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  • 1. Tahamtan, Mahdi The Aerodynamic, Glottographic, and Acoustic Effects of Clear Speech.

    Doctor of Philosophy (Ph.D.), Bowling Green State University, 2022, Communication Disorders

    This dissertation investigated aerodynamic, glottographic, and acoustic differences between habitual and clear speech. Nine normal-speaking individuals (five cis female, 4 cis male) were asked to read six short sentences in four reading conditions: habitual reading, habitual reading while holding a mask to the face to capture airflow and oral air pressure, clear reading, and clear reading while holding the mask to the face. Mask-off conditions in both habitual and clear reading manners were used for acoustic analyses, and mask-on conditions were used for aerodynamic and glottographic analyses. The instruction for eliciting habitual speech was “Read each sentence as if you are talking with a friend across the table.” The instruction for eliciting clear speech was “Read the sentences as clearly as possible by enunciating well, as if someone is having trouble understanding you.” Acoustic and time-related results indicated that from habitual to clear speech: (1) sentence duration increased, (2) speaking rate decreased, (3) duration of stressed vowels and unvoiced fricatives increased, (4) voice onset time increased for some unvoiced plosives, (5) stop gap duration increased, (6) fundamental frequency did not change except for two stressed vowels in female speakers for which fo increased, and (7) intensity of stressed vowels and stop consonants increased, but not for unvoiced fricatives (except for /ʃ/). Aerodynamic results indicated that from habitual to clear speech, there was greater (1) oral air pressure, (2) average airflow, (3) total air volume, and (4) peak flow during the release of the voiceless bilabial stop, suggesting the influence of greater subglottal pressure. In contrast, there was little to no change in glottal dynamics such as EGG width, EGG height, EGG contact and open quotients, and glottal airflow timing measures. In this study, it might be inferred that clear speech was a phenomenon that is more related to subglottal pressure and oral cavity kinem (open full item for complete abstract)

    Committee: Ronald Scherer Ph.D. (Committee Chair); Steven Boone M.F.A. (Other); Brent Archer Ph.D. (Committee Member); Jason Whitfield Ph.D. (Committee Member) Subjects: Acoustics; Speech Therapy
  • 2. Rae, Rebecca Measures of Voice Onset Time: A Methodological Study

    Master of Science (MS), Bowling Green State University, 2018, Communication Disorders

    The current investigation aimed to compare four different measurement approaches for the determination of voice onset time for the six English stop consonants, where VOT is defined as the "burst to onset of phonation". The signals of interest were the wideband airflow, microphone, electroglottograph, and the spectrographic display. A primary question was whether the use of the wideband airflow signal results in shorter VOT measurements. Two adult males and two adult females produced "CV-the-CV" utterances (e.g.,"pa the pa") containing the six English stop consonants across two conditions, habitual vs. clear speech. Visual measurements were from the burst to the initial detection of phonation (IDP). The wideband airflow gave the shortest VOT measures. For habitual speech and for the voiceless stop consonants, the airflow signal revealed glottal airflow oscillations on average of 1.7 ms sooner than the microphone signal, 8.1 ms sooner than the EGG signal, and 13.6 ms sooner than spectrographic formant detection. The VOT differences between the airflow and microphone signals were not significant. For voiced stop consonants, the airflow signal typically also gave similar values of VOT as the microphone signal, and on average 6 ms sooner than the formant excitation and 5 ms sooner than the electroglottograph signal. The study emphasizes the finding that the initial detection of phonation often appears earlier after the consonant burst for the wideband airflow and microphone signals in comparison to the electroglottograph and spectrographic signals.

