Highly gravity-driven flow of a NAPL in water-saturated porous media using the discontinuous Galerkin finite-element method with a generalised Godunov scheme     

Lauriane Schneider  Raphaël di Chiara Roupert  Gerhard Schäfer  Philippe Helluy 《Computational Geosciences》2015,19(4):855-876

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Estimating the modal mineralogy of eucrite and diogenite meteorites using visible–near infrared reflectance spectroscopy          下载免费PDF全文

Shuai Li  Ralph E. Milliken 《Meteoritics & planetary science》2015,50(11):1821-1850

Reliable quantitative mapping of minerals exposed on Vesta's surface is crucial for understanding the crustal composition, petrologic evolution, and surface modification of the howardite, eucrite, and diogenite (HED) parent body. However, mineral abundance estimates derived from visible–near infrared (VIS–NIR) reflectance spectra are complicated by multiple scattering, particle size, and nonlinear mixing effects. Radiative transfer models can be employed to accommodate these issues, and here we assess the utility of such models to accurately and efficiently determine modal mineralogy for a suite of eucrite and olivine‐bearing (harzburgitic) diogenite meteorites. Hapke and Shkuratov radiative transfer models were implemented to simultaneously estimate mineral abundances and particle size from VIS–NIR reflectance spectra of these samples. The models were tested and compared for laboratory‐made binary (pyroxene–plagioclase) and ternary mixtures (pyroxene–olivine–plagioclase) as well as eucrite and diogenite meteorite samples. Results for both models show that the derived mineral abundances are commonly within 5–10% of modal values and the estimated particle sizes are within the expected ranges. Results for the Hapke model suggest a lower detection limit for olivine in HEDs when compared with the Shkuratov model (5% versus 15%). Our current implementation yields lower uncertainties in mineral abundance (commonly <5%) for the Hapke model, though both models have an advantage over typically used parameters such as band depth, position, and shape in that they provide quantitative information on mineral abundance and particle size. These results indicate that both the Hapke and Shkuratov models may be applied to Dawn VIR data in a computationally efficient manner to quantify the spatial distribution of pyroxene, plagioclase, and olivine on the surface of Vesta.  相似文献   

New low surface brightness dwarf galaxies detected around nearby spirals     

I. D. Karachentsev  P. Riepe  T. Zilch  M. Blauensteiner  M. Elvov  P. Hochleitner  B. Hubl  G. Kerschhuber  S. Küppers  F. Neyer  R. Pölzl  P. Remmel  O. Schneider  R. Sparenberg  U. Trulson  G. Willems  H. Ziegler 《Astrophysical Bulletin》2015,70(4):379-391

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Geometric consistency for regression model estimation and testing in climatology and meteorology     

Raymond K.W. Wong  C. Schneider  Paul W. Mielke Jr 《大气与海洋》2013,51(3):508-520

Abstract

The effects of outliers on linear regression are examined. The sensitivity of classical least‐squares (LS) procedures to outliers is shown to be associated with the geometric inconsistency between the data space and the analysis space. This is illustrated for both estimation and inference. A geometrically consistent procedure based on the Euclidean distance is proposed. This procedure involves the least absolute deviation (LAD) regression and a new permutation test for matched pairs (PTMP). Comparisons made with LS techniques demonstrate that the proposed procedure is more resistant to the existence of outliers in the data set and leads to more intuitive results. Applications and illustrations using meteorological and climatological data are also discussed.  相似文献   

An FDTD method for analysis of scattering from rough fluid-fluidinterfaces     

Hastings  F.D. Schneider  J.B. Broschat  S.L. Thorsos  E.I. 《Oceanic Engineering, IEEE Journal of》2001,26(1):94-101

A finite-difference time-domain (FDTD) method for scattering by one-dimensional, rough fluid-fluid interfaces is presented, modifications to the traditional FDTD algorithm are implemented which yield greater accuracy at lower computational cost. These modifications include use of a conformal technique, in which the grid conforms locally to the interface, and a correction for the numerical dispersion inherent to the FDTD algorithm, Numerical results are presented for fluid-fluid cases modeling water-sediment interfaces. Two different roughness spectra, the single-scale Gaussian roughness spectrum and a multiscale modified power-law spectrum, are used. The Gaussian results are calculated as a function of the dimensionless parameters kh and kl, where k is the wavenumber in water, h is the rms surface height, and l is the surface correlation length. For the modified power-law spectrum, statistical parameters consistent with an insonification frequency of 7.5 kHz are used. Results are compared with those obtained using an integral equation technique both for scattering from single-surface realizations and for Monte Carlo averages of scattering from an ensemble of surface realizations. Scattering strengths are calculated as a function of scattering angle for an incident angle of 70° (20° grazing). The results agree well over all scattering angles for the cases examined  相似文献   

Controlling the collimation and rotation of hydromagnetic disc winds     

Ralph E. Pudritz  Conrad S. Rogers  Rachid Ouyed 《Monthly notices of the Royal Astronomical Society》2006,365(4):1131-1148

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Panchromatic properties of 99 000 galaxies detected by SDSS, and (some by) ROSAT, GALEX, 2MASS, IRAS, GB6, FIRST, NVSS and WENSS surveys     

M. Obri&#;  &#;. Ivezi&#;  P. N. Best  R. H. Lupton  C. Tremonti  J. Brinchmann  M. A. Agüeros  G. R. Knapp  J. E. Gunn  C. M. Rockosi  D. Schlegel  D. Finkbeiner  M. Ga&#;e&#;a  V. Smol&#;i&#;  S. F. Anderson  W. Voges  M. Juri&#;  R. J. Siverd  W. Steinhardt  A. S. Jagoda  M. R. Blanton  D. P. Schneider 《Monthly notices of the Royal Astronomical Society》2006,370(4):1677-1698

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Thermal interactions of the Huygens probe with the Titan environment: Constraint on near-surface wind     

Ralph D. Lorenz 《Icarus》2006,182(2):559-566

The Huygens probe lost heat to its cold environment during its descent through Titan's atmosphere and after landing. Here I report measurements of the probe's thermal behavior and comparison with ground tests (1) to provide a context for other scientific investigations, such as the release of volatiles from the landing site, and (2) to place constraints on Titan environmental parameters directly, such as the thermal conductivity of the surface material and the strength of winds at the surface. Near-surface winds are constrained to be less than 0.2 m s⁻¹, and probably much less.  相似文献   

Supersonic turbulence, filamentary accretion and the rapid assembly of massive stars and discs     

Robi Banerjee  Ralph E. Pudritz  Dave W. Anderson 《Monthly notices of the Royal Astronomical Society》2006,373(3):1091-1106

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Early enrichment of quasars by the first stars     

A. Venkatesan  R. Schneider †  A. Ferrara 《Monthly notices of the Royal Astronomical Society》2004,349(3):L43-L48

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