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SEPARATION OF SCALES IN ELASTICITY IMAGING:A NUMERICAL STUdY

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Journal of Computational Mathematics 2010年第3期28卷 354-370页

作者： Habib Ammari Pierre Garapon Franois Jouve Institut Langevin Laboratoire Ondes et Acoustique laboratoire J.L.Lions Universite Paris Ⅶ laboratoire J.L.Lions Université Paris Ⅶ

In magnetic resonance elastography, one seeks to reconstruct the shear modulus from measurements of the displacement field in the whole body. In this paper, we present an optimization approach which solves the problem by simply minimizing a discrepancy functional. In order to recover a complex anomaly in a homogenous medium, we first observe that the information contained in the wavefield should be decomposed into two parts, a ＂near-field＂ part in the region around the anomaly and a ＂far-field＂ part in the region away from the anomaly. As will be justified both theoretically and numerically, separating these scales provides a local and precise reconstruction.

关键词： Elastography multi-scale imaging anomaly reconstruction.

A survey of the Szeg? equation dedicated to Professor Jean-Yves Chemin on the Occasion of His 60th Birthday

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Science China Mathematics 2019年第6期62卷 1087-1100页

作者： Patrick Gérard Sandrine Grellier laboratoire de Mathématiques d'Orsay Université Paris-Sud CNRSUniversité Paris-Saclay Institut denis Poisson-Université d'Orléans/Université de Tours CNRS UMR

We survey the main properties of the cubic Szeg? equation from the PdE viewpoint, emphasising global existence of smooth solutions, analytic regularity, growth of high Sobolev norms and the effects of weak damping.

关键词： cubic Szego equation integrable system Hankel operator spectral analysis analytic regularity wave turbulence

Quantal studies of sodium 3p ← 3s photoabsorption spectra perturbed by ground lithium atoms

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Chinese Physics B 2019年第6期28卷 146-154页

作者： N Lamoudi F Talbi M T Bouazza M Bouledroua K Alioua Badji Mokhtar University B.P.12 AnnabaAlgeria laboratoire LESIMS laboratoire de Physique des Rayonnements laboratoire LAMA Souk-Ahras University Souk-Ahras 41000Algeria

The pressure broadening in the far wings, where the sodium Na(3 p ← 3 s) resonance line is perturbed by ground lithium Li(2 s) atoms, has been theoretically analyzed. The NaLi potential–energy curves and the transition dipole moments are constructed by using a reliable ab initio data points to carry out the reduced-absorption coefficients k_r(ν, T). This quantum-mechanical investigation have demonstrated that the NaLi profile spectra show a satellite future in the red wing at wavelength λ = 685 nm in the temperature range 4000 K–1.8 × 10~4 K. The computation could also exhibit a second satellite, in the blue wing, near the wavelength λ = 574 nm beyond 6000 K and a third peak located at λ = 490 nm which begins to appear at 1.8 × 10~4 K.

关键词： pressure broadening absorption coefficient satellite structure radiative lifetime

Positron Energy Levels in Cd-Based Semiconductors

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Communications in Theoretical Physics 2013年第6期59卷 756-762页

作者： B.Abbar S.Mécabih S.Amari N.Benosman B.Bouhafs laboratoire de Modélisation et de Simulation en Sciences des département de Physique Université djillali Liabès

Using the full potential linearized augmented plane wave FP-LAPW method within local density ap-proximation LdA, we have studied positron diffusion and surface emission in Cd-based semiconductors. This requires the calculation of electron and positron band structures. In the absence of experimental and theoretical data for CdX (X=S,Se,Te) we have treated the Si, which has been studied by several authors, as a test case. Predictive results on positron effective masses, deformation potentials, positron work functions, diffusion constants and positron mobilities are presented for CdX (X=S, Se, Te). Our calculated data for Si are compared with experimental and recent theoretical results.

