Selective removal of trace elements from the Baltic by suspended matter     

K Boström  J-O Burman  C Pontér  J Ingri 《Marine Chemistry》1981,10(4):335-354

Suspended matter was collected at 30 stations in the Baltic and Kattegatt, at the thermocline and at the bottom, and analysed for Na, Ca, Mg, Si, Ti, Al, Fe, Mn, Ba, Sr, Ni and V. The composition of the suspended matter varies considerably, but can be described as a mixture of: (1) 12–25% terrigenous detritus with much Si, Al, Ti and Fe; (2) 75–88% biological matter with much Ni, V and Ba; and (3) some Mn-oxyhydroxide.The annual efflux of water from the Baltic is about 460 km³, with a suspended load in the Baltic straits of ～1.2–3.6 mg ash material l^?1 These values imply that much Si, Ti, Al, Fe, Sr, Ni and V and particularly much Ba and Mn are lost from the Baltic in the suspended load.The average suspended matter is richer in Mn(5×), Ba(2.5×), Sr(4×) and V(1.8×) than permanently depositing Baltic sediments. These constituents are relatively enriched in pelagic deposits, i.e. it is likely that much Mn, Ba and V in deep-sea sediments derive from the continents via suspended transport. This conclusion is supported by the similarity between suspended matter and average Atlantic pelagic sediment.  相似文献   

A fast hybrid algorithm for exoplanetary transit searches     

A. Collier Cameron  D. Pollacco  R. A. Street  T. A. Lister  R. G. West  D. M. Wilson  F. Pont  D. J. Christian  W. I. Clarkson  B. Enoch  A. Evans  A. Fitzsimmons  C. A. Haswell  C. Hellier  S. T. Hodgkin  K. Horne  J. Irwin  S. R. Kane  F. P. Keenan  A. J. Norton  N. R. Parley  J. Osborne  R. Ryans  I. Skillen  P. J. Wheatley 《Monthly notices of the Royal Astronomical Society》2006,373(2):799-810

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Poly-aromatic hydrocarbon (PAH) inputs from the Rhône River to the Mediterranean Sea in relation with the hydrological cycle: impact of floods     

Sicre MA  Fernandes MB  Pont D 《Marine pollution bulletin》2008,56(11):1935-1942

The concentrations of dissolved and particulate polycyclic aromatic hydrocarbons (PAHs) were monitored in waters of the Rhône River (France) every fortnight for a full calendar year, from June 1994 to May 1995. All flood events occurring over the course of the experiment were sampled at higher frequency to better quantify the impact of these extreme hydrological episodes on the annual export of PAHs to the Mediterranean Sea. This time-series indicates that more than 90% of the annual load of particulate PAHs is transported during flood episodes, with 77% discharged during the course of only one extreme flood event occurring in November 1994. During these intense events, riverine particles are depleted in PAHs while at low river discharge particles are PAH-enriched. Dissolved PAHs were less variable and less abundant than adsorbed PAHs, consistently with the low solubility of these compounds.  相似文献   

Local Stars as Tracers of Galactic Evolution     

B. Nordström  J. Andersen  E.H. Olsen  R. Fux  M. Mayor  N. Mowlavi  F. Pont 《Astrophysics and Space Science》1999,265(1-4):235-241

We describe the overall properties of a new catalogue of metallicities, ages, and galactic orbits for a large, complete sample of F and G dwarfs in the solar neighbourhood. Based on a magnitude-limited sample of ∼ 14000 stars, it is volume-complete to ∼ 40 pc. Together with the astrophysical parameters of direct relevance to models of the evolution of the disk, it will contain the basic photometric, astrometric, and radial velocity data from which they are derived. Information on duplicity is also included. The full exploitation of the data will require a lengthy analysis, in particular to assess the degree of completeness of subsamples of stars of different population types. An early result on the effects of diffusion of galactic orbits in the disk – essential for understanding the scatter in the age-metallicity diagram and estimating the birth radius of stars – is briefly illustrated. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Pervasive shock melting at >65 GPa in a Martian basalt,the shergottite Northwest Africa 14672     

R. H. Hewins  H. Leroux  D. Jacob  S. Pont  O. Beyssac  V. Malarewicz  J.-P. Lorand  P.-M. Zanetta  B. Zanda 《Meteoritics & planetary science》2024,59(4):640-669

