# Arunas TamaseviciusCenter for Physical Sciences and Technology | CPST · Department of Electronics

Arunas Tamasevicius

Dr. Habil.

## About

261

Publications

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Introduction

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Education

September 1968 - June 1975

## Publications

Publications (261)

We describe an implementation of an electronic feedback controller, destroying synchrony and/or suppressing the mean field in arrays of globally coupled nonidentical oscillators. We demonstrate that the mean field, either artificially nullified or fed back into the array with a negative sign can break up the phase synchronization. The experiments h...

An adaptive feedback technique for stabilizing a priori unknown saddle steady states of dynamical systems is described. The method is based on an unstable low-pass filter combined with a stable low-pass filter. The cutoff frequencies of both filters can be set relatively high. This allows considerable increase in the rate of convergence to the stea...

An adaptive feedback method for tracking and stabilizing unknown and/or slowly varying saddle-type steady states of conservative and weakly damped dissipative dynamical systems is proposed. We demonstrate that a conservative saddle point can be stabilized with neither unstable nor stable filter technique. The proposed controller involves both filte...

A feedback method for stabilizing the steady states in an array of the coupled nonlinear oscillators is described. The method employs two complementary techniques: the pinning control accomplished via a single accidentally accessed (or randomly chosen) oscillator and the repulsive mean field. Analytical, numerical, and experimental results are pres...

Stabilization of the fixed points in globally coupled nonlinear oscillators is described. The method combines two control techniques, (1) the pinning technique implemented via single accidentally accessed or randomly chosen oscillator and (2) the repulsive coupling technique introduced by the inverted mean field in the feedback loop. Analytical, nu...

A technique for stabilizing the steady states in an array of either the star coupled or the all-to-all coupled FitzHugh–Nagumo (FHN) oscillators is described. To control the whole array a single oscillator or a small fraction of the oscillators can be involved. The controller is a four-terminal device and includes an external active nonlinear oscil...

Two control methods for stabilization of the steady states of the globally coupled second-order oscillators via local feedback are described. The first technique is based on the proportional feedback with a constant adjustable reference. The second technique is an adaptive one, employing the first-order stable filter. Three different types of oscil...

A control method for desynchronizing an array of mean-field coupled FitzHugh–Nagumo-type oscillators is described. The technique is based on applying an adjustable DC voltage source to the coupling node. Both, numerical solution of corresponding nonlinear differential equations and hardware experiments with a nonlinear electrical circuit have been...

An array of globally all-to-all coupled FitzHugh-Nagumo–type oscillators is considered. We suggest an adaptive first-order stable filter control feedback technique to stabilize the steady states of the oscillators. The overall system includes separate networks of coupling and control. Therefore, the controller does not depend on the intrinsic param...

A control method for desynchronizing an array of N mean-field coupled modified FitzHugh–Nagumo oscillators is described. The technique is based on filtering the mean field sampled at the coupling node. The first order branched RC filter is composed of N coupling resistors and a single capacitor. The technique can be applied to arrays in a wide rang...

We suggest employing the first-order stable RC filters, based on a single capacitor, for control of unstable fixed points in an array of oscillators. A single capacitor is sufficient to stabilize an entire array, if the oscillators are coupled strongly enough. An array, composed of 24 to 30 mean-field coupled FitzHugh–Nagumo (FHN) type asymmetric o...

Damping of spikes in an array of coupled oscillators by injection of sinusoidal current is studied both electronically and numerically. The effect is investigated using an array consisting of thirty mean-field coupled FitzHugh–Nagumo-type oscillators. The results are considered as a possible mechanism of the deep brain stimulation used to avoid the...

Extremely high 'excess noise ratio' of 80 dB is observed from an avalanche transistor circuit, operating in a random pulse mode. Broadband noise spectrum measured from 30 MHz to 1 GHz exhibits good flatness with the nonuniformity of only +/- 1 dB. Experiments have been performed with the silicon bipolar junction microwave transistors. An analog cir...

An analog circuit, based on a negative impedance converter and a capacitor, for damping oscillations in an array of
mean-field coupled neuronal FitzHugh–Nagumo (FHN) type oscillators is described. The circuit is essentially a two-terminal feedback controller. When coupled to an array of the FHN oscillators, it stabilizes their unstable steady state...

