Centripetal instabilities in two flows involving time-dependent Rayleigh layers on a rotating circular cylinder are examined. In one case we consider the stability of the flow induced in an infinite expanse of quiescent fluid when the cylinder is impulsively given a constant angular velocity; in the other problem the angular velocity increases as the square root of time so that the undisturbed ...

This paper presents a novel methodology for the calculation of angular indexes an electrical system from stationary analysis, using load flow and nose curves (P–V) in each buses to perform control actions preserve or improve voltage stability. The are proposed considering method based on concepts cutset angle (CA) center (COA). target is fast estimation voltage-stability margins through appropr...

We aimed to determine if visual feedback use during aerial skills is more efficient at low angular head velocity (AHV; i.e., <350 deg/s) than at high AHV. Twelve experienced female acrobats performed 20 back tuck somersaults under four experimental conditions: full-vision (FV), vision at AHV below 350 deg/s (VBelow), vision at AHV above 350 deg/s (VAbove), and no-vision (NV). AHV was calculated...

In this research, samples of AlMg0.7Si aluminum alloy are deformed up to three passes using equal channel angular pressing (ECAP). Formation of a sub-micron structure after three passes of ECAP is demonstrated. Microstructural stability of the samples is investigated at temperatures of 300-500 &deg;C. At 300 &deg;C, fine recrystallized structure forms after 10 min which remains stable when the ...

A sequence of zero-temperature black-hole spacetimes with angular momentum and electric and magnetic charges is shown to exist in gauged N = 2 supergravity. Stability of a subset of these spacetimes is demonstrated by saturation of the Bogomol’nyi bound arising from the supersymmetry algebra. The mass of the resulting solitonic black holes is given in terms of the cosmological constant and the ...

A novel microwave metamaterial absorber design is introduced along with its manufacturing and characterization. Significant results considering both bandwidth and angular stability are achieved. Parametric analysis and simplified equivalent circuit are provided to give an insight on the key elements influencing the absorber performance. In addition, the constitutive parameters of the effective ...

This paper addresses attitude coordination control for spacecraft formation with multiple delays. A distributed angular velocity input law is firstly constructed for attitude synchronization and tracking under multiple communication delays. Introducing virtual auxiliary systems makes it possible to integrate the angular velocity input law with the true true control torque, and asymptotic stabil...

There has been much interest over the past decade in the problem of asymptotic stabilization of the angular velocity of a rigid body with only two torque inputs. The smooth feedback laws proposed in the literature provide asymptotic stability with nonexponential convergence rates. This paper proposes discontinuous feedback laws to achieve asymptotic stability with exponential convergence rates.