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    Wyświetlanie 1-87 z 87
    Tytuł:
    Magnetic Anisotropy of V$\text{}^{++}$ in CdS
    Autorzy:
    Herbich, M.
    Mac, W.
    Twardowski, A.
    Demianiuk, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1950804.pdf
    Data publikacji:
    1996-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    Opis:
    The magnetization measurements at magnetic field up to 6 T obtained from newly grown hexagonal Cd$\text{}_{1-x}$V$\text{}_{x}$S (x ≈ 0.0004) are presented. The strong anisotropy of magnetization is observed at low temperatures (1.6 < T < 20 K). The data are well described by the crystal field model calculations taking into account static trigonal Jahn-Teller distortion and spin-orbit coupling.
    Źródło:
    Acta Physica Polonica A; 1996, 90, 4; 809-812
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Really First Principles Calculations for CoF₃
    Autorzy:
    Radwanski, R.
    Nalecz, D.
    Krupska, M.
    Piwowarczyk, T.
    Ropka, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1385724.pdf
    Data publikacji:
    2015-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.Fc
    75.10.Dg
    Opis:
    We have derived the low-energy electronic structure of CoF₃, originating from the strongly-correlated 3d⁶ system of the Co³⁺ ion, taking into account the crystal-field interactions, with a relatively weak trigonal distortion, and the relativistic spin-orbit interaction. We have calculated from really first-principles the relevant crystal-field interactions. With the discrete electronic structure for 3d electrons we have described the magnetic properties (the value of the magnetic moment and its direction). The moment direction is determined by the local off-octahedral trigonal distortion proving the single-ion origin of the magnetocrystalline anisotropy. We evaluated the orbital moment and the strength of spin interactions responsible for the formation of the magnetic state. Our studies indicate that calculations of the electronic structure of a 3d compound for the physically-adequate description of the magnetic properties has to be performed at the meV scale.
    Źródło:
    Acta Physica Polonica A; 2015, 127, 2; 391-393
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Crystal Field Theory of Magnetic Behaviour of Er$\text{}_{2}$(SO$\text{}_{4}$)$\text{}_{3}$·8H$\text{}_{2}$O
    Autorzy:
    Gupta, R.
    Ghosh, U. S.
    Basu, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/1945413.pdf
    Data publikacji:
    1996-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Ch
    75.10.Dg
    Opis:
    Using the most rigorous approach of direct diagonalization of the Hamiltonian matrix constructed in the complete basis states (364 in number) of the Er$\text{}^{3+}$ ion the observed magnetic susceptibility and anisotropy data of erbium sulphate octahydrate were simulated and the set of crystal field parameters was evaluated. This procedure automatically includes the effect of intermediate coupling and the J-mixing under the crystal field. It was also demonstrated that such rigorous calculation using complete basis states is necessary in order to evaluate the correct set of parameters which may widely differ from the values obtained from approximate calculations previously performed using partial number of basis states of the ion concerned.
    Źródło:
    Acta Physica Polonica A; 1996, 89, 5-6; 649-655
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Stark and Zeeman Effects in Nd$\text{}_{2}$Fe$\text{}_{14}$B and Pr$\text{}_{2}$Fe$\text{}_{14}$B Intermetallics
    Autorzy:
    Radwański, R. J.
    Franse, J. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1945558.pdf
    Data publikacji:
    1996-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Ej
    75.10.Dg
    Opis:
    The energy level scheme of the Nd$\text{}^{3+}$ and Pr$\text{}^{3+}$ ions in ferromagnetic Nd$\text{}_{2}$Fe$\text{}_{14}$B and Pr$\text{}_{2}$Fe$\text{}_{14}$B intermetallic compounds was evaluated on the basis of all known experiments. In calculations the effect of charge (Stark effect) and spin-dependent (Zeeman effect) interactions were taken into account by means of the crystal-field and molecular-field approximation, respectively. The derived energy level scheme is associated with the removal of the degeneracy of the lowest multiplet given by Hund's rules, i.e. $\text{}^{4}$I $\text{}_{9}\text{}_{/}\text{}_{2}$ (Nd$\text{}^{3+}$) and $\text{}^{3}$H$\text{}_{4}$ (Pr$\text{}^{3+}$). The revealed low-energy electronic structure (<25 meV = 200 cm$\text{}^{-1}$) is associated with many-electron states of the RE$\text{}^{3+}$ ions. Magnetic and electronic properties resulting from this fine structure are compared with all known experimental results. The localized crystal electric field levels exist also in Nd$\text{}_{2}$CuO$\text{}_{4}$, an ionic compound which by doping with Ce becomes high-T$\text{}_{c}$ superconductor, indicating the formation of crystal electric field states independently on the metallic or ionic state.
    Źródło:
    Acta Physica Polonica A; 1996, 90, 1; 223-232
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Atmospheric Pressure Plasma Jet for Mass Spectrometry
    Autorzy:
    Babij, M.
    Gotszalk, T.
    Kowalski, Z.
    Nitsch, K.
    Silberring, J.
    Smoluch, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1198872.pdf
    Data publikacji:
    2014-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    52.50.Dg
    82.80.Ms
    Opis:
    The atmospheric pressure plasma is much advantageous over low pressure plasmas in various aspects, e.g. vacuum-free operation, relative low cost, flexibility of a continuous process. Among various plasmas generated in atmospheric pressure discharges there are cold plasma jets that represent a technology of great application promise (industry, medicine, biology). To generate low-temperature plasmas at atmospheric pressure the dielectric barrier discharge can be used. It is suitable for the atomization of volatile species and can also be served as a ionization source for ambient mass and ion mobility spectrometry. As the discharge is generated in a restricted electrode structure, a plasma jet (plume) is usually formed outside the electrode region (that provides spatial separation of the plasma generation and surface processing regions). The paper presents a source based on a plasma jet established at the end of a capillary dielectric barrier discharge at atmospheric pressure and its application to mass spectrometry. The structure of the jet generator consists of piezoelectric transformer and two concentric and symmetric electrodes, between which the working gas flows at definite rate. Besides the source description early results of spectroscopic analysis are also given.
    Źródło:
    Acta Physica Polonica A; 2014, 125, 6; 1260-1262
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Theoretical Studies on the Local Structure and Spin Hamiltonian Parameters for Single Cu²⁺ Ion in BaF₂
    Autorzy:
    Lin, J.
    Xiao, P.
    Zhao, Y.
    Zhang, B.
    Yang, Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/1398965.pdf
    Data publikacji:
    2016-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    76.30.Fc
    Opis:
    The spin Hamiltonian parameters (g-factors and the hyperfine structure constants) and local structure are theoretically studied for single Cu²⁺ ion in BaF₂ from the high-order perturbation formulae of these parameters for 3d⁹ ions in tetragonally elongated octahedra. In the calculations, the ligand orbital and spin-orbit coupling of the impurity Cu²⁺ are taken into account, based on the cluster approach. Due to the Jahn-Teller effect and size mismatching substitution, the impurity Cu²⁺ is found to be located at a distance of about 0.2 Å from the nearest fluorine plane. The signs of the hyperfine structure constants $A_∥ $ and $ A_⊥ $ are suggested. The theoretical spin Hamiltonian parameters based on the above local structure are in good agreement with the observed values.
    Źródło:
    Acta Physica Polonica A; 2016, 129, 6; 1173-1177
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Systematic Variation of Optical Properties of Alkali Halides: an Ab Initio Study
    Autorzy:
    Gonçalves, G. C.
    Lalic, M. V.
    Malta, O. L.
    Powiązania:
    https://bibliotekanauki.pl/articles/2047877.pdf
    Data publikacji:
    2007-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.20.Dg
    78.20.Ci
    Opis:
    In this paper we study a correlation between the optical properties, electronic structure and anion-cation electronegativity difference in three groups of alkali halides MX (M = Li, Na, K; X = F, Cl, Br, I). The electronic structure was calculated by first-principle, density-functional theory based full-potential linear augmented plane wave method. Then the complex dielectric function was computed, allowing determination of the optical absorption spectra in all compounds, up to incident radiation energy of 40 eV. The results were interpreted in terms of calculated band structures and correlated with the electronegativity difference in each compound, which was estimated on the basis of topological theory of Bader.
    Źródło:
    Acta Physica Polonica A; 2007, 112, 5; 1043-1048
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Effect of Water Accessible Paramagnetic Ions on Subcellular Structures Formed in Developing Wheat Photosynthetic Membranes as Observed by NMR and by Sorption Isotherm
    Autorzy:
    Harańczyk, H.
    Leja, A.
    Strzałka, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/2044747.pdf
    Data publikacji:
    2006-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    82.56.Na
    87.16.Dg
    Opis:
    The rehydration from the gaseous phase of the developing native or EDTA-washed from unbound and loosely bound paramagnetic ions wheat thylakoid membrane lyophilizate was investigated using hydration kinetics, sorption isotherm, and high power proton relaxometry. Hydration time courses are single exponential for all target humidities. The sorption isotherm is well fitted by the Dent model, with the mass of water saturating primary binding sites equal toΔ M/m$\text{}_{ }$0=0.024 and 0.017 for native and EDTA-washed membranes, respectively. Proton free induction decays distinguish: (i) a Gaussian component, S$\text{}_{0}$, coming from protons of solid matrix of lyophilizate; (ii) a Gaussian component, S$\text{}_{1}$, from water bound to the primary water binding sites in proximity of water accessible paramagnetic ions; (iii) an exponentially decaying contribution, $L$\text{}_{1}$$, from water tightly bound to lyophilizate surface; and (iv) exponentially decaying loosely bound water pool, L$\text{}_{2}$. Sorption isotherm fitted to NMR data shows a significant contribution of water "sealed" in membrane structures (Δ M$\text{}_{s}$/m$\text{}_{0}$=0.052 for native and 0.061 for EDTA-washed developing membranes, respectively).
    Źródło:
    Acta Physica Polonica A; 2006, 109, 3; 389-398
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Bound Water Structure on the Surfaces of Usnea antarctica as Observed by NMR and Sorption Isotherm
    Autorzy:
    Harańczyk, H.
    Pietrzyk, A.
    Leja, A.
    Olech, M. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2044769.pdf
    Data publikacji:
    2006-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    82.56.Na
    87.16.Dg
    Opis:
    Hydration courses and proton free induction decays are recorded at 30 MHz for Usnea antarctica thalli hydrated from gaseous phase. NMR data combined with gravimetry allow one to distinguish two fractions of tightly bound water, and loosely bound/free water pool. No water fraction "sealed" in thallus structures is present in U. antarctica.
    Źródło:
    Acta Physica Polonica A; 2006, 109, 3; 411-416
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Crystal-Field Interactions in $RPd_2Al_3$ Intermetallics (R = Pr, Nd, Sm, and U)
    Autorzy:
    Radwanski, R.
    Nalecz, D.
    Ropka, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1374347.pdf
    Data publikacji:
    2014-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Ej
    75.10.Dg
    Opis:
    Magnetic and electronic properties of $NdPd_2Al_3$ have been nicely described with the $Nd^{3+}$ ions within the crystal-field theory revealing that all Nd atoms equally contribute to the temperature dependence of the paramagnetic susceptibility and of the heat capacity with the λ-peak. We consistently described paramagnetic and magnetically-ordered state. The fine electronic structure of the $Nd^{3+}$ ion nicely correlates with the electronic structure of the $U^{3+}$ ion in $UPd_2Al_3$ giving strong evidence for the trivalent uranium state in the isostructural heavy-fermion superconductor $UPd_2Al_3$.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 4a; A-32-A-35
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigations on the EPR Parameters of $KMgF_3$:$Cr^{+}$
    Autorzy:
    Kuang, M.
    Wu, S.
    Hu, X.
    Li, G.
    Zu, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1365348.pdf
    Data publikacji:
    2014-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    76.30.Fc
    Opis:
    The electron paramagnetic resonance parameters (i.e., g factor, hyperfine structure constant and superhyperfine parameters) of $KMgF_3$:$Cr^{+}$ are theoretically investigated from the perturbation formulae of these parameters for an octahedral $3 d^5$ cluster. As for the calculations of g factor and hyperfine structure constant, both the contributions from the crystal-field and charge transfer mechanisms are included based on the cluster approach. The metal to ligand charge transfer contribution to the g-shift Δg ( ≈ g-2.0023) is the same (negative) in sign and much larger in magnitude as compared to the crystal-field one. The conventional argument that the charge transfer contributions to zero-field splittings are negligible for $3 d^5$ ions in fluorides is no longer suitable for Δg analysis of $KMgF_3$:$Cr^{+}$ due to the dominant second-order charge transfer perturbation term. The charge transfer contribution to hyperfine structure constant exhibits the same sign and about 4% of the crystal-field one. The unpaired spin densities of the fluorine 2s, 2pσ and 2pπ orbitals are quantitatively acquired from the relationships with the relevant molecular orbital coefficients using the uniform model. The present treatments are superior to the previous calculations of directly fitting the experimental superhyperfine parameters.
    Źródło:
    Acta Physica Polonica A; 2014, 125, 5; 1224-1228
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A Simple Localized-Itinerant Model for PrAl$\text{}_{3}$: Crystal Field and Exchange Effects
    Autorzy:
    Von Ranke, P. J.
    Palermo, L.
    Da Silva, X. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1891680.pdf
    Data publikacji:
    1991-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    75.30.Cr
    Opis:
    We present a simple magnetic model for PrAl$\text{}_{3}$. The effects of crystal field are treated using a reduced set of levels and the corresponding wave functions are extracted from the actual crystal field levels of Pr$\text{}^{+3}$ in a hexagonal symmetry. The exchange between 4f- and conduction-electrons are dealt within a molecular field approximation. An analytical magnetic state equation is derived and the magnetic behaviour discussed. The parameters of the model are estimated from a fitting of the inverse susceptibility of PrAl$\text{}_{3}$ given in the literature.
