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Wyszukujesz frazę "Dobrowolski, M." wg kryterium: Autor


Tytuł:
Verification of ideological classifications - a statistical approach
Autorzy:
Mazurkiewicz, M.
Mercik, J.
Dobrowolski, W.
Powiązania:
https://bibliotekanauki.pl/articles/206009.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
ładowanie początkowe
przestrzeń ideologiczna
wymiar ideologiczny
bootstrap
ideological dimension
ideological space
Opis:
The paper presents a statistical method of verifying ideological classifications of votes. Parliamentary votes, preclassified by an expert (on a chosen subset), are verified at an assumed significance level by seeking the most likely match with the actual vote results. Classifications that do not meet the requirements defined are rejected. The results obtained can be applied in the ideological dimensioning algorithms, enabling ideological identification of dimensions obtained.
Źródło:
Control and Cybernetics; 2001, 30, 4; 451-463
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of "As-Prepared" and Chemically Modified Multiwalled Carbon Nanotubes
Autorzy:
Kuryliszyn-Kudelska, I.
Małolepszy, A.
Mazurkiewicz, M.
Stobinski, L.
Dobrowolski, W.
Powiązania:
https://bibliotekanauki.pl/articles/2047920.pdf
Data publikacji:
2011-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.48.De
81.20.Ym
75.75.-c
Opis:
In this work we have studied the structural and magnetic properties of "as-prepared" multiwalled carbon nanotubes, synthesized by the chemical vapor deposition method, and chemically modified multiwalled carbon nanotubes. Transmission electron microscopy was used to show multiwalled carbon nanotubes structure. The results of systematic magnetic property measurements on multiwalled carbon nanotubes are presented. The static and dynamic magnetic responses, such as the temperature dependence of the linear AC susceptibility and DC magnetization up to 9 T were studied. We have observed significant changes in magnetic AC susceptibility and magnetization for "as-prepared" and chemically modified multiwalled carbon nanotubes samples.
Źródło:
Acta Physica Polonica A; 2011, 119, 5; 597-599
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fermi Level Position in GaMnAs - a Thermoelectric Study
Autorzy:
Osinniy, V.
Jędrzejczak, A.
Arciszewska, M.
Dobrowolski, W.
Story, T.
Sadowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2027483.pdf
Data publikacji:
2001-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Ck
75.30.Et
73.50.-h
Opis:
Thermoelectric power was studied in the temperature range 100≤ T≤300 K in 0.3-1μm thick ferromagnetic Ga$\text{}_{1-x}$Mn$\text{}_{x}$As epitaxial layers (0.015≤ x≤0.06) in order to determine Fermi energy E$\text{}_{F}$ and carrier concentration p. For 0.015≤ x≤0.05, at T=273 K we find E$\text{}_{F}$=275±50 meV and p=(2.5± 0.5)×10$\text{}^{20}$ cm$\text{}^{-3}$ (approximately Mn content independent). For x= 0.06, the Fermi energy decreases by about 100 meV with the corresponding reduction of hole concentration to p=1.2×10$\text{}^{20}$ cm$\text{}^{-3}$. At T=120 K, these parameters vary between E$\text{}_{F}$=380 meV and p=3.5×10$\text{}^{20}$ cm$\text{}^{-3}$ for x=0.015 to E$\text{}_{F}$=110 meV and p=5×10$\text{}^{19}$ cm$\text{}^{-3}$ for x=0.06.
Źródło:
Acta Physica Polonica A; 2001, 100, 3; 327-334
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetotransport Study of MBE grown Pb$\text{}_{1-x}$Eu$\text{}_{x}$Se Epilayers
Autorzy:
Dobrowolski, W.
Grodzicka, E.
Story, T.
Lambrecht, A.
Bottner, H.
Tacke, M.
Powiązania:
https://bibliotekanauki.pl/articles/1950743.pdf
Data publikacji:
1996-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Le
73.50.Jt
Opis:
Hall effect and electron conductivity investigations of MBE grown epilayers of Pb$\text{}_{1-x}$Eu$\text{}_{x}$Se (0 ≤ x ≤ 0.06) as a function of temperature and magnetic field are reported. The strong Hall coefficient dependence on the magnetic field was found for p-type samples grown with Se excess. The possible origins of this effect are discussed.
Źródło:
Acta Physica Polonica A; 1996, 90, 4; 759-762
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Frequency Raman Spectrum οf Bulk $Zn_{0.984}Co_{0.016}O$ Crystal
Autorzy:
Szuszkiewicz, W.
