An Experimental Study of Pulsatile Flow in Canine Larynges

1995 ◽  
Vol 117 (4) ◽  
pp. 577-581 ◽  
Author(s):  
F. Alipour ◽  
R. C. Scherer ◽  
V. C. Patel
Keyword(s):  
Flow Rate ◽  
Pulsatile Flow ◽  
Vocal Fold ◽  
Computational Models ◽  
Volume Flow Rate ◽  
Air Velocity ◽  
Sustained Oscillations ◽  
Subglottal Pressure ◽  
The Mean ◽  
Oscillation Frequencies

Pulsatile flow in an excised canine larynx was investigated with simultaneous recordings of air velocity, subglottal pressure, volume flow rate, and the signal from an electro-glottograph (EGG) for various conditions of phonation. Canine larynges were mounted on a pseudotrachea and sustained oscillations were established and maintained with sutures attached to cartilages to mimic the function of laryngeal muscles. The pitch and amplitude of the oscillations were controlled by varying the airflow, and by adjusting glottal adduction and vocal-fold elongation. Measurements with hot-wire probes suggest that subglottal inlet flow to the larynx is pulsatile but mostly laminar, while the exiting jet is non-uniform and turbulent. In the typical ranges of flow rate, subglottal pressure, and oscillation frequencies, the Reynolds number based on the mean glottal velocity and glottal hydraulic diameter varied between 1600 to 7000, the Strouhal number based on the same parameters varied between 0.002 and 0.032, and the Womersley number ranged from 2.6 to 15.9. These results help define the conditions required for computational models of laryngeal flow.

scholarly journals Automobile Radiator’s Engineering and Analysation

2020 ◽  
Vol 9 (5) ◽  
pp. 554-558
Keyword(s):  
Flow Rate ◽  
Heat Dissipation ◽  
Cooling System ◽  
Volume Flow Rate ◽  
Air Flow ◽  
Temperature Drop ◽  
Inlet Temperature ◽  
Air Flow Rate ◽  
Air Velocity ◽  
Cooling Fan

The shape of a radiator cover is crucial either in determining the pattern of air flow or in increasing the same through the radiator core thereby increasing the thermal efficiency, thus making it a necessity to understand it. Moreover the parts circumjacent to the core namely the upper tank, lower tank, cooling fan, fins, tubes, etc promote the air flow rate. Also it is to note that the air flow rate of discharge gases from radiator core is one of the prime factors in determining the automobile cooling system. Initially factors such as temperature, pressure, air flow rate that affect the performance are obtained in order to derive out the entities of operation. One of the observations that can be made through this paper is that as the volume of the coolant increases, the rate of heat dissipation increases, also parameters like inlet temperature and volume flow rate of coolant, air velocity, temperature drop and drop in pressure of coolant are factors that contribute in radiator performance evidently.

Nonlinear Vocal Fold Dynamics in a Two-Mass Model of Speech Arising From Asymmetric Intraglottal Flow

2011 ◽  
Author(s):  
Byron D. Erath ◽  
Matías Zañartu ◽  
Sean D. Peterson ◽  
Michael W. Plesniak
Keyword(s):  
Vocal Fold ◽  
Vocal Tract ◽  
Vocal Folds ◽  
Attractive Alternative ◽  
Nonlinear Phenomena ◽  
Mass Model ◽  
Sustained Oscillations ◽  
Voiced Speech ◽  
Subglottal Pressure ◽  
Vocal Fold Dynamics

Voiced speech is initiated as air is expelled from the lungs and passes through the vocal tract inciting self-sustained oscillations of the vocal folds. While various approaches exist for investigating both normal and pathological speech, the relative inaccessibility of the vocal folds make multi-mass speech models an attractive alternative. Their behavior has been benchmarked with excised larynx experiments, and they have been used as analysis tools for both normal and disordered speech, including investigations of paralysis, vocal tremor, and breathiness. However, during pathological speech, vocal fold motion is often unstructured, resulting in chaotic motion and a wealth of nonlinear phenomena. Unfortunately, current methodologies for multi-mass speech models are unable to replicate the nonlinear vocal fold behavior that often occurs in physiological diseased voice for realistic values of subglottal pressure.