    Źródło:
    Acta Physica Polonica A; 1991, 80, 4; 583-590
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Passive filter design for three-phase inverter interfacing in distributed generation
    Autorzy:
    Ahmed, K. H.
    Finney, S. J.
    Williams, B. W.
    Powiązania:
    https://bibliotekanauki.pl/articles/262578.pdf
    Data publikacji:
    2007
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie
    Tematy:
    DG
    inverter
    grid connected
    filtering
    damping
    harmonics
    Opis:
    With the growing use of inverters in distributed generation, the problem of injected harmonics becomes critical. These harmonics require the connection of low pass filters between the inverter and the network. This paper presents a design method for the output LC filter in grid coupled applications in distributed generation systems. The design is according to the harmonics standards that determine the level of current harmonics injected into the grid network. Analytical expressions for the maximum inductor ripple current are derived. The filter capacitor design depends on the allowable level of switching components injected into the grid. Different passive filter damping techniques to suppress resonance affects are investigated and evaluated. Simulated results are included to verify the derived expressions.
    Źródło:
    Electrical Power Quality and Utilisation. Journal; 2007, 13, 2; 49-58
    1896-4672
    Pojawia się w:
    Electrical Power Quality and Utilisation. Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Impact of Vanadium(IV)-Oxy Acetylacetonate and Vanadium(III) Acetylacetonatel on the DPPC Liposome Membranes: EPR Studies
    Autorzy:
    Man, D.
    Mrówka, I.
    Wójcik, A.
    Pytel, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032414.pdf
    Data publikacji:
    2017-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    87.16.Dg
    87.64.kh
    87.80.Lg
    Opis:
    The effect of vanadium (IV)-oxy acetylacetonate (V4) and vanadium(III) acetylacetonate (V3) on the liposome membranes formed of synthetic lecithin (DPPC) was presented in this paper. Liposomes were formed during the sonication of DPPC lecithin in an aqueous medium. The concentration of the vanadium compounds changed in the range of 0% to 2.4% in molar ratio to the lecithin. The EPR technique made use of three spin probes penetrating the different areas of the membrane (as follows: TEMPO, 16-DOXYL stearic acid methyl ester, stearic acid 5-DOXYL methyl ester). TEMPO probe penetrates the interphase water-lipid (partition parameter F), the probe 16-DOXYL locates in the middle of the lipid bilayer (rotational correlation time τ), the probe 5-DOXYL gives a picture of membrane fluidity (the order parameter) just below the polar head groups. The results of our research showed the following conclusions. The change of membrane fluidity, as a function of admixture concentration, was dependent on the type of additives. TEMPO probe recorded an increase in liquidity interphase water-lipid for both admixtures: V3 and V4. 16-DOXYL probe indicated that the admixture V3 increases the fluidity in the center of the lipid bilayer. Admixture V4 significantly less impacted on the change of the membrane middle. The 5-DOXYL probe did not influence on the membrane surface portion, there were not observed significant changes under the impact of admixtures. V3 showed stronger impact on membrane fluidity.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 1; 52-56
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Three localized f electrons in UPd₂Al₃ and in UGe₂ intermetallics
    Autorzy:
    Radwanski, R.
    Nalecz, D.
    Ropka, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1062036.pdf
    Data publikacji:
    2016-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Ej
    75.10.Dg
    75.30.Gw
    Opis:
    We have calculated the strength of the excitations between the crystal-field states which are in agreement with inelastic-neutron-scattering results. This agreement confirms the existence in the heavy-fermion superconductor UPd₂Al₃ the crystal-field electronic structure being the finger-print of the U^{3+} ions with three localized f electrons forming strongly-correlated atomic-like quantum system 5f³. The ionic integrity and the low-energy crystal-field electronic structure is preserved in this metallic system in the meV scale as has been postulated in the Quantum Atomistic Solid State theory (QUASST). We provide preliminary results with the U^{3+} ion in UGe₂ showing the ground-state eigenfunction which reproduces the ordered magnetic-moment value of 1.48 μ_{B}. This moment is composed from the dominant orbital contribution (2.6 μ_{B}) and the opposite spin moment (1.12 μ_{B}).
    Źródło:
    Acta Physica Polonica A; 2016, 130, 2; 545-550
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Impact of Plesiomonas shigelloides strain CNCTC 144/92 lipopolysaccharide on DPPC liposome membranes: EPR method
    Autorzy:
    Man, D.
    Pytel, B.
    Pisarek, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/1054999.pdf
    Data publikacji:
    2017-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    87.16.Dg
    87.64.kh
    87.80.Lg
    Opis:
    Membrane fluidity measurements were performed for synthetic DPPC liposomes sonicated in aqueous solution and doped by Plesiomonas shigelloides strain CNCTC 144/92 (serotype O74:H5) lipopolysaccharide (LPS) extracted from the phenol (LPS_{PhOH}) and water (LPS_{H₂O}) phases. Concentrations of LPS in relation to DPPC ranged from 0 to 1.4% (molar ratio). The EPR spin probe method was used to describe physicochemical properties of different regions of the lipid bilayer. Since TEMPO spin probe dissolves both in the hydrophobic region of the membrane and in an aquatic environment it is possible to determine the spectroscopic partition parameter F, indicating the changes that occur in the water-lipid interface. The 16-DOXYL probe distributed in the middle of the lipid bilayer makes it possible to obtain the rotational correlation time τ parameter, which provides information about fluidity changes in the liposome membrane. Here we report that increasing concentrations (mainly in the range of 0.4-0.8%) of investigated LPS_{PhOH} and LPS_{H₂O} significantly influence spectroscopic parameters (F and τ). The surface area of the DPPC liposomes membranes was affected predominantly by LPS_{H₂O} while the lipid bilayer was most influenced by LPS_{PhOH}.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 1; 77-80
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Relaxation in Metallic Glass $Ni_{36.5}Zr_{63.5}$
    Autorzy:
    Sulejmanović, S.
    Mihać, T.
    Bikić, S.
    Bajrović, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/1537960.pdf
    Data publikacji:
    2010-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.dg
    64.70.pe
    72.15.Cz
    Opis:
    The metallic glass ribbons of $Ni_{36.5}Zr_{63.5}$ were prepared by melt spinning. The samples have a large frozen-in structural disorder and in comparison with their crystalline state, a very high electrical resistivity. They are metastable and they relax structurally towards more stable state whenever atoms attain noticeable mobility. As the most structurally sensitive property the electrical resistivity of these samples was used to follow the relaxation process from room temperature to 673 K. To complete the investigation of structural relaxation the electrical resistance of as-quenched, annealed and about twenty years aged $Ni_{36.5}Zr_{63.5}$ samples was measured in the temperature range from 77 K to 275 K. The obtained results were presented graphically.
    Źródło:
    Acta Physica Polonica A; 2010, 117, 5; 817-819
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Structural and Electronic Properties of BaO under Epitaxial Strains: First-Principles Calculations
    Autorzy:
    Yang, Xiong
    Wang, Ying
    Chen, Yifei
    Yan, Huiyu
    Powiązania:
    https://bibliotekanauki.pl/articles/1191222.pdf
    Data publikacji:
    2016-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.20.Dg
    71.70.Fk
    71.15.Mb
    Opis:
    The structural and electronic properties of alkaline-earth oxide BaO under epitaxial strains are investigated using a first principles density functional theory. The electronic structure is particularly sensitive to the compressive or tensile strain, e.g., the splitting of energy band, the increase of the total density of state, and the shift of the partial density of states. Especially, the trends in the variation of the optical band gap are predicted by two different exchange-correlation potential schemes. Our results indicate that the optical band gaps undergo a decrease for both compressive and tensile strains.
    Źródło:
    Acta Physica Polonica A; 2016, 129, 1; 64-68
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fermi Surface-Brillouin Zone Interactions in 2/1-2/1-2/1 Bergman-Type Approximant $Na_{27}Au_{27}Ga_{31}$
    Autorzy:
    Mizutani, U.
    Sato, H.
    Inukai, M.
    Zijlstra, E.
    Lin, Q.
    Corbett, J.
    Miller, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/1373341.pdf
    Data publikacji:
    2014-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.23.Ft
    71.20.Dg
    71.15.Mb
    Opis:
    The X-ray diffraction studies on a newly synthesized $Na_{26}Au_{25}Ga_{29}$ single crystal revealed the formation of a single phase 2/1-2/1-2/1 Bergman-type approximant and the presence of Au/Ga mixed occupancies in its unit cell containing 680 atoms. The structure model of the 2/1-2/1-2/1 approximant with composition $Na_{27}Au_{27}Ga_{31}$ was constructed by eliminating the chemical disorder with a minimum sacrifice of composition displacement. The full potential linearized augmented plane wave electronic structure calculations with subsequent full potential linearized augmented plane wave-Fourier analysis were performed for the 2/1-2/1-2/1 approximant $Na_{27}Au_{27}Ga_{31}$ with space group Pa3̅. The square of the Fermi diameter $(2k_{F})^2$, electrons per atom ratio e/a and the critical reciprocal lattice vector $|G|^2$ are determined. A shallow pseudogap at the Fermi level was interpreted as originating from interference of electrons having $(2k_{F})^2$=109.2±1.0 with sets of lattice planes with $|G|^2$'s centered at 108. The effective e/a value for the compound is found to be 1.76 in good agreement with 1.73 derived from a composition average of $(e/a)_{Na}$=1.0, $(e/a)_{Au}$=1.0 and $(e/a)_{Ga}$=3.0.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 2; 535-538
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Composite Particles Formation and Behaviour in Al-Li Alloys Alloyed by Sc (Zr) under Heat Treatment and Severe Plastic Deformation
    Autorzy:
    Molebnyi, O.
    Berezina, A.
    Kotko, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1402081.pdf
    Data publikacji:
    2015-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.dg
    81.07.Bc
    81.10.Fg
    Opis:
    The mechanism and kinetics of Al₃Li/Al₃Sc composite particles formation during aging of triple Al-Li-Sc alloys were studied. The particles of such type consist of two isomorphic phases, ordered by L1₂ type. Composite particles in Al-Li-Sc are formed by epitaxial nucleation of δ' (Al₃Li) phase on pre-existing Al₃Sc precipitates at low temperature aging in the area of existence of Al₃Li phase, and form uniform shell around them. The motive force of such heterostructure formation is the minimization of total surface, elastic and chemical energy of the alloy. Dark-field transmission electron microscopy images of such composite particles taken from superlattice reflex 100 are composed of a dark core surrounded by a bright shell. The mutual diffusion of Li and Sc during the aging of Al-Li-Sc alloys is observed. The dark-field transmission electron microscopy image of the composite particle obtained from superlattice reflection became transparent after continuous natural aging of Al-Li-Sc alloys. The presence of the particle in Al matrix can be only seen due to decoration by secondary precipitations of δ' (Al₃Li) phase. Composition analysis of such transparent particles was carried out using two-beam kinematical theory of electron diffraction. Such composite particles with transparent cores remain in Al matrix even after severe plastic deformation of Al-Li-Sc alloy.
    Źródło:
    Acta Physica Polonica A; 2015, 128, 4; 564-569
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thermal Stability and Mechanism of Thermally Induced Crystallization of $Fe_{73.5}Cu_1Nb_3Si_{15.5}B_7$ Amorphous Alloy
    Autorzy:
    Vasić, M.
    Minić, D.
    Blagojević, V.
    Žák, T.
    Pizúrová, N.
    David, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1402117.pdf
    Data publikacji:
    2015-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.dg
    64.70.kd
    64.70.pe
    Opis:
    Investigation of thermal stability of the alloy revealed stepwise crystallization process, manifested by two distinct complex exothermic peaks in differential scanning calorimetry curves. Kinetic parameters of individual crystallization steps were found using the Kissinger and Vyazovkin methods. Structural characterization of thermally treated samples showed formation of different iron-based phases including α-Fe(Si), Fe₂B, Fe₁₆Nb₆Si₇ and Fe₂Si and some metastable intermediary species. Morphology characterization of the surface and cross-section of the thermally treated samples showed granulated structure composed of several different phases and indicated occurrence of impingement effects during crystal growth. Value of estimated lifetime suggested very high stability against crystallization at room temperature and abrupt decrease of lifetime with temperature increase.
    Źródło:
    Acta Physica Polonica A; 2015, 128, 4; 657-660
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Formation of Accelerated Particle Beam in Isochronous Cyclotron
    Autorzy:
    Voronin, A.
    Partyka, J.
    Aldibekova, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1381861.pdf
    Data publikacji:
    2014-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    29.27.Bd
    29.20.dg
    41.85.-p
    Opis:
    In the paper there are given calculated and experimental data which allow to form necessary beam parameters for a precise experiment in nuclear physics. An intensity of a beam extracted from an isochronous cyclotron acceleration chamber ($E_{p}$ = 30 MeV) can reach 15 μA with an energy spread of 3 × $10^{-3}$. Accelerated ion beams of such kind are widely applicable in nuclear physical experiments.
    Źródło:
    Acta Physica Polonica A; 2014, 125, 6; 1408-1411
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Angular Distortion around $Cr^{3+}$ Ions Doped Diammonium Hexaaqua Magnesium Sulphate Single Crystal
    Autorzy:
    Ciresan, M.
    Vaida, M.
    Avram, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/1815473.pdf
    Data publikacji:
    2007-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    76.30.-v
    71.70.Ch
    Opis:
    The aim of the present study is to explain the local distortion around $Cr^{3+}$ ions doped in the title crystal using the latest experimental data regarding optical and EPR spectra. We calculated $g_ǁ$, $g_⊥$, and D spin-Hamiltonian parameter as function of angle between the $C_3$ axis and metal-ligand chemical bond in local distorted octahedral cluster $[CrO_6]^{9-}$ formed after doped crystal. The method is based on the single spin-orbit coupling parameter model, in the cluster approach using Macfarlane high order perturbation formulae. The results compared with experimental data give a reasonable agreement.
