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21.
The paper presents several sorting methods of γ-ray events which were implemented in the data acquisition, processing and visualization system, developed at the Institute of Physics of the Slovak Academy of Sciences. The sorting methods using various shapes of gates (conditions) are presented, including rectangular windows, polygons, gates defined by arithmetic functions, spherical, ellipsoidal and composed gates. The examples illustrating the use of these methods are presented as well. 相似文献
22.
Pressureless sintering of boron carbide ceramics containing 0-25 vol. % TiB2 phase, produced via an in-situ chemical reaction between B4C, TiO2, and elemental carbon, was studied in the isothermal and constant-heating-rate regimes. The presence of TiB2 results in a decrease in activation energy for sintering from 717 kJ/mol at 0 vol. % TiB2 to 266 kJ/mol at 25 vol. % TiB2. Ceramic bodies of B4C TiB2 particulate composites with relative densities of up to 99% were sintered without pressure at temperatures of 2050-2100°C. Grain boundary diffusion is the primary mechanism of TiB2 particle coarsening. TiB2 particle size is bimodal depending on whether the particle is confined within a B4C grain or located on the grain boundary. Densification behavior of the B4C TiB2 system is identical at different heating rates in the temperature range of 1800-2150°C. 相似文献
23.
One of the numerous challenges awaiting Serbia in the process of European integration is the increase in use of renewable sources of energy. The reason for such an increase is not merely a formal acceptance of European goals but the high energy import dependence, a relatively developed agricultural sector, with insufficiently exploited potentials of biomass, accompanied by an ever-growing awareness of the need for establishing long-lasting sustainable development. Serbia has a relatively undeveloped livestock sector which can absorb a limited portion of the biomass produced. Additionally, insufficient awareness on the part of farmers and the preconception of the low cost-effectiveness of biomass utilisation for the purpose of energy production are factors which, unsurprisingly, contribute to the current practice of burning the largest portion of the biomass produced on site, which is economically and ecologically unacceptable. This paper analyses the amounts of biomass available in Serbia and the prospects of its economically viable utilisation. The cost analysis conducted indicates that the energy obtained from small rectangular straw bales (the most widespread way of utilisation), is less costly by 28%, than the energy obtained from coal, whereas the energy obtained from round bales is cheaper by 34%. Sensitivity analysis has shown that the results obtained are relatively resistant to price changes in the most important inputs. The sensitivity is higher towards the efficiency of the machinery used; therefore, insistent efforts should be made for creating conditions where the introduction of more up-to-date technical solutions, already existing in developed countries, will become feasible. 相似文献
24.
Vladislav Dushin Valeriy Nikitin Yuri Philippov Nickolay Smirnov 《Microgravity science and technology》2008,20(3-4):155-160
The paper presents the results of investigating the instability of the displacement of viscous fluid by a less viscous one in two-dimensional and three-dimensional porous specimens. The effects of the three-dimensional phenomena on development of instability are revealed, in particular, the faster growth of 3D disturbances as compared with 2D ones, while 2D displacement integral parameters (such as the outflow of the displacing fluid) have much higher deviations than those parameters obtained in 3D modelling. This can be explained by much higher number of fingers in 3D cases of displacement reaching the outflow surface, and by the subsequent compensation of disturbances in the overall outflow. 相似文献
25.
Vladislav Sadykov Vladimir Sobyanin Natalia Mezentseva Zakhar Vostrikov Vladimir Pelipenko Sergey Tikhov Lyudmila Bobrova Julian R.H. Ross Vladimir Ulyanitskii 《Fuel》2010,89(6):1230-180
Active components comprised of fluorite-like Lnx(Ce0.5Zr0.5)1−xO2−y (Ln = La, Pr, Sm) and perovskite-like La0.8Pr0.2Mn0.2Cr0.8O3 mixed oxides and their composites with yttria-doped zirconia (YSZ) promoted by precious metals (Pt, Ru) and/or Ni were supported on several types of heat-conducting substrates (compressed Ni-Al foam, Fecralloy foil or gauze protected by corundum layer, Cr-Al-O microchannel cermets, titanium platelets protected by oxidic layer) as well as on honeycomb corundum monolithic substrate. These structured catalysts were tested in pilot-scale reactors in the reactions of steam reforming of methane, selective oxidation of decane and gasoline and steam/autothermal reforming of biofuels (ethanol, acetone, anisole, sunflower oil). Applied procedures of supporting nanocomposite active components on monolithic/structured substrates did not deteriorate their coking stability in real feeds with a small excess of oxidants, which was reflected in good middle-term (up to 200 h) performance stability promising for further up-scaling and long-term tests. Equilibrium yield of syngas at short contact times was achieved by partial oxidation of decane and gasoline without addition of steam usually required to prevent coking. For the first time possibility of successive transformation of biofuels (ethanol, acetone, anisole, sunflower oil) into syngas at short contact times on monolithic catalysts was demonstrated. This was provided by a proper combination of active component, thermal conducting monolithic substrates and unique evaporation/mixing unit used in this research. 相似文献
26.