    Committee: Ronald Scherer PhD (Advisor); Jason Whitfield PhD (Committee Member); Brent Archer PhD (Committee Member) Subjects: Physiology; Speech Therapy
  • 3. Barreto, Ivanett Investigating Uniformity of Smokehouse Ventilation Parameters Using Computational Fluid Dynamics (CFD)

    Doctor of Philosophy, The Ohio State University, 2024, Food, Agricultural and Biological Engineering

    The smoking process for a food product involves the deposition and absorption of smoke on the product surface, followed by a drying step to reduce the product moisture content to a defined level. The uniformity of air velocity and temperature within a smokehouse significantly influences final product quality, including color, texture, and flavor. Additionally, process efficiency and production capacity depend on uniform heat and mass transfer at the surface for all products in the smokehouse. While Computational Fluid Dynamics (CFD) has been used to study airflow patterns, air velocity and temperature distributions due to ventilation systems, research on applications to airflow distribution in a smokehouse have been limited. The overall objective of this research was to develop and validate CFD simulations of a smokehouse ventilation system to investigate the applications to airflow uniformity within a smokehouse. A CFD simulation of airflow distribution in a smokehouse without product was developed and used to investigate the influence of smokehouse ventilation configuration on uniformity of air velocity. The ventilation system configuration with outlet vents positioned near the inlet vents at both sides of the smokehouse ceiling exhibited the highest air velocity uniformity index of 0.64. An investigation of three different outlet vent dimensions indicated that outlet vent size did not influence the uniformity of air velocity distribution within the empty smokehouse. The influence of model products in the smokehouse was investigated using the CFD simulation. The average air velocity at 20 locations decreased from 3.9 ±1.4 m/s to 2.7 ±0.90 m/s when the ratio of model product to smokehouse volume was increase from 0 to 0.047. The influence of ventilation configuration was also evaluated by comparing outlet vents positioned near the inlet vents at both sides of the smokehouse ceiling to the outlet vent located in the ceiling at the middle of the smokehouse. The ave (open full item for complete abstract)

    Committee: Dennis Heldman (Advisor); Sudhir Sastry (Committee Member); Sandip Mazumder (Committee Member); Osvaldo Campanella (Committee Member) Subjects: Engineering; Fluid Dynamics; Food Science
  • 4. Maharjan, Surendra Design and Fabrication of Piezoresistive Flexible Sensors based on Graphene/ Polyvinylidene Fluoride (PVDF) Nanocomposite

    Master of Science, University of Toledo, 2022, Mechanical Engineering

    In recent years, flexible and stretchable sensors have been a subject of intensive research to replace the traditional sensors made up of metal and semiconductors. This thesis has been conducted with the objective of exploring the possible applications of Graphene/PVDF nanocomposite in various kinds of flexible sensors as a potential sensing material. Initially, graphene/PVDF nanocomposite was synthesized by the solution-phase mixing method. A thin film of 20-22 μm was coated on a glass substrate to investigate the characteristics of the composite by using XRD and SEM techniques. This nanocomposite was best suited for piezoresistive-based sensors where the sensor senses the external stimuli and outputs the response in terms of change in electrical properties such as resistance, voltage, or current. The synthesized graphene/PVDF nanocomposite was coated on different kinds of substrates to make three different kinds of flexible sensors. They are airflow sensor, knittle pressure sensor, and accelerometer. The airflow sensor was designed and fabricated by applying a thin film of nanocomposite on the polyethylene (PE) substrate and placed inside a PVC pipe at an angle to the central axis of the pipe. The response of the sensor was tested by passing air at various speeds and recorded in terms of resistance change. The linearity and repeatability of the curves were observed. Temperature dependence on electrical conductivity was studied by heating and cooling the sample between room temperature and below the melting point of PVDF. Further, the sensing characteristics were simulated using COMSOL Multiphysics software, and the modeled data were compared with the experimental result. Another application of our in-house fabrication with the use of the nanocomposite is a knittle pressure sensor. The primary purpose of developing knittle pressure is to monitor health by either attaching to the skin or using it inside the health monitoring device. The use of fabric substrate a (open full item for complete abstract)

    Committee: Ahalapitity Jayatissa (Advisor) Subjects: Mechanical Engineering
  • 5. Gunatilaka, Chamindu Neonatal Airway Analysis Using Magnetic Resonance Imaging and Computational Fluid Dynamics

