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Wyszukujesz frazę "Vovk, R." wg kryterium: Autor


Wyświetlanie 1-8 z 8
Tytuł:
Magnetoresistance and Intrinsic Pinning of Vortices in the Untwinned $YBa_2Cu_3O_{7 - δ}$ Single Crystals with Optimal Oxygen Content and a Small Deviation from the Oxygen Stoichiometry
Autorzy:
Vovk, R.
Gvozdikov, V.
Obolenskii, M.
Nazyrov, Z.
Kruglyak, V.
Powiązania:
https://bibliotekanauki.pl/articles/1427580.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Fy
74.25.Qt
Opis:
We study the temperature dependence of the in-plane magnetoresistance $ρ_{ab}(T)$ in untwinned $YBa_2Cu_3O_{7 - δ}$ single crystals with the optimal oxygen content and with a small deficit of oxygen atoms at different angles between the external magnetic field 15 kOe and the ab-planes α. We found that at high temperatures in the pseudogap region external magnetic field does not affect the $ρ_{ab}(T)$ but it broadens transitional region $T_{c} - T_{c0}$ from 0.3 K at zero field and α = 0 to approximately 6 K at α = 60° in the field. In case of optimal doping the function $ρ_{ab}(T)$ display a 3D to 2D dimensional crossover when temperature decreases from $T_{c}$ to $T_{c0}$ and scaling near the $T_{c0}$ which we relate to the flux-flow and vortex-lattice melting. In the underdoped sample the vortices are effectively pinned by the random oxygen vacancies and the function $ρ_{ab}(T)$ in transitional region has smooth tails without any traces of crossover and scaling.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1191-1194
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Oxygen Redistribution on Temperature Dependence of Pseudo-Gap in Underdoped $HoBa_{2}Cu_{3}O_{7-δ}$ Single Crystals
Autorzy:
Vovk, R.
Nazyrov, Z.
Obolenskii, M.
Pinto Simoes, V.
Januszczyk, M.
Latosińska, J.
Powiązania:
https://bibliotekanauki.pl/articles/1493662.pdf
Data publikacji:
2011-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
Opis:
The effect of annealing at room temperature on the excess conductivity of oxygen deficient $HoBa_2Cu_{3}O_{7 - δ}$ single crystal is studied. It is shown that there is substantial extension of the interval of linear dependence $ρ_{ab}$ (T) and narrowing of the temperature area of the pseudo-gap regime as a result of annealing. The excess conductivity satisfies the exponential temperature dependence in a wide temperature interval. The temperature dependence of the pseudogap is satisfactorily described by the BCS-BEC theoretical model.
Źródło:
Acta Physica Polonica A; 2011, 120, 3; 512-515
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Excess Conductivity of Y$\text{}_{0.95}$Pr$\text{}_{0.05}$Ba$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-x}$ Single Crystals
Autorzy:
Vovk, R. V.
Obolenskii, M. A.
Bondarenko, A. V.
Goulatis, I. L.
Chroneos, A.
Powiązania:
https://bibliotekanauki.pl/articles/2047236.pdf
Data publikacji:
2007-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Eh
72.10.-d
74.40.+k
74.72.-h
Opis:
In this work we investigate the conductivity in the basis plane of YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-x}$ and Y$\text{}_{1-z}$Pr$\text{}_{z}$Ba$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-x}$ single crystals with a system of one-direction twin boundaries. The Pr dopants behave as efficient scattering centers of normal and fluctuating carriers. For this a slight doping with praseodymium (till z≈0.05) results in a significant narrowing of the temperature interval in which the pseudo-gap regime is realized in the ab-plane of YBaCuO single crystals.
Źródło:
Acta Physica Polonica A; 2007, 111, 1; 129-133
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Compression Changes in Electrical Resistance and Critical Temperature of $Nb_{1-x}Se_2Sn_x$ Single Crystals
Autorzy:
Obolenskiy, M.
Zavgorodniy, A.
Vovk, R.
Nazyrov, Z.
Goulatis, I.
Januszczyk, M.
Latosińska, J.
Powiązania:
https://bibliotekanauki.pl/articles/1419810.pdf
Data publikacji:
2012-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Fy
74.62.Fj
Opis:
In this work we investigate the influence of hydrostatic pressure (up to 12 kbar) on the critical parameters of $Nb_{1-x}Se_2Sn_x$ (x=0.1 and x=0.15) single crystals. It is shown that a change in the density of states at the Fermi level brings the main contribution to the increase in $T_{c}$ under pressure. Under the effect of hydrostatic pressure, the phonon spectrum is shifted to higher frequencies (narrowed). The estimated Debye temperature is consistent with those obtained from the heat capacity measurements in $NbSe_2$ single crystals. It is shown that upon increasing hydrostatic pressure the mean free path increases and $Nb_{1-x}Se_2Sn_x$ should be considered as the pure limit in the Ginzburg-Landau theory.
Źródło:
Acta Physica Polonica A; 2012, 122, 1; 159-161
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vacancy-Fluorine Clusters in Silicon
Autorzy:
Chroneos, A.
