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Numerical investigation of bubble nonlinear dynamics characteristics

AIP conference Proceedings 2015年第1期1685卷

作者： Jie Shi Desen Yang Haoyang Zhang Shengguo Shi Wei Jiang Bo Hu Acoustic Science and Technology Laboratory Harbin Engineering University Harbin 150001 China College of Underwater Acoustic Engineering Harbin Engineering University Harbin 150001 China

The complicated dynamical behaviors of bubble oscillation driven by acoustic wave can provide favorable conditions for many engineering applications. On the basis of Keller-Miksis model, the influences of control parameters, including acoustic frequency, acoustic pressure and radius of gas bubble, are discussed by utilizing various numerical analysis methods, Furthermore, the law of power spectral variation is studied. It is shown that the complicated dynamic behaviors of bubble oscillation driven by acoustic wave, such as bifurcation and chaos, further the stimulated scattering processes are revealed.

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Method of the calculation of spectrum of Lyapunov exponents for the analysis of dynamics of beam-plasma systems

Method of the calculation of spectrum of Lyapunov exponents ...

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IEEE International conference on Plasma Science (ICOPS)

作者： Semen A. Kurkin Nikita S. Frolov Vladimir A. Maximenko Alexander E. Hramov Alexey A. Koronovskii Saratov State Technical University Saratov Russia Saratov State University Saratov Russia

Summary form only given. nonlinear dynamics and chaos in plasma devices and microwave systems with interacting electron and electromagnetic waves are often observed in bounded plasmas and electron and ions beams, where the nonlinearity and plasma instabilities are combined with dissipation caused by current flow to the boundary electrodes. Therefore, the development of the methods of analysis of nonlinear dynamics in the spatially extended beam-plasma systems is a very important and actual problem due to possible applications of chaos theory in plasma physics, such as the identification of chaotic spatial-temporal oscillations in microwave electronic and plasma devices (e.g., free electron lasers, pasotrons, vircators, etc), chaos control and suppression of turbulence, and chaotic synchronization in the plasma and microwave electronic *** Lyapunov exponents are powerful and useful tool for the complex system dynamics to be analyzed. They are used widely to characterize the systems with small number of degrees of freedom (that is systems with finite phase space) in the different fields of science [1], such as physics, physiology and medicine, molecular dynamics, and astronomy. At the same time, the majority of the plasma systems are characterized by the infinite phase space, since they are the spatially extended active media. Unfortunately, the direct application of the Lyapunov exponent calculation technique (developed for the systems with the small number of degrees of freedom) to the objects of the beam-plasma and electron-wave spatially extended systems is problematic [2]. Recently, the successful attempt to compute the highest Lyapunov exponent taking into account the core features of the spatially extended systems has been made for plasma system models by our scientific group [3]. In the present work, we present the technique of the spectrum of the spatial Lyapunov exponents calculation for the hydrodynamic and particle-in-cell models of distributed bea

关键词： Plasmas chaos Microwave oscillators Physics Masers

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A New Approach to the Study of Heartbeat dynamics Based on Mathematical Model

A New Approach to the Study of Heartbeat Dynamics Based on M...

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21st Iranian conference on Electrical Engineering (ICEE)

作者： Behnia, Sohrab Ziaei, Javid Ghiassi, Marjan Urmia Univ Technol Dept Phys Orumiyeh Iran

ISBN: (纸本)9781467356343

The study of cardiac dynamics by mathematical models has a long history that has been started by using nonlinear oscillators to generate such rhythms. Since cardiac rhythms may exhibit chaotic behaviors, the chaos theory as a powerful tool in studying nonlinear dynamical systems, can be used for analyzing cardiac system. In this paper, based on Grudzinski and Zebrowski's model, the effects of external factors on pacemaker rhythms were studied using a new measure, called the scale index. Obtained results showed that the scale index can detect special behaviors in the action potential whereas the Lyapunov exponent is not capable of uncovering them. Moreover, it was found that the nonperiodicity of pacemaker rhythms in the presence of external periodic force is not high. Finally, it was discovered that the scale index can provide a non-invasive assessment of the heart in real-life conditions.

关键词： Lyapunov methods cardiology chaos mathematical analysis nonlinear dynamical systems oscillators pacemakers

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Introduction of topological horseshoe theory in chaotic research

Introduction of topological horseshoe theory in chaotic rese...

