INTERNATIONAL JOURNAL of CHAOS THEORY and APPLICATIONS Vol. 5, Issue # 1, 2000
Invited paperSystem reconstruction in presence of dynamical noise
Libero Battiston° and Maurice Rossi*
°ISDGM- CNR, S. Polo 1364 Venezia, 30125 Italia
*Laboratoire de Modelisation en Mecanique, Universite de Paris VI,
4 Place Jussieu, F-75252 Paris FranceAbstract
The reconstruction of a dynamical system in presence of dynamical noise is addressed. The analytical form of the flow is assumed to belong to a given set of dynamical systems parametrized by several coefficients. The noise is white and of such amplitude that usual backpropagation or local linear approximations fail to identify the dynamics. A statistical approach based on the theory of stochastic equations is proposed. Its application to a noisy Lorenz dynamical system shows its practical usefulness: time series should be long enough but within the reach of real experiments.Keywords: dynamical systems, noise, stochastic equations, Fokker-Planck equation, time series analysis and reconstruction
Invited paperFuzzy inference systems (FIS) for classification and identification
of plasma columns in Tokamak reactors
Mario Versaci and Francesco Carlo Morabito
Associazione EURATOM/ENEA/CREATE
Università di Reggio Calabria ? Facoltà di Ingegneria ? DIMET
Via Graziella, Loc. Feo di Vito ? I ? 89100 Reggio Calabria, Italy
versaci@ing.unirc.it, morabito@unirc.itAbstract
This paper is mainly concerned with the application of a novel technique of data interpretation to the identification of plasma columns in Tokamak reactors for nuclear fusion applications. The proposed method exploits several concepts derived from fuzzy system theory and particularly the idea of fuzzy inference. Additionally, a qualitative reasoning technique for easily classifying the type of plasma equilibrium by direct inspection of the data measurement reading has been developed. The proposed technique is used to analyze simulated databases of elongated multi?category plasma equilibria based on the ASDEX?Upgrade geometry and poloidal field coils configuration. As well as demonstrating the successful recovery of scalar equilibrium parameters, we show that the fuzzy inference technique can yield practical advantages compared with earlier methods, also exploiting neural systems. An original technique of identification based on the extraction of a set of fuzzy rules directly from the available database has been proposed for the ASDEX?Upgrade configuration; however, the proposed methodologies can be applied to any kind of configuration. To improve the identification capabilities of the developed basic fuzzy inference model, an adaptive fuzzy?neural inference system based on adaptive network schemes is proposed, Finally, a technique for sensor selection and ranking based on fuzzy logic aiming to carry out dimensionality reduction is presented.Keywords: Tokamaks, fuzzy inference systems, classification and identification problems
Invited paperA new method to cool charged particles in a Paul trap
Guang-Cai Zhang, Jing-Ling Shen, Jian-Hua Dai, Hong-Jun Zhang
Laboratory of Optical Physics, Institute of Physics,
Chinese Academy of Sciences, Beijing 100080, P. R. ChinaAbstract
A new method to cool particles in a Paul trap without a laser is presented and simulated numerically. By adjusting the electric potential applied to electrodes as the feedback, an effect similar to that of laser cooling can be achieved. Results show that feedback control, with or without delay, continuously or discretely, and with or without noise, can effectively reduce kinetic energy and lead the system to a low periodic orbit over a wide range of control intensity. The final orbit of the controlled system is near to an elliptic orbit of the uncontrolled system and the system maintains regular motion when control is withdrawn.Keywords: Paul trap, trapped ions, particles in electromagnetic fields, cooling ions, control chaos
Attractor control of the stability of lysozymesRegular paper
Adriana Isvoran*, Daniela Dolha*, V. V. Morariu***
*University of the West Timisoara, Department of Physics
Bv. Parvan no. 4, 1900-Timisoara, Romania, E-mail: adii@galileo.uvt.ro
** National Institute for Research and Development of Isotopic and Molecular Technology
P.O. Box 700, 3400-Cluj Napoca 5, RomaniaAbstract
The characteristics of attractor control of the stability of three different species of lysozymes have been detected. The dimensions of the attractors for the free and complexed enzymes are: 2.4±0.07 for the free human lysozyme and 1.98±0.13 for its complex with tetra-acetyl-chitotetraose, 2.55±0.16 for the free egg white lysozyme and 2.57±0.16 for its complex with 2 N-tetra-acetyl-chitotriose, 3.14±0.15 for the free bacteriophage T4 lysozyme and 3.4±0.1 for its complex with N-butylbenzen. The differences between the dimensions of the attractors of the three lysozymes have not statistical significance and we conclude that the process of evolution did not affect the spatial properties and the stability of lysozymes. All the consequences of the presence of the attractors are fulfilled: the autocorrelation functions show strong damping, the Poincaré plots present preferentially occupied regions and the first Lyapunov coefficients are positive.Keywords: lysozyme, biological evolution, attractor, autocorrelation function, Poincaré plot, Lyapunov coefficient
Patent SurveyRecent patents on chaos applications
Horia-Nicolai Teodorescu
Romanian Academy, Section for Information Sciences,
Calea Victoriei 125, Bucharest, RomaniaAbstract
Recently applied for or issued patents in the field of nonlinear dynamic systems are listed and several of them briefly presented and discussed. Conclusions on the state of the art in the field are derived.
Letter to EditorCorrection concerning the article "The attractors of some contractive dynamical systems"
Dana Constantinescu
University of Craiva, Dept. Mathematics, Craiva, RomaniaAbstract not available.
Bulletin SectionAbstracts not available.
Back to the TOC/Abstracts list page
© Technique & Technologies Press Ltd.