Nikulin I.L.,Perm National Research Polytechnic Institute
Magnetohydrodynamics | Year: 2016
Convection in molten metal exposed to an alternating magnetic field is investigated numerically. Governing equations are written in an axial symmetric laminar approximation and include equations for the calculation of magnetic fields and eddy currents; the motion equations in the Boussinesq approximation take into account averaged time independent electrodynamic forces acting in conducting liquids; the heat transfer equation employs averaged Joule heat sources. The correctness and the applicability of the laminar axisymmetric model to describe turbulent heat and mass transfer in a magnetic field was proved by verification and comparison with physical experiment. The in uence of buoyancy and alternating magnetic field generated forces on the generation of melt ows in the melt volume and at the surface is shown for different field geometries and frequencies. Results obtained in extreme cases are compared with results in the literature. The stability condition for oxide scab on the melt surface is described, the alternating magnetic field impacts on it are investigated. Ways to remove the oxide scab are suggested.
Letyagin I.Y.,Perm National Research Polytechnic Institute
Materials Science Forum | Year: 2017
The manufacturing of significant products with help of laser beam welding technologies requires higher stability characteristics of such technologies; this explains the necessity to run online testing procedures of through pro-melting process. This type of testing can be carried out by the registration of plasma streams that occur under a work piece by through pro-melting [i.e. metal undergoes an intensive laser beam thermal processing]. © 2017 Trans Tech Publications, Switzerland.
Fedoseeva E.M.,Perm National Research Polytechnic Institute
Materials Science Forum | Year: 2017
In work the analysis of influence of structurization and nonmetallic inclusions on regularity of change of growth rate of a fatigue crack in different zones of a welded seam of steel X65 is carried out. Welded seams of the pipelines received by a combined method of welding of STT+API were investigated. Growth rate of a fatigue crack low in a root of the seam received when welding in the way STT. On border of the fatigue crack passing in the filling layers of a welded seam the inclusions which are settling down chains on borders of grains are found, being concentrators of tension. © 2017 Trans Tech Publications, Switzerland.
Asnin L.,Konkuk University |
Asnin L.,Perm National Research Polytechnic Institute
Journal of Chromatography A | Year: 2012
The review delivers the analysis of the literature data on adsorption equilibrium in chiral systems. Chiral adsorbents usually comprise several groups of nonselective and enantioselective active sites. Each group may be heterogeneous in itself. A dynamic equilibrium between different conformations of chiral selectors, nonstoichiometric adsorption, and various secondary equilibria also contribute to the complexity of the phenomenon. In this context, the practice of the use and the limitations of the conventional single-site and two-site models of chiral stationary phase were considered. Special attention was given to problems of the interpretation of experimental results and rational approaches to the selection of physically meaningful adsorption models. The effect of chirality on mass transfer kinetics was also considered, although available information is limited and sometimes ambiguous in order to make solid conclusions. © 2012 Elsevier B.V.
Plunian F.,Joseph Fourier University |
Stepanov R.,Perm National Research Polytechnic Institute |
Frick P.,Perm National Research Polytechnic Institute
Physics Reports | Year: 2013
Shell models of hydrodynamic turbulence originated in the seventies. Their main aim was to describe the statistics of homogeneous and isotropic turbulence in spectral space, using a simple set of ordinary differential equations. In the eighties, shell models of magnetohydrodynamic (MHD) turbulence emerged based on the same principles as their hydrodynamic counter-part but also incorporating interactions between magnetic and velocity fields. In recent years, significant improvements have been made such as the inclusion of non-local interactions and appropriate definitions for helicities. Though shell models cannot account for the spatial complexity of MHD turbulence, their dynamics are not over simplified and do reflect those of real MHD turbulence including intermittency or chaotic reversals of large-scale modes. Furthermore, these models use realistic values for dimensionless parameters (high kinetic and magnetic Reynolds numbers, low or high magnetic Prandtl number) allowing extended inertial range and accurate dissipation rate. Using modern computers it is difficult to attain an inertial range of three decades with direct numerical simulations, whereas eight are possible using shell models.In this review we set up a general mathematical framework allowing the description of any MHD shell model. The variety of the latter, with their advantages and weaknesses, is introduced. Finally we consider a number of applications, dealing with free-decaying MHD turbulence, dynamo action, Alfvén waves and the Hall effect. © 2012 Elsevier B.V.
