Irregular Vibrations Research Articles

Recurrence analysis and phase space reconstruction of irregular vibration in friction brakes: Signatures of chaos in steady sliding

Irregular friction brake vibration data have been collected with sampling rates of up to 200kHz. The measured time series have been subjected to recurrence analysis and phase space reconstruction. The recurrence analysis indicates that irregular vibration states of friction brakes are strongly dominated by intermittency phenomena. Phase space reconstruction suggests that this intermittency is dominated by low-dimensional irregular deterministic dynamics rather than by high-dimensional stochastic processes.

Noninvasive Monitoring of Vocal Fold Vertical Vibration Using The Acoustic Doppler Effect

To validate a proposed method of noninvasively monitoring vocal fold vertical vibration through utilization of the acoustic Doppler effect and the waveguide property of the vocal tract. Validation case-control study. In this device, an ultrasound beam is generated and directed into the mouth. The vocal tract, acting as a natural waveguide, guides the ultrasound beam toward the vibrating vocal folds. The vertical velocity of vocal fold vibration is then recovered from the Doppler frequency of the reflected ultrasound. One subject (age 32, male) was studied and measurements were taken under three modes of vocal fold vibration: breathing (no vibration), whispering (irregular vibration), and normal phonation (regular vibration). The peak-to-peak amplitude of the measured velocity of vocal fold vertical vibration was about 0.16 m/s, and the fundamental frequency was 172 Hz; the extracted velocity information showed a reasonable waveform and value in comparison with the previous studies. In all three modes of phonation, the Doppler frequencies derived from the reflected ultrasound corresponded with the vertical velocity of vocal fold vibration as expected. The proposed method can accurately represent the characteristics of different phonation modes such as no phonation, whisper and normal phonation. The proposed device could be used in daily monitoring and assessment of vocal function and vocal fold vibration.

Two Dimensional Bistable Vibration Energy Harvester

Abstract In this paper a new strategy for broadband, bi-directional, vibration energy harvester is presented. Often energy harvesting systems address unidirectional incoming energy, however this is a strong limitation when considering real applications; in fact it is very likely that incoming vibrations will not be aligned with the direction of motion of the harvester. Irregular vibrations along several orientations reduce the energy conversion and the harvester efficiency. A suitable harvester architecture for collecting energy from vibrations distributed along different directions is needed. Furthermore, often the ambient vibrations come with energy distributed over a wide spectrum of frequencies, with predominance of low frequency components. This work addresses both these issues by proposing a nonlinear bistable oscillator based on two-dimensional, magnetically-coupled, PZT-based beams able to extract energy from ambient vibrations with arbitrary directions. The basic idea will be presented together with the experimental prototype realized and the results obtained.

ON REGULAR AND IRREGULAR NONLINEAR VIBRATIONS IN TORSIONAL DISCRETE-CONTINUOUS SYSTEMS

The paper deals with regular and irregular nonlinear vibrations of discrete-continuous systems torsionally deformed. The systems consist of an arbitrary number of shafts connected by rigid bodies. In the systems, a local nonlinearity having a soft type characteristic is introduced. This nonlinearity is described by the polynomial of the third degree. General governing equations using the wave approach are derived for a multimass system. Detailed numerical considerations are presented for a two-mass system and a three-mass system. The possibility of occurrence of irregular vibrations is discussed on the basis of the Poincaré maps and bifurcation diagrams.