关键词： dFT FP-LAPW semiconductors positron diffusion

Modeling Water Infiltration and Solute Transfer in a Heterogeneous Vadose Zone as a Function of Entering Flow Rates

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Journal of Water Resource and Protection 2015年第13期7卷 1017-1028页

作者： Erij Ben Slimene Laurent Lassabatere Thierry Winiarski Remy Gourdon laboratoire d’ecologie des Hydrosystèmes Naturels et Anthropisés (LEHNA) ENTPE Vaulx-en-Velin France laboratoire de Génie Civil et d’Ingénierie Environnementale-déchets Eau Environnement et Pollutions (LGCIE-DEEP) INSA Lyon Villeurbanne France

due to its rapid movement, preferential flow (PF) in the vadose zone allows much faster contaminant transport, which may have a significant impact on ground-water quality. PF can occur in heterogeneous vadose zones and it strongly depends on hydric and hydraulic conditions like entering flow rates at surface. This study deals with the modeling of the establishment of PF, and related solute transfer during the infiltration phase in a strongly heterogeneous glaciofluvial deposit. This deposit is made of four contrasting lithofacies (sand, gravel, bimodal gravel and matrix-free gravel) and lies underneath an urban infiltration basin (Lyon, France). Previous studies have been carried out on this site and linked the regionalization of soil pollution with the lithological heterogeneity. But none of them clearly demonstrated how heterogeneity could impact flow and solute transfer and may explain such a regionalization. In this study, we model flow and solute transfer at the trench scale for both uniform and heterogeneous profiles in order to characterize the effect of lithological heterogeneity. In addition, such a modeling was performed for two different entering flow rates to depict the influence of condition at surface on PF. A key result is that heterogeneity clearly impacts unsaturated flow and solute transfer. Numerical modeling permitted pointing out the existence of PF paths associated with the sedimentary heterogeneity of the glaciofluvial deposit. For lower surface fluxes, the sand lens and matrix-free gravel were the sources of capillary barrier effects, leading to a funneled flow and a groundwater recharge characterized by earlier and more dispersed wetting fronts. Such a flow pattern enhances solutes transfer and reduces solute retention by soil. Thus, the effect of heterogeneity on solute transfer is significant, especially for the most reactive solutes.

关键词： Numerical Modeling Preferential Flow Solute Transfer Infiltration Basin Vadose Zone

Flight initiation distance, color and camouflage

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Current Zoology 2019年第5期65卷 535-540页

作者： Anders Pape MOLLER Wei LIANG diogo S.M.SAMiA laboratoire d'ecologie Systematique et EvolutionCNRS UMRUniversite Paris-SudBatiment 362Orsay CedexFrance Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering College of Life SciencesBeijing Normal UniversityBeijing 100875China Ministry of Education Key Laboratory for Ecology of Tropical Islands College of Life SciencesHainan Normal UniversityHaikouChina department of Ecology Federal University of GoiasGoianiaBrazil

Camouflage is widespread throughout the animal kingdom allowing individuals to avoid detection and hence save time and energy rather than escape from an approaching ***,camouflage is likely to have co-evolved with antipredator ***,we propose that camouflage results in dichotomous escape behavior within and among species with classes of individuals and species with cryptic coloration having shorter flight initiation distances(FIds;the distance at which an individual takes flight when approached by a human).We report the results of 2 tests of this ***,bird species with cryptically colored plumage have consistently shorter FId than closely related species without such *** species with sexually dimorphic plumage,brightly colored adult male common pheasants Phasianus colchicus and golden pheasants Chrysolophus pictus have long and variable FId,whereas cryptically colored juveniles and adult females have short and invariable ***,FId in females was predicted by presence or absence of cryptic color,FId in males and their *** findings are consistent with the hypothesis that risk-taking behavior has been attuned to camouflage,and that species with different levels of camouflage differ consistently in their FId.

