Maximum Pitch Research Articles

Variability in Baseball Throwing Metrics During A Structured Long-toss Program: Does One Size Fit All?

Objectives: The variability of throwing metrics, particularly elbow torque and ball velocity, during structured long-toss programs is yet to be fully elucidated. The primary aims of this study were to assess various throwing metrics through a structured long-toss program using wearable technology and to quantify the intra and inter thrower variability of these metrics at each stage of throwing. Methods: This was a descriptive laboratory study in which 60 high school and collegiate pitchers participated in a predetermined, structured, progressive long-toss program. All players wore a motusBASEBALL sleeve (Motus Global, Inc.; Rockville Centre, NY), which measured arm slot, arm velocity, shoulder rotation, and elbow varus torque. Radar guns were used to measure ball velocity. These metrics were compared within and between all pitchers at each of the following throwing distances: 90 ft, 120 ft, 150 ft, 180 ft, and maximum effort mound pitching. Intra- and inter- thrower reliabilities were calculated for each throwing metric at every stage of the program. Excellent intra-thrower reliability was defined by an Intra-class coefficient (ICC) >0.750. Acceptable inter-thrower reliability was defined by a Coefficient of Variation (CV) <5%. Results: Ball velocity significantly changed at each progressive throwing distance, but this did not consistently correlate with an increase in elbow torque. Pitching from the mound did not place more torque on the elbow than throwing from 120 ft and beyond. Intra-thrower reliability was excellent throughout the progressive long-toss program for each throwing metric. Ninety-one percent of throwers had acceptable inter-thrower reliability for ball velocity, whereas only 79% of throwers had acceptable inter-thrower reliability for elbow torque. Conclusion: Based on trends in elbow torque, it may be practical to incorporate pitching from the mound earlier in the program (once a player is comfortable throwing from 120 ft). Ball velocity and elbow torque do not necessarily correlate with one another, so a degree of caution should be exercised when using radar guns to estimate elbow torque. Given the variability in elbow torque between throwers, some athletes would likely benefit from an individualized throwing program.

Numerical investigation of auto-pitch wing-in-ground effect oscillating foil propulsor

The propulsive characteristics of auto-pitch wing-in-ground effect oscillating foil propulsors (APWIGs) were numerically investigated through an unsteady Reynolds Averaged Navier-Stokes solver. The kinematics of such a biplane configuration is characterized by the prescribed heave motion and flow-induced pitch motion restrained by a torsional spring for each foil. Based on the validated numerical model, the comparison of propulsive performance between APWIGs and single auto-pitch oscillating foil, as well as dual-foil heave-only configuration, was conducted at different advance speeds. Results show that APWIGs is advantageous in both thrust production and efficiency enhancement over other two configurations due to the resulting wing-in-ground effect and substantial reduction of flow separation by the flow-regulated pitch motion. Furthermore, the effect of torsional spring stiffness on the propulsion of APWIGs was studied under different loaded conditions. It was found that both the maximum pitching angle and phase difference of pitch with heave are dramatically affected by the spring stiffness, which has major contribution to the hydrodynamic behaviours of the foils. Under a certain operating speed, an optimal torsional spring stiffness that produces the best propulsive performance can be found. With respect to the parametric space in the current study, the APWIGs can achieve a constant high efficiency over 70% by employing an appropriate spring stiffness.