    PhD, University of Cincinnati, 2021, Arts and Sciences: Physics

    Newborns admitted to the neonatal intensive care unit can suffer from various respiratory diseases due to prematurity or abnormality. Tracheomalacia (TM) is an airway condition characterized by airway collapse during breathing. Newborns diagnosed with TM may require respiratory support for breathing and there is no reliable method to quantify the breathing effort. The standard diagnosis for TM is bronchoscopy. However, bronchoscopy cannot precisely evaluate the severity of the disease and measure the effect of airway motion on airflow. This study aims to quantify airflow measurements such as work of breathing, airway resistance, and pressure in the central airway (trachea and main bronchi). Magnetic resonance imaging (MRI) was used to obtain the airway anatomy and motion during the breathing cycle. The acquired MR images were reconstructed based on respiration to obtain four MR images that show four main breathing phases (end expiration, peak inspiration, end inspiration, and peak expiration). Airway surfaces were segmented from MR images to create virtual airway models. Surface registration between the airway surfaces at each phase of breathing was used to obtain the physiologic motion during the breathing cycle. However, MRI cannot quantify airflow measurements alone. Computational fluid dynamics (CFD) is a well-known technique to model the airflow in airway models derived from MRI. Virtual airway models, airflow rates and airway motion were obtained for each subject and used as inputs for the CFD simulation. The main bronchi's airflow rates were obtained using the lung tidal volumes and the free induction decay waveform. Using these techniques, three studies were performed to investigate the effect of TM on neonatal respiration. The first study investigates the effect of airway motion on breathing by comparing airflow measurements in dynamic airways with static airways in four subjects with TM and without TM. Results indicated that CFD simulations should be perfo (open full item for complete abstract)

    Committee: David Mast Ph.D. (Committee Chair); Zackary Cleveland Ph.D. (Committee Member); L. C. R. Wijewardhana Ph.D. (Committee Member); Jason Woods Ph.D. (Committee Member) Subjects: Radiology
  • 6. Lau, Hiu Yan Crystal Objective Measure of Two Musical Interpretations of an Excerpt from Berlioz's "La Mort d'Ophelie"

    Master of Science (MS), Bowling Green State University, 2020, Interdisciplinary Studies

    Objective: Art song is a unique genre in the realm of European classical music, which embraces the combined beauty of vocal melody, instrumental accompaniment, and text. In a performance context, the same composition can be performed with a variety of emotional interpretations. The purpose of this study was to determine sound production differences relative to two emotional interpretations in performing an excerpt from a classical art song. Methods/Design: The first author, a soprano with a master's degree in vocal performance, recorded an excerpt from “La Mort d'Ophelie” composed by Hector Berlioz (1803-69). The excerpt was sung in two contrasting musical interpretations: an “empathetic legato” approach, and a “sarcastic” approach with emphatic attacks. Microphone, airflow (Glottal Enterprises MSIF-2), and electroglottography (EGG; Kay Model 6103) signals were digitized. These recordings were analyzed for acoustic, airflow, and glottographic measures. The vowels in the musical excerpt were analyzed in terms of intensity, long term average spectra (LTAS), fundamental frequency vibrato rate and extent, vowel onset, intensity comparison of harmonic frequencies, and glottal measures based on electroglottograph waveforms. Results & Conclusions: Data analyses revealed that stressed vowels, when performed with the emphatic approach compared to the legato approach, had faster vowel onset, increased glottal adduction (relative to the EGGW25 measure), increased intensity of harmonics in the 1500 to 3000 Hz range, inferred increase in subglottal pressure, increased airflow for the /f/ consonant, and greater aspiration airflow for the plosives /t/ and /p/. The vibrato extent for both fo and airflow were both greater for the emphatic approach. Findings also revealed larger amplitude values of the EGG waveform, but this finding was not statistically significant. Long-term average spectrum (LTAS) analyses of the entire production displayed minor increases across all fo (open full item for complete abstract)

    Committee: Ronald C. Scherer Ph.D. (Advisor); Jane Rodgers D.M.A. (Committee Member); Emily Pence Brown Ph.D. (Committee Member); Robert Satterlee D.M.A. (Other) Subjects: Music; Music Education; Speech Therapy
  • 7. Tong, Xinjie Modeling of Indoor Environment and Ammonia Emission, Distribution, and Dispersion Within and From Manure-Belt Layer Houses