A tutorial discussion of negative resistance oscillators based on simple RLC circuits is presented. Two cases are
based on parallel RLC circuits and two cases are based on series RLC circuits. Distortion is minimized by introducing symmetry in the movement of the complex pole-pair of the small signal model.

An adaptive feedback method for stabilizing unknown saddle- type steady states of dynamical systems is described. Many other techniques developed so far use unstable linear filters to track and control the saddles. In contrast, the novel controller is an essentially nonlinear unit. It implements the Heaviside step function (piecewise constant funct...

An extremely simple analog technique for desynchronization of neuronal FitzHugh-Nagumo-type oscillators is described. Two-terminal feedback circuit has been developed. The feedback circuit, when coupled to a network of oscillators, nullifies the voltage at the coupling node and thus effectively decouples the individual oscillators. Both numerical s...

An adaptive controller for stabilization of unknown unstable steady
states (spirals, nodes and saddles) of nonlinear dynamical systems is
considered and its robustness under the changes of the location of the
fixed point in the phase space is demonstrated. An analog electronic
controller, based on a low-pass filter technique, is described. It can
b...

A synergetic control technique for stabilizing a priori unknown saddle steady states of dynamical systems is described. The method involves an unstable filter technique combined with a derivative feedback. The cut-off frequency of the filter is not limited by the damping of the system, and therefore can be set relatively high. This essentially incr...

An analog technique for desynchronisation of FitzHugh-Nagumo type oscillators is described. Two-terminal feedback controller is applied to the network. The controller nullifies the voltage at the coupling node and effectively decouples the individual oscillators. Both, numerical simulations and hardware experiments are performed. The results for ar...

A simple zero-order proportional feedback technique for stabilizing unknown fixed points is described. The technique employs either artificially created or natural stable fixed point to find the coordinates of the unknown unstable fixed point. Four physical examples have been investigated, namely the mechanical pendulum, the autonomous Duffing damp...

A simple zero-order proportional feedback technique for stabilizing unknown fixed points is described. The technique employs either artificially created or natural stable fixed point to find the coordinates of the unknown unstable fixed point. Four physical examples have been investigated, namely the mechanical pendulum, the autonomous Duffing damp...

The purpose of the paper is to show that analogue electronic modelling is an extremely fast technique compared to conventional digital computing, especially when solving large sets of coupled nonlinear differential equations. An array of thirty FitzHugh-Nagumo type electronic oscillators, modelling dynamics of the brain neurons, is considered. The...

The purpose of the paper is to show that analogue electronic modelling is an extremely fast technique compared to conventional digital computing, especially when solving large sets of coupled nonlinear differential equations. An array of thirty FitzHugh–Nagumo type electronic oscillators, modelling dynamics of the brain neurons, is considered. The...

A novel Silva-Young type fourth-order autonomous chaotic oscillator is described. In comparison with the original nonautonomous Silva-Young circuit it lacks the external periodic driving oscillator, but includes a passive internal second-order resonant LRC circuit, inserted in the positive feedback loop. In contrast to many other nonautonomous and...

Simple analog electrical circuit representing complex dynamical system is described. As case study an array of thirty FitzHugh-Nagumo coupled electronic oscillators, imitating dynamics of neurons, is considered. Due to the parallel processing analog simulation exhibits very fast performance compared with the numerical integration.

A higher-order oscillator, including a nonlinear unit and an 8th-order low-pass active Bessel filter is described. The Bessel unit plays the role of "three-in-one": a delay line, an amplifier and a filter. Results of hardware experiments and numerical simulation are presented. Depending on the parameters of the nonlinear unit the oscillator operate...

An improvement of the recently described resonant chaos control method is suggested. Negative feedback loop containing a notch-rejection filter, tuned to the main harmonic of the unstable periodic orbit, is supplemented with a set of notch filters tuned to the higher harmonics. The extended method is applied to an electrical circuit representing th...

A tutorial study of an oscillator built from a loop of two active RC integrators and an ideal inverter. As a reference the linear harmonic oscillator is modeled as a LC circuit and as an ideal two integrator loop. The nonlinear amplifiers of the active RC integrator circuits are assumed to be linear with time varying gain and the eigenvalues are fo...

