scholarly journals Switch Elements with S-Shaped Current-Voltage Characteristic in Models of Neural Oscillators

Electronics ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 922 ◽  
Author(s):  
Petr Boriskov ◽  
Andrei Velichko
Keyword(s):  
Piecewise Linear ◽  
Differential Resistance ◽  
Practical Significance ◽  
Piecewise Linear Approximation ◽  
Type I ◽  
Current Voltage ◽  
Oscillation Modes ◽  
Temperature Dependences ◽  
Switch Element ◽  
Machine Interface

In this paper, we present circuit solutions based on a switch element with the S-type I–V characteristic implemented using the classic FitzHugh–Nagumo and FitzHugh–Rinzel models. Using the proposed simplified electrical circuits allows the modeling of the integrate-and-fire neuron and burst oscillation modes with the emulation of the mammalian cold receptor patterns. The circuits were studied using the experimental I–V characteristic of an NbO2 switch with a stable section of negative differential resistance (NDR) and a VO2 switch with an unstable NDR, considering the temperature dependences of the threshold characteristics. The results are relevant for modern neuroelectronics and have practical significance for the introduction of the neurodynamic models in circuit design and the brain–machine interface. The proposed systems of differential equations with the piecewise linear approximation of the S-type I–V characteristic may be of scientific interest for further analytical and numerical research and development of neural networks with artificial intelligence.

scholarly journals Method for the fuzzy control system synthesis for the analytical approximation characteristics of the typical nonlinear elements characteristics

2020 ◽  
Vol 224 ◽  
pp. 01013
Author(s):  
V Lubentsov ◽  
E Shakhrai ◽  
E Lubentsova
Keyword(s):  
Control System ◽  
Fuzzy Controller ◽  
Piecewise Linear ◽  
Continuous Functions ◽  
Analytical Approximation ◽  
Practical Significance ◽  
Piecewise Linear Approximation ◽  
Static Mode ◽  
System Synthesis ◽  
Control System Synthesis

The solution of the problem concerning the control system synthesis with a fuzzy controller on the basis of typical nonlinear analytical approximation characteristics with continuous differentiable functions like sigmoid type has been considered. A method of synthesis which is based on the fact that the rulebase and membership function are formed by the way of comparing the control or corrective impacts of the fuzzy controller (prototype) or a controller with approximating control (CAC) has been suggested for problem solving. For the CAC construction the closest coincidence of graphically installed controllers’ impacts are taken. This makes it possible to exclude subjective errors connecting with a possible non-representative ruleset for the rulebase forming. The result of the work is to obtain a new class of controllers based on the approximating continuous functions, which are simpler for constructing multi-mode control systems. The practical significance lies in the fact, that the tuning of the fuzzy controller based on the analytical continuous approximation of the typical nonlinear elements’ characteristics comes down to two basic parameters: the coefficient that determines the curvature (slope) of the characteristic in the transit mode and the parameter that determines the control impact value in the static mode. The advantage of this smooth characteristic in relation to the piecewise linear approximation is that there is no need to determine the moments (points) of switching nonlinear characteristics during the system operation.

scholarly journals Actor-critic learning-based energy optimization for UAV access and backhaul networks

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Yaxiong Yuan ◽  
Lei Lei ◽  
Thang X. Vu ◽  
Symeon Chatzinotas ◽  
Sumei Sun ◽  
...  
Keyword(s):  
Power Allocation ◽  
Heuristic Algorithms ◽  
Piecewise Linear ◽  
Access Network ◽  
Computation Time ◽  
Combinatorial Problem ◽  
Base Station ◽  
Piecewise Linear Approximation ◽  
Group Scheduling ◽  
User Group

AbstractIn unmanned aerial vehicle (UAV)-assisted networks, UAV acts as an aerial base station which acquires the requested data via backhaul link and then serves ground users (GUs) through an access network. In this paper, we investigate an energy minimization problem with a limited power supply for both backhaul and access links. The difficulties for solving such a non-convex and combinatorial problem lie at the high computational complexity/time. In solution development, we consider the approaches from both actor-critic deep reinforcement learning (AC-DRL) and optimization perspectives. First, two offline non-learning algorithms, i.e., an optimal and a heuristic algorithms, based on piecewise linear approximation and relaxation are developed as benchmarks. Second, toward real-time decision-making, we improve the conventional AC-DRL and propose two learning schemes: AC-based user group scheduling and backhaul power allocation (ACGP), and joint AC-based user group scheduling and optimization-based backhaul power allocation (ACGOP). Numerical results show that the computation time of both ACGP and ACGOP is reduced tenfold to hundredfold compared to the offline approaches, and ACGOP is better than ACGP in energy savings. The results also verify the superiority of proposed learning solutions in terms of guaranteeing the feasibility and minimizing the system energy compared to the conventional AC-DRL.