Vovk, R.
Goulatis, I.
Nazyrov, Z.
Pinto Simoes, V.
Januszczyk, M.
Latosińska, J.
Powiązania:
https://bibliotekanauki.pl/articles/1504564.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
31.15.es
61.72.jd
61.72.uf
61.72.Yx
Opis:
Fluorine (F) doping and the formation of F-vacancy $(F_{n}V_{m})$ clusters have been extensively studied in silicon (Si) as they can suppress the transient self-interstitial mediated diffusion of boron (B). Recent experimental studies by Bernardi et al. revealed that there is no significant concentration of $F_{n}V_{m}$ clusters (for n ≥ 4, m ≥ 1) in disagreement with a number of density functional theory studies. In the present study we use electronic structure calculations to evaluate the binding energies of $F_{n}V_{m}$ clusters and $V_{n}$ clusters. The significant binding energies of the $V_{n}$ clusters reveals that the concentration of the large $F_{n}V_{m}$ clusters (n ≥4, m ≥1) will be limited compared to the $V_{n}$ clusters or even smaller clusters.
Źródło:
Acta Physica Polonica A; 2011, 119, 6; 774-777
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Scattering Processes of Normal and Fluctuating Carriers in ReBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ (Re = Y, Ho) Single Crystals with Unidirectional Twin Boundaries
Autorzy:
Vovk, R. V.
Obolenskii, M. A.
Bondarenko, A. V.
Goulatis, I. I.
Levy, M. R.
Chroneos, A.
Powiązania:
https://bibliotekanauki.pl/articles/2047234.pdf
Data publikacji:
2007-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Eh
72.10.-d
74.40.+k
74.72.-h
Opis:
The effect of twin boundaries on the normal and fluctuating conductivity of ReBaCuO (Re = Y, Ho) single crystals was investigated. The results indicate that the Lawrence-Doniach theoretical model describes adequately the temperature dependence of the excess conductivity. The twin boundaries are efficient scattering centers for normal and fluctuating carriers. The derived values of the coherence length perpendicular to the ab-planeξ$\text{}_{c}$(0) are in good agreement with those obtained from magnetic measurements for stoichiometric YBaCuO crystals.
Źródło:
Acta Physica Polonica A; 2007, 111, 1; 123-128
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Beef cattle breeding in Ukraine
Hodowla bydła mięsnego na Ukrainie
Autorzy:
Pilarczyk, R.
Vovk, S.
Kruzhel, B.
Powiązania:
https://bibliotekanauki.pl/articles/45081.pdf
Data publikacji:
2015
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Źródło:
Acta Scientiarum Polonorum. Zootechnica; 2015, 14, 2
1644-0714
Pojawia się w:
Acta Scientiarum Polonorum. Zootechnica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of internal efforts in the components of the crop sprayer boom section
Autorzy:
Hevko, R.
Stashkiv, M.
Lyashuk, О.
Vovk, Y.
Oleksyuk, V.
Tson, O.
Bortnyk, I.
Powiązania:
https://bibliotekanauki.pl/articles/1818799.pdf
Data publikacji:
2021
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:
potential energy of deformation
static indeterminacy
load-bearing structure
boom section of a crop spraying machine
simulation
energia potencjalna
energia deformacji
konstrukcja nośna
wysięgnik
maszyna do opryskiwania
symulacja
Opis:
Purpose: Development results allow the defects in the boom section of a crop spraying machine design to be found, the most loaded structural components to be determined and the most suitable design parameters to be chosen. Design/methodology/approach: Results of theoretical investigation of internal forces distribution in the components of a boom section of a crop spraying machine in the static statement of the problem have been presented. The applied under discussion enables the static indeterminacy to be realized whilst calculating the complex frame structures though it requires not only considerable records of the function of potential energy of deformation (even without taking into account the function of potential energy of deformation of normal and lateral forces) but application of applied computer programs. The technique of static indeterminacy realization by minimum of potential energy of deformation (MPED) method has been used to calculate the framework. Findings: Technique of static indeterminacy realization by minimum of potential energy of deformation (MPED) method has been used to calculate the framework. The results of theoretical calculation and simulation of the boom section of a crop spraying machine have been compared. The results of analytical calculation have been checked by the simulation of 3D model of the using the program complex «Lira-SAPR», where the finite elements method (FEM) has been implemented. Research limitations/implications: Horizontal components of the shear forces as well as the normal forces and as a consequence the corresponding potential deformation energy are neglected, which has some effect on the accuracy of the calculations. Practical implications: An effective tool for strength analysis with preliminary assessment and diagnostics structures based on the constructed calculation models of stress strain state load-bearing frames of typical geometry with an arbitrarily given distribution of external load. Originality/value: A universal algorithm records of the function of torque and bending moment, as well as the function of potential deformation energy of a spraying machine boom section.
Źródło:
Journal of Achievements in Materials and Manufacturing Engineering; 2021, 105, 1; 33--41
1734-8412
Pojawia się w:
Journal of Achievements in Materials and Manufacturing Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-8 z 8

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