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Wyświetlanie 1-15 z 38
Tytuł:
Reliability analysis of forest machines due to FMEA method
Autorzy:
Ťavoda, P.
Kováč, J.
Łukaszczyk, Z. Ł.
Powiązania:
https://bibliotekanauki.pl/articles/409738.pdf
Data publikacji:
2018
Wydawca:
STE GROUP
Tematy:
reliability
FMEA method
forest machines
maintenance
Opis:
The article deals with the research of operational reliability of forest felling machines with the method FMEA (Failure Mode and Effect Analysis) and its implementation for observed machines in the organization. Forwarders 810D by John Deere were chosen for this research. The research was realized in real operational conditions. Application of the FMEA method allows flexibility in case of unexpected situations and optimization of human potential abilities. FMEA tool is a tool preventing outages operational reliability and preventive tool for ensuring the maintenance of facilities. This paper explores and verifies the operational reliability theory in practical real-world conditions, resulting in a reduction in operating (variable) costs, minimization of failures and readiness and increased performance of observed machines.
Źródło:
Management Systems in Production Engineering; 2018, 4 (26); 200-206
2299-0461
Pojawia się w:
Management Systems in Production Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of 1D Ordering on Magnetic Properties of Iron Nanoparticles coated by Silica Shell
Autorzy:
Zeleňáková, A.
Hrubovčák, P.
Zeleňák, V.
Kováč, J.
Powiązania:
https://bibliotekanauki.pl/articles/1030766.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.75.Fk
68.37.Og
Opis:
Peculiar magnetic properties of 1D arranged composite consisting of Fe nanoparticles coated by insulating SiO2 layer were studied. Silica layer promotes the self-organization of 4 nm iron nanoparticles to the chain-like structures. Magnetization study shows that prepared nanoparticles exhibit very strong inter-particle magnetic interactions, which lead to long-range ordering of nanoparticles magnetic moments. Magnetic properties show superferromagnetic behaviour. The low value of room temperature coercivity, the existence of electrical insulating silica layer and small size of iron nanoparticles favour studied material for potential usage in microelectronic devices designed for high voltage signals modulated by high frequencies.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 561-563
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superparamagnetism in Cobalt Nanoparticles Coated by Protective Gold Layer
Autorzy:
Hrubovčák, P.
Zeleňáková, A.
Zeleňák, V.
Kováč, J.
Powiązania:
https://bibliotekanauki.pl/articles/1368320.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.75.Fk
68.37.Og
Opis:
In this work we present the study on structural and magnetic properties of fine cobalt nanoparticles coated by protective gold layer synthetized by microemulsion method. Structural measurements (powder XRD, HRTEM) confirmed spherical shape of the particles, their nanocrystalline character and presence of individual Co and Au phases. Investigation of magnetic properties of the particles revealed superparamagnetic behavior at higher temperatures and magnetic hysteresis at low temperatures. Average magnetic moment of individual particle $m_{p}~86.3μ_{B}$ was established. The critical temperature, below which the magnetic moments of the particles are blocked, was $T_{B}$=6 K. Investigation of magnetic relaxation processes via magnetic susceptibility, detected one maximum attributed to single relaxation process, present in the particles. Obtained data, interpreted in terms of Neél-Arrhenius and Vogel-Fulcher theoretical models, confirmed the presence of strong magnetic interparticle interactions.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 216-217
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Clean bulk YBaCuO superconductors doped by paramagnetic ions of Sm and Yb
Autorzy:
Jirsa, M.
Volochová, D.
Kováč, J.
Diko, P.
Powiązania:
https://bibliotekanauki.pl/articles/1054700.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Ha
74.25.Op
74.25.Sv
74.60.Ge
74.72.-h
Opis:
The recently developed clean cuprate technology was employed to study the effect of tiny amounts of paramagnetic Yb and Sm ions on electromagnetic properties of bulk YBaCuO. Small samples of about 1.5×1.5×0.5 mm³ were measured by vibrating sample magnetometer in the field range ±9 T and temperatures 30 K to 10 K in the non-superconducting tetragonal state and 300 K to 70 K in the orthorhombic, superconducting state. In the latter case, we observed the reversible paramagnetic moment above T_{C}, similar as in the tetragonal state. Below T_{C} an irreversible magnetic moment was observed from which critical current density, J_c, was evaluated using the extended Bean model. The effect of doping by Yb and Sm ions on J_c was studied and a correlation between J_c and the total paramagnetic moment was found. Both J_c(B) and the normalized pinning force density as a function of the reduced magnetic field were analyzed in terms of the classical model and discussed with respect to the material anisotropy, giving us at least a rough idea on the type of the effective pinning type and mechanism.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1027-1029
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Charcoal Supporting Silver as a Water Disinfectant
Autorzy:
Valušová, E.
