Title  Stability and bifurcation analysis of reactiondiffusion systems with delays 
Author  Hu, Rui 
Description  Thesis (Ph.D.)Memorial University of Newfoundland, 2010. Mathematics and Statistics 
Date  2009 
Pagination  iv, 138 leaves : ill. 
Subject  Bifurcation theory; Delay differential equations; Differential equations, Partial; Reactiondiffusion equations 
Degree  Ph.D. 
Degree Grantor  Memorial University of Newfoundland. Dept. of Mathematics and Statistics

Discipline  Mathematics and Statistics

Language  Eng 
Notes  Bibliography: leaves 130138. 
Abstract  The work focuses on the stability of steady state and local bifurcation analysis in partial differential equations with different delays. Especially, a neural network model with discrete delay and diffusion is proposed in the first part; a diffusive competition model with uniformly distributed delay is studied in part 2. An extended reactiondiffusion system with general distributed delay is treated in part 3. In the last part, a Nicholson's blowflies model with nonlocal delay and diffusion is discussed.  For a diffusive neural network model with discrete delay, by analyzing the distributions of the eigenvalues of the system and applying the center manifold theory and normal form computation, we show that, regarding the connection coefficients as the perturbation parameter, the system, with different boundary conditions, undergoes some bifurcations including transcritical bifurcation, Hopf bifurcation and Hopfzero bifurcation. The normal forms are given to determine the stabilities of the bifurcated solutions.  In some cases, the model with distributed delay is more accurate than that with discrete delay. We study a competition diffusion system with uniformly distributed delay. The complete analysis of the characteristic equation is given. And via the analysis, the stability of the constructed positive spatially nonhomogeneous steady state solution is obtained. Moreover, the occurrence of Hopf bifurcation near the steady state solution is proved by using the implicit function theorem with time delay as the bifurcation parameter. Finally, the formula determining the stability of the periodic solutions is given.  The uniformly distributed kernel is only one of the widely used time kernel. It is natural to discuss more general time kernels. We consider a class of reactiondiffusion system with general kernel functions. The stability of the constructed positive spatially nonhomogeneous steady state solution is obtained under general kernels by using the similar method in part 2. Moreover, taking minimal time delay as the bifurcation parameter, we can not only show the existence of Hopf bifurcations near the steady state solution, but also prove that the Hopf bifurcation is forward and the bifurcated periodic solutions are stable under certain condition. The general results are applied to competitive and cooperative systems with weak kernel function.  In many application models, if individuals move, it is more reasonable to model delay and diffusion simultaneously, which induces nonlocal delay by employing Britton's random walk method. We study the stability of the uniform steady states and Hopf bifurcation of diffusive Nicholson's blowflies equation with nonlocal delay. By using the upper and lower solutions method, we have obtained the global stability conditions at the constant steady states, and discussed the local stability. Moreover, for a special kernel, we have proved the occurrence of Hopf bifurcation near the steady state solution and given formula in determining stability of bifurcated periodic solutions. 
Type  Text 
Resource Type  Electronic thesis or dissertation 
Format  Image/jpeg; Application/pdf 
Source  Paper copy kept in the Centre for Newfoundland Studies, Memorial University Libraries 
Local Identifier  a3315355 
Rights  The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. 
Collection  Electronic Theses and Dissertations 
Scanning Status  Completed 
PDF File  (11.83 MB)  http://collections.mun.ca/PDFs/theses/Hu_Rui.pdf 
CONTENTdm file name  10181.cpd 