Évolution temporelle et architecture interne d'un banc sableux estuarien : la Longe de Boyard (littoral atlantique,France)     

Éric Chaumillon  Hervé Gillet  Nicolas Weber  Michel Tesson 《Comptes Rendus Geoscience》2002,334(2):119-126

The evolution and the internal architecture of an estuary type sand ridge has been studied with a set of bathymetric data recorded during the last two centuries and with a dense grid of recent very high resolution seismic profiles. Bathymetric data of the so-called, Longe de Boyard sand ridge, displays sand losts due to wave and tide erosion. Internal geometry, through seismic profile analysis, indicates two main phases of deposition recording both, a recent high energy environment and an older low energy one, respectively. Such an evolution is believed to record changes in sedimentation processes mainly related to the end of the Holocene transgression (8 000–5 000 yr BP). To cite this article: É. Chaumillon et al., C. R. Geoscience 334 (2002) 119–126.  相似文献   

Virtual MHD Jets on Grids     

Thibaut Lery  CÉline Combet  Gareth Murphy  Luke O. C. Drury 《Astrophysics and Space Science》2005,298(1-2):375-378

As network performance has outpaced computational power and storage capacity, a new paradigm has evolved to enable the sharing of geographically distributed resources. This paradigm is known as Grid computing and aims to offer access to distributed resource irrespective of their physical location. Many national, European and international projects have been launched during the last years trying to explore the Grid and to change the way we are doing our everyday work. In Ireland, we have started the CosmoGrid project that is a collaborative project aimed to provide high performance super-computing environments. This will help to address complex problems such as magnetohydrodynamic outflows and jets in order to model and numerically simulate them. Indeed, the numerical modeling of plasma jets requires massive computations, due to the wide range of spatial-temporal scales involved. We present here the first jet simulations and their corresponding models that could help to understand results from laboratory experiments.  相似文献   

Macroseismic effects related to strong ground motion: a study of the South Iceland earthquakes in June 2000   总被引：1，自引：1，他引：1  

R. Sigbjörnsson  S. Ólafsson  J. Th. Snæbjörnsson 《Bulletin of Earthquake Engineering》2007,5(4):591-608

The impact of the June 2000 South Iceland earthquakes has been assessed applying data collected in field surveys and strong-motion recordings from the Icelandic Strong-Motion Network. The areas within approximately 20 km of the causative faults suffered considerable damage, including transportation and utility systems as well as buildings, both with regard to structure and inventories. Ground subsidence and dislocations were significant in the near-fault zone. Aftershocks and permanent displacements of building foundations resulted in progressive structural damage. By introducing holistic measures derived from the acceleration data, a fair correlation was achieved between the obtained earthquake intensities and the recorded accelerations. The measures adopted were square root of the sum of the squares (SRSS) values of peak ground acceleration (PGA) and the trace of the Arias intensity tensor. It was found that the overall attenuation tended to be more rapid than reflected by common strong-motion models reported in the literature. There is no simple explanation for this behaviour but it is reasonable to suggest that it can be partly attributed to the heterogeneous and fractured crust that is characteristic of Icelandic geology.  相似文献   

From the green color of eskolaite to the red color of ruby: an X-ray absorption spectroscopy study     

Émilie Gaudry  Philippe Sainctavit  Farid Juillot  Federica Bondioli  Philippe Ohresser  Isabelle Letard 《Physics and Chemistry of Minerals》2006,32(10):710-720

The best known cause for colors in insulating minerals is due to transition metal ions as impurities. As an example, Cr³⁺ is responsible for the red color of ruby (α-Al₂O₃:Cr³⁺) and the green color of eskolaite (α-Cr₂O₃). Using X-ray absorption measurements, we connect the colors of the Cr _x Al_2−x O₃ series with the structural and electronic local environment around Cr. UV–VIS electronic parameters, such as the crystal field and the Racah parameter B, are related to those deduced from the analysis of the isotropic and XMCD spectra at the Cr L_2,3-edges in Cr_0.07Al_1.93O₃ and eskolaite. The Cr–O bond lengths are extracted by EXAFS at the Cr K-edge in the whole Cr _x Al_2−x O₃ (0.07≤x< 2) solid solution series. The variation of the mean Cr–O distance between Cr_0.07Al_1.93O₃ and α-Cr₂O₃ is evaluated to be 0.01₅ Å (≈1%). The variation of the crystal field in the Cr _x Al_2−x O₃ series is discussed in relation with the variation of the averaged Cr–O distances.  相似文献   

Observations of a solar radio burst on September 27, 1969     

Haruo Tanaka  Shinzo Énomé 《Solar physics》1971,17(2):408-411

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An asymptotic solution for the Trojan case of the plane elliptic restricted problem of three bodies     

Bálint Érdi 《Celestial Mechanics and Dynamical Astronomy》1977,15(3):367-383

The planar motion of a Trojan asteroid is considered within the framework of the elliptic restricted three-body problem. The solution is derived asymptotically to second order taking the square root of the Jupiter-Sun mass ratio and the orbital eccentricity of Jupiter as first order quantities. The results are given in explicit form for the coordinates as functions of the true anomaly of Jupiter including both short and long periodic terms resulting from the orbital accentricity of Jupiter.  相似文献   

Convection in the envelopes of main sequence A-F stars     

É. Érgma 《Astrophysics》1971,7(4):363-365

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The three-dimensional motion of Trojan asteroids     

Bálint Érdi 《Celestial Mechanics and Dynamical Astronomy》1978,18(2):141-161

The problem is considered within the framework of the elliptic restricted three-body problem. The asymptotic solution is derived by a three-variable expansion procedure. The variables of the expansion represent three time-scales of the asteroids: the revolution around the Sun, the libration around the triangular Lagrangian pointsL ₄,L ₅, and the motion of the perihelion. The solution is obtained completely in the first order and partly in the second order. The results are given in explicit form for the coordinates as functions of the true anomaly of Jupiter. As an example for the perturbations of the orbital elements the main perturbations of the eccentricity, the perihelion longitude and the longitude of the ascending node are given. Conditions for the libration of the perihelion are also discussed.  相似文献   

Metallicity function of globular clusters     

A. M. Éigenson 《Astrophysics》1977,13(3):306-307

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Drumlin sedimentology in a hard‐bed,lowland setting,Connemara, western Ireland: implications for subglacial bedform generation in areas of sparse till cover          下载免费PDF全文

DAVID J. A. EVANS  DAVID H. ROBERTS  COLM Ó COFAIGH 《第四纪科学杂志》2015,30(6):537-557

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