Antalík, M.
Pristaš, P.
Javorský, P.
Kováč, J.
Timko, M.
Powiązania:
https://bibliotekanauki.pl/articles/1201874.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Ni
75.60.Ej
75.47.Lx
81.05.U-
92.40.qc
Opis:
We investigated the magnetic behavior of charcoal composite with incorporated magnetite and silver ions. The magnetization curve measured at 282 K showed saturation magnetization of 8 emu/g. By benefiting from a mechanical process, the magnetic activated carbon, supporting silver ions (MCAG), acts as a magnetic filter uptaking the bacteria. This idea was confirmed by the DGGE analysis in which the bacterial DNA was detectable in the sediment after the treatment.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 226-227
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Crystalline Structure, Stoichiometry and Magnetic Properties of the Morasko Meteorite
Autorzy:
Idzikowski, B.
Kováč, J.
Diko, P.
Stankowski, W.
Muszyński, A.
Powiązania:
https://bibliotekanauki.pl/articles/1535541.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
91.65.Sn
75.50.Bb
67.80.dk
Opis:
The composition and structure of iron-nickel alloys smithereens extracted from the Morasko (Poland) Meteorite (fell ∿ 5 ka BP) were investigated by optical metallographic techniques, scanning electron microscopy and electron microprobe analysis, thermal analyses, magnetic measurements and X-ray diffraction. Microstructural analysis by scanning electron microscopy and optical microscopy has shown that the sample is composed from large grains of Fe-Ni alloy in which secondary phase crystals with well developed crystal habits and the size about 10 micrometers are distributed. Thermal analyses confirmed that the transformation from alpha to gamma Fe-Ni solid solution appearing as a function of temperature corresponds to about 5 wt% Ni in the Fe-Ni alloy. Possible scenario of the extraterrestrial sample solidification is related to the microstructural and magnetic behavior.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 1071-1073
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Co Doping on Induced Anisotropy and Domain Structure in Magnetic Field Annealed $(Fe_{1-x}Co_x)_{79}Mo_8Cu_1B_{12}$
Autorzy:
Kunca, B.
Marcin, J.
Švec, P.
Kováč, J.
Švec Sr., P.
Škorvánek, I.
Powiązania:
https://bibliotekanauki.pl/articles/1398273.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Gw
75.50.Tt
75.60.Ch
75.60.Nt
Opis:
The effect of heat treatment in applied magnetic field on the induced anisotropy and domain structure of $(Fe_{1-x}Co_x)_{79} Mo_8 Cu_1 B_{12}$ (x=0, 0.2, 0.5) nanocrystalline alloy system was investigated. A heat treatment of Co-doped samples under the application of longitudinal magnetic field resulted in squared hysteresis loops characterized by very low coercive field values. Sheared loops with tunable slope and good field linearity were obtained after annealing in transverse magnetic field. Corresponding domain structure showed uniform character, oriented in the direction parallel or perpendicular to the ribbon axis after longitudinal or transverse magnetic field annealing, respectively. No effect of magnetic field annealing was found in Co-free sample. Correlations between Co-doping, the Curie temperature, and soft magnetic properties after magnetic field annealing are discussed.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 759-761
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of Composites Consisting of High-T$\text{}_{c}$ Superconductor and Fine Magnetic Particles
Autorzy:
Timko, M.
Kopčanský, P.
Kováč, J.
Koneracká, M.
Plecháček, V.