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2nd International conference on Mechanical Properties of Materials and Information Technology, ICMPMIT 2013

作者： Ma, You Jie Song, Shuang Zhou, Xue Song Tianjin University of Technology Tianjin Key Laboratory for Control Theory and Applications in Complicated Systems Nankai District Tianjin 300384 China

ISBN: (纸本)9783037858608

Over the past 10 years, nonlinear dynamics and chaotic theory attracted scholars and people got a deeper understanding of chaos. There are many methods for chaos research, and the method of using topological horseshoe is an important branch of those methods. So far, this is one of the core methods with mathematical rigor for chaos research. Based on simple thinking of geometric space, topological horseshoe build a bridge for numerical and theoretical studies of complex behavior of nonlinear systems so that people can carry out a series of studies for chaotic behavior. This paper introduces the basic content of topological horseshoe theory and the application to a simple power system. © (2013) Trans Tech Publications, Switzerland.

关键词： dynamics

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Nostradamus: Modern methods of Prediction, Modeling and Analysis of nonlinear Systems

Nostradamus: Modern Methods of Prediction, Modeling and Anal...

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conference on Modern methods of Prediction, Modeling and Analysis of nonlinear Systems, Nostradamus 2012

ISBN: (纸本)9783642332265

The proceedings contain 28 papers. The topics discussed include: is hot fusion made feasible by the discovery of cryodynamics?;fitness landscapes and evolutionary dynamics;observer design for polytopic systems: application to chaotic system reconstruction;modeling complexity: from cellular automata to evolutionary game theory and multiagent systems with coalitions;on evolutionary synthesis of chaotic systems;on the evolutionary optimization of chaos control ? a brief survey;the use of soft computing methods for forecasting in business, their applications in practice;adaptive predictive control of time-delay systems;chaos synchronization based on unknown inputs Takagi-Sugeno fuzzy observer;modeling and model predictive control of nonlinear hydraulic system;usage of the evolutionary designed neural network for heat demand forecast;and fuzzy logic decision support for long-term investing in the financial markets.

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Fitness landscapes and evolutionary dynamics

Fitness landscapes and evolutionary dynamics

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conference on Modern methods of Prediction, Modeling and Analysis of nonlinear Systems, Nostradamus 2012

作者： Richter, Hendrik HTWK Leipzig University of Applied Sciences Faculty of Electrical Engineering and Information Technology D-04251 Leipzig Germany

ISBN: (纸本)9783642332265

This key note considers fitness landscapes and their use for understanding evolutionary dynamics in natural and artificial biological systems. Landscape paradigms are meanwhile ubiquitous in several branches of science. This introductory overview discusses concepts, issues and application with a main focus on evolutionary biology and evolutionary computation. © 2013 Springer-Verlag.

关键词： Biology

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Stability Analysis of Digital State Feedback Controlled Boost Converters

Stability Analysis of Digital State Feedback Controlled Boos...

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39th Annual conference of the IEEE Industrial-Electronics-Society (IECON)

作者： Giaouris, Damian Yfoulis, Christos Voutetakis, Spyridon Papadopoulou, Simira

ISBN: (纸本)9781479902248

In this paper we investigate the nonlinear dynamics of DC-DC boost converters under state feedback controllers. We demonstrate that it is possible to have multiple equilibria, which can further bifurcate and result in a torus or even chaos. More specifically, by changing the feedback gains we show that it is possible to have a saddle node and then a period 2 bifurcation. These are then followed by a slow scale bifurcation that results in a 2T torus. Also, the nominal or desired equilibrium hits a border in the state space that forces the steady state duty cycle to become 0. Obviously the occurrence of saturation in the duty cycle or the existence of instabilities can greatly decrease the converter's performance. In this paper we study this behavior: we use semi-analytical methods to locate the stable and unstable period 1 and period 2 orbits, the unstable manifold of the period 1 orbit;and by using the theory of the monodromy matrix enhanced with the saltation matrix we determine the stability of the converter. The latter can be used for design purposes in order to guarantee a stable and satisfactory performance.

关键词： State feedback boost converters bifurcation nonlinear dynamics

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A Genetic Algorithm to Optimize Lazy Learning Parameters for the Prediction of Customer Demands

A Genetic Algorithm to Optimize Lazy Learning Parameters for...

