Periodicity Of Vibration Research Articles

Enhancement Thermoelectric Properties of Cux-doped Nanostructure Bi-Sb-Te Thermoelectric Materials by Spark Plasma Sintering

Nanostructure Cux-doped Bi0.5Sb1.5-xTe3 thermoelectric materials was successfully prepared by Mechanical alloys and spark plasma sintering. In the reasearch, the crystallinity, particle size, and chemical composition were characterized by XRD, EDS, respectively. Thermoelectric properties with a maximum ZT value up to 1.17 has been obtained at 407 K in prepared Cu0.04-doped Bi0.5Sb1.496Te3 sample. The achieved higher ZT value is attributed that Cu as doping at the Sb sites introduced additional holes to enhance carrier mobility and Cu dopants interrupted the periodicity of lattice vibration to decrease lattice thermal conductivity. It is suggested that the as-prepared nanostructure Cux-doped Bi0.5Sb1.5-xTe3 thermoelectric materials has high potential for thermoelectric energy conversion application.

A self-powered vibration sensing element based on three-dimensional graphene field effect transistor

Piezoelectricity of two-dimensional layered materials is of great significance for electromechanical coupling applications in nanoelectromechanical systems. The nanoscale devices based on graphene have attracted intense interest due to its excellent electronic and mechanical properties. However, the centrosymmetric crystal structure in intrinsic graphene severely restricts its applications in mechanical sensors, transducers, and energy harvesters. In this paper, a self-powered vibration sensing element based on rolled-up single-layer graphene is proposed and demonstrated, which realizes the conversion from mechanical vibrations into electrical signals. In contrast to previous pioneering works requiring silica cavities or Si/SiO2 calibration grating substrate to support the graphene, a three-dimensional (3D) non-closed tubular structure is adopted to develop the piezoelectricity in single-layer graphene, where the inversion symmetry of single-layer graphene is broken via self-rolled-up process induced strain. Hence, apparent piezoresponse from the 3D non-closed tubular graphene field effect transistor is observed. Moreover, a peak-to-peak amplitude for the piezoelectric current up to 4.2 is achieved, corresponding to the periodicity of mechanical vibration, and the value can increase to 10.8 nA by applying a small source–drain voltage of 6 mV. The device is also sensitive to mechanical vibration with different frequencies and shows similar currents. The electromechanical coupling in rolled-up graphene provides a basis for the applications in sensing, actuating, and energy harvesting.

Presbyphonia as an Individual Process of Voice Change

ObjectiveThe aim of the study was to determine the individual variability of the severity of dysphonia in the population of older women and men using the initial perceptual voice assessment (GRBAS) and objective diagnosis of the clinical form of Presbyphonia with laryngeal visualization technique (High-Speed Digital Imaging [HSDI]) and acoustic voice analysis (Diagnoscope Specjalista). MethodsThe study included 302 elderly women and men. Application of perceptual GRBAS scale allowed to extract 230 subjects with voice disorders (Group I). Remaining 72 elderly subjects without the symptoms of dysphonia consisted Group II. Group III included 50 subjects with euphonic voice. In the assessment of dysphonia, visualization technique (HSDI) as well as acoustic method (Diagnoscope Specjalista). The observation of real vibration of vocal folds using HSDI technique and HS camera allowed to examine symmetricity (Shaw-Deliyski scale), periodicity and amplitude of vibration, Mucosal Wave (MW) morphology, Glottal Closure Type, and value of Open Quotient (OQ). Acoustic analysis allowed to assess value of Fundamental Frequency (F0), Maximum Phonation Time (MPT) as well as Jitter, Shimmer, Noise-to-Harmonics Ratio (NHR) parameters. Narrowband Spectrography was performed. ResultsHSDI technique allowed to register in elderly women with voice disorders a mild asymmetry and aperiodicity of vibrations, MW reduction, amplitude increase and glottal insufficiency in the posterior segment of glottis which indicated edematous changes in the larynx. In 90% of men in this group, moderate asymmetry and aperiodicity were observed as well as amplitude decrease, significant limitation of MW and glottal insufficiency in the middle segment of the glottis which indicated atrophic changes in the larynx. In remaining 10% of men, amplitude of vibration was increased which indicated the existence of hypofunctional dysphonia. Objective confirmation of glottal insufficiency in women with edematous changes was high value of OQ in posterior segment of the glottis registered with HSDI technique. In men with larynx atrophy, the value of OQ was the highest in the middle segment of the glottis. Glottal insufficiency, especially in the middle segment, coexisted with the increase of NHR parameter observed in acoustic examination and with numerous nonharmonic components in the scope of high frequencies revealed in narrowband spectrography, especially in men with larynx atrophy. What is more, in men, the increase of F0 and reduction of MPT was registered. In women with edematous changes of the larynx, acoustic analysis revealed decrease of F0 value, increase of Jitter, Shimmer, NHR as well as reduction of MPT. Narrowband sopectrography revealed not only harmonic components but also nonharmonics in the range of low, medium, and high frequencies. ConclusionsThe course of Presbyphonia varies individually in the elderly. In many subjects, the process of aging does not influence the quality of voice. Crucial importance in the diagnosis of Presbyphonia is assigned to High-Speed Digital Imaging technique which confirms the existence of edematous changes in the larynx in women as well as atrophy and hypofunctional dysphonia in men. The acoustic examination of voice confirmed the individual variability of the severity of Presbyphonia in the elderly depending on the clinical form of dysphonia determined by the gender of the diagnosed person.