    Źródło:
    Acta Physica Polonica A; 2007, 112, 5; 835-839
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Heisenberg Model of a Ferromagnetic Monolayer Deposited on a Non-Magnetic Bulk Substrate
    Autorzy:
    Jaworski, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/1810418.pdf
    Data publikacji:
    2009-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    75.10.Hk
    75.10.Jm
    Opis:
    A model describing a Heisenberg ferromagnetic monolayer (in a magnetic field) interacting with its non-magnetic bulk substrate is formulated. We use reduced-density operators to show that physical properties of the monolayer are affected by its interaction with the environment. Particularly the influence of the substrate lattice vibrations on the monolayer exchange parameter is examined. The Gaussian-type orbitals were used to calculate the distance dependence of the exchange parameter and the many-body Green functions to calculate the temperature dependence of the magnetization. Finally, the influence of the Debye temperature of the substrate on the magnetization of the monolayer is depicted. Although the resultant effect is not prominent, we state that interaction of ultrathin magnetic films with their environment has to be taken into account in the construction of the reduced-density operator.
    Źródło:
    Acta Physica Polonica A; 2009, 115, 1; 171-173
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dynamic Crystal Field in CePb$\text{}_{3}$
    Autorzy:
    Lipiński, S.
    Szajek, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2012928.pdf
    Data publikacji:
    2000-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    75.20.Hr
    75.30.Mb
    Opis:
    The crystal field of valence fluctuating systems is time dependent due to f-electron transfers to the conduction band. We examine the effects of crystal field fluctuations on the neutron spectra, the specific heat and susceptibility of CePb$\text{}_{3}$.
    Źródło:
    Acta Physica Polonica A; 2000, 97, 1; 245-248
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of $\text{}^{172}$Yb in Perturbed Angular Correlation Measurements
    Autorzy:
    Rams, M.
    Królas, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/2028939.pdf
    Data publikacji:
    2001-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.80.+y
    75.10.Dg
    75.30.Mb
    Opis:
    The radioactive decay of $\text{}^{172}$Lu → $\text{}^{172}$Yb appears to be suitable for time-differential perturbed angular correlation measurements of quadrupole interaction. The technique was applied to study various phenomena in three compounds: Yb$\text{}_{3}$S$\text{}_{4}$, YbPO$\text{}_{4}$, Yb$\text{}_{2}$Co$\text{}_{3}$Ga$\text{}_{9}$. We were able to distinguish between Yb$\text{}^{2+}$ and Yb$\text{}^{3+}$ ions occupying different positions in the crystal lattice of Yb$\text{}_{3}$S$\text{}_{4}$. Crystal electric field parameters reproduced the temperature dependence of the quadrupole interaction of Yb in YbPO$\text{}_{4}$. Finally, the influence of hybridization on the 4f quadrupole moment in Yb$\text{}_{2}$Co$\text{}_{3}$Ga$\text{}_{9}$ is evidenced.
    Źródło:
    Acta Physica Polonica A; 2001, 100, 5; 687-697
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thermodynamic Properties of Geometrically Frustrated S=1/2 XY Antiferromagnet $Er_{2}Sn_{2}O_{7}$
    Autorzy:
    Al Ghamdi, N.
    Orendáčová, A.
    Pavlík, V.
    Orendáč, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1368676.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    75.50.Ee
    75.30.Sg
    Opis:
    The magnetic susceptibility, specific heat and entropy of geometrically frustrated S=1/2 XY antiferromagnet $Er_{2}Sn_{2}O_{7}$ are reported. It is shown, that temperature dependence of magnetic susceptibility above nominally 10 K is governed by crystal field effects. Systematic study of specific heat in magnetic fields up to 7 T enabled the estimation of exchange coupling, J/k<<4.6 K. Investigation of isothermal change of magnetic entropy upon magnetization from 1 T to 7 T revealed the absence of enhanced magnetocaloric effect. The obtained results suggest that frustration parameter f ≈140 proposed for $Er_{2}Sn_{2}O_{7}$ earlier may be significantly overestimated.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 264-265
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Formation of Dislocation Structure in LiF Crystals Irradiated with Swift Heavy Ions under Oblique Incidence
    Autorzy:
    Russakova, A.
    Akilbekov, A.
    Dauletbekova, A.
    Baizhumanov, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1365710.pdf
    Data publikacji:
    2014-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    42.88.+h
    61.80.Jh
    71.20.Dg
    Opis:
    The structural modifications of LiF irradiated with swift heavy ions under oblique angles have been investigated using AFM, SEM, chemical etching, nanoindentation and optical absorption spectroscopy. LiF crystals were irradiated under incidence angles of 30 and 70 degrees with 2.2 GeV Au (fluence 5 × $10^{11}$ ions $cm^{-2}$) and 150 MeV Kr ions (fluence $10^{12}-10^{14}$ ions $cm^{-2}$). Structural study on sample cross-sections shows that two damage regions, (1) nanostructured zone and (2) dislocation rich zone, which are typical for irradiations at normal incidence, appear also in samples irradiated under oblique angles. However in the latter case a more complex structure is formed that leads to stronger ion-induced hardening.
    Źródło:
    Acta Physica Polonica A; 2014, 125, 6; 1257-1259
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Anisotropic Magnetic Susceptibility of Neodymium Substituted SrLaAlO$\text{}_{4}$ Crystals
    Autorzy:
    Fink-Finowicki, J.
    Puźniak, R.
    Baran, M.
    Jabłoński, R.
    Berkowski, M.
    Pajączkowska, A.
    Szymczak, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1931256.pdf
    Data publikacji:
    1994-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Hx
    75.10.Dg
    71.70.Ch
    Opis:
    The uniaxial anisotropy of magnetic properties of SrLa$\text{}_{1-x}$Nd$\text{}_{x}$AlO$\text{}_{4}$ single crystals (x = 0.01 and 0.05) was found from the measurements of temperature dependencies of magnetic susceptibility. Results of measurements, with magnetic field along a- and c-axis, are compared with the similar data obtained for CaNdAlO$\text{}_{4}$ crystal. The successful description of experimental data was done in frames of the crystal field approximation. The anisotropy of magnetic susceptibility appears due to crystal field acting on magnetic neodymium ions in a system without exchange interactions.
    Źródło:
    Acta Physica Polonica A; 1994, 85, 3; 633-637
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Canonization and Diagonalization of an Infinite Dimensional Noncanonical Hamiltonian System: Linear Vlasov Theory
    Autorzy:
    Morrison, P. J.
    Shadwick, B. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1931280.pdf
    Data publikacji:
    1994-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    52.25.Dg
    52.25.Mq
    52.35.Fp
    Opis:
    The Vlasov-Poisson equation, which is an infinite dimensional non-canonical Hamiltonian system, is linearized about a stable homogeneous equilibrium. Canonical variables for the resulting linear system are obtained. A coordinate transformation is introduced that brings the system, which possesses a continuous spectrum, into the action-angle form where the linearized energy is diagonal.
    Źródło:
    Acta Physica Polonica A; 1994, 85, 4; 759-769
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Binary Phase Diagram of Water/Brij58 Studied by SAXS
    Autorzy:
    Fall, S.
    Pattier, B.
    Benyayia, L.
    Gibaud, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1490051.pdf
    Data publikacji:
    2012-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.30.-t
    61.05.C-
    64.70.dg
    Opis:
    The phase diagram of the binary water/Brij58 system has been studied at constant temperature T = 20°C first by simple optical observation and then by small angle X-ray scattering. The small angle X-ray scattering patterns in the isotropic diluted phase are analyzed in a quantitative way by refining the experimental measurements with a model assuming hard spherical micelles in interaction. The micelles are described by a poly dispersed core-shell model and the interaction by the Perkus-Yevick hard-sphere model. The fitted parameters are analyzed in detail to determine the way polyoxyethylene blocks are hydrated with respect to the volumic fraction of water. In the more concentrated regime, the crystalline phases that are identified are the Fm3m cubic, the 2D hexagonal and the lamellar phases. The structural parameters that describe each phases are analyzed and commented. The small angle X-ray scattering study is complemented by the determination of the temperature dependent liquid-solid transition by rheology.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 2; 388-396
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Gaussian Fluctuations of Two Molecular Fields in the Blume-Emery-Griffiths Model
    Autorzy:
    Jaworski, W.
    Jacyna-Onyszkiewicz, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1505093.pdf
    Data publikacji:
    2011-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    75.10.Hk
    75.10.Jm
    Opis:
    The Blume-Emery-Griffiths model for spins S=1 in a bilayer with z=5 nearest neighbours is studied with the use of Gaussian fluctuations approximation. The fluctuations of two molecular fields, connected with two order parameters, are introduced. Their influence on phase diagrams for non-negative values of the biquadratic coupling constant is taken under consideration. The results are compared with those obtained by the mean-field approximation and discussed.
    Źródło:
    Acta Physica Polonica A; 2011, 119, 6; 846-849
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigations on the Anisotropic g Factors of the $Ni^{3+}$ Site in $La_2Ni_{0.5}Li_{0.5}O_4$
    Autorzy:
    Kuang, M.
    Wu, S.
    Zhang, Z.
    Song, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1400149.pdf
    Data publikacji:
    2013-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.Fc
    71.70.Ch
    75.10.Dg
    Opis:
    The anisotropic g factors $g_{∥}$ and $g_{⊥}$ of $La_2Ni_{0.5}Li_{0.5}O_4$ are theoretically investigated using the perturbation formulae of the g factors for a low spin $(S=1//2) 3d^7$ ion in tetragonally elongated octahedra. The studied $Ni^{3+} (3d^7)$ center arises from the original $Ni^{2+}$ capturing one hole by $Li^{+}$ doping. The positive anisotropy $\Delta g (= g_{⊥}-g_{∥})$ can be ascribed to the lowest $\text{}^2 A_{1g}$ state due to the obvious (about 0.14 Å) tetragonal elongation of the oxygen octahedron around the $Ni^{3+}$ site via the Jahn-Teller effect, and the effective magnetic moment is also interpreted in a uniform way. The calculated results show good agreement with the experimental data, and the imperfection of the previous studies based on various adjusted tetragonal energy splittings without correlating to the local structure of the magnetic center is thus overcome in this work.
    Źródło:
    Acta Physica Polonica A; 2013, 123, 4; 734-736
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigations on the Spin-Hamiltonian Parameters and Local Structure of the Orthorhombic $Cu^{2+}$ Center in $PbTiO_3$ Crystal
    Autorzy:
    Chao-Ying, Li
    Li-Bin, Cheng
    Xue-Mei, Zheng
    Powiązania:
    https://bibliotekanauki.pl/articles/1400511.pdf
    Data publikacji:
    2015-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.Fc
    75.10.Dg
    71.70.Ch
    Opis:
    The spin-Hamiltonian parameters (the g factors $g_{i}$ and the hyperfine structure constants $A_{i}$, i = x, y, z) and local structure of the $Cu^{2+}$ center in $PbTiO_{3}$ are theoretically studied by using the perturbation formulae of these parameters for a $3d^{9}$ ion in an orthorhombically elongated octahedra. The orthorhombic center is attributed to $Cu^{2+}$ occupying the host $Ti^{4+}$ site associated with a nearest-neighbouring oxygen vacancy $V_{O}$ along the c-axis, and the impurity $Cu^{2+}$ off-center displacement $\Delta Z_{L}$ ( ≈0.18 Å) is smaller than that of the host $Ti^{4+}$ site ($\Delta Z_{H}$≈ 0.3 Å). Meanwhile, the planar $Cu^{2+}-O^{2-}$ bonds are found to experience the relative variation ΔR ( ≈ 0.098 Å) along the a- and b-axes, respectively, due to the Jahn-Teller effect and the size mismatching substitution of $Ti^{4+}$ by $Cu^{2+}$. The theoretical spin-Hamiltonian parameters based on the above defect structure agree well with the observed values.
    Źródło:
    Acta Physica Polonica A; 2015, 127, 6; 1671-1675
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Decomposition Processes in the Anomalous Supersaturated Solid Solution of Binary and Ternary Aluminium Alloys Alloyed with~Sc and~Zr
    Autorzy:
    Berezina, A.
    Monastyrska, T.
    Molebny, O.
    Nosenko, V.
    Kotko, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1418937.pdf
    Data publikacji:
    2012-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.dg
    81.07.Bc
    81.10.Fq
    Opis:
    Decomposition of supersaturated solid solution of aluminium alloys alloyed with Sc and Zr have been studied in the work. The binary hypereutectic Al-Sc alloys, hyperperitectic Al-Zr alloys and ternary Al-Sc-Zr alloys were chosen. Alloys were obtained by the melt-spinning. Melts were quenched from temperatures of T = 1000C and T = 1400°C. The crystallization of anomalously supersaturated solid solution ($T_\text{quen.}$ = 1400°C) or the crystallization with the formation of "fan" structure ($T_\text{quen.}$ = 1000°C) are possible. The decomposition of anomalously supersaturated solid solution is continuous, with the precipitation of nanosized spherical $Al_3X$ (X = Sc, Zr) particles. The loss of thermal stability of Al-Sc alloys is due to the loss of coherence of the strengthening $Al_3Sc$ phase. In Al-Zr alloys the loss of strength is due to the formation of a stable tetragonal $DO_{23}$-ordered $Al_3Zr$ phase. After co-alloying of Al by Sc and Zr a bimodal grained structure was observed for the hypereutectic ternary alloy ($T_\text{quen.}$ = 1400°C). Nanosized grains of 50-60 nm were present on the boundaries of 1-2 μm large-sized grains. Transmission electron microscopy shows the formation of nanocomposite $Al_3Zr//Al_3Sc$ particles. The formation of $Al_3Zr$ shell changes the nature of the interfacial fit of the particle with the matrix and slows down the decomposition during the coalescence.
