Maximum Fundamental Frequency Research Articles

Application of von-Karman model for laminated composite singly curved shells with non-uniform boundary conditions

The industrial applications of singly curved shells significantly increased in modern engineering structures and several of those have non-uniform boundary conditions. A detailed relative performance study for the non-uniformly restricted shells can popularize their use further among practicing engineers. The literature review confirms that there is dearth of research studies in this area. This paper aims to fill up that void. A finite element code of C0 continuity combining von-Karman strains, first order shear deformation theory and eight noded curved elements is proposed. Wide variety of shell problems are solved for different boundary conditions, laminations, radii of curvatures, thickness, and plan dimensions. Relative nondimensional deflections and fundamental frequencies are studied for varying boundaries. It is concluded that although the performances of shells are comparable for different boundaries, the shells with CCCC edges offer better performances. These shells should have longer span along the arch direction, a symmetric 16°/-16°/-16°/16° laminate, side/thickness = 100, and radius of curvature/plan = 0.75 to achieve minimum deflection and maximum fundamental frequency.

Approximate closed-form solutions for free vibration of circular arches with discrete lateral braces

Discrete lateral braces are commonly employed to enhance the out-of-plane stability of arches. However, these braces generate coupling effects among vibration modes, which significantly impact the vibration characteristics of the arches. This paper presents an analytical solution for the free vibration analysis of two-hinged arches with equally-spaced lateral translational and/or rotational braces. A simplified method of evaluating the fundamental frequency for the out-of-plane vibration of arches with equally-spaced lateral braces is introduced. The method relies on the conventional approach of representing arch braces through elastic springs, but here the out-of-plane deflection of the braced arch is constructed by adding related coupled sinusoidal functions to that of the unbraced arch, satisfying both the boundary and kinematic conditions. Subsequently, the fundamental frequency and threshold bracing stiffness or stiffness requirement are derived using the Rayleigh–Ritz method. Finite element analysis (FEA) is applied to investigate the flexural-torsional vibration mode and fundamental frequency of arches with discrete braces, and the results from FEA closely match the theoretical predictions. The effects of number of lateral translational and/or rotational brace, out-of-plane slenderness, included angle, bracing stiffness and bracing position on the fundamental frequency are comprehensively analyzed. It is found that when the fundamental frequency of the braced arch increases due to changes in bracing stiffness, the mode shape displays more intricate behavior, rather than following a straightforward low-to-high mode growth pattern. Furthermore, it is observed that in some cases, the addition of rotational bracing stiffness can markedly enhance the maximum fundamental frequency of the arch with both translational and rotational braces.

Vocal Range Variations Elicited With a Standard Mandarin Reading Passage in Individuals With Voice Disorders.

This study examined whether the "Three Bears Passage" (TB), a standard Mandarin reading passage, could elicit significant vocal range variations in individuals with voice disorders. Relative sensitivity of TB versus another existing standard reading passage, "Passage in Mandarin" (PM), for differentiating between individuals with and without voice disorders was also evaluated. Forty-two individuals with normal voice and 30 individuals with voice disorders participated in the study. Maximum fundamental frequency (f0), minimum f0, mean f0, f0 range, maximum vocal intensity, minimum intensity, mean intensity, and intensity range of all participants reading aloud the two passages were measured with Praat to construct speech range profiles (SRPs). Significantly larger vocal range was found for TB than for PM in individuals with voice disorders, including significantly higher maximum f0, mean f0, maximum intensity, mean intensity, and significantly larger f0 range and intensity range. Significantly more limited vocal range was observed in individuals with voice disorders than those without, with more obviously restricted SRPs while reading aloud TB compared to PM. Receiver operating characteristic analysis suggested that TB was more sensitive than PM in distinguishing between individuals with and without voice disorders. Our findings supported the potential of TB as a standard clinical assessment tool for evaluating pathological changes in vocal range. Future studies should explore if therapeutic approaches based on the passage or variations of it could be developed for overcoming functional limitations and restrictions in vocal range for specific voice disorders.

