2008 NOV 17 - (VerticalNews.com) -- "The perturbed rotational motion of a gyrostat about a fixed point with mass distribution near to Lagrange's case is investigated. The gyrostat is subjected under the influence of a variable restoring moment vector, a perturbing moment vector, and a third component of a gyrostatic moment vector," scientists writing in the journal Nonlinear Dynamics report.

  "It is assumed that the angular velocity of the gyrostat is sufficiently large, its direction is close to the axis of dynamic symmetry, and the perturbing moments are small as compared to the restoring ones. These assumptions permit us to introduce a small parameter. Averaged systems of the equations of motion in the first and second approximations are obtained. Also, the evolution of the precession angle up to the second approximation is determined," wrote T.S. Amer and colleagues, Tanta University ...read more

  2008 NOV 17 - (VerticalNews.com) -- According to recent research from Iran, "This paper introduces a fractional order system which can generate regular oscillations or create chaos. It shows that this system is capable to create regular or nonregular oscillations under suitable conditions."

  "These necessary conditions are achieved by violation of the no-chaos criteria. The effective dimension of the proposed system can be chosen any order less than three. Therefore, this system is a good example for limit cycle or chaos generation via fractional-order systems with low orders," wrote M.S. Tavazoei and colleagues ...read more

  2008 NOV 17 - (VerticalNews.com) -- "For the position tracking in DC motor with unknown bound time-varying dead zone uncertainties, a novel sliding mode adaptive controller is proposed by means of sliding mode and function approximation technique in this paper," scientists in Hefei, People's Republic of China report.

  "First, control law with an uncertain term and another compensative term is obtained using sliding mode technique, and then the function approximation technique is employed to transform the uncertain term into finite combinations of orthonormal basis functions. The concrete expressions of uncertain term and compensative term can thus be derived based on the Lyapunov design," wrote Y.Y. Liang and colleagues, China University ...read more