    Źródło:
    Acta Physica Polonica A; 2012, 122, 3; 539-543
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of Local Potential on Exciton Splitting in Highly Diluted Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te
    Autorzy:
    Kłopotowski, Ł.
    Herbich, M.
    Mac, W.
    Stachow-Wójcik, A.
    Twardowski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1968234.pdf
    Data publikacji:
    1997-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    75.50.Pp
    71.70.Gm
    Opis:
    We investigated magnetoreflectance and magnetization of highly diluted bulk Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te crystals 0.2% ≤ x ≤ 10%. The exchange constant in terms of mean field approximation and virtual crystal approximation (the ratio of the heavy hole exciton splitting to mean spin per unit cell) was evaluated and found x-dependent. This deviation from the mean field approximation and virtual crystal approximation prediction is caused by the local potential introduced by Mn ions. We discuss the problem within a Wigner-Seitz approach and within a model of magnetic and chemical disorder based on the alloy theory.
    Źródło:
    Acta Physica Polonica A; 1997, 92, 4; 837-840
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Interferometry and Dissipative Optics with Atoms
    Autorzy:
    Szriftgiser, P.
    Guéry-Odelin, D.
    Desbiolles, P.
    Dalibard, J.
    Arndt, M.
    Steane, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1968538.pdf
    Data publikacji:
    1998-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    03.75.Dg
    32.80.Pj
    42.50.Vk
    Opis:
    We have designed a gravitational cavity for ultra-cold atoms using an atomic mirror made from an evanescent laser wave. By a temporal variation of the evanescent wave intensity, we have realized various atom optics components such as temporal slits and phase modulators. We have also designed an atom interferometer using this cavity which proves that the coherence of the de Broglie waves can be preserved during the bounce of the atoms on the mirror. Finally we show that an efficient cooling of the atoms inside the cavity can be achieved using a Sisyphus process during the bounce.
    Źródło:
    Acta Physica Polonica A; 1998, 93, 1; 197-209
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Research on the Spin-Hamiltonian Parameters and Local Structure for the Tetragonal $Mo^{5+}$ Centers in $CaWO_{4}$ Crystal
    Autorzy:
    Mei, Y.
    Zheng, W.
    Wei, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/1377649.pdf
    Data publikacji:
    2014-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.He
    71.70.Ch
    75.10.Dg
    Opis:
    The spin-Hamiltonian parameters (g factors $g_{∥}$, $g_{⊥}$ and hyperfine structure constants $A_{∥}(A)$, $A_{⊥}(A)$, $A_{∥}(B)$ and $A_{⊥}(B)$, A(A) and A(B) belonging to isotopes $\text{}^{95}Mo^{5+}$ and $\text{}^{97}Mo^{5+})$ of $Mo^{5+}$ ion at the tetragonally-compressed tetrahedral $W^{6+}$ site in $CaWO_4$ crystal are calculated from the high-order perturbation formulae based on the two-mechanism model, where besides the contributions to spin-Hamiltonian parameters due to the crystal-field mechanism concerning the crystal-field excited states in the extensively-applied crystal-field theory, those due to charge-transfer mechanism concerning charge-transfer excited states (which are omitted in crystal-field theory) are included. The calculated results are in reasonable agreement with the experimental values. The calculations show that for the high-valence state $d^{n}$ ions (e. g., $Mo^{5+}$ considered) in crystals, the contributions due to charge-transfer mechanism should be taken into account in the studies of spin-Hamiltonian parameters. The local structure of $Mo^{5+}$ center in $CaWO_4$ crystal due to the impurity-induced local lattice relaxation is estimated from the calculations. The results are discussed.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 6; 1275-1279
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Specific Heat and the Ground State of NiO
    Autorzy:
    Radwanski, R.
    Ropka, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1812327.pdf
    Data publikacji:
    2008-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.10.-w
    75.10.-b
    75.10.Dg
    Opis:
    Working in the strongly-correlated crystal-field approach and in the strong hybridization limit we calculated the temperature dependence of the heat capacity of NiO in a wide temperature range, from zero temperature to 1200 K. Our calculations reproduce reasonably well experimental dependence including the λ-type peak at $T_N$ of 525 K.
    Źródło:
    Acta Physica Polonica A; 2008, 114, 1; 213-217
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Proposed Experiment with Rydberg Atoms to Study the Influence of Particle Size on Quantum Interference
    Autorzy:
    Gondran, M.
    Božić, M.
    Arsenović, D.
    Gondran, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1814474.pdf
    Data publikacji:
    2007-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    03.75.Dg
    07.60.Ly
    03.65.Ta
    Opis:
    We are looking for the answers to some questions which naturally arise when one starts to think about possible influence of the size of a particle on the transmission, diffraction and interference pattern behind an interference grating.
    Źródło:
    Acta Physica Polonica A; 2007, 112, 5; 805-810
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Polimorfizmy w genach naprawy DNA – ocena częstości występowania i wpływ na poziom uszkodzeń oksydacyjnych w DNA indukowanych przez ołów
    Polymorphisms in DNA repair genes – assessment of frequencies and effect on the level of DNA oxidative damage caused by lead
    Autorzy:
    Olewińska, Elżbieta
    Kozłowska, Agnieszka
    Pawlas, Natalia
    Sieroń, Aleksander L.
    Powiązania:
    https://bibliotekanauki.pl/articles/1177657.pdf
    Data publikacji:
    2014
    Wydawca:
    Instytut Medycyny Wsi
    Tematy:
    8-OH-dG
    naprawa DNA
    ołów
    polimorfizmy genetyczne
    uszkodzenia DNA
    Opis:
    Introduction. The aim of this study was to evaluate the effect of polymorphisms in DNA repair genes: APE1, hOGG1, XRCC1, XPA on the level of oxidative damage to DNA as well as an assessment of the frequencies of genetic polymorphisms in the adult population of Caucasians from southern Poland. Material and methods. We examined a group of 115 men occupationally exposed to lead and 58 men with no history of occupational exposure to lead. The concentrations of lead in blood, zinc protoporphyrin in blood and 8-hydroxy-2-deoxyguanosine in urine were measured. The identification of SNP polymorphisms in genes encoding enzymes involved in DNA repair (APEX1, hOGG1, XPA, XRCC1) was performed using real-time PCR with TaqMan probes. We analyzed polymorphisms: APEX1 (rs1130409, Asp148Glu), hOGG1 (rs1052133, Ser326Cys), XPA (rs1800975, -4A/G) and XRCC1 (rs25487, Gln399Arg). Results. The mean blood lead level in the exposed group was 33,48 μg/dl and was significantly higher compared to 5.35 μg/dl (p=0.000). in the control group. The frequencies of studied polymorphisms were comparable in both groups, with the exception of -4A/G (rs1800975) in the gene XPA (p<0.0001). Conclusions. Differences were observed between genotypes in -4A/G (rs1800975) polymorphism in relations to the level of lead in blood (p=0.006) and Ser326Cys (rs1052133) polymorphism in relations to 8-hydroxy-2- deoxyguanosine in urine (p=0.01).
    Wstęp. Celem pracy była ocena wpływu polimorfizmów w genach naprawy DNA: APE1, hOGG1, XRCC1, XPA na poziom uszkodzeń oksydacyjnych w DNA oraz ocena częstości ich występowania w populacji dorosłych osób rasy kaukaskiej pochodzących z południowej Polski. Materiał i metody. Przebadano grupę 115 mężczyzn narażonych zawodowo na ołów oraz 58 mężczyzn bez narażenia na ołów w wywiadzie, którzy stanowili grupę kontrolną. U wszystkich osób oznaczono poziom ołowiu we krwi, cynkoprotoporfiryny, oraz stężenie 8-hydroksy- 2-deoksyguanozyny w moczu. Identyfikację polimorfizmów typu SNP w genach kodujących enzymy biorące udział w naprawie DNA (APEX1, hOGG1, XPA, XRCC1) przeprowadzono z wykorzystaniem metody real-time PCR z sondami TaqMan. Analizie poddano polimorfizmy w genach APEX1 (rs1130409, Asp148Glu), hOGG1 (rs1052133, Ser326Cys), XPA (rs1800975, -4A/G) oraz XRCC1 (rs25487, Gln399Arg). Wyniki. Średni poziom ołowiu we krwi w grupie badanej wynosił 33,48 μg/dl i był istotnie statystycznie wyższy niż w grupie kontrolnej, gdzie wynosił 5,35 μg/dl (p=0,000). Częstość występowania poszczególnych genotypów badanych polimorfizmów była porównywalna w obu grupach, z wyjątkiem polimorfizmu -4A/G (rs1800975) w genie XPA (p<0,0001). Wnioski. Zaobserwowano różnice pomiędzy poszczególnymi genotypami w polimorfizmie -4A/G (rs1800975) w odniesieniu do poziomu ołowiu we krwi (p=0,006) oraz w polimorfizmie Ser326Cys (rs1052133) w odniesieniu do poziomu 8-hydroksy-2-deoksyguanozyny w moczu (p=0,01).
    Źródło:
    Medycyna Środowiskowa - Environmental Medicine; 2014, 17, 4; 29-37
    1505-7054
    2084-6312
    Pojawia się w:
    Medycyna Środowiskowa - Environmental Medicine
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Simulations and measurements of eddy current magnetic signatures
    Badania pola magnetycznego od prądów wirowych indukowanych w kadłubie okrętu
    Autorzy:
    Polański, P.
    Szarkowski, F.
    Powiązania:
    https://bibliotekanauki.pl/articles/222220.pdf
    Data publikacji:
    2018
    Wydawca:
    Akademia Marynarki Wojennej. Wydział Dowodzenia i Operacji Morskich
    Tematy:
    ship’s magnetic signature
    eddy currents
    degaussing system (DG)
    physical scale model
    pole magnetyczne okrętu
    prądy wirowe
    system demagnetyzacji (OUD/DG)
    model fizyczny w skali
    Opis:
    Eddy current magnetic signature is, together with magnetization of ferromagnetic hull, mechanisms and devices on board, corrosion related and stray field sources one of the main sources of ship’s magnetic signature. Due to roll, pitch and yaw of the ship in external magnetic field, eddy currents are induced in conducting materials on board ship, mainly in conducting hull. Flow of those currents is a source of magnetic field around a ship. Principal eddy current component is related to roll movement as it depends on rate of change of external field which is the highest for roll. Induced currents have both in-phase and quadrature components. Magnitude of the eddy current magnetic field can have significant effect on total magnetic field signature after degaussing for ships such as mine sweepers and mine hunters. Paper presents calculations and simulations as well as measurements of model and physical scale model made of low magnetic steel performed in Maritime Technology Center. Contribution of eddy current magnetic field in total field in low roll frequencies has been estimated.
    Pole magnetyczne od prądów wirowych powstających w kadłubie jest jednym ze źródeł pola magnetycznego okrętu, obok pól od namagnesowania indukowanego i stałego obiektów ferromagnetycznych okrętu i znajdujących się na nim urządzeń związanych z procesami korozji i ochroną przed korozją (CRM) oraz pól rozproszeniowych. W wyniku przechyłów, przegłębień i zmian kursu okrętu w zewnętrznym polu geomagnetycznym indukowany jest przepływ prądu w przewodzącym kadłubie okrętu. Przepływ prądów wirowych jest źródłem pola magnetycznego w przestrzeni dookoła okrętu. Dominujące jest pole związane z przechyłami, gdyż zależy od częstotliwości zmian pola, która jest największa dla przechyłów. Prądy indukowane mają składową zgodną w fazie z przechyłami oraz przesuniętą o π/2. Wartości tego pola mogą mieć znaczący wpływ na sumaryczne pole magnetyczne po demagnetyzacji dla trałowców i niszczycieli min. W artykule przedstawiono obliczenia, symulacje oraz wyniki badań na modelach zastępczych oraz modelu fizycznym okrętu o konstrukcji kadłuba i nadbudówki wykonanych ze stali małomagnetycznej przewodzącej (austenitycznej) przeprowadzone w Centrum Techniki Morskiej (CTM). Oszacowano ilościowy udział pola od prądów wirowych w całkowitym polu magnetycznym okrętu dla bardzo niskich częstotliwości.
    Źródło:
    Zeszyty Naukowe Akademii Marynarki Wojennej; 2018, R. 59 nr 4 (215), 4 (215); 77-102
    0860-889X
    Pojawia się w:
    Zeszyty Naukowe Akademii Marynarki Wojennej
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influences of a "hybrid grid" on the networks voltage quality and supply reliability
    Autorzy:
    Bhattacharyya, S.
    Myrzik, J.
    Meeuwsen, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/262592.pdf
    Data publikacji:
    2007
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie
    Tematy:
    hybrid grid
    DG
    power system reliability
    voltage quality
    interruption
    NaS storage system
    Opis:
    The electricity is a basic need for functioning of modern society. In the deregulated electricity market, delivering quality power to the clients is a challenge for the utilities. In this paper, a "hybrid grid" is discussed that consists of centralized generations and localized distributed generations which may be comprised of small-scale conventional and sustainable sources. Energy storage option is also integrated in the hybrid-grid. Simulations are done on a test network, using "Power-Factory" software. It was found from the analysis that voltage quality and power supply availability of a hybrid-grid can be improved by proper selection of energy storage system along with protective and control devices.
    Źródło:
    Electrical Power Quality and Utilisation. Journal; 2007, 13, 2; 25-31
    1896-4672
    Pojawia się w:
    Electrical Power Quality and Utilisation. Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Conversions of the Second-Rank Zero Field Splitting Parameters Measured Assuming the Fictitious Spin S=1 to those for the Effective Spin S̃=2
    Autorzy:
    Kozanecki, M.