Piezoelectric MEMS Energy Harvester for Low-Frequency Vibrations With Wideband Operation Range and Steadily Increased Output Power

A piezoelectric MEMS energy harvester (EH) with low resonant frequency and wide operation bandwidth was designed, microfabricated, and characterized. The MEMS piezoelectric energy harvesting cantilever consists of a silicon beam integrated with piezoelectric thin film (PZT) elements parallel-arranged on top and a silicon proof mass resulting in a low resonant frequency of 36 Hz. The whole chip was assembled onto a metal carrier with a limited spacer such that the operation frequency bandwidth can be widened to 17 Hz at the input acceleration of 1.0 g during frequency up-sweep. Load voltage and power generation for different numbers of PZT elements in series and in parallel connections were compared and discussed based on experimental and simulation results. Moreover, the EH device has a wideband and steadily increased power generation from 19.4 nW to 51.3 nW within the operation frequency bandwidth ranging from 30 Hz to 47 Hz at 1.0 g. Based on theoretical estimation, a potential output power of 0.53 μW could be harvested from low and irregular frequency vibrations by adjusting the PZT pattern and spacer thickness to achieve an optimal design.

Effects of poroelastic coefficients on normal vibration modes in vocal-fold tissues

The vocal-fold tissue is treated as a transversally isotropic fluid-saturated porous material. Effects of poroelastic coefficients on eigenfrequencies and eigenmodes of the vocal-fold vibration are investigated using the Ritz method. The study demonstrates that the often-used elastic model is only a particular case of the poroelastic model with an infinite fluid-solid mass coupling parameter. The elastic model may be considered appropriate for the vocal-fold tissue when the absolute value of the fluid-solid mass coupling parameter is larger than 10(5) kg/m(3). Otherwise, the poroelastic model may be more accurate. The degree of compressibility of the vocal tissue can also been described by the poroelastic coefficients. Finally, it is revealed that the liquid and solid components in a poroelastic model could have different modal shapes when the coupling between them is weak. The mode decoupling could cause desynchronization and irregular vibration of the folds.

183 血管壁不規則振動の周波数特性表示による動脈硬化および動脈瘤の非侵襲診断(バイオエンジニアリングII,一般講演)

183 血管壁不規則振動の周波数特性表示による動脈硬化および動脈瘤の非侵襲診断(バイオエンジニアリングII,一般講演)

Passive Vibration Reduction with Silicone Springs and Dynamic Absorber

In the precision manufacturing field, the major structural components are often made of rigid and massive elements. Those mechanisms are so fluctuated by swaying of building and resonating of ground floor that the precision gets lower. As a result, quality of products is declined. So far, to minimize the influences of result from external irregular vibration, various technical methods of the absorbing vibration are used. For example, vibration isolation table which use air damper and heavy granite surface plate are used. But, these devices need high cost and low mobility. In this paper, our target is to analyze the external vibration and then to develop a mechanism which is able to reduce the effect. It is also able to be produced at a lower cost. Firstly, a silicone support is proposed as a simple vibration isolating mechanism. Swaying and resonating of a building have 2∼4Hz vibrating frequency when a person is running on a treadmill, similar phenomena happen. Therefore, the supports are mounted under the running pad of a treadmill. This is a passive vibration isolator. The support is designed to have low stiffness and high deformation to isolate and absorb the vibration. As a result, it reduces the peak amplitude of vibration by about 80%. Secondly, a dynamic vibration absorber is developed to minimize the repetitive vibration. The absorber has a fundamental resonating frequency by its spring and mass. The resonating frequency is designed to have close value to the vibrating frequency of the treadmill. The length of beam can be adjusted to have variable resonance according to the external vibration. This absorber also reduces vibration by 84%. The passive vibration isolator and dynamic vibration absorber can be applied to precision equipments with repetitive motion or with disturbance of swaying of building.

