Relevant bibliographies by topics / Lyapunov exponents. eng

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  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers

Academic literature on the topic 'Lyapunov exponents. eng'

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Published: 4 June 2021
Last updated: 15 February 2022

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Journal articles on the topic "Lyapunov exponents. eng"

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Kwasniok, Frank. "Fluctuations of finite-time Lyapunov exponents in an intermediate-complexity atmospheric model: a multivariate and large-deviation perspective." Nonlinear Processes in Geophysics 26, no. 3 (July 31, 2019): 195–209. http://dx.doi.org/10.5194/npg-26-195-2019.

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Abstract. The stability properties as characterized by the fluctuations of finite-time Lyapunov exponents around their mean values are investigated in a three-level quasi-geostrophic atmospheric model with realistic mean state and variability. Firstly, the covariance structure of the fluctuation field is examined. In order to identify dominant patterns of collective excitation, an empirical orthogonal function (EOF) analysis of the fluctuation field of all of the finite-time Lyapunov exponents is performed. The three leading modes are patterns where the most unstable Lyapunov exponents fluctuate in phase. These modes are virtually independent of the integration time of the finite-time Lyapunov exponents. Secondly, large-deviation rate functions are estimated from time series of finite-time Lyapunov exponents based on the probability density functions and using the Legendre transform method. Serial correlation in the time series is properly accounted for. A large-deviation principle can be established for all of the Lyapunov exponents. Convergence is rather slow for the most unstable exponent, becomes faster when going further down in the Lyapunov spectrum, is very fast for the near-neutral and weakly dissipative modes, and becomes slow again for the strongly dissipative modes at the end of the Lyapunov spectrum. The curvature of the rate functions at the minimum is linked to the corresponding elements of the diffusion matrix. Also, the joint large-deviation rate function for the first and the second Lyapunov exponent is estimated.
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Dahal, Abinash, Deepashree Devaraj, and Dr N. Pradhan Dr. N. Pradhan. "Topological Characteristics of ECG Signal using Lyapunov Exponent and RBF Network." Indian Journal of Applied Research 1, no. 9 (October 1, 2011): 53–55. http://dx.doi.org/10.15373/2249555x/jun2012/22.

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Yakovleva, Tatiana V., Ilya E. Kutepov, Antonina Yu Karas, Nikolai M. Yakovlev, Vitalii V. Dobriyan, Irina V. Papkova, Maxim V. Zhigalov, et al. "EEG Analysis in Structural Focal Epilepsy Using the Methods of Nonlinear Dynamics (Lyapunov Exponents, Lempel–Ziv Complexity, and Multiscale Entropy)." Scientific World Journal 2020 (February 11, 2020): 1–13. http://dx.doi.org/10.1155/2020/8407872.

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This paper analyzes a case with the patient having focal structural epilepsy by processing electroencephalogram (EEG) fragments containing the “sharp wave” pattern of brain activity. EEG signals were recorded using 21 channels. Based on the fact that EEG signals are time series, an approach has been developed for their analysis using nonlinear dynamics tools: calculating the Lyapunov exponent’s spectrum, multiscale entropy, and Lempel–Ziv complexity. The calculation of the first Lyapunov exponent is carried out by three methods: Wolf, Rosenstein, and Sano–Sawada, to obtain reliable results. The seven Lyapunov exponent spectra are calculated by the Sano–Sawada method. For the observed patient, studies showed that with medical treatment, his condition did not improve, and as a result, it was recommended to switch from conservative treatment to surgical. The obtained results of the patient’s EEG study using the indicated nonlinear dynamics methods are in good agreement with the medical report and MRI data. The approach developed for the analysis of EEG signals by nonlinear dynamics methods can be applied for early detection of structural changes.
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Hajipour, Ahmad, and Hamidreza Tavakoli. "Dynamic Analysis and Adaptive Sliding Mode Controller for a Chaotic Fractional Incommensurate Order Financial System." International Journal of Bifurcation and Chaos 27, no. 13 (December 15, 2017): 1750198. http://dx.doi.org/10.1142/s021812741750198x.