    Rudowicz, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/1030215.pdf
    Data publikacji:
    2017-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Ch
    75.10.Dg
    76.30.-v
    76.30.Fc
    Opis:
    We investigate feasibility of comparison between the zero field splitting parameters obtained experimentally based on the spin Hamiltonian with the fictitious spin S'=1 and those with the effective spin S̃=2. The former zero field splitting parameters have recently been measured for Fe²⁺ ions in forsterite Mg₂SiO₄, whereas the latter zero field splitting parameters are available in literature, e.g. for Fe²⁺ and Cr²⁺ (S̃=2) ions. It turns out that no unique direct comparison is feasible and hence appropriate conversion relations need to be derived. Methodology for such conversions is outlined. Various combinations of the possible energy level schemes for the spin S̃=2 and S'=1 are briefly described. Illustrative preliminary results concerning appropriate conversions of the second-rank zero field splitting parameters measured by high-frequency EMR for Fe²⁺ in natural and synthetic forsterite are presented. Detailed results and full analysis will be given elsewhere.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 1; 11-14
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Glass forming abilities and crystallization process in amorphous Pr-Fe-Co-Zr-Nb-B alloys of various B content
    Autorzy:
    Pawlik, K.
    Pawlik, P.
    Kaszuwara, W.
    Wysłocki, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1054842.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.dg
    61.05.cp
    75.20.En
    75.50.Vv
    Opis:
    The influence of boron contents on the glass forming abilities and magnetic properties of melt-spun ribbon samples produced from Pr₉Fe_{50+x}Co₁₃Zr₁Nb₄B_{23-x} (x=0, 2, 5, 8) alloys, were investigated. For all compositions, the rapidly solidified samples were fully amorphous, which was confirmed by X-ray diffractometry and the Mössbauer spectroscopy. Differential scanning calorimetry and differential thermal analysis studies revealed good glass forming abilities for all investigated specimens and allowed to determine thermal stability parameters of the amorphous phase. For all alloy ribbons, very large supercooled liquid region before crystallization ΔT_x reaching 100 K was measured. The Kissinger plots were constructed to determine the activation energies for crystallization. Annealing of specimens at temperatures ranging from 923 K to 1033 K for 5 min resulted in significant change of the phase constitution. The X-ray diffractometry studies have shown presence of hard magnetic Pr₂(Fe,Co)₁₄B and paramagnetic Pr_{1+x}Fe₄B₄ phases. Furthermore, with the increase of B contents in the alloy composition crystallization of α-Fe phase occurs at wider range of the annealing temperature. Anomaly of both thermal and magnetic properties was observed for the Pr₉Fe₅₂Co₁₃Zr₁Nb₄B₂₁ alloy ribbons.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 979-981
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental Investigation of Low Power Microwave Microplasma Source
    Autorzy:
    Czylkowski, D.
    Hrycak, B.
    Jasiński, M.
    Mizeraczyk, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1198978.pdf
    Data publikacji:
    2014-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    52.50.Dg
    52.70.Ds
    52.70.Kz
    52.80.Pi
    Opis:
    The aim of this paper is to present a novel microwave microplasma source generated in different gases at atmospheric pressure. The design, rule of operation and experimental investigations of the new microwave microplasma source are described. The main advantage of the presented microwave microplasma source is its small size, simplicity, and low cost of construction and operation. The microplasma has a form of a small plasma jet of dimensions of a few mm, depending on the kind of gas, gas flow rate, and absorbed microwave power. Presented in this paper results of experimental investigations were obtained with an atmospheric pressure argon, krypton, nitrogen, and air microplasma, sustained by microwaves of standard frequency of 2.45 GHz. The absorbed microwave power was up to 70 W. The gas flow rate was from 2 to 25 l/min. The miniature size, simplicity of the source and stability of the microplasma allow to conclude that the presented new microwave microplasma source can find practical applications in various fields.
    Źródło:
    Acta Physica Polonica A; 2014, 125, 6; 1323-1325
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Observation of Magnetic Anisotropy in GaN:Cr Single Crystals
    Autorzy:
    Gosk, J.
    Boćkowski, M.
    Kowalski, G.
    Grzegory, I.
    Szczytko, J.
    Twardowski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1403624.pdf
    Data publikacji:
    2012-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.55.Eq
    75.30.Gw
    75.50.Pp
    75.10.Dg
    Opis:
    Magnetic properties of bulk wurtzite GaN:Cr single crystals were studied with the magnetic field applied parallel and perpendicular to the crystal wurtzite c-axis. Structure of the crystal was examined by the X-ray diffraction method. Strong anisotropy of magnetization at low temperatures (2-10 K) was observed. The experimental data suggest Cr to be in nonspherical $d^4$ configuration.
    Źródło:
    Acta Physica Polonica A; 2012, 122, 6; 1007-1009
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimization of a Fabry-Perot Sensing Interferometer Design for an Optical Fiber Sensor of Hematocrit Level
    Autorzy:
    Wierzba, P.
    Jędrzejewska-Szczerska, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1399408.pdf
    Data publikacji:
    2013-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    07.60.Ly
    03.75.Dg
    42.81.Pa
    07.60.Vg
    Opis:
    Continuous measurement of the hematocrit level in blood can potentially be performed using optical fibre sensors. The Fabry-Perot interferometric sensors are a promising candidate in this application. The most important step in the design of the sensor is design of the sensing interferometer. Adequate cavity length and high interference contrast are two most important requirements in this application. The design method of the sensing interferometer presented in this paper uses a Gaussian beam approximation. In order to verify the design, an optical fibre Fabry-Perot interferometer with adjustable cavity length was built. Its performance was tested, confirming validity of the design approach.
    Źródło:
    Acta Physica Polonica A; 2013, 124, 3; 586-588
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    ESR Studies of Paramagnetic Centers in Pharmaceutical Materials - Cefaclor and Clarithromycin as an Example
    Autorzy:
    Skowronska, A.
    Wojciechowski, M.
    Ramos, P.
    Pilawa, B.
    Kruk, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/1490205.pdf
    Data publikacji:
    2012-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    87.15.La
    87.64.kj
    87.64.kh
    75.10.Dg
    Opis:
    Electron spin resonance (ESR) studies of two antibiotics, Cefaclor and Clarithromycin, have been performed in order to investigate concentration and dynamics of free radicals generated in these compounds due to thermal sterilization. For Cefaclor three combinations of temperature and heating time have been applied: 160°C, 170°C, 180°C for 120 min, 60 min, and 30 min, respectively, according to the pharmaceutical sterilization norm. Clarithromycin has been heated at 160°C for 120 min. The ESR lineshape has been investigated versus microwave power ranging from 2.2 mW to 70 mW. Electron spin-spin relaxation time has been estimated from the ESR lineshape analysis. Concentrations of radicals generated due to different sterilization procedures have been compared with the purpose to select the best sterilization scheme.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 2; 514-517
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Explanation of the Optical Spectra and Spin-Hamiltonian Parameters for Nickel(II) in Cadmium Bromide Crystal
    Autorzy:
    Gong, J.
    Wang, L.
    Feng, W.
    Yang, X.
    Zhang, F.
    Powiązania:
    https://bibliotekanauki.pl/articles/1493631.pdf
    Data publikacji:
    2011-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Ch
    75.10.Dg
    61.72.Bb
    76.30.Fc
    Opis:
    Based on crystal- and ligand-field theory, double-spin-orbital coupling approach was used to analyze the crystal-field energy levels and spin-Hamiltonian parameters of $Ni^{2+}$ ion at trigonal site in $CdBr_2$. The local lattice distortion (Δ R and $τ_{Ni^{2+}}$) is estimated from the crystal field parameters; the crystal field energy Hamiltonian was diagonalized in the full basis consisting of 45 wave functions of the $Ni^{2+}$ ion. Results of calculations are in good agreement with experimental data. The reasonableness of the theoretical results is discussed.
    Źródło:
    Acta Physica Polonica A; 2011, 120, 3; 497-500
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spin-Spin and Spin-Other-Orbit Interactions of Spin-Hamiltonian Parameters for $3d^{2(8)}$ Ions in $Al_2O_3$ Crystals
    Autorzy:
    Wei, Q.
    Guo, L.
    Yang, Z.
    Wei, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1505102.pdf
    Data publikacji:
    2011-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.Fc
    71.70.Ch
    75.10.Dg
    71.55.Ht
    Opis:
    By considering weaker magnetic interactions (including spin-spin and spin-other-orbit interactions) in Hamiltonian, the spin-Hamiltonian parameters, including the zero-field splitting parameter D and g factors $(g_∥, g_⊥)$ for $3d^{2(8)}$ ions in $Al_2O_3$ crystals have been investigated. The results show that the contributions to D, $g_∥$ and $g_⊥$ from the spin-orbit interaction are dominant. The contributions from weaker magnetic interactions to D decrease (increase) with increasing charge of impurity ions for $3d^2 (3d^8)$ ions.
    Źródło:
    Acta Physica Polonica A; 2011, 119, 6; 857-859
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Implications of Invalid Conversions between Crystal-Field Parameters and Zero-Field Splitting Ones Used in Superposition Model
    Autorzy:
    Rudowicz, C.
    Karbowiak, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1365340.pdf
    Data publikacji:
    2014-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.-v
    76.30.Fc
    71.70.Ch
    75.10.Dg
    Opis:
    The methodology used in recent study of the zero-field splitting parameters of $Cr^{3+}$ ions at various orthorhombic symmetry sites in $LiKSO_4$ by Pandey and Kripal is critically commented on. We argue that the crystal field parameters, $B_{kq}$, in the Wybourne notation, which were calculated using the superposition model for $Cr^{3+}$ ions in $LiKSO_4$, may only be converted into the crystal field parameters in the Stevens notation. Regrettably, the authors have also converted the latter parameters supposedly into the zero-field splitting parameters D and E in the conventional notation. Such direct conversions are fundamentally incorrect and constitute factual invalid usage of the conversion relations between the crystal field (ligand field) parameters and the zero-field splitting ones. The cases of an implied usage of the invalid conversion relations between the crystal field parameters and the zero-field splitting parameters occurring in recent literature are also outlined. Pandey and Kripal have found the zero-field splitting parameters theoretically evaluated in this way to be in good agreement with the experimental values. However, the faulty methodology renders the conclusion that $Cr^{3+}$ ions enter into the $LiKSO_4$ lattice at the substitutional $K^{+}$ sites unjustified. Several other conceptual problems arising from misinterpretations of the crucial notions identified therein are also discussed and clarified.
    Źródło:
    Acta Physica Polonica A; 2014, 125, 5; 1215-1219
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Real time voltage stabilization in microgrid
    Autorzy:
    Jangjoo, M. A.
    Seifi, A. R.
    Powiązania:
    https://bibliotekanauki.pl/articles/141091.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    capacitor
    distributed generation (DG)
    on load tap changer (OLTC)
    voltage stabilization
    microgrid
    Opis:
    This study suggests a new algorithm based on a combination of fuzzy logic and genetic algorithm (GA) to improve voltage profile in a microgrid. The considered microgrid includes control variables such as onload tap changer (OLTC), active power output from distributed generators (DG) and reactive power output from feeder switched capacitors that are controlled in a microgrid controller (MGC) by communication links. The proposed method was used to obtain the optimum value of control variables to establish voltage stabilization in varying load condition as online. For establishing voltage stabilization at the microgrid, an objective function is defined and is tried to minimize it by control variables. The control variables were changed based on fuzzy logic and the GA was employed for finding the optimum shape of membership functions. In order to verify the proposed method, a 34 buses microgrid in varying load condition was analyzed and was compared with previous works.
    Źródło:
    Archives of Electrical Engineering; 2014, 63, 2; 273-293
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Renormalization group calculation of dynamic exponent in the models E and F with hydrodynamic fluctuations
    Autorzy:
    Dančo, M.
    Hnatič, M.
    Komarova, M.
    Lučivjanský, T.
    Nalimov, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1054851.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.60.ae
    64.60.Ht
    67.25.dg
    47.27.Jv
    Opis:
    The renormalization group method is applied in order to analyze models E and F of critical dynamics in the presence of velocity fluctuations generated by the stochastic Navier-Stokes equation. Results are given to the one-loop approximation for the anomalous dimension γ_{λ} and fixed-points' structure. The dynamic exponent z is calculated in the turbulent regime and stability of the fixed points for the standard model E is discussed.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 651-653
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Crystal structure and EPR investigation of pyrazinamide containing copper (II) 2-nitrobenzoate single crystal
    Autorzy:
    Çelik, Y.
    Bozkurt, E.
    Karabulut, B.
    Dege, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/1070369.pdf
    Data publikacji:
    2016-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.05.cp
    75.10.Dg
    76.30.-v
    78.30.-j
    Opis:
    The crystal structure and paramagnetism in the pyrazinamide containing copper(II) 2-nitrobenzoate single crystal were investigated using X-ray diffraction, Fourier-transform infrared spectroscopy, and electron paramagnetic resonance techniques. X-ray diffraction analysis shows that the complex crystallizes in monoclinic system having two molecules in the unit cell. After using curve fitting method to the electron paramagnetic resonance spectra, anisotropic g and hyperfine A tensors were obtained. The local symmetry, spin Hamiltonian parameters, and molecular bonding coefficients of the paramagnetic Cu²⁺ ion were determined. Perturbation approach was applied to the spin Hamiltonian to calculate the g and A values.
    Źródło:
    Acta Physica Polonica A; 2016, 130, 1; 163-166
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Properties of $La_3Ga_{5.5}Ta_{0.5}O_{14}$ Single Crystals Doped with Sm³⁺ and Er³⁺ Ions
    Autorzy:
    Kaczmarek, S.
    Leniec, G.
    Berkowski, M.
    Kazan, S.