Experimental identification of the fluid-elastic coupling forces on a flexible tube within a rigid square bundle subjected to single-phase cross-flow

The importance of fluid-elastic coupling forces in tube bundle vibrations is well documented and can hardly be over-emphasized, in view of their damaging potential. Even when adequate tube supports are provided to suppress fluid-elastic instabilities, the flow-coupling forces still affect the dynamical tube responses and remain a significant issue, in particular concerning the vibro-impact motions of tubes assembled using clearance supports. Therefore, the need remains for more advanced models of fluid-elastic coupling, as well as for experimental flow-coupling coefficients to feed and validate such models. In this work, we report an extensive series of experiments performed at CEA-Saclay leading to the identification of stiffness and damping fluid-elastic coefficients, for a 3×5 square tube bundle (D = 30 mm, P/D = 1.5) subjected to single-phase transverse flow, in a water test-loop. The bundle is rigid, except for the central tube which is mounted on a flexible suspension (two parallel steel blades) allowing for translation motions of the tube in the lift direction. The system is thus single-degree of freedom, allowing fluid-elastic instability to arise through a negative damping mechanism. The flow-coupling stiffness and damping coefficients, Kf(Vr) and Cf(Vr), are experimentally identified as functions of the reduced velocity Vr. The maximum value of the Reynolds number ranged from 105 to 2.16 105 (based on the maximum pitch velocity), according to the tested configuration. Identification is achieved on the basis of changes in tube vibration frequency and reduced damping as a function of flow velocity, assuming a constant fluid added mass. In the present experiments, coefficient identification is performed well beyond the instability boundary, by using active control, thereafter allowing exploration of a significant range of flow velocity. The modal frequency and the modal mass of the system are respectively modified by changing the tube suspension stiffness, and/or by adding a mass to the system. We can thus assert how the fluid-elastic coefficients change, for this configuration, with these two system parameters, all other parameters being kept constant. The results obtained from the configurations tested suggest that formulations for coefficient reduction may be improved, in order to better collapse the identified data.

Propulsive efficiency and structural response of a sandwich composite propeller

Studying the sandwich composite propeller (SCMP) is of great significance since the sandwich structure is lightweight and possesses high strength. This study proposes and verifies a fluid–structure interaction (FSI) method for a 3D underwater sandwich composite structure to calculate the performance of the propeller. The Reynolds-averaged Navier–Stokes formula-based computational fluid dynamics is adopted to solve for propeller loads, whereas the finite element method (FEM) is applied to solve for propeller deformations. ANSYS Workbench’s system coupling is utilized to deliver the loads and deformations in the FSI. The paper also compares the propulsive performance and structural response of the SCMP and conventional composite propeller (CMP). The impact of the structural form and core material on the SCMP is explored. The results show that the weight reduction effect of the SCMP is better than that of the CMP, the propulsive efficiency of the SCMP is higher at low advance coefficients and lower at high advance coefficients, and the maximum pitch angles of the SCMP decrease at all conditions, unlike the case for the CMP. Moreover, the thinner the facing of the SCMP, the greater the influence of the higher twist–deformation ratio of the resulting structural form on the intrinsic frequency.

A Study of the Impact of Pitch Misalignment on Wind Turbine Performance

Pitch angle control is the most common means of adjusting the torque of wind turbines. The verification of its correct function and the optimization of its control are therefore very important for improving the efficiency of wind kinetic energy conversion. On these grounds, this work is devoted to studying the impact of pitch misalignment on wind turbine power production. A test case wind farm sited onshore, featuring five multi-megawatt wind turbines, was studied. On one wind turbine on the farm, a maximum pitch imbalance between the blades of 4.5 ° was detected; therefore, there was an intervention for recalibration. Operational data were available for assessing production improvement after the intervention. Due to the non-stationary conditions to which wind turbines are subjected, this is generally a non-trivial problem. In this work, a general method was formulated for studying this kind of problem: it is based on the study, before and after the upgrade, of the residuals between the measured power output and a reliable model of the power output itself. A careful formulation of the model is therefore crucial: in this work, an automatic feature selection algorithm based on stepwise multivariate regression was adopted, and it allows identification of the most meaningful input variables for a multivariate linear model whose target is the power of the wind turbine whose pitch has been recalibrated. This method can be useful, in general, for the study of wind turbine power upgrades, which have been recently spreading in the wind energy industry, and for the monitoring of wind turbine performances. For the test case of interest, the power of the recalibrated wind turbine is modeled as a linear function of the active and reactive power of the nearby wind turbines, and it is estimated that, after the intervention, the pitch recalibration provided a 5.5% improvement in the power production below rated power. Wind turbine practitioners, in general, should pay considerable attention to the pitch imbalance, because it increases loads and affects the residue lifetime; in particular, the results of this study indicate that severe pitch misalignment can heavily impact power production.

