Showing 3 results for Stability
Azim Aminataei,
Volume 13, Issue 3 (11-2013)
Abstract
In this study, we simulate numerically the process of oxygen mass transport in the human circulatory system incorporating the contribution of axial diffusion. Simulated equation is a time dependent convective-diffusion partial differential equation wherein has applicable application in the bioengineering problems such as boundary layer of fluids, electrical circuits in cables and mass transport problems.
The analytical solution of this kind of equations is complicated. Therefore, the numerical solution for obtaining the approximate solution is important and the convergence and stability in this method of solution, is always a question. In this study, we try to answer the above questions with respect to this special equation and for this we use finite differences.
, Ehsan Mir Mehrabi,
Volume 17, Issue 40 (9-2015)
Abstract
Fractional derivatives and integrals are new concepts of derivatives and integrals of arbitrary order. Partial differential equations whose derivatives can be of fractional order, are called fractional partial differential equations (FPDEs). Recently, these equations have been under special attentions due to their most practical usages. In this paper, we survey a rather general case of FPDE, to obtain a numerical scheme, the fractional derivatives in the equation are replaced by common definitions such as Grundwald-Letnikov, Riemann-Liouville and Caputo, to improve the numerical solution, partial derivatives inside the equation are discrete using non-standard finite difference scheme. Then, we survey the stability of numerical scheme and prove that the proposed method is unconditionally stable. Eventually, in order to approve the theoretical results, we use presented technique to solve wave equation with fractional-order that is very practical and widely used in physics and its branches. Numerical results confirm the findings of the theory and show that this technique is effective.
Volume 18, Issue 45 (6-2008)
Abstract
The stability constants of 1:1 complexes formed between M2+ : Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+ , Cd2+ and the thymidine-5’-diphosphate (dTDP3-) were determined by potentiometric pH titration in aqueous solution (I= 0.1 M, NaNO3 25°C). For comparison, the same values were used the simple diphosphates monoesters (R-DP3-). The acidity constants for dTDP3- i.e. و و were measured also via potentiometric pH titration and various comparisons with related constants were made. By constraction of log versus p plots for the complexes of the diphosphates and by a carful evaluation of the various data pairs from the straight-line correlation, the results show that in the M(dTDP)-- complexes the points lie on the line and the metal ion is only diphosphate-coordinated. This means that there is no interaction between suger and nucleoside base with metal ion. The straight line equations, which result from the mentioned correlations, together with the pKa value of a given monoprotonated diphosphate monoester allow now to predict the stability constants of M(R-DP)--complexes.