    Acikgoz, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1398323.pdf
    Data publikacji:
    2017-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    76.30.Kg
    75.30.Gw
    75.40.Cx
    Opis:
    Electron paramagnetic resonance and magnetic susceptibility measurements were performed for two $La_3Ga_{5.5}Ta_{0.5}O_{14}$ single crystals doped with 1.96 at.% of Sm³⁺ ions and 3.8 at.% of Er³⁺ ions. Two magnetically inequivalent sites were found to be responsible for the electron paramagnetic resonance spectra of Sm³⁺ ions. Both sites reveal a low (at least C₂) symmetry with $g_{x}$~0.46, $g_{y}$~0.46 and $g_{z}$~0.52. The symmetry of isolated erbium ions is higher than C₂. From electron paramagnetic resonance and magnetic susceptibility experiments it results that the ground state of Er³⁺ ions is Γ⁶ or Γ⁷. Below 51 K electronic transitions within Γ⁶ doublets take place. Between 51 and 60 K, Γ⁶ to Γ⁷ transitions dominate, while above 60 K mainly transitions within Γ⁷ doublet are active.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 3; 366-369
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Complete Diagonalization Calculation of the Optical and EPR Data for the Tetragonal $Cu^{2+}$ Center in $Cu^{2+}$-Doped ZnSe Nanocrystals
    Autorzy:
    Wu, Xiao-Xuan
    Zheng, Wen-Chen
    Powiązania:
    https://bibliotekanauki.pl/articles/1399131.pdf
    Data publikacji:
    2015-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.Fc
    71.70.Ch
    78.40.Fy
    75.10.Dg
    Opis:
    By using the complete diagonalization (of energy matrix) method based on the cluster approach (where the admixture between the d orbitals of $d^{n}$ ion and p orbitals of ligands due to covalence effect is considered), the optical and electron paramagnetic resonance data (three optical band positions and four EPR parameters $g_{∥}$, $g_{⊥}$, $A_{∥}$, $A_{⊥}$) are calculated for the tetragonal $Cu^{2+}$ center in $Cu^{2+}$-doped poly vinyl alcohol (PVA) passivated ZnSe nanocrystals with the defect model of $Cu^{2+}$ in the interstitial octahedral site in ZnSe. The calculated results are near the experimental values. The tetragonal elongation of the $Cu^{2+}$ octahedral cluster in ZnSe nanocrystals is obtained. The results are discussed.
    Źródło:
    Acta Physica Polonica A; 2015, 127, 3; 795-798
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    NMR Relaxation and ESR Lineshape of Anisotropically Rotating Paramagnetic Molecules
    Autorzy:
    Kubica, A.
    Milewska, A.
    Noinska, M.
    Earle, K.
    Kruk, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/1490224.pdf
    Data publikacji:
    2012-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    87.64.kj
    87.64.kh
    75.10.Dg
    76.60.Es
    Opis:
    The role of anisotropic rotation for electron spin resonance lineshape and nuclear magnetic relaxation dispersion profiles for paramagnetic molecules with electron spin quantum number S ≥ 1 is discussed. The ESR spectra and nuclear magnetic relaxation dispersion profiles are calculated by means of an approach based on the stochastic Liouville equation and referred to in the literature as "Swedish slow motion theory". This description is valid for arbitrary motional conditions and interaction strengths. Molecular tumbling influences the ESR spectra by modulating zero field splitting interactions. The nuclear spin relaxation is affected by the rotational motion in a twofold way: via the electron spin dynamics and as a direct source of modulations of the electron-nuclear dipole-dipole interactions. For coinciding principal axes systems of the permanent (residual, static) zero field splitting and rotational tensors the ESR lineshape is not affected by rotational anisotropy. Rotational anisotropy is important for nuclear relaxation as it is influenced by molecular rotation not only via the electron spin dynamics, but also directly by modulations of the electron spin-nuclear spin dipole-dipole interaction (when the dipole-dipole and zero field splitting frames do not coincide). The anisotropy effects depend strongly on the relative orientation of the dipole-dipole and permanent zero field splitting axes. Nevertheless, a different scenario is also possible. When the diffusion axis coincides with the dipole-dipole axis (but not with the principal axis system of the permanent zero field splitting), the nuclear spin relaxation as well as the ESR lineshape, become sensitive to the rotational anisotropy. The possible dependence of the ESR lineshape and nuclear spin relaxation on the rotational anisotropy should be carefully considered when attempting a joint analysis of ESR and nuclear magnetic relaxation dispersion results for paramagnetic molecules.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 2; 527-532
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Full Susceptibility Tensor for Localized Spin Models with S = 1, 3/2, 2, 5/2 and with Rhombic Anisotropy
    Autorzy:
    Pełka, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1505395.pdf
    Data publikacji:
    2011-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    75.10.Jm
    75.30.Gw
    75.50.Xx
    Opis:
    A general discussion of the simulation procedure of the full susceptibility tensor and isothermal magnetization pseudovector for compounds comprising weakly-interacting magnetic centers is presented. A single-crystal-sample as well as a powder-sample case are considered. The procedure is used to obtain explicit expressions for the full susceptibility tensor for spins S = 1, 3/2, 2, and 5/2 for non-vanishing rhombic local anisotropy and any form of spectroscopic tensor.
    Źródło:
    Acta Physica Polonica A; 2011, 119, 3; 428-436
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of Ball Milling on the Local Atomic Structure of an Amorphous CoFeSiB Alloy
    Autorzy:
    Bednarcik, J.
    Michalik, S.
    Kollar, P.
    Roth, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1534068.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.43.Dq
    61.05.cp
    64.70.dg
    75.30.Kz
    Opis:
    It follows from experimental observations that ball milling induces substantial changes in an amorphous $Co_{70.3}Fe_{4.7}Si_{10}B_{15}$ (at.%) alloy. X-ray diffraction indicates formation of nanocrystalline bcc-(Co,Fe) phase during ball milling. As a consequence crystallization sequence is altered and the total enthalpy of crystallization reduces with the milling time. Furthermore thermomagnetic measurements reveal that specific magnetization and Curie temperature of amorphous phase are influenced by ball milling.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 825-826
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Theoretical Studies of ESR Parameters and Local Lattice Structure of the Vanadate-Lithium-Borate Glasses
    Autorzy:
    Feng, W.
    Zhao, M.
    Li, T.
    Zhang, X.
    Xue, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1419845.pdf
    Data publikacji:
    2012-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Ch
    75.10.Dg
    61.72.Bb
    76.30.Fc
    Opis:
    Electron spin resonance spectral parameters of $V^{4+}$ ions in vanadate-lithium-borate glasses have been calculated by the crystal-field theory. The theoretical results are $g_{∥ }$ = 1.940, $g_{⊥}$ = 1.983 and $A_{∥ } = -175 \times 10^{-4} cm^{-1},$ $A_{⊥} = -65 \times 10^{-4} cm^{-1}$ which are good agreement with the experimental values ($g_{∥ }$ = 1.939(3), $g_{⊥}$ = 1.998(3) and $A_{∥ } = (170.6-176.4) \times 10^{-4} cm^{-1},$ $A_{⊥} = (61.3-71.4) \times 10^{-4} cm^{-1}$). In addition, the bond lengths of the local lattice structure are, respectively, $R_{∥ }$ = 1.5 Å and $R_{⊥}$ = 1.95 Å which have been shown to have a compressed tetrahedral geometry along the $C_4$ axis.
    Źródło:
    Acta Physica Polonica A; 2012, 122, 1; 167-169
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Theoretical Explanations of the Optical Band Positions and Local Structure for $Cu^{2+}$ Centers in $ZnO-Bi_{2}O_{3}-B_{2}O_{3}-CuO$ Glasses
    Autorzy:
    Yuan, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1377767.pdf
    Data publikacji:
    2014-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.72.Bb
    75.10.Dg
    76.30.-v
    76.30.Fc
    Opis:
    The local structure, two optical band positions and three electronic spin resonance parameters for $Cu^{2+}$ centers at the tetragonally-distorted octahedral sites in $ZnO-Bi_2O_3-B_2O_3-CuO$ glasses are calculated from the high-order perturbation method based on the two-spin-orbit-parameter model, where the contributions from both the spin-orbit coupling parameters of central $d^{n}$ ion and ligand ion are included. The theoretical results are in good agreement with the experimental values. The calculations show that the high-order perturbation method based on the two-spin-orbit-parameter model is effective in the explanations of optical spectra, electronic spin resonance parameters and local distortion structure for $d^{9}$ ions in glasses.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 6; 1293-1295
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Low-Symmetry Aspects in EPR Spectra of Mn$\text{}^{2+}$ at Bi$\text{}^{3+}$ Sites in BiVO$\text{}_{4}$ Single Crystal
    Autorzy:
    Yeom, T. H.
    Choh, S. H.
    Rudowicz, Cz.
    Powiązania:
    https://bibliotekanauki.pl/articles/1920948.pdf
    Data publikacji:
    1992-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    76.30.Da
    61.16.Hn
    78.20.Hp
    Opis:
    Zero-field splitting parameters obtained from EPR X-band experiments of Baran et al. (1985) and Yeom et al. (1992) are reanalyzed. Transformation relations are derived to express the two sets of data in the same axis system. Problems arising from using a truncated zero-field splitting Hamiltonian in fitting the experimental data are elucidated. Low-symmetry aspects in EPR spectra of Mn$\text{}^{2+}$ at Bi$\text{}^{3+}$ sites in BiVO$\text{}_{4}$ single crystal are considered. Good agreement for orthorhombic parameters b$\text{}_{2}^{0}$ and b$\text{}_{2}^{2}$ is obtained indicating that the centres observed in the two cases are the same Mn centres. The remaining b$\text{}_{k}^{q}$ parameters accounting for the actual site symmetry around Mn$\text{}^{2+}$ impurity which seems to be lower than orthorhombic in the ferroelastic phase cannot be unambiguously determined from the existing EPR data.
    Źródło:
    Acta Physica Polonica A; 1992, 82, 3; 503-510
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Symmetry Induced Half-Metallic Alkaline Earth Ferromagnets
    Autorzy:
    Adamowicz, L.
    Wierzbicki, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1810473.pdf
    Data publikacji:
    2009-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.15.Mb
    71.20.Dg
    72.25.Ba
    75.10.Lp
    Opis:
    Search for new half-metallic ferromagnetic binary compounds composed of alkaline earth and III (boron) or IV (carbon) elements is reported. Ab initio all-electron density functional theory calculations in the generalised gradient approximation indicate possibility of half-metallic ferromagnetism. This is a new class of theoretically predicted hypothetical materials, without transition metal elements, not as yet discovered experimentally. Ferromagnetism is expected to be induced by suitable crystalline structure with lattice constant above some critical value. The predominant p electrons mechanism seems to be responsible for the formation and interactions of localised magnetic moments on boron or carbon atoms.
    Źródło:
    Acta Physica Polonica A; 2009, 115, 1; 217-219
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spectroscopic Study of $CO_2$ Plasma in Microwave Source Designed for Hydrogen Production via Hydrocarbons Decomposition
    Autorzy:
    Hrycak, B.
    Jasiński, M.
    Mizeraczyk, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1366177.pdf
    Data publikacji:
    2014-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    52.25.Os
    52.50.Dg
    52.70.Kz
    52.80.Pi
    Opis:
    In this paper, results of spectroscopic study of microwave (2.45 GHz) plasma at atmospheric pressure and high $CO_2$ flow rate are presented. The plasma was generated by waveguide-supplied nozzleless cylindrical type microwave plasma source. Working gas flow rate and microwave absorbed power varied from 50 up to 150 l/min and from 1 up to 5.5 kW, respectively. The emission spectra in the range of 300-600 nm were recorded. The rotational and vibrational temperatures of $C_2$ molecules, as well as the rotational temperature of OH radicals were determined by comparing the measured and simulated spectra. The plasma gas temperature inferred from rotational temperature of heavy species ranged from 4000 to 6000 K. It depended on location in plasma, microwave absorbed power and working gas flow rate. The presented microwave plasma source can be used in various gas processing applications.
    Źródło:
    Acta Physica Polonica A; 2014, 125, 6; 1326-1328
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigations of the Optical Band Positions and Spin-Hamiltonian Parameters for the Rhombic $VO^{2+}$ Complex in CsCl Crystal
    Autorzy:
    Fang, W.
    Zheng, W.
    Yang, D.
    Tang, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1365269.pdf
    Data publikacji:
    2014-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Ch
    75.10.Dg
    61.72.Bb
    76.30.Fc
    Opis:
    The optical band positions and spin-Hamiltonian parameters (g factors $g_{i}$ and hyperfine structure constants $A_{i}$, where i=x, y, z) of the rhombic $VO^{2+}$ complex in CsCl crystal are calculated together from two theoretical methods. One is the complete diagonalization (of energy matrix) method and another is the perturbation theory method. The calculated results from the two methods coincide and are in reasonable agreement with the experimental values. So, both methods are effective in the explanations of optical and electron paramagnetic resonance (EPR) data for $d^1$ ions in crystals. The calculations also suggest that in $d^1$ rhombic octahedra the ground state is almost a pure | $d_{xy}$ ⟩ state. This point is different from that of conjugate $d^9$ (e.g., $Cu^{2+}$) ions in rhombic octahedra where the ground state should be an admixture of ground and first excited states.
    Źródło:
    Acta Physica Polonica A; 2014, 125, 5; 1206-1209
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Neural network-based allocation and self-improved firefly-based optimal sizing of fuel cells in distributed generation systems
    Autorzy:
    Subramanyam, T. C.
    Tulasi Ram, S. S.
    Subrahmanyam, J. B. V.