Shergottites have provided abundant information on the volcanic and impact history of Mars. Northwest Africa (NWA) 14672 contributes to both of these aspects. It is a vesicular ophitic depleted olivine–phyric shergottite, with average plagioclase An₆₁Ab₃₉Or_0.2. It is highly ferroan, with pigeonite compositions En_49-25Fs_41-61Wo_10-14 like those of basaltic shergottites, for example, NWA 12335. Olivine (Fo_53-15) has discrete ferroan overgrowths, more ferroan when in contact with plagioclase than when enclosed by pyroxene. The pyroxene (a continuum of augite, subcalcic augite, and pigeonite) is patchy, with ragged “cores” enveloped or invaded by ferroan pyroxene. Magma mixing may be responsible for capture of olivine and formation of pyroxene mantles. The plagioclase is maskelynite-like in appearance, but the original laths were (congruently) melted and the melt partly crystallized as fine dendrites. Most of the 14% vesicles occur within plagioclase. Olivine, pyroxene, and ilmenite occur in part as fine aggregates crystallized after congruent melting with limited subsequent liquid mixing. There are two fine-grained melt components, barred plagioclase with interstitial Fe-bearing phases, and glass with olivine dendrites, derived by melting of mainly plagioclase and mainly pyroxene, respectively. Rare silica particles contain coesite and/or quartz, and silica glass. The rock has experienced >50% melting, compatible with peak pressure >~65 GPa. It is the most highly shocked shergottite so far, at shock stage S6/7. It may belong to the group of depleted shergottites ejected at ~1 Myr from Tooting Crater.  相似文献   

From discrete to continuum modelling of boundary value problems in geomechanics: An integrated FEM-DEM approach     

Jacques Desrues  Albert Argilaga  Denis Caillerie  Gaël Combe  Trung Kiên Nguyen  Vincent Richefeu  Stefano Dal Pont 《国际地质力学数值与分析法杂志》2019,43(5):919-955

Double-scale numerical methods constitute an effective tool for simultaneously representing the complex nature of geomaterials and treating real-scale engineering problems such as a tunnel excavation or a pressuremetre at a reasonable numerical cost. This paper presents an approach coupling discrete elements (DEM) at the microscale with finite elements (FEM) at the macroscale. In this approach, a DEM-based numerical constitutive law is embedded into a standard FEM formulation. In this regard, an exhaustive discussion is presented on how a 2D/3D granular assembly can be used to generate, step by step along the overall computation process, a consistent Numerically Homogenised Law. The paper also focuses on some recent developments including a comprehensive discussion of the efficiency of Newton-like operators, the introduction of a regularisation technique at the macroscale by means of a second gradient framework, and the development of parallelisation techniques to alleviate the computational cost of the proposed approach. Some real-scale problems taking into account the material spatial variability are illustrated, proving the numerical efficiency of the proposed approach and the benefit of a particle-based strategy.  相似文献   

The effect of red noise on planetary transit detection     

Frédéric Pont  Shay Zucker †  Didier Queloz 《Monthly notices of the Royal Astronomical Society》2006,373(1):231-242

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Opaque minerals,magnetic properties,and paleomagnetism of the Tissint Martian meteorite     

Jérôme Gattacceca  Roger H. Hewins  Jean‐Pierre Lorand  Pierre Rochette  France Lagroix  Cécile Cournède  Minoru Uehara  Sylvain Pont  Violaine Sautter  Rosa. B. Scorzelli  Chrystel Hombourger  Pablo Munayco  Brigitte Zanda  Hasnaa Chennaoui  Ludovic Ferrière 《Meteoritics & planetary science》2013,48(10):1919-1936

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A three‐dimensional staggered finite element approach for random parametric modeling of thermo‐hygral coupled phenomena in porous media     

F. Meftah  S. Dal Pont  B. A. Schrefler 《国际地质力学数值与分析法杂志》2012,36(5):574-596

The aim of this paper is to present a three‐dimensional (3D) finite element modeling of heat and mass transfer phenomena in partially saturated open porous media with random fields of material properties. Randomness leads to transfer processes within the porous medium that naturally need a full 3D modeling for any quantitative assessment of these processes. Nevertheless, the counterpart of 3D modeling is a significant increase in computations cost. Therefore, a staggered solution strategy is adopted which permits to solve the equations sequentially. This appropriate partitioning reduces the size of the discretized problem to be solved at each time step. It is based on a specific iterative algorithm to account for the interaction between all the transfer processes. Accordingly, a suitable linearization of mass convective boundary conditions, consistent with the staggered algorithm, is also derived. After some validation tests, the 3D numerical model is used for studying the drying process of a cementitious material with regard to its intrinsic permeability randomness. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

New continuous strain‐based description of concrete's damage‐permeability coupling          下载免费PDF全文

D. E.‐M. Bouhjiti  M. Ezzedine El Dandachy  F. Dufour  S. Dal Pont  M. Briffaut  J. Baroth  B. Masson 《国际地质力学数值与分析法杂志》2018,42(14):1671-1697

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