Velocity and size characteristics of liquid-fuelled flames stabilized by a swirl burner

1990 ◽  
Vol 428 (1874) ◽  
pp. 129-155 ◽  
Keyword(s):  
Flow Rate ◽  
Elevated Temperatures ◽  
Outer Part ◽  
Arithmetic Mean ◽  
Recirculation Region ◽  
Reacting Flow ◽  
Air Velocity ◽  
Flow Rates ◽  
The Mean ◽  
Air Motion

Velocity and droplet size characteristics of an unconfined quarl burner, of 16 mm quarl inlet diameter, have been measured with a phase-Doppler anemometer at a swirl number of about 0.29: the Reynolds number of the flow was 30000, based on the cold bulk velocity of 30.4 m s -1 and the hydraulic diameter. The atomization was achieved by shear between the swirling air and six radial kerosene jets and the resulting Sauter and arithmetic mean diameters were about 70 and 50 μm respectively after injection: velocity characteristics are presented for three 5 μm-wide size classes, 10, 30 and 60 μm. The flows correspond to no combustion and combustion of natural gas with a heat release of 8 kW supplemented by liquid kerosene flow rates sufficient to generate 21.6 and 37.2 kW : the gas equivalence ratio was 0.45 and atomized kerosene at two flow rates increased the overall ratios to 1.64 and 2.53. In non­-reacting flow, droplets 30 μm and smaller are sufficiently small to be entrained by the mean air velocity towards the central part of the flow and into the swirl-induced recirculating air bubble. The 60 μm droplets are able to travel through the bubble uninfluenced by turbulent fluctuations in the air and are ‘centrifuged’ away from the centreline, through acquisition of a mean swirl velocity component, so that a large proportion of the kerosene volume flow rate lies at the edge of the swirling jet. Because larger droplets are centrifuged to the outer part of the flow, whereas the smaller are entrained towards the centreline, the Sauter and arithmetic mean diameters are, by 1.22 quarl exit diameters downstream of the quarl, approximately 65 and 36 μm at the outer part of the flow and 35 and 12 μm near the centreline in the inert flow. In reacting flow, droplets evaporate rapidly in regions of elevated temperatures and hence no droplets are found within the flame brush and recirculation region. The aerodynamic response of each size class to the air velocity is similar to inert flow so that the majority of the kerosene flow is centrifuged away from the flame. On exit from the quarl, the evaporation and burning rates cause the Sauter and arithmetic mean diameters to be about 70 and 50 μm and 60 and 30 μm at the inner and outer edges of the spray respectively. By 1.22 quarl exit-diameters from the exit of the quarl, the air motion entrains droplets smaller than about 30 μm towards the flame, at the inner edge of the spray, so that the Sauter and arithmetic mean diameters are 60 and 40 μm at the outer edge of the jet. There is comparatively little effect of changing the flow rate of kerosene because the combustion is controlled by the low available number of smaller droplets, although the Group combustion number corresponds to ‘cloud’ burning. The relative response of droplets to the mean and turbulent components of air motion, including the ‘centrifuging’ effect, can be scaled to other flows through dimensionless numbers defined in the text.

Parameters Dependence of Fibers Diameter and Pores Area in Electrospinning

2018 ◽  
Vol 26 ◽  
pp. 67-73 ◽  
Author(s):  
Emilija Zdraveva ◽  
Budimir Mijovic
Keyword(s):  
Flow Rate ◽  
Polyethylene Oxide ◽  
Volume Flow Rate ◽  
Processing Parameters ◽  
Critical Value ◽  
Volume Flow ◽  
Production Technique ◽  
The World ◽  
The Mean ◽  
Two Parameters

Electrospinning has become the most popular nanofibers production technique that many scientists around the world were intrigued by. It is based on electrostatic forces stretching a polymer solution that undergoes bending instability and eventually results in number of fine nanoscaled filaments. The study reports of four processing parameters effect on electrospun polyethylene oxide (PEO) fibers diameter and pores area. Fibers diameter increase results from the increase of time, volume flow rate and tip to collector distance with a critical value of the first two parameters. The pores area showed both decrease and increase after a critical value of the electrical voltage at 19 kV, while the mean pores area decreased with the time increase. Irregular trends of increasing and decreasing trends of the means pores area were noticed with the change of the volume flow rate and tip to collector distance..

scholarly journals Estimation of Subglottal Pressure, Vocal Fold Collision Pressure, and Intrinsic Laryngeal Muscle Activation From Neck-Surface Vibration Using a Neural Network Framework and a Voice Production Model

