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39th IMAC, A conference and Exposition on Structural dynamics, 2021

作者： Saunders, Brian Evan Vasconcellos, Rui M. G. Kuether, Robert J. Abdelkefi, Abdessattar Mechanical and Aerospace Engineering Department New Mexico State University Las CrucesNM United States Campus of São João da Boa Vista São Paulo State University São João da Boa Vista Brazil Sandia National Laboratories AlbuquerqueNM United States

ISBN: (纸本)9783030771348

Physical systems that are subject to intermittent contact/impact are often studied using piecewise-smooth models. Freeplay is a common type of piecewise-smooth system and has been studied extensively for gear systems (backlash) and aeroelastic systems (control surfaces like ailerons and rudders). These systems can experience complex nonlinear behavior including isolated resonance, chaos, and discontinuity-induced bifurcations. This behavior can lead to undesired damaging responses in the system. In this work, bifurcation analysis is performed for a forced Duffing oscillator with freeplay. The freeplay nonlinearity in this system is dependent on the contact stiffness, the size of the freeplay region, and the symmetry/asymmetry of the freeplay region with respect to the system’s equilibrium. Past work on this system has shown that a rich variety of nonlinear behaviors is present. Modern methods of nonlinear dynamics are used to characterize the transitions in system response including phase portraits, frequency spectra, and Poincaré maps. Different freeplay contact stiffnesses are studied including soft, medium, and hard in order to determine how the system response changes as the freeplay transitions from soft contact to near-impact. Particular focus is given to the effects of different initial conditions on the activation of secondary- and isolated-resonance responses. Preliminary results show isolated resonances to occur only for softer-contact cases, regions of superharmonic resonances are more prevalent for harder-contact cases, and more nonlinear behavior occurs for higher initial conditions. © 2022, The Society for Experimental Mechanics, Inc.

关键词： dynamics

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Deterministic chaos, Bifurcations and Strange Attractors in nonlinear dynamics of Relativistic Backward-Wave Tube 15th

Deterministic Chaos, Bifurcations and Strange Attractors in ...

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15th International conference on Dynamical Systems: Theory and Applications, DSTA 2019

作者： Glushkov, Alexander V. Tsudik, Andrey V. Ternovsky, Valentin B. Astaykin, Dmytro V. Bondarenko, Andrii V. Danylenko, Dmytro V. Buyadzhi, Vasily V. Odessa State Environmental University Odessa Ukraine National University "Odessa Maritime Academy" Odessa Ukraine

ISBN: (纸本)9783030773090

We present the results of modelling, analysis, forecasting the dynamics of relativistic backward-wave tube (RBWT) with accounting for relativistic effects (γ0 = 1.5–6.0), dissipation factor (factor D) and an effect of presence of the space charge. There are computed the temporal dependences of the normalized field amplitudes (power) in a wide range of variation of the controlling parameters (electric length of an interaction space N, bifurcation parameter proportional to current I, the Pirse parameter J and relativistic factor γ0), which are characteristic for distributed relativistic electron-waved self-vibrational systems. The computed temporal dependence of a field amplitude (power) Fmax in a physically reasonable agreement with theoretical estimates and the using the pulsed accelerator "Saturn" experimental data by Ginzburg et al. (IAP, Nizhny Novgorod). The nonlinear analysis technique (including a multi-fractal approach, the methods of correlation integral, false nearest neighbours, surrogate data, the Lyapunov’s exponent’s algorithm and others) is applied to analysis of numerical parameters of the RBWT chaotic dynamics. There are computed the dynamic and topological invariants of the RBWT dynamics in auto-modulation (AUM)/chaotic regimes. The bifurcation diagrams with definition of the dynamics self-modulation/chaotic areas in planes "J-γ0", "D-J" are constructed. © 2021, Springer Nature Switzerland AG.

关键词： dynamics

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Uncertainty Quantification of Loads and Correlated PVs on Power System Dynamic Simulations

Uncertainty Quantification of Loads and Correlated PVs on Po...

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IEEE/IAS conference on Industrial and Commercial Power System Asia (IEEE I and CPS Asia)

作者： Ye, Ketian Zhao, Junbo Duan, Nan Maldonado, Daniel Adrian Mississippi State Univ Dept Elect & Comp Engn Starkville MS 39762 USA Lawrence Livermore Natl Lab Livermore CA 94550 USA Argonne Natl Lab Lemont IL 60439 USA

ISBN: (纸本)9781665434980

This paper proposes a copula-based polynomial chaos expansion (PCE) framework for quantifying correlated uncertain PVs and loads on power system dynamic simulations. The correlations among uncertain PVs are first extracted by copula statistics and further included into the revised PCE formulation. The PCE allows us to conveniently estimate the confidence intervals of system dynamic responses. The effects of different dependence structures of PVs and the number of uncertain sources are investigated using the modified IEEE 39-bus system. Comparison results with other methods show that the proposed method is able to accurately quantify the uncertain dynamic simulations while being computationally efficient.