    Powiązania:
    https://bibliotekanauki.pl/articles/1839111.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    DG system
    fuel cells
    location
    sizing
    multiple objectives
    firefly algorithm
    self-improved firefly algorithm
    Opis:
    The notion of Distributed Generation (DG) refers to the production of power at the level of consumption. Production of energy on-site, instead of offering it centrally, reduces the cost, internal dependencies, difficulties, inefficiencies, and risks that are related to transmission and distribution systems. In case DG is realized with fuel cells, several issues exist in respect to allocating and sizing of these fuel cells in the system. For solving those issues, dual stage intelligent technique is employed in this paper. First, the Neural Networks (NN) technique is adopted for determining the required location to place the fuel cells. Secondly, an enhanced version of Self Improved Fire-Fly (SIFF) algorithm is adopted for finding the optimal size of the fuel cells. The implemented technique is simulated in four IEEE benchmark test bus systems, and the respective performance analysis along with statistical analysis serves for validation purposes. The here proposed technique is compared with six other known algorithms, namely Particle Swarm Optimization (PSO), Firefly (FF) algorithm, Artificial Bee colony (ABC) algorithm, Improved Artificial Bee colony algorithm (IABC), Genetic Algorithm (GA) and Global Search Optimizer (GSO). The results obtained from the comparative analysis show the enhanced performance of the proposed mechanism.
    Źródło:
    Control and Cybernetics; 2018, 47, 4; 357-381
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Neutronic analysis of LBE-uranium spallation target accelerator driven system loaded with uranium dioxide in TRISO particles
    Autorzy:
    Bakir, G.
    Selçuklu, S.
    Genç, G.
    Yapici, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1068556.pdf
    Data publikacji:
    2016-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    28.20.-v
    28.20.Np
    28.65.+a
    29.20.dg
    29.85.Fj
    Opis:
    This study presents the neutronic performances of fissile breeding and energy production of a gas cooled accelerator-driven system with LBE-uranium dioxide (UO₂) spallation target. The accelerator-driven system is designed and optimized by considering various target materials, in terms of neutronic. Two different materials, LBE + natural UO₂ and LBE + 15% enrichment UO₂ are selected as target materials. The target zone is divided into two parts, one within the other; the outer part is pure LBE target part, and the inner part is UO₂ target part cooled with the helium gas. Tristructural-isotropic (TRISO)-coated fuel particles, containing UO₂ fuel, are embedded in a carbon matrix pebble with the packing fraction of a 29%, and the pebbles are placed in the UO₂ target part and in the fuel core with the packing fraction of a 60%. The fuel core is cooled with helium that is a high-temperature coolant. The target is bombarded with the continuous beams of a 1 GeV protons to produce high-flux neutrons that enter the fuel core. The fuel core is surrounded with a graphite reflector zone serving as both effective moderation and reflection of these neutrons. Furthermore, the whole system is enclosed by boron carbide, B₄C (shielding zone), to prevent the neutrons leakage out of the accelerator-driven system. The high-energy Monte Carlo code MCNPX along with the LA150 library is used for neutronic calculations. The numerical results bring out that the investigated accelerator-driven system has a high neutronic performance, from the energy production and fissile breeding points of view. Namely, it can be obtained over the thermal power of a 350 MW and produced over the fissile breeding of a 300 g/day.
    Źródło:
    Acta Physica Polonica A; 2016, 130, 1; 30-32
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study of Glass Transition and Crystallization Behavior in $Ga_{15}Se_{85 - x}Pb_x$ (0 ≤ x ≤ 6) Chalcogenide Glasses
    Autorzy:
    Khan, Z.
    Khan, S.
    Alvi, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1400308.pdf
    Data publikacji:
    2013-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.43.Dq
    61.05.cp
    64.70.p
    64.70.dg
    65.60.+a
    Opis:
    There has been a growing interest in the synthesis and characterization of amorphous chalcogenide glasses due to their importance in preparing electronic memories, grating, switching devices and their optical applications as good IR transmitting materials. The study of the glass transformations and crystallization processes in the amorphous systems is interesting not only from the fundamental aspect of establishing the reaction mechanism of crystal nucleation and growth, but also from a technological point of view. The present research work is concentrated on the study of glass transition and crystallization behavior in $Ga_{15}Se_{85 - x}Pb_x$ with x=0, 3, and 6 chalcogenide glasses by differential scanning calorimetry. Their amorphous nature has been verified by X-ray diffraction. The differential scanning calorimetry experiments were performed at different continuous heating rates (5 to 25 K/min). The glass transition temperature (T_{g}) and crystallization temperature $(T_{c})$ of these glasses has been determined from differential scanning calorimetry thermograms. The dependence of $T_{g}$ and $T_{c}$ on the heating rate (β) has been used for the determination of different crystallization parameters such as the activation energy of crystallization (Δ $E_{c}$), the activation energy for structural relaxation (Δ $E_{t}$) and the order parameter (n). The results of crystallization were discussed on the basis of different models such as Kissinger's approach and modification for non-isothermal crystallization in addition to Johnson, Mehl, Ozawa and Avrami.
    Źródło:
    Acta Physica Polonica A; 2013, 123, 1; 80-86
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nanometer-Scale Incoherent Imaging Using Laser-Plasma EUV Source
    Autorzy:
    Wachulak, P.
    Bartnik, A.
    Fiedorowicz, H.
    Kostecki, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1490098.pdf
    Data publikacji:
    2012-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    52.38.Ph
    52.50.Dg
    41.50.+h
    42.30.Va
    42.79.Ci
    Opis:
    Various imaging methods and techniques capable of reaching a nanometer spatial resolution are currently under development. One of them is an extreme ultraviolet microscopy, based on the Fresnel zone plates. In this paper a compact, high-repetition, laser-plasma EUV source, with a gas puff target, capable of emitting quasi-monochromatic radiation at 13.8 nm wavelength was used in the first demonstration of a desk-top EUV transmission microscopy with a spatial (half-pitch) resolution of 50 nm. EUV microscopy images of objects with various thicknesses and the spatial resolution measurements using the knife-edge test are presented.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 2; 450-453
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Direct Simulations of the Quantum Model for CsNiF$\text{}_{3}$
    Autorzy:
    Caramico D'Auria, A.
    Esposito, F.
    Esposito, U.
    Kamieniarz, G.
    Dekeyser, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1930597.pdf
    Data publikacji:
    1994-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.60.Cn
    75.10.Dg
    75.10.Jm
    75.40.Cx
    75.40.Mg
    Opis:
    We address the problem of reliability of a finite-chain technique for CsNiF$\text{}_{3}$. We investigate the effect of the boundary conditions, completely neglected so far, and apply a new extrapolation procedure appropriate for quantities showing non-monotonic behaviour. From a detailed analysis of the specific heat existing theoretical estimates for the model parameters are discriminated and a strong evidence for the reliability of the direct finite-chain technique predictions is presented.
    Źródło:
    Acta Physica Polonica A; 1994, 85, 2; 409-412
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Cr-Based II-VI Semimagnetic Semiconductors
    Autorzy:
    Twardowski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1931875.pdf
    Data publikacji:
    1995-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    75.30.Gw
    75.50.Pp
    75.20.Hr
    78.30.Fs
    Opis:
    We review the magnetic and optical properties of recently grown Cr-based II-VI semimagnetic semiconductors. We focus on two features of these materials which distinguish them from other semimagnetic semiconductors: the particular magnetic behaviour of these crystals, resulting from the Cr$\text{}^{++}$ ion energy structure determined by a strong, static Jahn-Teller effect, and a ferromagnetic p-d exchange interaction, which is unique for II-VI semimagnetic semiconductors.
    Źródło:
    Acta Physica Polonica A; 1995, 87, 1; 85-93
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Microbial Inactivation by Electric Discharge with Metallic Grid
    Autorzy:
    Scholtz, V.
    Kvasničková, E.
    Julák, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1399503.pdf
    Data publikacji:
    2013-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    52.50.Dg
    52.75.-d
    52.80.Hc
    52.80.-s
    87.19.xb
    Opis:
    The area of microbial inactivation by the low-temperature plasma produced by DC electric cometary discharge is increased by insertion of an electrically insulated metallic grid between the discharge and the target object. Gram-negative bacteria are almost fully inactivated; an additional zone of incomplete inactivation appears for Gram-positive bacteria and yeasts.
    Źródło:
    Acta Physica Polonica A; 2013, 124, 1; 62-65
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Reconstruction of the Exchange Integrals Map of ScFe₄Al₈ Magnetic Structure
    Autorzy:
    Rećko, K.
    Dobrzyński, L.
    Waliszewski, J.
    Szymański, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/1386376.pdf
    Data publikacji:
    2015-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.05.fm
    71.20.Be
    71.70.Gm
    75.10.Dg
    75.30.Et
    Opis:
    The influence of the dipolar as well as crystal field interaction as the main reasons of the noncollinearity and incommensurability of the 3d-3d-3p alloy belonging to ThMn₁₂ family is investigated. Available data on the single crystal neutron scattering experiments for ScFe₄Al₈ compound are discussed. The values and directions of the spin ordering found by magnetic diffraction are compared to that one derived from ground state configurations obtained by a simulated annealing algorithm.
    Źródło:
    Acta Physica Polonica A; 2015, 127, 2; 424-426
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Coherent Beam Splitting by a Thin Grating
    Autorzy:
    Božić, M.
    Dimić, D.
    Davidović, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1791193.pdf
    Data publikacji:
    2009-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    03.75.-b
    03.75.Be
    03.75.Dg
    42.25.Fx
    42.25.Hz
    Opis:
    The wide use of beam splitters in quantum interferometry, attosecond metrology, modern quantum information processing, foundations of quantum mechanics, has been based on coherence of beams emerging from a beam splitter. Here we further develop the approach in which a beam splitter is regarded as a transformer of an incident wave field (photon field or matter wave field) into a field which has narrow maxima at the points along and in close vicinity of two or more particular lines. This description was derived by considering a thin grating as a model of a beam splitter for photons, atoms and molecules. It is applied to answer some questions raised in the discussions on the interpretation of wave particle duality.
    Źródło:
    Acta Physica Polonica A; 2009, 116, 4; 479-482
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Technical and Economical Evaluation of Proton Exchange Merobrane (PEM) Fuel Cell for Commercial Applications
    Autorzy:
    Katyara, S.
    Iżykowski, J
    Staszewski, Ł
    Shaikh, F.
    Powiązania:
    https://bibliotekanauki.pl/articles/410535.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    Proton Exchange Membrane
    PEM
    Fuel Cell
    DC/DC boost converter
    Distributed Generation
    DG
    polarization curve
    efficiency
    Opis:
    The green energy sources are the utmost needs of today’s world where the reserves of fossil fuel are depleting day by day. The Distributed Generation (DG) has become integral part of power system at commercial level. The most efficient among all DGs and Renewable Energy Sources (RES) is the Fuel Cell (FC) power generation. The fuel cell invariably converts chemical energy directly into electricity. The Fuel cells have normally 60 to 70% efficiency at working conditions. The polarization curve of fuel cell plays important role in improving its efficiency. This research presents the mathematical and Simulink modeling 6 kW, 45 Vdc of Proton Exchange Membrane (PEM) fuel cell. The input thermodynamic parameters of fuel cell are varied and their effects on the output electrical variable are observed. The DC/DC boost converter is used to step up the voltage of fuel cell to 100 Vdc at commercial usable level. A new mathematical equation is presented to improve the efficiency of fuel. The mathematical results are then varied through Simulink results.
    Źródło:
    Present Problems of Power System Control; 2017, 8; 41-49
    2084-2201
    Pojawia się w:
    Present Problems of Power System Control
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Area equivalent WKB Compact modeling approach for tunneling probability in Hetero-Junction TFETs including ambipolar behaviour
    Autorzy:
    Horst, Fabian
    Farokhnejad, Atieh
    Darbandy, Ghader
    Iñíguez, Benjamín
    Kloes, Alexander
    Powiązania:
    https://bibliotekanauki.pl/articles/397787.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Łódzka. Wydział Mikroelektroniki i Informatyki
    Tematy:
    TFET
    tunneling probability
    WKB approximation
    heterojunction
    compact modeling
    closed-form
    double-gate
    DG
    ambipolarity
    modelowanie kompaktowe
    dwubiegunowość
    Opis:
    This paper introduces an innovative modeling approach for calculating the band-to-band (B2B) tunneling probability in tunnel-field effect transistors (TFETs). The field of application is the usage in TFET compact models. Looking at a tunneling process in TFETs, carriers try to tunnel through an energy barrier which is defined by the device band diagram. The tunneling energy barrier is approximated by an approach which assumes an area equivalent (AE) triangular shaped energy profile. The simplified energy triangle is suitable to be used in the Wentzel-Kramers-Brillouin (WKB) approximation. Referring to the area instead of the electric field at individual points is shown to be a more robust approach in terms of numerical stability. The derived AE approach is implemented in an existing compact model for double-gate (DG) TFETs. In order to verify and show the numerical stability of this approach, modeling results are compared to TCAD Sentaurus simulation data for various sets of device parameters, whereby the simulations include both ON- and AMBIPOLAR-state of the TFET. In addition to the various device dimensions, the source material is also changed to demonstrate the feasibility of simulating hetero-junctions. Comparing the modeling approach with TCAD data shows a good match. Apart the limitations demonstrated and discussed in this paper, the main advantage of the AE approach is the simplicity and a better fit to TCAD data in comparison to the quasi-2D WKB approach.
    Źródło:
    International Journal of Microelectronics and Computer Science; 2018, 9, 2; 47-59
    2080-8755
    2353-9607
    Pojawia się w:
    International Journal of Microelectronics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Development of Composites with Icosahedral Phase in Al-Cu-Fe Quasicrystalline Alloys Obtained by the Bridgman Method
    Autorzy:
    Krawczyk, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1373217.pdf
    Data publikacji:
    2014-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.05.Bx
    81.10.Fq
    64.70.dg
    61.72.-y
    61.44.Br
    68.37.Hk
    Opis:
    The composites were obtained by the Bridgman method through solidification of $Al_{61}Cu_{27}Fe_{12}$ alloy (numbers indicate at.%). The microstructure of composites with crystal matrix and quasicrystal reinforcement was studied. The crystalline β-phase was the matrix and the quasicrystaline i-phase was the reinforcement of obtained composites. The shape and spatial distribution of reinforcement fibres were specified. Some geometrical relations of the fibres arrangement were defined. Obtained composite samples were subjected to X-ray phase analysis, optical, and scanning electron microscopy observations, chemical microanalysis and the Laue diffraction.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 2; 501-504
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Novel Modulator Topology for Corona Plasma Generation
    Autorzy:
    Ariaans, T.
