Éditeur(s) : HAL CCSD
Résumé : International audience
NSS'88
Amherst, United States

hal-01535426
https://hal.univ-antilles.fr/hal-01535426

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
In this paper, we have presented a spectral and a multifractal analysis performed on 412 time series of wind speed data each of duration of 350 s and sampled at 20 Hz. The average spectrum for the wind speed displays a scaling behavior, in the inertial range, over two decades, with b ¼ 1:68 close to the Kolmogorov value À 5/3. A multifractal analysis has been motivated by the presence of scaling invariance in data set. Then we have considered their scaling properties in the framework of fully developed turbulence and multifractal cascades. The results obtained for wind speed confirm that the exponent scaling function z V ðqÞ is nonlinear and concave. This exponent characterizes the scaling functions in the inertial range indicating that the wind speed is intermittent and multifractal. Moreover the theoretical quadratic relation for lognormal multifractals is well fitted. We investigate the consequence for wind energy production: we generate stochastic simulations of a multifractal random walk, and using a power curve derived from experimental data, we generate the associated power time series. We show that, due to the saturation of the power curve for large speed values, when the input time series (turbulent wind speed) is multifractal, the output can be almost monofractal.
ISSN: 0167-6105

hal-01527886
https://hal.archives-ouvertes.fr/hal-01527886
DOI : 10.1016/j.jweia.2012.06.002

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Rh (Rhesus) is a major blood group system in man, which is clinically significant in transfusion medicine. Rh antigens are carried by an oligomer of two major erythroid specific polypeptides, the Rh (D and CcEe) proteins and the RhAG glycoprotein, that shared a common predicted structure with 12 transmembrane a-helices (M0 to M11). Non erythroid homologues of these proteins have been identified (RhBG and RhCG), notably in diverse organs specialized in ammonia production and excretion, such as kidney, liver and intestine. Phylogenetic studies and experimental evidence have shown that these proteins belong to the Amt/Mep/Rh protein superfamily of ammonium/methylammonium permease, but another view suggests that Rh proteins might function as CO2 gas channels. Until recently no information on the structure of these proteins were available. However, in the last two years, new insight has been gained into the structural features of Rh proteins (through the determination of the crystal structures of bacterial AmtB and archeaebacterial Amt-1. Here, models of the subunit and oligomeric architecture of human Rh proteins are proposed, based on a refined alignment with and crystal structure of the bacterial ammonia transporter AmtB, a member of the Amt/Mep/Rh superfamily. This alignment was performed considering invariant structural features, which were revealed through Hydrophobic Cluster Analysis, and led to propose alternative predictions for the less conserved regions, particularly in the N-terminal sequences. The Rh models, on which an additional Rh-specific, N-terminal helix M0 was tentatively positioned, were further assessed through the consideration of biochemical and immunochemical data, as well as of stereochemical and topological constraints. These models highlighted some Rh specific features that have not yet been reported. Among these, are the prediction of some critical residues, which may play a role in the channel function, but also in the stability of the subunit structure and oligomeric assembly. These results provide a basis to further understand the structure/function relationships of Rh proteins, and the alterations occurring in variant phenotypes.
ISSN: 1246-7820

hal-00112914
https://hal.archives-ouvertes.fr/hal-00112914
DOI : 10.1016/j.tracli.2006.02.001

Éditeur(s) : HAL CCSD Springer Verlag (Germany)
Résumé : International audience
We present an N=2 multiplet including a three-index antisymmetric tensor gauge potential, and describe it as a solution to the Bianchi identities for the associated fieldstrength superform, subject to some covariant constraints, in extended central charge superspace. We find that this solution is given in terms of an 8+8 tensor multiplet subject to an additional constraint. We give the transformation laws for the multiplet as well as invariant superfield and component field lagrangians, and mention possible couplings to other multiplets. We also allude to the relevance of the 3-form geometry for generic invariant supergravity actions.
ISSN: 1434-6044

hal-00769902
https://hal.univ-antilles.fr/hal-00769902
DOI : 10.1007/s100520050118

