An improved methodology for filling missing values in spatiotemporal climate data set     

Antti Sorjamaa  Amaury Lendasse  Yves Cornet  Eric Deleersnijder 《Computational Geosciences》2010,14(1):55-64

In this paper, an improved methodology for the determination of missing values in a spatiotemporal database is presented. This methodology performs denoising projection in order to accurately fill the missing values in the database. The improved methodology is called empirical orthogonal functions (EOF) pruning, and it is based on an original linear projection method called empirical orthogonal functions (EOF). The experiments demonstrate the performance of the improved methodology and present a comparison with the original EOF and with a widely used optimal interpolation method called objective analysis.  相似文献   

Physical properties of fault zones within a granite body: Example of the Soultz-sous-Forêts geothermal site     

Yves Géraud  Michel Rosener  Fabrice Surma  Joachim Place  Édouard Le Garzic  Marc Diraison 《Comptes Rendus Geoscience》2010,342(7-8):566-574

In EGS projects, fault zones are considered as the structures controlling deep flow at the reservoir scale. Using a large set of petrophysical properties (porosity, density, permeability, thermal conductivity [TC]) measured on cores collected along the EPS-1 borehole, a model of fault zone is proposed to describe them. A fault zone is a complex structure, showing different parts with different kinds of deformations and/or materials that could explain chemical and physical processes observed during fluid-rock interactions. The different parts composing the fault zone are: (1) the fault core or gauge zone; (2) the damage zone; (3) and the protolith. They are usually heterogeneous and show different physical properties. The damage zone is a potential high permeability channel and could become the main pathway for fluids if secondary minerals seal the fault core. Porosity is the lowest within the protolith, between 0.5 and 1%, but can go up to 15% in the fault zone. Permeability ranges from 10^?20 m² in the fresh granite to, at least, 10^?15 m² in the fault core, and TC ranges from 2.5 W K^?1m^?1 to 3.7 W K^?1m^?1. Finally, variations in specific surface are set over two orders of magnitude. If the lowest values usually characterize the fresh granite far from fault zones, physical properties could show variations spread over their whole respective ranges within these fault zones.  相似文献   

Associations of very high energy gamma-ray sources discovered by H.E.S.S. with pulsar wind nebulae     

Yves A. Gallant 《Astrophysics and Space Science》2007,309(1-4):197-202

The H.E.S.S. array of imaging Cherenkov telescopes has discovered a number of previously unknown γ-ray sources in the very high energy (VHE) domain above 100 GeV. The good angular resolution of H.E.S.S. (∼0.1° per event), as well as its sensitivity (a few percent of the Crab Nebula flux) and wide 5° field of view, allow a much better constrained search for counterparts in comparison to previous instruments. In several cases, the association of the VHE sources revealed by H.E.S.S. with pulsar wind nebulae (PWNe) is supported by a combination of positional and morphological evidence, multi-wavelength observations, and plausible PWN model parameters. These include the plerions in the composite supernova remnants G 0.9+0.1 and MSH 15–52, the recently discovered Vela X nebula, two new sources in the Kookaburra complex, and the association of HESS J1825–137 with PSR B1823–13. The properties of these better-established associations are reviewed. A number of other sources discovered by H.E.S.S. are located near high spin-down power pulsars, but the evidence for association is less complete. These possible associations are also discussed, in the context of the available multi-wavelength data and plausible PWN scenarios. For the H.E.S.S. Collaboration  相似文献   

Experimental and numerical behaviour of reinforced mortar plates subjected to accelerated corrosion     

Quang Thanh Nguyen  Sabine Caré  Yves Berthaud  Alain Millard  Frédéric Ragueneau 《国际地质力学数值与分析法杂志》2011,35(10):1141-1159

