排序方式: 共有31条查询结果,搜索用时 15 毫秒
21.
Henri-Jean Cristau Marc Taillefer Corinne Combes Seddik Boucida Francoise Plenat Mary McPartlin 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1)
Abstract We describe the synthesis of new cyclotritphosphazenes in which the phosphorus substituents are either free-rotating or rigid planar heterocyclic groups, through phosphorus-carbon bonds. 相似文献
22.
Seddik Khalloufi Milena Corredig Marcela Alexander 《Colloids and surfaces. B, Biointerfaces》2009,68(2):145-153
Diffusing wave spectroscopy (DWS) was used to investigate the behavior of flaxseed gums when added to WPI-stabilized emulsions. The effect of different concentrations (0–0.33% (w/v)) of flaxseed gum, derived from two seed varieties, namely Emerson and McDuff, was studied at acidic and neutral pH. At pH 7.0 and low gum concentrations the dynamic and spatial characteristics of the system remained unchanged. While at gum concentrations from 0.075% to 0.20% a rapid phase separation was observed, at higher concentrations phase separation was retarded because of the increased background viscosity slowing down the mobility of the emulsion droplets. At pH 3.5, the difference in overall electrical charge between the gum (negative) and the protein on the emulsion surface (positive) led to electrostatic interactions. While at low concentration of flaxseed gum the general characteristics of the emulsions were not significantly different, at intermediate concentrations, bridging flocculation occurred. When sufficient flaxseed gum was present, the emulsion droplets mobility was arrested in a gel-like state. In spite of the compositional differences in the ratio of acidic and neutral fraction between the two polysaccharides extracted from different seed varieties, at both values of pH the behavior of the emulsions after addition of the polysaccharide was comparable. 相似文献
23.
Ameur Seddik 《Proceedings of the American Mathematical Society》2001,129(10):3009-3015
Let be the algebra of all bounded operators on a complex Hilbert space and let be an invertible self-adjoint (or skew-symmetric) operator of . Corach-Porta-Recht proved that
The problem considered here is that of finding (i) some consequences of the Corach-Porta-Recht Inequality; (ii) a necessary condition (resp. necessary and sufficient condition, when for the invertible positive operators to satisfy the operator-norm inequality for all in ; (iii) a necessary and sufficient condition for the invertible operator in to satisfy
24.
Seddik Chacrone 《Potential Analysis》1993,2(2):131-136
In a harmonic space with the domination Axiom (axiom D), B. Fuglede [5] has introduced the sheaf property of the cones of the finely hyperharmonic functions (defined in the fine opens). In [7], [8], J. Luke, J. Malý and L. Zajíek have studied a notion analogous to the finely hyperharmonic functions without supposing axiom D, and have proved ([8] theorem 12.16) that if the cones of the positive finely hyperharmonic functions make a sheaf, then axiom D is satisfied. See N. Boboc, Gh. Bucur and A. Cornea [3] for the first result of this type given within the context of theH-cones.In this paper, we prove axiom D is a consequence of the sheaf property even for the smallest class of the functions (the class of the finely harmonic functions; absolute-value bounded in a convenient sense). This result implies that of Lukeet al. cited above. Consequently, the tow fine properties of the sheaf are equivalent, which has not been evident previously. 相似文献
25.
J. Sari F. Cremonesi M. Khalloufi F. Cauneau P. Meliga Y. Mesri E. Hachem 《国际流体数值方法杂志》2018,86(11):717-736
Aerodynamic characteristics of various geometries are predicted using a finite element formulation coupled with several numerical techniques to ensure stability and accuracy of the method. First, an edge‐based error estimator and anisotropic mesh adaptation are used to detect automatically all flow features under the constraint of a fixed number of elements, thus controlling the computational cost. A variational multiscale‐stabilized finite element method is used to solve the incompressible Navier‐Stokes equations. Finally, the Spalart‐Allmaras turbulence model is solved using the streamline upwind Petrov‐Galerkin method. This paper is meant to show that the combination of anisotropic unsteady mesh adaptation with stabilized finite element methods provides an adequate framework for solving turbulent flows at high Reynolds numbers. The proposed method was validated on several test cases by confrontation with literature of both numerical and experimental results, in terms of accuracy on the prediction of the drag and lift coefficients as well as their evolution in time for unsteady cases. 相似文献
26.
Ameur Seddik 《Journal of Mathematical Analysis and Applications》2009,351(1):277-1777
Let B(H) be the C*-algebra of all bounded linear operators acting on a complex Hilbert space H. In this note, we shall show that if S is an invertible normal operator in B(H) the following estimation holds
27.
Positivity - The aim of this paper is to study some properties of positive solutions to the nonlinear diffusion equation $$\begin{aligned} \frac{\partial u(x,t)}{\partial t} = \Delta _p u(x,t) +... 相似文献
28.
Seddik Ouakkas 《Differential Geometry and its Applications》2008,26(5):495-502
We consider harmonic semi-conformal maps between two Riemannian manifolds. By deforming conformally the codomain metric, we construct new examples of non-harmonic biharmonic maps. 相似文献
29.
Luca Placidi Ralf Greve Hakime Seddik Sérgio H. Faria 《Continuum Mechanics and Thermodynamics》2010,22(3):221-237
A complete theoretical presentation of the Continuum-mechanical, Anisotropic Flow model, based on an anisotropic Flow Enhancement
factor (CAFFE model) is given. The CAFFE model is an application of the theory of mixtures with continuous diversity for the
case of large polar ice masses in which induced anisotropy occurs. The anisotropic response of the polycrystalline ice is
described by a generalization of Glen’s flow law, based on a scalar anisotropic enhancement factor. The enhancement factor
depends on the orientation mass density, which is closely related to the orientation distribution function and describes the
distribution of grain orientations (fabric). Fabric evolution is governed by the orientation mass balance, which depends on
four distinct effects, interpreted as local rigid body rotation, grain rotation, rotation recrystallization (polygonization)
and grain boundary migration (migration recrystallization), respectively. It is proven that the flow law of the CAFFE model
is truly anisotropic despite the collinearity between the stress deviator and stretching tensors. 相似文献
30.
A. Seddik 《Integral Equations and Operator Theory》2002,43(2):248-252
For n-tuplesA=(A
1,...,A
n
) andB=(B
1,...,B
n
) of operators on a Hilbert spaceH, letR
A,B
denote the operator onL(H) defined by
. In this paper we prove that
whereW is the joint spatial numerical range andW
0 is the numerical range. We will show also that this inclusion becomes an equality whenR
A,B
is taken to be a generalized derivation, and it is strict whenR
A,B
is taken to be an elementary multiplication operator induced by non scalar self-adjoints operators. 相似文献