotation velocity was shown to be very slow and almost all electric current was brought out to close up deeper, inside the rigid crust.

Views: 1229 Comments: 0

Belyavsky Grigoriy I., Misyura Il’ya V.

Signal filtering with jumps during discrete time and under finite horizon

Published in category «Radiophysics»

The problem of filtering signals with jumps occurring at random times on a background of white noise in discrete time and with finite horizon has been considered. Two signal models being discrete analogs of diffusion with jumps were developed.

Views: 1392 Comments: 0