The Long Term Results of Hyaluronic Acid/Dextranomer Injection Laryngoplasty in Unilateral Vocal Fold Paralysis.

This study was conducted to present the long-term functional outcomes of injection laryngoplasty (IL) with hyaluronic acid/dextranomer (HA/D) in unilateral vocal fold paralysis (UVFP). A total of 40 patients who underwent HA/D injection for UVFP were enrolled. The acoustic analysis of the voice was evaluated with jitter percentage, shimmer percentage, maximum phonation time, harmonics-to-noise ratio, and fundamental frequency. The psychosocial effect of the voice was determined using the Voice Handicap Index-10. Fiberoptic endoscopic evaluation of swallowing was performed and 2 scales were used for quantification: a modified penetration-aspiration scale and a dysphagia score. All measurements were performed at preoperative day and postoperative months 1, 6, and 24. A statistically significant improvement was observed for all of the evaluated parameters except the maximum phonation time for postoperative months 1, 6, and 24 (P < .05). In the evaluation of the maximum phonation time, although there was a significant improvement for the postoperative months 1 and 6, no significant difference was observed between the postoperative 24th month and the preoperative value. HA/D injection laryngoplasty is an effective method both in the short- and long-term to improve voice and swallowing functions in patients with UVFP.

Early Assessment of Voice Problems in Post-Thyroidectomy Syndrome Using Cepstral Analysis.

Post-thyroidectomy syndrome (PTS), characterized by voice issues after thyroidectomy without recurrent laryngeal nerve injury, was investigated in this study. The Voice Fatigue Index (VFI) and cepstral analysis were employed for subjective and objective voice evaluation. Retrospective analysis involved 96 patients (37 males, 59 females) who underwent thyroidectomy without nerve injury from April 2018 to June 2022. Assessments pre- and post-thyroidectomy included the Voice Handicap Index (VHI) and VFI, along with auditory perceptual, acoustic (including cepstral), aerodynamic, and glottal vibration analyses. In females, although the GRBAS scale showed no significant change, both VHI and VFI increased post-thyroidectomy. Significant correlations were observed between the VHI and VFI in females. Acoustic analysis indicated a decrease in the cepstral peak prominence (CPP) of vowels (/a/) and sentences in females, with significant correlations between changes in the CPP/a/ and VHI/VFI. The maximum fundamental frequency (F0max) exhibited a significant decrease, correlating with the VHI and VFI changes. The VFI demonstrated effectiveness in subjective PTS voice evaluation, comparable to the VHI. The present study highlights the potential of cepstral analysis as an index reflecting subjective voice discomfort, suggesting its promise for a comprehensive PTS voice evaluation.

The boundary-induced modulation of obstruents and tones in Thai

Limited studies have suggested that tones can be strengthened in domain-initial positions, suggesting that domain-initial strengthening (DIS) effects in a tone language extend beyond the first segment of a prosodic domain. However, these studies have yielded unclear results. This study investigated whether DIS causes boundary-induced changes in tones. This study analyzed the maximum fundamental frequency (f0) of the falling, mid, and low tones in Thai along with acoustic measures of consonants, including the Voice Onset Times (VOTs) of /b/, /p/, and /pʰ/, frication duration of /f/, and consonant-induced f0 perturbation effects associated with these four consonants in domain-initial and domain-medial positions. Some evidence of DIS effects on tones was found, suggesting that DIS effects in a tone language can extend to tone production realized with the vowel that is beyond the first segment. Additionally, the VOTs of /b/, /p/, and /pʰ/ were more negative, unchanged, and longer, respectively, the frication of /f/ was longer, and f0 following /pʰ/ was raised in a domain-initial position compared to a domain-medial position. The findings contribute to the current understanding of the prosody-phonetics interface, particularly with respect to the relationship between DIS and the realization of tones.

Vocal Dose and Vocal Demands in Contemporary Musical Theatre.

