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Ufa, Russia

Ufa State Aviation Technical University ) is a state higher school, located in Ufa, Bashkortostan, Russia. Ufa State Aviation Technical University was founded in 1932 in Rybinsk, USSR. Nowadays, Ufa State Aviation Technical University has become the one of leading higher educational institutions of Russia and represents a large scientific and educational complex. There are 18 areas of study and 40 programs in its 7 faculties .More than 20,000 students study at the university. Wikipedia.

Valiev R.Z.,Ufa State Aviation Technical University
Materials Transactions | Year: 2014

Recent studies demonstrated that the processing of metallic alloys by severe plastic deformation (SPD) can result in not only strong grain refinement but also leads to the formation of grain boundaries (GBs) with different structures, including GB segregations and precipitations. These nanostructural features of SPD-processed alloys produce considerable influence on their mechanical properties. The paper presents experimental data demonstrating a superstrength and positive slope of the HallPetch relation when passing from micro- to nanostructured state in a number of metallic materials subjected to severe plastic deformation. The nature of the superior strength is associated with new strengthening mechanisms and the difficulty of generation of dislocations from grain boundaries with segregations. This new approach is used for achieving the enhanced strength in several commercial Al and Ti alloys as well as steels subjected to SPD processing. © 2013 The Japan Institute of Metals and Materials. Source

Lukashchuk S.Y.,Ufa State Aviation Technical University
Nonlinear Dynamics | Year: 2015

A new technique for constructing conservation laws for fractional differential equations not having a Lagrangian is proposed. The technique is based on the methods of Lie group analysis and employs the concept of nonlinear self-adjointness which is enhanced to the certain class of fractional evolution equations. The proposed approach is demonstrated on subdiffusion and diffusion-wave equations with the Riemann–Liouville and Caputo time-fractional derivatives. It is shown that these equations are nonlinearly self-adjoint, and therefore, desired conservation laws can be calculated using the appropriate formal Lagrangians. The explicit forms of fractional generalizations of the Noether operators are also proposed for the equations with the Riemann–Liouville and Caputo time-fractional derivatives of order (Formula presented). Using these operators and formal Lagrangians, new conservation laws are constructed for the linear and nonlinear time-fractional subdiffusion and diffusion-wave equations by their Lie point symmetries. © 2015, Springer Science+Business Media Dordrecht. Source

Chembarisova R.G.,Ufa State Aviation Technical University
Physics of Metals and Metallography | Year: 2015

The deformation behavior of copper under conditions of high-strain-rate deformation has been investigated based on the model of elastoplastic medium with allowance for the kinetics of plastic deformation. Data have been obtained on the evolution of the dislocation subsystem, namely, on the average dislocation density, density of mobile dislocations, velocity of dislocation slip, concentration of deformation-induced vacancies, and density of twins. The coefficient of the annihilation of screw dislocations has been estimated depending on pressure and temperature. It has been shown that severe shear stresses that arise upon high-strain-rate deformation can lead to a significant increase in the concentration of vacancies. The time of the dislocation annihilation upon their nonconservative motion has been estimated. It has been shown that this time is much greater than the time of the deformation process in the samples, which makes it possible to exclude the annihilation of dislocations upon their nonconservative motion from the active mechanisms of deformation. © 2015, Pleiades Publishing, Ltd. Source

Lukashchuk S.Yu.,Ufa State Aviation Technical University
Computers and Mathematics with Applications | Year: 2011

This paper presents an extension to the time integral characteristics method for estimation of parameters in fractional subdiffusion equations containing Riemann-Liouville and Caputo fractional time derivatives. The explicit representations of the fractional diffusion coefficient and order of fractional differentiation via a Laplace transform of the concentration field are obtained. A technique of optimal Laplace parameter determination by minimization of relative errors bounds is described. The effectivity of the proposed approach is illustrated by numerical example. © 2011 Elsevier Ltd. All rights reserved. Source

Valiev R.Z.,Ufa State Aviation Technical University
Nature Materials | Year: 2013

A nanostructuring processing route that leads to submicrometer grains and nanometric oxide particles uniformly distributed within the grains' interior is used to fabricate molybdenum alloys that have both exceptional high strength and ductility at room temperature. The design of the nanostructure of bulk metals and alloys should integrate theory and modeling structure characterization, processing and synthesis methods, and experimental measurement of properties. Nanostructuring strategies should provide ample opportunities to leverage multiple transport mechanisms and improve the properties of these materials, as they deal with a large number of structural parameters, such as lattice defects in the grain interior, grain-boundary structure, and the presence of segregations and second-phase nanoparticles. Nanostructuring by severe plastic deformation allows considerable enhancements in the mechanical properties. Source

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