Łusakowski, A.
Morhange, J.
Gołacki, Z.
Arciszewska, M.
Brodowska, B.
Kanehisa, M.
Klepka, M.
Dobrowolski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1807848.pdf
Data publikacji:
2009-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
78.30.Fs
Opis:
The influence of possible presence of $Co^{2+}$ ion pairs in a bulk $Zn_{1-x}Co_{x}O$ mixed crystal on the low-frequency part of the Raman spectrum is discussed. Two effects can be taken into account in the theoretical considerations when analyzing the energy level scheme corresponding to Co ions. The first is a local lattice deformation in the vicinity of $Co^{2+}$ ion due to a presence of the second ion, smaller than the host ZnO lattice cation. Such deformation creates a trigonal field, which can only slightly modify the energy levels of $Co^{2+}$ ion. The second effect, which results from an antiferromagnetic superexchange interaction between two $Co^{2+}$ ions is responsible for a new set of energy levels. The Raman data taken at low temperature on the sample corresponding to the composition x = 0.016 demonstrated the presence of two structures at about 6 $cm^{-1}$ and 13 $cm^{-1}$. These structures may be interpreted as electronic transitions between the ground state and the first excited state of a single $Co^{2+}$ ion in the substitution site of ZnO lattice and as a similar transition for $Co^{2+}$ ion pair, respectively.
Źródło:
Acta Physica Polonica A; 2009, 116, 1; 103-106
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Susceptibility of Cd$\text{}_{1-x}$Fe$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{y}$
Autorzy:
Arciszewska, M.
Mycielski, A.
Dobrowolski, W.
Lenard, A.
Mauger, A.
Witkowska, B.
Powiązania:
https://bibliotekanauki.pl/articles/1890693.pdf
Data publikacji:
1991-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ey
75.20.Hr
75.30.Cr
Opis:
Magnetic susceptibility of Cd$\text{}_{1-x}$Fe$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{y}$ was found to consist of Van Vleck term (characteristic for the Fe$\text{}^{2+}$ centers in tetrahedral crystal symmetry) and temperature-dependent contribution. The occurrence of the latter indicates an existence of additional magnetic moments. We ascribe their origin to the modification of the Fe$\text{}^{2+}$ energy level spectrum induced by mixed Te-Se anion environment.
Źródło:
Acta Physica Polonica A; 1991, 80, 2; 303-306
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
AC Magnetic Susceptibility Studies of $Ge_{1-x-y}Sn_{x}Mn_{y}Te$ Mixed Crystals
Autorzy:
Kilanski, L.
Arciszewska, M.
Domukhovski, V.
Dobrowolski, W.
Slynko, V.
Slynko, I.
Powiązania:
https://bibliotekanauki.pl/articles/1811934.pdf
Data publikacji:
2008-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Fr
72.80.Ga
75.40.Gb
75.50.Lk
75.50.Pp
Opis:
We present preliminary studies of magnetic and transport properties of $Ge_{1-x-y}Sn_xMn_yTe$ mixed crystals with 0.091 ≤ x ≤ 0.105 and 0.012 ≤ y ≤ 0.115. Qualitative analysis of our experimental results showed the appearance of a spin-glass phase at T < 50 K. The transport characterization (resistivity and Hall effect measurements) showed that the investigated samples had semimetallic p-type conductivity with relatively large carrier concentrations (p > $10^{21} cm^{-3}$) and low mobilities (μ < 100 $cm^2 V^{-1} s^{-1}$). The dependence of transport properties on the chemical composition of the samples was observed.
Źródło:
Acta Physica Polonica A; 2008, 114, 5; 1145-1150
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural and Electrical Properties of SiC Grown by PVT Method in the Presence of the Cerium Vapor
Autorzy:
Avdonin, A.
Racka, K.
Tymicki, E.
Grasza, K.
Jakieła, R.
Pisarek, M.
Dobrowolski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1399070.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.F-
61.72.-y
81.10.Bk
61.72.uf
Opis:
The results of investigation of structural and electrical properties of bulk SiC crystals, which were grown by physical vapor transport method with different Ce impurity content added to the SiC source material, are presented. The gradual dosage of cerium from the SiC source and continuous presence of the cerium vapor over the SiC crystallization fronts during the crystal growth processes are confirmed. The cerium influences the overall concentration of structural defects. The increase of the concentration of both, donors and acceptors, and appearance of new shallow donors (15-32 meV) in 4H-SiC crystals are observed.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 761-764
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of Sn$\text{}_{1-x}$Gd$\text{}_{x}$Te (0.002 ≤ x ≤ 0.09)
Autorzy:
Story, T.
