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    Wyświetlanie 1-5 z 5
    Tytuł:
    Spatial distribution and settling velocity of heavy particles in synthetic turbulent fields
    Autorzy:
    Łuniewski, M.
    Pozorski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/175528.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    two-phase flow
    heavy particles
    turbulent dispersion
    Opis:
    We analyse numerically the motion of small inertial particles, subject to gravity, in two simple velocity fields: two-dimensional cellular flow, and a three-dimensional flow being the superposition of random Fourier velocity modes. The latter, also known as the kinematic simulation or synthetic turbulence, has often been applied in various studies, including those aiming to predict particle dispersion. The interplay of the particle inertia and the acceleration of gravity has non-trivial consequences for trajectories of particles and their spatial distribution, known as a preferential concentration. Also, we compute the average settling velocity of particles in function of their inertia and the number of fluid velocity modes used in simulations. The present paper aims to study these efects, as the synthetic turbulence represents an interesting option for subfilter modeling in particle-laden large-eddy simulation.
    Źródło:
    Transactions of the Institute of Fluid-Flow Machinery; 2017, 135; 87-100
    0079-3205
    Pojawia się w:
    Transactions of the Institute of Fluid-Flow Machinery
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of LiF : Mg,Cu,P (MCP-N) thermoluminescent detectors (TLD) for experimental verification of radial dose distribution models
    Autorzy:
    Gieszczyk, W.
    Olko, P.
    Bilski, P.
    Grzanka, L.
    Obryk, B.
    Horwacik, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/146734.pdf
    Data publikacji:
    2012
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    heavy charged particles
    LiF:Mg,Cu,P (MCP-N)
    radial dose distribution
    thermoluminescence
    unfolding
    Opis:
    In track structure theory, the radial distribution of dose, D(r), around an ion track plays a fundamental role in predicting the response of biological systems and physical detectors after a dose (or fluence) of ions. According to the formulations of D(r), the local dose at radial distances below 1 nm can reach values as high as 106 Gy. We propose a new method of verifying experimentally the radial dose distribution around alfa-particle tracks, using LiF:Mg,Cu,P (MCP-N) thermoluminescent detectors (TLD) which are able to measure gamma-ray doses in the kGy range via evaluation of their high-temperature TL glow peak structure over the temperature range of 350–550 centigrade. MCP-N detectors were irradiated with Am-241 alfa-particles at fluences ranging from 107 to 1011 particles/cm2, and by Co-60 gamma-ray doses ranging from several Gy up to the MGy. A number N of individual high-temperature TL peaks were analysed in the obtained glow curves by deconvolution, using the GlowFit code. For each of these peaks, an equation relating the intensity, A, of the TL signal obtained after alfa-particle irradiation and after gamma-ray doses, via the dose-frequency function, f alfa(D), was written in the form: A i alfa = integral A i gamma(D)x f alfa (D)dD, i 1,.., N. Using this set of N equations, where A alfa i and A gamma i(D) were known (measured), the single unknown function f alfa(D) was unfolded and converted to D(r). Parametric unfolding and the SAND-II iterative code were applied. While we were able to confirm the 1/r2 dependence of D(r) in agreement with D(r) expressions, we were unable to conclusively evaluate the dependence of D(r) at intermediate ranges of radial distance r. This preliminary result of our unique experimental approach to determine the radial dose distribution around the path of heavy charged particles in LiF detectors, requires further development.
    Źródło:
    Nukleonika; 2012, 57, 4; 507-512
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Alternative size and lifetime measurements for RHIC
    Autorzy:
    Pratt, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/147468.pdf
    Data publikacji:
    2004
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    interferometry
    identical particles
    heavy ion collision
    correlations
    Opis:
    Two-particle correlations based on the interference of identical particles have provided the chief means for determining the shape and lifetime of sources in relativistic heavy ion collisions (RHIC). Here, strong and Coulomb induced correlations are shown to provide similar information.
    Źródło:
    Nukleonika; 2004, 49,suppl.2; 61-65
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Freeze-out and anisotropic flow in microscopic models
    Autorzy:
    Bravina, L.
    Tywoniuk, K.
    Zabrodin, E.
    Burau, G.
    Bleibel, J.
    Fuchs, Ch.
    Faessler, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/148598.pdf
    Data publikacji:
    2006
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    ultrarelativistic heavy-ion collisions
    elliptic flow
    freeze-out of particles
    Monte-Carlo quark-gluon string model
    Opis:
    It appears that in microscopic calculations hadrons are continuously emitted from the whole reaction volume. Different species decouple at different times. At RHIC energies significant fractions of both mesons and baryons are emitted from the surface region within the first two fm/c. The hadrons contribute differently to the formation and evolution of the anisotropic flow, which can be decomposed into three components: (i) flow created by hadrons emitted from the surface at the onset of the collision; (ii) flow produced by jets; (iii) hydrodynamic flow. Due to these features, e.g., the elliptic flows of mesons and baryons have different transverse momentum dependences. Comparison with experimental data reveals that centrality, rapidity, and transverse momentum dependences of the anisotropic flow are reproduced, at least qualitatively, by the microscopic models.