Numerical Investigation of the Effects of Nonsinusoidal Motion Trajectory on the Propulsion Mechanisms of a Flapping Airfoil

The effect of nonsinusoidal trajectory on the propulsive performances and the vortex shedding process behind a flapping airfoil is investigated in this study. A movement of a rigid NACA0012 airfoil undergoing a combined heaving and pitching motions at low Reynolds number (Re = 11,000) is considered. An elliptic function with an adjustable parameter S (flattening parameter) is used to realize various nonsinusoidal trajectories of both motions. The two-dimensional (2D) unsteady and incompressible Navier–Stokes equation governing the flow over the flapping airfoil are resolved using the commercial software starccm+. It is shown that the nonsinusoidal flapping motion has a major effect on the propulsive performances of the flapping airfoil. Although the maximum propulsive efficiency is always achievable with sinusoidal trajectories, nonsinusoidal trajectories are found to considerably improve performance: a 110% increase of the thrust force was obtained in the best studied case. This improvement is mainly related to the modification of the heaving motion, more specifically the increase of the heaving speed at maximum pitching angle of the foil. The analysis of the flow vorticity and wake structure also enables to explain the drop of the propulsive efficiency for nonsinusoidal trajectories.

응용 입술 트릴 훈련이 뮤지컬 전공 학생의 음성 변화에 미치는 효과

The Modified Voiced Lip Trill (MVoLT) training is a variant of voiced lip-till training characterized by increased loudness, lowered laryngeal position, and lip contact facilitated with fingers. The purpose of the current study was to assess the effect of the MVoLT training program on vocal changes of musical singing theater students. A total of 32 musical theater students (17 males and 15 females, age ranging from 18 to 29) participated in the study. For about three months, each participant was tutored using a systematic program focussing on the MVoLT training, accompanied by certain facilitating strategies. Pre- & post-training multi-dimensional vocal characteristics were assesed and compared. Results showed that cepstral peak prominence during vowel phonation increased after training, while its standard deviation and Cepstral Spectral Index of Dysphonia decreased. When an aerodynamic assessment was performed, maximum phonation time, subglottal pressure, mean airflow rate increased, while electroglottographic measures did not change. In addition, decreased psychometric measures, higher maximum pitch, and increased vocal range were noted after training. In conclusion, the MVoLT was proven to have a potential as an effective and safe training method for musical theater singing.

Postquarter-Point Case of Ship’s Side-Berthing and Its Influence on Marine Fender Pitch

This paper presents a critical analysis of some selected codes and practical recommendations used as basic rules in the design procedures of modern marine fender systems. The first part of the discussion pertains to the existing equations used in calculating the eccentricity coefficient in the ship’s kinetic energy equation and the maximum allowable fender pitch (spacing) in a set of fenders installed along a quay wall. A new approach for the single-fender ship-to-fender contact mode during the side-berthing procedure is introduced, assuming three different special cases (i.e., the prequarter-point case, the quarter-point case, and the postquarter-point case) of the relative position of the ship’s hull with respect to the compressed fender unit. New equations are proposed for the maximum allowable fender pitch and the extreme berthing angles associated with the postquarter-point case of the single-fender and two-fender contact modes. Taking a ferry contact with an MV-type (or pi-type) modular fender as an example, a detailed computational analysis has been performed, illustrating permissible geometrical ship-fender-quay configurations and their influence on the eccentricity coefficient, and, consequently, on the effective kinetic energy of a berthing ship.

Pelvic pitch and roll during total hip arthroplasty performed through a posterolateral approach. A potential source of error in free-hand cup positioning.

