Boundedness properties for time-varying homogeneous systems

A Liapunov theorem is introduced guaranteeing uniform boundedness and uniform ultimate boundedness for a timevarying nonlinear system _ x(t) = f(x(t); t). The study of uniform boundedness and uniform ultimate boundedness of particular classes of time-varying nonlinear systems _ x(t) = f(x(t); t) is reduced to the study of the corresponding timeinvariant frozen systems _ x(t) = f(x(t); ) for all 2 R. This approach is valid for time-varying homogeneous systems with positive order.