CHUA’S CIRCUIT: AN OVERVIEW TEN YEARS LATER

1994 ◽  
Vol 04 (02) ◽  
pp. 117-159 ◽  
Author(s):  
LEON O. CHUA
Keyword(s):  
Secure Communication ◽  
Vector Fields ◽  
Piecewise Linear ◽  
International Workshop ◽  
Noise Spectrum ◽  
Chaotic Regime ◽  
Practical Significance ◽  
Chua’S Circuit ◽  
Chua's Circuit ◽  
New Phenomena

More than 200 papers, two special issues (Journal of Circuits, Systems, and Computers, March, June, 1993, and IEEE Trans. on Circuits and Systems, vol. 40, no. 10, October, 1993), an International Workshop on Chua’s Circuit: chaotic phenomena and applica tions at NOLTA’93, and a book (edited by R.N. Madan, World Scientific, 1993) on Chua’s circuit have been published since its inception a decade ago. This review paper attempts to present an overview of these timely publications, almost all within the last six months, and to identify four milestones of this very active research area. An important milestone is the recent fabrication of a monolithic Chua’s circuit. The robustness of this IC chip demonstrates that an array of Chua’s circuits can also be fabricated into a monolithic chip, thereby opening the floodgate to many unconventional applications in information technology, synergetics, and even music. The second milestone is the recent global unfolding of Chua’s circuit, obtained by adding a linear resistor in series with the inductor to obtain a canonical Chua’s circuit— now generally referred to as Chua’s oscillator. This circuit is most significant because it is structurally the simplest (it contains only 6 circuit elements) but dynamically the most complex among all nonlinear circuits and systems described by a 21-parameter family of continuous odd-symmetric piecewise-linear vector fields. The third milestone is the recent discovery of several important new phenomena in Chua’s circuits, e.g., stochastic resonance, chaos-chaos type intermittency, 1/f noise spectrum, etc. These new phenomena could have far-reaching theoretical and practical significance. The fourth milestone is the theoretical and experimental demonstration that Chua’s circuit can be easily controlled from a chaotic regime to a prescribed periodic or constant orbit, or it can be synchronized with 2 or more identical Chua’s circuits, operating in an oscillatory, or a chaotic regime. These recent breakthroughs have ushered in a new era where chaos is deliberately created and exploited for unconventional applications, e.g. secure communication.

CHARGE TRANSPORT THROUGH CARBON NANOTUBE OR FULLERENE–MOLECULE–SILICON JUNCTIONS

NANO ◽  
2007 ◽  
Vol 02 (05) ◽  
pp. 285-294
Author(s):  
FU-REN F. FAN ◽  
BO CHEN ◽  
AUSTEN K. FLATT ◽  
JAMES M. TOUR ◽  
ALLEN J. BARD
Keyword(s):  
Carbon Nanotube ◽  
Charge Transport ◽  
Electron Acceptor ◽  
Negative Differential Resistance ◽  
Fullerene Molecule ◽  
Differential Resistance ◽  
Electron Donors ◽  
Switching Behavior ◽  
Current Voltage ◽  
Bistable Switching

We report here the current–voltage (i–V) characteristics of several (n++- Si /MNOPE/ C 60/ Pt -tip) or (n++- Si /MNOPE/SWCNT/ Pt -tip) junctions, where MNOPE = 2'-mononitro-4, 4'-bis(phenylethynyl)-1-phenylenediazonium and SWCNT = single wall carbon nanotube. A layer of C 60 or SWCNT-derivatized MNOPE has strong effect on the i–V behavior of the junctions, including rectification, negative differential resistance (NDR) and switching behaviors. The i–V curve of a grafted molecular monolayer (GMM) of MNOPE atop n++- Si shows NDR behavior, whereas those of C 60- and SWCNT-derivatized GMMs of MNOPE on n++- Si show strong rectifying behavior with opposite rectification polarities. With C 60, larger currents were found with negative tip bias, while with SWCNT, the forward top bias was positive. Because C 60 tends to be a good electron acceptor and SWCNTs tend to be good electron donors, they show different i–V behavior, as observed. Some of the (n++- Si /MNOPE/SWCNT/ Pt -tip) junctions also show reversible bistable switching behavior.

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