    Doctor of Philosophy, The Ohio State University, 2019, Food, Agricultural and Biological Engineering

    The U.S. egg industry is the world's second-largest egg producer with an annual production of 5.6 billion kilograms of eggs and provides 81,515 jobs and $22.77 billion to the economy. Due to the very large-scale and concentrated operations, the egg industry is facing crucial challenges in reducing its significant environmental impacts and solving indoor air quality problems. Egg production is a significant contributor of air emissions to the atmosphere, especially ammonia (NH3) emission, which has caused serious concerns on health and the environment, such as soil and water acidification, visibility impairment, and respiratory diseases. Effective management and mitigation of NH3 emissions from layer operations are urgently needed but are limited because of the lack of effective tools for estimating NH3 emissions. It is also in the egg industry's and the public's interests to understand the health and environmental impacts of NH3 on the neighboring communities. The U.S.EPA regulatory air dispersion model AERMOD needs to be evaluated for its performance in estimating NH3 dispersion after being emission from layer houses. In addition, heat stress is a serious problem in layer houses with annual losses of $61-98 million nationwide due to impaired egg production. Global warming further worsens the heat stress problem due to increasing events of hot weather and heavier precipitation. Exposure to high-concentration NH3 is another risk to layers and workers. It damages layers' immune system and egg production and affects workers' health. The problems of heat stress and NH3 exposure are aggravated in layer houses due to non-uniform airflow resulted from current ventilation systems. The knowledge of the spatial and temporal distribution of heat stress and NH3 concentrations inside layer houses is essential for assessing the associated risks of layers and workers and developing mitigation strategies, but is not yet available. This dissertation aims to fill the gap by de (open full item for complete abstract)

    Committee: Lingying Zhao (Advisor); Albert Heber (Committee Member); Jiqin Ni (Committee Member); Heather Allen (Committee Member); Ann Christy (Committee Member); Gil Bohrer (Committee Member) Subjects: Agricultural Engineering; Environmental Engineering
  • 8. Nandamudi, Srihimaja Aerodynamics of Vocal Vibrato

    Doctor of Philosophy (Ph.D.), Bowling Green State University, 2017, Communication Disorders

    Airflow vibrato is the fluctuation in average airflow while singing with vibrato. Understanding airflow vibrato relates to a deeper understanding of its importance to physiological, pedagogical, and clinical aspects. Two studies were performed to examine airflow vibrato. The subjects for Study 1 were four professional Western classical singers, and for Study 2 four highly trained amateur singers. Aerodynamic and acoustic measures were compared among vibrato, bleating (a primarily adductory gesture), and external epigastric pumping (EEP, a primarily subglottal pressure manipulation). Utterances included speaking (phonation and whisper) and singing (constant /a/ vowel, different pitches and loudness levels). Study 1 demonstrated how airflow vibrato compares with fundamental frequency (F0) and intensity vibrato. The correlation between rates of airflow and F0 vibrato was moderately strong. Mean airflow vibrato extents were larger for the female singers than for the male singers, and increased with pitch increase for all four singers. For the males, average airflow extent was 30 and 75 cm3/s for their lower and higher pitch, respectively, and for the females, 47 cm3/s and 94 cm3/s for their lower and higher pitch, respectively. Study 2 was undertaken to better understand sources of airflow vibrato. Airflow modulations were produced during singing with vibrato and also while bleating and with external epigastric pumping. Bleating had the fastest alteration rate (9.5-12 Hz), whereas the other types had similar rates (vibrato: 4.8-6.0 Hz; EEP: 6.0–7.5 Hz). During phonation (combining all conditions), bleating had the largest airflow modulation extents (on average 144 cm3/s, compared to 30 cm3/s for vibrato and 46 cm3/s for EEP). Overall results suggest that airflow vibrato typically leads F0 vibrato, and often has a more complex waveshape than F0 vibrato. Hypotheses generated from the study include: (1) A primarily subglottal pressure driven vibrato may provide relat (open full item for complete abstract)

