Autor: Stankowski, J. - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: EPR Effect in Magnetic Dependent Dissipation in High Temperature Superconductors
Autorzy:: Stankowski, J.
Tematy:: 74.72.-h
76.30.-v; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2043552.pdf Link otwiera się w nowym oknie
Opis:: Electron paramagnetic resonance in ac dissipation was observed due to the Cooper pairs breaking up to their quasiparticle state. This phenomenon is the result of a flux motion on a pinning centers in high temperature superconducting materials. The detection of ac dissipation was performed in a low ac field (15 and 22 MHz) as well as in microwave range. Vortex motion hysteresis loop with magnetic field modulation of 15 Hz was recorded. Besides V-shaped dependence of ac power dissipation P(B), a direct electron paramagnetic resonance signal related to Cooper pairs → quasiparticle fluctuation was observed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: EPR and MMMA Study of C$\text{}_{60}$ upon K-Doping
Autorzy:: Kempiński, W.
Stankowski, J.
Tematy:: 74.70.Wz
76.30.-v; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1933662.pdf Link otwiera się w nowym oknie
Opis:: EPR and ΜΜMΑ studies of C$\text{}_{60}$ upon K-doping have been performed. Two different and well separated EPR narrow lines were detected for C$\text{}_{60}^{1-}$ and C at temperatures below 100 K. Time dependent changes in the intensities of both and C$\text{}_{60}^{3-}$ lines were observed when the system undergoes an eutectoid transformation. The evolution of superconductivity with two T$\text{}_{c}$ related to different valences (v) of C$\text{}_{60}^{v}$ ion radicals have been found.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: The Influence of the Microwave Power on Josephson Microwave Absorption in High- Temperature Superconductors
Autorzy:: Czyżak, B.
Stankowski, J.
Tematy:: 74.50.+r
74.70.Vy; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1887983.pdf Link otwiera się w nowym oknie
Opis:: The influence of the microwave power on the internal Josephson Junction System (JJS) in granular high T$\text{}_{c}$, superconductors was investigated using EPR methodology. Josephson Microwave Absorption signal was used to monitor local temperature of the Josephson Junction System while the bulk sample temperature was measured by a thermocouple. The effect of the JJS overheating is discussed as the consequence of an interaction between JJS, microwave field and the bulk sample.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Graphenes Bonding Forces in Graphite
Autorzy:: Rozpłoch, F.
Patyk, J.
Stankowski, J.
Tematy:: 73.20.-r
81.05.Uw; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2047742.pdf Link otwiera się w nowym oknie
Opis:: Graphenes bonding forces in graphite are widely known as an example of the van der Waals forces. Well-known experimental facts relative to graphite negate this. A comparison of physical properties of graphite and molecular crystals and metals is shown. A model of dominant weak metallic bonding forces between graphenes is proposed. Brief theoretical background to the model is given.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Magnetic Ground State of Fullerenes
Autorzy:: Koper, A.
Stankowski, J.
Thomas, M.
Tematy:: 75.10.Hk
75.25.+z
36.40.+d; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1930574.pdf Link otwiera się w nowym oknie
Opis:: The classical limit of the effective antiferromagnetic Heisenberg Hamiltonian has been investigated on the series of free clusters (molecules) of C$\text{}_{N}$ (N = 32, 44, 50, 58, 60,, 70 and 84). The valley structures of the frustrated ground states were determined. Moreover, the probability distributions of the spin correlation functions were calculated.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Hierarchical Fast Selection of Intraframe Prediction Mode in HEVC
Autorzy:: Siast, J.
Stankowski, J.
Domański, M.
Tematy:: video coding
high efficiency video coding (HEVC)
intraframe prediction
fast mode selection; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/226081.pdf Link otwiera się w nowym oknie
Opis:: In the new HEVC standard, there are 35 intraframe prediction modes. Therefore, real-time implementations need fast mode pre-selection to reduce the computational load of cost comparison for individual modes. In this paper, a simple technique is proposed to reduce the complexity of the Unified Intra Prediction by decreasing the mode candidate number evaluated in the Rough Mode Decision step. We call this approach hierarchical as we decrease stepwise the angles between the directions of the prediction modes that are tested. Obviously, the fast mode selection results in significant complexity reduction obtained at the cost of choosing a sub-optimum mode related to slightly reduced compression performance. In the paper, it is proposed how to calculate the trade-off between encoder complexity and compression performance, using the ratio of relative coding time reduction and average bitrate increase estimated for constant decoded video quality. Extensive experiments prove that this ratio is much higher for the proposed technique than for many other techniques from the references.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Pseudorotational Averaging of EPR Spectrum of Cu(II)O$\text{}_{5}$ Complex in YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ in Low Temperatures
Autorzy:: Stankowski, J.
Kempiński, W.
Trybuła, Z.