Arciszewska, M.
Dobrowolski, W.
Gołacki, Z.
Górska, M.
Grodzicka, E.
Łusakowski, A.
Dynowska, E.
Witkowska, B.
Powiązania:
https://bibliotekanauki.pl/articles/1952098.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Ck
75.30.Et
Opis:
Magnetic, transport and structural properties of bulk crystals of Sn$\text{}_{1-x}$Gd$\text{}_{x}$Te with Gd content 0.002 < x < 0.09 and varying carrier concentrations obtained by an isothermal annealing were studied in the temperature range T = 1.5 - 80 K. We found the effect of resonant increase in antiferromagnetic spin-spin exchange interactions in the crystals with 0.025 ≤ x ≤ 0.05. No effect was found in crystals either with higher (x > 0.05) or with lower (x < 0.025) Gd concentration. The observed Gd composition dependence of the magnetic and transport properties of SnGdTe can be explained in a proposed model relating these experimental properties to the Gd composition induced shift of the position of Gd$\text{}^{3+}\text{}^{/}\text{}^{2+}$ level with respect to the top of the valence band of SnGdTe.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 935-938
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transport and Magnetic Study of Gd Ions in Pb$\text{}_{1-y}$Sn$\text{}_{y}$Te
Autorzy:
Story, T.
Arciszewska, M.
Łazarczyk, P.
Łusakowski, A.
Górska, M.
Dobrowolski, W.
Witkowska, B.
Grodzicka, E.
Gałązka, R. R.
Powiązania:
https://bibliotekanauki.pl/articles/1968424.pdf
Data publikacji:
1997-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Ck
75.30.Et
Opis:
Electric conductivity, Hall effect and magnetic susceptibility of Pb$\text{}_{1-x-y}$ Sn$\text{}_{y}$Gd$\text{}_{x}$Te mixed crystals with 0.13 ≤ y ≤ 0.93 and 0.001 ≤ x ≤ 0.04 were experimentally studied over the temperature range 4K ≤ T ≤ 300 K. The incorporation of Gd ions into the Pb$\text{}_{1-y}$Sn$\text{}_{y}$Te matrix results in semi-metallic n-type conductivity of the crystals with y < 0.6. For crystals with y > 0.6 one observes only semi-metallic p-type conductivity. We present a model explaining these results in terms of the Sn composition dependence of the location of Gd$\text{}^{2+}\text{}^{/}\text{}^{3+}$ level with respect to the band edges of PbSnGdTe.
Źródło:
Acta Physica Polonica A; 1997, 92, 5; 997-1000
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Resonant State of 4f$\text{}^{14}\text{}^{/}\text{}^{13}$ Yb Ion in Pb$\text{}_{1-x}$Ge$\text{}_{x}$Te
Autorzy:
Grodzicka, E.
Dobrowolski, W.
Story, T.
Slynko, E. T.
Vygranenko, Yu.K.
Willekens, M. M. H.
Swagten, H. J. M.
de Jonge, W. J. M.
Powiązania:
https://bibliotekanauki.pl/articles/1950801.pdf
Data publikacji:
1996-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Ht
75.20.Ck
Opis:
The study of transport and of magnetic properties of Pb$\text{}_{1-x}$Ge$\text{}_{x}$Te:Yb mixed crystals (0 ≤ x ≤ 0.04) is reported. It is shown that Yb forms a donor state resonant with the PbTe valence band. The donor state position may be tuned (shifted relative to the energy gap) by admixture of Ge. The properties of the Yb ion in the Pb$\text{}_{1-x}$Ge$\text{}_{x}$Te matrix makes the system unique from the point of view of magnetic properties. It is demonstrated that the change of the conductivity type from p to n induces transitions from the paramagnetic state to the diamagnetic one.
Źródło:
Acta Physica Polonica A; 1996, 90, 4; 801-804
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Manifestation of Spin-Glass-Like Behavior in the Organometallic Magnet
Autorzy:
Dyakonov, V. P.
Arciszewska, M.
Dobrowolski, W.
Szewczyk, A.
Szymczak, H.
Aksymentieva, E.
Varyukhin, V.
Zubov, E.
Gutowska, M. U.
