Acoustic analysis of two small axial-flow fans in series

A comparative acoustic analysis of species of Vitreorana (Anura: Centrolenidae) from the Brazilian Atlantic Forest and Cerrado, with a description of the call of V. baliomma and insights into the taxonomic status of Cerrado populations. Advertisement calls are the primary signaling strategy of mating in most anurans. Examining major patterns within and across frog taxa may help to delimit species and understand acoustic communication systems. Herein, the vocalization of Vitreorana baliomma is described and new acoustic descriptions are provided for V. franciscana and V. eurygnatha. Calls of syntopic/sympatric or allopatric populations were compared. The vocalization of V. baliomma is composed of two call types—A and B, with Call A being the advertisement call. The vocalization of V. franciscana is composed of only one call type (Call A), emitted isolated or in series. The vocalization of V. eurygnatha has two types of calls; Call A is similar among Cerrado populations, whereas an Atlantic Forest population has a distinct Call A pattern. The calls of each of these species of the present study is pulsed; however, the calls differ in call duration, pulse organization, or pulse duration, and these differences seem to reflect the allopatric or sympatric/syntopic occurrences of populations. The unique call pattern of the Atlantic Forest population of V. eurygnatha may represent the advertisement call of the nominal species, and the distinct call of the Cerrado population may indicate cryptic diversity in the species.

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Acoustic Analysis of Condenser Fan of Split Air Conditioner Using Numerical and Experimental Method

International Journal of Air-Conditioning and Refrigeration ◽

10.1142/s2010132515500121 ◽

2015 ◽

Vol 23 (02) ◽

pp. 1550012 ◽

Cited By ~ 1

Author(s):

Nitin Gulhane ◽

Sandip Patil ◽

Kanwaljeet Singh

Keyword(s):

Cfd Simulation ◽

Acoustic Analysis ◽

Three Dimensional ◽

Axial Flow ◽

Accurate Method ◽

Experimental Result ◽

Optimized Design ◽

Air Conditioner ◽

Ansys Fluent ◽

Fan Blade

The present work aims to investigate the accurate method of performing computational fluid dynamics (CFD) — Acoustic analysis for axial flow fans in split air conditioner system. A comprehensive simulation procedure is developed to predict flow-induced noise in a system. The three-dimensional domain using k–ε turbulence model and Ffowcs Williams and Hawkings (FW-H) acoustic model is considered to predict noise generated by the fan blade surface. The acoustic and flow performances of the fan are predicted simultaneously using a computational aero-acoustic technique (combining steady flow and noise propagation analysis). The different cases are simulated by varying the blade angle, blade depth, blade width and serrations at trailing edge of fan blade. An impact of each of these parameter on A-weighted sound pressure level (SPL) and mass flow rate at outlet is determined. The numeric value of obtained A-weighted SPL by CFD simulation is found to be in close agreement with the experimental result within 5.4%. Finally, above mentioned parameters are varied in simulation and optimized design is proposed based on A-weighted SPL and cubic feet per minute (CFM). All simulations are carried out in commercially available CFD solver; ANSYS FLUENT 13.

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Initial Acute Animal Experiment Using a New Miniature Axial Flow Pump in Series With the Natural Heart

Artificial Organs ◽

10.1111/aor.12558 ◽

2015 ◽

Vol 39 (8) ◽

pp. 701-704 ◽

Cited By ~ 8

Author(s):

Eiji Okamoto ◽

Tetsuya Yano ◽

Yasuyuki Shiraishi ◽

Hidekazu Miura ◽

Tomoyuki Yambe ◽

...

Keyword(s):

Animal Experiment ◽

Axial Flow ◽

In Series ◽

Axial Flow Pump ◽

Flow Pump

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Effect of Next Generation Computer Graphic Card Blower Fan Speed on Thermal Performance and Acoustic Noise With Psychoacoustic Metrics

Advances in Electronic Packaging, Parts A, B, and C ◽

10.1115/ipack2005-73180 ◽

2005 ◽

Cited By ~ 1

Author(s):

Helen Ule ◽

Colin Novak ◽

Robert Gaspar ◽

Arunima Panigrahy ◽

Gamal Refai-Ahmed

Keyword(s):