Arytenoid Adduction for Correcting Vocal Fold Asymmetry: High-Speed Imaging

We hypothesized that high-speed digital imaging provides a quantitative method to evaluate the effect of arytenoid adduction for the correction of asymmetric and irregular vocal fold vibration in unilateral vocal fold paralysis. Six subjects with unilateral vocal fold paralysis participated in the study (4 male, 2 female; mean [-SD] age, 52.5 +/- 21.3 years). Videokymographic and laryngotopographic methods for image analysis were performed for high-speed recordings of vocal fold vibration for visualizing the glottal vibratory patterns, and for quantifying the frequency of vibration of each vocal fold, respectively. Comparisons of the paralyzed and the normal vocal folds were made before and after arytenoid adduction. Analysis of the laryngotopographs revealed 2 distinct frequencies of vibration for the paralyzed and the contralateral vocal folds for all subjects before surgery. After arytenoid adduction, the vibration frequencies became identical or nearly identical in all subjects. Asymmetric vibration in vocal fold paralysis was exemplified by differences in vibration frequency between the vocal folds. The present data showed that after arytenoid adduction the vibration frequencies and the vibratory patterns of the contralateral vocal folds approached symmetry. This surgical procedure could improve the functional symmetry of the larynx for phonation.

Collagen Injection for Correcting Vocal Fold Asymmetry: High-Speed Imaging

We hypothesized that high-speed digital imaging with videokymographic and laryngotopographic analysis would provide a quantitative method to evaluate the effect of collagen injection for the correction of asymmetric and irregular vocal fold vibration in unilateral vocal fold paralysis. Videokymographic and laryngotopographic analysis was performed for high-speed digital recordings of vocal fold vibration for visualizing the glottal vibratory patterns, and for quantifying the frequency of vibration of each vocal fold, respectively, including comparisons between the paralyzed and normal vocal folds before and after surgery. This included prospective observations of 11 subjects with unilateral vocal fold paralysis (4 male, 7 female; mean +/- SD age, 67.1 +/- 12.0 years) using high-speed digital image analysis before and after collagen injection. Analysis of the laryngotopographs revealed 2 distinct frequencies of vibration for the paralyzed and contralateral vocal folds for 8 of the 11 subjects before surgery. After collagen injection, the vibration frequencies became identical, despite asymmetric vibration amplitudes. Asymmetric vibration amplitudes were also observed in the other 3 subjects before surgery, but the amplitudes became symmetric after collagen injection, despite a persistent phase shift. Asymmetric vibration in vocal fold paralysis was exemplified by differences in vibration frequency and amplitude between the vocal folds. The present study showed that after collagen injection, these aspects of vibratory patterns improved toward symmetry. This surgical procedure could improve the functional symmetry of the larynx for phonation.

Total fixation of cricoarytenoid joint of a patient with rheumatoid arthritis and hashimoto thyroiditis

The incidence of cricoarytenoid joint fixation in case of rheumatoid arthritis is 17 to 33%. In later stages of rheumatoid arthritis, a gradual fixation of cricoarytenoid joint develops and both halves of the larynx become less movable which calls for endotracheal intubation; while total fixation of this joint demands surgical tracheotomy. Hashimoto thyroiditis can display symptoms which are difficult to distinguish from the ones present in total fixation of cricoarytenoid joint caused by rheumatoid arthritis. A 60-year-old woman in terminal stage of rheumatoid arthritis and Hashimoto thyroiditis, diagnosed after clinical and other examinations. She was treated for strident breathing with surgical tracheotomy. The microscopic examination of the larynx with the use of laryngoscopic pincers suggested the immovability of the right and very limited movability of the left arytenoid cartilage. A computerized endovideostroboscopy showed only passive vertical vibrating movements of the right vocal cord and irregular vibrations of the left vocal cord. Total fixation of the cricoarytenoid joint can be caused by many pathological processes, but so far references have shown no case of rheumatoid arthritis and Hashimoto thyroiditis. In differential diagnostics, one of many examinations is the microscopic examination of the larynx, but it is very important to determine the movability of the arytenoid cartilage with the use of appropriate instruments in total endotracheal anaesthesia while the patient is fully relaxed. Movements in cricoarytenoid joints in patients with Hashimoto thyroiditis and the same conditions are preserved.