Trace metals in Phragmites australis and Phalaris arundinacea growing in constructed and natural wetlands 总被引:1,自引:0,他引:1
Vymazal J Svehla J Kröpfelová L Chrastný V 《The Science of the total environment》2007,380(1-3):154-162
Constructed wetlands with horizontal subsurface flow (HF CWs) designed for treatment of municipal sewage have been monitored extensively with respect to removal of organics, suspended solids, nitrogen, phosphorus and bacteria. However, the information on the removal of various metals and metalloids in these systems is very limited. During the period 2002-2004 aboveground and belowground biomass of Phragmites australis (common reed) and Phalaris arundinacea (reed canarygrass) were sampled in three HF CWs in the Czech Republic. Concentrations of monitored elements in both aboveground and belowground plant tissues were similar to those found in plants growing in natural stands. The concentrations were much lower as compared to those found in plants growing in wetlands receiving acid mine drainage waters, waters from smelters or highway runoff. Concentrations decrease in the order of roots>rhizomes>leaves>stems. The leaf:stem concentration ratios were quite similar for all monitored elements ranging between 1.0 and 1.9. The root:leaf concentration ratio varied widely between 1.5 (Cu) and 54 (Cr) with a mean value of 20.0. Belowground/aboveground plant tissue concentration ratios varied from 2.2 (Cu) to 32 (Cr) with the average value of 9.9. 相似文献
27.
Hugo R. Fernandes Dilshat U. Tulyaganov Maria J. Pascual Vladislav V. Kharton Aleksey A. Yaremchenko José M.F. Ferreira 《Journal of the European Ceramic Society》2012,32(10):2283-2292
The effects of K2O content on sintering and crystallization of glass powder compacts in the Li2O–K2O–Al2O3–SiO2 system were investigated. Glasses featuring SiO2/Li2O molar ratios of 2.69–3.13, far beyond the lithium disilicate (LD-Li2Si2O5) stoichiometry, were produced by conventional melt-quenching technique. The sintering and crystallization behaviour of glass powders was explored using hot stage microscopy (HSM), scanning electron microscopy (SEM), differential thermal (DTA) and X-ray diffraction (XRD) analyses. Increasing K2O content at the expense of SiO2 was shown to lower the temperature of maximum shrinkage, eventually resulting in early densification of the glass-powder compacts. Lithium metasilicate was the main crystalline phase formed upon heat treating the glass powders with higher amounts of K2O. In contrast, lithium disilicate predominantly crystallized from the compositions with lower K2O contents resulting in strong glass–ceramics with high chemical and electrical resistance. The total content of K2O should be kept below 4.63 mol% for obtaining LD-based glass–ceramics. 相似文献
28.
29.
Svetlana Pavlova Tamara Kharlamova Vladislav Sadykov Tamara Krieger Vitaly Muzykantov Yulia Bespalko 《传热工程》2013,34(11-12):904-916
Mixed ionic?electronic conducting nanocomposites comprising complex oxides - perovskite (lanthanum-strontium nickelate-ferrite [LSFN]) and gadolinium-doped ceria (GDC) have been prepared via ultrasonic dispersion of nanocrystalline powders of LSFNx and GDC in organic solvent with addition of surfactant, followed by drying and sintering up to 1300°C. Their structural and surface properties have been studied by x-ray diffraction, ultraviolet–visible (UV-vis) electron spectroscopy, transmission electron microscopy with elemental analysis, and x-ray photoelectron spectroscopy. Results of impedance spectroscopy, oxygen isotope exchange, O2 temperature-programmed desorption, weight, and conductivity relaxation experiments have revealed a strong positive effect of perovskite?fluorite nanodomain interfaces in composite on the oxygen mobility and reactivity. Testing in wet H2/air feeds for a button-size cell with functionally graded LSFN0.4–GDC cathode layer supported on a thin YSZ layer covering Ni/YSZ cermet has demonstrated high and stable performance, promising for the practical application in the intermediate temperature range. 相似文献
30.
Vladimir Ivanovich Lysenko Sergey Bardakhanov Alexey Korchagin Nikolay Kuksanov Alexander Lavrukhin Rustam Salimov Sergey Fadeev Vladislav Cherepkov Mikhail Veis Andrey Nomoev 《Bulletin of Materials Science》2011,34(4):677-681
Electron-beam evaporation of various natural and industrial materials in the atmosphere of different gases at atmospheric
pressure can be used for the synthesis of nanosize powders. These powders are characterized by high purity and may exhibit
unusual properties. In particular, nanopowders of silicon dioxide and oxide (SiO2, SiO), magnesia (MgO), alumina (Al2O3), titania (TiO2), gadolinium oxide (Gd2O3), various metals (tantalum, molybdenum, nickel, aluminium, copper, silver), semiconductor (Si), nitrides (AlN, TiN), and
some other substances had been produced. The process of nanopowder synthesis is highly effective; in particular, the yield
of oxides can exceed ten kilograms per hour. 相似文献