17 research outputs found
Minimal Universal Model for Chaos in Laser with Feedback
No full textInternational audienceWe revisit the model of the laser with feedback and the minimal nonlinearity leading to chaos. Although the model has its origin in laser physics, with peculiarities related to the [Formula: see text] laser, it belongs to the class of the three-dimensional paradigmatic nonlinear oscillator models giving chaos. The proposed model contains three key nonlinearities, two of which are of the type [Formula: see text], where [Formula: see text] and [Formula: see text] are the fast and slow variables. The third one is of the type [Formula: see text], where [Formula: see text] is an intermediate feedback variable. We analytically demonstrate that it is essential for producing chaos via local or global homoclinic bifurcations. Its electronic implementation in the range of kilo Hertz region confirms its potential in describing phenomena evolving on different time scales
Torus Breakdown in a Uni Junction Memristor
No full textInternational audienceExperimental study of a uni junction transistor (UJT) has enabled to show that this electronic component has the same features as the so-called “memristor”. So, we have used the memristor’s direct current (DC) vM–iM characteristic for modeling the UJT’s DC current–voltage characteristic. This has led us to confirm on the one hand, that the UJT is a memristor and, on the other hand, to propose a new four-dimensional autonomous dynamical system allowing to describe experimentally observed phenomena such as the transition from a limit cycle to torus breakdown
Jerk Dynamics in the Minimal Universal Model of Laser
No full textIn a previous publication, we established a new paradigmatic model of laser with feedback including the minimal nonlinearity leading to chaos. In this paper, the jerk dynamics of this minimal universal model of laser is presented. It is proved that two equivalent forms of the model in jerk dynamics can be derived. The electronic circuit of the simpler dynamics is designed and implemented. The link between the minimal universal model of laser and the search for simple jerk circuits is established
Identification of minimal parameters for optimal suppression of chaos in dissipative driven systems
Get PDFTaming chaos arising from dissipative non-autonomous nonlinear systems by applying additional harmonic excitations is a reliable and widely used procedure nowadays. But the suppressory effectiveness of generic non-harmonic periodic excitations continues to be a significant challenge both to our theoretical understanding and in practical applications. Here we show how the effectiveness of generic suppressory excitations is optimally enhanced when the impulse transmitted by them (time integral over two consecutive zeros) is judiciously controlled in a not obvious way. Specifically, the effective amplitude of the suppressory excitation is minimal when the impulse transmitted is maximum. Also, by lowering the impulse transmitted one obtains larger regularization areas in the initial phase difference-amplitude control plane, the price to be paid being the requirement of larger amplitudes. These two remarkable features, which constitute our definition of optimum control, are demonstrated experimentally by means of an analog version of a paradigmatic model, and confirmed numerically by simulations of such a damped driven system including the presence of noise. Our theoretical analysis shows that the controlling effect of varying the impulse is due to a subsequent variation of the energy transmitted by the suppressory excitation.P.J.M. and R.C. acknowledge financial support from the Ministerio de Economía y Competitividad (MINECO, Spain) through FIS2011-25167 and FIS2012-34902 projects, respectively. R.C. acknowledges financial support from the Junta de Extremadura (JEx, Spain) through project GR15146. J.A.C.G. was supported by CNPq, Brazil.Peer reviewe
A physical memristor based Muthuswamy–Chua–Ginoux system
No full textInternational audienceIn 1976, Leon Chua showed that a thermistor can be modeled as a memristive device. Starting from this statement we designed a circuit that has four circuit elements: a linear passive inductor, a linear passive capacitor, a nonlinear resistor and a thermistor, that is, a nonlinear "locally active" memristor. Thus, the purpose of this work was to use a physical memristor, the thermistor, in a Muthuswamy-Chua chaotic system (circuit) instead of memristor emulators. Such circuit has been modeled by a new three-dimensional autonomous dynamical system exhibiting very particular properties such as the transition from torus breakdown to chaos. Then, mathematical analysis and detailed numerical investigations have enabled to establish that such a transition corresponds to the so-called route to Shilnikov spiral chaos but gives rise to a "double spiral attractor". Michael Faraday (1791-1867) is generally well known for his contributions to the study of electromagnetism and electrochemistry. However, according to Orton 1 , while investigating the effect of temperature on the conductivity of "sulphuret of silver" (silver sulfide) in 1833 he discovered what is now considered as a thermistor 2. Thermistor, i.e., thermal resistor, is thus an electrical-resistance element made of a semiconducting material the resistance of which varies with temperature. Thermistor production was then difficult, and applications were limited. One century had to pass before thermistors became commonly used by commercial manufacturers. In the 1930s, Samuel Ruben (1900-1988) invented the first commercial thermistor that he called "electrical pyrometer resistance" (Patents N o 2,021,491). He explained that: This invention relates to an electrical pyrometer and specifically to one utilizing the resistance change of a metallic compound with heat to indicate temperature changes. The characteristic property of the material employed for the temperature indicating resistance element is one having a high negative resistance coefficient
