In this manuscript we introduce some important concepts concerning dynamical systems theory. We devote special attention to studying differential equations from a dynamical systems viewpoint. The introduced concepts are illustrated by examples.

The aim of this work is to describe the qualitative behavior of the solution set of a given system of fractional differential equations and limiting behavior of the dynamical system or flow defined by the system of fractional differential equations. In order to achieve this goal, it is first necessary to develop the local theory for fractional nonlinear systems. This is done by the extension of...

in this paper a new form of the homptopy perturbation method is used for solving oscillator differential equation, which yields the maclaurin series of the exact solution. nonlinear vibration problems and differential equation oscillations have crucial importance in all areas of science and engineering. these equations equip a significant mathematical model for dynamical systems. the accuracy o...

In some aerospace vehicles, the tracking sensors which act in a tracking loop as stabilizer are mounted on a two degree of freedom gyro. The gyro must align its rotor axis with the line of sight in order to remove tracking errors. The tracking precision and sensitivity are functions of the gyros performance. One of the main factors in reducing the precision and producing instabilities is nutati...

In this article, an improved reduced order modelling approach, based on the proper orthogonal decomposition (POD) method, is presented. After projecting the governing equations of flow dynamics along the POD modes, a dynamical system was obtained. Normally, the classical reduced order models do not predict accurate time variations of flow variables due to some reasons. The response of the dynam...

In this paper we aim to analyse the stability of two dynamical systems given by differential equations or by systems of differential equations. The first model is a mechanical system which is described by a system of differential equations of the first degree. We study the stability of this system using the method of the Lyapunov function. The second studied model is the model of a vibrant tool...

A new approach using optimization technique for constructing low-dimensional dynamical systems of nonlinear partial differential equations (PDEs) is presented. After the spatial basis functions of the nonlinear PDEs are chosen, spatial basis functions expansions combined with weighted residual methods are used for time/space separation and truncation to obtain a high-dimensional dynamical syste...

Quasi-linear differential-algebraic equations (DAEs) are essential tools for modeling dynamical processes, e.g. for mechanical systems, electrical circuits or chemical reactions. These models are in general of higher index and contain so called hidden constraints which lead to instabilities and order reductions during numerical integration of the model equations. In this article we consider dyn...

the effect of weak shear thickening and shear thinning on the stability of the taylor-couette flow is explored for a carreau-bird fluid in the narrow-gap limit. the galerkin projection method is used to derive a low-order dynamical system from the conservation of mass and momentum equations. in comparison with the newtonian system, the present equations include additional nonlinear coupling in ...