### فهرست مطالب

• Volume:6 Issue:2, 2016
• تاریخ انتشار: 1395/07/06
• تعداد عناوین: 7
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In this paper, the dynamic behavior of an immunosuppressive infection model, speci_cally AIDS, is analyzed. We show through a simple mathematical model that a sigmoidal CTL response can lead to the occurrence of transcritical bifurcation. This condition usually occurs in immunode_ciency virus infections (such as AIDS infection) in which viruses attack immune cells CD4. Our results imply that the dynamic interactions between the CTL immune response and HIV infection are very complex and in the CTL response, dynamics can exist the stable regions and unstable regions. At the end of the paper, numerical simulations are presented to illustrate the main results.
Keywords: CTL response, HAM, TSP, Transcritical bifurcation
• Yousof Edrisi, Tabri, Mehrdad Lakestani, Aghileh Heydari Pages 17-38
This paper presents two numerical methods for solving the nonlinear constrained optimal control problems including quadratic performance index.
The methods are based upon linear B-spline functions. The properties of B-spline functions are presented. Two operational matrices of integration are introduced for related procedures. These matrices are then utilized to reduce the solution of the nonlinear constrained optimal control to a nonlinear programming one to which existing well-developed algorithms may be applied. Illustrative examples are included to demonstrate the validity and applicability of the presented techniques.
Keywords: Optimal control problem, Linear B, spline function, Integration matrix, Collocation method
• M. Zarebnia, Leila Shiri Pages 39-50
In this paper, sinc-collocation method is discussed to solve Volterra func tional integral equations with delay function (t). Also the existence and uniqueness of numerical solutions for these equations are provided. This method improves conventional results and achieves exponential convergence. Numerical results are included to confirm the efficiency and accuracy of the method.
Keywords: Volterra functional integral equations, delay function, sinc, collocation
• Touraj Nikazad, Mehdi Karimpour Pages 51-64
When applying the non-stationary simultaneous iterative methods for solving an ill-posed set of linear equations, the error usually initially decreases but after some iterations, depending on the amount of noise in the data, and the degree of ill-posedness, it starts to increase. This phenomenon is called semi-convergence. We study the semi-convergence behavior of the non-stationary simultaneous iterative methods and obtain an upper bound for data error (noise error). Based on this bound, we propose new ways to specify the relaxation parameters to control the semi-convergence. The performance of our strategies is shown by examples taken from tomographic imaging.
Keywords: Simultaneous iterative methods, Semi, convergence, Relaxation parameters, Tomographic imaging