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Stability analysis

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Articles 1 - 11 of 11

Full-Text Articles in Controls and Control Theory

Stability Analysis Of Thermohaline Convection With A Time-Varying Shear Flow Using The Lyapunov Method, Kalin Kochnev Dec 2025

Stability Analysis Of Thermohaline Convection With A Time-Varying Shear Flow Using The Lyapunov Method, Kalin Kochnev

Honors Scholar Theses

This work applies the Lyapunov method to identify instabilities and compute the growth rate of a linear time-varying system. The linear system studied describes cold fresh water on top of hot salty water with a periodically time-varying background shear flow. A time-dependent weighting matrix is employed to construct a Lyapunov function candidate. The resulting linear matrix inequalities are discretized in time using the forward Euler method. As the number of temporal discretization points increases, the growth rate predicted by the Lyapunov method or Floquet theory, used for comparison, will converge to the same value obtained from numerical simulations. Furthermore, the …


Heuristic Strategies For Process Stabilization Using Proportional Control Implemented By A Noisy Quantum Simulator, Keshav Kasturi Rangan, Helen Durand Aug 2025

Heuristic Strategies For Process Stabilization Using Proportional Control Implemented By A Noisy Quantum Simulator, Keshav Kasturi Rangan, Helen Durand

Chemical Engineering and Materials Science Faculty Research Publications

Processing and storage demands of industrial processes are causing fields such as optimization, scheduling, and control to assess the effectiveness of quantum devices in their applications. A key objective of control systems is to ensure process safety. This paper focuses on the potential of quantum devices to compute control inputs that maintain system safety despite sources of nondeterminism inherent to currently available quantum devices (quantum noise). In our previous work, we employed a quantum simulator to assess whether a quantum implementation of a proportional (P) control law could stabilize a single-input/single-output system under quantum noise approximated from a real quantum …


Stability Approximation Method For Pulse Loads In Power Electronic Systems, Eduardo A. Marmol D Jan 2022

Stability Approximation Method For Pulse Loads In Power Electronic Systems, Eduardo A. Marmol D

Dissertations, Master's Theses and Master's Reports

Pulse loads on power electronic distribution systems are becoming very popular nowadays as the components of ships and airplanes are moving to more electric power. However, the pulse loads have a destabilizing effect on the power distribution system. Usually, the method used to study the stability of this type of system are small-signal analyses and are based on a system where the load is modeled as a constant. Since DC-DC systems with pulsed loads are very nonlinear, a small-signal analysis does not provide helpful information related to the stability of the system. The work presented in this thesis focuses on …


Enhancing Practical Tractability Of Lyapunov-Based Economic Model Predictive Control, Helen Durand, Dominic Messina Jul 2020

Enhancing Practical Tractability Of Lyapunov-Based Economic Model Predictive Control, Helen Durand, Dominic Messina

Chemical Engineering and Materials Science Faculty Research Publications

Lyapunov-based economic model predictive control (LEMPC) is an optimization-based control design that computes economically-optimal control actions for a process while maintaining the closed-loop state within a bounded region of state-space; however, it may be difficult to design in practice without closed-loop simulations, as it requires an auxiliary stabilizing controller, Lyapunov function, and a number of sets to be developed to ensure closed-loop stability. Practical application of this method could benefit from methods which make it more likely that, without simulations to identify aspects of the control design that would provide stability, controller parameters can be selected that would maintain stability. …


Mitigating Cyberattack Impacts Using Lyapunov-Based Economic Model Predictive Control, Helen Durand, Matthew Wegener Jul 2020

Mitigating Cyberattack Impacts Using Lyapunov-Based Economic Model Predictive Control, Helen Durand, Matthew Wegener

Chemical Engineering and Materials Science Faculty Research Publications

One of the pressing concerns for next-generation manufacturing is the development of techniques for guaranteeing that a control system is cyberattack-resilient in the sense that even if a cyberattack is successful at breaking information technology-based defenses (e.g., it succeeds at providing a false sensor measurement to the controller), closed-loop stability is still maintained. Our prior work has provided a nonlinear systems definition for cyberattacks. This work explores how a nonlinear systems perspective on cyberattack-resilience for false sensor measurements provided to controllers may allow an economic model predictive control (EMPC) formulation known as Lyapunov-based EMPC (LEMPC) to be designed such that …


Lyapunov-Based Economic Model Predictive Control With Taylor Series State Approximations, Keshav Kasturi Rangan, Helen Durand Jul 2020

Lyapunov-Based Economic Model Predictive Control With Taylor Series State Approximations, Keshav Kasturi Rangan, Helen Durand

