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219 results on '"Tesi, Alberto"'

2. Physical Implementation of a Tunable Memristor-based Chua's Circuit

Author

Escudero, Manuel, Spiga, Sabina, di Marco, Mauro, Forti, Mauro, Innocenti, Giacomo, Tesi, Alberto, Corinto, Fernando, and Brivio, Stefano

Subjects
Computer Science - Emerging Technologies
Abstract

Nonlinearity is a central feature in demanding computing applications that aim to deal with tasks such as optimization or classification. Furthermore, the consensus is that nonlinearity should not be only exploited at the algorithm level, but also at the physical level by finding devices that incorporate desired nonlinear features to physically implement energy, area and/or time efficient computing applications. Chaotic oscillators are one type of system powered by nonlinearity, which can be used for computing purposes. In this work we present a physical implementation of a tunable Chua's circuit in which the nonlinear part is based on a nonvolatile memristive device. Device characterization and circuit analysis serve as guidelines to design the circuit and results prove the possibility to tune the circuit oscillatory response by electrically programming the device., Comment: Accepted by IEEE 48th European Solid State Circuits Conference (ESSCIRC 2022)

Published
2023
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3. A small-gain theorem for 2-contraction of nonlinear interconnected systems

Author

Angeli, David, Martini, Davide, Innocenti, Giacomo, and Tesi, Alberto

Subjects
Electrical Engineering and Systems Science - Systems and Control
Abstract

This paper introduces small-gain sufficient conditions for $2$-contraction of feedback interconnected systems, on the basis of individual gains of suitable subsystems arising from a modular decomposition of the second additive compound equation. The condition applies even to cases when individual subsystems might fail to be contractive (due to the extra margin of contraction afforded by the second additive compound matrix). Examples of application are provided to illustrate the theory and show its degree of conservatism and scope of applicability., Comment: Original first draft. Successive version submitted to scientific journal

Published
2023

16. Removing Chaos while preserving equilibria by means of 2-contraction

Author

Angeli, David, Martini, Davide, Innocenti, Giacomo, and Tesi, Alberto

Abstract

Conditions for designing a feedback control law to remove the dense set of Unstable Periodic Orbits and chaotic attractors while preserving equilibria are formulated in terms of 2-contractivity of the closed loop system, by means of the second additive compound of the system's Jacobian. Matrix inequalities to allow computing the control gain matrix are discussed. An example of application of the method to the Thomas’ system is presented.

Published
2024
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17. Chua’s Circuit With Tunable Nonlinearity Based on a Nonvolatile Memristor: Design and Realization

Author

Escudero, Manuel, Spiga, Sabina, Marco, Mauro Di, Forti, Mauro, Innocenti, Giacomo, Tesi, Alberto, Corinto, Fernando, and Brivio, Stefano

Abstract

Nonvolatile memristive devices display nonlinear characteristics suitable for implementing circuits exhibiting oscillations or more complex dynamic behaviors, including chaos. However, the results presented in related works are mostly limited to simulations and employing ideal memristor models whose resistance is governed by a charge-flux relation that is not connected to real devices, thus hindering the realization of such nonlinear oscillators. In this work, we present the framework for the physical implementation of a tunable memristor Chua’s circuit, which is based on a nonvolatile memristive device that provides the nonlinear conductance required by the circuit and the possibility to tune it for the purpose of selecting among different oscillation patterns. We first establish design guidelines to guarantee complex oscillations in the tunable memristor Chua’s circuit. Further, we physically implement the circuit after characterizing and modeling the tunable current-voltage characteristic of a real device. Our circuit successfully generates different oscillation patterns just by programming the nonvolatile memristive device to different states. The devised design guidelines and device modeling were used to extend the experimental work and draw further requirements for device properties for a successful circuit implementation.

Published
2024
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22. Complete Stability of Neural Networks With Extended Memristors

Author

Marco, Mauro Di, Forti, Mauro, Moretti, Riccardo, Pancioni, Luca, and Tesi, Alberto

Subjects
Complete stability (CS), Lyapunov method, Complete stability (CS), differential variational inequalities, in-memory computing, linear matrix inequality (LMI), Lyapunov diagonally stable (LDS) matrices, Lyapunov method, memristor, neural networks (NNs), differential variational inequalities, in-memory computing, neural networks (NNs), Lyapunov diagonally stable (LDS) matrices, linear matrix inequality (LMI), memristor
Published
2023

27. Positive Forms

Author

Chesi, Graziano, Garulli, Andrea, Tesi, Alberto, Vicino, Antonio, Morari, Manfred, editor, Thoma, Manfred, editor, Chesi, Graziano, Garulli, Andrea, Tesi, Alberto, and Vicino, Antonio

Published
2009
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28. Positivity Gap

Author

Chesi, Graziano, Garulli, Andrea, Tesi, Alberto, Vicino, Antonio, Morari, Manfred, editor, Thoma, Manfred, editor, Chesi, Graziano, Garulli, Andrea, Tesi, Alberto, and Vicino, Antonio

Published
2009
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48. A convex lower bound for the real [l.sub.2] parametric stability margin of linear control systems with restricted complexity controllers

Author

Bianchini, Gianni, Falugi, Paola, Tesi, Alberto, and Vicino, Antonio

Subjects
Robust statistics -- Usage, Perturbation (Mathematics) -- Analysis, Convex domains -- Analysis
Abstract

In this note the problem of restricted complexity stability margin maximization (RCSMM) for single-input--single-output (SISO) plants affected by rank one real perturbations is considered. This problem amounts to maximizing the real [l.sub.2] parametric stability margin over an assigned class of restricted complexity controllers, which are described by rational transfer functions of fixed order with coefficients depending affinely on some free parameters. It is shown that the RCSMM problem, which is nonconvex in general, can be approached by means of convex optimization methods. Specifically, a lower bound of the stability margin, whose maximization can be accomplished via linear matrix inequality (LMI) techniques, is developed. Index Terms--Convex optimization, parametric stability margin, restricted complexity controllers, robust control.

Published
2007

50. Global [H.sub.[infinity]] controllers for a class of nonlinear systems

Author

Bianchini, Gianni, Genesio, Roberto, Parenti, Alessandro, and Tesi, Alberto

Abstract

In this note, the problem of state feedback [H.sub.[infinity]] control for a class of nonlinear systems is considered. The class under study is a generalization of the well-known Lur'e systems. The [H.sub.[infinity]] problem is addressed via a class of storage functions of the Lur'e-Postnikov type whose integral term is parameterized by a nonlinear scalar function. The related [H.sub.[infinity]] controllers consist of a linear term, which is designed for the underlying linearized system, plus a nonlinear term which depends on the nonlinear function. A simple geometrical criterion is provided for the characterization of the set of controllers which ensure a given level of [L.sub.2]-performance globally. Some guidelines for an effective design of the controller within this set are discussed via two examples. Index Terms--Control and optimization, nonlinear [H.sub.[infinity]] control, nonlinear systems, optimal control, robust control.

Published
2004

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