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12th International conference on Machine Learning and Applications (ICMLA)

作者： Kueck, Mirko Scholz-Reiter, Bernd Univ Bremen BIBA Bremer Inst Prod & Logist D-28359 Bremen Germany Univ Bremen D-28359 Bremen Germany

ISBN: (纸本)9780769551449

The prediction of time series is an important task both in academic research and in industrial applications. Firstly, an appropriate prediction method has to be chosen. Subsequently, the parameters of this prediction method have to be adjusted to the time series evolution. In particular, an accurate prediction of future customer demands is often difficult, due to several static and dynamic influences. As a promising prediction method, we propose a lazy learning algorithm based on phase space reconstruction and k-nearest neighbor search. This algorithm originates from chaos theory and nonlinear dynamics. In contrast to widely used linear prediction methods like the Box-Jenkins ARIMA method or exponential smoothing, this method is appropriate to reconstruct additional influences on the time series data and consider these influences within the prediction. However, in order to adjust the parameters of the prediction method to the observed time series evolution, a reasonable optimization algorithm is required. In this paper, we present a genetic algorithm for parameter optimization. In this way, the prediction method is automatically fitted accurately and quickly to observed time series data, in order to predict future values. The performance of the genetic algorithm is evaluated by an application to different time series of customer demands in production networks. The results show that the genetic algorithm is appropriate to find suitable parameter configurations. In addition, the prediction results indicate an improved forecasting accuracy of the proposed prediction algorithm compared to linear standard methods.

关键词： predictive models demand forecasting nonlinear dynamics genetic algorithm

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Analysis of Chaotic dynamics of Chua's Circuit with lncosh nonlinearity

Analysis of Chaotic Dynamics of Chua's Circuit with lncosh N...

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8th International conference on Electrical and Electronics Engineering (ELECO)

作者： Kocaoglu, Aykut Karal, Omer Guzelis, Cuneyt Dokuz Eylul Univ Izmir Vocat Sch Dept Tech Programs Buca Izmir Turkey Yildirim Beyazit Univ Dept Elect & Telecommun Engn Ankara Turkey Izmir Univ Econ Dept Elect & Telecommun Engn Izmir Turkey

ISBN: (纸本)9786050105049

Chua's circuit, which demonstrates one of the most complicated nonlinear dynamical behaviors, i.e. chaos, contains a three-segment Piecewise Affine (PWA) resistor as the unique nonlinear element. In this study, the non-smooth nonlinearity of Chua's circuit represented by absolute value is approximated with employing the (smooth) lncosh nonlinearity. In contrast to the other smooth approximation, the 1/lambda lncosh (lambda x) approximation has the property of yielding the absolute value nonlinearity |x| as the limit case when lambda parameter goes to infinity. The bifurcation maps and attractors of introduced Chua's circuit obtained for different lambda parameters are presented in the paper in a comparative way. Computer simulations show that lncosh approximation preserves the chaotic behavior and hence provides the possibility of analyzing the behavior of the Chua's circuit by the methods requiring smoothness.

关键词： Timing circuits

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10 GHz bandwidth nonlinear delay electro-optic phase dynamics for ultrafast nonlinear transient computing

10 GHz bandwidth nonlinear delay electro-optic phase dynamic...

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conference on Lasers and Electro-Optics Europe (CLEO EUROPE)

作者： A. Baylón-Fuentes R. Martinenghi M. Jacquot Y. Chembo L. Larger Optics Dpt. University of Franche-Comté & FEMTO-ST Besançon France

ISBN: (纸本)9781479905942

Summary form only given. nonlinear delay dynamical systems have found several fundamental and applied issues in Optics, since delays from time of flight of the light becomes easily important, even with a few cm of fibers, compared to fast or even ultra-fast photonic response times. Fiber pigtailed modern Telecom devices can thus provide easy system design strategies to build well-controlled high complexity nonlinear delay dynamics. Recently in that context, electro-optic phase modulation, combined with an imbalanced Mach-Zehnder DPSK demodulator providing a temporally nonlocal nonlinear phase-to-intensity conversion, together with a delayed optoelectronic feedback loop, was proposed as an efficient optical chaos generator for demonstrating 10 Gb/s optical chaos communications.

关键词： chaos Differential phase shift keying Oscillators Phase modulation Phase space analysis methods Systems design

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