Modeling of humidity effect on electromechanical properties of viscoelastic dielectric elastomer

As is known, the ambient environment, such as temperature and humidity, may affect the electromechanical properties of dielectric elastomer (DE). In this research, we carry out an analysis to explore the humidity effect on electromechanical performance of a viscoelastic DE, by prescribing the shear moduli, the viscous damping, and the relative dielectric constant of the DE are humidity-dependent values. The dependency relationships between these parameters and the relative humidity are obtained by fitting the presupposed models to experimental data. The humidity effect on static and dynamic electromechanical performances is explored by exhibiting the creeping deformation of both elastic and non-elastic stretch of the viscoelastic DE. Phase paths and Poincaré maps are utilized to detect the humidity effect on the stability and periodicity of the nonlinear vibration. Finally, the variation tendency of resonant frequency of the viscoelastic DE system is investigated by continuously varying the relative humidity.

Voltage-induced beating vibration of a dielectric elastomer membrane

An AC voltage induces a nonlinear vibration of dielectric elastomers (DEs), which enables DE to be served as soft dynamical devices and robots. As is known, a special beating vibration may occur during the nonlinear oscillation of DEs, leading to the undesired electromechanical failures and instabilities. In this article, a numerical study is developed to explore the beating vibration of DEs with establishment of the dynamics model. The effects of geometric sizes, limiting stretch, as well as amplitude and frequency of applied voltage on the beating vibration performance of DEs are investigated, respectively. The corresponding range of actuation and materials parameters that determines the occurrence of beating vibration is obtained. The phase paths and Poincare maps are employed to detect the stability and periodicity of nonlinear beating vibration of DEs. The bifurcation analyses of dynamic electromechanical performances of DE are also investigated.

Roles of Cu in the Enhanced Thermoelectric Properties in Bi0.5Sb1.5Te₃.

Recently, Cu-containing p-type Bi0.5Sb1.5Te3 materials have shown high thermoelectric performances and promising prospects for practical application in low-grade waste heat recovery. However, the position of Cu in Bi0.5Sb1.5Te3 is controversial, and the roles of Cu in the enhancement of thermoelectric performance are still not clear. In this study, via defects analysis and stability test, the possibility of Cu intercalation in p-type Bi0.5Sb1.5Te3 materials has been excluded, and the position of Cu is identified as doping at the Sb sites. Additionally, the effects of Cu dopants on the electrical and thermal transport properties have been systematically investigated. Besides introducing additional holes, Cu dopants can also significantly enhance the carrier mobility by decreasing the Debye screen length and weakening the interaction between carriers and phonons. Meanwhile, the Cu dopants interrupt the periodicity of lattice vibration and bring stronger anharmonicity, leading to extremely low lattice thermal conductivity. Combining the suppression on the intrinsic excitation, a high thermoelectric performance—with a maximum thermoelectric figure of merit of around 1.4 at 430 K—has been achieved in Cu0.005Bi0.5Sb1.495Te3, which is 70% higher than the Bi0.5Sb1.5Te3 matrix.

Impact of Cricothyroid Muscle Contraction on Vocal Fold Vibration: Experimental Study with High-Speed Videoendoscopy

The aim of this study was to evaluate the effects of cricothyroid muscle contraction on vocal fold vibration, as evaluated with high-speed videoendoscopy, and to identify one or more aspects of vocal fold vibration that could be used as an irrefutable indicator of unilateral cricothyroid muscle paralysis. This was an experimental study employing excised human larynges. Twenty freshly excised human larynges were evaluated during artificially produced vibration. Each larynx was assessed in three situations: bilateral cricothyroid muscle contraction, unilateral cricothyroid muscle contraction, and no contraction of either cricothyroid muscle. The following parameters were evaluated by high-speed videoendoscopy: fundamental frequency, periodicity, amplitude of vocal fold vibration, and phase symmetry between the vocal folds. Although neither unilateral nor bilateral cricothyroid muscle contraction altered the periodicity of vibration or the occurrence of phase asymmetry, there was a significant decrease in fundamental frequency in parallel with decreasing longitudinal tension. We also found an increase in vibration amplitude of right and left vocal folds, which were similar in terms of their behavior for this parameter in the various situations studied. Our results suggest that differences in vibration amplitude and phase symmetry between vocal folds are not reliable indicators of unilateral cricothyroid muscle paralysis.

