Lvivska Politekhnika National University

L'viv, Ukraine

Lvivska Politekhnika National University

L'viv, Ukraine
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Vashchyshyn L.V.,Ukrainian Academy of Sciences | Nichoha V.O.,Lvivska Politekhnika National University
Materials Science | Year: 2014

We construct an artificial neural network, with the help of which and the coefficients of continuous wavelet transformation, we can automatically detect signals from transverse cracks in rails in the defectograms recorded by a flaw-detector car. In the case where the mother wavelet function of the continuous wavelet transform and a configuration of the artificial neural network are successfully chosen, we can detect signals from defects in the initial stages of their initiation, i.e., within the period of time when the signals are comparable with noise. © 2014, Springer Science+Business Media New York.


Yavors'kyi V.T.,Lvivska Politekhnika National University | Helesh A.B.,Lvivska Politekhnika National University
Materials Science | Year: 2016

We consider the conditions of heat and mass exchange for drops of sulfuric acid in a gas flow and develop a mathematical model that enables us to determine the main parameters of evaporation of the dispersed solutions of sulfuric acid under the conditions of their direct contact with hot gases. © 2016 Springer Science+Business Media New York


Mel'nyk I.V.,Lvivska Politekhnika National University
Materials Science | Year: 2015

To establish the mean stiffnesses of reinforced-concrete beams with effective tubular inserts in bending, we used the finite-element method and the theory of shells. According to the results of theoretical analysis, it is shown that the cylindrical stiffnesses of reinforced-concrete floors with tubular inserts are different in mutually perpendicular directions. Based on the results of numerical simulations, we obtain the comparable values of cylindrical stiffnesses for monolithic reinforced-concrete floors of identical mass with tubular inserts of square, rectangular, and circular shapes. © 2015 Springer Science+Business Media New York


Havrysh V.I.,Lvivska Politekhnika National University | Kosach A.I.,Lvivska Politekhnika National University
Materials Science | Year: 2012

By using distributions, we deduce the heat-conduction equation with discontinuous and singular coefficients for an isotropic piecewise homogeneous layer containing a foreign cylindrical inclusion with heat release. With help of a piecewise linear approximation of temperature on the boundary surfaces of the inclusion and the Hankel integral transformation, we construct the numerical-analytic solution of the boundary-value problem of heat conduction with heat transfer. We also perform the numerical analysis for the case of a three-element layer containing an inclusion in the middle element. © 2012 Springer Science+Business Media, Inc.


Musii R.S.,Lvivska Politekhnika National University
Materials Science | Year: 2013

We formulate a dynamic centrally symmetric problem of thermomechanics for a hollow conducting sphere subjected to a homogeneous nonstationary electromagnetic action in the decaying sinusoid mode. We obtain the solution of this problem by using the cubic approximations of the azimuthal component of the vector of magnetic field and the radial component of the stress tensor in the radial coordinate. We also perform the numerical analysis of the thermal stressed state and the load-carrying capacity of nonferromagnetic spheres under the indicated conditions. © 2013 Springer Science+Business Media New York.


Suberlyak .V.,Lvivska Politekhnika National University | Mel'nyk Y.Y.,Lvivska Politekhnika National University | Skorokhoda V.I.,Lvivska Politekhnika National University
Materials Science | Year: 2015

We study the regularities of preparation of highly hydrophilic membranes based on the compositions of hydroxyalkyl (meth)acrylate with polyvinylpyrolidone. The relationship is established between the parameters of complex formation for a monomer and polyvinylpyrolidone in the initial composition and the composition of the polymeric network and its structural parameters. We discover efficient methods for the directed structure formation and control over the properties of the investigated membranes. © 2015 Springer Science+Business Media New York


We formulate dynamic plane axisymmetric problems of thermomechanics for long conducting hollow and solid cylinders subjected to a homogeneous nonstationary electromagnetic action. By using the cubic approximation of the axial component of the vector of magnetic-field strength and the radial component of the vector of displacements with respect to the radial coordinate, we obtain the solutions of these problems and perform the numerical investigation of the thermal stressed state and load-bearing ability of the analyzed nonferromagnetic cylinders under the electromagnetic action in the mode with pulsed modulating signal. © 2015 Springer Science+Business Media New York


Zelenyak V.M.,Lvivska Politekhnika National University
Materials Science | Year: 2014

We present a brief survey of investigations dealing with the application the method of singular integral equations to the solution of two-dimensional problems of the mechanics of bodies with cracks. Special attention is given to the steady-state problems of heat conduction and thermoelasticity for piecewise homogeneous bodies with cracks. © 2014, Springer Science+Business Media New York.


Balaban O.V.,Lvivska Politekhnika National University | Hryhorchak I.I.,Lvivska Politekhnika National University | Kondyr A.I.,Lvivska Politekhnika National University
Materials Science | Year: 2014

We study the influence of the ultrasonic treatment of pyrophyllite in different media on its structure and charge transfer and analyze the dependences of changes in the Gibbs free energy, resistance to charge transfer, and capacitance of the Helmholtz layer caused by the acoustic action on the amount of “guest” lithium x. It is shown that abnormally high diffusion coefficients of lithium cations for all investigated values of x represent a specific feature of the kinetics of intercalation in LixAL2(OH)2[Si2O5]2. © 2014, Springer Science+Business Media New York.


Havrysh V..,Lvivska Politekhnika National University
Materials Science | Year: 2015

We consider a nonlinear boundary-value problem of heat conduction for an isotropic infinite heat-sensitive layered plate with heat-insulated faces containing a foreign through thermally active inclusion. By using the proposed transformation, we perform partial linearization of the initial heat-conduction equation. As a result of a piecewise-linear approximation of temperatures on the boundary surfaces of the foreign layers and the inclusion, the equation is completely linearized. We find an analytic-numerical solution of this equation with boundary conditions of the second kind in order to determine the introduced function with the use of the Fourier integral transformation. The computational formulas for the unknown values of temperature are presented in the case of a linear temperature dependence of the heat-conduction coefficients of structural materials for the two-layer plates. The numerical analysis is performed for a single-layer plate containing a through thermally active inclusion (the material of the plate is VK94-I ceramic and the material of the inclusion is silver). © 2015, Springer Science+Business Media New York.

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