Chemical Engineering and Materials Science Faculty Research Publications

A method for integrating optimization and control during on-line process operation is known as economic model predictive control (EMPC). EMPC optimizes a general cost function which reflects process economics subject to a model of the process. One formulation of EMPC which can maintain closed-loop stability in the presence of sufficiently small disturbances is Lyapunov-based EMPC (LEMPC). In this work, we make precise connections between closed-loop stability considerations under LEMPC and numerical approximations (via Taylor series) of the solution of the nonlinear dynamic model of the process used in the controller. A chemical process example is utilized to demonstrate the concepts …


Some Insights Into The Migration Of Double Imaginary Roots Under Small Deviation Of Two Parameters, Dina Alina Irofti, Keqin Gu, Islam Boussaada, Silviu-Iulian Niculescu Feb 2018

Some Insights Into The Migration Of Double Imaginary Roots Under Small Deviation Of Two Parameters, Dina Alina Irofti, Keqin Gu, Islam Boussaada, Silviu-Iulian Niculescu

SIUE Faculty Research, Scholarship, and Creative Activity

This paper studies the migration of double imaginary roots of the systems’ characteristic equation when two parameters are subjected to small deviations. The proposed approach covers a wide range of models. Under the least degeneracy assumptions, we found that the local stability crossing curve has a cusp at the point that corresponds to the double root, and it divides the neighborhood of this point into an S-sector and a G-sector. When the parameters move into the G-sector, one of the roots moves to the right halfplane, and the other moves to the left half-plane. When the parameters move into the …


Stability Analysis And Control Synthesis Of Affine Fuzzy Systems, Ruiyao Gao, Aidan O'Dwyer Jan 2007

Stability Analysis And Control Synthesis Of Affine Fuzzy Systems, Ruiyao Gao, Aidan O'Dwyer

Conference papers

This paper presents an approach to stability analysis and control synthesis of affine fuzzy systems. The analysis is based on quadratic Lyapunov functions. The approach considers the nonlinear offset terms in affine fuzzy systems as non-vanishing perturbations added to the corresponding nominal linear blending systems. The affine fuzzy system is bounded by an ultimate limit if the corresponding linear blending system is exponentially stable. A state feedback controller with an extra term is designed with guaranteed global stability. The ultimate bounds are determined for both the open loop system and the compensated system.


Smith Predictor Structure Stability Analysis Using Mikhailov Stability Criterion, Pauline Sourdille, Aidan O'Dwyer, Eugene Dermot Coyle Professor Jan 2005

Smith Predictor Structure Stability Analysis Using Mikhailov Stability Criterion, Pauline Sourdille, Aidan O'Dwyer, Eugene Dermot Coyle Professor

Conference papers

As is well known, stability is an important requirement for control systems. Due to the nature of time-delay processes, common methods to evaluate stability may be difficult to use. In 1938, Mikhailov proved a frequency response criterion, which is sufficient and necessary for the stability of processes described by known n-th order constant coefficient linear differential equations. This paper presents the Mikhailov method and the application of this method to a Smith predictor structure controlled by a PI controller.


On Stability Of Affine Blending Systems, Ruiyao Gao, Aidan O'Dwyer, Seamus Mcloone, Eugene Dermot Coyle Professor Jan 2003

On Stability Of Affine Blending Systems, Ruiyao Gao, Aidan O'Dwyer, Seamus Mcloone, Eugene Dermot Coyle Professor

Conference papers

This paper presents a novel approach to stability analysis of affine blending systems. The analysis is based on Quadratic Lyapunov functions. The approach considers the nonlinear offset term in affine blending systems as non-vanishing perturbations added to the corresponding nominal linear blending systems. The affine blending systems will be bounded if the corresponding linear blending system is exponentially stable. The bound is determined by an ultimate limit, which is proportional to the maximum of the offset terms of each affine system.


Modeling Electromagnetic Disturbances In Closed-Loop Computer Controlled Flight Systems, W. Steven Gray, Oscar R. Gonzalez Jan 1998

Modeling Electromagnetic Disturbances In Closed-Loop Computer Controlled Flight Systems, W. Steven Gray, Oscar R. Gonzalez

Electrical & Computer Engineering Faculty Publications

High intensity electromagnetic radiation has been demonstrated to be a source of computer upsets in commercially available digital flight control systems. In this paper we introduce an electromagnetic disturbance model which can be used for stability analysis and augmentation of any such digitally implemented control law. The model is composed of a Markovian exosystem supplying radiation events to a discrete-time jump linear system which models how the radiation interferes with the nominal operation of the closed-loop system. We discuss how this model can be used to characterize stability and how it can be parametrized and validated in an experimental setting.