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31.
Is the world's economic centre of gravity already in Asia? 总被引:1,自引:0,他引:1
This paper proposes a novel and simple measure of the world's economic centre of gravity. Over the recent decades, this centre has shifted towards Asia, but is still located in Europe. 相似文献
32.
33.
Sergey V. Marchenko Gregor Rauw Eleonora A. Antokhina Igor I. Antokhin Dominique Ballereau Jacques Chauville Michael F. Corcoran Rafael Costero Juan Echevarria Thomas Eversberg Ken G. Gayley Gloria Koenigsberger Anatoly S. Miroshnichenko Anthony F. J. Moffat Nidia I. Morrell Nancy D. Morrison Christopher L. Mulliss Julian M. Pittard Ian R. Stevens Jean-Marie Vreux Jean Zorec 《Monthly notices of the Royal Astronomical Society》2000,317(2):333-342
With the objective of investigating the windwind collision phenomenon and supporting contemporaneous X-ray observations, we have organized a large-scale, coordinated optical monitoring campaign of the massive, highly eccentric O9 III+B1 III binary Iota Orionis. Successfully separating the spectra of the components, we refine the orbital elements and confirm the rapid apsidal motion in the system. We also see strong interaction between the components during periastron passage and detect phase-locked variability in the spectrum of the secondary star. However, we find no unambiguous signs of the bow shock crashing on the surface of the secondary, despite the predictions of hydrodynamic simulations. Combining all available photometric data, we find rapid, phase-locked variations and model them numerically, thus restricting the orbital inclination to 50° i 70°. 相似文献
34.
A numerical model for convective heat and mass transport of compressible or incompressible gas flows with soil-water phase change is presented. In general, the gaseous phase is considered as compressible and the model accounts for adiabatic processes of compression heating and expansion cooling. The inherently compressible gaseous phase may nevertheless be considered as incompressible by adopting the Oberbeck–Boussinesq approximations. The numerical method used to solve the equations that describe natural convection is based on a Galerkin finite element formulation with adaptive mesh refinement and dynamic time step control. As most existing numerical studies have focused on the behavior of incompressible fluids, model substantiation examines the influence of fluid compressibility on two-widely used benchmarks of steady-state convective heat and mass transport. The relative importance of the effect of pressure-compressibility cooling is shown to increase as the thermal gradient approaches the magnitude of the adiabatic gradient. From these results, it may be concluded that pore-air compressibility cannot be neglected in medium to large-sized enclosures at small temperature differentials. After demonstrating its ability to solve fairly complex transient problems, the model is used to further our understanding of the thermal behavior of the toe drain at the LA2-BSU dam in the province of Quebec, Canada. 相似文献
35.
Bruno Bézard André Marten Jean Paul Baluteau Daniel Gautier Jean-Marie Flaud Claude Camy-Peyret 《Icarus》1983,55(2):259-271
The influence of hydrogen sulfide, a still-undetected key molecule for the Jovian atmospheric chemistry in the infrared spectrum, was investigated. Synthetic spectra including various vertical distribution profiles of H2S have been computed and compared with observational data for Jupiter in the 2- to 15-cm?1 and 1160- to 1200-cm?1 spectral ranges. No firm conclusion about the presence of H2S can be drawn from the latter spectral region because of large uncertainties in gaseous opacities. In the microwave range, H2S is found to be a possible candidate to explain the measurements. Constraints to its vertical distribution which would imply a significant supersaturation in the troposphere are derived. Physical and chemical processes involving H2S in the atmosphere are discussed in the light of this hypothesis. 相似文献
36.
Alexander Barth Aida Alvera-Azcárate Jean-Marie Beckers Joanna Staneva Emil V. Stanev Johannes Schulz-Stellenfleth 《Ocean Dynamics》2011,61(5):599-610
Surface winds are crucial for accurately modeling the surface circulation in the coastal ocean. In the present work, high-frequency
radar surface currents are assimilated using an ensemble scheme which aims to obtain improved surface winds taking into account
European Centre for Medium-Range Weather Forecasts winds as a first guess and surface current measurements. The objective
of this study is to show that wind forcing can be improved using an approach similar to parameter estimation in ensemble data
assimilation. Like variational assimilation schemes, the method provides an improved wind field based on surface current measurements.