Tematy:: 61.50.-f
74.70.Vy
76.30.Fe; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1891644.pdf Link otwiera się w nowym oknie
Opis:: In low temperatures the condensation of oxygen was found to occur at 05 site in an elementary cell of YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ being the fifth ligand forming the CuO$\text{}_{5}$ complex around Cul copper in chain. This change of coordinantion from CuO$\text{}_{4}$ to CuO$\text{}_{5}$ is the origin of a pseudorotation related to a strong vibronic coupling of two distorted configurations: a tetragonal pyramid C$\text{}_{4v}$ and a trigonal bipyramid D$\text{}_{3h}$, which yields a pseudocubic EPR spectrum in low temperatures. The averaged spectroscopic splitting coefficient is related to a superposition of vibronically coupled orbital states |x$\text{}^{2}$ - y$\text{}^{2}$〉 and |3z$\text{}^{2}$ - r$\text{}^{2}$〉. The averaged spectrum was for the first time observed in low temperatures since the oxygen condensation in YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ at 05 site of the chain occur only when oxygen undergoing fast diffusion among the chains, gets localized with decreasing temperature. The activation energy of oxygen desorption from the 05 site is 36 K.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Free Radicals in K and Rb Admixtured Fullerene C$\text{}_{60}$
Autorzy:: Stankowski, J.
Kempiński, W.
Byszewski, P.
Trybuła, Z.
Tematy:: 76.30.Rn
74.70.Wz; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1929831.pdf Link otwiera się w nowym oknie
Opis:: Molecules of C$\text{}_{60}$ form Van der Waals type crystals. The observations reported here concern EPR investigations of such C$\text{}_{60}$ samples with only a slight amount of Rb or K. Detected defects are (C$\text{}_{60}$)$\text{}^{+}$ or (C$\text{}_{60}$)$\text{}^{y-}$ ion-radicals. A hole (h) or trapped electron (t) are localized on one fullerene ball. In the case of potassium fullerites C$\text{}_{60}$:K the line shape of EPR signal was of the Dysonian form which is characteristic of conducting electrons in metal. The EPR lines of holes (C$\text{}_{60}$)$\text{}^{+}$ are characterized by g$\text{}_{h}$ ≥ g$\text{}_{0}$ whereas for electrons g$\text{}_{t}$ is below the value g$\text{}_{0}$ = 2.0023 characteristic of a free electron (g$\text{}_{t}$ ≤ g$\text{}_{0}$). The EPR linewidth 2ΔB$\text{}_{1s}^{h}$ of the (C$\text{}_{60}$)$\text{}^{+}$ weakly increased with decreasing temperature whereas the EPR linewidth attributed to the electron 2ΔB$\text{}^{t}$$\text{}_{1s}$ significantly decreases with decreasing temperature. The C$\text{}_{60}$:K sample reached superconducting phase below T$\text{}_{c}$ = 11 K which is significantly less than T$\text{}_{c}$ = 16.5 K observed for K$\text{}_{x}$C$\text{}_{60}$ where 2 ≤ x ≤ 4.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: HEVC Encoding Assisted with Noise Reduction
Autorzy:: Stankiewicz, O.
Wegner, K.
Karwowski, D.
Stankowski, J.
Klimaszewski, K.
Grajek, T.
Tematy:: HEVC encoding
encoder control
model selection optimization
noise reduction; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/226110.pdf Link otwiera się w nowym oknie
Opis:: Optimization of encoding process in video compression is an important research problem, especially in the case of modern, sophisticated compression technologies. In this paper, we consider HEVC, for which a novel method for selection of the encoding modes is proposed. By the encoding modes we mean e.g. coding block structure, prediction types and motion vectors. The proposed selection is done basing on noise-reduced version of the input sequence, while the information about the video itself, e.g. transform coefficients, is coded basing on the unaltered input. The proposed method involves encoding of two versions of the input sequence. Further, we show realization proving that the complexity is only negligibly higher than complexity of a single encoding. The proposal has been implemented in HEVC reference software from MPEG and tested experimentally. The results show that the proposal provides up to 1.5% bitrate reduction while preserving the same quality of a decoded video.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Oxygen Deficient YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$: Two Superconducting Phases
Autorzy:: Stankowski, J.
Ślązak, A.
Kempiński, W.
Andrzejewski, B.
Reichel, B.
Plesch, G.
Tematy:: 74.72.-h
74.62.Bf
74.62.-c
74.25.Nf; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2037166.pdf Link otwiera się w nowym oknie
Opis:: A set of oxygen deficient powder and granular samples of YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ ceramics was studied by means of thermogravimetric and magnetically modulated microwave absorption methods. Especially the last method has turned out to be a powerful method, which was used to determine the dependence of critical temperature T$\text{}_{c}$ on the oxygen parameterδ. Using these methods it has been shown that the removing of oxygen evokes the inhomogeneous oxygen distribution in the samples and a change in carrier concentration till to the loss of superconducting properties. A superconducting phase with T$\text{}_{c}$=60 K, which occurs in oxygen deficient YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ sample, is an unstable phase.
Dostawca treści:: Biblioteka Nauki

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