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In this study, the dynamic behavior and chaos control of a chaotic fractional incommensurate-order financial system are investigated. Using well-known tools of nonlinear theory, i.e. Lyapunov exponents, phase diagrams and bifurcation diagrams, we observe some interesting phenomena, e.g. antimonotonicity, crisis phenomena and route to chaos through a period doubling sequence. Adopting largest Lyapunov exponent criteria, we find that the system yields chaos at the lowest order of [Formula: see text]. Next, in order to globally stabilize the chaotic fractional incommensurate order financial system with uncertain dynamics, an adaptive fractional sliding mode controller is designed. Numerical simulations are used to demonstrate the effectiveness of the proposed control method.
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WANG, Zhenzhou. "Lyapunov exponents for synchronous 12-lead ECG signals." Chinese Science Bulletin 47, no. 21 (2002): 1845. http://dx.doi.org/10.1360/02tb9403.

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Wang, Zhenzhou, Zheng Li, Yixiang Wei, Xinbao Ning, and Yuzheng Lin. "Lyapunov exponents for synchronous 12-lead ECG signals." Science Bulletin 47, no. 21 (November 2002): 1845–48. http://dx.doi.org/10.1007/bf03183855.

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Übeyli, Elif Derya. "Detecting variabilities of ECG signals by Lyapunov exponents." Neural Computing and Applications 18, no. 7 (January 8, 2009): 653–62. http://dx.doi.org/10.1007/s00521-008-0229-8.

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BERGAMASCO, L., M. SERIO, A. R. OSBORNE, and L. CAVALERI. "FINITE CORRELATION DIMENSION AND POSITIVE LYAPUNOV EXPONENTS FOR SURFACE WAVE DATA IN THE ADRIATIC SEA NEAR VENICE." Fractals 03, no. 01 (March 1995): 55–78. http://dx.doi.org/10.1142/s0218348x95000060.

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We study wind-driven surface wave data taken on an offshore platform in 16 m of water, about 20 km from Venice in the Northern Adriatic Sea. The data are investigated for the effects of chaos and to this end they are subjected to a variety of time series analysis techniques from the field of dynamical systems theory. For certain data sets we find a finite value for the correlation dimension (~7) and a positive value for the largest Lyapunov exponent (~1.5×10−3 bit/sec). In spite of the fact that these results suggest the possibility of chaotic behavior in the data, the correct interpretation is that the data are essentially stochastic, and that the correlation dimensions and Lyapunov exponents result from the anomalous statistical behavior of certain near-Gaussian random processes whose properties we discuss.
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Übeyli, Elif Derya. "Lyapunov exponents/probabilistic neural networks for analysis of EEG signals." Expert Systems with Applications 37, no. 2 (March 2010): 985–92. http://dx.doi.org/10.1016/j.eswa.2009.05.078.

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GULER, N., E. UBEYLI, and I. GULER. "Recurrent neural networks employing Lyapunov exponents for EEG signals classification." Expert Systems with Applications 29, no. 3 (October 2005): 506–14. http://dx.doi.org/10.1016/j.eswa.2005.04.011.

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Dissertations / Theses on the topic "Lyapunov exponents. eng"

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Ferreira, Marcela Cristiani. "Análise de um sistema dinâmico não ideal com excitação vertical e horizontal /." São José do Rio Preto : [s.n.], 2007. http://hdl.handle.net/11449/94291.

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Orientador: Masayoshi Tsuchida
Banca: Reyolando M.L.R.F. Brasil
Banca: Maurílio Boaventura
Resumo: Neste trabalho realizamos um estudo de um sistema dinâmico não ideal, constituído por um pêndulo acoplado a um bloco e que oscilam verticalmente. A oscilação é devida a rotação de uma massa desbalanceada e acionada por um motor DC, cuja fonte de energia é limitada. Consideramos situações em que as freqüências do bloco e do pêndulo estão em ressonâncias internas 1:1, 1:2 e 2:1, e analisamos o comportamento do sistema bloco- motor-pêndulo através de simulações numéricas. Uma análise similar e levada a efeito, no caso em que o sistema dinâmico é dotado de uma excitação de suporte ideal horizontal do tipo F cos wt.
Abstract: In this work we studied a nonideal dynamical system which is constituted by a pendulum connected to a block, and that oscillates vertically. The oscillation is due to the rotation of a unbalanced mass moved by DC motor with limited power supply. We consider situations where the frequencies of the block and the pendulum are in 1:1, 1:2 and 2:1 internal resonances, and we analyse the behavior of the block - motor - pendulum system through numerical simulations. A similar analysis is performed in the case where the dynamical system has a periodic horizontal oscillation of type F cos wt.
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Tang, Man. "A study of the nonlinear dynamics nature of ECG signals using Chaos theory." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B34624843.