Most reinforced concrete structures are damaged due to corrosion of reinforcements in concrete. In normal conditions the pH near the reinforcements is around 12–13 which means that steel is in a passive state. But aggressive species, such as chloride ions or carbon dioxide, may penetrate into concrete and promote active corrosion. As a consequence (hydro)oxides are produced leading to degradation of concrete structures. For instance cracking of the concrete is generated due to the pressure induced by rust. In this paper, we study the inception and the propagation of cracking on reinforced mortar plates with rebars located either in the middle or at the corner. Additional experiments have been performed on cylindrical specimens to determine the local effect of rust pressure at the interface rust/mortar. The specimens have been subjected to imposed current density in order to enhance the corrosion and digital image intercorrelation has been used to determine displacement fields. The experiments have been compared to numerical modelling. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Lake‐level fluctuations at Lake Bourget (eastern France) around 4500–3500 cal. a BP and their palaeoclimatic and archaeological implications     

Michel Magny  Fabien Arnaud  Yves Billaud  André Marguet 《第四纪科学杂志》2012,27(5):494-502

On the basis of sedimentological analysis of two cores taken at Chatillon, Lake Le Bourget (northern French Pre‐Alps), and well dated by radiocarbon dates in addition to tree ring dates obtained from an archaeological layer, this paper presents a high‐resolution lake‐level record for the period 4500–3500 cal. a BP. The collected data provide evidence of a complex palaeohydrological (climatic) oscillation spanning the ca. 4300–3850 cal. BP time interval, with major lake‐level maxima at ca. 4200 and 4050–3850 cal. a BP separated by a lowering episode around 4100 cal. a BP. The lake‐level highstands observed at Chatillon between 4300 and 3850 cal. BP appear to be synchronous with (i) a major flooding period recorded in deep cores from the large lakes Le Bourget and Bodensee, and (ii) glacier advance and tree line decline in the Alps. Such wetter and cooler climatic conditions in west‐central Europe around 4000 cal. a BP may have been a nonlinear response to decrease and seasonal changes in insolation. They may also provide a possible explanation for the general abandonment of prehistoric lake dwellings north of the Alps between 4360 and 3750 cal. a BP. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Mapping Coastal Aquifers by Joint Inversion of DC and TEM Soundings-Three Case Histories     

Yves Albouy  Pierre Andrieux  Gérard Rakotondrasoa  Michel Ritz  Marc Descloitres  Jean-Lambert Join  Eddy Rasolomanana 《Ground water》2001,39(1):87-97

Electrical and electromagnetic methods are well suited for coastal aquifer studies because of the large contrast in resistivity between fresh water-bearing and salt water-bearing formations. Interpretation models for these aquifers typically contain four layers: a highly resistive unsaturated zone; a surficial fresh water aquifer of intermediate resistivity; an underlying conductive, salt water saturated aquifer; and resistive substratum. Additional layers may be added to allow for variations in lithology within the fresh water and salt water layers. Two methods are evaluated: direct current resistivity and time domain electromagnetic soundings. Use of each method alone produces nonunique solutions for resistivities and/or thicknesses of the different layers. We show that joint inversion of vertical electric and time domain electromagnetic soundings produces a more tightly constrained interpretation model at three test sites than is produced by inversion methods applied to each data set independently.  相似文献   

Detection of turbulent coherent motions in a forest canopy part II: Time-scales and conditional averages     

Serge Collineau  Yves Brunet 《Boundary-Layer Meteorology》1993,66(1-2):49-73

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Reply to the Comment By J. E. T. Channell and J. S. Stoner On 'Magnetostratigraphy of the Hettangian Langmos Section (Adnet, Austria): Evidence For Time-Delayed Phases of Magnetization'     

Yves Gallet  Didier Vandamme  Leopold Krystyn 《Geophysical Journal International》1994,119(3):1008-1008

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La dissolution des mineraux: Aspects cinetiques: T. C. Touray,Editions Masson, 1980, 120 pp     

Yves Tardy 《Geochimica et cosmochimica acta》1981,45(2):277

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Les processus d'érosionàla surface des continents | P. Birot, 1981. Masson,Paris, 607 pp., no price given. In French     

Yves Tardy 《Earth》1982,18(2):175-176

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