排序方式: 共有128条查询结果,搜索用时 0 毫秒
71.
72.
In this paper the amount of liquid left inside of a circular tube and a rectangular channel when displaced by another immiscible fluid are determined by solving the full creeping‐motion equations. The exact continuity of stress on the free surface is employed with a finite difference method. In order to solve the equations, the steady‐state shape of the interface is guessed and the normal stress boundary condition is dropped. The equations based on a stream function‐vorticity formulation are solved with the aid of elliptic grid generation. The computed results are compared with the experimental results of Taylor (J. Fluid Mech. 1961; 10: 161), the theoretical results of Reinelt and Saffman (SIAM J. Sci. Stat. Comput. 1985; 6: 542) and our experimental data. The computed results are in close agreement with our experimental data and those of previous investigators. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
73.
74.
Effect of the acid activation levels of montmorillonite clay on the cetyltrimethylammonium cations adsorption 总被引:2,自引:0,他引:2
Kooli F Khimyak YZ Alshahateet SF Chen F 《Langmuir : the ACS journal of surfaces and colloids》2005,21(19):8717-8723
For the first time, the intercalation properties of acid-activated montmorillonites treated at different acid/clay (w/w) ratios with a cationic surfactant cetyltrimethylammonium (C16TMA) hydroxide are reported. The acid activation causes a reduction in the number of cation exchange sides and, hence improves the exfoliation of the silicate sheets at higher pH values. The basal spacing increases significantly from 1.54 to 3.80 nm, and is related to the acid activation extent. The acid activated clays with acid/clay ratios above 0.2 intercalated significant amounts of C16TMA cations with a basal spacing of 3.8 nm compared to the non acid activated montmorillonite with a basal spacing of 2.10 nm. The 13C CP/MAS NMR indicates that the intercalated surfactants exhibit a significant degree of gauche conformation in the acid-activated clays. According to in-situ powder XRD, an increase of the basal spacing to 4.08 nm is observed at intermediate temperatures of 50-150 degrees C for organoclay with basal spacing of 3.80 nm, at higher temperatures above 300 degrees C, the decomposition of the surfactant occurs and the basal spacing decreases to a value of about 1.4 nm, with the persistence of a reflection at 3.8 nm for clay at a higher acid/clay ratio of 0.5. 相似文献
75.
Fethi Kamışlı 《Transport in Porous Media》2009,80(2):345-371
The flow of an incompressible Newtonian fluid confined in a planar geometry with different wall temperatures filled with a
homogenous and isotropic porous medium is analyzed in terms of determining the unsteady state and steady state velocities,
the temperature and the entropy generation rate as function of the pressure drop, the Darcy number, and the Brinkman number.
The one-dimensional approximate equation in the rectangular Cartesian coordinates governing the flow of a Newtonian fluid
through porous medium is derived by accounting for the order of magnitude of terms as well as accompanying approximations
to the full-blown three-dimensional equations by using scaling arguments. The one-dimensional approximate energy and the entropy
equations with the viscous dissipation consisting of the velocity gradient and the square of velocity are derived by following
the same procedure used in the derivation of velocity expressions. The one-dimensional approximate equations for the velocity,
the temperature, and the entropy generation rate are analytically solved to determine the velocity, the temperature, and the
entropy distributions in the saturated porous medium as functions of the effective process parameters. It is found that the
pressure drop, the Darcy number, and the Brinkman number affect the temperature distribution in the similar way, and besides
the above parameters, the irreversibility distribution ratio also affects the entropy generation rate in the similar way. 相似文献
76.
Zied Cheheb Fethi Albouchi Sassi Ben Nasrallah 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(4):620-635
This paper deals with a theoretical and an experimental study allowing the measurement of the radiative and the conductive properties of semitransparent materials. The method consists of applying a crenel heat flux on the front face of a semitransparent sample and recording the temperature at the rear face using an open thermocouple junction.Parameter identification is performed by the minimization of the ordinary least-squares function comparing the measured and the calculated temperatures. This later is obtained from the thermal model describing the heat transfer by conduction and radiation in the medium. This model is built by the thermal quadrupole formalism.Measurements are reported on commercial glasses and plexiglass samples, and the used iterative algorithm is based on the Gauss-Newton method. 相似文献
77.
Fethi SOLTANI 《数学研究及应用》2022,42(1):8-14
In this work,we prove Clarkson-type and Nash-type inequalities for the Laguerre transform■on M=[0,∞)×R.By combining these inequalities,we show Laeng-Morpurgo-type uncertainty inequalities.We establish also a local-type uncertainty inequalities for the Laguerre transform■,and we deduce a Heisenberg-Pauli-Weyl-type inequality for this transform. 相似文献
78.
This paper presents a comprehensive review of 196 studies which employ operational research (O.R.) and artificial intelligence (A.I.) techniques in the assessment of bank performance. Several key issues in the literature are highlighted. The paper also points to a number of directions for future research. We first discuss numerous applications of data envelopment analysis which is the most widely applied O.R. technique in the field. Then we discuss applications of other techniques such as neural networks, support vector machines, and multicriteria decision aid that have also been used in recent years, in bank failure prediction studies and the assessment of bank creditworthiness and underperformance. 相似文献
79.
Fethi BEN BELGACEM 《数学物理学报(B辑英文版)》2018,38(4):1285-1295
In this paper, we introduce and study a method for the numerical solution of the elliptic Monge-Ampère equation with Dirichlet boundary conditions. We formulate the Monge-Ampère equation as an optimization problem. The latter involves a Poisson Problem which is solved by the finite element Galerkin method and the minimum is computed by the conjugate gradient algorithm. We also present some numerical experiments. 相似文献
80.
Ana Porras Gutierrez Sophie Griveau Cyrille Richard Alain Pailleret Silvia Gutierrez Granados Fethi Bedioui 《Electroanalysis》2009,21(21):2303-2310
The elaboration of hybrid materials from single‐wall carbon nanotubes (SWCNT) and tetrasulfonated nickel phthalocyanine (NiTSPc) was electrochemically performed to obtain chemically modified electrodes with improved electrocatalytic activity towards the electrooxidation of nitric oxide (NO). The characterization of these hybrid electrodes was achieved by cyclic voltammetry and AFM. The electrochemical performances of the electrodes towards the oxidation of NO were then analyzed by chronoamperometry and the obtained results show that the presence of SWCNT greatly enhances the electrocatalytic performances in terms of current intensity. Additional coatings were then electrodeposited over the hybrid electrodes to act as selective membranes against four major interfering analytes: nitrite, ascorbate, hydrogen peroxide and L ‐arginine. Several polymer coatings were tested to achieve the best balance between sensitivity to NO and selectivity against interferents. 相似文献