177 research outputs found
Observation of chaotic beats in a driven memristive Chua's circuit
In this paper, a time varying resistive circuit realising the action of an
active three segment piecewise linear flux controlled memristor is proposed.
Using this as the nonlinearity, a driven Chua's circuit is implemented. The
phenomenon of chaotic beats in this circuit is observed for a suitable choice
of parameters. The memristor acts as a chaotically time varying resistor
(CTVR), switching between a less conductive OFF state and a more conductive ON
state. This chaotic switching is governed by the dynamics of the driven Chua's
circuit of which the memristor is an integral part. The occurrence of beats is
essentially due to the interaction of the memristor aided self oscillations of
the circuit and the external driving sinusoidal forcing. Upon slight
tuning/detuning of the frequencies of the memristor switching and that of the
external force, constructive and destructive interferences occur leading to
revivals and collapses in amplitudes of the circuit variables, which we refer
as chaotic beats. Numerical simulations and Multisim modelling as well as
statistical analyses have been carried out to observe as well as to understand
and verify the mechanism leading to chaotic beats.Comment: 30 pages, 16 figures; Submitted to IJB
Antimonotonicity, Crisis and Multiple Attractors in a Simple Memristive Circuit
Peer reviewedPostprin
Colpitts Chaotic Oscillator Coupling with a Generalized Memristor
By introducing a generalized memristor into a fourth-order Colpitts chaotic oscillator, a new memristive Colpitts chaotic oscillator is proposed in this paper. The generalized memristor is equivalent to a diode bridge cascaded with a first-order parallel RC filter. Chaotic attractors of the oscillator are numerically revealed from the mathematical model and experimentally captured from the physical circuit. The dynamics of the memristive Colpitts chaotic oscillator is investigated both theoretically and numerically, from which it can be found that the oscillator has a unique equilibrium point and displays complex nonlinear phenomena
The Fourth Element: Characteristics, Modelling, and Electromagnetic Theory of the Memristor
In 2008, researchers at HP Labs published a paper in {\it Nature} reporting
the realisation of a new basic circuit element that completes the missing link
between charge and flux-linkage, which was postulated by Leon Chua in 1971. The
HP memristor is based on a nanometer scale TiO thin-film, containing a
doped region and an undoped region. Further to proposed applications of
memristors in artificial biological systems and nonvolatile RAM (NVRAM), they
also enable reconfigurable nanoelectronics. Moreover, memristors provide new
paradigms in application specific integrated circuits (ASICs) and field
programmable gate arrays (FPGAs). A significant reduction in area with an
unprecedented memory capacity and device density are the potential advantages
of memristors for Integrated Circuits (ICs). This work reviews the memristor
and provides mathematical and SPICE models for memristors. Insight into the
memristor device is given via recalling the quasi-static expansion of Maxwell's
equations. We also review Chua's arguments based on electromagnetic theory.Comment: 28 pages, 14 figures, Accepted as a regular paper - the Proceedings
of Royal Society
Phenomenology of retained refractoriness: On semi-memristive discrete media
We study two-dimensional cellular automata, each cell takes three states:
resting, excited and refractory. A resting cell excites if number of excited
neighbours lies in a certain interval (excitation interval). An excited cell
become refractory independently on states of its neighbours. A refractory cell
returns to a resting state only if the number of excited neighbours belong to
recovery interval. The model is an excitable cellular automaton abstraction of
a spatially extended semi-memristive medium where a cell's resting state
symbolises low-resistance and refractory state high-resistance. The medium is
semi-memristive because only transition from high- to low-resistance is
controlled by density of local excitation. We present phenomenological
classification of the automata behaviour for all possible excitation intervals
and recovery intervals. We describe eleven classes of cellular automata with
retained refractoriness based on criteria of space-filling ratio, morphological
and generative diversity, and types of travelling localisations
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