Chaos and chaotic transients in an aeroelastic system

Chaotic motions of a two dimensional airfoil with coupled structural nonlinearities, both in pitch as well as plunge degrees of freedom, are investigated via a numerical integration method. The original system of coupled integro-differential equations governing the motion of the present aeroelastic model is transformed into a simple system of six ordinary differential equations (ODEs), rather than the previously frequently used eight ODEs. Complex dynamical behaviors are revealed and identified through the means of bifurcation diagrams, the phase portraits, the amplitude spectra and the Poincare maps. Besides, a more quantitative method, namely that of observing the evolution of the largest Lyapunov exponent (LLE) is also applied to diagnose the motions. Two peculiar phenomena, namely, long (perhaps super-persistent) chaotic transients, and fluctuating Lyapunov exponents, are observed; in the two such cases the LLE method fails to work. In addition, the effects of various system parameters, namely, the position of the elastic axis, the frequency ratio, the airfoil/air mass ratio, the viscous damping ratios, and the location of the center of mass, on the response of the aeroelastic system, are investigated.     

Intra- and intersubject variability in acoustic measures of normal voice

Twenty-four normal adult women read part of the Rainbow Passage and sustained vowels three trials each. Utterances were assessed for selected parameters measured by Visi-Pitch (average and SD of fundamental frequency (F₀), average and SD of dBA, perturbation, and percent voiced/unvoiced/pause). Assessment of each parameter included measures of central tendency, dispersion, and distribution characteristics (skewness and kurtosis) of the data and of the ranges of values that would include 95% of the scores (95% fiduciary limits). Generally, differences for the group between the three trials were not significant. Intersubject variability for only a few parameters was less than 20% of the parameter's mean. For vowels, variability of jitter was 30–48% of the mean. Eight subjects provided performances 2 months later to obtain an estimate of intrasubject variability over time. There were desirable intrasubject correlations between performances for mean F₀, jitter in reading and on vowels /i/ and /a/, and percent of voicing. Inter- and intrasubject variability seems restricted and the data appear to resemble a normally distributed function for mean F₀ on reading, jitter on /i/, and percent of voicing. Thus, these parameters may have statistical merit for use in vocal testing.     

激发核系统中最大Lyapunov指数、密度涨落以及多重碎裂之间的关系

基于量子分子动力学模型,系统地研究了从48Ca到298114一系列核素在不同温度下的最大Lyapunov指数、密度涨落以及体系多重碎裂之间的关系.发现最大Lyapunov指数随温度变化有一峰值出现(该峰值所对应的温度为"临界温度"),在该临界温度时体系的密度涨落达到最大,碎块的质量分布能够给出较好的PowerLaw指数.通过对最大Lyapunov指数与密度涨落随时间变化行为的研究,发现密度涨落的时间尺度要大于混沌的时间尺度,意味着混沌的概念可以用来研究体系的多重碎裂过程.最后还给出了有限体系相变的临界温度随体系大小变化的规律. Within a quantum molecular dynamics model we calculate the largest Lyapunov exponent (LLE), the density fluctuation, and the mass distribution of fragments for a series of nuclear systems at different initial temperatures. It is found that the LLE peaks at the temperature ("critical temperature") where the density fluctuation reaches a maximal value and the mass distribution fragments is fitted best by the Fisher s power law from which the critical exponents for mass and charge distribution are obtain...     

A novel four-wing non-equilibrium chaotic system and its circuit implementation

In this paper, we construct a novel, 4D smooth autonomous system. Compared to the existing chaotic systems, the most attractive point is that this system does not display any equilibria, but can still exhibit four-wing chaotic attractors. The proposed system is investigated through numerical simulations and analyses including time phase portraits, Lyapunov exponents, bifurcation diagram, and Poincaré maps. There is little difference between this chaotic system without equilibria and other chaotic systems with equilibria shown by phase portraits and Lyapunov exponents. But the bifurcation diagram shows that the chaotic systems without equilibria do not have characteristics such as pitchfork bifurcation, Hopf bifurcation etc. which are common to the normal chaotic systems. The Poincaré maps show that this system is a four-wing chaotic system with more complicated dynamics. Moreover, the physical existence of the four-wing chaotic attractor without equilibria is verified by an electronic circuit.     