Thermal Performance ◽

Acoustic Analysis ◽

Computer Graphic ◽

Acoustic Noise ◽

Power Level ◽

Axial Flow ◽

Thermal Testing ◽

Operating Speed ◽

Fan Speed ◽

Psychoacoustic Metrics

Graphic Processor Units (GPUs) on the latest models of computer graphic cards generate significant amounts of heat. In fact, the required dissipation rate is so large that cooling fans mounted on heat-sinks must be used to maintain satisfactory GPU temperatures. The packaging of these fans is small and similar designs have been used for cooling of electronic packaging for decades. The appropriate application of these fans as well as their optimal design for minimal noise generation and maximum air movement has not kept pace with that of large industrial sized fans. Where space limitations allow and heat transfer requirements dictate, blower type fans are implemented because they are capable of delivering relatively high flow rates in high impedance environments when they are compared to more traditional axial flow fans. The operation of these blower fans, particularly at high speeds, results in the generation of noise which is experienced by the user. Both computer manufacturers and consumers alike have deemed this noise to be excessive and annoying. The fan model predictions and the operational reality of the higher fan speeds needed to deliver increased air flow both lead to the reality of higher noise levels. The purpose of this study was to experimentally investigate the realized thermal and acoustic performance of a blower style fan-sink mounted on an advanced graphics port (AGP) card. The goal of this investigation was to determine what thermal benefits of higher flow rate are realized by the blower fan at the expense of increased noise emissions. The experimental results of thermal measurement results spanning the operating speed of the fan are presented and accompanied by the noise data. These data include both traditional acoustic analysis techniques using sound pressure and power level measurements as well as psychoacoustic metrics. The result of the thermal testing suggests that the rate of improvement in thermal performance decreases as the blower fan speed increases. As expected, an increase in noise level was also observed. Of particular interest were the results of the psychoacoustic analysis which indicate a similar detrimental effect with increased fan speed for some metrics, while other metrics indicate no change across the operating speed range of the blower fan.

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Effects of a 6-Week Straw Phonation in Water Exercise Program on the Aging Voice

Journal of Speech Language and Hearing Research ◽

10.1044/2020_jslhr-19-00124 ◽

2020 ◽

Vol 63 (4) ◽

pp. 1018-1032

Author(s):

Chia-Hsin Wu ◽

Roger W. Chan

Keyword(s):

Acoustic Analysis ◽

Vocal Tract ◽

Exercise Program ◽

Analysis Of Covariance ◽

Elderly Subjects ◽

Control Group ◽

Perceptual Evaluation ◽

Positive Effects ◽

Aging Voice ◽

Before And After

Purpose Semi-occluded vocal tract (SOVT) exercises with tubes or straws have been widely used for a variety of voice disorders. Yet, the effects of longer periods of SOVT exercises (lasting for weeks) on the aging voice are not well understood. This study investigated the effects of a 6-week straw phonation in water (SPW) exercise program. Method Thirty-seven elderly subjects with self-perceived voice problems were assigned into two groups: (a) SPW exercises with six weekly sessions and home practice (experimental group) and (b) vocal hygiene education (control group). Before and after intervention (2 weeks after the completion of the exercise program), acoustic analysis, auditory–perceptual evaluation, and self-assessment of vocal impairment were conducted. Results Analysis of covariance revealed significant differences between the two groups in smoothed cepstral peak prominence measures, harmonics-to-noise ratio, the auditory–perceptual parameter of breathiness, and Voice Handicap Index-10 scores postintervention. No significant differences between the two groups were found for other measures. Conclusions Our results supported the positive effects of SOVT exercises for the aging voice, with a 6-week SPW exercise program being a clinical option. Future studies should involve long-term follow-up and additional outcome measures to better understand the efficacy of SOVT exercises, particularly SPW exercises, for the aging voice.

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The Shikani HME: A New Tracheostomy Heat and Moisture Exchanger

Journal of Speech Language and Hearing Research ◽

10.1044/2020_jslhr-19-00107 ◽

2020 ◽

Vol 63 (9) ◽

pp. 2921-2929

Author(s):

Alan H. Shikani ◽

Elamin M. Elamin ◽

Andrew C. Miller

Keyword(s):

Ex Vivo ◽

Moisture Loss ◽

Speaking Valve ◽

Time Zero ◽

In Series ◽

Turbulent Airflow ◽

The Difference ◽

Loss Efficiency ◽

Heat And Moisture ◽

Lung Simulation

Purpose Tracheostomy patients face many adversities including loss of phonation and essential airway functions including air filtering, warming, and humidification. Heat and moisture exchangers (HMEs) facilitate humidification and filtering of inspired air. The Shikani HME (S-HME) is a novel turbulent airflow HME that may be used in-line with the Shikani Speaking Valve (SSV), allowing for uniquely preserved phonation during humidification. The aims of this study were to (a) compare the airflow resistance ( R airflow ) and humidification efficiency of the S-HME and the Mallinckrodt Tracheolife II tracheostomy HME (M-HME) when dry (time zero) and wet (after 24 hr) and (b) determine if in-line application of the S-HME with a tracheostomy speaking valve significantly increases R airflow over a tracheostomy speaking valve alone (whether SSV or Passy Muir Valve [PMV]). Method A prospective observational ex vivo study was conducted using a pneumotachometer lung simulation unit to measure airflow ( Q ) amplitude and R airflow , as indicated by a pressure drop ( P Drop ) across the device (S-HME, M-HME, SSV + S-HME, and PMV). Additionally, P Drop was studied for the S-HME and M-HME when dry at time zero (T 0 ) and after 24 hr of moisture testing (T 24 ) at Q of 0.5, 1, and 1.5 L/s. Results R airflow was significantly less for the S-HME than M-HME (T 0 and T 24 ). R airflow of the SSV + S-HME in series did not significant increase R airflow over the SSV or PMV alone. Moisture loss efficiency trended toward greater efficiency for the S-HME; however, the difference was not statistically significant. Conclusions The turbulent flow S-HME provides heat and moisture exchange with similar or greater efficacy than the widely used laminar airflow M-HME, but with significantly lower resistance. The S-HME also allows the innovative advantage of in-line use with the SSV, hence allowing concurrent humidification and phonation during application, without having to manipulate either device.

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