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排序方式: 共有86条查询结果,搜索用时 15 毫秒
21.
Kissi Benaissa Parron Vera Miguel Angel Rubio Cintas Maria Dlolores Dubujet Philippe Khamlichi Abdellatif Bezzazi Mohammed El Bakkali Larbi 《Applied Mathematical Modelling》2012
CFD simulation with enhanced modeling of turbulence and near-wall treatment is used to model water–clay mixtures flowing through a cylindrical pipe domain. Effects on the wall-shear stress resulting from varying water clay content and applied hydraulic gradient are analyzed. Various parametric studies were performed and had shown that the two-dimensional modelling introduced in the present study does not yield a uniform wall-shear stress along the pipe wall and that clay concentration affects significantly the wall-shear stress value. This is in contrast with the common hypothesis used in one-dimensional modeling approaches where this stress is assumed constant and which gives rise to uniform erosion along the pipe wall. The obtained results had enabled predicting more realistically erosion amount and had allowed for understanding the irregular eroded hole wall shape as observed experimentally after performing the standard hole erosion test. 相似文献
22.
Elaissi A Rouis Z Mabrouk S Salah KB Aouni M Khouja ML Farhat F Chemli R Harzallah-Skhiri F 《Molecules (Basel, Switzerland)》2012,17(3):3044-3057
The essential oils of fifteen Eucalyptus species harvested from the Jbel Abderrahman and Korbous arboreta (North East Tunisia) were screened for their antibacterial activities by the agar disc diffusion method. Eighteen major components as identified by GC/FID and GC/MS were selected for a study of the chemical and biological activity variability. The main one was 1,8-cineole, followed by spathulenol, trans-pinocarveol, α-pinene, p-cymene, globulol, cryptone, β-phellandrene, viridiflorol, borneol, limonene and isospathulenol. The chemical principal component analysis identified five species groups and subgroups, where each group constituted a chemotype, however that of the values of zone diameter of the inhibition (zdi) identified six groups of Eucalyptus oils, characterized by their antibacterial inhibition ability. The strongest activity was shown by E. platypus oil against Enterococcus faecalis and by E. lamannii oil against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. A correlation between the levels of some major components and the antibacterial activities was observed. 相似文献
23.
Mustapha Aitali Larbi El Firdoussi Abdellah Karim Alejandro F. Barrero Miguel Quirs 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(9):1088-1089
The title compound, [(S)‐2‐(anilinomethyl)pyrrolidine‐N,N′]‐chloro(η6‐para‐cymene)ruthenium(II) chloride, [RuCl‐(C10H14)(C11H16N2)]Cl, has been synthesized by the reaction of [RuCl2(p‐cymene)]2 (p‐cymene is para‐isopropyltoluene) with (S)‐2‐(anilinomethyl)pyrrolidine in triethylamine/2‐propanol. The Ru atom is in a pseudo‐tetrahedral environment coordinated by a chloride ligand, the aromatic hydrocarbon is linked in a η6 manner and the amine is linked via its two N atoms. The chloride anion is involved in hydrogen bonding with the diamine moieties through N—H?Cl interactions, with N?Cl distances of 3.273 (4) and 3.352 (4) Å. 相似文献
24.
Mouhammad El Hassan Laurent Keirsbulck Larbi Labraga 《Flow, Turbulence and Combustion》2009,82(3):359-374
The flow over a deep cavity at low subsonic velocity is considered in the present paper. The cavity length-to-depth aspect
ratio is L/H = 0.2. Single hot-wire measurements characterized the incident turbulent boundary layer and show the influence of the cavity
on the streamwise statistic components just downstream from the cavity. The streamwise mean and fluctuating velocity profiles
are affected by the cavity. PIV measurements reveal the presence for ejection-like events responsible of local perturbations
of the skewness and the flatness coefficients. Time-resolved PIV technic is also used to characterize phase properties of
shear layer oscillating cycle. It is shown that for deep cavity with first Rossiter mode, only one vortical structure is formed
at the cavity leading edge. Then, it grows while convecting downstream along the shear layer. A well-defined ejection process
begins after the vortex impact near the cavity downstream corner. A cylinder device placed spanwisely near the cavity leading
edge eliminates the resonance and highly modifies the behavior of the shear layer flow. In fact, the shear layer could be
divided into upper and lower parts with different structure aspects. 相似文献
25.
Lotfi Rghioui Lahcen El Ammari Larbi Benarafa Jean Pierre Wignacourt 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(7):i90-i91
The crystal structure of dipotassium caesium ytterbium bis(phosphate) is built up from regular independent PO4 tetrahedra and YbO6 octahedra sharing corners and arranged in layers. The structure is, in many respects, similar to that of glaserite. 相似文献
26.
Larbi Berrahmoune 《Rendiconti del Circolo Matematico di Palermo》2005,54(2):273-290
This paper considers the problem of stabilization of linear control systems in Hilbert space with nonlinear feedback. Extensions
of known results in the linear feedback case to the nonlinear one are given. 相似文献
27.
Larbi Alaoui 《Semigroup Forum》2001,63(3):330-356
In this paper nonlinear homogeneous retarded differential equations and models from population dynamics and epidemiology
are considered and studied by the use of translation semigroup theory. We show that the corresponding solution semigroups
are equivalent to appropriate translation semigroups. Existence results for the retarded equations are established by taking
the space of initial functions of the form W
1,p
((-r,0),F) where F is a Banach space, 1≤ p<∈fty and 0<r\le∈fty .
June 28, 1999 相似文献
28.
Touahir L Galopin E Boukherroub R Gouget-Laemmel AC Chazalviel JN Ozanam F Saison O Akjouj A Pennec Y Djafari-Rouhani B Szunerits S 《The Analyst》2011,136(9):1859-1866
The use of an amorphous silicon-carbon alloy overcoating on silver nanostructures in a localized surface plasmon resonance (LSPR) sensing platform allows for decreasing the detection limit by an order of magnitude as compared to sensors based on gold nanostructures deposited on glass. In addition, silver based multilayer structures show a distinct plasmonic behaviour as compared to gold based nanostructures, which provides the sensor with an increased short-range sensitivity and a decreased long-range sensitivity. 相似文献
29.
A. Belasri N. Larbi Daho Bachir Z. Harrache 《Plasma Chemistry and Plasma Processing》2013,33(1):131-146
This paper reports the study of the Kr–Cl2 plasma chemistry in terms of the homogenous model of a dielectric barrier discharge and for two kinds of the applied voltage excitation shape. The effect of Cl2 concentration in the gas mixture, as well as gas pressure and power frequency on the discharge efficiency and the 222 nm photon generation, under typical experimental operating conditions, have been investigated and discussed. Calculations suggest that the overall conversion efficiency from electrical energy to ultraviolet emission in the lamp is in the range of 4.4–12 %, and it will be very affected at high chlorine percentage (>1 %) and high gas pressure (>200 Torr). A comparison between the sinusoidal and the burst excitation waveforms reveals that the burst excitation method provides an enhanced light source performance compared to the sinusoidal wave. 相似文献
30.