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51.
The objective of this paper is to characterize the hydrodynamic and thermal behaviors of yield stress fluids within a cylindrical agitated vessel equipped with simple helical ribbon stirrers (SHR) (one and two-stages) by means of the numerical simulation approach. For this purpose, a computational fluid dynamic simulation using the 3D finite volume technique has been carried out to solve the continuity, momentum and thermal energy equations. In this study, we have analyzed the Oldroyd and Reynolds numbers effects on the hydrodynamic and thermal behaviors for the two mentioned stirrers types. In addition, the influence of the impeller width and its clearance from the vessel wall on the velocity and thermal fields has been investigated. Velocity and thermal fields’ visualization has been presented in different (r–z) and (r–θ) planes. Moreover, the power constant and Nusselt number are correlated by a relationship relating the physical properties and the geometric ratios defining the SHR. 相似文献
52.
M. Zemzemi S. Alaya Z. Ben Ayadi 《Journal of Experimental and Theoretical Physics》2014,118(6):945-950
Solar cells based on transparent conductive oxides such as ZnO/Cu2O constitute a very advanced way to build high-performance cells. In this work, we are interested in the characterization of the interface through nanoscale modeling based on ab initio approaches (density functional theory, local density approximation, and pseudopotential). This work aims to build a supercell containing a heterojunction ZnO/Cu2O and study the structural properties and the discontinuity of the valence band (band offset) from a semiconducting to another phase. We build a zinc oxide in the wurtzite structure along [0001] on which we place the copper oxide in the hexagonal (CdI2-type) structure. We choose the method of Van de Walle and Martin to calculate the energy offset. This approach fits well the density functional theory. Our calculation of the band offset gives a value that corresponds to other experimental and theoretical values. 相似文献
53.
Burel-Deschamps L Mével M Loizeau D Ayadi F Yaouanc JJ Clément JC Jaffrès PA Giamarchi P 《Journal of fluorescence》2008,18(5):835-841
We report here a study on the physicochemical properties of cationic phospholipids liposomes used for lipoplex formulation
and DNA transfer. The original cationic phospholipids synthesized in our laboratory are first presented with the liposome
formulation process. The second part deals with the liposomes fusogenic properties studied by fluorescence resonant energy
transfer (FRET). The nature of the cationic polar head and the formulation with or without a neutral colipid have a great
influence on the FRET signal. The third part reports the study of the viscosity of the liposome by fluorescence anisotropy
measurements. It has been observed that the vectors having a saturated lipid chain exhibit a more pronounced anisotropy than
those having unsaturated lipid chains. Finally, liposomes formed by a mixture of phospholipids and DC-Chol (a rigid lipid)
leads to increase the anisotropy denoting a more rigid liposome. 相似文献
54.
A. Adanlété Adjanoh J. Vogel M. Ayadi 《Journal of magnetism and magnetic materials》2010,322(17):2498-2504
We present a study of the magnetization reversal dynamics in ultrathin Au/Co/Au films with perpendicular magnetic anisotropy, for a Co thickness of 0.5, 0.7 and 1 nm. In these films, the magnetization reversal is dominated by domain nucleation for tCo=0.5, 0.7 nm and by domain wall propagation for tCo=1 nm. The prevalence of domain nucleation for the thickness range 0.5-0.7 nm is different from results reported in the literature, for the same system and for the same thickness range, where the magnetization reversal took place mainly by domain wall motion. We attribute this difference to the effect of roughness of the Au buffer layer on the morphology of the magnetic layer. 相似文献
55.
This paper investigates the feedback stabilization of non-homogeneous delayed bilinear systems in Hilbert state space. More precisely, under an observability-like assumption, we prove the exponential and strong stability of the solution by using bounded feedback control. Partial stabilization is discussed as well. The proofs of the main results are based on the decomposition method. The decay estimates of the stabilized solutions are obtained. Finally, some examples are presented. 相似文献