    Pemen, A.
    Winands, G.
    Liu, Z.
    van Heesch, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/1807899.pdf
    Data publikacji:
    2009-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    52.50.Dg
    52.70.Ds
    52.70.Kz
    52.80.Hc
    82.33.Xj
    96.60.pf
    Opis:
    Gas cleaning using plasma technology is slowly introduced into industry nowadays. Several challenges still have to be overcome: increasing the scale, safety, life-time and reducing costs. In 2006 we demonstrated a 20 kW nanosecond pulsed corona system. The electrical efficiency was > 90%. O-radical yields were found to be very high (3-7 mole/kWh). However, to be competitive, high costs of the pulsed power technology are still a major hurdle. Here we present a novel modulator for efficient generation of large volume corona plasma. Only a small amount of expensive high-voltage components are required. Switching is done at an intermediate voltage level of 1 kV with standard thyristors. At the high-voltage side, only a diode and a pulse transformer are needed. The estimated costs are about 5 kEuro/kW, whereas for state-of-the-art pulsed power technology these costs usually are about 20-30 kEuro/kW. Detailed investigations on the modulator and a wire-plate corona reactor will be presented. Modulator parameters have been varied systematically as well as reactor parameters (number of electrodes, electrode-plate distance). The O-radical yield was determined from the measured ozone concentrations at the exhaust of the reactor. With a detailed kinetic model, ozone concentrations could be calculated back to the initial O*-yields. The following conclusions will be discussed: for all parameters, an electrical efficiency of > 90% could be obtained. With fast imaging, the average streamer width was found to be ∼ 737 μm and an estimate for the plasma volume was made. The obtained yields of O-radicals (1-4 mole/kWh) are excellent. The conditions to obtain high yields will be discussed.
    Źródło:
    Acta Physica Polonica A; 2009, 115, 6; 1034-1036
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimal allocation of DG units in distribution system considering variation in active power load
    Autorzy:
    Kumar, M.V. Likith
    Bilgundi, Srishail K.
    Pradeepa, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/140424.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    exact loss formula
    loss reduction
    loss sensitivity formula
    optimal DG placement
    uncertainties in active power load
    voltage profile
    Opis:
    High distribution system power-losses are predominantly due to lack of investments in R&D for improving the efficiency of the system and improper planning during installation. Outcomes of this are un-designed extensions of the distributing power lines, the burden on the system components like transformers and overhead (OH) lines/conductors and deficient reactive power supply leading to drop in a system voltage. Distributed generation affects the line power flow and voltage levels on the system equipment. These impacts of distributed generation (DG) may be to improve system efficiency or reduce it depending on the operating environment/conditions of the distribution system and allocation of capacitors. For this purpose, allocating of distributed generation optimally for a given radial distribution system can be useful for the system outlining and improve efficiency. In this paper, a new method is used for optimally allocating the DG units in the radial distribution system to curtail distribution system losses and improve voltage profile. Also, the variation in active power load in the system is considered for effective utilization of DG units. To evidence the effectiveness of the proposed algorithm, computer simulations are carried out in MATLAB software on the IEEE-33 bus system and Vastare practical 116 bus system.
    Źródło:
    Archives of Electrical Engineering; 2019, 68, 2; 265-277
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spin Hamiltonian parameters for Co²⁺ ions in PbMoO₄ crystal - interplay between the fictitious spin S=1/2 and the effective spin S̃ =3/2
    Autorzy:
    Piwowarska, D.
    Kaczmarek, S.
    Gnutek, P.
    Rudowicz, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/1055009.pdf
    Data publikacji:
    2017-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.10.Dg
    71.70.Ch
    61.50.Ah
    61.72.Hh
    76.30.-v
    76.30.Fc
    Opis:
    The interplay between the fictitious spin S' = 1/2 and the effective spin S̃=3/2 for Co²⁺(3d⁷) ions is considered. The available experimental data on the Ze g_{i}' factors for the two Co²⁺ complexes in PbMoO₄ obtained using the fictitious "spin" S'=1/2 description serve for determination of the Zeeman g_{i} factors corresponding to the effective spin S̃ =3/2. The second-rank zero-field splitting parameters D and E (S̃ = 3/2) are also indirectly determined from the experimental EMR data by employing the formulas arising from projection of the g_{i}(S̃=3/2) factors onto the g_{i}'(S' = 1/2) factors. The so-determined second-rank zero-field splitting parameters and g_{i}(S̃ = 3/2) factors will enable comparison with the respective quantities obtained in a subsequent paper using a combined modeling approach.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 1; 73-76
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dangerous Goods Transport Problems in the European Union and Poland
    Autorzy:
    Nowacki, G.
    Krysiuk, C.
    Kopczewski, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/116605.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
    Tematy:
    EU Legislation
    dangerous goods (DG)
    dangerous goods transport
    implementation of EU legislation
    Dangerous Goods Vehicles (DGV)
    Supreme Audit Office (SAO)
    transportation
    Opis:
    The paper refers to threat assessment of dangerous goods (DG) in transportation of the European Union and the Republic of Poland. Dangerous goods in the European Union are carried by inland waterways, rail and road. In Poland 87.5% of DG have been carried by road and 12.5% by rail in 2014. DG can cause an accident and lead to fires, explosions and chemical poisoning or burning with considerable harm to people and the environment. There is not monitoring system in Poland to control in real time road transportation of dangerous goods. Proposition of National System of Monitoring Dangerous Goods in Poland was presented. Realization of mentioned kind of system may significantly contribute to improving safety of people and environment.
    Źródło:
    TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2016, 10, 1; 143-150
    2083-6473
    2083-6481
    Pojawia się w:
    TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effective Field Methods for Magnetic Systems
    Autorzy:
    Kamieniarz, G.
    Dekeyser, R.
    Musiał, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/1930600.pdf
    Data publikacji:
    1994-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.60.Cn
    64.60.Fr
    05.50.+q
    75.10.Dg
    75.10.Hk
    75.10.Jm
    75.40.Cx
    75.40.Mg
    Opis:
    The self-consistency conditions inherent in the mean-field approximation are extended to take into account some pair correlations. Ii is shown that this extension is systematically improvable and applicable to the spin systems with short-range interactions in the entire temperature region. With two correlations included and the renormalization-group ideas implemented, the critical properties of the Ising model are satisfactorily revealed. Moreover, the improved estimates of the thermodynamical quantities for the quantum linear XY model from the finite-size calculations are found down to very low temperatures.
    Źródło:
    Acta Physica Polonica A; 1994, 85, 2; 413-417
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Vibration and Luminescence Spectroscopic Investigations of the Alkali Rare Earth Double Phosphates M$\text{}_{3}$(RE,Eu)(PO$\text{}_{4}$)$\text{}_{2}$ (M=K, Rb; RE=La, Gd)
    Autorzy:
    Kloss, M.
    Schwarz, L.
    Hölsä, J. P. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/1995573.pdf
    Data publikacji:
    1999-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.50.-f
    61.66.Fn
    63.20.-e
    71.20.Dg
    71.20.Eh
    71.70.-d
    78.30.-j
    78.55.-m
    Opis:
    The room temperature IR- and Raman spectra of the different M$\text{}_{3}$RE(PO$\text{}_{4}$)$\text{}_{2}$ (M = K, Rb; RE = La, Eu, Gd) double phosphates were analysed and used to interpret the vibronic side band structure in the photoluminescence spectra. The intraconfigurational 4f-4f electronic transitions in the photoluminescence spectra of the Eu$\text{}^{3+}$ doped M$\text{}_{3}$RE(PO$\text{}_{4}$)$\text{}_{2}$ were analysed in detail. The crystal field fine structure of the $\text{}^{5}$D$\text{}_{0}$ → $\text{}^{7}$F$\text{}_{J}$ (J=0-4) transitions was analysed accounting for the information on the crystal structure. The effect of the temperature as well as the alkali host cation was evaluated. Finally, a preliminary crystal field energy level scheme for the $\text{}^{7}$F$\text{}_{J}$ (J=0-4) ground term was deduced from the analysis of the photo-luminescence as well as IR- and Raman spectra.
    Źródło:
    Acta Physica Polonica A; 1999, 95, 3; 343-349
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An analytical approach for transmission expansion planning with generation variations
    Autorzy:
    Kumar, M.
    Kaur, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/136231.pdf
    Data publikacji:
    2017
    Wydawca:
    EEEIC International Barbara Leonowicz Szabłowska
    Tematy:
    central electricity authority(CEA)
    distributed generation (DG)
    economic index (Ei)
    power system operator (PSO)
    power world simulator (PWS)
    renewable energy sources (RES)
    ransmission expansion planning (TEP)
    Opis:
    Today, the transmission expansion planning for an existing power system under different constraints, is one of the major challenge for power engineers. There are several reasons; one of the reasons is rapid growth in load and inadequate capacity addition. Hence, it is important and essential to implement an algorithm for the transmission expansion which works well and have a good feasibility under certain assumptions and available constraints. Transmission expansion planning used in proposed paper works on an analytical algorithm which has been implemented for specific load condition with variations in generation. For that purpose, an economical factor has been measured that considers economical aspects of the line to be added for expansion. The prescribed analytical approach is also implemented for its feasibility check on a practical case study system.
    Źródło:
    Transactions on Environment and Electrical Engineering; 2017, 2, 2; 72-79
    2450-5730
    Pojawia się w:
    Transactions on Environment and Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A New Diminutive Wide-band MIMO Antenna with Frequency Agile Features for 4G and 5G Diverse Wireless Applications
    Autorzy:
    Mudda, Shivleela
    K M, Gayathri
    Mallikarjun, M
    Powiązania:
    https://bibliotekanauki.pl/articles/27311969.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    Diversity gain (DG)
    Defective ground structure (DGS)
    Fractional bandwidth (FBW)
    ITU (International Telecommunication Union)
    INSAT
    Frequency Reconfigurable antenna (FRA)
    Multiple input multiple output (MIMO)
    mutual coupling
    isolation
    5G
    Envelope correlation coefficient (ECC)
    Opis:
    This paper demonstrates a low-profile, wide-band, two-element, frequency-reconfigurable MIMO antenna that is suitable for diverse wireless applications of 4G and 5G such as WLAN/Bluetooth (2.4–2.5 GHz), WLAN (2.4–2.484 GHz, 5.15– 5.35 GHz, and 5.725–5.825 GHz), WiMAX (3.3–3.69 GHz and 5.25–5.85 GHz), Sub6GHz band proposed for 5G (3.4–3.6 GHz, 3.6-3.8GHz and 4.4–4.99 GHz), INSAT and satellite X-band(6 to 9.6 GHz). Proposed MIMO favour effortless switching between multiple bands ranging from 2.2 to 9.4 GHz without causing any interference. Both antenna elements in a MIMO array are made up of a single module comprised of a slot-loaded patch and a defective structured ground. Two PIN diodes are placed in the preset position of the ground defect to achieve frequencyreconfigurable qualities. The suggested MIMO antenna has a size of 62 ×25 ×1.5 mm3. Previous reconfigurable MIMO designs improved isolation using a meander line resonator, faulty ground structures, or self-isolation approaches. To attain the isolation requirements of modern devices, stub approach is introduced in proposed design. Without use of stub, simulated isolation is 15dB. The addition of a stub improved isolation even more. At six resonances, measured isolation is greater than 18 dB, the computed correlation coefficient is below 0.0065, and diversity gain is over 9.8 dB.
    Źródło:
    International Journal of Electronics and Telecommunications; 2023, 69, 3; 439--448
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical Analysis of Metal-Cylinder-Based Microwave Plasma Module
    Autorzy:
    Sobański, M.
    Jasiński, M.
    Mizeraczyk, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1366115.pdf
    Data publikacji:
    2014-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    88.80.hp
    84.40.-x
    52.35.Hr
    84.40.Dc
    02.70.Dh
    88.30.E-
    52.65.-y
    52.50.Dg
    11.55.-m
    52.40.Fd
    84.40.Az
    Opis:
    We present optimization of energy transfer in the waveguide-supplied metal-cylinder-based microwave plasma module with an inner cylindrical quartz tube. The construction of microwave plasma module is based on a WR 340 waveguide standard. Presented microwave plasma module operates at atmospheric pressure and frequency of 2.45 GHz. There is a reduced height section waveguide in microwave plasma module which provides local increase of the electric field in the plasma region. Microwave plasma module is terminated with a movable plunger which plays the role of the tuning element. Tuning characteristics of microwave plasma module are defined as the dependence of the $P_{R}$/$P_{I}$ on the position $l_{s}$ of the movable plunger, where $P_{R}$ and $P_{I}$ are the microwave power reflected and power incident, respectively. The powers $P_{R}$ and $P_{I}$ are measured in the input plane of microwave plasma module. The purpose of the presented optimization is to achieve $P_{R}$ lower than 5% of $P_{I}$ in widest range of position of movable plunger $l_{s}$. We used Comsol Multiphysics software to make numerical analysis which allows to optimize the parameters of microwave plasma module. Results of numerical analysis show that $P_{R}$/$P_{I}$ is lower than 0.05 in a wide range of movable plunger position $l_{s}$.
    Źródło:
    Acta Physica Polonica A; 2014, 125, 6; 1309-1311
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-87 z 87

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