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Tang, Man, and 鄧敏. "A study of the nonlinear dynamics nature of ECG signals using Chaos theory." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B34624843.

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Maron, Guilherme. "Analysis and classification of spatial cognition using non-linear analysis and artificial neural networks." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/88901.

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O principal objetivo do presente trabalho é propor, desenvolver, testar e apresentar um método para a classificação do grau de desenvolvimento da capacidade cognitiva espacial de diferentes indivíduos. 37 alunos de graduação tiveram seus eletroencefalogramas (EEGs) capturados enquanto estavam engajados em tarefas de rotação mental de imagens tridimensionais. Seu grau de desenvolvimento da capacidade cognitiva espacial foi avaliado utilizando-se um teste psicológico BPR-5. O maior expoente de Lyapunov (LLE) foi calculado a partir de cada um dos 8 canais dos EEGs capturados. OS LLEs foram então utilizados como tuplas de entrada para 5 diferentes classificadores: i) perceptron de múltiplas camadas, ii) rede neural artificial de funções de base radial, iii) perceptron votado, iv) máquinas de vetor de suporte, e v) k-vizinhos. O melhor resultado foi obtido utilizando-se uma RBF com 4 clusters e a função de kernel Puk. Também foi realizada uma análise estatística das diferenças de atividade cerebral, baseando-se nos LLEs calculados, entre os dois grupos de interesse: SI+ (indivíduos com um suposto maior grau de desenvolvimento da sua capacidade cognitiva espacial) e SI- (grupo de controle) durante a realização de tarefas de rotação mental de imagens tridimensionais. Uma diferença média de 16% foi encontrada entre os dois grupos. O método de classificação proposto pode vir a contribuir e a interagir com outros processos na analise e no estudo da capacidade cognitiva espacial humana, assim como no entendimento da inteligência humana como um todo. Um melhor entendimento e avaliação das capacidades cognitivas de um indivíduo podem sugerir a este elementos de motivação, facilidade ou de inclinações naturais suas, podendo, provavelmente, afetar as decisões da sua vida e carreira de uma forma positiva.
The main objective of the present work is to propose, develop, test, and show a method for classifying the spatial cognition degree of development on different individuals. Thirty-Seven undergraduate students had their electroencephalogram (EEG) recorded while engaged in 3-D images mental rotation tasks. Their spatial cognition degree of development was evaluated using a BPR-5 psychological test. The Largest Lyapunov Exponent (LLE) was calculated from each of the 8 electrodes recorded in each EEG. The LLEs were used as input for five different classifiers: i) multi-layer perceptron artificial neural network, ii) radial base functions artificial neural network, iii) voted perceptron artificial neural network, iv) support vector machines, and v) K-Nearest Neighbors. The best result was achieved by using a RBF with 4 clusters and Puk kernel function. Also a statistical analysis of the brain activity, based in the calculated LLEs, differences between two interest groups: SI+ (participants with an alleged higher degree of development of their spatial cognition) and SI- (control group) during the performing of mental rotation of tridimensional images tasks was done.. An average difference of 16% was found between both groups. The proposed classification method can contribute and interact with other processes in the analysis and study of human spatial cognition, as in the understanding of the human intelligence at all. A better understanding and evaluation of the cognitive capabilities of an individual could suggest him elements of motivation, ease or natural inclinations, possibly affecting the decisions of his life and carrier positively.
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"Brain Dynamics Based Automated Epileptic Seizure Detection." Master's thesis, 2012. http://hdl.handle.net/2286/R.I.14947.

