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Fedoryshyn O.,National Academy of Ukraine
ECCM 2012 - Composites at Venice, Proceedings of the 15th European Conference on Composite Materials | Year: 2012

The paper considers the stochastically inhomogeneous thermoelastic medium in which each component has of its elastic and thermal parameters and is described by Duhamel-Neumann law. The task of the study is to find a system of equations for the averaged strain and temperature and also to evaluate the effect of fluctuations of the thermoelastic field on the behavior of the medium. The averaged equations of thermo elasticity and thermal balance are constructed in the correlation approximation, i.e. when the physical characteristics of the phases differ little. It is shown that in Duhamel-Neuman law appears the term, dependent on time. An isothermal and adiabatic effective elastic moduli and the relaxation time are defined and also is represented method of evaluation of the stress fluctuations in stochastically inhomogeneous thermoelastic media.

Yakimenko A.I.,Taras Shevchenko National University | Bidasyuk Y.M.,National Academy of Ukraine | Prikhodko O.O.,Taras Shevchenko National University | Vilchinskii S.I.,Taras Shevchenko National University | And 2 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

We study generation and stabilization of vortex rings in atomic Bose-Einstein condensates. We suggest an approach for generating vortex rings by optical tweezers - two blue-detuned optical beams forming a toroidal void in a magnetically or optically confined condensate cloud. We demonstrate that matter-wave vortex rings trapped within the void are energetically and dynamically stable. Our theoretical findings suggest a possibility for the generation, stabilization, and nondestructive manipulation of quantized vortex rings in experimentally feasible trapping configurations. © 2013 American Physical Society.

Herasymchuk O.M.,National Academy of Ukraine
International Journal of Fatigue | Year: 2011

The purpose of this paper is to develop a generalized model for the calculation of the fatigue limit of the material based on the data on its microstructure. Relying on the experimental results of fatigue and cyclic fracture toughness tests and the analysis of the microstructure of two-phase titanium VT3-1 alloy with different structural states obtained by varying the thermo-mechanical treatment (TMT), it is shown that the dependence of the fatigue limit σ-1 on the size of the microstructural element, which is responsible for the material fatigue strength, is of a nonlinear character. The formula is derived to calculate the fatigue limit from the data on the microstructure parameters and from the results of static tensile tests of the material, which shows a very good agreement between the calculated and experimental results. The calculation results of the fatigue limit σ-1 are presented for other titanium alloys of three types, namely, pseudo-alpha alloy IMI 834, alpha + beta alloys (VT6, Ti-6-4, VT16) and beta LCB alloy, as well as for the materials with another type of the crystal lattice, such as steel 0.16%C with a body-centered cubic lattice (bcc) and brass 70%Cu/30%Zn with a face-centered cubic lattice (fcc) which justify the validity of the obtained formula. An effort has been made to explain the physical meaning of the obtained dependence. © 2010 Elsevier Ltd. All rights reserved.

Skoracki M.,Adam Mickiewicz University | Zabludovskaya S.A.,National Academy of Ukraine | Bochkov A.V.,Russian Academy of Sciences
Acarina | Year: 2012

Prostigmatan mites (Acariformes: Prostigmata) permanently parasitizing birds are reviewed at the familial level. Keys to all genera and lists of included species along with verified host records are provided. This ecological group includes about 500 species in 5 families: Cheyletidae (Cheletosomatini, Ornithocheyletiini, and Metacheyletiini), Syringophilidae, Harpirhynchidae (Harpirhynchinae and Harpypalpinae), Cloacaridae (Pneumophaginae), and Ereynetidae (Speleognathinae). The original and reference data on the external morphology, phylogeny, systematics and the host-parasite relationships of these mites are summarized. © Acarina 2012.

Anyakin N.I.,Kharkiv Polytechnic Institute | Nayebi M.,Kharkiv Polytechnic Institute | Kovalenko V.S.,Kharkiv Polytechnic Institute | Kremenitskii V.V.,National Academy of Ukraine | And 3 more authors.
Surface Engineering and Applied Electrochemistry | Year: 2014

The technological process of laser milling using the Q-switched mode is studied in this work. It is shown that the results of the laser action (the roughness of the surface and its chemical composition, the thickness of the removed layer) considerably depend on the processing conditions and the thermal and physical properties of the workpiece. The quality is also influenced by the amount of the liquid phase appearing in the case of laser heating and the fracture mode. © 2014 Allerton Press, Inc.

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