European University at Kiev

Kiev, Ukraine

European University at Kiev

Kiev, Ukraine
SEARCH FILTERS
Time filter
Source Type

Trokhimchuck P.P.,European University at Kiev
Proceedings of the International Conference on Advanced Optoelectronics and Lasers, CAOL | Year: 2016

The problem of modeling of mixed processes of Relaxed Optics (RO) is discussed. Correlations between photoinized, plasmic and thermal processes and radiated and unradiated relaxation are analyzed for various regimes of irradiation. The problem of creation stable structures is discussed too. © 2016 IEEE.


Sachuk Y.V.,European University at Kiev | Maksymuk O.V.,NASU Pidstryhach Institute for Applied Problems in Mechanics and Mathematics
Journal of Mathematical Sciences (United States) | Year: 2017

We consider contact problems of determination of the stress-strain state in the elastic half plane under the action of punches of different shapes (parabolic, cylindrical, elliptic, and hyperbolic). We study specific features of the distribution of contact pressure and stresses in the elastic half plane by using the developed software modules with the use of specially embedded libraries for the evaluation of elliptic integrals of the third kind and the construction of 3D -images and level lines. © 2016, Springer Science+Business Media New York.


Background: Human functional capabilities largely depend upon genetic qualities of person's nervous system. The registration of the spontaneous electroencephalogram (EEG) is among the physiological techniques allowing making a direct estimation of specific features of the nervous system, in particular, the human brain activity. Purpose: Research is dedicated to the study of distal muscles of the hand, in particular, its functional ability in men with a high or low background EEG α-frequency being in quiescent state or while performing usual manual movements in response to sensory signals. Methods: A test group consisting of 104 healthy men from the ages of 19 to 21 was divided into two groups according to the magnitude of their individual α- frequency (IAF) median - groups with high (n = 53, IA≥10,04 Hz) and low (n = 51, IAF≤10,03 Hz) levels of IAF. Subjects' psychodynamic properties of their nervous processes have been evaluated as well as any background and level of changes in the average amplitude of EMG while performing usual manual movements in response to sensory signals and intergroup differences were studied. Results: It has been found that higher levels of speed and accuracy of the sensorimotor response in men with a high IAF are associated with increased lateral and reciprocal significant differences both in the background muscle activity and efficiency of the distal arm muscles primarily functioning as flexors. But on the contrary, the inverse dynamics appears in men having the low-frequency which is correlated with a lower mobility and balanced nervous processes in their sensorimotor response. Conclusion: The establishment of such common factors in the experiments groups is an important step towards defining prognostic criteria for the functionality of motor area based on EMG activity of the distal muscles of the hand.


We examined 105 19- to 21-year-old men with a high or low individual modal alpha-frequency in their background EEGs. Latencies of the sensorimotor simple and complex (choice) reactions, rate capabilities of the nervous processes in the tapping test, and spectral power and coherence of the frequency EEG components were estimated. Estimations were obtained for each examined person in the resting state and during finger movements with a force loading (bending of the fingers in the fist and their spreading). Men with relatively high background modal frequencies of the alpha rhythm were characterized by a higher level of the attention selectivity and more local modifications of EEG activity related to realization of manual movements. Somewhat less-differentiated patterns of cortical activation were typical of persons with lower modal alpha-frequencies; this may correlate with a lower plasticity of the cerebral processes under conditions of the control of manual motor activity with force loading and maintenance of the pre-set movement rate. Men with higher modal alpha-frequencies demonstrated better rate indices in the performance of sensorimotor reactions. © 2017 Springer Science+Business Media, LLC


Morenko A.,European University at Kiev
Annals of Neurosciences | Year: 2014

Background: Human functional capabilities largely depend upon genetic qualities of person’s nervous system. The registration of the spontaneous electroencephalogram (EEG) is among the physiological technigues allowing making a direct estimation of specific features of the nervous system, in particular, the human brain activity. Purpose: The study is devoted to the investigation of brain processes in men with high and low levels of individual α-frequency determined in a quiescent state during the perception of sensory signals. Methods: A test group consisting of 104 right-hand healthy men from the ages of 19 to 21 was divided into two groups according to the magnitude of their individual α- frequency (IAF) median - groups with high (n = 53, IA ≥ 10,04 Hz) and low (n = 51, IAF≤10,03 Hz) levels of IAF. The power and coherence of the electrical activity of the cerebral cortex as well as inter group differences were evaluated in a quiescent state and during the perception of sensory signals by Subjects. Results: A localized power increase of the EEG α1-waves are registered in frontal areas, β1, β2- oscillations - in the anterior cortex, γ- activity - around the scalp and its decrease is present in the posterior temporal, parietal and occipital cortex leads, especially in the α- and β- frequency spectrum during the perception of sensory signals in men with a high IAF. The generalized depression of the θ-, α- and β- activity of the cortex is fixed in individuals with a low IAF while the expression of γ- waves is more local. The generalized increase of data in EEG coherence fluctuations throughout the frequency spectrum of the EEG in the cortex is set in all Subjects. The dextrocerebral preponderance is observable in posterior structures of the Subjects’ right hemisphere. A localized decrease of the coherence concerning θ-, α1-, α3-, β- and γ- oscillations are traced in the frontal and anterior temporal areas of the left hemisphere. Conclusion: We are of the opinion that the establishment of such common factors in the studied groups is an important step towards the release of the clear prognostic criteria for the functionality of men in the sensory area according to the congenital features of brain function. © 2014, Indian Academy of Neurosciences. All rights reserved.