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abstract: Approximately 1% of the world population suffers from epilepsy. Continuous long-term electroencephalographic (EEG) monitoring is the gold-standard for recording epileptic seizures and assisting in the diagnosis and treatment of patients with epilepsy. However, this process still requires that seizures are visually detected and marked by experienced and trained electroencephalographers. The motivation for the development of an automated seizure detection algorithm in this research was to assist physicians in such a laborious, time consuming and expensive task. Seizures in the EEG vary in duration (seconds to minutes), morphology and severity (clinical to subclinical, occurrence rate) within the same patient and across patients. The task of seizure detection is also made difficult due to the presence of movement and other recording artifacts. An early approach towards the development of automated seizure detection algorithms utilizing both EEG changes and clinical manifestations resulted to a sensitivity of 70-80% and 1 false detection per hour. Approaches based on artificial neural networks have improved the detection performance at the cost of algorithm's training. Measures of nonlinear dynamics, such as Lyapunov exponents, have been applied successfully to seizure prediction. Within the framework of this MS research, a seizure detection algorithm based on measures of linear and nonlinear dynamics, i.e., the adaptive short-term maximum Lyapunov exponent (ASTLmax) and the adaptive Teager energy (ATE) was developed and tested. The algorithm was tested on long-term (0.5-11.7 days) continuous EEG recordings from five patients (3 with intracranial and 2 with scalp EEG) and a total of 56 seizures, producing a mean sensitivity of 93% and mean specificity of 0.048 false positives per hour. The developed seizure detection algorithm is data-adaptive, training-free and patient-independent. It is expected that this algorithm will assist physicians in reducing the time spent on detecting seizures, lead to faster and more accurate diagnosis, better evaluation of treatment, and possibly to better treatments if it is incorporated on-line and real-time with advanced neuromodulation therapies for epilepsy.
Dissertation/Thesis
M.S. Electrical Engineering 2012
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Book chapters on the topic "Lyapunov exponents. eng"

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Roca González, Joaquín, M. Vallverdú-Ferrer, P. Caminal-Magrans, F. Martínez-González, J. Roca-Dorda, and J. A. Álvarez-Gómez. "Effects of propofol anesthesia on nonlinear properties of EEG: Lyapunov exponents and short-term predictability." In IFMBE Proceedings, 1272–75. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-89208-3_303.

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Fiasché, Maurizio, Lino Nobili, and Bruno Apolloni. "A Comparison between the Use of ESNN on Long Stereo-EEG Recordings and Their Largest Lyapunov Exponent Profiles for Epileptic Brain Analysis." In Neural Information Processing, 545–52. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-42054-2_68.

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Hosseini, Seyyed Abed, Mohammed-Reza Akbarzadeh-T, and Mohammed-Bagher Naghibi-Sistani. "Methodology for Epilepsy and Epileptic Seizure Recognition using Chaos Analysis of Brain Signals." In Intelligent Technologies and Techniques for Pervasive Computing, 20–36. IGI Global, 2013. http://dx.doi.org/10.4018/978-1-4666-4038-2.ch002.

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A novel combination of chaotic features and Adaptive Neuro-Fuzzy Inference System (ANFIS) is proposed for epileptic seizure recognition. The non-linear dynamics of the original EEGs are quantified in the form of the Hurst exponent (H), Correlation dimension (D2), Petrosian Fractal Dimension (PFD), and the Largest lyapunov exponent (?). The process of EEG analysis consists of two phases, namely the qualitative and quantitative analysis. The classification ability of the H, D2, PFD, and ? measures is tested using ANFIS classifier. This method is evaluated with using a benchmark EEG dataset, and qualitative and quantitative results are presented. The inter-ictal EEG-based diagnostic approach achieves 98.6% accuracy with using 4-fold cross validation. Diagnosis based on ictal data is also tested in ANFIS classifier, reaching 98.1% accuracy. Therefore, the method can be successfully applied to both inter-ictal and ictal data.
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Escobar, Eder, Richard Abramonte, Antenor Aliaga, and Flabio Gutierrez. "An Octave Package to Perform Qualitative Analysis of Nonlinear Systems Immersed in R4." In Machine Learning and Artificial Intelligence. IOS Press, 2020. http://dx.doi.org/10.3233/faia200775.

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In this work, the AutonomousSystems4D package is presented, which allows the qualitative analysis of non-linear differential equation systems in four dimensions, as well as drawing the phase surfaces by immersing R4 in R3. The package is programmed in the computational tool Octave. As a case study applied to the new Lorenz 4D System, sensitivity was found in the initial conditions, Lyapunov exponents, Kaplan Yorke dimension, a stable and unstable critical point, limit cycle, Hopf bifurcation, and hyperattractors. The package could be adapted to perform qualitative analysis and visualize phase surfaces to autonomous systems, e.g. Sprott 4D, Rossler 4D, etc. The package can be applied to problems such as: design, analysis, implementation of electronic circuits; to message encryption.
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Pham, Viet-Thanh, Christos Volos, and Sundarapandian Vaidyanathan. "Chaotic Attractor in a Novel Time-Delayed System with a Saturation Function." In Handbook of Research on Advanced Intelligent Control Engineering and Automation, 230–58. IGI Global, 2015. http://dx.doi.org/10.4018/978-1-4666-7248-2.ch008.

