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11.
In this paper the lightning current function proposed by Heidler is approximated by a linear combination of exponential functions in the time domain, which is afterward analytically transformed into the frequency domain. The unknown coefficients of the exponential approximation for the most frequently used values of the current steepness factor are computed using the least squares method. The developed exponential approximation is general with respect to the current steepness factor in the Heidler function. Approximation of the Heidler function with a linear combination of exponential functions enables the approximation of various Heidler function based lightning current functions. Heidler function in the frequency domain can be used for transient analysis of electromagnetic phenomena that include lightning protection, grounding grid analysis and electromagnetic compatibility problems. 相似文献
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Nemanja M. Gavrilov Igor A. Pašti Jugoslav Krstić Miodrag Mitrić Gordana Ćirić-Marjanović Slavko Mentus 《Ceramics International》2013,39(8):8761-8765
Single phase tungsten carbide nanoparticles (WC-NPs), (mean particle diameter 5.4 nm), distributed over carbonized polyaniline (C-PANI) nanotubes/nanosheets were synthesized by a solid state reaction between WO3 and nitrogen-rich carbonized polyaniline at 1000 °C in a reducing atmosphere. The resulting composite was characterized by X-ray diffractometry, electron microscopy, thermogravimetry in oxidizing and reduction atmospheres and elemental analysis. We suggested that the synthesis of WC as a single phase was facilitated by reactive C atoms with dangling bonds, formed upon nitrogen removal. 相似文献
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Süleyman Kahraman Mateja Podlogar Slavko Bernik Hüsnü Salih Güder 《Metallurgical and Materials Transactions A》2014,45(4):2326-2334
Copper zinc tin sulfide (Cu2ZnSnS4) has been receiving a lot of attention in recent years as a new, alternative absorber for the production of cheap thin film solar cells owing to the high natural abundance of all the constituents, its tunable direct-band-gap energy, and its large optical absorption coefficient. In addition, to overcome the problem of expensive vacuum-based methods, solution-based approaches are being developed for Cu2ZnSnS4 deposition. In this study, Cu2ZnSnS4 thin films were grown on soda lime glass substrates via the sulfurization of solution grown Cu2SnS3/ZnS stacked sulfide layers. A new facile route to overcome the difficulty of depositing Cu2ZnSnS4 thin film with a desired stoichiometric composition in a single cation solution has been presented. The influences of deposition cycles of layers on the morphological, compositional, structural, and optical properties of the samples were investigated. It was observed from scanning electron microscopy (SEM) images that the films were continuous and composed of homogenously distributed large grains. Possible chemical formulations of the best samples were predicted to be Cu1.99Zn1.25Sn1.00S3.76 and Cu1.97Zn1.03Sn1.29S3.71 via energy-dispersive X-ray spectroscopy (EDXS) results. The X-ray diffraction (XRD) patterns of the samples matched very well with the reference values. The Raman-scattering analysis of the films proved the phase purity of the CZTS samples. The optical absorption coefficient of the films was found to be about 104 cm?1 based on absorbance spectroscopy. The optical band gaps of the films were estimated to be between 1.36 and 1.50 eV. From these we are able to conclude that CZTS thin films can be effectively obtained via the vacuum-atmosphere sulfurization of Cu2SnS3/ZnS stacked sulfide layers. 相似文献
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Šljivić-Ivanović Marija Jelić Ivana Dimović Slavko Antonijević Dragi Jović Mihajlo Mraković Ana Smičiklas Ivana 《Clean Technologies and Environmental Policy》2018,20(6):1343-1354
Clean Technologies and Environmental Policy - In this study, the applicability of waste concrete as a sorbent material for the liquid radioactive waste management was considered. The sample was... 相似文献
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Z. Jovanović I. Pašti A. Kalijadis M. Laušević S. Mentus Z. Laušević 《Materials Letters》2011,65(17-18):2655-2657
We report a particular method of Pt/glassy carbon (GC) surface formation, based on a 15 keV H+/? ion beam irradiation of thin H2PtCl6 × nH2O layer placed over the GC surface. Hydrogen-ion beam irradiation provided an excellent adherence of Pt deposit, unlike to any other Pt-deposition method. Furthermore, the morphology and electrochemical activity of GC/Pt catalyst obtained at the fluence of 5 × 1017 cm? 2 was found to be sensitive to the sign of charge of hydrogen ions. The electrochemical activity of such obtained Pt/GC surface toward oxygen reduction and ethanol oxidation was compared with the activity of the Pt deposits obtained by other more common reduction procedures. 相似文献
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Gordana Ćirić-Marjanović Ivanka Holclajtner-Antunović Slavko Mentus Danica Bajuk-Bogdanović Dragana Ješić Dragan Manojlović Snežana Trifunović Jaroslav Stejskal 《Synthetic Metals》2010,160(13-14):1463-1473
Polyaniline (PANI) micro/nanostructures were synthesized by the external-template-free oxidative polymerization of aniline in aqueous solution of 12-tungstophosphoric acid (WPA), using ammonium peroxydisulfate (APS) as an oxidant and starting the oxidation of aniline from slightly acidic media (pH 5.4–5.9). The effect of the initial weight ratio of WPA to aniline on molecular structure, morphology, and physicochemical properties of polyaniline 12-tungstophosphate (PANI-WPA) was investigated by FTIR, Raman and inductively coupled plasma optical emission (ICP-OES) spectroscopies, elemental analysis, X-ray powder diffraction (XRPD), scanning and transmission electron microscopies (SEM and TEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and conductivity measurements. The morphological change of polymerization products during a single polymerization process, from non-conducting submicro-/microspherical oligoaniline intermediates to semiconducting PANI-WPA consisted of self-assembled nanotubes and/or nanorods co-existing with submicro-/microspheres, has been revealed by SEM and TEM. The average diameter of nanorods in PANI-WPA samples decreased with increasing the initial WPA/aniline weight ratio. The incorporation of 12-tungstophosphate counter-ions into PANI matrix has been proved by FTIR, Raman and ICP-OES spectroscopies, TGA and DTA analysis. Electrical conductivity of PANI-WPA increased in the range (2.5–5.3) × 10?3 S cm?1 with the increase of the initial WPA/aniline weight ratio. The presence of branched structures and phenazine units besides the ordinary paramagnetic and diamagnetic emeraldine salt structural features in PANI-WPA was proved by FTIR and Raman spectroscopies. 相似文献