Powiązania:
https://bibliotekanauki.pl/articles/2013009.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.Hs
75.50.Tt
Opis:
The composite systems as a mixture of fine magnetic particles of Fe$\text{}_{3}$O$\text{}_{4}$ and superconducting powder such as Bi$\text{}_{1.8}$Pb$\text{}_{0.2}$Sr$\text{}_{2}$Ca$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{10+x}$ were prepared. The influence of internal magnetic field (generated by magnetic particles) on the superconducting properties of prepared composites were studied as a function of concentration of magnetic particles and their magnetic state. The observed data both of the shielding and the Meissner effect were compared with corresponding linear combination of pure signals of magnetite and superconductor, respectively. The large differences were observed for demagnetized samples. It means that result must be discussed in the frame of the distribution of internal magnetic field created by the magnetic particles.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 389-392
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of spark plasma sintering on microstructure and properties of bulk LaCaSrMnO magnetocaloric materials
Autorzy:
Zmorayová, K.
Antal, V.
Kováč, J.
Diko, P.
Noudem, J.
Powiązania:
https://bibliotekanauki.pl/articles/1053176.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
61.72.-y
75.30.Kz
77.80.B-
81.70.Pg
81.20.Ev
81.30.Fb
Opis:
Polycrystalline La_{0.67}Ca_{0.33-x}Sr_xMnO₃ (x=0.33, 0.03, 0) (LCSM) perovskite samples treated by spark plasma sintering technique were investigated. This study proved influence of the sintering temperature on microstructure of these perovskite ceramics. The thermogravimetric measurements revealed the possibility of increase of oxygen content in studied LCSM samples by additional annealing under oxygen atmosphere and low temperature. Finally, the effect of this annealing on magnetic properties was demonstrated.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 804-806
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of Mechanochemically Synthesized Mixed Oxides
Autorzy:
Kostova, N.
Zorkovská, A.
Kováč, J.
Velinov, N.
Baláž, P.
Powiązania:
https://bibliotekanauki.pl/articles/1372521.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.84.Bw
75.60.-d
76.80.+y
61.05.cp
81.07.Wx
Opis:
The mixed oxides $Fe_{2}O_{3}-ZnO$ have been obtained in nanocrystalline state by reactive milling in a high-energy planetary mill, from a stoichiometric mixture of hematite and ZnO. The magnetic properties of samples were evaluated by magnetization measurements and Mössbauer spectrometry. A post milling annealing promotes the solid state reaction and improves the zinc ferrite formation, paramagnetic $ZnFe_{2}O_{4}$ phase is formed. Further mechanical activation leads to structural transformation into Wüstite-type (FeZn)O mixed oxide, with ferromagnetic hysteresis and increased magnetization.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 411-412
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and Characterization of Magnetoferritin
Autorzy:
Mitróová, Z.
Melníková, L.
Kováč, J.
Timko, M.
Kopčanský, P.
Powiązania:
https://bibliotekanauki.pl/articles/1429123.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Cr
75.50.Ee
75.60.Ej
75.50.Tt
Opis:
The paper presents detailed experimental study of synthesis and characterization a bioinorganic magnetic molecule - magnetoferritin. Magnetoferritin with loading of iron ions per protein molecule in the range from 300 to 3000 was prepared. Size distribution analysis (transmission electron microscopy, dynamic light scattering) shows spherical nanoparticles with particle size distribution from 2 to 12 nm, and hydrodynamic diameter from 12 to 25 nm. The thermomagnetic curves measured after cooling the sample in zero field (zero-field cooling) and under the presence of the measurement field (field cooling) show superparamagnetic behavior with the blocking temperature $T_{b}$ from 22 to 60 K and the magnetization loops measured below $T_{b}$ (at 2 K) show the hysteresis with coercive field from 20 to 30 kA/m depending on the concentration of the magnetic nanoparticles.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1318-1320
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of Sm addition on the microstructure and superconducting properties of YBCO bulk superconductors
Autorzy:
Volochová, D.
Diko, P.
Piovarči, S.
Antal, V.
Kováč, J.
Jirsa, M.
