We provide stabilizing and tracking feedback control laws for the kinematic system of an underactuated axisymmetric spacecraft subject to input constraints. As a special case we also provide a feedback control to track a specified direction in inertial space. All proposed control laws achieve asymptotic stability with exponential convergence. One of the novelties of the proposed control design ...

We present a combined Direct Numerical Simulation and Hot Wire Anemometry study of an axisymmetric turbulent wake. The data lead to a revised theory of axisymmetric turbulent wakes which relies on the mean streamwise momentum and turbulent kinetic energy equations, self-similarity of the mean flow, turbulent kinetic energy, Reynolds shear stress and turbulent dissipation profiles, non-equilibri...

We used computer simulations to study spontaneous strain localization in granular materials, as a result of symmetry breaking non-homogeneous deformations. Axisymmetric triaxial shear tests were simulated by means of standard three-dimensional Distinct Element Method (DEM) with spherical grains. Carefully prepared dense specimens were compressed between two platens and, in order to mimic the ex...

We have analysed the axisymmetric and non-axisymmetric modes of a continuum of vortices in a rotating superfluid. We have investigated how changing the temperature affects the growth rate of the disturbances. We find that, in the long axial wavelength limit the condition q = α/(1 − α) = 1, where α and α are temperature-dependent mutual friction parameters, is the crossover between damped and pr...

In many active stars the spots concentrate on two permanent active longitudes which are 180◦ apart. In some of these stars the dominant part of the spot activity changes the longitude every few years. This so-called flip-flop phenomenon has up to now been reported in 11 stars, both single and binary alike, and including also the Sun. To explain this phenomenon, a non-axisymmetric dynamo mode, g...

It is well known that most PDE problems defined over an axisymmetric domain can be efficiently solved by a Fourier based solution method. However, for many applications, the underlying computational domain is not entirely axisymmetric, but has one or several major axisymmetric subdomains. For such problems, an axisymmetric analysis method is not applicable, and a straightforward one can be inef...

Ground observatory and satellite-based determinations of temporal variations in the geomagnetic field probe a decadal to annual time scale range where Earth's core slow, inertialess convective motions rapidly propagating, inertia-bearing hydromagnetic waves are interplay. Here we numerically model jointly investigate these two important features with help geodynamo simulation that (to date) is ...

Using the fluid-magnetofluid formalism, we obtain axisymmetric stability criteria for a composite disc system consisting of stellar and gaseous magnetized singular isothermal discs (MSIDs). Both (M)SIDs are presumed to be razor-thin and are gravitationally coupled in a self-consistent axisymmetric background equilibrium with power-law surface mass densities and flat rotation curves. The gaseous...