2021 ◽  
Vol 12 ◽  
Author(s):  
Emiro J. Ibarra ◽  
Jesús A. Parra ◽  
Gabriel A. Alzamendi ◽  
Juan P. Cortés ◽  
Víctor M. Espinoza ◽  
...  
Keyword(s):  
Vocal Fold ◽  
Muscle Activation ◽  
Production Model ◽  
Vocal Function ◽  
Voice Production ◽  
Laryngeal Muscle ◽  
Surface Vibration ◽  
Subglottal Pressure ◽  
The Mean ◽  
Collision Pressure

The ambulatory assessment of vocal function can be significantly enhanced by having access to physiologically based features that describe underlying pathophysiological mechanisms in individuals with voice disorders. This type of enhancement can improve methods for the prevention, diagnosis, and treatment of behaviorally based voice disorders. Unfortunately, the direct measurement of important vocal features such as subglottal pressure, vocal fold collision pressure, and laryngeal muscle activation is impractical in laboratory and ambulatory settings. In this study, we introduce a method to estimate these features during phonation from a neck-surface vibration signal through a framework that integrates a physiologically relevant model of voice production and machine learning tools. The signal from a neck-surface accelerometer is first processed using subglottal impedance-based inverse filtering to yield an estimate of the unsteady glottal airflow. Seven aerodynamic and acoustic features are extracted from the neck surface accelerometer and an optional microphone signal. A neural network architecture is selected to provide a mapping between the seven input features and subglottal pressure, vocal fold collision pressure, and cricothyroid and thyroarytenoid muscle activation. This non-linear mapping is trained solely with 13,000 Monte Carlo simulations of a voice production model that utilizes a symmetric triangular body-cover model of the vocal folds. The performance of the method was compared against laboratory data from synchronous recordings of oral airflow, intraoral pressure, microphone, and neck-surface vibration in 79 vocally healthy female participants uttering consecutive /pæ/ syllable strings at comfortable, loud, and soft levels. The mean absolute error and root-mean-square error for estimating the mean subglottal pressure were 191 Pa (1.95 cm H2O) and 243 Pa (2.48 cm H2O), respectively, which are comparable with previous studies but with the key advantage of not requiring subject-specific training and yielding more output measures. The validation of vocal fold collision pressure and laryngeal muscle activation was performed with synthetic values as reference. These initial results provide valuable insight for further vocal fold model refinement and constitute a proof of concept that the proposed machine learning method is a feasible option for providing physiologically relevant measures for laboratory and ambulatory assessment of vocal function.

scholarly journals Direct Measurements of the Volume Flow Rate and Emissions in a Large Naturally Ventilated Building

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6223
Author(s):  
David Janke ◽  
Qianying Yi ◽  
Lars Thormann ◽  
Sabrina Hempel ◽  
Barbara Amon ◽  
...  
Keyword(s):  
Flow Rate ◽  
Laser Doppler Anemometry ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Normal Velocity ◽  
Tracer Gas ◽  
Flame Ionization ◽  
Constant Height ◽  
Emission Estimation ◽  
The Mean

The direct measurement of emissions from naturally ventilated dairy barns is challenging due to their large openings and the turbulent and unsteady airflow at the inlets and outlets. The aim of this study was to quantify the impacts of the number and positions of sensors on the estimation of volume flow rate and emissions. High resolution measurements of a naturally ventilated scaled building model in an atmospheric boundary layer wind tunnel were done. Tracer gas was released inside the model and measured at the outlet area, using a fast flame ionization detector (FFID). Additionally, the normal velocity on the area was measured using laser Doppler anemometry (LDA). In total, for a matrix of 65 × 4 sensor positions, the mean normal velocities and the mean concentrations were measured and used to calculate the volume flow rate and the emissions. This dataset was used as a reference to assess the accuracy while systematically reducing the number of sensors and varying the positions of them. The results showed systematic errors in the emission estimation up to +97%, when measurements of concentration and velocity were done at one constant height. This error could be lowered under 5%, when the concentrations were measured as a vertical composite sample.

scholarly journals Subglottal pressure oscillations in anechoic and resonant conditions and their influence on excised larynx phonations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hugo Lehoux ◽  
Vít Hampala ◽  
Jan G. Švec
Keyword(s):  
Vocal Fold ◽  
Computational Models ◽  
Vocal Folds ◽  
Voice Source ◽  
Resonance Frequencies ◽  
Subglottal Pressure ◽  
Radiated Sound ◽  
Acoustic Resonances ◽  
The Impact ◽  
Excised Larynx

