This paper establishes a direct method for solving variational problems via a set of Radial basis functions (RBFs) with Gauss-Chebyshev collocation centers. The method consist of reducing a variational problem into a mathematical programming problem. The authors use some optimization techniques to solve the reduced problem. Accuracy and stability of the multiquadric, Gaussian and inverse multiq...

Nanocrystalline ZnO particles were prepared by a novel sonochemical route from zinc acetate and sodium hydroxide without any requirement of calcination steps at high temperature and without surfactants. Variations in several parameters and their effects on the structural (crystal size and morphology) properties of nanoparticles were investigated. Characterizations were carried out by X-Ray ...

nanocrystalline zno particles were prepared by a novel sonochemical route from zinc acetate and sodium hydroxide without any requirement of calcination steps at high temperature and without surfactants. variations in several parameters and their effects on the structural (crystal size and morphology) properties of nanoparticles were investigated. characterizations were carried out by x-ray diff...

we describe how to obtain electronic transport properties of disordered graphene, including the tight binding model and nearest neighbor hopping. we present a new method for computing, electronic transport wave function and greens function of the disordered graphene. in this method, based on the small rectangular approximation, break up the potential barriers in to small parts. then using the f...

effect of water gas shift reaction (co+h2o=co2+h2) on wustite reduction has been investigated by a transient, non-isothermal mathematical model based on grain model. in this model, wustite porous pellet is reduced using syngas, namely a mixture of hydrogen, carbon monoxide, carbon dioxide and water vapor. for this purpose, governing equations containing continuity equation of species and energy...

We propose a method for the direct inversion of the permeability field of a porous medium from the analysis of the displacement of a passive tracer. By monitoring the displacement front at successive time intervals (for example, using a tomographic method), the permeability can be directly obtained from the solution of a nonlinear boundary-value problem. Well posedness requires knowledge of the...

In this paper, using the direct method we study the generalized Hyers-Ulam-Rassias stability of the following quadratic functional equations (2 ) ( ) 6 ( )     f x y f x y f x and (3 ) ( ) 16 ( )     f x y f x y f x for the mapping f from normed linear space in to 2-Banach spaces.

this research study employed a mixed-methods approach to investigate the test takers’ perceptions and anx- iety in relation to an english language proficiency test called community english program (cep). this study also evaluated the direct and semi-direct modes for speaking module of this test. to this end, 300 eng- lish as foreign language (efl) students were recruited in the study as test ta...