    Committee: Ronald Scherer Ph.D. (Advisor); Alexander Goberman Ph.D. (Committee Member); Jason Whitfield Ph.D. (Committee Member); Mingsheng Li Ph.D. (Other) Subjects: Health Sciences; Music; Speech Therapy
  • 9. Tukur, Ahmed Reducing Airflow Energy Use in Multiple Zone VAV Systems

    Doctor of Philosophy (Ph.D.), University of Dayton, 2016, Engineering

    Variable Air Volume (VAV) systems are the most popular HVAC systems in commercial buildings. VAV systems are designed to deliver airflows at design conditions which only occur for a few hours in a year. Minimizing energy use in VAV systems requires reducing the amount of airflow delivered through the system at part load conditions. Air Handling Unit (AHU) fans are the major drivers of airflow in VAV systems and installing a Variable Frequency Drive (VFD) is the most common method of regulating airflow in VAV systems. A VFD drive does not necessarily save energy without use of an appropriate control strategy. Static pressure reset (SPR) is considered to be the most energy efficient control strategy for AHU fans with VFDs installed. The implementation of SPR however has many challenges; for example, rogue zones—zones which have faulty sensors or failed controls and actuators, system dynamics like hunting and system diversity. By investigating the parameters associated with the implementation of SPR in VAV systems, a new, improved, more stable SPR algorithm was developed and validated. This approach was further improved using Fault Detection and Diagnostics (FDD) to eliminate rogue zones. Additionally, a CO2-Demand Control Ventilation (DCV) based minimum airflow control was used to further reduce ventilation airflow and save more energy from SPR. Energy savings ranging from 25% to 51% were recorded in actual buildings with the new SPR algorithm. Finally, a methodology that utilizes historical VAV data was developed to estimate the potential savings that could be realized using SPR. The approach employed first determines an effective system loss coefficient as a function of mean damper position using the historical duct static pressure, VAV damper positions and airflows. Additionally, the historical data is used to identify the maximum mean duct damper position realizable as a result of insuring a sufficient number of VAVs are fully open at any time. Savings ar (open full item for complete abstract)

    Committee: Kevin Hallinan (Committee Chair); Kelly Kissock (Committee Co-Chair); Andrew Chiasson (Committee Member); Zhenhua Jiang (Committee Member) Subjects: Energy; Engineering; Mechanical Engineering
  • 10. Shakya, Rikesh Mass Airflow Sensor and Flame Temperature Sensor for Efficiency Control of Combustion Systems

    Master of Science in Engineering, University of Akron, 2015, Electrical Engineering

    A premixed mixture for a combustion process is said to be stoichiometric when the amount of air provided is just enough to burn the fuel completely. A parameter called the equivalence ratio gives a measure of the closeness of the combustion system to stoichiometric combustion. In practice, excess air is provided in a combustion system to avoid production of harmful flue gases. The amount of fuel and air intake in a combustion process along with their degree of mixing affects its efficiency. This thesis describes the design of a mass airflow sensor and a flame temperature sensor that can be used to estimate mass airflow rate and equivalence ratio respectively, thereby enabling control of the efficiency of combustion systems. The mass airflow sensor designed for this thesis is an inline airflow sensor that can be used to measure combustion intake air in the temperature range between -40°F to 140°F and mass airflow rate between 0 kg/hr to 120 kg/hr. The mass airflow sensor is based on the principle of constant temperature difference thermal mass airflow meter. Thermistors are used as resistive elements for the mass airflow meter discussed in this thesis. The sensor was calibrated considering the wide range of operation of temperature; and mechanical and electrical tolerance of thermistors used in the sensor. The performance of the sensor with disturbances in combustion air intake and the effect of dust being deposited on the sensor were also studied. The flame temperature sensor is based on using Silicon Nitride hot surface igniter as a dual purpose sensor for both ignition and temperature measurement. The flame temperature measurement is based on resistance variation property of the Silicon Nitride hot surface igniter with temperature. The flame temperature of the combustion system along with the knowledge of mass airflow rate of air intake was employed to calculate the equivalence ratio of the system between 0.6 and 1. Different types of sensors from Kyocera and Coor (open full item for complete abstract)

