Research Article A Novel Method for Solving Nonlinear Volterra Integro-Differential Equation Systems Mohammad Hossein Daliri Birjandi, Jafar Saberi-Nadjafi , and Asghar Ghorbani Department of Applied Mathematics, School of Mathematical Sciences, Ferdowsi University of Mashhad, Mashhad, Iran Correspondence should be addressed to Jafar Saberi-Nadjaf; najaf141@gmail.com Received 12 December 2017; Accepted 2 April 2018; Published 3 June 2018 Academic Editor: Patricia J. Y. Wong Copyright © 2018 Mohammad Hossein Daliri Birjandi et al. Tis 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 efcient iteration method is introduced and used for solving a type of system of nonlinear Volterra integro-diferential equations. Te scheme is based on a combination of the spectral collocation technique and the parametric iteration method. Tis method is easy to implement and requires no tedious computational work. Some numerical examples are presented to show the validity and efciency of the proposed method in comparison with the corresponding exact solutions. 1. Introduction Systems of integro-diferential equations and their solu- tions play a pivotal role in the felds of science, industrial mathematics, control theory of fnancial mathematics, and engineering [1–3]. Physical systems, such as biological appli- cations in population dynamics, and genetics where impulses arise naturally or are caused by control are modeled by a system of integro-diferential equations [4, 5]. Te initial value problem for a nonlinear system of integro-diferential equations were used to model the competition between tumor cells and the immune system [6]. In [7], two systems of specifc inhomogeneous integro-diferential equations are studied in order to examine the noise term phenomenon. Tus applications of numerical methods for solving these equations are attractive. Tis has led to a great deal of research in recent years with the use of numerical methods such as the variational iteration method [8], diferential transform method [9], Bezier curves method [10], radial basis function networks [11], biorthogonal systems [12], the block pulse functions method [13], and a collocation method in combina- tion with operational matrices of Bernstein polynomials [14]. Te parametric iteration method (PIM) is an analytic approximate method that provides the solution of linear and nonlinear problems as a sequence of iterations. In fact, the PIM as a fxed- point iteration method is a reconstruction of the variational iteration method. Since the implementation of the PIM generally leads to the calculation of unneeded terms, where more time is consumed in repeated calculations for series solutions, so to overcome these shortcomings, a useful improvement of the PIM was proposed in [15]. Te aim of this work is to present an efective algorithm, requiring no tedious computational work, based on the improved PIM and the spectral collocation technique to obtaining an accurate solution for the following system of Volterra integro-diferential equations as follows: ̇ ()= (, 1 (), 2 (),..., ()) +∫ 0 (,) ( 1 (), 2 (),..., ()), (0) = ( 0 ) , (1) for  = 1,..., and  ∈ [0,]. Te functions (, 1 (), 2 (),..., ()) are given real valued functions, (,), =1, 2,...,, are kernels of the integral equations, and ( 1 (), 2 (),..., ()) are linear or nonlinear functions of 1 (), 2 (),..., (). To demonstrate the utility of the proposed method, some examples of system of Volterra integro-diferential equations are given, which are solved using the established method. Te Hindawi Abstract and Applied Analysis Volume 2018, Article ID 3569139, 6 pages https://doi.org/10.1155/2018/3569139