the release rate of potassium (k) from micaceous minerals plays a significant role in supplying k to plants. the objective of this study was to determine the most appropriate kinetic equation to describe potassium release from micaceous minerals as influenced by organic acids. muscovite and phlogopite were made to react with 0, 500, 2000 and 4000 ?m solutions of oxalic, citric and malic acids f...

the release of fe from soil solid phases into soil solution is a dynamic process that regulates the continuous supply of this element to growing plants. to ascertain the pattern of fe release, the kinetics of fe release from six soils by diethylenetriaminepentaacetic acid (dtpa) solution were investigated using soil samples taken from two different agroclimatic regions of iran. all soils were c...

The paper is concerned with Lp error analysis of semi-discrete Galerkin FEMs for nonlinear parabolic equations. The classical energy approach relies heavily on the strong regularity assumption of the diffusion coefficient, which may not be satisfied in many physical applications. Here we focus our attention on a general nonlinear parabolic equation (or system) in a convex polygon or polyhedron ...

A semi-Lagrangian method for parabolic problems is proposed, that extends previous work by the authors to achieve a fully conservative, flux-form discretization of linear and nonlinear diffusion equations. A basic consistency and convergence analysis are proposed. Numerical examples validate the proposed method and display its potential for consistent semi-Lagrangian discretization of advection...

We study a parabolic population model in the full space and prove the global in time existence of a weak solution. This model consists of two strongly coupled diffusion equations describing the population densities of two competing species. The system features intrinsic growth, interand intra-specific competition of the species, as well as diffusion, cross-diffusion and self-diffusion, and drif...

We study a parabolic population model in the full space and prove the global in time existence of a weak solution. This model consists of two strongly coupled diffusion equations describing the population densities of two competing species. The system features intrinsic growth, interand intra-specific competition of the species, as well as diffusion, cross-diffusion and self-diffusion, and drif...

The parabolic partial differential equation arises in many application of technologies. In this paper, we propose an approximate method for solution of the heat and advection-diffusion equations using Laguerre-Gaussians radial basis functions (LG-RBFs). The results of numerical experiments are compared with the other radial basis functions and the results of other schemes to confirm the validit...

We propose an approximation of the convection-diffusion operator which consists in the product of two parabolic operators. This approximation is much easier to solve than the full convection-diffusion equation, which is elliptic in space. We prove that this approximation is of order three in the viscosity and that the classical parabolic approximation is of order one in the viscosity. Numerical...