Suppression and Excitation of Chaos: The Example of the Glow Discharge

1998 ◽  
Vol 08 (08) ◽  
pp. 1739-1742 ◽  
Author(s):  
Thomas Braun
Keyword(s):  
Dynamical System ◽  
Glow Discharge ◽  
Numerical Simulations ◽  
Experimental Observation ◽  
Logistic Map ◽  
Dynamical Variable ◽  
Time Dependent ◽  
External Signal ◽  
Controlling Chaos ◽  
Suppression Of Chaos

I report on the experimental observation of excitation and suppression of chaos through time dependent perturbations in the dynamical variable of a glow discharge. The interaction of the external signal with the dynamical system is explained in terms of the 1D map associated to the glow discharge. Numerical simulations are also performed with the logistic map. The proposed mechanism of exciting and/or suppressing chaos is in accordance with the OGY method of controlling chaos.

Controlling Chaos with Parametric Perturbations

1998 ◽  
Vol 08 (08) ◽  
pp. 1693-1698 ◽  
Author(s):  
Leone Fronzoni ◽  
Michele Giocondo
Keyword(s):  
Dynamical System ◽  
Liquid Crystal ◽  
Dynamical Systems ◽  
Electronic Device ◽  
Parametric Perturbation ◽  
Mechanical Device ◽  
Controlling Chaos ◽  
Onset Of Chaos ◽  
Spatio Temporal ◽  
Suppression Of Chaos

We consider the effects of parametric perturbation on the onset of chaos in different dynamical systems. Favoring or suppression of chaos was observed depending on the phase or the frequency of the periodic perturbation. A lowering of the threshold of chaos was observed in an electronic device simulating a Josephson-Junction model and the suppression of chaos was obtained in a bistable mechanical device. We showed that in case of spatial instability in a sample of liquid crystal, the action of the parametric perturbation is to modify the velocity and the onset of the defects. Considering that the emergence of defects precedes the threshold of spatio-temporal chaos, we infer that parametric perturbation can modify the threshold of chaos in this spatial dynamical system.

On Techniques Towards Chaos Preservation and Construction

2017 ◽  
Vol 27 (12) ◽  
pp. 1750191
Author(s):  
Qiang Jia
Keyword(s):  
Dynamical System ◽  
Numerical Simulations ◽  
Chaotic System ◽  
General Framework ◽  
Chaotic Systems ◽  
Time Dependent ◽  
System Construction ◽  
State Dependent

This paper provides a general framework for modifying chaotic systems on the premise of preserving chaos. It formulates effective techniques to construct some derivative systems from an existing chaotic system by replacing a parameter or a term in the dynamical system with certain time-dependent or state-dependent functions. This study derives an alternative for chaotic system construction and also provides more flexibility for chaotic synthesis. Numerical simulations demonstrate the effectiveness and validity of the proposed techniques. As a consequence, some new chaotic systems are also obtained.

Flow Mixing Enhancement from Balloon Pulsations in an Intravenous Oxygenator

2004 ◽  
Vol 127 (3) ◽  
pp. 400-415 ◽  
Author(s):  
Amador M. Guzmán ◽  
Rodrigo A. Escobar ◽  
Cristina H. Amon
Keyword(s):  
Numerical Simulations ◽  
Oxygen Transfer ◽  
Fiber Bundle ◽  
Transfer Rate ◽  
Oxygen Transfer Rate ◽  
Three Dimensional ◽  
Time Dependent ◽  
Fiber Placement ◽  
Flow Mixing ◽  
Dependent Flow

Computational investigations of flow mixing and oxygen transfer characteristics in an intravenous membrane oxygenator (IMO) are performed by direct numerical simulations of the conservation of mass, momentum, and species equations. Three-dimensional computational models are developed to investigate flow-mixing and oxygen-transfer characteristics for stationary and pulsating balloons, using the spectral element method. For a stationary balloon, the effect of the fiber placement within the fiber bundle and the number of fiber rings is investigated. In a pulsating balloon, the flow mixing characteristics are determined and the oxygen transfer rate is evaluated. For a stationary balloon, numerical simulations show two well-defined flow patterns that depend on the region of the IMO device. Successive increases of the Reynolds number raise the longitudinal velocity without creating secondary flow. This characteristic is not affected by staggered or non-staggered fiber placement within the fiber bundle. For a pulsating balloon, the flow mixing is enhanced by generating a three-dimensional time-dependent flow characterized by oscillatory radial, pulsatile longitudinal, and both oscillatory and random tangential velocities. This three-dimensional flow increases the flow mixing due to an active time-dependent secondary flow, particularly around the fibers. Analytical models show the fiber bundle placement effect on the pressure gradient and flow pattern. The oxygen transport from the fiber surface to the mean flow is due to a dominant radial diffusion mechanism, for the stationary balloon. The oxygen transfer rate reaches an asymptotic behavior at relatively low Reynolds numbers. For a pulsating balloon, the time-dependent oxygen-concentration field resembles the oscillatory and wavy nature of the time-dependent flow. Sherwood number evaluations demonstrate that balloon pulsations enhance the oxygen transfer rate, even for smaller flow rates.

On Controlling Chaos in an Inflation–Unemployment Dynamical System

1999 ◽  
Vol 10 (9) ◽  
pp. 1567-1570 ◽  
Author(s):  
E. Ahmed ◽  
H ◽  
A. El-misiery ◽  
H.N. Agiza
Keyword(s):  
Dynamical System ◽  
Controlling Chaos

A New Time-dependent Theory of Tropical Cyclone Intensification

2021 ◽  
Author(s):  
Yuqing Wang ◽  
Yuanlong Li ◽  
Jing Xu
Keyword(s):  
Boundary Layer ◽  
Tropical Cyclone ◽  
Numerical Simulations ◽  
Strong Dependence ◽  
Surface Wind ◽  
Time Dependent ◽  
Quasi Equilibrium ◽  
Free Atmosphere ◽  
Near Surface ◽  
Tangential Wind

AbstractIn this study, the boundary-layer tangential wind budget equation following the radius of maximum wind, together with an assumed thermodynamical quasi-equilibrium boundary layer is used to derive a new equation for tropical cyclone (TC) intensification rate (IR). A TC is assumed to be axisymmetric in thermal wind balance with eyewall convection becoming in moist slantwise neutrality in the free atmosphere above the boundary layer as the storm intensifies as found recently based on idealized numerical simulations. An ad-hoc parameter is introduced to measure the degree of congruence of the absolute angular momentum and the entropy surfaces. The new IR equation is evaluated using results from idealized ensemble full-physics axisymmetric numerical simulations. Results show that the new IR equation can reproduce the time evolution of the simulated TC intensity. The new IR equation indicates a strong dependence of IR on both TC intensity and the corresponding maximum potential intensity (MPI). A new finding is the dependence of TC IR on the square of the MPI in terms of the near-surface wind speed for any given relative intensity. Results from some numerical integrations of the new IR equation also suggest the finite-amplitude nature of TC genesis. In addition, the new IR theory is also supported by some preliminary results based on best-track TC data over the North Atlantic and eastern and western North Pacific. Compared with the available time-dependent theories of TC intensification, the new IR equation can provide a realistic intensity-dependent IR during weak intensity stage as in observations.

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