Could Neuromuscular Electrical Stimulation Really Lead to Changes in Voice of Swallowing Disorder Caused by a Stroke?

This study investigated the effect of Neuromuscular Electrical Stimulation (NMES) on the loudness, pitch and quality of the voice of the males diagnosed with dysphagia by stroke. NMES was conducted on experimental group of 15 patients for 2 months repeatedly while compensatory strategies for dysphagia were performed on control group of 15 patients. Loudness, pitch (F₀) and quality (Jitter, Shimmer, NNE; Normalized Noise Energy) of the voice was measured by using acoustic-phonetic analysis. For statistical test, difference in voice change after the treatments was compared by using analysis of covariance (ANCOVA). As the result of analysis, NMES and compensatory strategies had significant difference in intensity, jitter and shimmer (p<.05) while they did not in pitch and NNE. After the intervention of NMES, voice loudness of the subjects was enhanced and periodicity of vocal cord vibration (Jitter, Shimmer) was stabilized. The results of this study imply that NMES may have effect on enhancement of voice loudness and stabilization of periodicity of vocal cord vibration.

Measuring airborne components of seismic body vibrations in a Middle-Asian sand-dwelling Insectivora species, the piebald shrew (Diplomesodon pulchellum)

Self-produced seismic vibrations have been found for some subterranean rodents but have not been reported for any Insectivora species, although seismic sensitivity has been confirmed for blind sand-dwelling chrysochlorid golden moles. Studying the vocal behaviour of captive piebald shrews, Diplomesodon pulchellum, we documented vibrations, apparently generated by the whole-body wall muscles, from 11 (5 male, 6 female) of 19 animals, placed singly on a drum membrane. The airborne waves of the vibratory drumming were digitally recorded and then analysed spectrographically. The mean frequency of vibration was 160.5 Hz. This frequency matched the periodicity of the deep sinusoidal frequency modulation (159.4 Hz) found in loud screech calls of the same subjects. The body vibration was not related to thermoregulation, hunger-related depletion of energy resources or fear, as it was produced by well-fed, calm animals, at warm ambient temperatures. We hypothesize that in the solitary, nocturnal, digging desert piebald shrew, body vibrations may be used for seismic exploration of substrate density, to avoid energy-costly digging of packed sand for burrowing and foraging. At the same time, the piercing quality of screech calls due to the deep sinusoidal frequency modulation, matching the periodicity of body vibration, may be important for agonistic communication in this species.

Chondrocytes suspended in modified fibrin glue for vocal fold augmentation: An in vitro study in a porcine larynx model

Injection laryngoplasty is an option for treatment of dysphonia following vocal fold paralysis. Modified fibrin glue with suspended chondrocytes might be a favorable cell-based material for permanent vocal fold medialization. We compared fibrin glue with suspended chondrocytes to collagen and hyaluronic acid gels concerning alteration of vocal fold vibration and correct intralaryngeal placement after intralaryngeal injection into porcine larynges. Viscoelastic properties of the materials were analyzed by means of a parallel plate rheometer. Fibrin glue with cells was comparable to collagen and hyaluronic acid with respect to amplitudes, symmetry, and periodicity of vocal fold vibration. Application and positioning of fibrin glue with suspended chondrocytes were technically undemanding and comparable with controls. Complex stress modulus of fibrin glue with suspended cells was comparable to that of collagen gel. Fibrin glue with suspended chondrocytes seems suitable for the indication of injection laryngoplasty and holds promise for permanent vocal fold medialization.

Voice production mechanisms following phonosurgical treatment of early glottic cancer.

Although near-normal conversational voices can be achieved with the phonosurgical management of early glottic cancer, there are still acoustic and aerodynamic deficits in vocal function that must be better understood to help further optimize phonosurgical interventions. Stroboscopic assessment is inadequate for this purpose. A newly developed color high-speed videoendoscopy (HSV) system that included time-synchronized recordings of the acoustic signal was used to perform a detailed examination of voice production mechanisms in 14 subjects. Digital image processing techniques were used to quantify glottal phonatory function and to delineate relationships between vocal fold vibratory properties and acoustic perturbation measures. The results for multiple measurements of vibratory asymmetry showed that 31% to 62% of subjects displayed higher-than-normal average values, whereas the mean values for glottal closure duration (open quotient) and periodicity of vibration fell within normal limits. The average HSV-based measures did not correlate significantly with the acoustic perturbation measures, but moderate correlations were exhibited between the acoustic measures and the SDs of the HSV-based parameters. The use of simultaneous, time-synchronized HSV and acoustic recordings can provide new insights into postoperative voice production mechanisms that cannot be obtained with stroboscopic assessment.