关键词： Copula statistics nonlinear correlations polynomial chaos expansion power system dynamics PVs uncertainty quantification

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Computation of Positively Invariant Sets of the Duffing System and the nonlinear Pendulum under Bounded Excitation 7

Computation of Positively Invariant Sets of the Duffing Syst...

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7th International conference on Control, Decision and Information Technologies (CoDIT)

作者： Roebenack, Klaus Gerbet, Daniel Tech Univ Dresden Inst Control Theory D-01062 Dresden Germany

ISBN: (纸本)9781728159539

The Duffing system and the nonlinear pendulum are a comparatively simple dynamical systems that can generate complex dynamics such as subharmonics, intermittency and chaos. Both system has been used to model a variety of technical systems, where nonlinear oscillations occur. The dynamics can usually not be computed analytically but only simulated numerically. In this paper we provide a method to compute analytically exact bounds on the trajectories of the excited Duffing system and the nonlinear pendulum. These computations are carried out using quantifier elimination.

关键词： Duffing system nonlinear pendulum positively invariant sets Lyapunov methods quantifier elimination

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Face emotional responses correlate with chaotic dynamics of eye movements. 25

Face emotional responses correlate with chaotic dynamics of ...

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25th KES International conference on Knowledge-Based and Intelligent Information & Engineering Systems (KES)

作者： Sledzianowski, Albert Urbanowicz, Krzysztof Glac, Wojciech Slota, Renata Wojtowicz, Maria Nowak, Monika Przybyszewski, Andrzej Polish Japanese Acad Informat Technol Fac Informat Technol PL-02008 Warsaw Poland Warsaw Univ Technol Fac Phys PL-00661 Warsaw Poland Univ Gdansk Fac Biol Dept Anim & Human Physiol PL-80309 Gdansk Poland Univ Gdansk Student Sci Assoc Homunculus PL-80309 Gdansk Poland

Background and Objective. Paul Ekman has demonstrated that we can estimate emotions on the basis of individual facial muscles movements. However, there is a lack of information in the literature about correlation between eye movements and facial emotions. Our objective was to find out whether emotion could be also visible in the dynamical properties of the eye movements. methods. We have performed our experiment in two sessions related to different video presentations: 1) a reference session with all emotions presentation, and 2) the main session showing presentation of some specific emotions. During both sessions, we have video recordings of the subjects' face expressions (FE) and eye movements (EM). We have calculated parameters of FE and EM dynamical changes and content of the noise. On this basis, by using time changes of EM, we have predicted 6 different face emotions. Results. We have recorded face expressions of 49 subjects who had the strongest responses to Happiness and Contempt facial emotions. We found statistically significant differences in parameters' values describing FE and EM between the reference and the main sessions trials. Parameters connected to the chaos showed highly positive correlations with Happiness, while both the Linear and the Noise components were mostly negatively correlated with this emotion. We achieved highest results with help of the K-Nearest Neighbors algorithm obtaining: Accuracy of 0.89 (+/- 0.01) with the ROC-AUC score of 0.88 (F1 = 0.89), Precision = 0.85, Sensitivity / Recall = 0.93, Specificity = 0.82. Conclusions. We have observed that when the intensity of the Happiness increases, the eye movements become more chaotic and behave less noisy. We see possibilities for use of presented methods as a support for predictions in face expressions, when the lower part of the face is partially hidden, e.g. by a protective mask worn during the COVID epidemic. This could also be a method of confirming the authenticity of the Happine

关键词： machine-learning eye moves empathy face emotions happiness noise chaos nonlinear dynamical systems

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Improvement of random coefficient differential models of growth of anaerobic photosynthetic bacteria by combining Bayesian inference and gPC

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MATHEMATICAL methods IN THE APPLIED SCIENCES 2020年第14期43卷 7885-7904页

作者： Calatayud, Julia Cortes, Juan Carlos Jornet, Marc Univ Politecn Valencia Inst Univ Matemat Multidisciplinar Camino Vera S-N Valencia 46022 Spain