Powiązania:
https://bibliotekanauki.pl/articles/2013705.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.40.Cx
Opis:
Ac susceptibility (χ$\text{}_{ac}$) and dc magnetization (M$\text{}_{dc}$) of the organometallic magnet Na[FeO$\text{}_{6}$(C$\text{}_{10}$H$\text{}_{8}$N)$\text{}_{3}$] have been studied in temperature range of 4.2-200 K, in an external magnetic field up to 16 kOe. Some peculiarities of the χ$\text{}_{ac}$ and M $\text{}_{dc}$ behavior, which are characteristic of spin-glasses, e.g. cusps in the susceptibility and zero-field-cooled magnetization, an irreversibility between the field-cooled and zero-field-cooled magnetization and dependences of the T$\text{}_{cusp}$ temperature on the frequency and the intensity of the magnetic field, were observed at low temperatures.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 863-866
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of $Sn_{1-x}Cr_xTe$ Diluted Magnetic Semiconductors
Autorzy:
Kilanski, L.
Podgórni, A.
Górska, M.
Dobrowolski, W.
Slynko, V.
Slynko, E.
Reszka, A.
Kowalski, B.
Powiązania:
https://bibliotekanauki.pl/articles/1399145.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ga
75.30.Hx
75.30.Et
75.50.Pp
Opis:
We present the studies of $Sn_{1-x}Cr_xTe$ semimagnetic semiconductors with chemical composition x ranging from 0.004 to 0.012. The structural characterization indicates that even at low average Cr-content x ≤q 0.012, the aggregation into micrometer size clusters appears in our samples. The magnetic properties are affected by the presence of clusters. In all our samples we observe the transition into the ordered state at temperatures between 130 and 140 K. The analysis of both static and dynamic magnetic susceptibility data indicates that the spin-glass-like state is observed in our samples. The addition of Cr to the alloy seems to shift the spin-glass-like transition from 130 K for x = 0.004 to 140 K for x = 0.012.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 881-884
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
$Zn_{1-x}(Mn,Co)_xGeAs_2$ Ferromagnetic Semiconductor: Magnetic and Transport Properties
Autorzy:
Kilanski, L.
Gorska, M.
Domukhovski, V.
Dobrowolski, W.
Anderson, J.
Rotundu, C.
Varniavskii, S.
Marenkin, S.
Powiązania:
https://bibliotekanauki.pl/articles/1811937.pdf
Data publikacji:
2008-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Fr
72.80.Ga
75.50.Pp
75.40.Cx
Opis:
We present the studies of magnetic and transport properties of the bulk $Zn_{1-x}(Mn, Co)_xGeAs_2$ mixed crystals with 0.052 ≤ x ≤0.182 grown using direct fusion method. Magnetic investigations showed that for samples with x ≥ 0.078 we observed a behavior typical of ferromagnets, with the Curie temperatures $T_C$ ≥ 300 K. The observed ferromagnetism was probably connected with the spinodal decomposition of the Mn ions in the alloy. The transport studies including resistivity and Hall effect (at B=1.4 T) were performed. The samples showed p-type conductivity with semiconducting or metallic character, depending on the alloy composition. The Hall carrier concentration, p ≥ $10^{18} cm^{-3}$, was composition dependent.
Źródło:
Acta Physica Polonica A; 2008, 114, 5; 1151-1157
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Raman Scattering from ZnO(Fe) Nanoparticles
Autorzy:
Romčević, N.
Kostić, R.
Romčević, M.
Hadžić, B.
Kuryliszyn-Kudelska, I.
Dobrowolski, W.
Narkiewicz, U.
Sibera, D.
Powiązania:
https://bibliotekanauki.pl/articles/1811980.pdf
Data publikacji:
2008-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.-e
78.30.Fs
78.67.-n
Opis:
Nanocrystalline samples of ZnO(Fe) were synthesized by wet chemical method. Samples were characterized by X-ray diffraction to determine composition of the samples (ZnO, Fe₂O₃, ZnFe₂O₄) and the mean crystalline size (8-52 nm). In this paper we report the experimental spectra of the Raman scattering (from 200 to $1600 cm^{-1}$). Main characteristics of experimental Raman spectrum in 200 to $1600 cm^{-1}$ spectral region are: sharp peak at $436 cm^{-1}$ and broad two-phonon structure at ≈ $1150 cm^{-1}, typical of ZnO;broad structure below $700 cm^{-1}$ that has different position and shape in case of ZnFe₂O₄ or Fe₂O₃ nanoparticles.
Źródło:
Acta Physica Polonica A; 2008, 114, 5; 1323-1328
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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