Continuous Uniform Finite Time Stabilization of Planar Controllable Systems

Continuous homogeneous controllers are utilized in a full state feedback setting for the uniform finite time stabilization of a perturbed double integrator in the presence of uniformly decaying piecewise continuous disturbances. Semiglobal strong $\mathcal{C}^1$ Lyapunov functions are identified to establish uniform asymptotic stability of the closed-loop planar system. Uniform finite time stability is then proved by extending the homogeneity principle of discontinuous systems to the continuous case with uniformly decaying piecewise continuous nonhomogeneous disturbances. A finite upper bound on the settling time is also computed. The results extend the existing literature on homogeneity and finite time stability by both presenting uniform finite time stabilization and dealing with a broader class of nonhomogeneous disturbances for planar controllable systems while also proposing a new class of homogeneous continuous controllers

Interval stability for complex systems

Stability of dynamical systems against strong perturbations is an important problem of nonlinear dynamics relevant to many applications in various areas. Here, we develop a novel concept of interval stability, referring to the behavior of the perturbed system during a finite time interval. Based on this concept, we suggest new measures of stability, namely interval basin stability (IBS) and interval stability threshold (IST). IBS characterizes the likelihood that the perturbed system returns to the stable regime (attractor) in a given time. IST provides the minimal magnitude of the perturbation capable to disrupt the stable regime for a given interval of time. The suggested measures provide important information about the system susceptibility to external perturbations which may be useful for practical applications. Moreover, from a theoretical viewpoint the interval stability measures are shown to bridge the gap between linear and asymptotic stability. We also suggest numerical algorithms for quantification of the interval stability characteristics and demonstrate their potential for several dynamical systems of various nature, such as power grids and neural networks

Finite Frequency H

This paper investigates the problem of finite frequency (FF) H∞ filtering for time-delayed singularly perturbed systems. Our attention is focused on designing filters guaranteeing asymptotic stability and FF H∞ disturbance attenuation level of the filtering error system. By the generalized Kalman-Yakubovich-Popov (KYP) lemma, the existence conditions of FF H∞ filters are obtained in terms of solving an optimization problem, which is delay-independent. The main contribution of this paper is that systematic methods are proposed for designing H∞ filters for delayed singularly perturbed systems

Non-Lyapunov stability of the fractional-order time-varying delay systems

U ovom radu, kriterijumi stabilnosti na konačnom vremenskom intervalu su prošireni na nelinearne nehomogene perturbovane sisteme necelobrojnog reda koji sadrže višestruka vremenski promenljiva kašnjenja. Dobijeni su dovoljni uslovi stabilnosti za sisteme necelog reda sa višestrukim vremenskim kašnjenjima korišćenjem generalizovanog i klasičnog Gronwallovog pristupa. Numerički primer je dat u cilju ilustracije značaja dobijenog rezultata.In this paper, the finite-time stability criteria are extended to nonlinear nonhomogeneous perturbed fractional-order systems including multiple time-varying delays. The sufficient conditions of a stability for the fractional systems with multiple time delays are obtained by using the generalized and classical Gronwall's approach. A numerical example is presented to illustrate the validity of the obtained result

Non-Lyapunov stability of the fractional-order time-varying delay systems

U ovom radu, kriterijumi stabilnosti na konačnom vremenskom intervalu su prošireni na nelinearne nehomogene perturbovane sisteme necelobrojnog reda koji sadrže višestruka vremenski promenljiva kašnjenja. Dobijeni su dovoljni uslovi stabilnosti za sisteme necelog reda sa višestrukim vremenskim kašnjenjima korišćenjem generalizovanog i klasičnog Gronwallovog pristupa. Numerički primer je dat u cilju ilustracije značaja dobijenog rezultata.In this paper, the finite-time stability criteria are extended to nonlinear nonhomogeneous perturbed fractional-order systems including multiple time-varying delays. The sufficient conditions of a stability for the fractional systems with multiple time delays are obtained by using the generalized and classical Gronwall's approach. A numerical example is presented to illustrate the validity of the obtained result

Finite-time stability analysis of fractional order time delay systems: Bellman-Gronwall's approach

Ovaj rad proširuje neke osnovne rezultate iz oblasti praktične stabilnosti i stabilnosti na konačnom vremenskom intervalu na nelinearne, perturbovane sisteme sa kašnjenjem necelobrojnog reda gde je predložen postupak testiranja robusne stabilnosti. Proučavan je problem dovoljnih uslova koji omogućavaju da trajektorije sistema ostaju unutar a priori zadatih skupova i to za posebnu klasu nelinearnih sistema sa kašnjenjem necelobrojnog reda.The paper extends some basic results from the area of finite time and practical stability to nonlinear, perturbed, fractional order time-delay systems where a robust stability test procedure is proposed. The problem of sufficient conditions that enable system trajectories to stay within the a priori given sets for the particular class of nonlinear fractional order time delay systems is examined

Finite-time stability analysis of fractional order time delay systems: Bellman-Gronwall's approach

Ovaj rad proširuje neke osnovne rezultate iz oblasti praktične stabilnosti i stabilnosti na konačnom vremenskom intervalu na nelinearne, perturbovane sisteme sa kašnjenjem necelobrojnog reda gde je predložen postupak testiranja robusne stabilnosti. Proučavan je problem dovoljnih uslova koji omogućavaju da trajektorije sistema ostaju unutar a priori zadatih skupova i to za posebnu klasu nelinearnih sistema sa kašnjenjem necelobrojnog reda.The paper extends some basic results from the area of finite time and practical stability to nonlinear, perturbed, fractional order time-delay systems where a robust stability test procedure is proposed. The problem of sufficient conditions that enable system trajectories to stay within the a priori given sets for the particular class of nonlinear fractional order time delay systems is examined

Limitations of Passive Protection of Quantum Information

The ability to protect quantum information from the effect of noise is one of the major goals of quantum information processing. In this article, we study limitations on the asymptotic stability of quantum information stored in passive N-qubit systems. We consider the effect of small imperfections in the implementation of the protecting Hamiltonian in the form of perturbations or weak coupling to a ground state environment. We prove that, regardless of the protecting Hamiltonian, there exists a perturbed evolution that necessitates a final error correcting step when the state of the memory is read. Such an error correction step is shown to require a finite error threshold, the lack thereof being exemplified by the 3D compass model. We go on to present explicit weak Hamiltonian perturbations which destroy the logical information stored in the 2D toric code in a time O(log(N)).Comment: 17 pages and appendice