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S. Jabri H. Souissi A. Souissi A. Meftah V. Sallet A. Lusson P. Galtier M. Oueslati 《Journal of Raman spectroscopy : JRS》2015,46(2):251-255
Wurtzite ZnO thin films were prepared on sapphire substrate by metal organic chemical vapor deposition (MOCVD). Raman scattering studies on different crystallographic textures were performed in the backscattering geometry, and polarization effect is investigated in different configurations and . ZnO Raman modes are investigated in each texture. In the case of ZnO thin film deposed on r‐() sapphire plane and using backscattering geometry, new Raman line was observed at 390 cm−1 because this mode has not been noticed in this geometry. It is shown that the frequencies of the quasi‐phonon modes of the examined thin film are in good agreement with the theoretical values calculated within the framework of Loudon model. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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A posteriori error analysis for nonconforming approximations of an anisotropic elliptic problem
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Boujemâa Achchab Abdellatif Agouzal Adil Majdoubi Driss Meskine Ali Souissi 《Numerical Methods for Partial Differential Equations》2015,31(3):950-976
We develop in this article an a posteriori error estimator for the P1‐nonconforming finite element approximation, for a diffusion‐reaction equation. We adopt the error in a constitutive law approach in two and three dimensional space, for not necessary piecewise constant data of problems. The efficiency and the reliability of our estimators are proved, neither Helmholtz decomposition of the error nor saturation assumption. The constants are explicitly given, which prove the robustness of these estimators. © 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 31: 950–976, 2015 相似文献
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B. Achchab A. Agouzal M. El Fatini A. Souissi 《Numerical Methods for Partial Differential Equations》2012,28(5):1717-1728
We construct a hierarchical a posteriori error estimator for a stabilized finite element discretization of convection‐diffusion equations with height Péclet number. The error estimator is derived without the saturation assumption and without any comparison with the classical residual estimator. Besides, it is robust, such that the equivalence between the norm of the exact error and the error estimator is independent of the meshsize or the diffusivity parameter. © 2012 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2012 相似文献
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Bouchonnet S Kinani S Souissi Y Bourcier S Sablier M Roche P Boireau V Ingrand V 《Rapid communications in mass spectrometry : RCM》2011,25(1):93-103
With the future aim of using gas chromatography coupled with mass spectrometry to characterize the transformation products of ozonated herbicides: metolachlor, acetochlor and alachlor, an interpretation of their electron ionization mass spectra is presented. Fragmentation mechanisms are proposed on the basis of isotopic labelling and multiple-stage mass spectrometry experiments carried out on an ion trap mass spectrometer. We also give examples in order to demonstrate how the elucidation of such fragmentation mechanisms for herbicides may simplify the characterization of their ozonation products. 相似文献
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A. Souissi A. Marzouki A. Sayari V. Sallet A. Lusson M. Oueslati 《Journal of Raman spectroscopy : JRS》2011,42(7):1574-1577
In this work, we present a detailed Raman scattering study to clarify the origin of the mode at 379 cm−1 which is observed in Raman spectra of the ZnO films grown on c‐sapphire substrates and generally attributed to the A1‐transverse optical (A1‐TO) mode of ZnO. The studied ZnO films were deposited by metal‐organic chemical vapor deposition on c‐sapphire and (0001) ZnO substrates. In the z(−,−)z̄ backscattering configuration, the A1‐TO mode is forbidden, while the 379 cm−1 peak is still observed in the as‐deposited film grown on sapphire substrate. However, this mode is not observed in Raman spectra of the as deposited film grown on ZnO substrate. We suggest that the peak at 379 cm−1 is the E1g mode of the sapphire substrate which is allowed in z(−,−)z̄ backscattering configuration. The effects of annealing, the substrate and the collection cross‐section on Raman active modes were analyzed. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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In this work, we study the error in the approximation of the solution of elliptic partial differential equations obtained with the nonconforming finite elements method; we adopt the error in a constitutive law approach. 相似文献
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Functional Analysis and Its Applications - Using a change of basis in the algebra of symmetric functions, we compute the moments of the Hermitian Jacobi process. After a careful arrangement of... 相似文献
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We consider here, the fluctuations of turbidity, oxygen and pH time series recorded from the MAREL system (Ifremer, France), which is based on the deployment of data buoys equipped with water analysis capabilities in an automated mode. We perform a spectral analysis (from 10 min to years) of these time series, and we estimate their probability density functions. Oxygen, turbidity and pH are important quantities for ecosystem studies and physics-biology couplings, and their fluctuations reveal the possible influence of environmental factors such as tides and turbulence. Turbidity variability is highly complex and does not appear to be directly coupled to turbulence, since no clear range is visible. On the other hand, oxygen percentage of saturation and pH data show remarkably nice scaling ranges, indicating an important coupling with turbulence, but also biological or chemical activity, since the statistics differ markedly from passive scalars. Several possible sources of this variability are discussed. 相似文献