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From the viewpoint of engineering applications, time delay is useful for constructing a chaotic signal generator, which is the major part of diverse potential applications. Although different mathematical models of time-delay systems have been known, few models can exhibit chaotic behaviors. Motivated by attractive features and potential applications of time-delay models, a new chaotic system with a single scalar time delay and a nonlinearity described by a saturation function is proposed in this chapter. Nonlinear behavior of the system is discovered through bifurcation diagrams and the maximum Lyapunov exponent with the variance of system parameters. Interestingly, the system shows double-scroll chaotic attractors for some suitable chosen system parameters. In order to confirm the correction and feasibility of the theoretical model, the system is also implemented with analog electronic circuit. Finally, a practical application of such circuit is discussed at the end of this chapter.
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Conference papers on the topic "Lyapunov exponents. eng"

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Mayer-Kress, G. "Fractal dimensions, Lyapunov exponents, and predictability of human EEG signals." In Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE, 1988. http://dx.doi.org/10.1109/iembs.1988.94973.

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Kang, Jae-Hwan, Chung Ho Lee, and Sung-Phil Kim. "EEG feature selection and the use of Lyapunov exponents for EEG-based biometrics." In 2016 IEEE-EMBS International Conference on Biomedical and Health Informatics (BHI). IEEE, 2016. http://dx.doi.org/10.1109/bhi.2016.7455876.

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Liu, Chang-Chia, Deng-Shan Shiau, W. Art Chaovalitwongse, Panos M. Pardalos, J. C. Sackellares, Onur Seref, O. Erhun Kundakcioglu, and Panos Pardalos. "Presence of nonlinearity in intracranial EEG recordings: detected by Lyapunov exponents." In DATA MINING, SYSTEMS ANALYSIS AND OPTIMIZATION IN BIOMEDICINE. AIP, 2007. http://dx.doi.org/10.1063/1.2817342.

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Dahal, Prawesh, Mariam Avagyan, Per Sebastian Skardal, Harry J. Blaise, and Taikang Ning. "Characterizing chaotic behavior of REM sleep EEG using Lyapunov exponent." In 2017 10th International Congress on Image and Signal Processing, BioMedical Engineering and Informatics (CISP-BMEI). IEEE, 2017. http://dx.doi.org/10.1109/cisp-bmei.2017.8302215.

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Arnold, Ludwig, Peter Imkeller, and N. Sri Namachchivaya. "The Asymptotic Stability of Weakly Perturbed Two Dimensional Hamiltonian Systems." In ASME 2001 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/detc2001/vib-21593.

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Abstract The purpose of this work is to obtain an approximation for the top Lyapunov exponent, the exponential growth rate, of the response of a single-well Kramers Oscillator driven by either a multiplicative or an additive white noise process. To this end, we consider the equations of motion as dissipative and noisy perturbations of a two-dimensional Hamiltonian system. A perturbation approach is used to obtain explicit expressions for the exponent in the presence of small intensity noise and small dissipation. We show analytically that the top Lyapunov exponent is positive, and for small values of noise intensity ε and dissipation ε the exponent grows proportional to ε1/3.
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Nagai, Ken-ichi, Shinichi Maruyama, Kazuya Sakaimoto, and Takao Yamaguchi. "Chaotic Oscillations of a Post-Buckled Beam Constrained by an Axial Spring: Part 1 — Experiment." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-61352.

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Experimental results are presented on chaotic oscillations of a post-buckled beam subjected to periodic lateral acceleration. A thin steel beam of thickness 0.198mm, breath 12.7 mm and length 106mm is used as a test beam. Both ends of the beam are clamped and one end is connected to an axial spring. First, natural frequencies of the beam are measured under an axial compression. Under the post-buckled configuration of the beam, characteristics of static deflection by a concentrated load on the beam are obtained. The post-buckled beam shows the soften-and-hardening characteristics of restoring force. The frequency regions of chaotic responses are inspected. The chaotic responses around these domains are examined carefully by time histories, the Poincare´ maps, the Fourier spectra, the maximum Lyapunov exponents and the principal component analysis. The predominant chaotic responses of the beam are generated by the jump phenomena. The chaotic responses are related to the sub-harmonic resonances of 1/2 and 1/3 orders with the lowest mode of vibration. The maximum Lyapunov exponent of the former chaotic response of 1/2 order is larger than that of the latter chaotic response of 1/3 order. Onsets of the chaotic responses are also confirmed by the Poincare´ projection in the variation of exciting frequency.
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Nguyen, Son Hai, and David Chelidze. "Characteristic Lengths and Distances: Fast and Robust Features for Nonlinear Time Series." In ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-71281.