A novel Duffing-Holmes type autonomous chaotic oscillator is described. In comparison with the well-known nonautonomous Duffing-Holmes circuit it lacks the external periodic drive, but includes two extra linear feedback subcircuits, namely a direct positive feedback loop, and an inertial negative feedback loop. In contrast to many other autonomous...

A FitzHugh–Nagumo type spiking neuron model equipped with an asymmetric activation function is investigated. An analogue nonlinear
electrical circuit imitating the dynamics of the model is proposed. It is demonstrated that a simple first order linear filter
coupled to the system can inhibit spiking and stabilize the system on an unstable steady sta...

An extremely simple first order RC high-pass filter is suggested to suppress harmful radio frequency oscillations, induced by high power electromagnetic pulses. Specifically, a broadband single stage transistor amplifier with a parasitic wiring inductance and also the parasitic junction and mounting capacitances are investigated both numerically an...

A novel Duffing-Holmes type autonomous chaotic oscillator is described. In comparison with the well-known nonautonomous Duffing-Holmes circuit it lacks the external periodic drive, but includes two extra linear feedback subcircuits, namely a direct positive feedback loop, and an inertial negative feedback loop. In contrast to many other autonomous...

An extremely simple first order RC high-pass filter is suggested to suppress harmful radio frequency oscillations , induced by high power electromagnetic pulses. Specifically, a broadband single stage transistor amplifier with a parasitic wiring inductance and also the parasitic junction and mounting capacitances are investigated both numerically a...

We demonstrate that a dynamical system can be switched from a stable steady state to a previously unknown unstable (saddle) steady state using proportional feedback coupling to an auxiliary unstable system. The simplest one-dimensional nonlinear model is treated analytically, the more complicated two-dimensional pendulum is considered numerically,...

A tutorial study of the Colpitts oscillator family defined as all oscillators based on a nonlinear amplifier and a three-terminal linear resonance circuit with one coil and two capacitors. The original patents are investigated. The eigenvalues of the linearized Jacobian for oscillators based on single transistors or operational amplifiers are studi...

We demonstrate both experimentally and numerically that slow recovery p - n junction diodes can be exploited to generate chaos at high megahertz frequencies. An extremely simple resonator consisting of an inductor in parallel with a diode when externally periodically driven exhibits chaotic response.

We describe an extremely simple second order analogue electrical circuit for simulating the two-well Duffing-Holmes mathematical oscillator. Numerical results and analogue electrical simulations are illustrated with the snapshots of chaotic waveforms, with the phase portraits (the Lissajous figures) and with the stroboscopic maps (the Poincaré sect...

We describe an extremely simple second order analogue electrical circuit for simulating the two-well Duffing-Holmes mathematical oscil lator. Numerical results and analogue electrical simulations are illustrated with the s napshots of chaotic waveforms, with the phase portraits (the Lissajous figures) and with the stroboscopic maps (the Poincare se...

We demonstrate that a dynamical system can be switched from a stable steady state to a previously unknown unstable saddle steady state using proportional feedback coupling to an auxiliary unstable system. The simplest one-dimensional nonlinear model is treated analytically, the more complicated two-dimensional pendulum is considered numerically, wh...

Signal prediction method employing basis of time-delayed functions is considered. Corresponding analog processing circuit is designed and investigated by means of PSPICE type simulator. Performance of the predictor using the BFG520 microwave transistors is demonstrated for frequencies up to 1000 MHz.

A mathematical model of a recently suggested chaos oscillator for educational purposes is treated and numerical results are presented. Bifurcation diagrams, phase portraits, power spectra, Lyapunov exponents are simulated. In addition, the Feigenbaum number is estimated.

Nonvanishing N-shaped nonlinear function has been introduced in delay dynamical system instead of commonly used Mackey-Glass type function. Depending on time delay the system exhibits not only mono-scroll, but also more complex two-scroll hyperchaotic attractors. Delay system with the novel nonlinear function can be implemented as an analogue elect...

A novel version of chaotic Colpitts oscillator is described. Instead of a linear loss resistor, it includes an extra inductor and a diode in the collector circuit of the transistor. The modified circuit in comparison with the common Colpitts oscillator may generate chaotic oscillations at the fundamental frequency f * noticeably closer to the thres...