Multipath analysis of code measurements for BeiDou geostationary satellites   总被引：7，自引：2，他引：5  

Guangxing Wang  Kees de Jong  Qile Zhao  Zhigang Hu  Jing Guo 《GPS Solutions》2015,19(1):129-139

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Mapping of the Disc Structure of the Neutron Star X-ray Binary X1822-371     

O. Giannakis  E. T. Harlaftis  P. G. Niarchos  S. Kitsionas  H. Barwig  M. Still  R. G. M. Rutten 《Astrophysics and Space Science》2006,304(1-4):321-322

We report the results of simultaneous optical/X-ray observations of X1822-371 at 0.1 second time resolution. The preliminary analysis finds no correlation between the optical/X-ray light curves. We aim to constrain the vertical structure and radius of the accretion disc.Deceased Feb. 13, 2005  相似文献   

Spectral lines from photosphere to chromosphere,observed during the March 1970 eclipse; A first comparison with theory     

J. Houtgast  O. Namba  R. J. Rutten  J. W. Wijbenga 《Solar physics》1971,21(2):281-285

A brief report is presented on observations of line profile variations in the transition region from the photosphere to the chromosphere, based on high-resolution eclipse spectrograms. We also show some computations for several lines whose behaviour agrees in general with the observations.  相似文献   

Balancing exploitation and conservation of the eastern Scotian Shelf ecosystem: application of a 4D ecosystem exploitation index     

Bundy  Alida; Fanning  Paul; Zwanenburg  Kees C.T. 《ICES Journal of Marine Science》2005,62(3):503-510

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Alte Land- und Meeresverbindungen in West-Indien und Zentralamerika     

L. Rutten 《International Journal of Earth Sciences》1935,26(1-2):65-94

Ohne ZusammenfassungAusführlicher in holländischer Sprache in Tijdschr. Kon. Ned. Aardr. Genootsch. 1934, S. 551–600, erschienen.  相似文献   

An ELLAM approximation for advective–dispersive transport with nonlinear sorption     

Matthew W. Farthing  Christopher E. Kees  Thomas F. Russell  Cass T. Miller 《Advances in water resources》2006

We consider an Eulerian–Lagrangian localized adjoint method (ELLAM) applied to nonlinear model equations governing solute transport and sorption in porous media. Solute transport in the aqueous phase is modeled by standard advection and hydrodynamic dispersion processes, while sorption is modeled with a nonlinear local-equilibrium model. We present our implementation of finite volume ELLAM (FV-ELLAM) and finite element (FE-ELLAM) discretizations to the reactive transport model and evaluate their performance for several test problems containing self-sharpening fronts.  相似文献   

Wavefield extrapolation and amplitude-variation-with-angle migration in highly discontinuous media   总被引：4，自引：0，他引：4  

Jianfeng Zhang  Kees Wapenaar 《Geophysical Journal International》2003,155(1):327-339

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Versatile Two-Level Schwarz Preconditioners for Multiphase Flow     

C.E. Kees  C.T. Miller  E.W. Jenkins  C.T. Kelley 《Computational Geosciences》2003,7(2):91-114

Numerically modeling groundwater flow on finely discretized two- and three-dimensional domains requires solution algorithms appropriate for distributed memory multiprocessor architectures. Multilevel and domain decomposition algorithms are appropriate for preconditioning or solving linear systems in parallel and have, therefore, been applied to linear models for saturated groundwater flow. These algorithms have also been incorporated into more complex nonlinear multiphase flow models in the context of a linearization procedure such as Newton's method. In this work, we study a class of parallel preconditioners based on two-level Schwarz domain decomposition applied in a nonlinear two-phase flow numerical model. The restriction and interpolation operators are based on an aggregation approach that has a straightforward implementation for a variety of applications arising in subsurface modeling: structured and unstructured discretizations, finite elements and finite differences, and multicomponent model equations. We present model formulations, results from numerical experiments, and a comparison of a standard one-level Schwarz method to three two-level aggregation-based methods.  相似文献   

The stream impact region in the disc of WZ Sge     

H. C. Spruit  & R. G. M. Rutten 《Monthly notices of the Royal Astronomical Society》1998,299(3):768-776

We report the observation of new features in the spectrum of the cataclysmic variable WZ Sge. The disc eclipse is seen as a well-defined structure in the Hα line. From phases 0.25 to 0.5 an absorption feature of the same shape as the emission S wave is seen in this line, but redshifted by ∼ 200 km s⁻¹. Two possible interpretations of this feature are given, both of which imply that it originates at the impact point of the stream on the disc edge. In addition, evidence is found for substructure in the velocity map of the spot. Emission from line-emitting post-shock material, extending to about 60° downstream from the continuum hotspot, is seen in the Doppler map in the form of a tail extending from the hotspot. A theoretical estimate shows that such a tail is to be expected as a consequence of the post-impact hydrodynamics of the stream. A new determination of the system parameters is made. They agree with those of Gilliland et al.; in particular, the data support a high primary mass. The variation of Hα surface brightness with distance from the primary is flatter, in the inner regions, than the r ^−1.5 dependence found by Horne for other cataclysmic variables in quiescence.  相似文献   

Inexact Newton methods and the method of lines for solving Richards' equation in two space dimensions     

Michael D. Tocci  C.T. Kelley  Cass T. Miller  Christopher E. Kees 《Computational Geosciences》1998,2(4):291-309

Richards' equation (RE) is often used to model flow in unsaturated porous media. This model captures physical effects, such as sharp fronts in fluid pressures and saturations, which are present in more complex models of multiphase flow. The numerical solution of RE is difficult not only because of these physical effects but also because of the mathematical problems that arise in dealing with the nonlinearities. The method of lines has been shown to be very effective for solving RE in one space dimension. When solving RE in two space dimensions, direct methods for solving the linearized problem for the Newton step are impractical. In this work, we show how the method of lines and Newton-iterative methods, which solve linear equations with iterative methods, can be applied to RE in two space dimensions. We present theoretical results on convergence and use that theory to design an adaptive method for computation of the linear tolerance. Numerical results show the method to be effective and robust compared with an existing approach.  相似文献