Brenych Y.,European University at Kiev
2013 12th International Conference: The Experience of Designing and Application of CAD Systems in Microelectronics, CADSM 2013 | Year: 2013

The K-Winner-Take-All (KWTA) classifier is presented in this article. Its architecture is demonstrated. The basic steps of KWTA classifier are described. Its algorithm is presented. The KWTA structure is demonstrated. Its advantages and limitations are analyzed. © 2013 Lviv Polytechnic Natl Univ.


Reshak A.H.,University of South Bohemia | Reshak A.H.,University Malaysia Perlis | Kityk I.V.,Czestochowa University of Technology | Kityk I.V.,European University at Kiev | And 3 more authors.
Journal of Physical Chemistry B | Year: 2013

The linear and nonlinear optical properties of Ag2In 2SiS6 and Ag2In2GeS6 are calculated so as to obtain further insight into the electronic properties. The influence of using different exchange correlation potentials and the effect of replacing Si by Ge on the geometry, chemical bonding, and on the optical properties are presented. There is notable increasing in the energy band gap when moving from LDA to GGA, EVGGA then to mBJ. The effect of replacing Si by Ge atom causes a geometric change, which leads to large changes in the linear as well as the nonlinear optical susceptibilities. For the linear optical properties, it causes to increase the amplitude of the left-hand hump of ε2 average(ω) as well as a small shift of the main peak to lower energies. We have evaluated ε1 average(0) and find that a smaller energy gap yields a larger ε1(0) value. From the calculated refractive indices we obtained the birefringence, which is important for second harmonic generation (SHG) and optical parametric oscillation (OPO) as it is defined by the phase-matching condition. The second-order nonlinear optical susceptibilities, namely, the SHG are investigated for χ111 (2)(ω), χ122 (2)(ω), χ133 (2)(ω), χ221 (2)(ω), and χ331 (2)(ω). We find that χ 111 (2)(ω) is the dominant component. The microscopic second order hyperpolarizability, β111, for the dominant component χ111 (2)(ω) was obtained. We should emphasize that replacing Si by Ge enhances the linear and nonlinear optical susceptibilities so that Ag2In2GeS6 shows higher values of the linear and nonlinear optical susceptibilities and β111 in comparison to Ag2In2SiS 6. © 2013 American Chemical Society.


Khyzhun O.Y.,Ukrainian Academy of Sciences | Ocheretova V.A.,Kharkiv Polytechnic Institute | Fedorchuk A.O.,Lviv National University of Veterinary Medicine and Biotechnologies | Parasyuk O.V.,European University at Kiev
Optical Materials | Year: 2014

We report on studies of the electronic structure of Ag 2CdSnS4 single crystal grown by the horizontal gradient freeze technique. For the crystal under consideration, X-ray photoelectron core-level and valence-band spectra for pristine and Ar+-ion irradiated surfaces have been measured. The present X-ray photoelectron spectroscopy (XPS) results indicate that Ag2CdSnS4 single crystal surface is very rigid with respect to Ar+ ion-irradiation. In particular, Ar+ bombardment of the single crystal surface does not induce any significant changes of values of the binding energies of core-level electrons as well as the energy distribution of electronic states within the valence-band region. The Ar+ bombardment does not change the elemental stoichiometry of the Ag2CdSnS4 surface. For the Ag2CdSnS4 compound, the X-ray emission bands representing the energy distribution of the valence Ag d, Cd d and S p states were recorded and compared on a common energy scale with the XPS valence-band spectrum. Results of such a comparison indicate that the S 3p states contribute predominantly in the upper and central portions of the valence band of the Ag2CdSnS4 single crystal. In addition, our data reveal that the Ag 4d and Cd 4d states contribute mainly in the central portion and at the bottom of the valence band, respectively. © 2014 Elsevier B.V. All rights reserved.


Fedorchuk A.O.,Lviv National University of Veterinary Medicine and Biotechnologies | Parasyuk O.V.,European University at Kiev | Kityk I.V.,European University at Kiev | Kityk I.V.,Czestochowa University of Technology
Materials Chemistry and Physics | Year: 2013

A new approach to describe anion sub-lattice for chalcogenide compounds is proposed. The approach is developed on the base of wurtzite and sphalerite structures and includes consideration of the second coordination sphere of anion atoms. A variety of discussed examples show that the second coordination surrounding may be formed both by single anion atoms and by atom pairs or more complex configurations. Considering some chalcogenide compounds, the efficiency of such approach is demonstrated for the search of some similarities between the compounds and for optimization of corresponding quantum chemical calculations. © 2013 Elsevier B.V. All rights reserved.


Kormosh Z.,European University at Kiev | Matviychuk O.,European University at Kiev
Chinese Chemical Letters | Year: 2013

The characteristics, performance and application of membrane sensors based on ion-pair Brilliant Green mefenamate are described. The sensor's response to the mefenamate ion has the sensitivity of (86.0 ± 2.0) mV/pC over the range of 9 × 10-5-1 × 10-2 mol/L and the detection limit of 4.5 × 10-5 mol/L at pH 8.5-12. The sensor is easily assembled at a relatively low cost and has fast response time (5-10 s). The proposed sensor displayed good selectivity for mefenamate ion in the presence of different substances. It was used to determine mefenamic acid in pharmaceuticals. © 2013 Zholt Kormosh.

Loading European University at Kiev collaborators
Loading European University at Kiev collaborators