Time filter

Source Type

Zinko R.,National Transport University
Vibrations in Physical Systems | Year: 2014

The use of graphs for the research of a rotor crush machine work on elastic foundation is offered. For machines the structure graph of its design is being written. The graph of levels structure of the generalized coordinates of mathematical model is being formed on the basis of structure graph of machine design. It allows building of the mathematical model, which describe the physical processes of the machine work quickly and qualitatively. © by Poznan University of Technology, Poznan, Poland 2014.

Grigorenko A.Y.,Ukrainian Academy of Sciences | Loza I.A.,National Transport University
International Applied Mechanics | Year: 2013

The propagation of nonaxisymmetric waves in layered hollow cylinders with radially polarized piezoceramic layers is studied. The associated problem is solved with an effective numerical-analytic method. The original three-dimensional problem of electroelasticity for partial differential equations is reduced to a boundary-value eigenvalue problem for ordinary differential equations by representing the components of the stiffness tensor, displacement vectors, electric-flux density, and electrostatic potential as standing circumferential waves and traveling axial waves. The problem is solved with the stable discrete-orthogonalization method in combination with the incremental search method. The dispersion equations are numerically analyzed over a wide range of variation in the geometrical characteristics of cylinders with piezoceramic layers © 2013 Springer Science+Business Media New York.

Vakulenko I.O.,National Transport University
Materials Science | Year: 2016

It is shown that the intense cooling (with rates of 2–9°C/sec) of wheel rims after their hot rolling in a rolling mill increases the yield limit and the ultimate strength of the metal. It is also established that, in the absence of supersaturation of the solid solution with carbon atoms in the course of this kind of cooling, the mechanical properties of carbon steel are determined solely by the internal stresses caused by the phase hardening of ferrite in pearlite and the state of ferrite–cementite boundaries. © 2016 Springer Science+Business Media New York

Gulyayev V.I.,National Transport University | Shevchuk L.V.,National Transport University
Journal of Vibration and Acoustics, Transactions of the ASME | Year: 2016

The problem about computer simulation of whirl vibrations of a drill bit is considered. The dynamic process is assumed to be in an incipient stage when the bit rolls on the borehole bottom without reaching the well wall. Mathematic models of the bit moving based on assumptions of frictional (rolling with sliding) and kinematic (pure rolling) contact between the bit and borehole bottom surfaces are elaborated. The influence of the drill string (DS) bending flexibility and the bit shape on the whirl process is discussed. The most typical whirl phenomena are grounded due to computer simulation. © 2016 by ASME.

Khoroshev K.G.,National Transport University
International Applied Mechanics | Year: 2010

Generalized complex potentials, their expressions for a domain with elliptic holes, and the discrete least-squares method are used to analyze the generalized plane electroelastic state of a piezoelectric plate having holes and cracks with electric potentials applied to their boundaries. There are no mechanical loads. A numerical analysis is conducted. The effect of the applied voltage on the electroelastic state of the plate is examined © 2010 Springer Science+Business Media, Inc.

Gladush V.D.,Dnipropetrovsk National University | Galadgyi M.V.,National Transport University
General Relativity and Gravitation | Year: 2011

We propose the method of investigation of radial motions for charged and neutral test particles in the Reissner-Nordström field by means of mass potential. In this context we analyze special features of interaction of charges and their motions in General Relativity and construct the radial motion classification. For test particles and a central source with charges q and Q, respectively, the conditions of attraction (when qQ > 0) and repulsion (when qQ < 0) are obtained. The conditions of motionless test particle states with respect to the central source are investigated and, in addition, stability conditions for such static equilibrium states are found. It is shown that stable states are possible only for the bound states of weakly charged particles in the field of a naked singularity. Frequencies of small oscillations of test particles near their equilibrium positions are also found. © 2011 Springer Science+Business Media, LLC.

Gulyayev V.I.,National Transport University | Hudoly S.N.,National Transport University | Glovach L.V.,National Transport University
International Journal of Solids and Structures | Year: 2011

The problem about identification of resistance forces acting on a drill column moving in an inclined bore-hole is stated. It is supposed that the well trajectories can have geometrical imperfections in the shape of cylindrical spiral or plane cosinusoidal curves. The system of ordinary differential equations is derived on the basis of the theory of curvilinear flexible elastic rods. It permits one to describe static effects of the drill column bending accompanying the processes of its raising, lowering and rotating inside the bore-hole. Through the use of this system the direct and inverse problems of the drill column deforming are formulated for calculation of internal and external resistance forces acting on the drill column tube. The methods for numerical solution of the constructed equations are elaborated. With their use the phenomena of the drill columns motion and their frictional seizure inside the bore-holes are simulated for different geometrical imperfections and relations between the velocities and directions of their rotation and axial motion. © 2010 Elsevier Ltd. All rights reserved.

Gulyayev V.I.,National Transport University | Borshch O.I.,National Transport University
Journal of Petroleum Science and Engineering | Year: 2011

This paper considers the problems on investigation of the dynamic bending of elongated drill string tubes studied with allowance made for destabilizing effects of the longitudinal non-uniform preloading, action of torque, inertia forces of rotation and internal flows of washing liquid (mud). As a result of the completed analysis, natural wave and vibration modes are constructed, their frequencies are calculated. It is shown through the study of appropriate dispersion equations that free bending vibrations of unbounded rods can be realized only in the modes of regular dextral and sinistral spiral waves propagating with different velocities in different directions. The modes of free vibrations of the bounded drill strings possess more complicated irregular spiral shapes. © 2011 Elsevier B.V.

Sopotsko O.Y.,National Transport University
Actual Problems of Economics | Year: 2014

The article describes the conditions of the cycle for food products (perishable cargo) delivery and the requirements to the logistics delivery cycle for such cargos. The algorithm to solve practical problems of this logistics cycle optimization is offered. An example of this algorithm use is given along with the best routes for cargo delivery from stock to retail outlets is provided.

Borovoy N.A.,Taras Shevchenko National University | Ishchenko R.N.,National Transport University
Optics and Spectroscopy (English translation of Optika i Spektroskopiya) | Year: 2013

The relative intensities of the M 5 N and M 4 N satellites of Pb under electron bombardment of thick targets in the range of accelerating voltages U = 5-30 kV are experimentally investigated. Based on the previously proposed model of M X-ray emission, the relative intensities of these satellites are calculated using the total ionization cross sections of M subshells under electron impact found in different approximations. It is established that, among the models yielding analytical expressions for calculating total ionization cross sections, the model of classical binary collisions provides the best agreement with experimental data in the electron energy range under study. The parameters of the semiempirical Bethe formula for calculating the ionization cross sections of Pb M subshells under electron impact are determined. © 2013 Pleiades Publishing, Ltd.

Loading National Transport University collaborators
Loading National Transport University collaborators