Intraoperative pelvic motion can alter the perceived cup inclination and version during non-navigated THA. We quantified pelvic motion during different phases of primary THA performed in the lateral decubitus through a posterolateral approach. Pelvic roll (rotation of the coronal plane) and pitch angles (rotation parallel to the coronal plane) were studied in 75 patients undergoing THA for osteoarthritis by four arthroplasty surgeons. Ten steps of surgery were defined. Angular motion was recorded with a miniature surgical device that utilizes inertial sensors. The mean absolute roll ranged from 0.03° detected at the end of surgery to 4.13° detected during acetabular exposure. The mean absolute pitch ranged from 0.05° detected at the end of surgery to 2.54° detected during hip dislocation. The maximum pelvic roll and pitch detected during surgery averaged 17.62° (SD: 5.08) and 9.3° (SD: 3.39) respectively. Absolute roll and pitch angles were not affected by patient's BMI, sex, pre-operative hip motion, or surgeon. Before cup insertion, the greatest mean change in roll was observed during acetabular exposure (10.02° anteriorly), and for pitch was observed during dislocation (1.88° caudally). During THA performed through a posterolateral approach, there is a progressive anterior pelvic roll that peaks before cup insertion. This can lead to underestimation of cup anteversion during non-navigated THA. The anterior roll does not completely correct, even when all retractors and external forces acting on the pelvis are removed. Pelvic pitch that could affect the perceived cup inclination occurs to a lesser extent than pelvic roll.

Power extraction performance of three types of flapping hydrofoils at a Reynolds number of 1.7E6

Abstract This work focuses on the hydrodynamic performance analyses of three different types of flapping hydrofoils, in this case the pitch-heave (PH), left-swing (LS), and right-swing (RS) types, in their power extraction regimes via two dimensional CFD simulations. The power extraction performance is presented in an isocontour parametric map and is investigated from a comparison of the kinematics parameters and the development of unsteady vortices among the three types. It is found from the parametric analysis and comparison that the LS-type of flapping hydrofoil outperforms the PH and RS-types due to relatively high forces as well as the good synchronization of the forces and moment with the translational velocity and pitch angular rate, respectively upon the different aspects of the vortex development. Consequently, the power extraction performance improves from the LS to the PH and then to the RS-types. It is also recognized from another isocontour parametric map that the maximum power-extraction efficiency is achieved at a similar maximum effective angle of attack, at the maximum effective angle of attack rate, and at the maximum pitch angle rate for the LS and RS types, while the range of the maximum effective angle of attack rate is lower in the PH-type hydrofoil.

Laser-controlled adaptive optics for beam quality improvements in a multi-pass thin-disk amplifier.

We devise a laser-controlled adaptive optical element that operates intracavity under high-intensity radiation. This element substitutes a conventional mechanically deformable mirror and is free of critical heat-sensitive components and electronics. The deformation mechanism is based on the projection of a continuous-wave control laser onto a specially designed mirror. Mounted to a water-cooled heat sink, the mirror can handle laser radiation beyond 3 MW/cm2. The properties of the adaptive optical element, including the maximum correctable wavefront pitch of 800nm, are discussed. The successful implementation in a multi-pass thin-disk amplifier is presented. An improvement of the beam quality by a factor of three is achieved. We identify measures to enhance the performance of the adaptive optics towards efficient operation in a high-power laser system.