Hysteresis-induced bifurcation and chaos in a magneto-rheological suspension system under external excitation

The magneto-rheological damper(MRD) is a promising device used in vehicle semi-active suspension systems, for its continuous adjustable damping output. However, the innate nonlinear hysteresis characteristic of MRD may cause the nonlinear behaviors. In this work, a two-degree-of-freedom(2-DOF) MR suspension system was established first, by employing the modified Bouc–Wen force–velocity(F –v) hysteretic model. The nonlinear dynamic response of the system was investigated under the external excitation of single-frequency harmonic and bandwidth-limited stochastic road surface.The largest Lyapunov exponent(LLE) was used to detect the chaotic area of the frequency and amplitude of harmonic excitation, and the bifurcation diagrams, time histories, phase portraits, and power spectrum density(PSD) diagrams were used to reveal the dynamic evolution process in detail. Moreover, the LLE and Kolmogorov entropy(K entropy) were used to identify whether the system response was random or chaotic under stochastic road surface. The results demonstrated that the complex dynamical behaviors occur under different external excitation conditions. The oscillating mechanism of alternating periodic oscillations, quasi-periodic oscillations, and chaotic oscillations was observed in detail. The chaotic regions revealed that chaotic motions may appear in conditions of mid-low frequency and large amplitude, as well as small amplitude and all frequency. The obtained parameter regions where the chaotic motions may appear are useful for design of structural parameters of the vibration isolation, and the optimization of control strategy for MR suspension system.     

Hearing Aid Use and Auditory Verbal Therapy Improve Voice Quality of Deaf Children

BackgroundAdequate phonation is self-regulated by auditory feedback. Children with bilateral profound hearing loss (PHL) lack this feedback resulting in abnormal voice. Adequate hearing aid use and auditory-verbal therapy (AVT) may improve voice quality in deaf children.ObjectiveTo study whether hearing aid use and AVT approach improve acoustic parameters of voice of children with bilateral PHL.Materials and methodsNineteen children with bilateral PHL were studied. Age range 2–5 years (X = 53.04 months; SD = 9.54). All children were fitted with hearing aids according to auditory testing and they underwent a 1-year auditory habilitation period using the AVT approach. Acoustic analysis of voice including F0, shimmer, and jitter was performed at the onset and at the end of the auditory habilitation period. Final acoustic data were compared to a matched control group of 19 children, age range 2–5 years (X = 52.85; SD = 9.74) with normal hearing.ResultsMean fundamental frequency (F0) was significantly increased after AVT intervention. Shimmer and jitter significantly (P < 0.05) improved after the intervention period. However, despite the improvements, mean F0 at the end of the intervention period was still significantly (P < 0.05) decreased as compared to controls. Also, mean shimmer and jitter at the end of the habilitation period were still significantly (P < 0.05) higher as compared to controls.ConclusionsThe results of this preliminary study suggest that hearing aid use and auditory habilitation with AVT approach improved acoustic voice parameters of children with PHL. However, acoustic parameters persisted abnormal as compared to matched normal hearing controls. AVT approach and regular hearing aid use seem to be safe and reliable clinical tools for improving voice quality of children with PFL.     

Chaos in the perturbed Korteweg-de Vries equation with nonlinear terms of higher order

The dynamical behaviour of the generalized Korteweg-de Vries (KdV) equation under a periodic perturbation is investigated numerically. The bifurcation and chaos in the system are observed by applying bifurcation diagrams, phase portraits and Poincaré maps. To characterise the chaotic behaviour of this system, the spectra of the Lyapunov exponent and Lyapunov dimension of the attractor are also employed.     

Objective Voice Analysis for Dysphonic Patients: A Multiparametric Protocol Including Acoustic and Aerodynamic Measurements

The purpose was to determine the clinical value of a multiparametric objective voice evaluation protocol including acoustic and aerodynamic parameters measured mainly on a sustained /a/. This was done by comparison with perceptual analysis of continuous speech by a jury composed of 6 experienced listeners. Voice samples (continuous speech) from 63 male patients with dysphonia and 21 control subjects with normal voices were recorded and assesed by a jury of listeners. The jury was instructed to classify voice samples according to the G (overall dysphonia) component of the GRBAS score on a 4-point scale ranging from 0 for normal to 3 for severe dysphonia. Objective parameters were recorded on an EVA^® workstation. As usual with this type of system, parameters were measured mainly on a sustained /a/. Measured parameters included fundamental frequency (F₀), intensity, jitter, shimmer, signal-to-noise ratio, Lyapunov coefficient (LC), oral airflow (OAF), maximum phonatory time (MPT), and vocal range (range). Estimated subglottic pressure (ESGP) was determined on a series of /pa/. Discriminant analysis was performed to detect correlation between jury classification and combinations of parameters. Results showed that a nonlinear combination of only six parameters (range, LC, ESGP, MPT, signal-to-noise ratio, and F₀) allowed 86% concordance with jury classification. Discussion deals with the relative importance of the different objective parameters for discriminant analysis. Special emphasis is placed on two measurements rarely made in routine clinical workup, i.e., estimated subglottic pressure and Lyapunov coefficient.     