High-Speed Laryngeal Imaging Compared With Videostroboscopy in Healthy Subjects

To describe normal vocal fold vibratory characteristics recorded with high-speed digital imaging (HSV) of the larynx. Prospective study of healthy subjects who volunteered to undergo laryngeal HSV and videostroboscopy. Image analysis was randomly assigned to 3 blinded raters. Community-based clinic with a specialty in laryngology. Fifty healthy subjects aged 21 to 65 years who were nonsmokers and who had no voice problems, laryngopharyngeal reflux, or reactive airway disease. The following characteristics of vibration were described: glottal configuration, phase closure, vibratory symmetry, mucosal wave propagation, amplitude of vibration, and periodicity of vibration. Interrater and intrarater reliabilities were calculated for both imaging modalities. The range of findings for each measure is described. The comparison of videostroboscopy ratings with ratings from HSV studies did not reveal any significant difference between the 2 modalities for any of the measures except for the assessment of periodicity. Aperiodic vibratory characteristics were noted on 30% of the videostroboscopy studies (n = 15) and in only 4% of the HSV studies (n = 2) (P <. 001). Although interrater and intrarater agreement were considered to be generally acceptable, a significant rater effect was identified. This preliminary study describes a range of normal values for vocal fold vibratory characteristics as recorded with laryngeal HSV, providing a basis for comparison of studies in patients with voice problems.

Harmonics-to-Noise Ratio: An Index of Vocal Aging

Distinguishing between vocal changes that occur with normal aging and those that are associated with disease is an important goal of research in voice. Several acoustic measures have been used in an attempt to illuminate the integrity of the vocal mechanism, including harmonics-to-noise ratio (HNR), jitter, and fundamental frequency (F 0). HNR is a measure that quantifies the amount of additive noise in the voice signal; jitter reflects the periodicity of vocal fold vibration. In this study, measures of HNR, jitter and F 0 were used to compare vocal function in three groups of normally speaking women: young adults, middle-aged adults, and elderly adults. Significant differences in HNR emerged between the elderly women and the other two groups. F 0 differences were also apparent between the elderly group and the two younger groups; there were no significant differences in jitter between the three groups. HNR was found to be a more sensitive index of vocal function than jitter. The significant lowering of HNR evident in the elderly speakers may be attributable in part to medications taken by the majority of these elderly subjects.

Vibratory Characteristics of Teflon-Injected and Noninjected Paralyzed Vocal Folds

This study compared the vibratory characteristics of normal vocal folds, Teflon-injected paralyzed vocal folds, and noninjected paralyzed vocal folds. Laryngeal videostroboscopy under eight phonatory conditions showed that the Teflon-injected vocal folds were adynamic. The noninjected vocal folds, however, vibrated during each of the phonatory conditions although not necessarily like a normal vocal fold. In terms of vocal fold physiology, it appeared that the noninjected paralyzed vocal folds were too compliant, whereas the Teflon-injected vocal folds were too stiff. Because vocal fold paralysis is often treated in voice therapy with "digital manipulation" and "head turning," the effect of these techniques on vocal fold vibration was also studied. The results showed that digital manipulation was superior to head turning for improving glottal closure but that neither technique appeared to influence the periodicity, amplitude, or extent of vocal fold vibration for either the injected or noninjected vocal folds.

食道音声の客観的評価法 母音の音質を対象として

A method of objectively evaluating the voice quality of esophageal speech is described in this paper. We used the vowel/a/ of 27 esophageal speakers as a voice sample.As judged from perceptual impressions, the voice samples were ranked by the paired comparison method. Acoustic parameters such as maximum phonation time, fluctuation of intensity and periodicity of vibration were examined. We compared the perceptual ranking and those three parameters by non-parametric statistical methods. There was a significant correlation between the last two parameters and the perceptual ranking. Low fluctuation (less than 10dB in 500msec from the voice on set) and periodic vibration were assumed to be a standard for the good voice quality of esophageal speech.

An experimental study on the transient response of a stepped canti-lever beam subjected to impact load.

When a stepped beam is impacted, time histories of bending strain are measured by strain gauges which are cemented at the fixed end and the corner of discontinuity in the beam. Although the variations of bending strain calculated by the finite element method based on Bernoulli-Euler beam theory also involve the high frequency modes, those by experiment consist of the basic frequency mode and a few low frequency modes. Since the fixed end of a canti-lever beam in an experiment is not perfectly rigid, the periodicity of vibration is affected by it. The time histories of bending strain on the shelf of discontinuity differ from the flexural motion by the simpler Bernoulli-Euler theory. However, observing the variations of bending strain at the other location, except for the high frequency modes, the vibration of both is in fair agreement.