关键词： anti-predator behavior birds camouflage crypsis sexual dichromatism

ESSENTIAL APPROXIMATE POINT SPECTRA FOR UPPER TRIANGULAR MATRIX OF LINEAR RELATIONS

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Acta Mathematica Scientia 2013年第4期33卷 1187-1201页

作者： Souhir ELLEUCH Maher MNIF département de Mathématiques Université de Sfax Faculté des Sciences de SfaxLaboratoire de Physiques Mathématiques

When A E ∈LR（H） and B E ∈LR（K） are given, for C E∈LR（K, H） we denoteby Mc the linear relation acting on the infinite dimensional separable Hilbert space H Kof the formIn this paper, we give the necessary and sufficient conditionson A and B for wh{ch Mc is upper semi-Fredholm with negative index or Weyl for some C C ∈LR（K, H）.

关键词： linear relation Fredholm and semi-Fredholm relation essential approximatepoint spectra for linear relation

Instabilities in Coaxial Rotating Jets

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Journal of Thermal Science 2000年第4期9卷 322-326页

作者： Tanja Ivanic Eric Foucault Jean Pecheux Virginie Gilard laboratoire d’Etudes Aérodynamiques (L.E.A. CNRS UMR 6609) Poitiers France

The aim of this study is the characterization of the cylindrical "mixing layer resulting from the interaction of two coaxial swirling jets. The experimental part of this study was performed in a cylindrical water tunnel, permitting an independent rotation of two coaxial jets. The rotations are generated by means of 2×36 blades localized in two swirling chambers. As expected, the evolution of the main instability modes presents certain differences compared to the plane-mixing-layer case. Experimental results obtained by tomography showed the existence of vortex rings and streamwise vortex pairs in the near field region. This method also permitted the observation of the evolution and interaction of different modes. PIV velocity measurements realized in the meridian plans and the plans perpendicular to the jet axis show that rotation distorts the typical top-hat axial velocity profile. The transition of the axial velocity profile from jet-like into wake-like is also observed.

关键词： rotation swirl mixing layer instabilities.

The unexpected occurrence of enigmatic'percevalicrinids'(Echinodermata,Crinoidea)in the Lower Jurassic strata of North Africa—Implications for their stratigraphic and palaeogeographic distribution and discussion on their belonging to the subfamily Balanocrininae

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Journal of Palaeogeography 2023年第3期12卷 434-447页

作者： Mariusz A.Salamon Madani Benyoucef Karolina Paszcza Faycal Mekki Imad Bouchemla Bartosz J.Plachno University of Silesia in Katowice Faculty of Natural SciencesBedzinska 60PL-41-200 SosnowiecPoland laboratoire de Géomatique Ecologie et EnvironnementMustapha Stambouli University29000 MascaraAlgeria Jagiellonian University in Krakow Faculty of BiologyInstitute of BotanyGronostajowa Street 9PL-30-387 CracowPoland

The marl and limestone alternations of the Lower Jurassic Ain Ouarka and Ain Rhezala formations(Pliensbachian-Toarcian)in the western Saharan Atlas,Northwest Algeria,yield a diverse micro-and mac-rofauna,including moderately numerous crinoids,which are represented by remains of isocrinids,i.e.,Bal-anocrinus ticinensis Hess and columnals of the genus *** far,the latter genus has been observed from the Upper Jurassic-Lower Cretaceous strata of Eurasia,North America,and the African ***,the present find is the oldest record of this crinoid genus,and the second one from the southern Tethyan *** this paper,it is shown that Percevalicrinus,which is traditionally regarded as a representative of the subfamily Balanocrininae,displays several features of the subfamily *** crinoid assemblage and associated facies and invertebrate fauna are typical of a low-energy deep outer shelf/ramp(below the storm wave-base)setting.

关键词： Echinoderms Crinoids Isocrinids Percevalicrinids Percevalicrinus Lower Jurassic Algeria Maghrebian Tethys