The Global Magnetorotational Instability (MRI) is investigated for a configuration in which the rotation frequency changes only in a narrow transition region. If the vertical wavelength of the unstable mode is of the same order or smaller than the width of this region, the growth rates can differ significantly from those given by a local analysis. In addition, the non-axisymmetric spectrum admi...

Perturbations of the Kerr black hole in the class of axisymmetric artificial black holes. Abstract Artificial black holes (called also acoustic or optical black holes) are the black holes for the linear wave equation describing the wave propagation in a moving medium. They attracted a considerable interest of physicists who study them to better understand the black holes in general relativity. ...

a simple new closed form of the green function for axisymmetric magnetostatic problemsis found analytically in cylindrical coordinates. the result is verified by applying several examples.

in this article, vehicle cornering stability and brake stabilization via bifurcation analysis has been investigated. in order to extract the governing equations of motion, a nonlinear four-wheeled vehicle model with two degrees of freedom has been developed. using the continuation software package matcont a stability analysis based on phase plane analysis and bifurcation of equilibrium is perfo...

In this chapter, we present some emerging directions in bifurcation control in continuous-time dynamical systems. Specifically we discuss two unconventional bifurcation control problems: anti-control of bifurcations and nonsmooth bifurcation control. Anti-control of bifurcation means introducing a new bifurcation at desired location with preferred properties by appropriate control. Nonsmooth bi...

Previous studies of the flow created inside a cylindrical cavity ~radius R , height H) of fluid by a single rotating end wall have shown that over a range of cylinder aspect ratios 1.6&H/R&2.8, the first unsteady flows to bifurcate with increasing Reynolds number retain axisymmetry, and subsequent bifurcations break axisymmetry to give solutions with modulated rotating wave ~MRW! states. The un...

Axisymmetric pulsations of rotating neutron stars can be excited in several scenarios, such as core-collapse, crust and core-quakes and binary mergers and could become detectable either in gravitational waves or high-energy radiation. Here, we present a comprehensive study of all low-order axisymmetric modes of uniformly and rapidly rotating relativistic stars. Initial stationary configurations...

We study event horizons of non-axisymmetric black holes and show how features found in axisymmetric studies of colliding black holes and of toroidal black holes are non-generic and how new features emerge. Most of the details of black hole formation and black hole merger are known only in the axisymmetric case, in which numerical evolution has successfully produced dynamical space-times. The wo...

We study stationary and axisymmetric solutions of General Relativity, i.e. pure gravity, in four or higher dimensions. D-dimensional stationary and axisymmetric solutions are defined as having D−2 commuting Killing vector fields. We derive a canonical form of the metric for such solutions that effectively reduces the Einstein equations to a differential equation on an axisymmetric D − 2 by D − ...