Research Article
An Optimal Method for Diffusion Parameters of
Nonlinear Diffusion Problem of Drug Releasing in
2D-Disc Device by Separate Variable Method
Youyun Li,
1,2
Jinhui Ouyang,
1
Jiaohua Qin,
3
and Yingli Gao
2
1
State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, Beijing 100038, China
2
College of Highway Engineering, Changsha University of Science and Technology, Hunan, 410004, China
3
College of Computer, Central South University of Forestry and Technology, Changsha 410004, China
Correspondence should be addressed to Youyun Li; liyouyun@hotmail.com
Received November ; Revised February ; Accepted February ; Published March
Academic Editor: Vassilios C. Loukopoulos
Copyright © Youyun Li et al. is is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
An optimization control model and the corresponding computational method drawing the diusion parameters of the nonlinear
problem for the drug releasing in the D-disc device were given in this paper. Firstly, based on the nonlinear diusion equation
of the drug releasing in the D-disc device, we used the linear diusion problem to discrete the nonlinear diusion problem with
the discrete space and the discrete time. en, by the separate variable method, the solution of the linear problem was given. Next,
the least square method based on the separate variable idea (LSMSV) was used to estimate the nonlinear appropriate diusion
parameters. Finally, a numerical example was presented to show that the control model and the numerical method were valid for
computing the diusion coecient of the nonlinear problem for the drug releasing in the D-disc device.
1. Introduction
In engineering elds, there exist many diusion processes in
many elds such as geomechanics engineering, biomedical
science, civil engineering, water pollution, and soil engi-
neering [–]. In order to simulate the diusion processes
to obtain their merits, it is important to draw the eective
diusiveness. ere are many models for the simulation of
the diusion processes. Most of them are the nonlinear or
linear models. For the linear models, most optimal control
problems governed by the diusion equations arose in many
scientic and engineering applications such as the water
pollution problems and the drug releasing elds [–]. ere
are many various techniques for the identication for the
eective diusiveness based on the linear models. ese tech-
niques are based on either empirical or semiempirical models
from drug delivery mechanisms or on analytic solutions of
thediusionequationinDorinthespecialcases[–
, , ].
However, in the practice application, many diusion
processes are subjected to the nonlinear partial dierential
equations [–]. In order to illustrate the nonlinear diusion
processes in many elds, many nonlinear models are applied
to estimate the properties. For many nonlinear diusion
elds, the diusion coecients are the functions of the
diusion concentration. erefore, computing the diusion
parameters is mainly to determinate the parameters of the
coecient function called the diusion parameters function.
e diusion parameter function of the concentration is con-
sidered as the main element to control the diusion processes.
erefore, many researches were given to determine the
parameter function to illustrate the diusion processes. Many
nonlinear optimal models drawing the diusion parameters
depended on both the lab technology and the shape of the
container [, , , ]. In order to compute the diusion
parameters, many scientists and mathematicians provided
some optimal methods to compute the diusion parameters
[, , ]. Most of them cost a lot of computing time and
Hindawi Publishing Corporation
Mathematical Problems in Engineering
Volume 2014, Article ID 796812, 8 pages
http://dx.doi.org/10.1155/2014/796812