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141.
Deep geological repository involving a multibarrier system constitutes one of the most promising options for isolating high‐level radioactive waste from the human environment. To certify the efficiency of waste isolation, it is essential to understand the behaviour of confining geomaterial under a variety of environmental conditions. To this end, results from a near‐to‐real experiment, the full‐scale engineered barriers in situ experiment, are studied by means of a thermo–hydro–mechanical finite element approach, including a consistent thermoplastic constitutive model for unsaturated soils. Laboratory tests are simulated to calibrate model parameters. The results of the numerical simulations are compared with sensor measurements and show the ability of the model to reproduce the main behavioural features of the system. The influence of the hysteretic and temperature‐dependent retention of water on the mechanical response is exhibited. Finally, those results are interpreted in the light of thermoplasticity of unsaturated soils, which reveals the highly coupled and non‐linear characters of the processes encountered. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
142.
Emmanuel Discamps Jacques Jaubert François Bachellerie 《Quaternary Science Reviews》2011,30(19-20):2755-2775
The evolution in the selection of prey made by past humans, especially the Neandertals and the first anatomically modern humans, has been widely debated. Between Marine Isotope Stages (MIS) 5 and 3, the accuracy of absolute dating is still insufficient to precisely correlate paleoclimatic and archaeological data. It is often difficult, therefore, to estimate to what extent changes in species procurement are correlated with either climate fluctuations or deliberate cultural choices in terms of subsistence behavior. Here, the full development of archeostratigraphy and Bayesian statistical analysis of absolute dates allows the archeological and paleoclimatic chronologies to be compared. The variability in hunted fauna is investigated using multivariate statistical analysis of quantitative faunal lists of 148 assemblages from 39 archeological sequences from MIS 5 through MIS 3. Despite significant intra-technocomplex variability, it is possible to identify major shifts in the human diet during these stages. The integration of archeological data, paleoclimatic proxies and the ecological characteristics of the different species of prey shows that the shifts in large game hunting can be explained by an adaptation of the human groups to climatic fluctuations. However, even if Middle and Early Upper Paleolithic men adapted to changes in their environment and to contrasting landscapes, they ultimately belonged to the ecosystems of the past and were limited by environmental constraints. 相似文献
143.
Rafael Rosolem Hoshin V. Gupta W. James Shuttleworth Luis Gustavo Gonçalves de Gonçalves Xubin Zeng 《水文研究》2013,27(14):2075-2097
In climate models, the land–atmosphere interactions are described numerically by land surface parameterization (LSP) schemes. The continuing improvement in realism in these schemes comes at the expense of the need to specify a large number of parameters that are either directly measured or estimated. Also, an emerging problem is whether the relationships used in LSPs are universal and globally applicable. One plausible approach to evaluate this is to first minimize uncertainty in model parameters by calibration. In this paper, we conduct a comprehensive analysis of some model diagnostics using a slightly modified version of the Simple Biosphere 3 model for a variety of biomes located mainly in the Amazon. First, the degree of influence of each individual parameter in simulating surface fluxes is identified. Next, we estimate parameters using a multi‐operator genetic algorithm applied in a multi‐objective context and evaluate simulations of energy and carbon fluxes against observations. Compared with the default parameter sets, these parameter estimates improve the partitioning of energy fluxes in forest and cropland sites and provide better simulations of daytime increases in assimilation of net carbon during the dry season at forest sites. Finally, a detailed assessment of the parameter estimation problem was performed by accounting for the decomposition of the mean squared error to the total model uncertainty. Analysis of the total prediction uncertainty reveals that the parameter adjustments significantly improve reproduction of the mean and variability of the flux time series at all sites and generally remove seasonality of the errors but do not improve dynamical properties. Our results demonstrate that error decomposition provides a meaningful and intuitive way to understand differences in model performance. To make further advancements in the knowledge of these models, we encourage the LSP community to adopt similar approaches in the future. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
144.
François R. Bouchet 《Astrophysics and Space Science》2004,290(1-2):69-85
After recalling the current understanding of the formation of the large scale structures of the Universe which the distribution of galaxies revealed, I review what the imprint on the Cosmic Microwave Background (CMB) of the seeds of these structures can tell us, has already told us, and what it should tell us within the next five years. 相似文献
145.
Star formation in starburst galaxies from near-IR spectroscopy and evolutionary population synthesis
We show that the combined study of the near-IR Stellar Energy Distribution (SED) and emission lines in IR luminous starburst galaxies, using evolutionary population synthesis, gives constraints both on the star formation (SF) parameters and on the relative spatial distribution of the components (burst stars, evolved stars, H II regions, dust). We also note that the He I λ 2.06/Br γ ratio, used to constrain the stellar upper mass limit, is sensitive to a variety of other factors that should be accounted for. 相似文献
146.
Can Battal Kılınç 《Astrophysics and Space Science》2004,289(1-2):103-109
Einstein's equations with variable gravitational and cosmological constants are considered in the presence of a perfect fluid for the anizotropic Bianchi I universe in a way which conserving the energy-momentum tensor. Two solutions are found, one of which the cosmological term varies inversely with power law of time. The other of which cosmological term is constant. 相似文献
147.
Acta Geotechnica - Experimental investigations on the expansion behavior of clayey soils are of great importance to correctly understand the response of the soil–foundation. In this context,... 相似文献
148.
Bachoc François Durrande Nicolas Rullière Didier Chevalier Clément 《Mathematical Geosciences》2022,54(5):941-977
Mathematical Geosciences - Kriging is a widely employed technique across computer experiments, machine learning and geostatistics. An important challenge for kriging is its high costs when dealing... 相似文献
149.
Acta Geotechnica - Hydrophobized sands have been suggested as materials for hydraulic barriers in infrastructure. When placed at the interface ground–atmosphere, environmental factors such as... 相似文献
150.