Search results for "chaos"

Analyse de la dynamique de la durée du potentiel d'action cardiaque à travers un modèle itératif

2013

International audience; Le présent travail a pour but de caractériser, par une étude mathématique rigoureuse la dynamique du modèle itératif de la durée du potentiel d'action. L'étude de ce modèle, qui découle de celui de Beeler Reuter (BR), se caractérise par une dynamique matérialisée par une courbe de restitution et qui peut servir d'outil pertinent dans l'analyse et le diagnostic d'arythmie. Par ailleurs l'analyse de la stabilité du modèle permet de définir les zones d'existence de différents rythmes cardiaques.

Predictive Chaos Control for the 1D-map of Action Potential Duration

2016

International audience; In the present work, a nonlinear control method namely predictive controlis investigated. The proposed method allows stabilizing unstable period-1 rhythm.Using mathematical analysis and computer simulations, we show that this methodcan be used to control chaotic behavior or pathological rhythms. As example, theresults are illustrated in the case of the 1D-map action potential duration (APDi+1)which modelizes the cardiac action potential duration as the function of the previousone (APDi).

Robustly correlated key‐medical image for DNA‐chaos based encryption

2021

Abstract Medical images include confidential and sensitive information about patients. Hence, ensuring the security of these images is a crucial requirement. This paper proposes an efficient and secure medical image encryption‐decryption scheme based on deoxyribonucleic acid (DNA), one‐dimensional chaotic maps (tent and logistic maps), and hash functions (SHA‐256 and MD5). The first part of the proposed scheme is the key generation based on the hash functions of the image and its metadata. The key then is highly related and intensely sensitive to the original image. The second part is the rotation and permutation of the first two MSB bit‐plans of the medical image to reduce its black backgr…

Origin and extinction of chaotic oscillations in the Belousov-Zhabotinsky reaction

2010

Chaos dans les ventes de biens à la mode et implication pour le contrôle de gestion

2011

Objective - This article aims at showing that management control should drop cybernetic control for some activities of good sales. Study design - Reviewing Sutherland's (1975) and Hofstede's (1978) articles, it seems that activities of good sales can be controlled by a cybernetic control, like program-planning-budgeting systems. If sales of fashion goods were linear, like Miller et al.'s (1993) model, their forecasting would be possible and useful. However, two other models show that these sales could be chaotic (Granovetter and Soong ; Nakayama and Nakamura, 2004). In these models, the sales of fashion goods could be unpredictable beyond short intervals. The presence of chaotic patterns in…

Nonlinear dynamics and chaos in classical Coulomb-interacting many-body billiards

2013

Chaos and nonlinear dynamics of single-particle Hamiltonian systems have been extensively studied in the past; however, less is known about interacting many-body systems in this respect even though all physical systems include particle-particle interactions in one way or another. To study Hamiltonian chaos, two-dimensional billiards are usually employed, and due to the realization of billiards in semiconductor quantum dots, the electrostatic Coulomb interaction is the natural choice for the interparticle interaction. Yet, surprisingly little is known about chaos and nonlinear dynamics of Coulomb-interacting many-body billiards. To address the challenging problems of interacting many-body bi…

Assessing Non-Linear Structures in Real Exchange Rates Using Recurrence Plot Strategies

2002

MODELLING AND SIMULATING RISKS IN THE TRAINING OF THE HUMAN RESOURCES BY APPLYING THE CHAOS THEORY

2012

The article approaches the modelling and simulation of risks in the training of the human resources, as well as the forecast of the degree of human resources training impacted by risks by applying the mathematical tools offered by the Chaos Theory and mathematical statistics. We will highlight that the level of knowledge, skills and abilities of the human resources from an organization are autocorrelated in time and they depend on the level of a previous moment of the training, as well as on the impact of the risk factors that can materialize in the process of the continuous training of human resources. The process of self-correlation and continuous training ensures the sustainable and qual…

Chaos and its Degradation-Promoting-Based Control in an Antithetic Integral Feedback Circuit

2022

This letter deals with a novel variant of antithetic integral feedback controller (AIFC) motifs which can feature robust perfect adaptation, a pervasive (desired) ability in natural (synthetic) biomolecular circuits, when coupled with a wide class of process networks to be regulated. Using the separation of timescales in the proposed kind of AIFC, here we find a reducedorder controller that captures the governing slow part of the original solutions under suitable assumptions. Inspired by R(ossler systems, we then make use of such a simpler controller to show that the antithetic circuit can exhibit chaotic behaviors with strange attractors, where the bifurcation from a homeostatic state to c…

Time-delay control for stabilization of the Shapovalov mid-size firm model

2020

Control and stabilization of irregular and unstable behavior of dynamic systems (including chaotic processes) are interdisciplinary problems of interest to a variety of scientific fields and applications. Using the control methods allows improvements in forecasting the dynamics of unstable economic processes and offers opportunities for governments, central banks, and other policy makers to modify the behaviour of the economic system to achieve its best performance. One effective method for control of chaos and computation of unstable periodic orbits (UPOs) is the unstable delay feedback control (UDFC) approach, suggested by K. Pyragas. This paper proposes the application of the Pyragas' me…