To document and quantify vocal dose and student-singers' self-assessment during rehearsals for a contemporary musical theater production. Six student singers fastened the sensor from the KayPentax APM 3200 dosimeter to the lower neck to capture neck vibration data during their preparation for the musical Wonderland by Frank Wildhorn. Data were collected during 8-hour periods, at four different stages throughout the rehearsal process: beginning (music and choreography learning phase), middle (staging phase), and end (running the entire show/dress rehearsal phase), plus a post-production day once the production had concluded to establish a baseline vocal load. Students concurrently completed the EASE questionnaire1 after each data collection day. The EASE score (Appendix1) and demographics/perceptual questionnaire (Appendix2) revealed that all subjects (three males and three females) found the singing role vocally and physically demanding but only two found the roles to be emotionally challenging. The musical score demanded a higher usage of chest register (judged perceptually) than mixed register from lead singers. All subjects' maximum fundamental frequency range exceeded the pitch range required by the score. The mean daily vibration dose (distance dose, as computed with Kay Pentax Software) of the three individual female singers' during rehearsals, 5,203 meters, was higher than the mean daily dose of the three male singers, 3,766 meters. The subjects' self-ratings on the EASE were not correlated with the distance dose. A review of Wonderland's score and perceptual judgment of the singers' performances revealed extensive use of chest register, with belting and mix vocal strategies being the predominant stylistic choices. Students described the singing roles' vocal and physical requirements as more challenging than the character's emotional components. This pilot study provides information on the vocal dose for lead and ensemble singers in rehearsal for a Contemporary Musical Theatre production. Singers and voice professionals may find dosimetry a valuable tool for monitoring the vocal dose during rehearsals and performances.

Meows of captive feral domestic cats (Felis silvestris catus) in the mating season: acoustic correlates of caller identity and sex

Abstract This study investigates the frequency, temporal and power parameters in 11 (5 males, 6 females) captive feral domestic cats Felis silvestris catus, vocalising in their individual outdoor enclosures during the mating season. Discriminant function analysis (DFA) classified the meows to correct callers with 79.2% accuracy, which exceeded the chance level of 22.9 ± 2.8%, calculated with permutation test. Male meows were lower-frequency, with the maximum fundamental frequency of 0.37 ± 0.05 kHz vs 0.61 ± 0.16 kHz in females. Sex differences in the maximum, beginning and end fundamental frequencies varied from 32 to 39%, depending on acoustic parameter. The DFA classified the meows to correct sex with accuracy of 88.0%, which exceeded the chance level of 58.2 ± 3.1%. We discuss that the meows encode information about individual identity and sex and that acoustic differences in frequency parameters of the meows exceed sexual dimorphism of body size in domestic cat.

Acoustic features of long‐distance calls of wild cheetahs (Acinonyx jubatus) are linked to the caller age from newborns to adults

AbstractWild cheetahs Acinonyx jubatus of all age classes, from newborns to adults, use their long‐distance chirps for communication with conspecifics. We investigated the ontogenetic changes of eight acoustic parameters of the chirps produced by wild‐living cheetahs across 14 age classes in Kenya. Chirp maximum fundamental frequency (f0max) was found to be best acoustic correlate of cheetah age. The f0max was the highest in neonates (up to 10 kHz), then decreased steadily across age classes and reached a plateau of about 1 kHz in mature adults older than 4 years. Based on a close relationship of f0max with age, we fitted polynomial models for estimating cheetah age by their chirps. We discuss that gradual changes of chirp f0max suggest the gradual development of cheetah vocal apparatus. Model for age estimation by chirps in the cheetah proposed in this study may provide conservationists a non‐invasive bioacoustic tool for estimating cheetah age, particularly at ages younger than 4 years. However, introducing more data from cheetahs of precisely known age would be necessary for obtaining more accurate results of age determination by voice for the older individuals.