Tashkinov M.,Perm National Research Polytechnic Institute
Computational Materials Science | Year: 2014
The aim of this research is to develop the mechanisms of calculation of stress and strain fields' statistical characteristics in components of heterogeneous solid media in dependence on variation of internal and external parameters in elastoplastic case. Analytical expressions for statistical characteristics of structural fields, such as mean values and dispersions, are formed using solution of stochastic boundary value problems and structural multipoint correlation functions. The boundary value problems have been solved in elastoplastic case in the second approximation with the Green's functions method. The multipoint correlation functions up to fifth order have been built for synthesized 3D material microstructure RVE models with polydisperse spherical inclusions. New analytical expressions and numerical results for statistical characteristics in components of elastoplastic heterogeneous solids with different types of structural parameters and properties of the phases have been obtained for simple shear state of strain. Numerical results are presented for porous composites with different inclusions volume fraction in case of simple shear state of strain. © 2014 Elsevier Ltd. All rights reserved.
Kameneva A.L.,Perm National Research Polytechnic Institute
Research Journal of Pharmaceutical, Biological and Chemical Sciences | Year: 2014
The temperature conditions for different formation stages of nanostructured and polycrystal Ti1-xAlxN thin films have been identified for the first time, using cathodic arc evaporation. A three-axis structural zone model has been developed to identify structural zones of Ti1-xAlxN thin films. This model, combined with chemical analysis, has been used to establish a pattern for 0 ≤ x ≤ 0.4 in Ti1-xAlxNthin films with reference to the formation process and temperature conditions. Nanostructured Ti0,6Al0,4N films formed at the maximum film heating rate and at the optimum gas mixture pressure have the highest aluminum content CAl=x= 28.7 at.% and the film composition approaches the stoichiometric one. If the CAl is higher than 26.5 at.% and the CAl/CTi=x/1-x is higher than 0.6, the size of the coherent scattering region (CSR) declines sharply to 10 nm. The degree of texturization of the Ti1-xAlxN thin films steadily increases with the growth of the XAl and CAl/CTi. An improvement in physical and mechanical properties of Ti1-xAlxN thin films can be achieved by bringing the CAl to > 26.5 at.%, by bringing the CAl/CTi to > 0.6, by reducing the CSR size to 10 nm, by ordering the microstructure, and by increasing the degree of texturization of Ti1-xAlxN thin films to 0.8. The Ti1-xAlxN thin films also exhibit excellent sliding wear resistance and a low friction coefficient due to maximum full free energy of 71.3 eV and Al2O3 layer which diminishes O2 diffusion into Ti1-xAlxN thin film and preserves its microhardness at high temperatures. If the CAl and CAl/CTi conditions are not met, the influence of Ti1-xAlxN films on the properties is significant.
Kameneva A.L.,Perm National Research Polytechnic Institute
Research Journal of Pharmaceutical, Biological and Chemical Sciences | Year: 2015
The influence of the sequence and deposition method of TiN, ZrN and Tix Zr1-xN layers of multi-layer coatings with respect to the corrosion resistance of hard alloy in sodium hydroxide solution has been studied by electrochemical methods (polarization and impedance measurements) and optical microscopy. It is shown that various corrosion resistance of multi-layer coatings is caused by surface defects and internal defects of the coating layers as well as differences in the oxygen adsorption on the coatings surface in 5% solution of NaOH (without de-aerating) and, consequently, differences in the adsorption of intermediates and differences in the rate constants of charge transfer.
Serebrennikov A.M.,Perm National Research Polytechnic Institute
Plasmonics | Year: 2013
In this work, the theoretical model explaining the frequency scaling and multi photon effects in metal nanoparticles has been suggested. Its capabilities are demonstrated in relation to the second and third harmonic generation phenomena and the four-wave mixing phenomena as well. The continuum mechanical description of the electron gas of valence electrons underlies the theory. The principal equations of motion are deduced by the Hamilton's least action principle. The compatibility of the model with the Drude theory is demonstrated in the linear case. On the basis of the proposed model, we investigate the effect of Coulomb interaction in clusters of metal nanoparticles and the resulting motion of particles under the assumption of the compliance of an ambient medium. © 2013 Springer Science+Business Media New York.
Trushnikov D.,Perm National Research Polytechnic Institute
Sensors (Basel, Switzerland) | Year: 2012
Electron beam welding (EBW) shows certain problems with the control of focus regime. The electron beam focus can be controlled in electron-beam welding based on the parameters of a secondary signal. In this case, the parameters like secondary emissions and focus coil current have extreme relationships. There are two values of focus coil current which provide equal value signal parameters. Therefore, adaptive systems of electron beam focus control use low-frequency scanning of focus, which substantially limits the operation speed of these systems and has a negative effect on weld joint quality. The purpose of this study is to develop a method for operational control of the electron beam focus during welding in the deep penetration mode. The method uses the plasma charge current signal as an additional informational parameter. This parameter allows identification of the electron beam focus regime in electron-beam welding without application of additional low-frequency scanning of focus. It can be used for working out operational electron beam control methods focusing exactly on the welding. In addition, use of this parameter allows one to observe the shape of the keyhole during the welding process.