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Estimation of most of the metrics used to characterize dynamical systems’ output require fairly long time series (e.g., Lyapunov Exponents, Fractal Dimensions), or substantial computational resources (e.g., phase space warping metrics, sensitivity vector fields). In many practical applications, when there is abundance of data (e.g., in Atomic Force Microscopy) fast and simple features are needed, and when there is sparsity of data (e.g., in many Structural Health Monitoring situations) robust features are needed. Here, we propose a new class of features based on Birkhoff Ergodic Theorem, which are fast to calculate and do not require large data or computational resources. Applications of these metrics, in conjunction with the smooth orthogonal decomposition, to identifying underlying processes causing nonstationarity both in simulations and actual experiments are demonstrated.
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Кутепов, Илья, Ilya Kutepov, Вадим Крысько, Vadim Krysko, Антон Крысько, Anton Krysko, Сергей Павлов, et al. "Complexity of EEG Signals in Schizophrenia Syndromes." In 29th International Conference on Computer Graphics, Image Processing and Computer Vision, Visualization Systems and the Virtual Environment GraphiCon'2019. Bryansk State Technical University, 2019. http://dx.doi.org/10.30987/graphicon-2019-2-140-143.

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In the present study, 45 patients with schizophrenia syndromes and 39 healthy subjects are studied with electroencephalogram (EEG) signals. The study groups were of different genders. For each of the two groups, the signals were analyzed using 16 EEG channels. Multiscale entropy, Lempel-Ziv complexity and Lyapunov exponent were used to study the chaotic signals. The data were compared for two groups of subjects. Entropy was compared for each of the 16 channels for all subjects. As a result, topographic images of brain areas were obtained, illustrating the entropy and complexity of Lempel-Ziv. Lempel-Ziv complexity was found to be more representative of the classification problem. The results will be useful for further development of EEG signal classification algorithms for machine learning. This study shows that EEG signals can be an effective tool for classifying participants with symptoms of schizophrenia and control group. It is suggested that this analysis may be an additional tool to help psychiatrists diagnose patients with schizophrenia.
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Marghitu, Dan B., Steven F. Swaim, Paul F. Rumph, Dorian Cojocaru, Robert L. Gillette, and M. Stacie Scardino. "Contact Pressure of Quadrupedal Animals." In ASME 2003 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/detc2003/vib-48427.

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In this study we determine the pressure on the central area of each of the weight bearing pads of the paws of dogs at the walk. Pressure signal data from stance phase during walking were analyzed. Within paws, there were significant pressure differences among pads on both fore and hind limbs. The coefficient of restitution, the embedding dimension, and the Lyapunov exponents were calculated. The ability to measure and analyze pressure on individual paw pads provides insight into soft tissue stresses on the palmar/plantar surface of the paw. Pressure at a wound site on the pads has a detrimental effect on wound healing and a better understanding these stresses will be of benefit when suturing and bandaging pad wounds. Such information is especially important in athletic and working dogs, e.g. search and rescue dogs.
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Tamer, Aykut, and Pierangelo Masarati. "Helicopter Ground Resonance Investigation With Dissimilar Nonlinear Lead-Lag Dampers." In ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/detc2015-46809.

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This work describes the analysis of helicopter ground resonance when nonlinearity and non-isotropy of the problem are taken into account. Ground resonance is a dynamic instability caused by the interaction between the rotor and the airframe of a helicopter. Sources of nonlinearity can be geometrical (finite blade lead-lag motion) and constitutive (hydraulic lead-lag dampers and shock absorbers). Standard methods use special coordinate transformations that make it possible to cast the problem in linear, time invariant form when considering small oscillations of an isotropic rotor about a reference solution. However, potential non-isotropy of the rotor (e.g. resulting from degraded performance of lead-lag dampers) may turn the problem into linear, time periodic. In such cases, the Floquet-Lyapunov method is normally used to study the stability of the coupled system. In this work the problem is investigated using Lyapunov Characteristic Exponents (LCE). The analysis shows that in some cases, characterized by a marked contribution of the nonlinearity of the blade lead-lag dampers, the problem assumes a nearly chaotic behavior. The stability of the system is investigated, and the sensitivity of the LCEs with respect to system parameters is determined, in an attempt to provide a consistent analysis framework and useful design guidelines.
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