AbstractExcised larynges serve as natural models for studying behavior of the voice source. Acoustic resonances inside the air-supplying tubes below the larynx (i.e., subglottal space), however, interact with the vibratory behavior of the larynges and obscure their inherent vibration properties. Here, we explore a newly designed anechoic subglottal space which allows removing its acoustic resonances. We performed excised larynx experiments using both anechoic and resonant subglottal spaces in order to analyze and compare, for the very first time, the corresponding subglottal pressures, electroglottographic and radiated acoustic waveforms. In contrast to the resonant conditions, the anechoic subglottal pressure waveforms showed negligible oscillations during the vocal fold contact phase, as expected. When inverted, these waveforms closely matched the inverse filtered radiated sound waveforms. Subglottal resonances modified also the radiated sound pressures (Level 1 interactions). Furthermore, they changed the fundamental frequency (fo) of the vocal fold oscillations and offset phonation threshold pressures (Level 2 interactions), even for subglottal resonance frequencies 4–10 times higher than fo. The obtained data offer the basis for better understanding the inherent vibratory properties of the vocal folds, for studying the impact of structure-acoustic interactions on voice, and for validation of computational models of voice production.

Novel epoxy/anhydride alternatives for biological electron microscopy: Physical and performance characteristis of embed 812 and LX 112 in combination with NSA/NMA/DMAE

1989 ◽  
Vol 47 ◽  
pp. 1000-1001
Author(s):  
Joe A. Mascorro ◽  
Gerald S. Kirby
Keyword(s):  
Electron Microscopy ◽  
Flow Rate ◽  
Succinic Anhydride ◽  
Volume Flow Rate ◽  
Mass Density ◽  
Uranyl Acetate ◽  
Volume Flow ◽  
Base Resin ◽  
And Performance ◽  
Acid Anhydrides

Embedding media based upon an epoxy resin of choice and the acid anhydrides dodecenyl succinic anhydride (DDSA), nadic methyl anhydride (NMA), and catalyzed by the tertiary amine 2,4,6-Tri(dimethylaminomethyl) phenol (DMP-30) are widely used in biological electron microscopy. These media possess a viscosity character that can impair tissue infiltration, particularly if original Epon 812 is utilized as the base resin. Other resins that are considerably less viscous than Epon 812 now are available as replacements. Likewise, nonenyl succinic anhydride (NSA) and dimethylaminoethanol (DMAE) are more fluid than their counterparts DDSA and DMP- 30 commonly used in earlier formulations. This work utilizes novel epoxy and anhydride combinations in order to produce embedding media with desirable flow rate and viscosity parameters that, in turn, would allow the medium to optimally infiltrate tissues. Specifically, embeding media based on EmBed 812 or LX 112 with NSA (in place of DDSA) and DMAE (replacing DMP-30), with NMA remaining constant, are formulated and offered as alternatives for routine biological work.Individual epoxy resins (Table I) or complete embedding media (Tables II-III) were tested for flow rate and viscosity. The novel media were further examined for their ability to infilftrate tissues, polymerize, sectioning and staining character, as well as strength and stability to the electron beam and column vacuum. For physical comparisons, a volume (9 ml) of either resin or media was aspirated into a capillary viscocimeter oriented vertically. The material was then allowed to flow out freely under the influence of gravity and the flow time necessary for the volume to exit was recored (Col B,C; Tables). In addition, the volume flow rate (ml flowing/second; Col D, Tables) was measured. Viscosity (n) could then be determined by using the Hagen-Poiseville relation for laminar flow, n = c.p/Q, where c = a geometric constant from an instrument calibration with water, p = mass density, and Q = volume flow rate. Mass weight and density of the materials were determined as well (Col F,G; Tables). Infiltration schedules utilized were short (1/2 hr 1:1, 3 hrs full resin), intermediate (1/2 hr 1:1, 6 hrs full resin) , or long (1/2 hr 1:1, 6 hrs full resin) in total time. Polymerization schedules ranging from 15 hrs (overnight) through 24, 36, or 48 hrs were tested. Sections demonstrating gold interference colors were collected on unsupported 200- 300 mesh grids and stained sequentially with uranyl acetate and lead citrate.

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