2026/9/8

Roushanak Lotfikar

Academic rank: Assistant Professor
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Education: PhD.
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Faculty: Basic Science
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Research

Title
Discretization Based on a Nystrom Method for Approximating the Solution of Second-Kind Mixed Volterra-Fredholm Integral Equations
Type
Thesis
Keywords
Weakly singular Volterra integral equation, Galerkin method, Iterated Galerkin method, Piecewise polynomial approximation, Mixed-type kernel, Graded mesh.
Year
2026
Researchers Athir Jumaa Khalaf(Student)، Roushanak Lotfikar(PrimaryAdvisor)

Abstract

In this thesis, numerical solution techniques for solving second-kind mixed Volterra-Fredholm integral equations featuring algebraic endpoint singularities is presented. Building upon the Nystr\"{o}m method, we develop and analyze a discretization scheme that combines Gauss-Jacobi quadrature for the Fredholm part with product integration rules for the weakly singular Volterra component. The analysis is carried out in weighted Banach spaces $C_u$ equipped with Jacobi-type weights, which naturally accommodate the low regularity of solutions near the endpoints. Under mild smoothness assumptions on the kernels and right-hand side, we establish stability, convergence, and error estimates that are of the order of the best polynomial approximation in $C_u$. The theoretical framework is supported by existence and uniqueness results based on fixed-point theorems, and numerical experiments confirm the high accuracy of the proposed method.