    Committee: Nathan Ida (Advisor); Joan Carletta (Committee Member); Kye-Shin Lee (Committee Member) Subjects: Electrical Engineering
  • 11. Blanchard, Eric Legato Trombone: A Survey of Pedagogical Resources

    DMA, University of Cincinnati, 2010, College-Conservatory of Music : Trombone

    The purpose of this document was to explore the pedagogical techniques of legato trombone. Professional trombone books, method books, articles and web-pages were surveyed in order to understand legato pedagogy and to see if there were changes over the past century or differences in pedagogy throughout world regions. The most common legato pedagogy was highlighted and used in comparison to pedagogy taught in three distinct areas of literature: trombone specific method books, brass method books for pre-service and in-service music educators, and beginning band methods. This comparison was used to reveal gaps between the pedagogical techniques shown in beginning band methods and those that are generally accepted by trombone pedagogues. Through this survey, those methods books which best apply the professional pedagogy are endorsed. Tables containing comprehensive lists of trombone specific method books, brass method books for pre-service and in-service music educators, and beginning band methods are found in the appendices. These tables supply data concerning the legato pedagogy in each method book, which allows trombonists and music educators to quickly compare the pedagogy in method books. It is hoped that through this project the understanding of legato performance on trombone will increase. This will enable pedagogues of beginning, intermediate, and advanced trombone students to use the best possible and most personally adequate techniques in teaching legato trombone.

    Committee: Timothy Anderson MM (Committee Chair); Ann Porter PhD (Committee Member); Timothy Northcut MM (Committee Member) Subjects: Music
  • 12. Rojatkar, Prachi Numerical Simulation of 3-D Turbulent Room Airflow Pattern and Temperature Field in UC Solar Decathlon House

    MS, University of Cincinnati, 2007, Engineering : Mechanical Engineering

    In this study Computational Fluid Dynamics (CFD) has been used to simulate the airflow and temperature distribution patterns inside a Solar House (designed by University of Cincinnati team to compete in Solar Decathlon 2007) over a range of environmental conditions. Analysis of airflow and temperature field is presented for mechanically driven heating and cooling system (forced convection) and radiant floor heating system (natural convection). Main objective of the study is to analyze the design parameters for heating and cooling of the house with respect to indoor air distribution pattern and temperature field. Compliance with Solar Decathlon norms for indoor air temperature is also studied and corrective suggestions are made. Finally, thermal comfort for three major areas of the house (living/kitchen, bedroom and bathroom) is evaluated for each case. It can be concluded from the CFD study that the system design is satisfactory for the given house structure and will fulfill the requirements of thermal comfort.

    Committee: Michael Kazmierczak (Committee Co-Chair); Rupak Banerjee (Committee Co-Chair); Anton Harfmann (Other); David Car (Other) Subjects: Engineering, Mechanical
  • 13. May, Shelley Repeatability of Aerodynamic Measures in Children, Ages 4.0-5.11 Years

    Master of Arts, Miami University, 2010, Speech Pathology and Audiology

    The purpose of this study was to determine the short-term repeatability of average airflow in children, ages 4.0 – 5.11 years. Thirty participants with healthy voices and normal hearing sustained the vowel /a/ for 5 seconds at their comfortable frequency and intensity for 3 consecutive productions during 2 separate trials, using the Phonatory Aerodynamic System. The trials were separated by performance of additional acoustic tasks. Results indicated that average airflow measurements were repeatable in young children with no significant difference in average airflow values.