A scalable micro-power converter for multi-source piezoelectric energy harvesting applications

This paper presents a conversion scheme based on active control for harvesting power from multiple piezoelectric transducers with higher efficiency than traditional passive approaches. The use of multiple sources is often mandatory for boosting up the available output power. The proposed approach guarantees that each source operates efficiently, especially in case of irregular vibrations and heterogeneous transducers. A prototype system was developed and validated in realistic conditions: three 0.5×12.7×31.8 mm3 Q220-A4-303YB transducers from Piezo Systems of different wear conditions loaded with 20g tip masses were stimulated with the vibrations recorded in a train passenger car at 100 km/h. The converter harvested up to 142 μW@0.22g-RMS and up to 90 μW@0.11g-RMS. With the latter vibrations the extra harvested power with respect to a standard passive electronic interface was at least 41%. The converter is modular and the number of sources can be easily increased.

Efficient Energy Harvesting from Irregular Mechanical Vibrations by Active Motion Control

A vibration-driven micropower generator with a high-Q mechanical resonator efficiently works under single-frequency vibration. However, the associated narrow operation frequency bandwidth tightly limits the power output under commonly observed wideband ambient vibrations. In this paper, we present a power-generation scheme in which the motion of an internal mass element is actively controlled. The control is such that the vibrating environment is forced to do the maximum possible work to the power generator. Electret-based energy conversion was analyzed as a means to realize the scheme, drawing on evidence from an experiment. We further analyzed the active control in general terms to reveal potential performance that is substantially above the conventional designs.

이족보행 안전성을 위한 골반기구의 제어시스템 설계

The pelvis platform is the mechanical part which accomplishes the activities of diminishing the disturbances from the lower body and maintaining a balanced posture. When a biped robot walks, a lot of disturbances and irregular vibrations are generated and transmitted to the upper body. As there are some important machines and instruments in the upper body or head such as CPU, controller units, vision system, etc., the upper part should be isolated from disturbances or vibrations to functions properly and finally to improve the biped stability. This platform has 3 rotational degrees of freedom and is able to maintain balanced level by feedback control system. Some sensors are fused for more accurate estimation and the control system which integrates synchronization and active filtering is simulated on the virtual environment.

Nonvibrating segment predicting glottis carcinoma

Endovideolaryngostroboscopy is the obliged evaluation tool in our everyday practice. Standardized protocol in management of broad spectrum of vocal pathology is useful in clinical, scientific and educational evaluation of patient from the first interview till the end of the treatment. Using of contemporary computerised multidimensional analysis of stroboscopic image we are approaching to optimum evaluation of any kind of interpersonal communication disorder. There were 66 patients in prospective clinical study of correlation between suspect endovideolaryngostroboscopic findings and histo-pathology verification of glottis carcinoma. Asymmetric and irregular vibrations with absent mucosal wave or absent vibrations of one part or of the whole vocal fold was improved as carcinoma in 85% of patients. The most frequent diagnosis was Ca planocellularae invasivum G2 NG 2, with subsequent open chordectomy. In every case of hoarseness longer more than 14 days, endovideolaryngostroboscopy is the golden standard for evaluating the need for microlaryngoscopy and biopsy.

Self-Organization of Irregular Nanoelectromechanical Vibrations in Multimode Shuttle Structures

We investigate theoretically multimode electromechanical "shuttle" instabilities in dc voltage-biased nanoelectromechanical single-electron tunneling devices. We show that initially irregular (quasiperiodic) oscillations that occur as a result of the simultaneous self-excitation of several mechanical modes with incommensurable frequencies self-organize into periodic oscillations with a frequency corresponding to the eigenfrequency of one of the unstable modes. This effect demonstrates that a local probe can selectively excite global vibrations of extended objects.