The time evolution of microorganisms, such as bacteria, is of great interest in biology. In the article by D. Stanescu et al. [Electronic Transactions on Numerical Analysis, 34, 44-58 (2009)], a logistic model was proposed to model the growth of anaerobic photosynthetic bacteria. In the laboratory experiment, actual data for two species of bacteria were considered:Rhodobacter capsulatusandChlorobium vibrioforme. In this paper, we suggest a new nonlinear model by assuming that the population growth rate is not proportional to the size of the bacteria population, but to the number of interactions between the microorganisms, and by taking into account the beginning of the death phase in the kinetic curve. Stanescu et al. evaluated the effect of randomness into the model coefficients by using generalized polynomial chaos (gPC) expansions, by setting arbitrary distributions without taking into account the likelihood of the data. By contrast, we utilize a Bayesian inverse approach for parameter estimation to obtain reliable posterior distributions for the random input coefficients in both the logistic and our new model. Since our new model does not possess an explicit solution, we use gPC expansions to construct the Bayesian model and to accelerate the Markov chain Monte Carlo algorithm for the Bayesian inference.

关键词： bacterial growth model Bayesian inverse problem generalized polynomial chaos nonlinear biological model population dynamics

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Theory and methods for Studying the nonlinear dynamics of a Beam-Plate Nano Resonator Taking into Account the Temperature and Strain Fields Connection in Additive Color Noise 27

Theory and Methods for Studying the Nonlinear Dynamics of a ...

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27th Saint Petersburg International conference on Integrated Navigation Systems, ICINS 2020

作者： Papkova, I.V. Krysko, A.V. Krysko, V.A. Yuri Gagarin State Technical University of Saratov Saratov Russia

ISBN: (纸本)9785919950684

A theory of geometrically nonlinear dynamics of nanoplates has been constructed with allowance for the temperature and strain fields connection on the basis of the modified moment theory taking into account the transverse load and additive color noise. A research method based on the qualitative theory of differential equations has been developed. An example of the additive color noise influence on nonlinear vibrations for an elastic Euler-Bernoulli beam is given. © 2020 Concern CSRI Elektropribor, JSC.

关键词： chaos theory

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Improvement of random coefficient differential models of growth of anaerobic photosynthetic bacteria by combining Bayesian inference and gPC

Improvement of random coefficient differential models of gro...

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conference on Mathematical Modelling in Engineering and Human Behaviour

作者： Calatayud, Julia Cortes, Juan Carlos Jornet, Marc Univ Politecn Valencia Inst Univ Matemat Multidisciplinar Camino Vera S-N Valencia 46022 Spain

关键词： bacterial growth model Bayesian inverse problem generalized polynomial chaos nonlinear biological model population dynamics

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Non Contact methods of Heart Rate Variability Measuring and Analysis 25

Non Contact Methods of Heart Rate Variability Measuring and ...

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25th International conference on Applied Electronics (AE)

作者： Stork, Milan Houzar, Josef Univ West Bohemia Dept Appl Elect & Telecommun RICE Plzen Czech Republic

ISBN: (数字)9788026108924

ISBN: (纸本)9788026108924

It is well known that the heart rate variability (HRV) reflects the activity of the autonomic nervous system. HRV is calculated from heart rate (HR). HR is a nonstationary signal;its frequency variation may contain indicators of current disease, or warnings about impending cardiac diseases. Irregular variance of HRV can be considered as a predictor for sudden cardiac death or for cardiac transplant patient, etc. Measurements of HRV can be acquired by analyzing the changes of heart rate with power spectral analysis or obtained from model by using the nonlinear dynamics e.g. chaos theory. This paper deals on different approach for HRV measuring and their properties. All described methods were tested and results are shown.

关键词： accelerometer balistocardiography ECG heart rate variability non contact electrodes pressure wave

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Designing full-order sliding mode controller based on neural network for a class of chaotic systems

Designing full-order sliding mode controller based on neural...

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International conference on Control, Instrumentation, and Automation

作者： Talayeh Karbini Zahra Rahmani Behrooz Rezaie Babol Noshirvani University of Technology Babol Iran

ISBN: (纸本)9781665403504;9781665430012

In this study, Full-order sliding mode control based on neural network is proposed to control chaos in nonlinear systems. At the first, for chaotic systems, a full-order sliding mode controller is designed for chaotic system with uncertainty and disturbance. This method isn't used for chaotic systems. The full-order sliding mode controller is a novel method to design controllers for nonlinear systems in canonical form, which can meet the problem of chattering and singularity existed in sliding mode control methods. Then with the assumption that a part of system dynamic is uncertain Radial basis function (RBF) network is applied for uncertain dynamic estimation of system based on input-output data and a new controller is proposed for chaotic systems. Stability of the proposed method is proved based on Lyapunov theorem. Simulation are carried on a chaotic systems named and the simulation results show appropriate performance of the proposed controller.

关键词： Uncertainty System dynamics Simulation Radial basis function networks Stability analysis nonlinear dynamical systems Sliding mode control

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