Experimental study and modelling of unsteady aerodynamic forces and moment on flat plate in high amplitude pitch ramp motion

This paper examines the unsteady lift, drag and moment coefficients experienced by a thin airfoil in high-amplitude pitch ramp motion. Experiments have been carried out in a wind tunnel at moderate Reynolds number ($Re\approx 1.45\times 10^{4}$), using a rigid flat-plate model. Forces and moments have been measured for reduced pitch rates ranging from 0.01 to 0.18, four maximum pitch angles ($30^{\circ },45^{\circ },60^{\circ },90^{\circ }$) and different pivot axis locations between the leading and the trailing edge. Results confirm that for reduced pitch rates lower than 0.03, the unsteady aerodynamics is limited to a stall delay effect. For higher pitch rates, the unsteady response is dominated by a buildup of the circulation, which increases with the pitch rate and the absolute distance between the pivot axis and the $3/4$-chord location. This circulatory effect induces an overshoot in the normal force and moment coefficients, which is slightly reduced for a flat plate with a finite aspect ratio close to 8 in comparison with the two-dimensional configuration. A new time-dependent model has been tested for both the normal force and moment coefficients. It is mainly based on the superposition of step responses, using the Wagner function and a time-varying input that accounts for the nonlinear variation of the steady aerodynamics, the pivot point location and an additional circulation which depends on the pitch rate. When compared with experiments, it gives satisfactory results for $0^{\circ }$ to $90^{\circ }$ pitch ramp motion and captures the main effect of reduced pitch rate and pivot point location.

What's in a word: Sounding sarcastic in British English

Using a simulated telephone conversation task, we elicited sarcastic production in different utterance types (i.e. declaratives, tag questions andwh-exclamatives from native speakers of the southern variety of British English. Unlike previous studies which focus on static prosodic measurements at the utterance level (e.g. mean pitch, pitch span, intensity), we examined both static prosodic measurements and continuous changes in contour shape in the semantically most important words (or key words) of the sarcastic utterances and their counterparts in the sincere utterances. To this end, we adopted Functional Data Analysis to model pitch variation as contours and represent the contours as continuous function in statistical analysis. We found that sarcasm and sincerity are prosodically distinguishable in the key words alone. The key words in sarcastic utterances are realised with a longer duration and a flatter fall than their counterparts in sincere utterances regardless of utterance type and speaker gender. These results are compatible with previous reports on the use of a smaller pitch span and a slower speech rate in sarcastic utterances than in sincere utterances in North American English. We also observed notable differences in the use of minimum pitch, maximum pitch and contour shape in different utterance types and in the use of mean pitch and duration by male and female speakers. Additionally, we found that the prosody of the key words in sarcastic utterances and their counterparts in sincere utterances has yielded useful predictors for the presence (or absence) of sarcasm in an utterance. Together, our results lend direct support to a key-word–based approach. However, the prosodic predictors included in our analysis alone can achieve only an accuracy of 70.4%, suggesting a need to examine additional prosodic parameters and prosody beyond the key words.

The sound of Passion and Indifference

Extending affective speech communication research in the context of authentic, spontaneous utterances, the present study investigates two signals of affect defined by extreme levels of physiological arousal—Passion and Indifference. Exemplars were mined from podcasts conducted in informal, unstructured contexts to examine communication at extreme levels of perceived hyper- and hypo-arousal. Utterances from twenty native speakers of Canadian/American English were submitted for perceptual validation for judgments of affective meaning (Passion, Indifference, or Neutrality) and level of arousal (“Not At All” to “Very Much”). Arousal ratings, acoustic patterns, and linguistic cues (affect/emotion words and expletives) were analyzed. In comparison to neutral utterances, Passion was communicated with the highest maximum pitch and pitch range, and highest maximum and mean amplitude, while Indifference was communicated via decreases in these measures in comparison to neutral affect. Interestingly, Passion and Neutrality were expressed with comparable absolute ranges of amplitude, while the minimum amplitudes of both Passion and Indifference were greater than those of Neutral expressions. Linguistically, Indifference was marked by significantly greater use of explicit expressions of affect (e.g. I don't care…), suggesting a linguistic encoding preference in this context. Passion was expressed with greater use of expletives; yet, their presence was not necessary to facilitate perception of a speaker's level of arousal. These findings shed new light upon the paralinguistic and linguistic features of spontaneous expressions at the extremes of the arousal continuum, highlighting key distinctions between Indifference and Neutrality with implications for vocal communication research in healthy and clinical populations.