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The purpose of this article is to improve modeling of solar irradiance through the analysis of measurement data on the ground in the intertropical zone. For this, we identify, using information criteria, the probabilistic distributions introduced in two models of synthetic solar irradiance generation. We then validate the results by using the KL divergence and KSI parameter as comparison criteria between distributions arising from real and synthesized data. Our study confirms, for example, that the Gaussian classical distribution is not suitable for modeling solar irradiance, and we propose other more suitable statistical laws instead. The value of the identification procedure of the distribution laws presented in this article is that it ensures the production of solar irradiance data comparable in their statistical content to the measured data. Another advantage is that this procedure contributes to highlighting the time invariance of distribution laws representing the random terms. We conclude that this new information-criteria-based method permits the identification of the probability laws that best describe the statistical distributions introduced in models of synthetic solar irradiance generation.
ISSN: 0038-092X

meteo-01304572
https://hal-meteofrance.archives-ouvertes.fr/meteo-01304572
https://hal-meteofrance.archives-ouvertes.fr/meteo-01304572/document
https://hal-meteofrance.archives-ouvertes.fr/meteo-01304572/file/Manuscript_Hal.pdf
DOI : 10.1016/j.solener.2016.02.038

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
Melting phase relations of model carbonated peridotite in the system CaO-MgO-Al2O3-SiO2-CO2 from 2 to 3 GPa are reported. Experimentally produced melts, which are model carbonatites, with approximately 36-40 wt % CaO, 12-17 wt % MgO, 0.2-1.5 wt % Al2O3, 1-4 wt % SiO2, and 40-42 wt % CO2 (carbon dioxide) are present at all pressures investigated. At 2.8 and 3 GPa, carbonatitic melts are seen experimentally at temperatures that are very close to the vapor-free (CO2) peridotite solidus and are found in equilibrium with forsterite, orthopyroxene, clinopyroxene, and garnet. Solidus phase relations with isobaric and pressure-temperature invariant points, defining the so-called carbonated peridotite solidus ledge, are also reported from 2.1 to 3 GPa. A divariant region exists from 2 to 2.6 GPa wherein two, compositionally different melts are present. In this region, these two melts, carbonatitic and silicate in composition, coexist with crystalline phase assemblage and free vapor. The silicate liquid has approximately 30-48 wt % SiO2 and approximately 6 to 20 wt % of dissolved CO2. The presence of carbonatitic and silicate liquids is interpreted to be due to liquid immiscibility. On the basis of melting phase relations reported here, we conclude that (a) the ledge is a feature along which model carbonatitic liquids are produced by reaction of silicates and CO2 vapor and (b) alkali-free carbonatites and silicate melts can form through melt unmixing at depths of ~60-80 km in the Earth's mantle.
ISSN: 0148-0227

hal-01053913
https://hal.archives-ouvertes.fr/hal-01053913
DOI : 10.1002/2013JB010913

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
In this paper, we have presented a spectral and a multifractal analysis performed on 412 time series of wind speed data each of duration of 350 s and sampled at 20 Hz. The average spectrum for the wind speed displays a scaling behavior, in the inertial range, over two decades, with β=1.68 close to the Kolmogorov value −5/3. A multifractal analysis has been motivated by the presence of scaling invariance in data set. Then we have considered their scaling properties in the framework of fully developed turbulence and multifractal cascades. The results obtained for wind speed confirm that the exponent scaling function ζV(q) is nonlinear and concave. This exponent characterizes the scaling functions in the inertial range indicating that the wind speed is intermittent and multifractal. Moreover the theoretical quadratic relation for lognormal multifractals is well fitted. We investigate the consequence for wind energy production: we generate stochastic simulations of a multifractal random walk, and using a power curve derived from experimental data, we generate the associated power time series. We show that, due to the saturation of the power curve for large speed values, when the input time series (turbulent wind speed) is multifractal, the output can be almost monofractal.
ISSN: 0167-6105

hal-00779049
https://hal.archives-ouvertes.fr/hal-00779049
DOI : 10.1016/j.jweia.2012.06.002