Linear and Nonlinear Free Vibration and Optimal Design of Bio-Inspired Helicoidal CFRPC Laminated Plates

Bio-inspired helicoidal carbon fiber reinforced polymer composite (CFRPC) laminates stacked with Bouligand configurations are considered to own great potential in engineering fields. The optimization design of helicoidal layups with single-form and combination-form of linear and nonlinear helicoidal arrangements is carried out using ABAQUS and Isight. Two single-objective optimizations and one multi-objective optimization of maximum fundamental frequency and the difference among the first four adjacent vibration frequencies of helicoidal CFRPC laminated plates are performed and the nonlinear free vibration characteristics of optimal ones are investigated for the first time. Numerical studies are carried out for 16-ply symmetrical rectangular helicoidal laminated plates under two different boundary conditions compared with quasi-isotropic counterparts. The results show that the combination-form helicoidal layup sequences can improve the linear vibration characteristics of CFRPC laminated plates. The plates stacked with the combination form of nonlinear Fibonacci and linear patterns are expected to provide better vibration characteristics.

Vocal Outcomes Following Laser-Assisted Sulcus Release for Superficial and Deep Vocal Fold Sulcus

The objective is to study vocal outcomes following laser-assisted sulcus release (LASR), having documented the length and depth of the sulcus intraoperatively. LASR performed for superficial and deep sulci were included. Retrospective, observational. The preoperative and 3-month postoperative and post voice-therapy Voice Handicap Index 10 (VHI), Grade-Roughness-Breathiness-Asthenia-Strain of the voice (GRBAS), Maximum Phonation Time (MPT), Fundamental Frequency (FO), and stroboscopy findings were noted retrospectively from our voice clinic records of LASR patients. Intraoperative sulci length and depth details were noted from records. Patients with coexisting lesions, surgically tackled, were excluded. In a total of 14 patients, 21 superficial sulci and eight deep sulci were operated by LASR. The average preoperative VHI improved from 25.3 to 9.9, GRBAS from 10.6 to 3.5, and MPT from 7.6 to 12.3seconds. The preoperative average FO was 235.9Hz in 12 patients (no pick-up in two) with a postoperative 248.4Hz. Using the Mann-Whitney U test, we found a statistically significant improvement in MPT, VHI, and GRBAS of the patients. There was no significant improvement in the FO of the patients. There was no postoperative voice deterioration in any patient. A preoperative phonatory gap was found in all patients, which postoperatively was absent in 10, markedly decreased in three, present in one with stroboscopy revealing an improvement in mucosal wave amplitude in 13 patients. In four patients with deep bilateral sulci where the LASR had been ligament deep, VHI improved from 26 to 13.3, GRBAS from 12 to 6.5, and MPT from 4.3 to 9.5seconds. Using the Mann-Whitney U test, all three parameters were significantly improved. A statistically significant vocal improvement in VHI, GRBAS, and MPT was observed at 3months, in superficial and deep sulci, operated by LASR. LASR is a simple, quick, and easily replicable surgery. Larger multi-centric studies with long-term follow-up are recommended.

Optimization of graphene/fibre reinforced cantilever skew laminates for maximum fundamental frequency via non-uniform distribution of reinforcements

Three-phase graphene/fibre-reinforced cantilever skew laminates are optimized with the design objective of maximizing the fundamental frequency. Four optimal design problems are formulated involving one, two, three, and four design variables: graphene content, fibre content, layer thicknesses, and the fibre orientations. Optimization is implemented using a Sequential Quadratic Programming optimization algorithm within finite element analysis. It is observed that optimizing the graphene and fibre contents across the thickness leads to increased fundamental frequency. A trend is observed for the frequency of skew laminates to increase but for their design efficiency to decrease compared to rectangular laminates.