Experimental study on motion responses of a moored rectangular cylinder under freak waves (I: Time-domain study)

Extensive experiments on the motion responses of a rectangular cylinder under random and freak waves have been conducted in the present study. The effects of the relative wave height, relative period and freak wave parameters on the motion responses were investigated. Analysis in time-domain revealed that the freak wave parameter α1 has significant effect on the motion responses of the cylinder, especially for surge and heave. However, α2, α3, α4 have not such significant effect on the motion components. With α1 = 2–2.8, the maximum surge and heave under freak waves were 2.5 and 1.5 times, respectively, larger than those under irregular waves. In addition, the maximum pitch under freak waves was approximately 1.3 times of that under irregular waves. The difference in motion response under freak waves and irregular waves decreased with the increasing relative wave heights. With Hs/d = 0.03–0.1 and α1 = 2–2.2, the maximum surge and heave under freak waves were approximately 30–60% and 20–40%, respectively, larger than those under irregular waves. For the effect of the relative period, the critical surge, heave and pitch occur at period around Tp/T0heave ˜ 1.0, 1.5, 2.0 and Tp/T0pitch ˜ 1, respectively. With the natural periods and α1 = 2–2.2, surge, heave and pitch under freak waves were approximately 44%, 40% and 30%, respectively, larger than those under irregular waves.

An Energetic Electron Flux Dropout Due to Magnetopause Shadowing on 1 June 2013

AbstractWe examine the mechanisms responsible for the dropout of energetic electron flux during 31 May to 1 June 2013 using Van Allen Probe (Radiation Belt Storm Probes (RBSP)) electron flux data and simulations with the Comprehensive Inner Magnetosphere‐Ionosphere (CIMI) model. During the storm main phase, L‐shells at RBSP locations are greater than ~8, which are connected to open drift shells. Consequently, diminished electron fluxes were observed over a wide range of energies. The combination of drift shell splitting, magnetopause shadowing, and drift loss all results in butterfly electron pitch angle distributions (PADs) at the nightside. During storm sudden commencement, RBSP observations display electron butterfly PADs over a wide range of energies. However, it is difficult to determine whether there are butterfly PADs during the storm main phase since the maximum observable equatorial pitch angle from RBSP is not larger than ~40° during this period. To investigate the causes of the dropout, the CIMI model is used as a global 4‐D kinetic inner magnetosphere model. The CIMI model reproduces the dropout with very similar timing and flux levels and PADs along the RBSP trajectory for 593 keV. Furthermore, the CIMI simulation shows butterfly PADs for 593 keV during the storm main phase. Based on comparison of observations and simulations, we suggest that the dropout during this event mainly results from magnetopause shadowing.

Effect of Bhramari Pranayama on the Acoustic and Aerodynamic Parameters of Voice in Normophonic Females.

Summary. Objective Pranayama is known for improving various health conditions. The present study is aimed at investigating the effects of bhramari pranayama on aerodynamic and acoustic parameters of voice in healthy individuals. Study Design This is a pretest-posttest design study. Methods A total of 24 participants in the age range of 20 to 25 years completed the bhramari pranayama regimen for 30 sessions. Aerodynamic and acoustic assessments were done before and after pranayama sessions. Maximum phonation duration, pitch, loudness, subglottal pressure, glottal airflow, laryngeal resistance and conductance along with acoustical parameters such as average F0, jitter, and shimmer, soft phonation index, noise to harmonic ratio, cepstral peak prominence, and smoothened cepstral peak prominence were analysed. Results The results revealed significant improvement in the maximum phonation duration, glottal airflow and pressure, average fundamental frequency, and cepstral peak prominence after practice suggesting that it has an effect on voice parameters. Conclusion Bhramari pranayama is effective in improving the acoustic and aerodynamic parameters of voice. The same needs to be investigated in hyper- and hypofunctional voice disorders in the future studies.

