149 research outputs found
Optimum PID Control of Multi-wing Attractors in A Family of Lorenz-like Chaotic Systems
Multi-wing chaotic attractors are highly complex nonlinear dynamical systems
with higher number of index-2 equilibrium points. Due to the presence of
several equilibrium points, randomness of the state time series for these
multi-wing chaotic systems is higher than that of the conventional double wing
chaotic attractors. A real coded Genetic Algorithm (GA) based global
optimization framework has been presented in this paper, to design optimum PID
controllers so as to control the state trajectories of three different
multi-wing Lorenz like chaotic systems viz. Lu, Rucklidge and Sprott-1 system.Comment: 6 pages, 21 figures; 2012 Third International Conference on
Computing, Communication and Networking Technologies (ICCCNT'12), July 2012,
Coimbator
Shadow of Kottler black hole in the presence of plasma for a co-moving observer
We consider a spherically symmetric black hole metric in (3+1)-dimensions in
presence of a positive cosmological constant . We use a general
approach as proposed in \cite{1} to transform the metric in co-moving
coordinates. Then for a general metric we have evaluated the angular shadow
size both in absence and presence of plasma. By using the aberration relation,
we then find the corresponding shadow radius as viewed by a co-moving observer
for Schwarzschild de-Sitter or Kottler spacetime. The effect of cosmological
constant and plasma parameter on the angular size of black hole
shadow has been observed in detail. Finally, by using the observed angular size
of M87 black hole, we constrain the value of the plasma parameter with
a specific observational value of the cosmological constant (or the
Hubble constant ).Comment: 21 pages, 12 figures, comments are welcom
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