Maximisation of Bending and Membrane Frequencies of Vibration of Variable Stiffness Composite Laminated Plates by a Genetic Algorithm

PurposeIn comparison to traditional, constant stiffness laminates, variable stiffness composite laminates (VSCL) with curvilinear fibres represent an extra analysis effort. It is the purpose of this work to present and test a relatively simple optimisation procedure, in order to find the maximum fundamental frequency of vibration in bending and in in-plane vibrations. It is also intended to explain why certain fibre paths lead to higher frequencies.MethodsThe optimisation is performed using a genetic algorithm (GA), which is described in detail. The bending and the in-plane plate models are based on the p-version Finite Element Method. Each model requires a small number of degrees of freedom, an important feature because applying the GA involves the solution of a large number of eigenvalue problems. In order to support the physical interpretation of the optimal designs, mode shapes and stress fields corresponding to some optimal solutions are illustrated.ResultsSingle- and multi-layer plates with different boundary conditions and fibre path types are studied. Fibre paths that lead to maximum fundamental frequencies are found and justified. The consequences that maximising the first frequency has on the higher-order modes of vibration are studied.ConclusionThe proposed optimisation and modelling methods are effective. Curvilinear fibres with the characteristics considered led to the maximum first natural frequency of vibration in a few cases, but not all. Particularly in in-plane vibrations, curvilinear fibres can provide major gains in comparison to straight fibres. The increase in the vibration frequency is accompanied by, overall, larger stresses.

Influence of GNP nanoparticles on shear and dynamic behaviour of flat-joggle-flat composite joints

The focus of the current research is to examine the effects of adding graphene nanoparticles (GNP) to GFRP flat-joggle-flat (FJF) composite joints made with the co-cure manufacturing process on their mechanical and vibrational properties. The experimental results show that adding 0.25, 0.50, and 0.75 wt% GNP reinforcement to the resin greatly improved the strength properties of composite joints by 8.30%, 26.37%, and 34.73%, respectively. However, a higher percentage of GNPs (1%) reduced the strength of joints by 3.90% due to agglomeration. Field emission scanning electron microscopy (FESEM) reveals that 0.75 wt% of GNP reinforced enhanced interfacial interaction and created coarser interfaces in the bond line to postpone failure. Cutting-edge internal failure and damage progression modes are incorporated by the ultrasonic C-scan method. The modal analysis confirmed that the 0.75 wt% GNP reinforcement had the maximum fundamental natural frequency of 918.1 Hz compared to other weight percentages. The obtained experimental results and used methods are in good agreement.

Multi-objective optimization for maximum fundamental frequency and minimum cost of hybrid graphene/fibre-reinforced nanocomposite laminates

The present article proposes a multi-objective optimization study aiming at the optimal cost-effective design of nano-reinforced laminates. To maximize the fundamental frequency and minimize the cost, a hybrid laminate is studied, introducing both conventional fibres and graphene nanoplatelets reinforcement. A multi-objective genetic algorithm optimization is adopted to provide the optimal natural frequency and cost for the laminate. Optimization is implemented using the Non-dominated Sorting Genetic Algorithm II (NSGA-II), which converges to near-optimal solutions for all scenarios tested. The vibration problem is solved using the finite element method and the first-order shear deformation theory. Effective material properties are derived using micromechanical equations. Different optimization problems are solved using one to four types of design variables, including graphene and fibre distribution along the thickness, layer thickness, and fibre angles. Results indicate that increasing the graphene nanoplatelets content and keeping the minimum fibre content leads to cost-effective design. A drastic increase in the fundamental frequency and decrease in the cost is obtained for the hybrid graphene/fibre-reinforced laminate compared to conventional fibre-reinforced composites.

Layup optimization of tow-steered composite laminates for maximum fundamental frequency and flutter speed using differential evolution

Layup optimization of tow-steered composite laminates for maximum fundamental frequency and flutter speed using differential evolution

Voice Improvement after Voice Therapy in Female Patients with Unilateral Vocal Fold Paralysis after Thyroid Surgery

