الفهرس 
Chapter 1 IntroductionOnly 14 pages are availabe for public view
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Abstract
In study of nonlinear partial differential equations (PDEs), finding exact solutions has great theoretical and practical importance. The thesis focus on soliton solutions and exact solu- tions for some nonlinear (PDEs) using some analytical methods that have been introduced recently in order to solve nonlinear (PDEs) which represent some physically relevant sys- tems in applied physics and applied mathematics . This thesis includes six main chapters organized as follows:
Chapter one contains basic concepts and consists of two sections. First section is the exact wave solution and a brief history of soliton theory and some examples of soliton types. The second section outlines the main steps of the methods used in the thesis.
In chapter two, Jacobi elliptic function expansion method is applied to secure optical soliton solutions in magneto-optic wave guides for coupled system of nonlinear Biswas- Milovic equation with Kudryashov’s law of refractive index. The solutions obtained are bright soliton solutions, dark soliton solutions, singular-bright combo soliton solutions, pe- riodic solutions and jacobi elliptic solutions. To aid in a complete understanding of the solutions acquired for the studied system, graphical representations of some extracted so- lutions are provided.
In chapter three, we give a wide account of bright solitons and periodic solutions for twin-core couplers and multiple-core couplers with polynomial law of non-linearity and nonlinear perturbation terms using the Jacobi elliptic function expansion method. The restrictions on the parameters are considered to guarantee the existence of the obtained solitons. Moreover, graphs of some solutions are presented to show their features.
In chapter four, we have dealt with a set of three mathematical models, namely non- linear Schro¨dinger’s equation, Lakshmanan - Porsezian - Daniel model, and Sasa-Satsuma model, which is called the concatenation model. The study investigates optical solitons and other exact solutions using a modified extended mapping approach. The study considers constraints on the parameters to ensure the existence of the obtained soliton solutions.
In chapter five, the modified extended mapping method is used to discover new soliton solutions and other solutions to the (4+1)-dimensional Davey-Stewartson- Kadomtsev - Petviashvili (DSKP) equation. Through this chapter, we discover a variety of new solu- tions, including (bright, dark and singular, combo dark-singular soliton solution, singular periodic and periodic solution).
Chapter six is devoted for studying the presence of the wave soliton solutions for a new two-component LPD system. The improved modified extended tanh-function method is employed to obtain diverse soliton solutions and other exact solutions for the given sys- tem. The results demonstrate the rich variety of soliton solutions that can be obtained using this system, and the graphical representations of selected solutions provide a clear picture of their physical nature.