An Invariance Principle for Discontinuous Dynamic Systems With Application to a Coulomb Friction Oscillator

2000 ◽  
Vol 122 (4) ◽  
pp. 687-690 ◽  
Author(s):  
Joaquin Alvarez ◽  
Iouri Orlov ◽  
Leonardo Acho

An invariance principle for a class of ordinary differential equations with discontinuous right-hand side is developed. Based on this principle, asymptotic stability of one-degree-of-freedom mechanical oscillators with Coulomb friction is studied. The system is shown to be asymptotically stabilizable via a static feedback of the position, unlike those systems with no friction, whose stabilization requires a dynamic feedback when the position is the only available measurement. Along with this development, a velocity observer is proposed. Theoretical results of the paper are supported by some numerical simulations which, in addition, carry out a finite-time convergence of the controller and the observer proposed. [S0022-0434(00)00804-2]

Author(s):  
Rachida Mezhoud ◽  
Khaled Saoudi ◽  
Abderrahmane Zaraï ◽  
Salem Abdelmalek

AbstractFractional calculus has been shown to improve the dynamics of differential system models and provide a better understanding of their dynamics. This paper considers the time–fractional version of the Degn–Harrison reaction–diffusion model. Sufficient conditions are established for the local and global asymptotic stability of the model by means of invariant rectangles, the fundamental stability theory of fractional systems, the linearization method, and the direct Lyapunov method. Numerical simulation results are used to illustrate the theoretical results.


2018 ◽  
Vol 12 (2) ◽  
pp. 171
Author(s):  
Enobong E. Joshua ◽  
Cec Ekemini T. Akpan

This paper investigates the global asymptotic stability of a Delayed Extended Rosenzweig-MacArthur Model via Lyapunov-Krasovskii functionals. Frequency sweeping technique ensures stability switches as the delay parameter increases and passes the critical bifurcating threshold.The model exhibits a local Hopf-bifurcation from asymptotically stable oscillatory behaviors to unstable strange chaotic behaviors dependent of the delay parameter values.Hyper-chaotic fluctuations were observed for large delay values far away from the critical delay margin. Numerical simulations of experimental data obtained via non-dimensionalization have shown the applications of theoretical results in ecological population dynamics.


2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Hai Zhang ◽  
Daiyong Wu ◽  
Jinde Cao

We discuss the delay-independent asymptotic stability of Caputo type fractional-order neutral differential systems with multiple discrete delays. Based on the algebraic approach and matrix theory, the sufficient conditions are derived to ensure the asymptotic stability for all time-delay parameters. By applying the stability criteria, one can avoid solving the roots of transcendental equations. The results obtained are computationally flexible and convenient. Moreover, an example is provided to illustrate the effectiveness and applicability of the proposed theoretical results.


2019 ◽  
Vol 97 (Supplement_2) ◽  
pp. 237-237
Author(s):  
Maria Haag ◽  
Justin Le Tourneau ◽  
Rose Marra ◽  
William Lamberson

Abstract Understanding the systematic effects of genetic change is critical for any livestock producer. To help students learn about such changes we developed a beef cattle breeding simulation. This simulation features dynamic feedback designed to assist students in understanding their progress. Without feedback, students are often unable to make sense of their results which can inhibit their learning. The literature on feedback in simulations has shown varying effectiveness complexity levels, timing, and personalization. Oftentimes, this variation is associated with learner characteristics such as prior knowledge or gender. In our previous work, we determined that students did not always read feedback which reduces the likelihood of misconception reversal. Therefore, the aim of our current work was to identify feedback designs that ensure students are engaging with the material. To do this we designed two types of feedback: Static and Interactive. In Static feedback, students were simply shown the feedback and could click through—like the previous version. In Interactive feedback, students were required to answer a question regarding the feedback. We then assigned 242 students from 10 universities to one feedback type at random. We found that students in low and moderate performance groups using Interactive feedback showed higher (P = 0.06) posttest scores than those using Static feedback. No difference was observed in high performers which was expected according to the literature. This study demonstrated that feedback effectiveness is dependent on learner characteristics such as performance level. Thereby, developing feedback that is tailored to the student delivers a more personalized learning experience which can improve learning.


Author(s):  
Najah F. Jasim

This paper addresses sufficient conditions for asymptotic stability of classes of nonlinear switched systems with external disturbances and arbitrarily fast switching signals. It is shown that asymptotic stability of such systems can be guaranteed if each subsystem satisfies certain variants of observability or 0-distinguishability properties. In view of this result, further extensions of LaSalle stability theorem to nonlinear switched systems with arbitrary switching can be obtained based on these properties. Moreover, the main theorems of this paper provide useful tools for achieving asymptotic stability of dynamic systems undergoing Zeno switching.


Author(s):  
Mohsen Jafari ◽  
Hossein Kheiri ◽  
Azizeh Jabbari

In this paper, we consider a tuberculosis model with incomplete treatment and extend the model to a Caputo fractional-order and two-patch version with exogenous re-infection among the treated individuals, in which only susceptible individuals can travel freely between the patches. The model has multiple equilibria. We determine conditions that lead to the appearance of a backward bifurcation. The results show that the TB model can have exogenous reinfection among the treated individuals and, at the same time, does not exhibit backward bifurcation. Also, conditions that lead to the global asymptotic stability of the disease-free equilibrium are obtained. In case without reinfection, the model has four equilibria. In this case, the global asymptotic stability of the equilibria is established using the Lyapunov function theory together with the LaSalle invariance principle for fractional differential equations (FDEs). Numerical simulations confirm the validity of the theoretical results.


2019 ◽  
Vol 38 (6) ◽  
pp. 159-171 ◽  
Author(s):  
Vahid Mohammadnezhad ◽  
Mostafa Eslami ◽  
Hadi Rezazadeh

In this paper, we first study stability analysis of linear conformable fractional differential equations system with time delays. Some sufficient conditions on the asymptotic stability for these systems are proposed by using properties of the fractional Laplace transform and fractional version of final value theorem. Then, we employ conformable Euler’s method to solve conformable fractional differential equations system with time delays to illustrate the effectiveness of our theoretical results


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