Axisymmetric stability of viscous resistive magnetized Couette flow is re-examined, with emphasis on flows that would be hydrodynamically stable according Rayleigh’s criterion: opposing gradients of angular velocity and specific angular momentum. In this regime, magnetorotational instability (MRI) may occur. The governing system in cylindrical coordinates is of tenth order. It is proved, by met...

This paper considers the problem of attitude synchronization control of a group of flexible spacecraft under an undirected communication graph and in the absence of measurements of both modal variables and spacecraft angular velocities. To solve this problem, a nonlinear observer is introduced to estimate the unmeasurable modal variables and spacecraft angular velocities. Then, the backstepping...

Spinning black three-branes in type IIB supergravity are thermodynamically stable up to a critical value of the angular momentum density. Inside the region of thermodynamic stability, the free energy from supergravity is roughly reproduced by a naive model based on free N = 4 super-Yang-Mills theory on the world-volume. The field theory model correctly predicts a limit on angular momentum densi...

We present preliminary results from a test beam run of CLEO III RICH modules. The system consists of LiF radiators and multiwire proportional chambers containing a mixture of CH4 and TEA gases. The radiators were both at and \sawtooth." The data were taken in a beam dump at Fermilab. We will discuss the chamber stability, electronics, the number of photons observed for both radiators, the angul...

We further investigate the runaway instability of relativistic tori around black holes assuming a power law distribution of the specific angular momentum. We neglect the self-gravity of the torus; thus the gravitational field of the system is determined by the central rotating black hole alone (the Kerr geometry). We find that for any positive (i.e. consistent with the local Rayleigh stability ...

We explore the structure and dynamics of dipolar Bose-Einstein condensates DBECs near their threshold for instability. Near this threshold a DBEC may exhibit nontrivial biconcave density distributions, which are associated with instability against collapse into “angular roton” modes. Here we discuss experimental signatures of these features. In the first, we infer local collapse of the DBEC fro...

This paper presents a design procedure for a reduced-order observer-based controller dedicated to n-joint robot manipulators. It is assumed that only the joint angular positions are measured. The joint angular velocities are estimated via an exponential reduced-order observer. Two types of control laws based on this observer are studied: point-to-point control with gravity compensation and traj...

In this paper, we study the dynamics of rotating Bose–Einstein condensates (BEC) based on the Gross–Pitaevskii equation (GPE) with an angular momentum rotation term and present an efficient and accurate algorithm for numerical simulations. We examine the conservation of the angular momentum expectation and the condensate width and analyze the dynamics of a stationary state with a shift in its c...

We investigate the suppression of the vibrations of a wind turbine tower using colocated feedback to achieve strong stability. We decompose the system into one model describing the vibrations in the plane of the turbine axis and another model in the plane of the turbine blades. In the plane of the turbine axis, we obtain a non-uniform Spacecraft Control Laboratory Experiment (SCOLE) model with ...