    Źródło:
    Nukleonika; 2006, 51,suppl.3; 3-6
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Masowy rozkład pierwiastków w próbkach pyłu zawieszonego pobranych w obszarze tła miejskiego: wyniki ośmiomiesięcznych badań w Zabrzu
    Mass Size Distribution of PM-bound Elements at an Urban Background Site: Results of an Eight-month Study in Zabrze
    Autorzy:
    Rogula-Kozłowska, W.
    Klejnowski, K.
    Rogula-Kopiec, P.
    Błaszczak, B.
    Mathews, B.
    Szopa, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1819065.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Koszalińska. Wydawnictwo Uczelniane
    Tematy:
    rozkład pierwiastków
    próbki pyłu
    particulate air-pollution
    trace elements
    source identification
    atmospheric aerosol
    fine particles
    heavy metals
    source apportionment
    Opis:
    The analysis of elemental composition of ambient dust can help not only evaluate the environmental and health effects due to the air pollution but also identify emission sources. However, the whole number of projects and studies on concentrations and elemental composition of ambient (especially fine) dust hardly concern these issues in Eastern Europe. Neither is the chemical (and elemental) composition of the submicron ambient dust in Poland well recognized. There is also a shortage of data from long-term and parallel studies of the elemental composition of separate dust fractions. In the heavily polluted areas, the elemental composition of atmospheric aerosol and the dependence of elemental composition of particles on their size can appear essential for analyzing the toxicity of dust and its environmental effects. This study presents the results of determination and comparison of the elemental composition of four fractions of ambient dust in Zabrze (Poland), an urban area typical of the exposure of the Upper-Silesian Agglomeration population to the polluted air. The samples of the four dust fractions (fine: ≤1 µm – PM1, 1–2.5 µm – PM1-2.5, coarse: 2.5–10 µm – PM2.5-10, and 10–40 µm – PM10-40,) were collected during eight months (January–August 2009) with the use of a DEKATI-PM10 cascade impactor. All the dust samples (204 samples) were analyzed using a PANalytical Epsilon 5 spectrometer (EDXRF – energy dispersive X-Ray fluorescence spectroscopy). The minimum, maximum and average concentrations, for winter (January–April, heating season) and summer (May–August, non-heating season), of 38 elements from each of the four examined dust fractions were calculated. The influence of anthropogenic sources on the ambient concentrations of elements from each dust fraction was determined by analyzing the enrichment factors (EF). The strength of linear relationships (Pearson’s linear correlation coefficients) between each pair of elements was determined separately for fine and coarse dust. The highest ambient concentrations were assumed by two nonmetals – sulfur and chlorine; their concentrations were significantly lower in summer than in winter. Both sulfur and chlorine were mainly bound onto the finest particles. Their share in the coarse dust, even in summer, was small. They came from anthropogenic sources. Ambient, typical crustal, Si, Al, Fe, Mg, K, Ca, Ti, Sr, Rb in Zabrze came from natural sources regardless of the fraction they were bound to. Small seasonal variations in ambient concentrations of these elements or some of the concentrations higher in summer than in winter confirmed the fact. A significant portion of the mass of the crustal elements, especially of Al, Si and Fe, was concentrated in the coarse fractions. However, the mass distribution among the dust fractions indicates some of them (K, Ca, Mg, Rb, Sr) as coming partly from anthropogenic sources. It particularly concerns their part bound to fine dust in winter. The mass contribution of crustal matter to ambient dust was about 6.8 in winter and 9.7% in summer; the contribution to PM1 was half of it. Almost all remaining 27 elements (except for Mn, Zn, Ge, Sb, La) had the ambient concentrations not greater than 100 ng m-3, usually higher in winter. The average mass shares of each of these 27 elements in PM1, PM1-2.5, PM2.5-10, and PM10-40, were different and depended on the season of a year. Co, Cu, Zn, Pb and As were cumulated mostly in fine dust, while V, Mn, Co, Cr, Ni, Ag, Cd and Ba in coarse dust. The former, in fine dust, were assumed to be rather of anthropogenic origin and closely associated with combustion. The later originated partly from combustion (especially in winter) but their greater part was secondary and came from road dust. The largest contributors to the mass of the elements in fine dust in Zabrze are domestic furnaces and car engines, i.e. combustion of fossil fuels, biomass, and waste. The possible effect of industrial sources was also identified. The elemental composition of coarse dust is due to re-suspension of soil and road dust, and to a lesser extent, to municipal emission.
    Źródło:
    Rocznik Ochrona Środowiska; 2013, Tom 15, cz. 2; 1022-1040
    1506-218X
    Pojawia się w:
    Rocznik Ochrona Środowiska
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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