However, the technique does not require an adjoint, and it is thus easier to implement. In addition, it does not rely on a
linearization of the model dynamics. The method is validated directly by comparing the analyzed wind speed to independent
in situ measurements and indirectly by assessing the impact of the corrected winds on model sea surface temperature (SST)
relative to satellite SST. 相似文献
37.
Ocean Dynamics - In this study, the spatial and temporal variability in surface chlorophyll a (Chl-a) in the whole South China Sea (SCS) was investigated in detail by using 8-day, 4-km, gap-free... 相似文献
38.
Philippe Paillou Ahmed El Barkooky Aly Barakat Jean-Marie Malezieux Bruno Reynard Jean Dejax Essam Heggy 《Comptes Rendus Geoscience》2004,336(16):1491-1500
Using orbital imaging radar, we have detected a large number of circular structures in the southwestern Egyptian desert, covering more than 4500 km2 close to the Gilf Kebir plateau in sandstones of Upper Cretaceous. Fieldwork confirmed that it is a new impact crater field: 13 craters from 20 m to 1 km in diameter were studied. The impact origin is confirmed by the observation of shock-related structures, such as shatter cones and planar fractures in quartz grains of breccia. Considering the extension of the crater field, it was possibly created by several meteorites that broke up when entering the atmosphere. To cite this article: P. Paillou et al., C. R. Geoscience 336 (2004).
Résumé
À partir d'images satellites issues de systèmes radar, nous avons détecté un grand nombre de structures circulaires dans le Sud-Ouest du désert égyptien, s'étendant sur plus de 4500 km2 à l'est du plateau du Gilf Kebir, dans des grès du Crétacé supérieur. Une étude sur le terrain a permis de vérifier qu'il s'agit d'un champ d'impacts météoritiques jusque là inconnu : 13 structures, d'un diamètre compris entre 20 m et 1 km, ont été reconnues comme cratères d'impact. La présence d'un grand nombre de cônes de percussion et de brèches dans lesquelles des quartz choqués à structures planaires ont été observés confirment l'hypothèse de l'impact. Considérant l'extension du champ d'impact, il a probablement été créé par plusieurs météorites qui se sont fragmentées dans l'atmosphère terrestre. Pour citer cet article : P. Paillou et al., C. R. Geoscience 336 (2004). 相似文献39.
Alexander Barth Jean-Marie Beckers Aida Alvera-Azcrate Robert H. Weisberg 《Ocean Modelling》2007,19(3-4):204-218
A method for filtering inertia-gravity waves from elevation and depth-averaged velocity is described. This filtering scheme is derived from the linear shallow water equations for constant depth and constant Coriolis frequency. The filtered solution is obtained by retaining only the eigenvectors corresponding to the geostrophic equilibrium and by discarding explicitly the eigenvectors corresponding to the fast moving inertia-gravity waves. An alternative formulation is derived using a variational approach. Both filtering methods are tested numerically for a periodic domain with constant depth and the variational approach is implemented for a closed domain with large topographic variations. The filtering methods significantly reduce the amplitudes of the inertia-gravity waves while preserving the mean flow. The variational method is compared to the Incremental Analysis Update technique and the benefits of the variational filter are presented. 相似文献
40.
Giovanni Aloisi Ioanna BouloubassiSander K. Heijs Richard D. Pancost Catherine PierreJaap S. Sinninghe Damsté Jan C. GottschalLarry J. Forney Jean-Marie Rouchy 《Earth and Planetary Science Letters》2002,203(1):195-203
To understand the role played by microorganisms in the formation of cold seep carbonates, we conducted an integrated microbial, mineralogical and organic geochemical study of methane-related authigenic carbonate crusts formed on eastern Mediterranean mud volcanoes. We show that supersaturation with respect to carbonate minerals is induced by microbial anaerobic oxidation of methane. Combined lipid biomarker analysis and 16S rRNA gene surveys identified a highly diversified methane-consuming archaeal community possibly comprising novel species, implying that the anaerobic oxidation of methane is phylogenetically widespread and directly implicating these organisms in the process of crust precipitation. Moreover, pore-water sulphate gradients produced by co-occurring methane-based sulphate reduction exert the main control on aragonite versus magnesian calcite precipitation. We propose that this may be the dominant mode of carbonate crust formation at cold seeps world-wide, in agreement with aquatic chemistry predictions and explaining carbonate mineralogy. 相似文献