    Committee: Barbara Weinrich PhD (Advisor); Susan Baker Brehm PhD (Committee Member); Wendy LeBorgne PhD (Committee Member) Subjects: Speech Therapy
  • 14. Grodek, Kristen The Effect of Sound Pressure Level Variation on Aerodynamic Measures

    Master of Arts, Miami University, 2009, Speech Pathology and Audiology

    The purpose of this study was to examine the effects of varying intensity levels on average airflow and estimated subglottal pressure measurements and to examine the repeatability of these measurements over short-term (10 minute) and long-term (one week) time periods. Thirty females between the ages of 18 and 25 years with healthy voices were recruited from the Oxford, Ohio area to participate in this study. Aerodynamic measures of the voice were obtained using the Phonatory Aerodynamic System. The same protocol was followed for all three sessions, with average airflow and estimated subglottal pressure being examined during loud, comfortable, and soft phonatory levels. Results of the study indicated that mean average airflow and mean estimated subglottal pressure measures are consistent over short-term and long-term periods. The study also found that subject perceived changes of intensity variation had a significant effect on estimated subglottal pressure measures, but not on average airflow measures. The results of this study support the repeatability of aerodynamic measures, the reliability of their use, and information that contributes to clinical assessments of voice disorders.

    Committee: Susan Baker Brehm PhD (Advisor); Barbara Weinrich PhD (Committee Member); Wendy LeBorgne PhD (Committee Member) Subjects: Speech Therapy
  • 15. Garrison, Courtney Repeatability of Aerodynamic Measurements of Voice

    Master of Arts, Miami University, 2009, Speech Pathology and Audiology

    The purpose of this study was to compare baseline aerodynamic measurements of voice to measurements repeated after a 10-minute break and a one week break. Average airflow and estimated subglottal pressure measurements were gathered from females between 18 and 24 years of age with healthy voices. Each participant's frequency and intensity was held constant during each testing session. Results indicated that aerodynamic measurements of average airflow and estimated subglottal pressure were repeatable, as there were no significant differences between mean measurements taken during each testing session. The results of this study provided support for the clinical use of average airflow and estimated subglottal pressure for voice assessments and treatment data.

    Committee: Barbara Weinrich PhD (Committee Chair); Susan Baker Brehm PhD (Committee Member); Wendy LeBorgne PhD (Committee Member) Subjects: Speech Therapy
  • 16. Shupe, Andrew Convective Flow Patterns of a Three Generation Bifurcation Model

    Master of Science in Mechanical Engineering, University of Toledo, 2012, Mechanical Engineering

    To experimentally study the convective flow patterns of the human lung, a large scale symmetric model was built to model branching airways that air passes through during respiration. The model used in this experiment goes through three symmetrical 70¿¿ bifurcations before terminating at the model exits. The model not only demonstrated in-plane flow but was rotated to represent out-of-plane flow after each bifurcation. In the latter case the model was rotated 90¿¿ at each of the bifurcations, which allowed a more realistic study of the three-dimensional branching flow inside the lung. For each case the flow was studied at inlet Reynolds numbers of 750 and 1500. The airflow was studied using a parabolic inlet condition and was only representative of inspiratory flow. In order to visualize the flow in the model a laser was expanded though a cylindrical lens to produce a laser sheet that was directed through the exit plane flow field of each bifurcation. When shining the laser sheet through the flow-field, the size, shape, and location of vortices could be visually identified. A Laser Doppler Anemometer (LDA) was used to measure the velocity patterns in the model. The LDA was used to measure both the primary (normal) velocity component and the secondary (tangential) velocity components of the flow at the entrance and at the exits of each bifurcation. This data was then used to reveal the flow field for each model configuration. When considering the in-plane (non-rotated) model, the flow development after one bifurcation was fairly predictable and developed into two distinct vortices at each exit. The two vortices were symmetrical and were located toward the inner wall of curvature. The formation and position of the vortices were in agreement with many previous curved flow studies and could be predicted from curved pipe simulations. Numerically this was also calculated, for example by Soriropoulos (26), for a non-bifurcating curved tube. At the in-plane second bi (open full item for complete abstract)

    Committee: Dr. Terry Ng PhD (Committee Chair); Dr. Daniel Olson PhD (Committee Member); Dr. Sorin Cioc PhD (Committee Member) Subjects: Biomedical Engineering; Fluid Dynamics; Mechanical Engineering