Search results for "Nonlinear"
showing 10 items of 3684 documents
Implementation of compact VLSI FitzHugh-Nagumo neurons
2008
In this paper we show a low power and very compact VLSI implementation of a FitzHugh-Nagumo neuron for large network implementations. The circuit consists of only 17 small transistors and two capacitors and consumes less than 23 muW. It is composed of a nonlinear resistor and a lossy active inductor. We demonstrate that a simple low Q active inductor can be used instead of a complex one because the parasitic series resistor can be easily embedded to the FitzHugh-Nagumo model. We also perform a statistical analysis to check the robustness of the circuit against mismatch.
Nonlinear vibrations of elastic beams with external general visco-elastic devices
2011
Vibration damping for slender beams is achieved by applying devices at external points. The latter consist of general single visco-elastic springpot elements. An approximate nonlinear boundary value problem is found in frequency domain that holds for moderately large vibrations or for linear beams with external nonlinear devices, both in the vicinity of primary resonances. The interaction force of a so-called springpot element is expressed as a sum of two separate forces: the first develops due to the external loading function at the device location, and the second contribution arises due to an imposed time-harmonic support excitation with no other external forces acting on the structure. F…
Creep Modeling with Time-Dependent Damping Parameters in Piezoelectric Actuators
2019
This paper develops a creep model based on the Kelvin-Voigt model with time varying damping parameters. In the piezoelectric actuators, the creep phenomenon is an important issue in precise positioning applications as well as the hysteresis property. It is well-known that the creep effect can be represented by a series connection of a number of Kelvin-Voigt elements as a viscoelastic model. In the motion for the continuous stepwise positioning, however, the creep shape is different for each response. Since the phenomenon can be captured as temporal creep relaxation, time-dependent damping parameters are introduced to improve the reproducibility of the creep for the various motion. On the ot…
Vibrations and oscillations of tri-soliton molecules in a mode-locked fiber laser
2018
We present numerical simulations highlighting internal oscillations and vibrations within tri-soliton molecules generated by a mode-locked fiber laser. We highlight major qualitative differences as compared to two-soliton molecules.
Asymptotic observer of the link states of flexible joint robots with motor-side sensing
2015
This paper proposes an approach for observing the link states, i.e. angular position and velocity, of the robotic joints with elasticities, when only the motor-side sensing is available. By separating the state-dependent nonlinearities of the rigid manipulator dynamics a linear sub-model of the elastic joint robot is obtained in an observable state-space form. The standard asymptotic Luenberger state observer is then designed for the given motor position signal which is measured by encoder and rectified from the nonlinear contribution. The configurable poles of observer allow shaping the estimated states dynamics to be fast enough in relation to the actual resonant joint behavior. Therefore…
Resonance phenomena in a nonlinear neuronal circuit
2015
International audience; We characterizes a nonlinear circuit driven by a bichromatic excitation,that is the sum of two sinusoidal waves with different frequencies f1 and f2 suchthat f2 > f1. Our experiments are confirmed by a numerical analysis of the systemresponse obtained by solving numerically the differential equations which rule thecircuit voltages. Especially, we highlight that the response of the system at the lowfrequency can be optimized by the amplitude of the high frequency. By revisiting thiswell known vibrational resonance effect in the whole amplitude frequency parametricplane, we show experimentally and numerically that a much better resonance can beachieved when the two fre…
Vibrational Resonance in inhomogeneous and space-dependent nonlinear damped systems
2020
International audience; The properties of nonlinear systems have attracted a considerable interest these past years since they can be used to develop bio-inspired applications ranging from signal detection to image processing. Among these nonlinear signatures is Vibrational Resonance (V.R.) which expresses the ability of a nonlinear system to take benefit of a high frequency perturbation in order to enhance its response to a weak low frequency excitation . Since its introduction in mechanical systems and electronic devices, this effect has been widely reported in various systems and for different applications. Indeed, V.R can be used to detect subthreshold signals or to enhance the percepti…
Noise contribution to resonance phenomena and information propagation in non linear electronic networks
2015
This manuscript presents research aiming to show possible positive effects of deterministic and stochastic perturbations on the responses of different nonlinear systems. To that end, both numerical and experimental studies were carried out on two kinds of structures : an elementary electronic FitzHugh-Nagumo oscillator and an electrical line developed by resistively coupling 45 elementary cells. In the first section, the elementary cell characterization was undertaken in a deterministic regime. In the presence of a bichromatic stimulus, it is shown that when the low frequency component is subthreshold, its detection can be maximized for an optimal magnitude of the second component thanks to…
Observational constraints on inhomogeneous cosmological models without dark energy
2011
It has been proposed that the observed dark energy can be explained away by the effect of large-scale nonlinear inhomogeneities. In the present paper we discuss how observations constrain cosmological models featuring large voids. We start by considering Copernican models, in which the observer is not occupying a special position and homogeneity is preserved on a very large scale. We show how these models, at least in their current realizations, are constrained to give small, but perhaps not negligible in certain contexts, corrections to the cosmological observables. We then examine non-Copernican models, in which the observer is close to the center of a very large void. These models can gi…
Numerical study of blow-up in solutions to generalized Kadomtsev-Petviashvili equations
2013
We present a numerical study of solutions to the generalized Kadomtsev-Petviashvili equations with critical and supercritical nonlinearity for localized initial data with a single minimum and single maximum. In the cases with blow-up, we use a dynamic rescaling to identify the type of the singularity. We present a discussion of the observed blow-up scenarios.