利用随机相位实现Duffing系统的混沌控制

基于线性随机系统Khasminskii球面坐标变换, 计算了谐和激励中含有随机相位的Duffing 方程的最大Lyapunov指数. 依据平均最大Lyapunov指数符号的变化, 分析随机相位对非线性系统动力学行为的影响.说明随机相位可以产生混沌亦可抑制混沌, 从而可以作为混沌控制的一种方法. 结合对相图、Poincaré截面、时间历程图的分析, 说明上述方法是有效的. 关键词： 随机相位 混沌控制 最大Lyapunov指数 Poincaré截面     

Clinical Analysis of Voice Change as a Parameter of Premenstrual Syndrome

We have evaluated the relationship between voice change and premenstrual syndrome (PMS) by comparing acoustic measurements made during the follicular phase and the premenstrual phase. Twenty-eight women were followed for 2 months for this study. Each participant was asked to produce an /a/ sound for 5 seconds at the midfollicular phase of the menstrual cycle and then 2-3 days before menstruation. Each voice sample was stored and analyzed by the Dr. Speech Science program. The voice data collected from all subjects during the two phases were compared. After that, the subjects were divided into a PMS-positive and PMS-negative group according to the criteria cited in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV); the voice data from each group were compared separately between the two phases. There was no significant difference in the acoustic parameters between the two phases in all subjects (N = 28). In the PMS-positive group (N = 16), jitter was significantly increased during the premenstrual phase compared to the follicular phase (p = 0.048). The patient's PMS score was not correlated with the severity of voice change. We conclude that the change of voice parameter was objectively identified in the PMS-positive group, therefore more careful voice habituation is required during the premenstrual phase in that group.     

Numerical simulation of unsteady 3D magneto-Sisko fluid flow with nonlinear thermal radiation and homogeneous–heterogeneous chemical reactions

In this paper, we study the qualitative behaviour of satellite systems using bifurcation diagrams, Poincaré section, Lyapunov exponents, dissipation, equilibrium points, Kaplan–Yorke dimension etc. Bifurcation diagrams with respect to the known parameters of satellite systems are analysed. Poincaré sections with different sowing axes of the satellite are drawn. Eigenvalues of Jacobian matrices for the satellite system at different equilibrium points are calculated to justify the unstable regions. Lyapunov exponents are estimated. From these studies, chaos in satellite system has been established. Solution of equations of motion of the satellite system are drawn in the form of three-dimensional, two-dimensional and time series phase portraits. Phase portraits and time series display the chaotic nature of the considered system.     

Willis环脑动脉瘤系统的混沌分析及随机相位控制

研究了Willis环脑动脉瘤系统各参量对系统的影响.计算了含有随机相位的Willis环脑动脉瘤系统的Lyapunov指数,分析了随机相位和不同噪声强度对Willis环脑动脉瘤系统的影响.对相图、Poincaré截面的分析表明,可以利用随机相位对Willis环脑动脉瘤系统进行控制.     

Chaotic behaviour from smooth and non-smooth optical solitons under external perturbation

Smooth and non-smooth optical solitons in the nonlinearly dispersive Schrödinger equation are given by phase portraits. The Melnikov technique is used to detect conditions for chaotic motion of this deterministic system and to analyse conditions for the suppression of chaos. Our results show that the system is in a state of Melnikov chaos by external disturbances. After the implementation of the controlled system, the optical solitons can transmit in a stable station for a long time. Numerical simulation also shows that maximum interference frequency of the system enables the dynamic behaviour to be more complex. The effect of controller parameter on phase portraits as well as on the numerical simulations of bifurcation diagram and maximum Lyapunov exponents are also investigated.     