Powiązania:
https://bibliotekanauki.pl/articles/1054772.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.62.Dh
81.10.Fq
61.72.-y
74.25.Ha
74.25.Sv
Opis:
The effect of Sm addition on the microstructure and superconducting properties of Y-Ba-Cu-O (YBCO) bulk superconductors has been studied. Nominal composition: 1 mol YBa₂Cu₃O_{7-δ} + 0.25 mol Y₂O₃ + 1 wt% CeO₂ was enriched with different amounts of SmBa₂Cu₃O_y powder with the aim to increase critical current density, J_c, especially in higher magnetic fields by introducing additional pinning centers. Single grain YBCO bulk superconductors with SmBa₂Cu₃O_y (Y123-Sm) addition were prepared by the optimized top seeded melt growth process. Microstructure analysis, performed by polarized light microscope, revealed that SmBa₂Cu₃O_y addition leads to a higher amount of slightly coarser Y₂BaCuO₅ particles, which is related to lower critical current densities (J_c ≈ 6×10⁴ A/cm²) of the YBCO samples with SmBa₂Cu₃O_y addition in low magnetic fields. On the other hand, an enhancement of critical current density, J_c, in higher magnetic fields was observed for Y123-Sm samples. Moreover, a maximum trapped magnetic field, B_{tmax}, of 564 mT at 77 K in Y123-Sm, x=0.0025 sample (Ø 17.2 mm) was 43% higher than that for YBCO sample without any addition.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1009-1011
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preparation and Complex Characterization of Magnetic Nanoparticles in Magnetic Fluid
Autorzy:
Kubovčíková, M.
Antal, I.
Kováč, J.
Závišová, V.
Koneracká, M.
Kopčanský, P.
Powiązania:
https://bibliotekanauki.pl/articles/1201928.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.75.Fk
78.67.Bf
36.40.Cg
47.65.Cb
75.50.Mm
75.30.Cr
Opis:
This paper deals with the preparation and complex characterization of magnetite nanoparticles (MNPs), stabilized with sodium oleate (SO), by the routine methods such as infrared spectroscopy (FTIR), magnetic measurements, scanning electron microscopy (SEM) and dynamic light scattering (DLS). The FTIR spectra showed that SO molecules were linked to MNPs through chemical bonding. Magnetic measurements proved that the MNPs are superparamagnetic in nature. Four different methods were used to determine the size and size distribution of the MNPs: SEM, DLS, differential centrifugal sedimentation (DCS) and magnetic measurements. SEM analysis showed a relatively narrow size distribution of roughly spherical MNPs with a mean diameter of 61 nm. DLS analysis confirmed monodispersed MNPs production with hydrodynamic diameter of 75 nm. The size distribution determined by DCS was found to be 69 nm. Finally, the calculated magnetic core diameter obtained from magnetization curve was 10 nm. The obtained results demonstrate that SO coated MNPs fulfil the requirements for a useful drug delivery system.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 268-269
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical Current Density and Microstructure of $NdBa_2Cu_3O_7$ Single Crystal
Autorzy:
Diko, P.
Zmorayová, K.
Šefčiková, M.
Antal, V.
Kováč, J.
Yao, X.
Powiązania:
https://bibliotekanauki.pl/articles/1535339.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Ha
74.25.Sv
74.62.Bf
Opis:
The top-seeded solution growth method was used to grow NdBCOss single crystals in air. The microstructure of the samples has shown that the oxygenation crack structure developed in the single crystals. The intrinsic critical current density was estimated to be at least twice higher than the value of volume critical current density determined from the magnetization measurements.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 1028-1030
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanochemically Synthesized CuFeSe₂ Nanoparticles and Their Properties
Autorzy:
Dutková, E.
Škorvánek, I.
Sayagués, M.
Zorkovská, A.
Kováč, J.
Baláž, P.
Powiązania:
https://bibliotekanauki.pl/articles/1032137.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Hd
81.07.Wx
81.20.Wk
Opis:
The mechanochemical synthesis of nanocrystalline CuFeSe₂ particles prepared by high-energy milling in a planetary mill in an argon atmosphere from copper, iron, and selenium for 60 min is reported for the first time. The CuFeSe₂ nanoparticles crystallize in tetragonal structure with mean crystallite size of about 32±1 nm. High resolution transmission electron microscopy measurements confirmed the presence of agglomerates which are formed by small nanocrystalline domains (5-40 nm). The magnetic data revealed that paramagnetic CuFeSe₂ nanoparticles coexist with a small amount of ferromagnetic impurities at room temperature. The magnetic transition towards a weak ferromagnetic or ferrimagnetic behavior occurs in CuFeSe₂ at approximately 79 K. The band gap of the CuFeSe₂ particles is 0.95 eV which is wider than the band gap in bulk materials (0.16 eV), which could be in many aspects of application more beneficial.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1156-1158
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 38

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