Introduction: Dysphonic voice is present in patients with unilateral vocal fold paralysis (UVFP). The aim of this study was to present outcomes following rehabilitation of patients with UVFP, performed according to a voice therapy protocol. Methods: This prospective study comprised 27 women with UVFP who underwent pre- and post-voice therapy assessment. The mean age of patients was 53.19 ± 10.06 years. The protocol included the following: (1) multidimensional assessment of voice quality before treatment; (2) digital laryngeal manipulation voice therapy; (3) voice therapy evaluation which implied repeated multidimensional assessment of voice. Results: The results showed improvement in voice quality following voice therapy with regard to the parameters of the objective voice analysis (maximum fundamental frequency of voice, minimum intensity of voice, jitter, shimmer, harmonics-to-noise ratio, and signal-to-noise ratio, p ˂ 0.05), maximum phonation time, subjective analysis of voice, as well as self-assessment of voice quality on all the subscales and overall score (p ˂ 0.001). Conclusion: Implementing a protocol provides clear guidelines at each stage of the treatment. Voice therapy performed using digital laryngeal manipulation improves the majority of the acoustic and perceptual characteristics of the voice.

Stacking sequence optimization of arbitrary quadrilateral laminated plates for maximum fundamental frequency by hybrid whale optimization algorithm

A Hybrid Whale Optimization Algorithm (HWOA) is proposed to optimize the stacking sequence of arbitrary quadrilateral composite plates. By introducing an adversarial learning strategy, a broader search is performed on the initial domain to generate a better initial population. The mutation operator and opposition-based learning (OBL) strategy of the differential evolution (DE) algorithm are combined to maintain the diversity of the evolutionary process. In addition, the nonlinear convergence factor is introduced to improve the global exploration ability of HWOA when dealing with discrete problems. The stacking sequences of quadrilateral composite plates with different boundary conditions and geometries are optimized to maximize the fundamental frequency. The optimized results of HWOA are compared with those of whale optimization algorithm (WOA), Aquila optimizer (AO), artificial bee colony (ABC) algorithm, DE algorithm and layerwise optimization approach (LOA) algorithm. The results show that HWOA with multiple strategy combinations has good global search capability and robustness, and thus HWOA is a good candidate optimization algorithm for composite plate optimization.

Variable stiffness optimization algorithm for vibration optimization of variable-stiffness composite plates

A novel variable stiffness optimization (VSO) algorithm is proposed for vibration optimization of variable-stiffness composite (VSC) plates uisng linear variation fiber path function. Firstly, an independent 2D-sampling optimization method (2DSOind) is employed to generate a good initial point. Then, optimization is conducted in multiple phases, within each phase, the problem is simplified to an approximately one-dimensional linear search problem. By dividing the fiber angles into two groups, VSO algorithm designs the laminate between two fiber angle groups sequentially and iteratively, making the stiffness of VSC plate stiffened part by part. Lastly, the VSC plate is redesigned accounting for the curvature constraint. The sequential permutation search (SPS) algorithm is coupled into VSO to optimize one group of fiber angles whilst the angles of another group are fixed during the iteration. Under a variety of boundary conditions, the free vibration frequencies of VSC plates are optimized using VSO. In comparison to conventional layerwise optimization (LO) and genetic algorithm (GA), the present results demonstrate much higher efficiency and similar robustness. Moreover, the maximum fundamental frequency of VSC plates can be improved by about 10% in comparison to straight fiber laminates.

Finger Kazoo Intensive Short-term Vocal Therapy: Vocal and Aerodynamic Measurements in Female Teachers

Objectiveto verify the effect after short-term intensive therapy with the Finger Kazoo technique on vocal and aerodynamic measures of dysphonic female teachers. Methodblind randomized clinical trial. Fifteen female teachers without structural disorders of vocal folds and nine with vocal nodules participated in the study groups. Yet, nine female teachers without structural disorders and eight with vocal nodules in the control groups. The following variables were measured pre and post-therapy: minimum and maximum fundamental frequency: forced vital capacity; simple phonic coefficient; compound phonic coefficient; ratio between maximum phonation time of /a/ and expected maximum phonation time. Resultsno statistical significance was observed in the intra and intergroup analyses in any of the measures. Conclusionin this group of female teachers, it was not possible to show a positive effect of short-term and intensive therapy with the Finger Kazoo technique on the vocal measures of minimum and maximum fundamental frequency, forced vital capacity, simple phonic coefficient, compound phonic coefficient, and the relationship between maximum phonation time of /a/ and expected maximum phonation time.