Chaos Control for Coupling of the Double-Well Duffing System Based on Random Phase Disturbance

Non-feedback methods of chaos control are suited for practical applications. For possible practical applications of the control methods, the robustness of the methods in the presence of noise is of special interest. The noise can be in the form of external disturbances to the system or in the form of uncertainties due to inexact model of the system. This paper deals with the effect of random phase disturbance for a class of coupling of the Double-Well Duffing system in the presence of the noise. Lyapunov index is an important indicator to describe chaos. When the sign of the top Lyapunov exponent is positive, the system is chaotic. We compute top Lyapunov exponent by the Khasminskii’s transform formula of spherical coordinate and extension of Wedig’s algorithm based on linear stochastic system. With the change of the average of top Lyapunov exponent sign, we show that random phase can suppress chaos. Finally Poincaré map and phase portraits analysis are studied to confirm the obtained results.     

Self-reported Voice-related Quality of Life in Adolescents With Paradoxical Vocal Fold Dysfunction

Paradoxical vocal fold dysfunction (PVFD) is a complex disorder of the larynx that primarily affects breathing. To date, no study has focused on the patient's own perception of how their quality of life related to voice is affected by the diagnosis of PFVD. The objective of this study is to characterize the self-reported voice-related quality of life (VR-QOL) patients diagnosed with PVFD using the Pediatric Voice Outcomes Survey (PVOS) instrument; an additional objective was to assess for the presence of any associations between laryngeal findings, concomitant medical disorders, and PVOS measures. The method used was a retrospective chart review. Twenty patients are identified in the study period; there were 17 females (mean age 14 years) and three males (mean age 11 years). The mean PVOS scores are uniformly normal for the subset of boys (n=3, mean PVOS 100). The mean PVOS for the 17 females was 89 (SD, 12.8), lower than that measured in healthy, age-matched females (n=13) who had a mean PVOS of 95 (SD, 7.4). The difference between these two groups was not statistically significant (P<0.17, unpaired t test). Although the absolute PVOS scores were affected by observed laryngeal abnormalities, asthma history, or reflux history, the absence of any of these were significantly more likely to be associated with a perfect score on the PVOS. The overall PVOS does not show a significant decline in the self-reported VR-QOL. Several cofactors may be associated with the detectable but not significant reduction in the PVOS scores for the females in this study.     

Dynamics analysis and synchronization of a new chaotic attractor

In this paper, a new simple chaotic system is discussed. Basic dynamical properties of the new attractor are demonstrated in terms of phase portraits, equilibria and stability, Lyapunov exponents, a dissipative system, Poincaré mapping, bifurcation diagram, especially Hopf bifurcation. Next, based on well-known Lyapunov stability theorem, backstepping design is proposed for synchronization of the new chaotic system. At last, numerical studies are provided to illustrate the effectiveness of the presented scheme.     

Chaos and Hyperchaos in a Backward-Wave Oscillator

Based on a numerical solution of the equations of the nonstationary nonlinear theory, we study chaotic self-oscillation regimes in a backward-wave oscillator. For “weak” chaos, arising via a period-doubling cascade of self-modulation for moderate values of the normalized-length parameter, and for developed chaos, which corresponds to large values of this parameter, we present the temporal dependences of the output-signal amplitude, the phase portraits, and the statistical parameters of the dynamics. It is shown that developed chaos is characterized by the presence of more than one positive Lyapunov exponent (hyperchaos). We also present estimates of the Kolmogorov–Sinai entropy, the Lyapunov dimension, and the correlation dimension obtained from the Grassberger–Procaccia algorithm. The results confirm that a finite-dimensional strange attractor is responsible for the chaotic regimes in a backward-wave oscillator.     

基于高光谱散射图像技术的UVE-LLE苹果粉质化分类

利用高光谱散射图像技术研究了苹果的粉质化无损检测.提出了一种无信息变量消除法和局部线性嵌入相结合的苹果粉质化分类的新方法.经无信息变量消除法筛选后的波段降为全谱的23.5%.将波段选择后的原始图像数据用局部线性嵌入降维作为偏最小二乘判别分析的输入变量并建模.无信息变量消除法与局部线性嵌入相结合算法和局部线性嵌入降维方法得到的粉质化分类测试准确度分别是79.0%和79.0%|无信息变量消除法与平均反射法相结合和平均反射法特征提取得到的是77.4%和75.8%.结果表明,无信息变量消除法与局部线性嵌入想结合的方法可以大大地降低高光谱散射图像的数据量,同时保证了分类准确度,为在线检测、分类和高光谱数据的存储提供了一种实时、有效的方法.