Characteristics of temporal resolution in 16- and 64-row computed tomography scanners.

This study aimed to analyze the temporal sensitivity profile (TSP) shapes and temporal resolutions of computed tomography (CT) and investigate the effect of a combination of a given rotation time and helical pitch on the TSP and image quality. The study was performed on 16- and 64-row CT scanners, and the TSP and temporal resolution were measured using the impulse method. A shorter gantry rotation time and larger helical pitch improved the temporal resolution of both CT scanners. Although the measured TSP shapes were dependent on the helical pitch, the maximum helical pitch did not improve the temporal resolution of either CT scanner. Different combinations of gantry rotation time and helical pitch yielded different TSP shapes such as the triangle, trapezoid, and rectangle, despite the use of equivalent scan speeds. We suggest that the different combinations of rotation time and helical pitch can greatly affect the TSP shapes.

Our Experience of Medialization Thyroplasty with Freeze-Dried Cadaveric Human Fascia Lata in Unilateral True Vocal Cord Paralysis

Background: Use of autologous fascia, harvested from the thigh fascia lata, has been shown to be effective in the treatment of unilateral vocal fold paralysis (UVFP). However, advantages of this material have been less examined in the clinical setting. The present study aimed to assess the beneficial effects of medialization thyroplasty type I with cadaveric fascia lata on the vocal function of patients with UVFP. Methods: This prospective interventional case series was performed on 10 patients with UVFP, who were candidates for medialization thyroplasty. All the patients were assessed using video stereoscopy to determine the gap and closure of glottis. Voice analysis was also performed. The voice handicap index (VHI) was completed for all the patients. The level of satisfaction with voice quality was also assessed, using the visual analogue scale (VAS). Results: The mean VHI scores significantly decreased at 1, 3, and 6 months after surgery. The mean VAS scores (for voice quality) significantly increased within 1 month after surgery, whereas they gradually decreased at 5 months after surgery. The mean values of minimum and maximum pitch indices were comparable before and after surgery. The mean jitter score decreased at 1 month after surgery, while it remained constant at 6 months after surgery. The mean shimmer score gradually reduced within 3 months after surgery. On the other hand, the mean harmonic/noise ratio (HN/R) significantly increased at 6 months after surgery. The findings showed a significant decline in the frequency of anterior and posterior glottis gaps at all postoperative intervals. Conclusions: Short-term improvement of vocal quality and glottic efficiency, along with reduced glottis gap, is expected following medialization thyroplasty type I with cadaveric fascia lata.

Numerical study on hydrodynamics for a non-sinusoidal forced oscillating hydrofoil based on an immersed boundary method

Fluid-structure investigations in hydraulic machines using coupled simulations based on dynamical re-mesh are particularly time-consuming. This paper presents an implementation of an immersed boundary (IB) method for dynamical boundary flowing problem in a flow solver based on the fractional time step method and the finite different method, which is validated by a basic numerical example. The hydrofoil, which is surrounded by incompressible flow, is modeled with forced pitching motions. To seek better understanding of the coupled hydrodynamic performance of an oscillating (fully active) hydrofoil, a forced motion of non-sinusoidal oscillating is investigated for different pitching frequencies f and maximum angle amplitude θ0 as well as profile parameter β. Effects of non-sinusoidal pitching motion on the hydrodynamic load and power input performance are investigated under different pitching motional parameters. The results show that the time-averaged input power gradually increases with both the pitching frequency f and profile parameter β while it decreases with the maximum pitching amplitudeθ0. The instantaneous peak value of input power also increases with both the pitching frequency f and profile parameter β rising up. In addition, the flow fields for different motional parameters are discussed. The different vortex evolutions for various β and pitching frequency remind us that the flow around a flapping foil is complicated and strongly related to the unsteady hydrodynamics. The present research results are helpful to control strategy design for the hydrofoil movement in the operating process of turbine unit.