Spatio-temporal quantification of vocal fold vibrations using high-speed videoendoscopy and a biomechanical model

Pathologic changes within the organic constitution of vocal folds or a functional impairment of the larynx may result in disturbed or even irregular vocal fold vibrations. The consequences are perturbations of the acoustic speech signal which are perceived as a hoarse voice. By means of appropriate image processing techniques, the vocal fold dynamics are extracted from digital high-speed videos. This study addresses the approach to obtain a parametric description of the spatio-temporal characteristics of the vocal fold oscillations for the aim of classification. For this purpose a biomechanical vocal fold model is introduced. An automatic optimization procedure is developed for fitting the model dynamics to the observed vocal fold oscillations. Thus, the resulting parameter values represent a specific vibration pattern and serve as an objective quantification measure. Performance and reliability of the optimization procedure are validated with synthetically generated data sets. The high-speed videos of two normal voice subjects and six patients suffering from different voice disorders are processed. The resulting model parameters represent a rough approximation of physiological parameters along the entire vocal folds.

Phonovibrogram Visualization of Entire Vocal Fold Dynamics

High-speed (HS) video recordings are the up-to-date method for visualizing irregular vocal fold vibrations. However, perceptive evaluation during offline replay is time consuming and shows high inter-rater variability. A visualization procedure is presented that extracts vocal fold vibrations from HS videos and transfers the motion information into a set of three phonovibrogram (PVG) images that make visual vocal fold displacements (PVG-0), velocities (PVG-1), and accelerations (PVG-2). The principles of PVG computation as well as their application to three clinical examples (normal voice, laryngeal nerve paralysis, functional voice disorder with vocal nodules) are presented. For normal and dysphonic subjects, the PVG images show the characteristics of vocal fold vibrations as concern the dynamic patterns of displacements, velocities, and accelerations. The PVG approach makes visual the entire range of motion of vibrating vocal fold edges in easy-to-read color images for differentiation of normal and pathologic voices. PVG images are printable and can be stored on a hard-disc drive, enabling the documentation of the course of voice disorders that is essential for evidenced-based medicine. PVG visualization has the potential to overcome the subjective quality of assessing HS videos, which makes it a valuable tool with broad clinical application.

Bifurcations and chaos in register transitions of excised larynx experiments

Experimental data from an excised larynx are analyzed in the light of nonlinear dynamics. The excised larynx provides an experimental framework that enables artificial control and direct observation of the vocal fold vibrations. Of particular interest in this experiment is the coexistence of two distinct vibration patterns, which closely resemble chest and falsetto registers of the human voice. Abrupt transitions between the two registers are typically accompanied by irregular vibrations. Two approaches are presented for the modeling of the excised larynx experiment; one is the nonlinear predictive modeling of the experimental time series and the other is the biomechanical modeling (three-mass model) that takes into account basic mechanisms of the vocal fold vibrations. The two approaches show that the chest and falsetto vibrations correspond to two coexisting limit cycles, which jump to each other with a change in the bifurcation parameter. Irregular vibrations observed at the register jumps are due to chaos that exists near the two limit cycles. This provides an alternative mechanism to generate chaotic vibrations in excised larynx experiment, which is different from the conventionally known mechanisms such as strong asymmetry between the left and right vocal folds or excessively high subglottal pressure.

Quantifying the complexity of excised larynx vibrations from high-speed imaging using spatiotemporal and nonlinear dynamic analyses

In this paper, we investigate the biomechanical applications of spatiotemporal analysis and nonlinear dynamic analysis to quantitatively describe regular and irregular vibrations of twelve excised larynges from high-speed image recordings. Regular vibrations show simple spatial symmetry, temporal periodicity, and discrete frequency spectra, while irregular vibrations show complex spatiotemporal plots, aperiodic time series, and broadband spectra. Furthermore, the global entropy and correlation length from spatiotemporal analysis and the correlation dimension from nonlinear dynamic analysis reveal a statistical difference between regular and irregular vibrations. In comparison with regular vibrations, the global entropy and correlation dimension of irregular vibrations are statistically higher, while the correlation length is significantly lower. These findings show that spatiotemporal analysis and nonlinear dynamic analysis are capable of describing the complex dynamics of vocal fold vibrations from high-speed imaging and may potentially be helpful for understanding disordered behaviors in biomedical laryngeal systems.