DYNAMICAL SYSTEMS WITH VARIABLE DISSIPATION: APPROACHES, METHODS, AND APPLICATIONS

摘要

This work is devoted to the development of qualitative methods in the theory of nonconser-vative systems that arise, e.g., in such fields of science as the dynamics of a rigid body interacting with a resisting medium, oscillation theory, etc. This material can arouse the interest of specialists in the qualitative theory of ordinary differential equations, in rigid body dynamics, as well as in fluid and gas dynamics since the work uses the properties of motion of a rigid body in a medium under streamline flow-around conditions.rnThe author obtains a full spectrum of complete integrability cases for nonconservative dynamical systems having nontrivial symmetries. Moreover, in almost all cases of integrability, each of the first integrals is expressed through a finite combination of elementary functions and is a transcendental function of its variables, simultaneously. In this case, the transcendence is meant in the complex analysis sense; i.e., after the continuation of the functions considered to the complex domain, they have essentially singular points. The latter fact is stipulated by the existence of attracting and repelling limit sets in the system considered (for example, attracting and repelling foci).rnThe author obtains new families of phase portraits of systems with variable dissipation on lower-and higher-dimensional manifolds. He discusses the problems of their absolute or relative roughness, He discovers new integrable cases of rigid body motion, including those in the classical problem of motion of a spherical pendulum placed in an over-running medium flow.